Severe Storms

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sun Jun 30 2024 Valid 301630Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHERN NEW ENGLAND AND THE EASTERN MID-ATLANTIC... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered to numerous damaging wind gusts are likely across parts of the Northeast and Mid-Atlantic States this afternoon and evening. Large hail and severe/damaging winds should also occur from southern Montana into western North Dakota. ...Northeast/Mid-Atlantic into the Carolinas... A mid-level trough over the Great Lakes and eastern Canada will continue moving eastward through the period. An associated cold front will likewise advance east-southeastward across New England and much of the Mid-Atlantic through this evening. Based on area 12Z soundings and recent surface observations, a very moist airmass is in place ahead of the front, with surface dewpoints generally in the low to mid 70s. Filtered daytime heating with broken cloud cover will support weak to moderate instability through late this afternoon, with most guidance continuing to suggest a narrow corridor of 1000-2000 J/kg MLCAPE will be in place along/near the I-95 corridor from southern New England to the eastern Mid-Atlantic. Mid-level flow will increase through the day in tandem with the upper trough, which will foster strong deep-layer shear and organized convection. Expectations are for thunderstorms to continue increasing in coverage and intensity this afternoon, both along/ahead of the cold front and a pre-frontal surface trough. Multiple rounds of intense convection appear possible. Given a rather favorable thermodynamic and kinematic parameter space, swaths of severe/damaging winds generally 60-70 mph will likely occur as a mix of bowing line segments/clusters and a few supercells sweep eastward through the afternoon/evening. No changes have been made to the Enhanced Risk across parts of southern New England into the Mid-Atlantic, where the greatest concentration of damaging winds is still anticipated. Isolated hail and perhaps a tornado may also occur with any sustained supercell, although poor mid-level lapse rates and modest/veered low-level flow should hinder both of these threats, respectively. Deep-layer shear will be weaker with southward extent across the Mid-Atlantic into the Carolinas. Convective mode should also tend to be mainly multicellular across these regions. Even so, steepened low-level lapse rates and ample instability should support a threat for scattered damaging winds as thunderstorms develop and spread eastward to the Atlantic Coast this afternoon/evening. ...Northern/Central High Plains... A mid-level shortwave trough evident over the Northwest this morning will progress eastward across the northern Rockies and adjacent High Plains through tonight. A surface lee cyclone is forecast to deepen and consolidate over northern WY/southeast MT by this evening, as large-scale ascent preceding the upper trough overspreads the northern High Plains. Even though low-level moisture is expected to remain rather limited across this area, steep lapse rates and daytime heating will contribute to at least weak instability developing by late afternoon. Moderate to strong deep-layer shear will support updraft organization. Cellular convection that initially develops over the higher terrain of southwest MT and vicinity should quickly grow upscale into a small bowing cluster as it moves east-northeastward across central/eastern MT this evening. Large hail may occur initially, but a transition to mainly a severe/damaging wind threat appears likely as this mode transition occurs. Isolated significant severe wind gusts (75-80 mph) appear possible given the very steep/favorable low/mid-level lapse rates expected. This wind threat may continue into parts of western ND and vicinity tonight before convection eventually weakens. Farther south, isolated to scattered thunderstorms should develop along/east of the higher terrain from WY into CO. Various NAM/RAP forecast soundings across this area show favorable shear for organized convection, including the potential for a mix of multicells and perhaps a couple of supercells. The southern fringe of the stronger mid-level flow and the northwest edge of the monsoonal moisture may overlap enough in western CO to support an isolated threat for severe wind gusts. ...Arizona... Low/mid-level moisture should gradually increase through the period on the western periphery of a mid/upper-level high centered over the southern Plains. Diurnal heating in the wake of overnight convection should occur across the higher terrain of eastern/southeast AZ through this afternoon, which will aid in the development of weak to moderate instability. Expectations are for thunderstorms to initially form over the higher terrain, and then slowly westward late this afternoon and evening in response to around 15-20 kt of east-southeasterly mid-level flow. A very well mixed boundary layer, with steep lapse rates through much of the troposphere, should support a threat for isolated strong to severe wind gusts with this high-based convection. ..Gleason/Thornton.. 06/30/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sun Jun 30 2024 Valid 301630Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHERN NEW ENGLAND AND THE EASTERN MID-ATLANTIC... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered to numerous damaging wind gusts are likely across parts of the Northeast and Mid-Atlantic States this afternoon and evening. Large hail and severe/damaging winds should also occur from southern Montana into western North Dakota. ...Northeast/Mid-Atlantic into the Carolinas... A mid-level trough over the Great Lakes and eastern Canada will continue moving eastward through the period. An associated cold front will likewise advance east-southeastward across New England and much of the Mid-Atlantic through this evening. Based on area 12Z soundings and recent surface observations, a very moist airmass is in place ahead of the front, with surface dewpoints generally in the low to mid 70s. Filtered daytime heating with broken cloud cover will support weak to moderate instability through late this afternoon, with most guidance continuing to suggest a narrow corridor of 1000-2000 J/kg MLCAPE will be in place along/near the I-95 corridor from southern New England to the eastern Mid-Atlantic. Mid-level flow will increase through the day in tandem with the upper trough, which will foster strong deep-layer shear and organized convection. Expectations are for thunderstorms to continue increasing in coverage and intensity this afternoon, both along/ahead of the cold front and a pre-frontal surface trough. Multiple rounds of intense convection appear possible. Given a rather favorable thermodynamic and kinematic parameter space, swaths of severe/damaging winds generally 60-70 mph will likely occur as a mix of bowing line segments/clusters and a few supercells sweep eastward through the afternoon/evening. No changes have been made to the Enhanced Risk across parts of southern New England into the Mid-Atlantic, where the greatest concentration of damaging winds is still anticipated. Isolated hail and perhaps a tornado may also occur with any sustained supercell, although poor mid-level lapse rates and modest/veered low-level flow should hinder both of these threats, respectively. Deep-layer shear will be weaker with southward extent across the Mid-Atlantic into the Carolinas. Convective mode should also tend to be mainly multicellular across these regions. Even so, steepened low-level lapse rates and ample instability should support a threat for scattered damaging winds as thunderstorms develop and spread eastward to the Atlantic Coast this afternoon/evening. ...Northern/Central High Plains... A mid-level shortwave trough evident over the Northwest this morning will progress eastward across the northern Rockies and adjacent High Plains through tonight. A surface lee cyclone is forecast to deepen and consolidate over northern WY/southeast MT by this evening, as large-scale ascent preceding the upper trough overspreads the northern High Plains. Even though low-level moisture is expected to remain rather limited across this area, steep lapse rates and daytime heating will contribute to at least weak instability developing by late afternoon. Moderate to strong deep-layer shear will support updraft organization. Cellular convection that initially develops over the higher terrain of southwest MT and vicinity should quickly grow upscale into a small bowing cluster as it moves east-northeastward across central/eastern MT this evening. Large hail may occur initially, but a transition to mainly a severe/damaging wind threat appears likely as this mode transition occurs. Isolated significant severe wind gusts (75-80 mph) appear possible given the very steep/favorable low/mid-level lapse rates expected. This wind threat may continue into parts of western ND and vicinity tonight before convection eventually weakens. Farther south, isolated to scattered thunderstorms should develop along/east of the higher terrain from WY into CO. Various NAM/RAP forecast soundings across this area show favorable shear for organized convection, including the potential for a mix of multicells and perhaps a couple of supercells. The southern fringe of the stronger mid-level flow and the northwest edge of the monsoonal moisture may overlap enough in western CO to support an isolated threat for severe wind gusts. ...Arizona... Low/mid-level moisture should gradually increase through the period on the western periphery of a mid/upper-level high centered over the southern Plains. Diurnal heating in the wake of overnight convection should occur across the higher terrain of eastern/southeast AZ through this afternoon, which will aid in the development of weak to moderate instability. Expectations are for thunderstorms to initially form over the higher terrain, and then slowly westward late this afternoon and evening in response to around 15-20 kt of east-southeasterly mid-level flow. A very well mixed boundary layer, with steep lapse rates through much of the troposphere, should support a threat for isolated strong to severe wind gusts with this high-based convection. ..Gleason/Thornton.. 06/30/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sun Jun 30 2024 Valid 301630Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHERN NEW ENGLAND AND THE EASTERN MID-ATLANTIC... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered to numerous damaging wind gusts are likely across parts of the Northeast and Mid-Atlantic States this afternoon and evening. Large hail and severe/damaging winds should also occur from southern Montana into western North Dakota. ...Northeast/Mid-Atlantic into the Carolinas... A mid-level trough over the Great Lakes and eastern Canada will continue moving eastward through the period. An associated cold front will likewise advance east-southeastward across New England and much of the Mid-Atlantic through this evening. Based on area 12Z soundings and recent surface observations, a very moist airmass is in place ahead of the front, with surface dewpoints generally in the low to mid 70s. Filtered daytime heating with broken cloud cover will support weak to moderate instability through late this afternoon, with most guidance continuing to suggest a narrow corridor of 1000-2000 J/kg MLCAPE will be in place along/near the I-95 corridor from southern New England to the eastern Mid-Atlantic. Mid-level flow will increase through the day in tandem with the upper trough, which will foster strong deep-layer shear and organized convection. Expectations are for thunderstorms to continue increasing in coverage and intensity this afternoon, both along/ahead of the cold front and a pre-frontal surface trough. Multiple rounds of intense convection appear possible. Given a rather favorable thermodynamic and kinematic parameter space, swaths of severe/damaging winds generally 60-70 mph will likely occur as a mix of bowing line segments/clusters and a few supercells sweep eastward through the afternoon/evening. No changes have been made to the Enhanced Risk across parts of southern New England into the Mid-Atlantic, where the greatest concentration of damaging winds is still anticipated. Isolated hail and perhaps a tornado may also occur with any sustained supercell, although poor mid-level lapse rates and modest/veered low-level flow should hinder both of these threats, respectively. Deep-layer shear will be weaker with southward extent across the Mid-Atlantic into the Carolinas. Convective mode should also tend to be mainly multicellular across these regions. Even so, steepened low-level lapse rates and ample instability should support a threat for scattered damaging winds as thunderstorms develop and spread eastward to the Atlantic Coast this afternoon/evening. ...Northern/Central High Plains... A mid-level shortwave trough evident over the Northwest this morning will progress eastward across the northern Rockies and adjacent High Plains through tonight. A surface lee cyclone is forecast to deepen and consolidate over northern WY/southeast MT by this evening, as large-scale ascent preceding the upper trough overspreads the northern High Plains. Even though low-level moisture is expected to remain rather limited across this area, steep lapse rates and daytime heating will contribute to at least weak instability developing by late afternoon. Moderate to strong deep-layer shear will support updraft organization. Cellular convection that initially develops over the higher terrain of southwest MT and vicinity should quickly grow upscale into a small bowing cluster as it moves east-northeastward across central/eastern MT this evening. Large hail may occur initially, but a transition to mainly a severe/damaging wind threat appears likely as this mode transition occurs. Isolated significant severe wind gusts (75-80 mph) appear possible given the very steep/favorable low/mid-level lapse rates expected. This wind threat may continue into parts of western ND and vicinity tonight before convection eventually weakens. Farther south, isolated to scattered thunderstorms should develop along/east of the higher terrain from WY into CO. Various NAM/RAP forecast soundings across this area show favorable shear for organized convection, including the potential for a mix of multicells and perhaps a couple of supercells. The southern fringe of the stronger mid-level flow and the northwest edge of the monsoonal moisture may overlap enough in western CO to support an isolated threat for severe wind gusts. ...Arizona... Low/mid-level moisture should gradually increase through the period on the western periphery of a mid/upper-level high centered over the southern Plains. Diurnal heating in the wake of overnight convection should occur across the higher terrain of eastern/southeast AZ through this afternoon, which will aid in the development of weak to moderate instability. Expectations are for thunderstorms to initially form over the higher terrain, and then slowly westward late this afternoon and evening in response to around 15-20 kt of east-southeasterly mid-level flow. A very well mixed boundary layer, with steep lapse rates through much of the troposphere, should support a threat for isolated strong to severe wind gusts with this high-based convection. ..Gleason/Thornton.. 06/30/2024 Read more

MD 1488 CONCERNING SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY FOR MAINE AND NEW HAMPSHIRE
Mesoscale Discussion 1488 NWS Storm Prediction Center Norman OK 0934 AM CDT Sun Jun 30 2024 Areas affected...Maine and New Hampshire Concerning...Severe potential...Severe Thunderstorm Watch likely Valid 301434Z - 301630Z Probability of Watch Issuance...80 percent SUMMARY...Thunderstorm coverage/intensity will gradually increase into early afternoon. Damaging gusts and isolated hail will be possible. A severe thunderstorm watch will likely be needed in the next couple of hours. DISCUSSION...Scattered thunderstorms have already developed this morning across portions of southern Quebec ahead of an eastward-advancing cold front. Downstream from this activity, modest/gradual destabilization is occurring across NH/ME where heating is occurring amid scattered/broken clouds. Stronger heating and richer boundary-layer moisture will likely remain focused across parts of NH into western/coastal ME. Nevertheless, strong vertical shear will remain in place over the area and instability will be sufficient for bands/clusters of strong/severe storms into the afternoon hours. Forecast soundings show a deeply mixed boundary layer with steep low level lapse rates amid 45+ kt effective shear by early afternoon, supporting damaging wind potential. Straight, elongated hodographs also suggest hail may be possible with any more discrete storm mode. A severe thunderstorm watch will likely be needed for portions of the area within the next couple of hours. ..Leitman/Gleason.. 06/30/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CAR...GYX...BTV... LAT...LON 46936760 45146690 44086809 43087095 43317167 43677184 45357128 47006981 47196947 47226831 46936760 Read more

MD 1487 CONCERNING SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY FOR PORTIONS OF THE MID-ATLANTIC AND SOUTHERN NEW ENGLAND
Mesoscale Discussion 1487 NWS Storm Prediction Center Norman OK 0855 AM CDT Sun Jun 30 2024 Areas affected...portions of the Mid-Atlantic and southern New England Concerning...Severe potential...Severe Thunderstorm Watch likely Valid 301355Z - 301600Z Probability of Watch Issuance...80 percent SUMMARY...Thunderstorm coverage will gradually increase in coverage/intensity through midday. Swaths of damaging wind gusts are expected through afternoon. One or more severe thunderstorm watches will likely be needed in the next couple of hours for portions of the Mid-Atlantic into New England. DISCUSSION...A very moist airmass is already in place across the region this morning, with surface dewpoints in the low to mid 70s F noted in observations. Temperatures are already in the upper 70s to low 80s, and even modest heating through broken clouds will aid in further destabilization toward midday. 12z RAOBs from ALB and OKX also indicate a strongly sheared environment, with effective shear magnitudes greater than 40 kt present. Early convection is already noted near Binghamton NY along an outflow boundary. Additional convection is developing further west across central PA ahead of an east/southeast-advancing cold front. As convection gradually increases over the next few hours, bowing segments/clusters are expected given mostly unidirectional deep-layer flow. Large instability, high PW values, and steepening low-level lapse rates amid favorable shear will support swaths of damaging winds across the region through the afternoon into early evening. One or more watches will likely be needed for the region within the next couple of hours. ..Leitman/Gleason.. 06/30/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX...BOX...OKX...ALY...PHI...BGM...CTP...LWX... LAT...LON 42087612 42887429 43017286 42997153 42917079 42557045 41937050 41627060 40257239 39747343 39197460 39307544 39417600 39867669 40327696 40717692 41487664 42087612 Read more

WW 0489 Status Updates
STATUS FOR WATCH 0489 HAS NOT BEEN ISSUED YET Read more

No watches are valid as of Sun Jun 30 14:37:01 UTC 2024.

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 AM CDT Sun Jun 30 2024 Valid 301300Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE I-95/NEAR-COASTAL CORRIDOR FROM THE DELAWARE VALLEY TO SOUTHEASTERN NEW ENGLAND...INCLUDING THE NEW YORK CITY METRO... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK FROM NORTHERN NORTH CAROLINA TO NEW ENGLAND...AND ALSO OVER PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered damaging winds will be possible across parts of the Northeast and Mid-Atlantic States this afternoon/evening. Hail and damaging winds may also occur from eastern Montana into western North Dakota. ...Synopsis... In mid/upper levels, the synoptic pattern over the CONUS will remain dominated by progressive troughs in the Northwest to northern Rockies, and in the Great Lakes to Northeast. An anticyclone aloft, attached to a more extensive, zonal, subtropical ridge, will remain anchored over the southern Plains. What will become the main shortwave perturbation associated with the Northeast trough is apparent over portions of the Upper Great Lakes and MI, and will amplify while moving over southern ON around 00Z. A sharp shortwave trough should result overnight, extending from northern VT across eastern NY to northern WV by 12Z tomorrow. Meanwhile, a series of minor/low-amplitude shortwaves and vorticity lobes will eject northeastward ahead of the Northwest trough, across the central/northern Rockies. A weak, convectively induced perturbation now near the southern AZ border should move slowly northwestward around the subtropical ridging. The northern part of another trough in the mid/upper easterlies is evident in moisture- channel imagery from the MX coastline northwest of Mazatlan, northward to at least southern Chihuahua, moving northwestward. The 11Z surface analysis showed a low over south-central QC, with cold front southwestward over Lake Ontario, southwestern OH, northern/western KY, north-central OK, to east-central NM. By 00Z the cold front should reach parts of ME, southeastern NY, northern VA, central AL, and southern OK, becoming a quasistationary to warm front over the TX Panhandle to northeastern NM. By the end of the period, this boundary should move offshore north of the Outer Banks of NC, and extend over central GA, southern AL/MS, the Red River Valley of TX/OK, and southeastern CO. Separate cyclogenesis should occur today over south-central/southeastern MT, with cold front southwestward across parts of the Great Basin. ...Northern/middle Atlantic Seaboard... Scattered thunderstorms -- mainly in lines but with some discrete activity -- are expected to move mostly eastward across this corridor from late morning through early evening in episodes, with damaging winds likely, a few embedded severe gusts possible, and isolated potential for large hail or a tornado. Low/middle-level destabilization will occur in the preconvective/ prefrontal environment throughout the day, essentially removing already weak MLCINH. This will occur via diurnal heating of the surface and large-scale lift ahead of the approaching Great Lakes trough aloft. Steepening boundary-layer lapse rates amid rich low-level moisture, with dewpoints commonly in the upper 60s to low 70s F, will offset modest mid/upper-level lapse rates enough to foster peak/preconvective MLCAPE in the 1500-2500 J/kg range. Greatest buoyancy is possible over the coastal plain between the Delmarva peninsula and eastern MA. Wind profiles will be largely unidirectional from the southwest or west-southwest, limiting low-level hodograph size and overall vertical shear. However, strengthening flow aloft with northward extent will support increasing potential for a few supercells northward from the northern Mid-Atlantic into New England, and especially across ME. A counterbalancing effect, however, will be diminishing buoyancy with northward extent over New England. Farther south over much of VA and NC, weak shear will support predominantly multicellular storm modes, with damaging/isolated severe gusts possible in water-loaded downdrafts. ...Northern Plains to central Rockies/High Plains... Scattered to isolated thunderstorms should develop over the central Rockies and higher terrain near the Four Corners and move northeastward to eastward this afternoon -- some of it out onto the central High Plains. Activity should produce locally strong-severe gusts and isolated large hail from downdrafts penetrating deep, well-mixed subcloud layers, though vertical shear this far south of the main flow belt should remain too weak to support well-organized severe potential. Farther north, however, a better-organized severe threat may occur this evening with later-developing convection in the northern Rockies and adjacent High Plains. Increasing large-scale ascent ahead of the Northwest trough will support this activity, along with backed low-level flow and strengthening convergence positioned poleward of the deepening surface low. Early-stage convection may include a few supercells with large hail and damaging gusts, with some convection potentially expanding upscale into one or more clusters as it encounters greater low-level moisture content across central/eastern MT. Large hail will remain possible -- especially with embedded supercell(s), and the severe-gust threat should increase with potential for mesobeta-scale cold-pool development, especially considering the moderately high LCL. A narrow corridor of mid 40s to mid 50s F surface dewpoints, and steep low/middle- level lapse rates, should support MLCAPE in the 1000-1500 J/kg range (locally/briefly higher). Veering winds with height will contribute to effective-shear magnitudes in the 45-55-kt range in support of storm organization. ...Central/southeastern AZ... Cloud debris and mostly light lingering precip are evident over southern AZ, related to the first perturbation, with warming IR cloud tops and overall thinning of clouds noted in recent satellite trends. This should continue and shift northwestward with the initial perturbation through midday into early afternoon, allowing for diurnal heating/destabilization of the boundary layer over southeastern AZ by mid/late afternoon. This, along with favorable low-level moisture, orographic forcing, and weak large-scale ascent preceding the next perturbation aloft, will support widely scattered to scattered afternoon thunderstorms, some of which may produce severe gusts. Valley-floor dewpoints in the 50s F largely should be maintained through the heating/mixing cycle, beneath very steep low-level lapse rates and a well-mixed subcloud layer. A deep southeasterly wind profile in low and middle levels will support northwestward motion of activity, which may aggregate their outflows to encourage both reinforcing development and localized channels of strong-severe wind. The somewhat delayed nature of the destabilization process, and uncertainties about storm coverage/aggregation, preclude greater unconditional probabilities at this time. ..Edwards/Kerr.. 06/30/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 AM CDT Sun Jun 30 2024 Valid 301300Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE I-95/NEAR-COASTAL CORRIDOR FROM THE DELAWARE VALLEY TO SOUTHEASTERN NEW ENGLAND...INCLUDING THE NEW YORK CITY METRO... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK FROM NORTHERN NORTH CAROLINA TO NEW ENGLAND...AND ALSO OVER PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered damaging winds will be possible across parts of the Northeast and Mid-Atlantic States this afternoon/evening. Hail and damaging winds may also occur from eastern Montana into western North Dakota. ...Synopsis... In mid/upper levels, the synoptic pattern over the CONUS will remain dominated by progressive troughs in the Northwest to northern Rockies, and in the Great Lakes to Northeast. An anticyclone aloft, attached to a more extensive, zonal, subtropical ridge, will remain anchored over the southern Plains. What will become the main shortwave perturbation associated with the Northeast trough is apparent over portions of the Upper Great Lakes and MI, and will amplify while moving over southern ON around 00Z. A sharp shortwave trough should result overnight, extending from northern VT across eastern NY to northern WV by 12Z tomorrow. Meanwhile, a series of minor/low-amplitude shortwaves and vorticity lobes will eject northeastward ahead of the Northwest trough, across the central/northern Rockies. A weak, convectively induced perturbation now near the southern AZ border should move slowly northwestward around the subtropical ridging. The northern part of another trough in the mid/upper easterlies is evident in moisture- channel imagery from the MX coastline northwest of Mazatlan, northward to at least southern Chihuahua, moving northwestward. The 11Z surface analysis showed a low over south-central QC, with cold front southwestward over Lake Ontario, southwestern OH, northern/western KY, north-central OK, to east-central NM. By 00Z the cold front should reach parts of ME, southeastern NY, northern VA, central AL, and southern OK, becoming a quasistationary to warm front over the TX Panhandle to northeastern NM. By the end of the period, this boundary should move offshore north of the Outer Banks of NC, and extend over central GA, southern AL/MS, the Red River Valley of TX/OK, and southeastern CO. Separate cyclogenesis should occur today over south-central/southeastern MT, with cold front southwestward across parts of the Great Basin. ...Northern/middle Atlantic Seaboard... Scattered thunderstorms -- mainly in lines but with some discrete activity -- are expected to move mostly eastward across this corridor from late morning through early evening in episodes, with damaging winds likely, a few embedded severe gusts possible, and isolated potential for large hail or a tornado. Low/middle-level destabilization will occur in the preconvective/ prefrontal environment throughout the day, essentially removing already weak MLCINH. This will occur via diurnal heating of the surface and large-scale lift ahead of the approaching Great Lakes trough aloft. Steepening boundary-layer lapse rates amid rich low-level moisture, with dewpoints commonly in the upper 60s to low 70s F, will offset modest mid/upper-level lapse rates enough to foster peak/preconvective MLCAPE in the 1500-2500 J/kg range. Greatest buoyancy is possible over the coastal plain between the Delmarva peninsula and eastern MA. Wind profiles will be largely unidirectional from the southwest or west-southwest, limiting low-level hodograph size and overall vertical shear. However, strengthening flow aloft with northward extent will support increasing potential for a few supercells northward from the northern Mid-Atlantic into New England, and especially across ME. A counterbalancing effect, however, will be diminishing buoyancy with northward extent over New England. Farther south over much of VA and NC, weak shear will support predominantly multicellular storm modes, with damaging/isolated severe gusts possible in water-loaded downdrafts. ...Northern Plains to central Rockies/High Plains... Scattered to isolated thunderstorms should develop over the central Rockies and higher terrain near the Four Corners and move northeastward to eastward this afternoon -- some of it out onto the central High Plains. Activity should produce locally strong-severe gusts and isolated large hail from downdrafts penetrating deep, well-mixed subcloud layers, though vertical shear this far south of the main flow belt should remain too weak to support well-organized severe potential. Farther north, however, a better-organized severe threat may occur this evening with later-developing convection in the northern Rockies and adjacent High Plains. Increasing large-scale ascent ahead of the Northwest trough will support this activity, along with backed low-level flow and strengthening convergence positioned poleward of the deepening surface low. Early-stage convection may include a few supercells with large hail and damaging gusts, with some convection potentially expanding upscale into one or more clusters as it encounters greater low-level moisture content across central/eastern MT. Large hail will remain possible -- especially with embedded supercell(s), and the severe-gust threat should increase with potential for mesobeta-scale cold-pool development, especially considering the moderately high LCL. A narrow corridor of mid 40s to mid 50s F surface dewpoints, and steep low/middle- level lapse rates, should support MLCAPE in the 1000-1500 J/kg range (locally/briefly higher). Veering winds with height will contribute to effective-shear magnitudes in the 45-55-kt range in support of storm organization. ...Central/southeastern AZ... Cloud debris and mostly light lingering precip are evident over southern AZ, related to the first perturbation, with warming IR cloud tops and overall thinning of clouds noted in recent satellite trends. This should continue and shift northwestward with the initial perturbation through midday into early afternoon, allowing for diurnal heating/destabilization of the boundary layer over southeastern AZ by mid/late afternoon. This, along with favorable low-level moisture, orographic forcing, and weak large-scale ascent preceding the next perturbation aloft, will support widely scattered to scattered afternoon thunderstorms, some of which may produce severe gusts. Valley-floor dewpoints in the 50s F largely should be maintained through the heating/mixing cycle, beneath very steep low-level lapse rates and a well-mixed subcloud layer. A deep southeasterly wind profile in low and middle levels will support northwestward motion of activity, which may aggregate their outflows to encourage both reinforcing development and localized channels of strong-severe wind. The somewhat delayed nature of the destabilization process, and uncertainties about storm coverage/aggregation, preclude greater unconditional probabilities at this time. ..Edwards/Kerr.. 06/30/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 AM CDT Sun Jun 30 2024 Valid 301300Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE I-95/NEAR-COASTAL CORRIDOR FROM THE DELAWARE VALLEY TO SOUTHEASTERN NEW ENGLAND...INCLUDING THE NEW YORK CITY METRO... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK FROM NORTHERN NORTH CAROLINA TO NEW ENGLAND...AND ALSO OVER PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered damaging winds will be possible across parts of the Northeast and Mid-Atlantic States this afternoon/evening. Hail and damaging winds may also occur from eastern Montana into western North Dakota. ...Synopsis... In mid/upper levels, the synoptic pattern over the CONUS will remain dominated by progressive troughs in the Northwest to northern Rockies, and in the Great Lakes to Northeast. An anticyclone aloft, attached to a more extensive, zonal, subtropical ridge, will remain anchored over the southern Plains. What will become the main shortwave perturbation associated with the Northeast trough is apparent over portions of the Upper Great Lakes and MI, and will amplify while moving over southern ON around 00Z. A sharp shortwave trough should result overnight, extending from northern VT across eastern NY to northern WV by 12Z tomorrow. Meanwhile, a series of minor/low-amplitude shortwaves and vorticity lobes will eject northeastward ahead of the Northwest trough, across the central/northern Rockies. A weak, convectively induced perturbation now near the southern AZ border should move slowly northwestward around the subtropical ridging. The northern part of another trough in the mid/upper easterlies is evident in moisture- channel imagery from the MX coastline northwest of Mazatlan, northward to at least southern Chihuahua, moving northwestward. The 11Z surface analysis showed a low over south-central QC, with cold front southwestward over Lake Ontario, southwestern OH, northern/western KY, north-central OK, to east-central NM. By 00Z the cold front should reach parts of ME, southeastern NY, northern VA, central AL, and southern OK, becoming a quasistationary to warm front over the TX Panhandle to northeastern NM. By the end of the period, this boundary should move offshore north of the Outer Banks of NC, and extend over central GA, southern AL/MS, the Red River Valley of TX/OK, and southeastern CO. Separate cyclogenesis should occur today over south-central/southeastern MT, with cold front southwestward across parts of the Great Basin. ...Northern/middle Atlantic Seaboard... Scattered thunderstorms -- mainly in lines but with some discrete activity -- are expected to move mostly eastward across this corridor from late morning through early evening in episodes, with damaging winds likely, a few embedded severe gusts possible, and isolated potential for large hail or a tornado. Low/middle-level destabilization will occur in the preconvective/ prefrontal environment throughout the day, essentially removing already weak MLCINH. This will occur via diurnal heating of the surface and large-scale lift ahead of the approaching Great Lakes trough aloft. Steepening boundary-layer lapse rates amid rich low-level moisture, with dewpoints commonly in the upper 60s to low 70s F, will offset modest mid/upper-level lapse rates enough to foster peak/preconvective MLCAPE in the 1500-2500 J/kg range. Greatest buoyancy is possible over the coastal plain between the Delmarva peninsula and eastern MA. Wind profiles will be largely unidirectional from the southwest or west-southwest, limiting low-level hodograph size and overall vertical shear. However, strengthening flow aloft with northward extent will support increasing potential for a few supercells northward from the northern Mid-Atlantic into New England, and especially across ME. A counterbalancing effect, however, will be diminishing buoyancy with northward extent over New England. Farther south over much of VA and NC, weak shear will support predominantly multicellular storm modes, with damaging/isolated severe gusts possible in water-loaded downdrafts. ...Northern Plains to central Rockies/High Plains... Scattered to isolated thunderstorms should develop over the central Rockies and higher terrain near the Four Corners and move northeastward to eastward this afternoon -- some of it out onto the central High Plains. Activity should produce locally strong-severe gusts and isolated large hail from downdrafts penetrating deep, well-mixed subcloud layers, though vertical shear this far south of the main flow belt should remain too weak to support well-organized severe potential. Farther north, however, a better-organized severe threat may occur this evening with later-developing convection in the northern Rockies and adjacent High Plains. Increasing large-scale ascent ahead of the Northwest trough will support this activity, along with backed low-level flow and strengthening convergence positioned poleward of the deepening surface low. Early-stage convection may include a few supercells with large hail and damaging gusts, with some convection potentially expanding upscale into one or more clusters as it encounters greater low-level moisture content across central/eastern MT. Large hail will remain possible -- especially with embedded supercell(s), and the severe-gust threat should increase with potential for mesobeta-scale cold-pool development, especially considering the moderately high LCL. A narrow corridor of mid 40s to mid 50s F surface dewpoints, and steep low/middle- level lapse rates, should support MLCAPE in the 1000-1500 J/kg range (locally/briefly higher). Veering winds with height will contribute to effective-shear magnitudes in the 45-55-kt range in support of storm organization. ...Central/southeastern AZ... Cloud debris and mostly light lingering precip are evident over southern AZ, related to the first perturbation, with warming IR cloud tops and overall thinning of clouds noted in recent satellite trends. This should continue and shift northwestward with the initial perturbation through midday into early afternoon, allowing for diurnal heating/destabilization of the boundary layer over southeastern AZ by mid/late afternoon. This, along with favorable low-level moisture, orographic forcing, and weak large-scale ascent preceding the next perturbation aloft, will support widely scattered to scattered afternoon thunderstorms, some of which may produce severe gusts. Valley-floor dewpoints in the 50s F largely should be maintained through the heating/mixing cycle, beneath very steep low-level lapse rates and a well-mixed subcloud layer. A deep southeasterly wind profile in low and middle levels will support northwestward motion of activity, which may aggregate their outflows to encourage both reinforcing development and localized channels of strong-severe wind. The somewhat delayed nature of the destabilization process, and uncertainties about storm coverage/aggregation, preclude greater unconditional probabilities at this time. ..Edwards/Kerr.. 06/30/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 AM CDT Sun Jun 30 2024 Valid 301300Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE I-95/NEAR-COASTAL CORRIDOR FROM THE DELAWARE VALLEY TO SOUTHEASTERN NEW ENGLAND...INCLUDING THE NEW YORK CITY METRO... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK FROM NORTHERN NORTH CAROLINA TO NEW ENGLAND...AND ALSO OVER PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered damaging winds will be possible across parts of the Northeast and Mid-Atlantic States this afternoon/evening. Hail and damaging winds may also occur from eastern Montana into western North Dakota. ...Synopsis... In mid/upper levels, the synoptic pattern over the CONUS will remain dominated by progressive troughs in the Northwest to northern Rockies, and in the Great Lakes to Northeast. An anticyclone aloft, attached to a more extensive, zonal, subtropical ridge, will remain anchored over the southern Plains. What will become the main shortwave perturbation associated with the Northeast trough is apparent over portions of the Upper Great Lakes and MI, and will amplify while moving over southern ON around 00Z. A sharp shortwave trough should result overnight, extending from northern VT across eastern NY to northern WV by 12Z tomorrow. Meanwhile, a series of minor/low-amplitude shortwaves and vorticity lobes will eject northeastward ahead of the Northwest trough, across the central/northern Rockies. A weak, convectively induced perturbation now near the southern AZ border should move slowly northwestward around the subtropical ridging. The northern part of another trough in the mid/upper easterlies is evident in moisture- channel imagery from the MX coastline northwest of Mazatlan, northward to at least southern Chihuahua, moving northwestward. The 11Z surface analysis showed a low over south-central QC, with cold front southwestward over Lake Ontario, southwestern OH, northern/western KY, north-central OK, to east-central NM. By 00Z the cold front should reach parts of ME, southeastern NY, northern VA, central AL, and southern OK, becoming a quasistationary to warm front over the TX Panhandle to northeastern NM. By the end of the period, this boundary should move offshore north of the Outer Banks of NC, and extend over central GA, southern AL/MS, the Red River Valley of TX/OK, and southeastern CO. Separate cyclogenesis should occur today over south-central/southeastern MT, with cold front southwestward across parts of the Great Basin. ...Northern/middle Atlantic Seaboard... Scattered thunderstorms -- mainly in lines but with some discrete activity -- are expected to move mostly eastward across this corridor from late morning through early evening in episodes, with damaging winds likely, a few embedded severe gusts possible, and isolated potential for large hail or a tornado. Low/middle-level destabilization will occur in the preconvective/ prefrontal environment throughout the day, essentially removing already weak MLCINH. This will occur via diurnal heating of the surface and large-scale lift ahead of the approaching Great Lakes trough aloft. Steepening boundary-layer lapse rates amid rich low-level moisture, with dewpoints commonly in the upper 60s to low 70s F, will offset modest mid/upper-level lapse rates enough to foster peak/preconvective MLCAPE in the 1500-2500 J/kg range. Greatest buoyancy is possible over the coastal plain between the Delmarva peninsula and eastern MA. Wind profiles will be largely unidirectional from the southwest or west-southwest, limiting low-level hodograph size and overall vertical shear. However, strengthening flow aloft with northward extent will support increasing potential for a few supercells northward from the northern Mid-Atlantic into New England, and especially across ME. A counterbalancing effect, however, will be diminishing buoyancy with northward extent over New England. Farther south over much of VA and NC, weak shear will support predominantly multicellular storm modes, with damaging/isolated severe gusts possible in water-loaded downdrafts. ...Northern Plains to central Rockies/High Plains... Scattered to isolated thunderstorms should develop over the central Rockies and higher terrain near the Four Corners and move northeastward to eastward this afternoon -- some of it out onto the central High Plains. Activity should produce locally strong-severe gusts and isolated large hail from downdrafts penetrating deep, well-mixed subcloud layers, though vertical shear this far south of the main flow belt should remain too weak to support well-organized severe potential. Farther north, however, a better-organized severe threat may occur this evening with later-developing convection in the northern Rockies and adjacent High Plains. Increasing large-scale ascent ahead of the Northwest trough will support this activity, along with backed low-level flow and strengthening convergence positioned poleward of the deepening surface low. Early-stage convection may include a few supercells with large hail and damaging gusts, with some convection potentially expanding upscale into one or more clusters as it encounters greater low-level moisture content across central/eastern MT. Large hail will remain possible -- especially with embedded supercell(s), and the severe-gust threat should increase with potential for mesobeta-scale cold-pool development, especially considering the moderately high LCL. A narrow corridor of mid 40s to mid 50s F surface dewpoints, and steep low/middle- level lapse rates, should support MLCAPE in the 1000-1500 J/kg range (locally/briefly higher). Veering winds with height will contribute to effective-shear magnitudes in the 45-55-kt range in support of storm organization. ...Central/southeastern AZ... Cloud debris and mostly light lingering precip are evident over southern AZ, related to the first perturbation, with warming IR cloud tops and overall thinning of clouds noted in recent satellite trends. This should continue and shift northwestward with the initial perturbation through midday into early afternoon, allowing for diurnal heating/destabilization of the boundary layer over southeastern AZ by mid/late afternoon. This, along with favorable low-level moisture, orographic forcing, and weak large-scale ascent preceding the next perturbation aloft, will support widely scattered to scattered afternoon thunderstorms, some of which may produce severe gusts. Valley-floor dewpoints in the 50s F largely should be maintained through the heating/mixing cycle, beneath very steep low-level lapse rates and a well-mixed subcloud layer. A deep southeasterly wind profile in low and middle levels will support northwestward motion of activity, which may aggregate their outflows to encourage both reinforcing development and localized channels of strong-severe wind. The somewhat delayed nature of the destabilization process, and uncertainties about storm coverage/aggregation, preclude greater unconditional probabilities at this time. ..Edwards/Kerr.. 06/30/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 AM CDT Sun Jun 30 2024 Valid 301300Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE I-95/NEAR-COASTAL CORRIDOR FROM THE DELAWARE VALLEY TO SOUTHEASTERN NEW ENGLAND...INCLUDING THE NEW YORK CITY METRO... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK FROM NORTHERN NORTH CAROLINA TO NEW ENGLAND...AND ALSO OVER PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered damaging winds will be possible across parts of the Northeast and Mid-Atlantic States this afternoon/evening. Hail and damaging winds may also occur from eastern Montana into western North Dakota. ...Synopsis... In mid/upper levels, the synoptic pattern over the CONUS will remain dominated by progressive troughs in the Northwest to northern Rockies, and in the Great Lakes to Northeast. An anticyclone aloft, attached to a more extensive, zonal, subtropical ridge, will remain anchored over the southern Plains. What will become the main shortwave perturbation associated with the Northeast trough is apparent over portions of the Upper Great Lakes and MI, and will amplify while moving over southern ON around 00Z. A sharp shortwave trough should result overnight, extending from northern VT across eastern NY to northern WV by 12Z tomorrow. Meanwhile, a series of minor/low-amplitude shortwaves and vorticity lobes will eject northeastward ahead of the Northwest trough, across the central/northern Rockies. A weak, convectively induced perturbation now near the southern AZ border should move slowly northwestward around the subtropical ridging. The northern part of another trough in the mid/upper easterlies is evident in moisture- channel imagery from the MX coastline northwest of Mazatlan, northward to at least southern Chihuahua, moving northwestward. The 11Z surface analysis showed a low over south-central QC, with cold front southwestward over Lake Ontario, southwestern OH, northern/western KY, north-central OK, to east-central NM. By 00Z the cold front should reach parts of ME, southeastern NY, northern VA, central AL, and southern OK, becoming a quasistationary to warm front over the TX Panhandle to northeastern NM. By the end of the period, this boundary should move offshore north of the Outer Banks of NC, and extend over central GA, southern AL/MS, the Red River Valley of TX/OK, and southeastern CO. Separate cyclogenesis should occur today over south-central/southeastern MT, with cold front southwestward across parts of the Great Basin. ...Northern/middle Atlantic Seaboard... Scattered thunderstorms -- mainly in lines but with some discrete activity -- are expected to move mostly eastward across this corridor from late morning through early evening in episodes, with damaging winds likely, a few embedded severe gusts possible, and isolated potential for large hail or a tornado. Low/middle-level destabilization will occur in the preconvective/ prefrontal environment throughout the day, essentially removing already weak MLCINH. This will occur via diurnal heating of the surface and large-scale lift ahead of the approaching Great Lakes trough aloft. Steepening boundary-layer lapse rates amid rich low-level moisture, with dewpoints commonly in the upper 60s to low 70s F, will offset modest mid/upper-level lapse rates enough to foster peak/preconvective MLCAPE in the 1500-2500 J/kg range. Greatest buoyancy is possible over the coastal plain between the Delmarva peninsula and eastern MA. Wind profiles will be largely unidirectional from the southwest or west-southwest, limiting low-level hodograph size and overall vertical shear. However, strengthening flow aloft with northward extent will support increasing potential for a few supercells northward from the northern Mid-Atlantic into New England, and especially across ME. A counterbalancing effect, however, will be diminishing buoyancy with northward extent over New England. Farther south over much of VA and NC, weak shear will support predominantly multicellular storm modes, with damaging/isolated severe gusts possible in water-loaded downdrafts. ...Northern Plains to central Rockies/High Plains... Scattered to isolated thunderstorms should develop over the central Rockies and higher terrain near the Four Corners and move northeastward to eastward this afternoon -- some of it out onto the central High Plains. Activity should produce locally strong-severe gusts and isolated large hail from downdrafts penetrating deep, well-mixed subcloud layers, though vertical shear this far south of the main flow belt should remain too weak to support well-organized severe potential. Farther north, however, a better-organized severe threat may occur this evening with later-developing convection in the northern Rockies and adjacent High Plains. Increasing large-scale ascent ahead of the Northwest trough will support this activity, along with backed low-level flow and strengthening convergence positioned poleward of the deepening surface low. Early-stage convection may include a few supercells with large hail and damaging gusts, with some convection potentially expanding upscale into one or more clusters as it encounters greater low-level moisture content across central/eastern MT. Large hail will remain possible -- especially with embedded supercell(s), and the severe-gust threat should increase with potential for mesobeta-scale cold-pool development, especially considering the moderately high LCL. A narrow corridor of mid 40s to mid 50s F surface dewpoints, and steep low/middle- level lapse rates, should support MLCAPE in the 1000-1500 J/kg range (locally/briefly higher). Veering winds with height will contribute to effective-shear magnitudes in the 45-55-kt range in support of storm organization. ...Central/southeastern AZ... Cloud debris and mostly light lingering precip are evident over southern AZ, related to the first perturbation, with warming IR cloud tops and overall thinning of clouds noted in recent satellite trends. This should continue and shift northwestward with the initial perturbation through midday into early afternoon, allowing for diurnal heating/destabilization of the boundary layer over southeastern AZ by mid/late afternoon. This, along with favorable low-level moisture, orographic forcing, and weak large-scale ascent preceding the next perturbation aloft, will support widely scattered to scattered afternoon thunderstorms, some of which may produce severe gusts. Valley-floor dewpoints in the 50s F largely should be maintained through the heating/mixing cycle, beneath very steep low-level lapse rates and a well-mixed subcloud layer. A deep southeasterly wind profile in low and middle levels will support northwestward motion of activity, which may aggregate their outflows to encourage both reinforcing development and localized channels of strong-severe wind. The somewhat delayed nature of the destabilization process, and uncertainties about storm coverage/aggregation, preclude greater unconditional probabilities at this time. ..Edwards/Kerr.. 06/30/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 AM CDT Sun Jun 30 2024 Valid 301300Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE I-95/NEAR-COASTAL CORRIDOR FROM THE DELAWARE VALLEY TO SOUTHEASTERN NEW ENGLAND...INCLUDING THE NEW YORK CITY METRO... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK FROM NORTHERN NORTH CAROLINA TO NEW ENGLAND...AND ALSO OVER PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered damaging winds will be possible across parts of the Northeast and Mid-Atlantic States this afternoon/evening. Hail and damaging winds may also occur from eastern Montana into western North Dakota. ...Synopsis... In mid/upper levels, the synoptic pattern over the CONUS will remain dominated by progressive troughs in the Northwest to northern Rockies, and in the Great Lakes to Northeast. An anticyclone aloft, attached to a more extensive, zonal, subtropical ridge, will remain anchored over the southern Plains. What will become the main shortwave perturbation associated with the Northeast trough is apparent over portions of the Upper Great Lakes and MI, and will amplify while moving over southern ON around 00Z. A sharp shortwave trough should result overnight, extending from northern VT across eastern NY to northern WV by 12Z tomorrow. Meanwhile, a series of minor/low-amplitude shortwaves and vorticity lobes will eject northeastward ahead of the Northwest trough, across the central/northern Rockies. A weak, convectively induced perturbation now near the southern AZ border should move slowly northwestward around the subtropical ridging. The northern part of another trough in the mid/upper easterlies is evident in moisture- channel imagery from the MX coastline northwest of Mazatlan, northward to at least southern Chihuahua, moving northwestward. The 11Z surface analysis showed a low over south-central QC, with cold front southwestward over Lake Ontario, southwestern OH, northern/western KY, north-central OK, to east-central NM. By 00Z the cold front should reach parts of ME, southeastern NY, northern VA, central AL, and southern OK, becoming a quasistationary to warm front over the TX Panhandle to northeastern NM. By the end of the period, this boundary should move offshore north of the Outer Banks of NC, and extend over central GA, southern AL/MS, the Red River Valley of TX/OK, and southeastern CO. Separate cyclogenesis should occur today over south-central/southeastern MT, with cold front southwestward across parts of the Great Basin. ...Northern/middle Atlantic Seaboard... Scattered thunderstorms -- mainly in lines but with some discrete activity -- are expected to move mostly eastward across this corridor from late morning through early evening in episodes, with damaging winds likely, a few embedded severe gusts possible, and isolated potential for large hail or a tornado. Low/middle-level destabilization will occur in the preconvective/ prefrontal environment throughout the day, essentially removing already weak MLCINH. This will occur via diurnal heating of the surface and large-scale lift ahead of the approaching Great Lakes trough aloft. Steepening boundary-layer lapse rates amid rich low-level moisture, with dewpoints commonly in the upper 60s to low 70s F, will offset modest mid/upper-level lapse rates enough to foster peak/preconvective MLCAPE in the 1500-2500 J/kg range. Greatest buoyancy is possible over the coastal plain between the Delmarva peninsula and eastern MA. Wind profiles will be largely unidirectional from the southwest or west-southwest, limiting low-level hodograph size and overall vertical shear. However, strengthening flow aloft with northward extent will support increasing potential for a few supercells northward from the northern Mid-Atlantic into New England, and especially across ME. A counterbalancing effect, however, will be diminishing buoyancy with northward extent over New England. Farther south over much of VA and NC, weak shear will support predominantly multicellular storm modes, with damaging/isolated severe gusts possible in water-loaded downdrafts. ...Northern Plains to central Rockies/High Plains... Scattered to isolated thunderstorms should develop over the central Rockies and higher terrain near the Four Corners and move northeastward to eastward this afternoon -- some of it out onto the central High Plains. Activity should produce locally strong-severe gusts and isolated large hail from downdrafts penetrating deep, well-mixed subcloud layers, though vertical shear this far south of the main flow belt should remain too weak to support well-organized severe potential. Farther north, however, a better-organized severe threat may occur this evening with later-developing convection in the northern Rockies and adjacent High Plains. Increasing large-scale ascent ahead of the Northwest trough will support this activity, along with backed low-level flow and strengthening convergence positioned poleward of the deepening surface low. Early-stage convection may include a few supercells with large hail and damaging gusts, with some convection potentially expanding upscale into one or more clusters as it encounters greater low-level moisture content across central/eastern MT. Large hail will remain possible -- especially with embedded supercell(s), and the severe-gust threat should increase with potential for mesobeta-scale cold-pool development, especially considering the moderately high LCL. A narrow corridor of mid 40s to mid 50s F surface dewpoints, and steep low/middle- level lapse rates, should support MLCAPE in the 1000-1500 J/kg range (locally/briefly higher). Veering winds with height will contribute to effective-shear magnitudes in the 45-55-kt range in support of storm organization. ...Central/southeastern AZ... Cloud debris and mostly light lingering precip are evident over southern AZ, related to the first perturbation, with warming IR cloud tops and overall thinning of clouds noted in recent satellite trends. This should continue and shift northwestward with the initial perturbation through midday into early afternoon, allowing for diurnal heating/destabilization of the boundary layer over southeastern AZ by mid/late afternoon. This, along with favorable low-level moisture, orographic forcing, and weak large-scale ascent preceding the next perturbation aloft, will support widely scattered to scattered afternoon thunderstorms, some of which may produce severe gusts. Valley-floor dewpoints in the 50s F largely should be maintained through the heating/mixing cycle, beneath very steep low-level lapse rates and a well-mixed subcloud layer. A deep southeasterly wind profile in low and middle levels will support northwestward motion of activity, which may aggregate their outflows to encourage both reinforcing development and localized channels of strong-severe wind. The somewhat delayed nature of the destabilization process, and uncertainties about storm coverage/aggregation, preclude greater unconditional probabilities at this time. ..Edwards/Kerr.. 06/30/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 AM CDT Sun Jun 30 2024 Valid 301300Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE I-95/NEAR-COASTAL CORRIDOR FROM THE DELAWARE VALLEY TO SOUTHEASTERN NEW ENGLAND...INCLUDING THE NEW YORK CITY METRO... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK FROM NORTHERN NORTH CAROLINA TO NEW ENGLAND...AND ALSO OVER PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered damaging winds will be possible across parts of the Northeast and Mid-Atlantic States this afternoon/evening. Hail and damaging winds may also occur from eastern Montana into western North Dakota. ...Synopsis... In mid/upper levels, the synoptic pattern over the CONUS will remain dominated by progressive troughs in the Northwest to northern Rockies, and in the Great Lakes to Northeast. An anticyclone aloft, attached to a more extensive, zonal, subtropical ridge, will remain anchored over the southern Plains. What will become the main shortwave perturbation associated with the Northeast trough is apparent over portions of the Upper Great Lakes and MI, and will amplify while moving over southern ON around 00Z. A sharp shortwave trough should result overnight, extending from northern VT across eastern NY to northern WV by 12Z tomorrow. Meanwhile, a series of minor/low-amplitude shortwaves and vorticity lobes will eject northeastward ahead of the Northwest trough, across the central/northern Rockies. A weak, convectively induced perturbation now near the southern AZ border should move slowly northwestward around the subtropical ridging. The northern part of another trough in the mid/upper easterlies is evident in moisture- channel imagery from the MX coastline northwest of Mazatlan, northward to at least southern Chihuahua, moving northwestward. The 11Z surface analysis showed a low over south-central QC, with cold front southwestward over Lake Ontario, southwestern OH, northern/western KY, north-central OK, to east-central NM. By 00Z the cold front should reach parts of ME, southeastern NY, northern VA, central AL, and southern OK, becoming a quasistationary to warm front over the TX Panhandle to northeastern NM. By the end of the period, this boundary should move offshore north of the Outer Banks of NC, and extend over central GA, southern AL/MS, the Red River Valley of TX/OK, and southeastern CO. Separate cyclogenesis should occur today over south-central/southeastern MT, with cold front southwestward across parts of the Great Basin. ...Northern/middle Atlantic Seaboard... Scattered thunderstorms -- mainly in lines but with some discrete activity -- are expected to move mostly eastward across this corridor from late morning through early evening in episodes, with damaging winds likely, a few embedded severe gusts possible, and isolated potential for large hail or a tornado. Low/middle-level destabilization will occur in the preconvective/ prefrontal environment throughout the day, essentially removing already weak MLCINH. This will occur via diurnal heating of the surface and large-scale lift ahead of the approaching Great Lakes trough aloft. Steepening boundary-layer lapse rates amid rich low-level moisture, with dewpoints commonly in the upper 60s to low 70s F, will offset modest mid/upper-level lapse rates enough to foster peak/preconvective MLCAPE in the 1500-2500 J/kg range. Greatest buoyancy is possible over the coastal plain between the Delmarva peninsula and eastern MA. Wind profiles will be largely unidirectional from the southwest or west-southwest, limiting low-level hodograph size and overall vertical shear. However, strengthening flow aloft with northward extent will support increasing potential for a few supercells northward from the northern Mid-Atlantic into New England, and especially across ME. A counterbalancing effect, however, will be diminishing buoyancy with northward extent over New England. Farther south over much of VA and NC, weak shear will support predominantly multicellular storm modes, with damaging/isolated severe gusts possible in water-loaded downdrafts. ...Northern Plains to central Rockies/High Plains... Scattered to isolated thunderstorms should develop over the central Rockies and higher terrain near the Four Corners and move northeastward to eastward this afternoon -- some of it out onto the central High Plains. Activity should produce locally strong-severe gusts and isolated large hail from downdrafts penetrating deep, well-mixed subcloud layers, though vertical shear this far south of the main flow belt should remain too weak to support well-organized severe potential. Farther north, however, a better-organized severe threat may occur this evening with later-developing convection in the northern Rockies and adjacent High Plains. Increasing large-scale ascent ahead of the Northwest trough will support this activity, along with backed low-level flow and strengthening convergence positioned poleward of the deepening surface low. Early-stage convection may include a few supercells with large hail and damaging gusts, with some convection potentially expanding upscale into one or more clusters as it encounters greater low-level moisture content across central/eastern MT. Large hail will remain possible -- especially with embedded supercell(s), and the severe-gust threat should increase with potential for mesobeta-scale cold-pool development, especially considering the moderately high LCL. A narrow corridor of mid 40s to mid 50s F surface dewpoints, and steep low/middle- level lapse rates, should support MLCAPE in the 1000-1500 J/kg range (locally/briefly higher). Veering winds with height will contribute to effective-shear magnitudes in the 45-55-kt range in support of storm organization. ...Central/southeastern AZ... Cloud debris and mostly light lingering precip are evident over southern AZ, related to the first perturbation, with warming IR cloud tops and overall thinning of clouds noted in recent satellite trends. This should continue and shift northwestward with the initial perturbation through midday into early afternoon, allowing for diurnal heating/destabilization of the boundary layer over southeastern AZ by mid/late afternoon. This, along with favorable low-level moisture, orographic forcing, and weak large-scale ascent preceding the next perturbation aloft, will support widely scattered to scattered afternoon thunderstorms, some of which may produce severe gusts. Valley-floor dewpoints in the 50s F largely should be maintained through the heating/mixing cycle, beneath very steep low-level lapse rates and a well-mixed subcloud layer. A deep southeasterly wind profile in low and middle levels will support northwestward motion of activity, which may aggregate their outflows to encourage both reinforcing development and localized channels of strong-severe wind. The somewhat delayed nature of the destabilization process, and uncertainties about storm coverage/aggregation, preclude greater unconditional probabilities at this time. ..Edwards/Kerr.. 06/30/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 AM CDT Sun Jun 30 2024 Valid 301300Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE I-95/NEAR-COASTAL CORRIDOR FROM THE DELAWARE VALLEY TO SOUTHEASTERN NEW ENGLAND...INCLUDING THE NEW YORK CITY METRO... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK FROM NORTHERN NORTH CAROLINA TO NEW ENGLAND...AND ALSO OVER PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered damaging winds will be possible across parts of the Northeast and Mid-Atlantic States this afternoon/evening. Hail and damaging winds may also occur from eastern Montana into western North Dakota. ...Synopsis... In mid/upper levels, the synoptic pattern over the CONUS will remain dominated by progressive troughs in the Northwest to northern Rockies, and in the Great Lakes to Northeast. An anticyclone aloft, attached to a more extensive, zonal, subtropical ridge, will remain anchored over the southern Plains. What will become the main shortwave perturbation associated with the Northeast trough is apparent over portions of the Upper Great Lakes and MI, and will amplify while moving over southern ON around 00Z. A sharp shortwave trough should result overnight, extending from northern VT across eastern NY to northern WV by 12Z tomorrow. Meanwhile, a series of minor/low-amplitude shortwaves and vorticity lobes will eject northeastward ahead of the Northwest trough, across the central/northern Rockies. A weak, convectively induced perturbation now near the southern AZ border should move slowly northwestward around the subtropical ridging. The northern part of another trough in the mid/upper easterlies is evident in moisture- channel imagery from the MX coastline northwest of Mazatlan, northward to at least southern Chihuahua, moving northwestward. The 11Z surface analysis showed a low over south-central QC, with cold front southwestward over Lake Ontario, southwestern OH, northern/western KY, north-central OK, to east-central NM. By 00Z the cold front should reach parts of ME, southeastern NY, northern VA, central AL, and southern OK, becoming a quasistationary to warm front over the TX Panhandle to northeastern NM. By the end of the period, this boundary should move offshore north of the Outer Banks of NC, and extend over central GA, southern AL/MS, the Red River Valley of TX/OK, and southeastern CO. Separate cyclogenesis should occur today over south-central/southeastern MT, with cold front southwestward across parts of the Great Basin. ...Northern/middle Atlantic Seaboard... Scattered thunderstorms -- mainly in lines but with some discrete activity -- are expected to move mostly eastward across this corridor from late morning through early evening in episodes, with damaging winds likely, a few embedded severe gusts possible, and isolated potential for large hail or a tornado. Low/middle-level destabilization will occur in the preconvective/ prefrontal environment throughout the day, essentially removing already weak MLCINH. This will occur via diurnal heating of the surface and large-scale lift ahead of the approaching Great Lakes trough aloft. Steepening boundary-layer lapse rates amid rich low-level moisture, with dewpoints commonly in the upper 60s to low 70s F, will offset modest mid/upper-level lapse rates enough to foster peak/preconvective MLCAPE in the 1500-2500 J/kg range. Greatest buoyancy is possible over the coastal plain between the Delmarva peninsula and eastern MA. Wind profiles will be largely unidirectional from the southwest or west-southwest, limiting low-level hodograph size and overall vertical shear. However, strengthening flow aloft with northward extent will support increasing potential for a few supercells northward from the northern Mid-Atlantic into New England, and especially across ME. A counterbalancing effect, however, will be diminishing buoyancy with northward extent over New England. Farther south over much of VA and NC, weak shear will support predominantly multicellular storm modes, with damaging/isolated severe gusts possible in water-loaded downdrafts. ...Northern Plains to central Rockies/High Plains... Scattered to isolated thunderstorms should develop over the central Rockies and higher terrain near the Four Corners and move northeastward to eastward this afternoon -- some of it out onto the central High Plains. Activity should produce locally strong-severe gusts and isolated large hail from downdrafts penetrating deep, well-mixed subcloud layers, though vertical shear this far south of the main flow belt should remain too weak to support well-organized severe potential. Farther north, however, a better-organized severe threat may occur this evening with later-developing convection in the northern Rockies and adjacent High Plains. Increasing large-scale ascent ahead of the Northwest trough will support this activity, along with backed low-level flow and strengthening convergence positioned poleward of the deepening surface low. Early-stage convection may include a few supercells with large hail and damaging gusts, with some convection potentially expanding upscale into one or more clusters as it encounters greater low-level moisture content across central/eastern MT. Large hail will remain possible -- especially with embedded supercell(s), and the severe-gust threat should increase with potential for mesobeta-scale cold-pool development, especially considering the moderately high LCL. A narrow corridor of mid 40s to mid 50s F surface dewpoints, and steep low/middle- level lapse rates, should support MLCAPE in the 1000-1500 J/kg range (locally/briefly higher). Veering winds with height will contribute to effective-shear magnitudes in the 45-55-kt range in support of storm organization. ...Central/southeastern AZ... Cloud debris and mostly light lingering precip are evident over southern AZ, related to the first perturbation, with warming IR cloud tops and overall thinning of clouds noted in recent satellite trends. This should continue and shift northwestward with the initial perturbation through midday into early afternoon, allowing for diurnal heating/destabilization of the boundary layer over southeastern AZ by mid/late afternoon. This, along with favorable low-level moisture, orographic forcing, and weak large-scale ascent preceding the next perturbation aloft, will support widely scattered to scattered afternoon thunderstorms, some of which may produce severe gusts. Valley-floor dewpoints in the 50s F largely should be maintained through the heating/mixing cycle, beneath very steep low-level lapse rates and a well-mixed subcloud layer. A deep southeasterly wind profile in low and middle levels will support northwestward motion of activity, which may aggregate their outflows to encourage both reinforcing development and localized channels of strong-severe wind. The somewhat delayed nature of the destabilization process, and uncertainties about storm coverage/aggregation, preclude greater unconditional probabilities at this time. ..Edwards/Kerr.. 06/30/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 AM CDT Sun Jun 30 2024 Valid 301300Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE I-95/NEAR-COASTAL CORRIDOR FROM THE DELAWARE VALLEY TO SOUTHEASTERN NEW ENGLAND...INCLUDING THE NEW YORK CITY METRO... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK FROM NORTHERN NORTH CAROLINA TO NEW ENGLAND...AND ALSO OVER PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered damaging winds will be possible across parts of the Northeast and Mid-Atlantic States this afternoon/evening. Hail and damaging winds may also occur from eastern Montana into western North Dakota. ...Synopsis... In mid/upper levels, the synoptic pattern over the CONUS will remain dominated by progressive troughs in the Northwest to northern Rockies, and in the Great Lakes to Northeast. An anticyclone aloft, attached to a more extensive, zonal, subtropical ridge, will remain anchored over the southern Plains. What will become the main shortwave perturbation associated with the Northeast trough is apparent over portions of the Upper Great Lakes and MI, and will amplify while moving over southern ON around 00Z. A sharp shortwave trough should result overnight, extending from northern VT across eastern NY to northern WV by 12Z tomorrow. Meanwhile, a series of minor/low-amplitude shortwaves and vorticity lobes will eject northeastward ahead of the Northwest trough, across the central/northern Rockies. A weak, convectively induced perturbation now near the southern AZ border should move slowly northwestward around the subtropical ridging. The northern part of another trough in the mid/upper easterlies is evident in moisture- channel imagery from the MX coastline northwest of Mazatlan, northward to at least southern Chihuahua, moving northwestward. The 11Z surface analysis showed a low over south-central QC, with cold front southwestward over Lake Ontario, southwestern OH, northern/western KY, north-central OK, to east-central NM. By 00Z the cold front should reach parts of ME, southeastern NY, northern VA, central AL, and southern OK, becoming a quasistationary to warm front over the TX Panhandle to northeastern NM. By the end of the period, this boundary should move offshore north of the Outer Banks of NC, and extend over central GA, southern AL/MS, the Red River Valley of TX/OK, and southeastern CO. Separate cyclogenesis should occur today over south-central/southeastern MT, with cold front southwestward across parts of the Great Basin. ...Northern/middle Atlantic Seaboard... Scattered thunderstorms -- mainly in lines but with some discrete activity -- are expected to move mostly eastward across this corridor from late morning through early evening in episodes, with damaging winds likely, a few embedded severe gusts possible, and isolated potential for large hail or a tornado. Low/middle-level destabilization will occur in the preconvective/ prefrontal environment throughout the day, essentially removing already weak MLCINH. This will occur via diurnal heating of the surface and large-scale lift ahead of the approaching Great Lakes trough aloft. Steepening boundary-layer lapse rates amid rich low-level moisture, with dewpoints commonly in the upper 60s to low 70s F, will offset modest mid/upper-level lapse rates enough to foster peak/preconvective MLCAPE in the 1500-2500 J/kg range. Greatest buoyancy is possible over the coastal plain between the Delmarva peninsula and eastern MA. Wind profiles will be largely unidirectional from the southwest or west-southwest, limiting low-level hodograph size and overall vertical shear. However, strengthening flow aloft with northward extent will support increasing potential for a few supercells northward from the northern Mid-Atlantic into New England, and especially across ME. A counterbalancing effect, however, will be diminishing buoyancy with northward extent over New England. Farther south over much of VA and NC, weak shear will support predominantly multicellular storm modes, with damaging/isolated severe gusts possible in water-loaded downdrafts. ...Northern Plains to central Rockies/High Plains... Scattered to isolated thunderstorms should develop over the central Rockies and higher terrain near the Four Corners and move northeastward to eastward this afternoon -- some of it out onto the central High Plains. Activity should produce locally strong-severe gusts and isolated large hail from downdrafts penetrating deep, well-mixed subcloud layers, though vertical shear this far south of the main flow belt should remain too weak to support well-organized severe potential. Farther north, however, a better-organized severe threat may occur this evening with later-developing convection in the northern Rockies and adjacent High Plains. Increasing large-scale ascent ahead of the Northwest trough will support this activity, along with backed low-level flow and strengthening convergence positioned poleward of the deepening surface low. Early-stage convection may include a few supercells with large hail and damaging gusts, with some convection potentially expanding upscale into one or more clusters as it encounters greater low-level moisture content across central/eastern MT. Large hail will remain possible -- especially with embedded supercell(s), and the severe-gust threat should increase with potential for mesobeta-scale cold-pool development, especially considering the moderately high LCL. A narrow corridor of mid 40s to mid 50s F surface dewpoints, and steep low/middle- level lapse rates, should support MLCAPE in the 1000-1500 J/kg range (locally/briefly higher). Veering winds with height will contribute to effective-shear magnitudes in the 45-55-kt range in support of storm organization. ...Central/southeastern AZ... Cloud debris and mostly light lingering precip are evident over southern AZ, related to the first perturbation, with warming IR cloud tops and overall thinning of clouds noted in recent satellite trends. This should continue and shift northwestward with the initial perturbation through midday into early afternoon, allowing for diurnal heating/destabilization of the boundary layer over southeastern AZ by mid/late afternoon. This, along with favorable low-level moisture, orographic forcing, and weak large-scale ascent preceding the next perturbation aloft, will support widely scattered to scattered afternoon thunderstorms, some of which may produce severe gusts. Valley-floor dewpoints in the 50s F largely should be maintained through the heating/mixing cycle, beneath very steep low-level lapse rates and a well-mixed subcloud layer. A deep southeasterly wind profile in low and middle levels will support northwestward motion of activity, which may aggregate their outflows to encourage both reinforcing development and localized channels of strong-severe wind. The somewhat delayed nature of the destabilization process, and uncertainties about storm coverage/aggregation, preclude greater unconditional probabilities at this time. ..Edwards/Kerr.. 06/30/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 AM CDT Sun Jun 30 2024 Valid 301300Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE I-95/NEAR-COASTAL CORRIDOR FROM THE DELAWARE VALLEY TO SOUTHEASTERN NEW ENGLAND...INCLUDING THE NEW YORK CITY METRO... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK FROM NORTHERN NORTH CAROLINA TO NEW ENGLAND...AND ALSO OVER PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered damaging winds will be possible across parts of the Northeast and Mid-Atlantic States this afternoon/evening. Hail and damaging winds may also occur from eastern Montana into western North Dakota. ...Synopsis... In mid/upper levels, the synoptic pattern over the CONUS will remain dominated by progressive troughs in the Northwest to northern Rockies, and in the Great Lakes to Northeast. An anticyclone aloft, attached to a more extensive, zonal, subtropical ridge, will remain anchored over the southern Plains. What will become the main shortwave perturbation associated with the Northeast trough is apparent over portions of the Upper Great Lakes and MI, and will amplify while moving over southern ON around 00Z. A sharp shortwave trough should result overnight, extending from northern VT across eastern NY to northern WV by 12Z tomorrow. Meanwhile, a series of minor/low-amplitude shortwaves and vorticity lobes will eject northeastward ahead of the Northwest trough, across the central/northern Rockies. A weak, convectively induced perturbation now near the southern AZ border should move slowly northwestward around the subtropical ridging. The northern part of another trough in the mid/upper easterlies is evident in moisture- channel imagery from the MX coastline northwest of Mazatlan, northward to at least southern Chihuahua, moving northwestward. The 11Z surface analysis showed a low over south-central QC, with cold front southwestward over Lake Ontario, southwestern OH, northern/western KY, north-central OK, to east-central NM. By 00Z the cold front should reach parts of ME, southeastern NY, northern VA, central AL, and southern OK, becoming a quasistationary to warm front over the TX Panhandle to northeastern NM. By the end of the period, this boundary should move offshore north of the Outer Banks of NC, and extend over central GA, southern AL/MS, the Red River Valley of TX/OK, and southeastern CO. Separate cyclogenesis should occur today over south-central/southeastern MT, with cold front southwestward across parts of the Great Basin. ...Northern/middle Atlantic Seaboard... Scattered thunderstorms -- mainly in lines but with some discrete activity -- are expected to move mostly eastward across this corridor from late morning through early evening in episodes, with damaging winds likely, a few embedded severe gusts possible, and isolated potential for large hail or a tornado. Low/middle-level destabilization will occur in the preconvective/ prefrontal environment throughout the day, essentially removing already weak MLCINH. This will occur via diurnal heating of the surface and large-scale lift ahead of the approaching Great Lakes trough aloft. Steepening boundary-layer lapse rates amid rich low-level moisture, with dewpoints commonly in the upper 60s to low 70s F, will offset modest mid/upper-level lapse rates enough to foster peak/preconvective MLCAPE in the 1500-2500 J/kg range. Greatest buoyancy is possible over the coastal plain between the Delmarva peninsula and eastern MA. Wind profiles will be largely unidirectional from the southwest or west-southwest, limiting low-level hodograph size and overall vertical shear. However, strengthening flow aloft with northward extent will support increasing potential for a few supercells northward from the northern Mid-Atlantic into New England, and especially across ME. A counterbalancing effect, however, will be diminishing buoyancy with northward extent over New England. Farther south over much of VA and NC, weak shear will support predominantly multicellular storm modes, with damaging/isolated severe gusts possible in water-loaded downdrafts. ...Northern Plains to central Rockies/High Plains... Scattered to isolated thunderstorms should develop over the central Rockies and higher terrain near the Four Corners and move northeastward to eastward this afternoon -- some of it out onto the central High Plains. Activity should produce locally strong-severe gusts and isolated large hail from downdrafts penetrating deep, well-mixed subcloud layers, though vertical shear this far south of the main flow belt should remain too weak to support well-organized severe potential. Farther north, however, a better-organized severe threat may occur this evening with later-developing convection in the northern Rockies and adjacent High Plains. Increasing large-scale ascent ahead of the Northwest trough will support this activity, along with backed low-level flow and strengthening convergence positioned poleward of the deepening surface low. Early-stage convection may include a few supercells with large hail and damaging gusts, with some convection potentially expanding upscale into one or more clusters as it encounters greater low-level moisture content across central/eastern MT. Large hail will remain possible -- especially with embedded supercell(s), and the severe-gust threat should increase with potential for mesobeta-scale cold-pool development, especially considering the moderately high LCL. A narrow corridor of mid 40s to mid 50s F surface dewpoints, and steep low/middle- level lapse rates, should support MLCAPE in the 1000-1500 J/kg range (locally/briefly higher). Veering winds with height will contribute to effective-shear magnitudes in the 45-55-kt range in support of storm organization. ...Central/southeastern AZ... Cloud debris and mostly light lingering precip are evident over southern AZ, related to the first perturbation, with warming IR cloud tops and overall thinning of clouds noted in recent satellite trends. This should continue and shift northwestward with the initial perturbation through midday into early afternoon, allowing for diurnal heating/destabilization of the boundary layer over southeastern AZ by mid/late afternoon. This, along with favorable low-level moisture, orographic forcing, and weak large-scale ascent preceding the next perturbation aloft, will support widely scattered to scattered afternoon thunderstorms, some of which may produce severe gusts. Valley-floor dewpoints in the 50s F largely should be maintained through the heating/mixing cycle, beneath very steep low-level lapse rates and a well-mixed subcloud layer. A deep southeasterly wind profile in low and middle levels will support northwestward motion of activity, which may aggregate their outflows to encourage both reinforcing development and localized channels of strong-severe wind. The somewhat delayed nature of the destabilization process, and uncertainties about storm coverage/aggregation, preclude greater unconditional probabilities at this time. ..Edwards/Kerr.. 06/30/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 AM CDT Sun Jun 30 2024 Valid 301300Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE I-95/NEAR-COASTAL CORRIDOR FROM THE DELAWARE VALLEY TO SOUTHEASTERN NEW ENGLAND...INCLUDING THE NEW YORK CITY METRO... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK FROM NORTHERN NORTH CAROLINA TO NEW ENGLAND...AND ALSO OVER PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered damaging winds will be possible across parts of the Northeast and Mid-Atlantic States this afternoon/evening. Hail and damaging winds may also occur from eastern Montana into western North Dakota. ...Synopsis... In mid/upper levels, the synoptic pattern over the CONUS will remain dominated by progressive troughs in the Northwest to northern Rockies, and in the Great Lakes to Northeast. An anticyclone aloft, attached to a more extensive, zonal, subtropical ridge, will remain anchored over the southern Plains. What will become the main shortwave perturbation associated with the Northeast trough is apparent over portions of the Upper Great Lakes and MI, and will amplify while moving over southern ON around 00Z. A sharp shortwave trough should result overnight, extending from northern VT across eastern NY to northern WV by 12Z tomorrow. Meanwhile, a series of minor/low-amplitude shortwaves and vorticity lobes will eject northeastward ahead of the Northwest trough, across the central/northern Rockies. A weak, convectively induced perturbation now near the southern AZ border should move slowly northwestward around the subtropical ridging. The northern part of another trough in the mid/upper easterlies is evident in moisture- channel imagery from the MX coastline northwest of Mazatlan, northward to at least southern Chihuahua, moving northwestward. The 11Z surface analysis showed a low over south-central QC, with cold front southwestward over Lake Ontario, southwestern OH, northern/western KY, north-central OK, to east-central NM. By 00Z the cold front should reach parts of ME, southeastern NY, northern VA, central AL, and southern OK, becoming a quasistationary to warm front over the TX Panhandle to northeastern NM. By the end of the period, this boundary should move offshore north of the Outer Banks of NC, and extend over central GA, southern AL/MS, the Red River Valley of TX/OK, and southeastern CO. Separate cyclogenesis should occur today over south-central/southeastern MT, with cold front southwestward across parts of the Great Basin. ...Northern/middle Atlantic Seaboard... Scattered thunderstorms -- mainly in lines but with some discrete activity -- are expected to move mostly eastward across this corridor from late morning through early evening in episodes, with damaging winds likely, a few embedded severe gusts possible, and isolated potential for large hail or a tornado. Low/middle-level destabilization will occur in the preconvective/ prefrontal environment throughout the day, essentially removing already weak MLCINH. This will occur via diurnal heating of the surface and large-scale lift ahead of the approaching Great Lakes trough aloft. Steepening boundary-layer lapse rates amid rich low-level moisture, with dewpoints commonly in the upper 60s to low 70s F, will offset modest mid/upper-level lapse rates enough to foster peak/preconvective MLCAPE in the 1500-2500 J/kg range. Greatest buoyancy is possible over the coastal plain between the Delmarva peninsula and eastern MA. Wind profiles will be largely unidirectional from the southwest or west-southwest, limiting low-level hodograph size and overall vertical shear. However, strengthening flow aloft with northward extent will support increasing potential for a few supercells northward from the northern Mid-Atlantic into New England, and especially across ME. A counterbalancing effect, however, will be diminishing buoyancy with northward extent over New England. Farther south over much of VA and NC, weak shear will support predominantly multicellular storm modes, with damaging/isolated severe gusts possible in water-loaded downdrafts. ...Northern Plains to central Rockies/High Plains... Scattered to isolated thunderstorms should develop over the central Rockies and higher terrain near the Four Corners and move northeastward to eastward this afternoon -- some of it out onto the central High Plains. Activity should produce locally strong-severe gusts and isolated large hail from downdrafts penetrating deep, well-mixed subcloud layers, though vertical shear this far south of the main flow belt should remain too weak to support well-organized severe potential. Farther north, however, a better-organized severe threat may occur this evening with later-developing convection in the northern Rockies and adjacent High Plains. Increasing large-scale ascent ahead of the Northwest trough will support this activity, along with backed low-level flow and strengthening convergence positioned poleward of the deepening surface low. Early-stage convection may include a few supercells with large hail and damaging gusts, with some convection potentially expanding upscale into one or more clusters as it encounters greater low-level moisture content across central/eastern MT. Large hail will remain possible -- especially with embedded supercell(s), and the severe-gust threat should increase with potential for mesobeta-scale cold-pool development, especially considering the moderately high LCL. A narrow corridor of mid 40s to mid 50s F surface dewpoints, and steep low/middle- level lapse rates, should support MLCAPE in the 1000-1500 J/kg range (locally/briefly higher). Veering winds with height will contribute to effective-shear magnitudes in the 45-55-kt range in support of storm organization. ...Central/southeastern AZ... Cloud debris and mostly light lingering precip are evident over southern AZ, related to the first perturbation, with warming IR cloud tops and overall thinning of clouds noted in recent satellite trends. This should continue and shift northwestward with the initial perturbation through midday into early afternoon, allowing for diurnal heating/destabilization of the boundary layer over southeastern AZ by mid/late afternoon. This, along with favorable low-level moisture, orographic forcing, and weak large-scale ascent preceding the next perturbation aloft, will support widely scattered to scattered afternoon thunderstorms, some of which may produce severe gusts. Valley-floor dewpoints in the 50s F largely should be maintained through the heating/mixing cycle, beneath very steep low-level lapse rates and a well-mixed subcloud layer. A deep southeasterly wind profile in low and middle levels will support northwestward motion of activity, which may aggregate their outflows to encourage both reinforcing development and localized channels of strong-severe wind. The somewhat delayed nature of the destabilization process, and uncertainties about storm coverage/aggregation, preclude greater unconditional probabilities at this time. ..Edwards/Kerr.. 06/30/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0359 AM CDT Sun Jun 30 2024 Valid 031200Z - 081200Z ...DISCUSSION... ...Day 4/Wednesday... At least some severe-weather potential will likely exist across parts of the Midwest and south-central Plains within the moist/unstable environment ahead of the advancing cold front and reinforcing outflows. This severe potential could include a corridor from Ohio/Indiana/Illinois southwestward across the Ozarks into Kansas and northern Oklahoma. Deep-layer shear atop the warm sector will likely be weaker as compared to prior days. Additional severe storms may occur near/north of the synoptic front across the north-central High Plains. Risk-magnitude uncertainties still preclude 15+ percent severe-weather probability delineations for these scenarios. ...Day 5/Thursday Midwest including Iowa/Missouri... Guidance is in relatively good agreement that a shortwave trough, and strong jet in its base, will overspread the north-central Great Plains toward the Upper Midwest on Thursday. Ahead of this mid/upper-level trough, very favorable ingredients, including ample instability and rather strong deep-layer shear for the season, may set up across the southern half of Iowa, northern half of Missouri, and possibly nearby parts of southeast Nebraska/northeast Kansas and western Illinois. However, the potential impacts of convection Wednesday night remain a key uncertainty regionally, and will thus defer to future outlooks for an introduction of 15+ percent severe probabilities. ...Days 6-8 Friday-Sunday... Predictability diminishes into this time frame, although corridors of at least some severe storms can be expected daily, generally spanning the northern/central Plains to the Ohio Valley and potentially parts of the East. For instance, on Day 6/Friday, related to the east-northeastward progression of the upper trough, an area of interest includes parts of the Ohio Valley toward the Lake Erie vicinity. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0359 AM CDT Sun Jun 30 2024 Valid 031200Z - 081200Z ...DISCUSSION... ...Day 4/Wednesday... At least some severe-weather potential will likely exist across parts of the Midwest and south-central Plains within the moist/unstable environment ahead of the advancing cold front and reinforcing outflows. This severe potential could include a corridor from Ohio/Indiana/Illinois southwestward across the Ozarks into Kansas and northern Oklahoma. Deep-layer shear atop the warm sector will likely be weaker as compared to prior days. Additional severe storms may occur near/north of the synoptic front across the north-central High Plains. Risk-magnitude uncertainties still preclude 15+ percent severe-weather probability delineations for these scenarios. ...Day 5/Thursday Midwest including Iowa/Missouri... Guidance is in relatively good agreement that a shortwave trough, and strong jet in its base, will overspread the north-central Great Plains toward the Upper Midwest on Thursday. Ahead of this mid/upper-level trough, very favorable ingredients, including ample instability and rather strong deep-layer shear for the season, may set up across the southern half of Iowa, northern half of Missouri, and possibly nearby parts of southeast Nebraska/northeast Kansas and western Illinois. However, the potential impacts of convection Wednesday night remain a key uncertainty regionally, and will thus defer to future outlooks for an introduction of 15+ percent severe probabilities. ...Days 6-8 Friday-Sunday... Predictability diminishes into this time frame, although corridors of at least some severe storms can be expected daily, generally spanning the northern/central Plains to the Ohio Valley and potentially parts of the East. For instance, on Day 6/Friday, related to the east-northeastward progression of the upper trough, an area of interest includes parts of the Ohio Valley toward the Lake Erie vicinity. Read more