Severe Storms

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1218 PM CDT Fri Aug 12 2022 Valid 131200Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SOUTHERN INTO EASTERN MONTANA...NORTHWEST NORTH DAKOTA... ...SUMMARY... Isolated severe thunderstorms are possible from southern Montana into northwest North Dakota on late Saturday afternoon through the evening. ...Discussion... A mid-level trough initially over southern British Columbia and WA will move northeast through the southern Canadian Rockies on Saturday. A mid-level anticyclone will remain centered over the central High Plains with a ridge extending northward into the southern Prairie Provinces. A large-scale mid-level trough will encompass much of the East Coast. In the low levels, a weak area of low pressure over the middle MS Valley will aid in focusing isolated to scattered showers/thunderstorms over parts of the southwest Great Lakes. Elevated general thunderstorms are expected with this activity. A residual frontal zone will extend westward into the central Great Plains and arc northward into the northern Great Plains. Weak low-level warm-air advection is forecast in the vicinity of the boundary near the MT/ND/Saskatchewan border. Ample mid- to high-level flow will result in strong deep-layer shear supporting organized storm structures. The overall weak forcing for ascent beneath the mid-level ridge will likely limit storm coverage, but a small storm cluster could yield a hail/wind risk. Farther west, isolated diurnally driven storms are probable over southern MT during the late afternoon. Some of this activity may gradually shift east into east-central MT during the evening. A steep lapse rate environment will conditionally yield a risk for severe gusts with the stronger cores. ..Smith.. 08/12/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1140 AM CDT Fri Aug 12 2022 Valid 121700Z - 131200Z The previous forecast remains valid with no substantial changes. See below for more information. ..Lyons.. 08/12/2022 .PREV DISCUSSION... /ISSUED 0147 AM CDT Fri Aug 12 2022/ ...Synopsis... An upper ridge will persevere across the central U.S. while a mid-level trough meanders along the Pacific Northwest coastline today. Modest mid-level winds overspreading the Cascades will support leeside downslope flow and accompanying Elevated dry/windy surface conditions into the Harney Basin and surrounding areas during the afternoon. Deep-layer ascent will aid in the lifting of a monsoonal airmass across the northern Rockies by afternoon peak heating, with scattered thunderstorms expected. Several of the thunderstorms are expected to be wet, and traversing fuel beds that are highly receptive to fire spread on a spotty basis, precluding isolated dry thunderstorm highlights. Nonetheless, a localized threat for fire starts exists given the number of total lightning strikes that may occur away from precipitation cores, along with the potential for gusty, erratic winds. Despite the presence of upper ridging, surface low development is likely in the northern Plains. Deterministic guidance substantially disagrees regarding how low RH will drop by afternoon peak heating along the Nebraska/South Dakota border. However, there is some signal for at least locally Elevated surface conditions across parts of the northern Plains, perhaps extending east to the Iowa/Minnesota border. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1129 AM CDT Fri Aug 12 2022 Valid 121630Z - 131200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THROUGH LATE EVENING ACROSS PARTS OF THE NORTHERN ROCKIES... ...SUMMARY... Isolated severe gusts and large hail are possible over parts of the northern Rockies and vicinity. ...Northern Rockies through late evening... Embedded speed maxima will move north-northeastward from the Great Basin to the northern Rockies (as evidenced by the ongoing isolated storms), between a closed low off the WA/OR coasts, and west of midlevel high over the central CONUS. Steep lapse rates persist over the Great Basin/northern Rockies, around the western periphery of the monsoonal moisture plume with boundary-layer dewpoints in the 55-60 F range. Modified versions of the 12z soundings from BOI/OTX suggest the potential for moderate buoyancy (MLCAPE in excess of 1000 J/kg) with modestly deep inverted-v profiles, while effective bulk shear of 30-40 kt will be sufficient for some supercell structures. Scattered cells/clusters are expected this afternoon over the higher terrain with surface heating, and in the zone of weak ascent associated with the embedded speed maxima. Isolated damaging winds and large hail will be the main threats with these storms across northern ID and vicinity this afternoon, while high-based convection with strong outflow potential will spread east into western MT this evening. ...Southeast states this afternoon... A midlevel shortwave trough is digging southeastward over the southern Appalachians, as an associated surface cold front likewise progresses southward across the Carolinas/GA/AL. Convection has been ongoing this morning from eastern NC to central SC, and the associated clouds/rain will inhibit additional surface heating across coastal NC. Some cloud breaks from SC across GA/AL will allow destabilization through the afternoon, but poor lapse rates will tend to limit buoyancy and the potential for intense downdrafts. ..Thompson/Bentley.. 08/12/2022 Read more

No watches are valid as of Thu Aug 11 17:52:01 UTC 2022.

No Mesoscale Discussions are in effect as of Thu Aug 11 17:52:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1223 PM CDT Thu Aug 11 2022 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR NORTHERN IDAHO AND WESTERN MONTANA... ...SUMMARY... Isolated thunderstorms capable of a few localized severe gusts are possible on Friday over parts of the northern Rockies. ...Synopsis... A seasonably deep mid/upper-level trough is forecast to persist over the eastern CONUS on Friday, while an upper ridge remains anchored over the central Rockies and Great Plains. An upper-level cyclone off of the Pacific Northwest coast is forecast to move slowly northward and approach Vancouver Island by late Friday night. At the surface, a cold front will push southward across the Carolinas and Southeast. A secondary front will move through portions of the OH/TN Valleys, though the northern portion of this boundary may push northward as a warm front across parts of the Dakotas and Minnesota. ...Northern Rockies... Relatively steep midlevel lapse rates, diurnal heating, and sufficient low-level moisture will support weak to moderate buoyancy by Friday afternoon from parts of northern ID into western MT. The primary limiting factor will be large-scale forcing for ascent remaining displaced to the west of the region near the Pacific coast. Nonetheless, orographic lift and heating will probably result in isolated storms developing during the afternoon. Ample deep-layer shear (40 kt effective) coupled with steep lapse rates will enhance storm organization and the risk for isolated severe gusts during the late afternoon through th evening. ...GA/SC... Scattered to numerous thunderstorms are expected on Friday near the front across portions of GA into SC, and perhaps coastal areas of NC. Modest northwesterly midlevel flow may support sufficient deep-layer shear for some weakly organized storms, though weak midlevel lapse rates and low-level flow are generally expected to limit organized severe-wind potential. Isolated strong gusts capable of tree damage will be possible, especially where stronger diurnal heating/destabilization occurs prior to storm arrival. ..Smith.. 08/11/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1105 AM CDT Thu Aug 11 2022 Valid 111630Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING OVER PARTS OF EASTERN WASHINGTON/OREGON...AND WESTERN IDAHO.... ...SUMMARY... Isolated severe thunderstorms are possible over parts of the inland Pacific Northwest. ...WA/OR/ID... Full sunshine and dewpoints in the 50s to lower 60s are present today over much of the Pacific Northwest region, where afternoon MLCAPE values will range from 500-1500 J/kg. The persistent upper low off the coast will continue to track northward today, with moderately strong southerly deep-layer flow across the region. This will lead to a conditionally favorable environment for severe/supercell thunderstorms. Most CAM solutions suggest at least isolated cells forming this afternoon and early evening over eastern WA/OR and western ID. Any persistent storm in this area will pose a risk of damaging wind gusts and hail. The threat should begin to diminish after 03z. ..Hart.. 08/11/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1029 AM CDT Thu Aug 11 2022 Valid 111700Z - 121200Z Morning surface observations show dry air in place across parts of northeast CA and southern OR as well as across the central High Plains. This will support areas of elevated fire weather conditions this afternoon as winds increase to near 15 mph in the lee of the Cascades and in the vicinity of a surface trough over parts of NE/SD. Confidence in such winds has increased based on recent observations and morning ensemble guidance, warranting an introduction of risk areas. Fuels across both regions are receptive to fire spread based on latest ERC estimates and will support at least regional fire weather concerns. Isolated to scattered thunderstorms remain likely across the northern Rockies, but morning soundings suggest sufficient moisture is in place to favor thunderstorms with wetting precipitation. ..Moore.. 08/11/2022 .PREV DISCUSSION... /ISSUED 0153 AM CDT Thu Aug 11 2022/ ...Synopsis... Fire weather concerns are forecast to be relatively low today as the mid-level ridge shifts east and strengthens over the Rockies. To the west, an upper low is forecast to weaken as it moves slowly along the WA/OR Coast. Lingering mid-level flow and moisture will support locally elevated fire weather concerns, along with the potential for isolated thunderstorms. ...Northwest... Mid-level flow east of the upper low, will support occasional gusty surface winds in the lee of the Sierra and Cascades this afternoon. Coincident with warm temperatures and dry surface conditions, a few hours of locally elevated fire weather concerns are expected within dry fuels. The highest confidence in sustained elevated conditions is expected across southern OR where RH values may fall as low as 15-20%. Farther north, mid-level moisture remains in place near the upper low increasing surface RH values and casting greater uncertainty on the localized fire weather risk. However, a few hours of gusty winds near 15 mph and lower RH may support some risk for locally elevated fire weather in the lee of the Cascades where downslope winds are expected. Additionally, isolated thunderstorms may pose a risk for lightning in dry fuels across portions of eastern WA and ID as moisture is slowly shifted to the east. Please see the latest convective outlook for information on the severe-weather risk. ...Northern High Plains... Weak low-level winds are expected beneath anemic flow aloft as the mid-level ridge strengthens across much of the central US. While not expected to exceed more than 15 or 20 mph, a few gusts enhanced by a lee cyclone across the western Dakotas will develop within a dry and warm airmass with temperatures near 100F. With afternoon RH values of 20-25% and only marginally conducive winds forecast, the fire weather threat is expected to remain localized. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Wed Aug 10 17:48:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1221 PM CDT Wed Aug 10 2022 Valid 111200Z - 121200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated strong storms may occur across the northern Rockies, but the overall severe threat will be relatively low. ...Synopsis... A midlevel high will persist over the central Rockies/High Plains, with an upstream trough over the Pacific Northwest, and a downstream trough over the OH Valley/Northeast. An initial/weak cold front from the southern Plains to the Mid-Atlantic today will drift southward into the northern Gulf states and Southeast, while a reinforcing cold front moves southward into the OH Valley/Northeast. The richest low-level moisture and larger buoyancy will be confined along and south of the initial cold front, where vertical shear will be weak. Isolated downbursts cannot be ruled out across the Carolinas, but poor lapse rates will limit the threat. The reinforcing cold front will become quasi-stationary from SD into IA, and may provide a focus for thunderstorm development Thursday afternoon. However, midlevel lapse rates will be poor across IA during the afternoon, where a narrow corridor of residual boundary-layer dewpoints in the low-mid 60s will contribute to weak buoyancy. Where midlevel lapse rates will be steeper over SD, the boundary layer will likely remain capped. There will be enough deep-layer northwesterly shear for organized/persistent storms along the front in IA, but the weak buoyancy will limit any severe threat. Otherwise, elevated storms are expected overnight from MN into IA as warm advection strengthens, but weak buoyancy will continue to limit storm intensity. Farther west, the monsoonal moisture plume will persist across AZ/NM/UT into western CO/western WY, with scattered (mainly diurnal) storms expected. Some gusty outflow winds will be possible in areas of steeper low-level lapse rates, but substantial clustering of strong-severe storms appears unlikely. ...Northern Rockies Thursday afternoon/evening... After an embedded shortwave trough rotates northward over the OR/WA today, south-southwesterly flow aloft will persist through tomorrow from WA/OR into northern ID. The northwest edge of a monsoonal moisture plume will coincide with a weak baroclinic zone near the WA/OR/ID borders, with the potential for MLCAPE near or above 1000 J/kg and some enhancement to deep-layer flow/shear. Nebulous forcing for ascent (aside from local terrain) suggests that storm coverage will be too isolated and the threat for wind/hail will be too conditional to add severe probabilities at this time. ..Thompson.. 08/10/2022 Read more

MD 1670 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF EASTERN VA AND MD
Mesoscale Discussion 1670 NWS Storm Prediction Center Norman OK 1201 PM CDT Wed Aug 10 2022 Areas affected...Parts of eastern VA and MD Concerning...Severe potential...Watch unlikely Valid 101701Z - 102030Z Probability of Watch Issuance...20 percent SUMMARY...Scattered thunderstorms will spread eastward across the Mid-Atlantic region through the afternoon. Strong to marginally severe gusts will be possible with the stronger storms. A watch is not expected. DISCUSSION...Isolated convective development is underway along the higher terrain in western VA this afternoon, primarily driven by diurnal heating/mixing of a moist boundary layer amid minimal convective inhibition. Ahead of this activity, visible satellite imagery shows mostly clear skies and efficient diurnal heating along and south of a quasi-stationary surface front draped from southern NJ westward along the MD/PA border. While midlevel lapse rates are poor across the warm sector, lower/middle 90s surface temperatures amid lower/middle 70s dewpoints are contributing to a strongly unstable airmass. Generally weak deep-layer flow/shear will limit overall convective organization as it spreads eastward through the afternoon, though 15-20 kt west-southwesterly flow in the 2-4-km layer and deep tropospheric moisture (1.9-2.0 PW per GOES-16 derived PW) should support water-loaded downdrafts with strong to marginally severe gusts of 40-60 mph in the strongest cores. This will especially be the case where any localized clustering of storms occur. Given the weak large-scale ascent and limited vertical wind shear/anticipated convective organization, a watch is not expected. ..Weinman/Hart.. 08/10/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PHI...AKQ...LWX...RNK... LAT...LON 37027626 36987766 37227829 37617894 38657878 39157858 39507817 39597746 39497643 39307608 38907587 37977573 37657575 37327596 37027626 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1118 AM CDT Wed Aug 10 2022 Valid 101630Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE MID-ATLANTIC REGION AND INLAND PACIFIC NORTHWEST.... ...SUMMARY... Isolated severe thunderstorms are possible in parts of the Mid-Atlantic region and inland Pacific Northwest. ...Mid Atlantic... Warm and humid surface conditions are present today over the Mid Atlantic region, with strong daytime heating resulting in afternoon MLCAPE of 2500 J/kg. A consensus of 12z model guidance suggests that scattered thunderstorms will form by early-afternoon over the mountains of eastern WV and western VA. This activity will spread slowly eastward into the Chesapeake Bay region. Forecast soundings and recent ACARS data from the DC/Baltimore area show very weak winds aloft and poor mid-level lapse rates. Given the lack of large scale forcing mechanisms, convection that forms in this area should be weakly organized. Nevertheless, isolated tree damage may briefly occur with the strongest cells. ...WA/OR... An upper low is tracking northward off the OR/WA coast today, with relatively strong southerly deep-layer flow across the interior Pacific Northwest. Mostly clear skies and dewpoints in the 50s will result in a corridor of sufficient CAPE to pose a conditional threat of strong/severe storms this afternoon and evening across the MRGL risk area. Model guidance suggests that the coverage of storms will be quite limited. Nevertheless, any storm that can form/persist will pose a risk of gusty winds and hail. ..Hart/Weinman.. 08/10/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1057 AM CDT Wed Aug 10 2022 Valid 101700Z - 111200Z The forecast generally remains on track. The main adjustments for this update were to trim both the Elevated and Dry Thunderstorm risk areas across the Pacific Northwest to account for recent wetting rainfall and to minimize overlap with areas expected to receive heavy precipitation this afternoon (based on latest ensemble QPF probabilities). Despite the unseasonably high low-level moisture noted in morning surface obs across eastern WA/OR and western ID, forecast soundings continue to show fast storm motions and sufficient diurnal warming to support deeply mixed boundary layers favorable for a few dry lightning strikes over receptive fuels. A few nocturnal showers/thunderstorms are possible over northern MT, but the potential for dry lightning appears too limited for additional highlights. See the previous discussion for additional details. ..Moore.. 08/10/2022 .PREV DISCUSSION... /ISSUED 0155 AM CDT Wed Aug 10 2022/ ...Synopsis... On the western periphery of strong mid-level high pressure dominating the central CONUS, a compact upper low is expected to continue northward along the West Coast. A second trough is forecast move eastward along the northern rim of the ridge across portions of the northern Rockies and High Plains. Enhanced by southerly gradient winds between the upper low and ridge, mid-level moisture will continue to spill into the Pacific Northwest and northern Rockies. Stronger flow aloft and lift from the two troughs will support scattered thunderstorms and the potential for elevated fire weather concerns. ...Northern CA/southern OR and western MT... As heights lower ahead of the upper low and shortwave trough, enhanced mid-level flow is forecast to develop along the northwestern periphery of the ridge across CA/OR and portions of MT. This enhanced flow will overspread a dry and warm airmass in the lee of the northern Sierra and across the northern Rockies/High Plains. Afternoon RH values below 25% and surface winds peaking near 20 mph should support several hours of elevated to near-critical fire weather conditions within receptive fuels. A few high-based thunderstorms may also support strong and erratic gusts this afternoon/evening. ...Dry Thunderstorms... As the upper low continues to move slowly north along the West Coast, dynamic lift will overspread abundant mid-level moisture in place across the Northwest and northern Rockies. Area soundings show PWAT values of 1-1.5 inches supporting elevated CAPE of 500-1000 J/kg. Beneath the unstable layers, modest low-level moisture and warm surface temperatures should result in drier sub-cloud layers with inverted-v structures. Higher evaporation potential should favor a drier storm mode with the threat of occasional cloud to ground strikes to receptive fuels. IsoDryT probabilities will be maintained across portions of the interior Northwest and northern Rockies. Farther west across the Olympic Peninsula and western Washington, dry thunder potential is less certain given much cooler surface conditions near an inland marine layer. While elevated buoyancy is expected to support a risk for storms beneath the cold core of the upper low, storm mode is forecast to be significantly wetter. While isolated cloud to ground strikes will be possible within receptive fuels, dry thunderstorms appear unlikely, and IsoDryT probabilities will be held farther east. For additional information of the severe-weather risk, please see the most recent Convective Outlook. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Tue Aug 9 17:53:01 UTC 2022.

MD 1669 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF CENTRAL OR...FAR NORTHEAST CA...AND FAR NORTHWEST NV
Mesoscale Discussion 1669 NWS Storm Prediction Center Norman OK 1251 PM CDT Tue Aug 09 2022 Areas affected...Parts of central OR...far northeast CA...and far northwest NV Concerning...Severe potential...Watch unlikely Valid 091751Z - 092115Z Probability of Watch Issuance...20 percent SUMMARY...The risk of isolated large hail and locally severe gusts will gradually increase through the afternoon. A watch is not currently expected. DISCUSSION...Ahead of a mid/upper-level low off the coast of northern CA, a belt of deep/enhanced meridional flow (sampled by regional 12z soundings) will continue overspreading northern CA into south-central OR this afternoon. Recent water vapor imagery showed a subtle embedded midlevel impulse moving northward across the area, which combined with sufficient midlevel moisture/buoyancy has resulted in an uptick in shallow convection along the higher terrain in OR. Currently, lingering low-level inhibition and minimal buoyancy are limiting updraft intensity, though isolated small hail and locally strong gusts are still possible with this activity. Behind this initial uptick in convection, diurnal heating/mixing beneath a plume of modest midlevel lapse rates should contribute to moderate surface-based instability by this afternoon, though ongoing activity casts uncertainty on overall boundary-layer recovery (especially over parts of OR along the Cascades). Nevertheless, if an additional uptick in diurnally enhanced convection can intercept pockets of surface-based inflow, 40-50 kt effective shear -- characterized by a long/generally straight hodograph -- would support splitting supercell structures and locally organized clusters. Isolated large hail and locally severe gusts may accompany any persistent rotating updrafts or organized clusters, though the threat appears too localized for a watch. ..Weinman/Hart.. 08/09/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BOI...LKN...PDT...REV...MFR...PQR... LAT...LON 42301812 41721828 41131887 40861978 41062044 41962083 42782154 43462208 43872223 44552227 44912216 45112174 45182055 44911942 44431864 43801827 42761806 42301812 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1223 PM CDT Tue Aug 09 2022 Valid 101200Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS WEDNESDAY AFTERNOON AND EVENING ACROSS NORTHERN AND EASTERN VIRGINIA...CENTRAL AND EASTERN MARYLAND...MUCH OF DELAWARE...CENTRAL AND EASTERN WASHINGTON AND NORTHEASTERN OREGON... ...SUMMARY... A cluster of strong thunderstorms, posing a risk for locally gusty and damaging winds, may develop across parts of the Mid Atlantic Wednesday afternoon and evening. Isolated strong thunderstorms may also impact parts of the northern intermountain region, accompanied by at least some risk for severe weather. ...Synopsis... Little change to the amplified regime across the mid- and subtropical latitudes of the eastern Pacific into the interior of the U.S. is forecast through this period. Mid-level ridging, with a broad and prominent embedded high, will remain centered across the Rockies and Great Plains, downstream of large-scale troughing near and offshore of the Pacific coast. Near and just east of the mid-level trough axis, a significant embedded low appears likely to continue migrating slowly northward just offshore of the Oregon and Washington coasts. To the east of the ridging, large-scale mid-level troughing, with a couple of vigorous embedded perturbations, is forecast to gradually dig across and southeast of the southern Hudson/James Bay and upper Great Lakes vicinities. Models suggest that this will be preceded by weak mid-level troughing digging southeast of the lower Great Lakes through the Mid Atlantic vicinity by late Wednesday night. In association with this regime, an initial cold front may gradually stall and weaken across the Mid Atlantic coast and Ohio Valley into Ozark Plateau and central Great Plains vicinity, as a reinforcing cold front advances across much of the Great Lakes region by daybreak Thursday. Seasonably high moisture content will largely remain confined to the south of the lead front, to the east of the Rockies. Across the west, a plume of monsoonal moisture emanating from Southwest will be maintained, but perhaps slowly shift eastward across the northern intermountain region/Great Basin, ahead of subsidence/drying in the wake of the offshore low. ...Mid Atlantic... As the surface front advances offshore of the northern Mid Atlantic coast, models suggest that insolation across and to the lee of the Blue Ridge may contribute to a zone of stronger differential surface heating across the Potomac/Chesapeake vicinity Wednesday afternoon. Despite rather weak deep-layer mean flow and shear, it is possible that this boundary could provide a focus for consolidating thunderstorm activity with some potential to organize by late afternoon. Aided by inflow of seasonably moist boundary-layer air characterized by CAPE on the order of 1000-2000+ J/kg, this convection may generate outflow supportive of strong to severe surface gusts, before weakening Wednesday evening. ...Washington/Oregon... Uncertainty lingers concerning the extent and degree of appreciable boundary-layer destabilization across the northern intermountain region on Wednesday. However, aided by large-scale forcing for ascent to the northeast through east of the northward migrating offshore low, at least widely scattered thunderstorm development appears possible Wednesday afternoon and evening, particularly off the mountains of northeastern Oregon and near the higher terrain north of the Columbia Plateau. Beneath 40-70+ kt southerly flow in the 500-300 mb layer, forecast soundings indicate that hodographs will become conditionally supportive of supercells posing at least a risk for severe wind and hail. ..Kerr.. 08/09/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 1148 AM CDT Tue Aug 09 2022 Valid 091630Z - 101200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE MID-ATLANTIC INTO SOUTHERN NEW ENGLAND...AND IN PARTS OF THE INTERIOR PACIFIC NORTHWEST.... CORRECTED FOR HAIL GRAPHIC ERROR ...SUMMARY... Thunderstorms associated with damaging wind gusts will be possible today from the Mid-Atlantic into southern New England, and in parts of the Interior Pacific Northwest. ...Northeast States... A surface cold front is analyzed this morning from central New England into central PA. This front will sag southeastward today into a hot/moist low-level environment with temperatures in the 90s and dewpoints in the 70s. Forecast soundings show weak mid-level lapse rates and warm temperatures aloft, which should be negative factors for convective coverage and intensity. Nevertheless, at least isolated thunderstorms are expected to form on the front later today, with the strongest cells posing a risk of locally damaging wind gusts. ...Central OR... A large upper low is present off the coast of northern CA today, with rather strong southerly deep-layer flow extending northward across much of western and central OR. 12z model guidance continues to show multiple waves of convection affecting the MRGL risk area through this evening, where sufficient CAPE and deep-layer shear will be present for a few organized storms. The main threat appears to be locally damaging wind gusts in pockets of stronger heating, but an isolated supercell or two cannot be ruled out, with an associated risk of gusty winds or hail. ..Hart/Weinman.. 08/09/2022 Read more

MD 1668 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EASTERN MD...SOUTHERN PA...DE...NJ...SOUTHERN NY..CT...MA...RI
Mesoscale Discussion 1668 NWS Storm Prediction Center Norman OK 1143 AM CDT Tue Aug 09 2022 Areas affected...Eastern MD...Southern PA...DE...NJ...Southern NY..CT...MA...RI Concerning...Severe potential...Watch unlikely Valid 091643Z - 091845Z Probability of Watch Issuance...20 percent SUMMARY...Isolated damaging wind gusts are possible this afternoon from the northern Mid-Atlantic into southern New England. DISCUSSION...Recent surface analysis places a low over southern ME, with a cold front extending southwestward from this low across the central Hudson Valley into central PA. A weak trough also precedes this front. extending southward through central MA and central CT into northern NJ and far eastern PA. Current surface observations also reveal dewpoints in the 70s areawide, with numerous locations reporting dewpoints in mid 70s. Cumulus continues to deepen in the vicinity of the surface trough as the air mass heats and destabilizes. This trend is expected to persist throughout the afternoon, resulting in the development of scattered thunderstorms. The stronger mid-level flow will be over ME, displaced north of the stronger buoyancy, which is expected across the Delmarva, eastern PA, and NJ. Additionally, the overall instability will be limited by weak mid-level lapse rates and warm thermodynamic profiles. Even so, steep low-level lapse rates coupled with a very moist air mass could still support locally damaging wind gusts with any stronger storms. ..Mosier/Hart.. 08/09/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BOX...OKX...ALY...PHI...BGM...CTP...LWX... LAT...LON 38717592 39607707 40517661 42477238 41977151 40807305 39687417 38757492 38717592 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1008 AM CDT Tue Aug 09 2022 Valid 091700Z - 101200Z The previous forecast remains on track with only minor adjustments required. 12 UTC regional soundings and latest satellite estimates show PWAT values have increase to around 1 inch across much of the Pacific Northwest. An embedded impulse is noted in morning water-vapor imagery pivoting north/northeastward along the West Coast. This feature will support scattered thunderstorm development by early afternoon. The highest thunderstorm coverage remains most likely across central to southeast OR, but more isolated dry thunderstorms are possible in this periphery of this axis. Strong thunderstorm outflows remain likely and may reach severe (58+ mph) wind speeds. See the previous discussion for additional details, and see the recent Day 1 Convective Outlook for more information on the severe weather potential. ..Moore.. 08/09/2022 .PREV DISCUSSION... /ISSUED 0145 AM CDT Tue Aug 09 2022/ ...Synopsis... An upper ridge will persist across the western CONUS as a mid-level closed low impinges on the West Coast today. Strong 500 mb flow in advance of the mid-level closed low will overspread the Cascades during the afternoon, providing adequate upper support for initiating several thunderstorms when considering the presence of low to mid-level monsoonal moisture. While storms will be fast moving, the concentration of storms (several of which may be training) along with precipitable water values approaching 1.25 inches suggest that wetting rains should accompany at least most of the storms. Nonetheless, the abundance of storms will also increase the odds of peripheral lightning strikes away from cores. Downward momentum of the stronger mid-level flow in thunderstorms may also support strong, erratic gusts. As such, isolated dry thunderstorm highlights have been maintained for the combined threats of peripheral strikes within spotty dry fuel beds and gusty thunderstorm winds, which can exacerbate ongoing wildfires. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Mon Aug 8 17:58:01 UTC 2022.