Severe Storms

WW 481 SEVERE TSTM CT MA NY VT LO 131640Z - 140000Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 481 NWS Storm Prediction Center Norman OK 1240 PM EDT Thu Jul 13 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Western Connecticut Extreme northwest Massachusetts Central and eastern New York Vermont Lake Ontario * Effective this Thursday afternoon and evening from 1240 PM until 800 PM EDT. * Primary threats include... Scattered damaging wind gusts to 70 mph likely Scattered large hail events to 1.5 inches in diameter possible A tornado or two possible SUMMARY...Severe thunderstorms will increase in coverage along an eastward-moving cold front this afternoon and early evening with a risk for damaging gusts to 70 mph as the primary severe hazard. Large hail will also be possible, and a tornado or two may occur with the strongest storms. The severe thunderstorm watch area is approximately along and 95 statute miles east and west of a line from 40 miles north northwest of Burlington VT to 25 miles east of Binghamton NY. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU1). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 22035. ...Bunting Read more

MD 1526 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF EASTERN ND...WESTERN MN...AND FAR NORTHEASTERN SD
Mesoscale Discussion 1526 NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Jul 13 2023 Areas affected...Portions of eastern ND...western MN...and far northeastern SD Concerning...Severe potential...Watch unlikely Valid 131956Z - 132230Z Probability of Watch Issuance...20 percent SUMMARY...An isolated hail/wind threat may continue for a few more hours this afternoon. But, watch issuance will probably not be needed. DISCUSSION...Thunderstorms have gradually increased in coverage over eastern ND this afternoon along/near a weak surface trough. Persistent west-northwesterly flow aloft strengthens with height at mid/upper levels per recent VWPs from KMVX. Deep-layer shear of 30-40 kt appears sufficient for supercells, but ongoing clustering/updraft interactions lend some uncertainty as to whether thunderstorms will be able to remain at least semi-discrete. Regardless, moderate instability and elongated hodographs aloft should encourage some threat for large hail with any supercell that can persist. Otherwise, isolated severe/damaging winds may occur with any convective downdraft as thunderstorms spread east-southeastward across eastern ND and western MN over the next few hours. At this point, it appears that the overall severe threat will remain isolated enough to preclude watch issuance. ..Gleason/Bunting.. 07/13/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FGF...ABR...BIS... LAT...LON 47229932 47729914 48179753 47349554 46439516 45529740 46149888 46749924 47229932 Read more

MD 1526 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF EASTERN ND...WESTERN MN...AND FAR NORTHEASTERN SD
Mesoscale Discussion 1526 NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Jul 13 2023 Areas affected...Portions of eastern ND...western MN...and far northeastern SD Concerning...Severe potential...Watch unlikely Valid 131956Z - 132230Z Probability of Watch Issuance...20 percent SUMMARY...An isolated hail/wind threat may continue for a few more hours this afternoon. But, watch issuance will probably not be needed. DISCUSSION...Thunderstorms have gradually increased in coverage over eastern ND this afternoon along/near a weak surface trough. Persistent west-northwesterly flow aloft strengthens with height at mid/upper levels per recent VWPs from KMVX. Deep-layer shear of 30-40 kt appears sufficient for supercells, but ongoing clustering/updraft interactions lend some uncertainty as to whether thunderstorms will be able to remain at least semi-discrete. Regardless, moderate instability and elongated hodographs aloft should encourage some threat for large hail with any supercell that can persist. Otherwise, isolated severe/damaging winds may occur with any convective downdraft as thunderstorms spread east-southeastward across eastern ND and western MN over the next few hours. At this point, it appears that the overall severe threat will remain isolated enough to preclude watch issuance. ..Gleason/Bunting.. 07/13/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FGF...ABR...BIS... LAT...LON 47229932 47729914 48179753 47349554 46439516 45529740 46149888 46749924 47229932 Read more

MD 1526 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF EASTERN ND...WESTERN MN...AND FAR NORTHEASTERN SD
Mesoscale Discussion 1526 NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Jul 13 2023 Areas affected...Portions of eastern ND...western MN...and far northeastern SD Concerning...Severe potential...Watch unlikely Valid 131956Z - 132230Z Probability of Watch Issuance...20 percent SUMMARY...An isolated hail/wind threat may continue for a few more hours this afternoon. But, watch issuance will probably not be needed. DISCUSSION...Thunderstorms have gradually increased in coverage over eastern ND this afternoon along/near a weak surface trough. Persistent west-northwesterly flow aloft strengthens with height at mid/upper levels per recent VWPs from KMVX. Deep-layer shear of 30-40 kt appears sufficient for supercells, but ongoing clustering/updraft interactions lend some uncertainty as to whether thunderstorms will be able to remain at least semi-discrete. Regardless, moderate instability and elongated hodographs aloft should encourage some threat for large hail with any supercell that can persist. Otherwise, isolated severe/damaging winds may occur with any convective downdraft as thunderstorms spread east-southeastward across eastern ND and western MN over the next few hours. At this point, it appears that the overall severe threat will remain isolated enough to preclude watch issuance. ..Gleason/Bunting.. 07/13/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FGF...ABR...BIS... LAT...LON 47229932 47729914 48179753 47349554 46439516 45529740 46149888 46749924 47229932 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0253 PM CDT Thu Jul 13 2023 Valid 132000Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF NORTHERN NEW YORK AND WESTERN VERMONT... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE PLAINS...PARTS OF THE OHIO VALLEY...AND NORTHEAST... ...SUMMARY... Numerous severe thunderstorms are likely today across eastern New York and western Vermont, with scattered severe thunderstorms possible across parts of the Ohio Valley and portions of the southern/central Plains. Damaging winds, large hail, and perhaps a couple of tornadoes are possible in these areas. Isolated very large hail may occur across parts of the central Plains. ...Northeast... A line of storms continues to push rapidly east across NY, with strong wind gusts measured recently. Instability remains favorable ahead of the line, and heating continues as well. While the primary threat is for damaging winds, effective SRH over 150 m2/s2 and deep-layer shear over 30 kt will also favor a few supercells with hail or brief/weak tornado risk. For more information see mesoscale discussion 1523. Farther south, a relative minimum in thunderstorm coverage is expected over southern PA into MD, and the Slight Risk has been modified in these areas as the severe risk should remain isolated. The primary risk farther south is expected to remain over the OH Valley, WV and western VA. ...Plains... Extreme moisture and instability is noted into eastern CO where dewpoints are in the 68-72 F range. The backed/easterly low-level flow beneath moderate high level flow is resulting in long hodographs with around 50 kt effective shear. The result should be very large hail, as well as developing damaging wind threat as storms increase in coverage and blend outflows through the OK/TX Panhandles and into western OK. For more information see mesoscale discussion 1519. ..Jewell.. 07/13/2023 .PREV DISCUSSION... /ISSUED 1119 AM CDT Thu Jul 13 2023/ ...NY into New England... Water vapor loop shows a strong mid-level shortwave trough moving across southern Ontario, with a surface cold extending extending from Lake Erie into central/eastern OH. A warm front extends east from a surface low over southeast Ontario Province to the coast near Portland, ME. The cold front will move steadily east this afternoon into NY where thunderstorm development is underway, with an increase in coverage likely over the next few hours. Surface dewpoints in the mid 60s and substantial heating will yield pockets of MLCAPE over 2000 J/kg, along with moderately steep low and mid-level lapse rates. Shear profiles are also rather strong, conducive for organized/supercell structures. Thunderstorms are expected to intensify over eastern NY in the Hudson Valley vicinity before spreading into western New England. A mixture of discrete supercell storms and bowing structures is expected, capable of large hail and damaging wind gusts, and perhaps a tornado or two. Storms should weaken during the evening while moving into a more stable environment with time. See recently issued Mesoscale Discussion 1517 for additional details on short-term thinking in this area. ...KY/WV/OH... As the cold front sags southward into the upper OH Valley by mid-afternoon, scattered thunderstorms are expected to develop. Sufficient westerly flow aloft and MLCAPE of 1500 to locally 2000 J/kg will promote supercells and organized clusters capable of damaging winds and severe hail. ...High Plains from SD to TX... A broad upper-level ridge is present today over the southwest states, with the southern fringe of stronger westerlies extending across CO/KS. A surface dryline will become established by late afternoon extending from the Black Hills vicinity across eastern CO. Forcing will be subtle, however minimal CINH and ample moisture/instability will result in widely scattered intense storms along the dryline, spreading southeastward through the evening. Supercells capable of very large hail appear possible. Storms over western SD/NE, and also over southwest KS and adjacent TX/OK panhandles may persist well into the night and spread eastward across those states. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0253 PM CDT Thu Jul 13 2023 Valid 132000Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF NORTHERN NEW YORK AND WESTERN VERMONT... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE PLAINS...PARTS OF THE OHIO VALLEY...AND NORTHEAST... ...SUMMARY... Numerous severe thunderstorms are likely today across eastern New York and western Vermont, with scattered severe thunderstorms possible across parts of the Ohio Valley and portions of the southern/central Plains. Damaging winds, large hail, and perhaps a couple of tornadoes are possible in these areas. Isolated very large hail may occur across parts of the central Plains. ...Northeast... A line of storms continues to push rapidly east across NY, with strong wind gusts measured recently. Instability remains favorable ahead of the line, and heating continues as well. While the primary threat is for damaging winds, effective SRH over 150 m2/s2 and deep-layer shear over 30 kt will also favor a few supercells with hail or brief/weak tornado risk. For more information see mesoscale discussion 1523. Farther south, a relative minimum in thunderstorm coverage is expected over southern PA into MD, and the Slight Risk has been modified in these areas as the severe risk should remain isolated. The primary risk farther south is expected to remain over the OH Valley, WV and western VA. ...Plains... Extreme moisture and instability is noted into eastern CO where dewpoints are in the 68-72 F range. The backed/easterly low-level flow beneath moderate high level flow is resulting in long hodographs with around 50 kt effective shear. The result should be very large hail, as well as developing damaging wind threat as storms increase in coverage and blend outflows through the OK/TX Panhandles and into western OK. For more information see mesoscale discussion 1519. ..Jewell.. 07/13/2023 .PREV DISCUSSION... /ISSUED 1119 AM CDT Thu Jul 13 2023/ ...NY into New England... Water vapor loop shows a strong mid-level shortwave trough moving across southern Ontario, with a surface cold extending extending from Lake Erie into central/eastern OH. A warm front extends east from a surface low over southeast Ontario Province to the coast near Portland, ME. The cold front will move steadily east this afternoon into NY where thunderstorm development is underway, with an increase in coverage likely over the next few hours. Surface dewpoints in the mid 60s and substantial heating will yield pockets of MLCAPE over 2000 J/kg, along with moderately steep low and mid-level lapse rates. Shear profiles are also rather strong, conducive for organized/supercell structures. Thunderstorms are expected to intensify over eastern NY in the Hudson Valley vicinity before spreading into western New England. A mixture of discrete supercell storms and bowing structures is expected, capable of large hail and damaging wind gusts, and perhaps a tornado or two. Storms should weaken during the evening while moving into a more stable environment with time. See recently issued Mesoscale Discussion 1517 for additional details on short-term thinking in this area. ...KY/WV/OH... As the cold front sags southward into the upper OH Valley by mid-afternoon, scattered thunderstorms are expected to develop. Sufficient westerly flow aloft and MLCAPE of 1500 to locally 2000 J/kg will promote supercells and organized clusters capable of damaging winds and severe hail. ...High Plains from SD to TX... A broad upper-level ridge is present today over the southwest states, with the southern fringe of stronger westerlies extending across CO/KS. A surface dryline will become established by late afternoon extending from the Black Hills vicinity across eastern CO. Forcing will be subtle, however minimal CINH and ample moisture/instability will result in widely scattered intense storms along the dryline, spreading southeastward through the evening. Supercells capable of very large hail appear possible. Storms over western SD/NE, and also over southwest KS and adjacent TX/OK panhandles may persist well into the night and spread eastward across those states. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0253 PM CDT Thu Jul 13 2023 Valid 132000Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF NORTHERN NEW YORK AND WESTERN VERMONT... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE PLAINS...PARTS OF THE OHIO VALLEY...AND NORTHEAST... ...SUMMARY... Numerous severe thunderstorms are likely today across eastern New York and western Vermont, with scattered severe thunderstorms possible across parts of the Ohio Valley and portions of the southern/central Plains. Damaging winds, large hail, and perhaps a couple of tornadoes are possible in these areas. Isolated very large hail may occur across parts of the central Plains. ...Northeast... A line of storms continues to push rapidly east across NY, with strong wind gusts measured recently. Instability remains favorable ahead of the line, and heating continues as well. While the primary threat is for damaging winds, effective SRH over 150 m2/s2 and deep-layer shear over 30 kt will also favor a few supercells with hail or brief/weak tornado risk. For more information see mesoscale discussion 1523. Farther south, a relative minimum in thunderstorm coverage is expected over southern PA into MD, and the Slight Risk has been modified in these areas as the severe risk should remain isolated. The primary risk farther south is expected to remain over the OH Valley, WV and western VA. ...Plains... Extreme moisture and instability is noted into eastern CO where dewpoints are in the 68-72 F range. The backed/easterly low-level flow beneath moderate high level flow is resulting in long hodographs with around 50 kt effective shear. The result should be very large hail, as well as developing damaging wind threat as storms increase in coverage and blend outflows through the OK/TX Panhandles and into western OK. For more information see mesoscale discussion 1519. ..Jewell.. 07/13/2023 .PREV DISCUSSION... /ISSUED 1119 AM CDT Thu Jul 13 2023/ ...NY into New England... Water vapor loop shows a strong mid-level shortwave trough moving across southern Ontario, with a surface cold extending extending from Lake Erie into central/eastern OH. A warm front extends east from a surface low over southeast Ontario Province to the coast near Portland, ME. The cold front will move steadily east this afternoon into NY where thunderstorm development is underway, with an increase in coverage likely over the next few hours. Surface dewpoints in the mid 60s and substantial heating will yield pockets of MLCAPE over 2000 J/kg, along with moderately steep low and mid-level lapse rates. Shear profiles are also rather strong, conducive for organized/supercell structures. Thunderstorms are expected to intensify over eastern NY in the Hudson Valley vicinity before spreading into western New England. A mixture of discrete supercell storms and bowing structures is expected, capable of large hail and damaging wind gusts, and perhaps a tornado or two. Storms should weaken during the evening while moving into a more stable environment with time. See recently issued Mesoscale Discussion 1517 for additional details on short-term thinking in this area. ...KY/WV/OH... As the cold front sags southward into the upper OH Valley by mid-afternoon, scattered thunderstorms are expected to develop. Sufficient westerly flow aloft and MLCAPE of 1500 to locally 2000 J/kg will promote supercells and organized clusters capable of damaging winds and severe hail. ...High Plains from SD to TX... A broad upper-level ridge is present today over the southwest states, with the southern fringe of stronger westerlies extending across CO/KS. A surface dryline will become established by late afternoon extending from the Black Hills vicinity across eastern CO. Forcing will be subtle, however minimal CINH and ample moisture/instability will result in widely scattered intense storms along the dryline, spreading southeastward through the evening. Supercells capable of very large hail appear possible. Storms over western SD/NE, and also over southwest KS and adjacent TX/OK panhandles may persist well into the night and spread eastward across those states. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0215 PM CDT Thu Jul 13 2023 Valid 141200Z - 151200Z ...NO CRITICAL AREAS... No changes. See previous discussion below. ..Bentley.. 07/13/2023 .PREV DISCUSSION... /ISSUED 1216 AM CDT Thu Jul 13 2023/ ...Synopsis... The Southwest mid-level high will shift westward on Friday with very warm temperatures expected across much of the region and generally light winds. This will keep fire weather concerns low, though a few locally enhanced breezes may bring briefly Elevated concerns. Given the localized nature of this threat, no areas were included. The extremely warm temperatures and mostly sunny skies will work to further dry already critically dry fuels across much of the Southwest. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0215 PM CDT Thu Jul 13 2023 Valid 141200Z - 151200Z ...NO CRITICAL AREAS... No changes. See previous discussion below. ..Bentley.. 07/13/2023 .PREV DISCUSSION... /ISSUED 1216 AM CDT Thu Jul 13 2023/ ...Synopsis... The Southwest mid-level high will shift westward on Friday with very warm temperatures expected across much of the region and generally light winds. This will keep fire weather concerns low, though a few locally enhanced breezes may bring briefly Elevated concerns. Given the localized nature of this threat, no areas were included. The extremely warm temperatures and mostly sunny skies will work to further dry already critically dry fuels across much of the Southwest. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Thu Jul 13 2023 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF KANSAS...OKLAHOMA...AND SOUTHWEST MISSOURI... ...SUMMARY... Thunderstorms producing damaging wind and sporadic hail are forecast over much of the central Plains on Friday. Isolated damaging gusts or marginal hail will also be possible over parts of the Mid Atlantic and southern New England, and into parts of the southern High Plains. ...Synopsis... A large upper low will remain over Canada, with an upper ridge over the Southwest. In between, moderate northwest flow aloft will persist over the Plains. To the east, various weaker embedded waves will affect parts of the OH Valley, Mid Atlantic, and Great Lakes. Moisture will remain plentiful east of the Rockies, with the only exception the northern Plains and upper MS Valley where drier air will spread in from the northwest. ...Much of the central Plains... Storms are forecast to be ongoing over NE Friday morning near a stationary front and where low-level theta-e will be substantial. Some of these storms could have hail relatively early in the day, with an increasing threat throughout the day as the storms and the boundary push south into KS where heating will occur. Large hail is most likely with the initial activity, with a strong model signal of an MCS eventually pushing south/southeast into OK and southwest MO late. Damaging winds, as well as heavy rain, will become the primary concern. ..NC into southern New England... A deep-layer moist plume will remain in place with 850 mb winds out of the south/southwest, and a weak surface trough from the Carolinas into southern New England. Little heating will be needed to uncap the air mass, with storms focused over NC and VA during the day where lapse rates will be steepest. Another area of focus will be over southern New England where southerly winds will bring 70s F dewpoints northward across MA. Shear will not be very strong but veering winds with height may favor a few cells producing marginal hail. ...Upper Great Lakes/MI area... Moistening will occur over Lower MI during the day as with a west/southwest low-level wind regime, beneath cool midlevel temperatures and 500 mb winds over 40 kt. Strong heating will occur, which when combined with the rising dewpoints out of the southwest will yield plentiful instability. Scattered storms are expected to form over interior Lower MI during the late afternoon by virtue of weak convergence and an uncapped air mass, and lengthy straight hodographs will favor cellular storm mode with hail possible. ..Jewell.. 07/13/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Thu Jul 13 2023 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF KANSAS...OKLAHOMA...AND SOUTHWEST MISSOURI... ...SUMMARY... Thunderstorms producing damaging wind and sporadic hail are forecast over much of the central Plains on Friday. Isolated damaging gusts or marginal hail will also be possible over parts of the Mid Atlantic and southern New England, and into parts of the southern High Plains. ...Synopsis... A large upper low will remain over Canada, with an upper ridge over the Southwest. In between, moderate northwest flow aloft will persist over the Plains. To the east, various weaker embedded waves will affect parts of the OH Valley, Mid Atlantic, and Great Lakes. Moisture will remain plentiful east of the Rockies, with the only exception the northern Plains and upper MS Valley where drier air will spread in from the northwest. ...Much of the central Plains... Storms are forecast to be ongoing over NE Friday morning near a stationary front and where low-level theta-e will be substantial. Some of these storms could have hail relatively early in the day, with an increasing threat throughout the day as the storms and the boundary push south into KS where heating will occur. Large hail is most likely with the initial activity, with a strong model signal of an MCS eventually pushing south/southeast into OK and southwest MO late. Damaging winds, as well as heavy rain, will become the primary concern. ..NC into southern New England... A deep-layer moist plume will remain in place with 850 mb winds out of the south/southwest, and a weak surface trough from the Carolinas into southern New England. Little heating will be needed to uncap the air mass, with storms focused over NC and VA during the day where lapse rates will be steepest. Another area of focus will be over southern New England where southerly winds will bring 70s F dewpoints northward across MA. Shear will not be very strong but veering winds with height may favor a few cells producing marginal hail. ...Upper Great Lakes/MI area... Moistening will occur over Lower MI during the day as with a west/southwest low-level wind regime, beneath cool midlevel temperatures and 500 mb winds over 40 kt. Strong heating will occur, which when combined with the rising dewpoints out of the southwest will yield plentiful instability. Scattered storms are expected to form over interior Lower MI during the late afternoon by virtue of weak convergence and an uncapped air mass, and lengthy straight hodographs will favor cellular storm mode with hail possible. ..Jewell.. 07/13/2023 Read more

MD 1507 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF NORTHERN/EASTERN MO INTO A SMALL PART OF WESTERN IL
Mesoscale Discussion 1507 NWS Storm Prediction Center Norman OK 0459 PM CDT Wed Jul 12 2023 Areas affected...Parts of northern/eastern MO into a small part of western IL Concerning...Severe potential...Watch unlikely Valid 122159Z - 122330Z Probability of Watch Issuance...20 percent SUMMARY...Storms may intensify into early evening as they move southeastward, with a threat of isolated hail and damaging gusts. DISCUSSION...Thunderstorms have recently developed in northern MO. Based on satellite and mesoanalysis data, this activity is clearly elevated, and likely will remain so in the short term, given substantial MLCINH across the region. However, even for elevated convection that is likely based around 800 mb, MUCAPE in excess of 1500 J/kg and sufficient deep-layer shear (supported by rather strong midlevel west-northwesterlies) conditionally favor the potential for a few organized storms. If any stronger cells/clusters can mature and be sustained into the early evening, some severe threat may evolve with this activity. Steep midlevel lapse rates will favor some hail potential, while a relatively warm and well-mixed boundary layer could support isolated damaging gusts, despite the relatively strong MLCINH. Uncertainty remains rather high regarding the evolution of this convection into the early evening, given its elevated nature and relative lack of stronger large-scale ascent across the area. Watch issuance is currently considered unlikely, but will become possible if organized storms develop or appear imminent. ..Dean/Guyer.. 07/12/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LSX...EAX... LAT...LON 38009052 39109345 39569350 39899337 39789219 39569145 39249070 39049034 38648961 38388969 38109003 38009052 Read more

WW 0477 Status Updates
STATUS FOR WATCH 0477 HAS NOT BEEN ISSUED YET Read more

WW 477 TORNADO IL IN LM 122050Z - 130300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 477 NWS Storm Prediction Center Norman OK 350 PM CDT Wed Jul 12 2023 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Northern Illinois Extreme northwest Indiana Lake Michigan * Effective this Wednesday afternoon and evening from 350 PM until 1000 PM CDT. * Primary threats include... A few tornadoes and a couple intense tornadoes possible Scattered damaging wind gusts to 70 mph possible Isolated very large hail events to 2 inches in diameter possible SUMMARY...Isolated supercell severe thunderstorms are expected to develop and move east-southeast with a risk for a few tornadoes, large hail and damaging thunderstorm wind gusts. The potential also exists for a strong tornado or two to occur. The tornado watch area is approximately along and 45 statute miles north and south of a line from 35 miles southwest of Rockford IL to 10 miles north northeast of Valparaiso IN. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU7). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. && AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 450. Mean storm motion vector 28030. ...Bunting Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Wed Jul 12 2023 Valid 122000Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHERN ILLINOIS/FAR NORTHWESTERN INDIANA...AND PARTS OF EASTERN KANSAS INTO MISSOURI... ...SUMMARY... Severe thunderstorms remain possible across much of Missouri, Illinois, and adjacent portions of the central Plains and Midwest this afternoon through tonight. A few tornadoes should occur this afternoon and evening across parts of northern Illinois into far northwestern Indiana, with a strong tornado possible. Otherwise, damaging winds and large hail should occur with intense thunderstorms that develop, with some potential for significant (75+ mph) severe winds and very large hail across parts of Missouri and Kansas. ...20Z Update... Primary change with this update was to introduce higher tornado probabilities in a narrow corridor across northern IL and far northwestern IN, including Chicago. Recent VWPs from KLOT show impressive low-level shear (0-1 km 35-40+ kt) and enlarged/curved low-level hodographs associated with a focused low-level jet. In the wake of a remnant MCS and lessening precipitation shield, it appears increasingly likely based on recent visible satellite imagery and surface observations that sufficient destabilization to support surface-based convection will occur across this region over the next few hours. Given the very favorable low-level and deep-layer shear available, concern has increased that any supercell which forms in this environment will be capable of producing a tornado. Some potential will exist for a strong tornado as effective SRH strengthens to around 250-350 m2/s2 along/near the developing warm front. The Slight Risk has also been expanded northward in southern Lower MI to account for a small bowing cluster which may develop. No changes have been made to the Enhanced Risk across parts of eastern KS into MO. 18Z sounding from TOP showed warm low/mid-level temperatures and a cap which should continue to inhibit robust convection for at least a couple more hours. Still, intense thunderstorm development is expected later this evening in tandem with a modestly strengthening low-level jet. ..Gleason.. 07/12/2023 .PREV DISCUSSION... /ISSUED 1140 AM CDT Wed Jul 12 2023/ ...Northern IL/southern WI east to northwest OH/southern lower MI... Current MCS continues a general weakening trend based on IR cloud tops, radar trends and recent reports. Air mass recovery in the wake of the morning convection currently appears plausible, aided by a modestly enhanced low-level jet later this afternoon and evening. Steepening mid-level lapse rates will contribute to moderate/pockets of strong MLCAPE this afternoon, and coupled with 40-50 kts of deep-layer shear would result in a favorable parameter space for supercell development by late afternoon/early evening with all severe hazards possible. Will introduce a small 5 percent tornado probability area across this region, where forecast sounding hodograph structure appears most favorable for low-level rotation/tornado potential east of a weak surface low. ...KS/MO/OK this evening... Redevelopment of severe storms appears probable late this afternoon/early evening in the vicinity of an outflow boundary that continues to slow its southward motion across northern portions of KS/MO. Strong/locally extreme MLCAPE is anticipated near/south of this boundary with substantial shear in the cloud-bearing layer. Storms that develop will likely initially possess supercell characteristics with severe hail (possibly significant) and wind, with eventual upscale growth into one or two MCSs capable of potentially significant severe gusts. The Enhanced Risk area has been reoriented based on expected outflow boundary location later this afternoon and a consensus of 12z CAM guidance/HREF ensemble max probabilities. ...IN/OH into New England... A surface quasistationary front currently extends from northern IN into NY and New England. Substantial heating is underway east of the front, which should allow for destabilization and scattered afternoon thunderstorm development. This area lies along the southern fringe of stronger west/southwesterly flow aloft, with 25-35 knots of deep-layer shear. This may be sufficient for a few strong storms later today capable of gusty/damaging winds. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Wed Jul 12 2023 Valid 122000Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHERN ILLINOIS/FAR NORTHWESTERN INDIANA...AND PARTS OF EASTERN KANSAS INTO MISSOURI... ...SUMMARY... Severe thunderstorms remain possible across much of Missouri, Illinois, and adjacent portions of the central Plains and Midwest this afternoon through tonight. A few tornadoes should occur this afternoon and evening across parts of northern Illinois into far northwestern Indiana, with a strong tornado possible. Otherwise, damaging winds and large hail should occur with intense thunderstorms that develop, with some potential for significant (75+ mph) severe winds and very large hail across parts of Missouri and Kansas. ...20Z Update... Primary change with this update was to introduce higher tornado probabilities in a narrow corridor across northern IL and far northwestern IN, including Chicago. Recent VWPs from KLOT show impressive low-level shear (0-1 km 35-40+ kt) and enlarged/curved low-level hodographs associated with a focused low-level jet. In the wake of a remnant MCS and lessening precipitation shield, it appears increasingly likely based on recent visible satellite imagery and surface observations that sufficient destabilization to support surface-based convection will occur across this region over the next few hours. Given the very favorable low-level and deep-layer shear available, concern has increased that any supercell which forms in this environment will be capable of producing a tornado. Some potential will exist for a strong tornado as effective SRH strengthens to around 250-350 m2/s2 along/near the developing warm front. The Slight Risk has also been expanded northward in southern Lower MI to account for a small bowing cluster which may develop. No changes have been made to the Enhanced Risk across parts of eastern KS into MO. 18Z sounding from TOP showed warm low/mid-level temperatures and a cap which should continue to inhibit robust convection for at least a couple more hours. Still, intense thunderstorm development is expected later this evening in tandem with a modestly strengthening low-level jet. ..Gleason.. 07/12/2023 .PREV DISCUSSION... /ISSUED 1140 AM CDT Wed Jul 12 2023/ ...Northern IL/southern WI east to northwest OH/southern lower MI... Current MCS continues a general weakening trend based on IR cloud tops, radar trends and recent reports. Air mass recovery in the wake of the morning convection currently appears plausible, aided by a modestly enhanced low-level jet later this afternoon and evening. Steepening mid-level lapse rates will contribute to moderate/pockets of strong MLCAPE this afternoon, and coupled with 40-50 kts of deep-layer shear would result in a favorable parameter space for supercell development by late afternoon/early evening with all severe hazards possible. Will introduce a small 5 percent tornado probability area across this region, where forecast sounding hodograph structure appears most favorable for low-level rotation/tornado potential east of a weak surface low. ...KS/MO/OK this evening... Redevelopment of severe storms appears probable late this afternoon/early evening in the vicinity of an outflow boundary that continues to slow its southward motion across northern portions of KS/MO. Strong/locally extreme MLCAPE is anticipated near/south of this boundary with substantial shear in the cloud-bearing layer. Storms that develop will likely initially possess supercell characteristics with severe hail (possibly significant) and wind, with eventual upscale growth into one or two MCSs capable of potentially significant severe gusts. The Enhanced Risk area has been reoriented based on expected outflow boundary location later this afternoon and a consensus of 12z CAM guidance/HREF ensemble max probabilities. ...IN/OH into New England... A surface quasistationary front currently extends from northern IN into NY and New England. Substantial heating is underway east of the front, which should allow for destabilization and scattered afternoon thunderstorm development. This area lies along the southern fringe of stronger west/southwesterly flow aloft, with 25-35 knots of deep-layer shear. This may be sufficient for a few strong storms later today capable of gusty/damaging winds. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0125 PM CDT Wed Jul 12 2023 Valid 131200Z - 141200Z Minor refinements were made to the elevated area across parts of northwest Arizona into far southeast Nevada, based on the latest guidance. Otherwise, the previous forecast remains on track. See the discussion below for more details. ..Karstens.. 07/12/2023 .PREV DISCUSSION... /ISSUED 0156 AM CDT Wed Jul 12 2023/ ...Synopsis... The Southwest mid-level high will increase amplitude and re-center itself on Thursday across Arizona with much warmer temperatures and gradual drying of the mid-level moisture plume. Winds will generally be below Elevated or Critical thresholds with a few localized breezes and Elevated areas possible. HREF ensemble guidance does include a better chance for more widespread sustained Elevated fire weather conditions across the Arizona/Utah border. Within this region, afternoon relative humidity reductions to 10-15 percent and sustained winds around 15 mph will be possible. An Elevated delineation was added with this outlook to cover this risk. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0125 PM CDT Wed Jul 12 2023 Valid 131200Z - 141200Z Minor refinements were made to the elevated area across parts of northwest Arizona into far southeast Nevada, based on the latest guidance. Otherwise, the previous forecast remains on track. See the discussion below for more details. ..Karstens.. 07/12/2023 .PREV DISCUSSION... /ISSUED 0156 AM CDT Wed Jul 12 2023/ ...Synopsis... The Southwest mid-level high will increase amplitude and re-center itself on Thursday across Arizona with much warmer temperatures and gradual drying of the mid-level moisture plume. Winds will generally be below Elevated or Critical thresholds with a few localized breezes and Elevated areas possible. HREF ensemble guidance does include a better chance for more widespread sustained Elevated fire weather conditions across the Arizona/Utah border. Within this region, afternoon relative humidity reductions to 10-15 percent and sustained winds around 15 mph will be possible. An Elevated delineation was added with this outlook to cover this risk. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Wed Jul 12 2023 Valid 131200Z - 141200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE OHIO VALLEY INTO THE NORTHEAST...AND PORTIONS OF THE SOUTHERN/CENTRAL PLAINS... ...SUMMARY... Scattered severe thunderstorms capable of producing damaging winds, large hail, and perhaps a tornado or two appear possible Thursday across parts of the Ohio Valley into the Northeast, and portions of the southern/central Plains. Isolated very large hail may occur across parts of the central Plains. ...Ohio Valley into the Northeast... A large, closed upper low will persist over the Hudson Bay vicinity on Thursday. Multiple embedded mid-level perturbations, some convectively augmented, should rotate through the base of the upper trough/low across parts of the OH Valley, Mid-Atlantic, and Northeast through the period. A surface low should track from the Lower Great Lakes into southern Quebec by Thursday afternoon, with a weak trailing cold front extending southwestward from the low across western NY into the OH Valley. Scattered to numerous thunderstorms are expected to develop with daytime heating along/ahead of the front. Moderate buoyancy coupled with sufficient deep-layer shear should foster a mix of supercells and multicell clusters capable of producing both large hail and damaging winds as they spread eastward through Thursday evening. A 25-35 kt south-southwesterly low-level jet should generate enough low-level shear to support some threat for a tornado or two with any supercell that can be sustained. Based on latest guidance trends, have expanded the Slight Risk to include more of the OH Valley into the Mid-Atlantic and Northeast. ...Southern/Central Plains... Within a modest low-level upslope flow regime, robust thunderstorms will likely develop by Thursday afternoon along/east of a surface lee trough/stalled front across parts of the southern/central High Plains. Moderate to strong instability is forecast to develop to the east of this surface boundary from parts of southwestern SD into western/central NE, eastern CO, and western KS. Enhanced mid-level west-northwesterly winds, weaker with southward extent into the southern High Plains, should foster 35-50+ kt of deep-layer shear. Although large-scale ascent should remain weak, multiple supercells should develop across this area and spread generally southeastward through Thursday evening. Steep mid-level lapse rates, strong buoyancy, and long/generally straight hodographs at mid/upper levels will support a threat for large to very large hail with any supercell that develops. Some clustering may eventually occur with a greater threat for severe/damaging winds as a low-level jet modestly strengthens. But, details in convective evolution and possible upscale growth into an MCS Thursday evening/night across the southern/central Plains still remain quite uncertain. ...Northern Plains into the Upper Midwest... Initially high-based convection may develop Thursday afternoon across parts of the northern Plains. With a well-mixed boundary layer and steep low/mid-level lapse rates expected, isolated strong to severe wind gusts should be the main threat with this activity. Additional strong to severe thunderstorms may form and spread southeastward across parts of the Dakotas into the Upper Midwest through the day in a persistent northwesterly flow regime aloft. Deep-layer shear across these regions generally appears strong enough for supercells. However, nebulous forcing lends low confidence in pinpointing where a greater concentration of supercells and/or small bowing clusters capable of producing isolated severe hail/wind gusts may develop Thursday afternoon/evening. Have therefore expanded the Marginal Risk across parts of the northern Plains and Upper Midwest to encompass a wide range of possible convective solutions shown by various guidance. ..Gleason.. 07/12/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Wed Jul 12 2023 Valid 131200Z - 141200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE OHIO VALLEY INTO THE NORTHEAST...AND PORTIONS OF THE SOUTHERN/CENTRAL PLAINS... ...SUMMARY... Scattered severe thunderstorms capable of producing damaging winds, large hail, and perhaps a tornado or two appear possible Thursday across parts of the Ohio Valley into the Northeast, and portions of the southern/central Plains. Isolated very large hail may occur across parts of the central Plains. ...Ohio Valley into the Northeast... A large, closed upper low will persist over the Hudson Bay vicinity on Thursday. Multiple embedded mid-level perturbations, some convectively augmented, should rotate through the base of the upper trough/low across parts of the OH Valley, Mid-Atlantic, and Northeast through the period. A surface low should track from the Lower Great Lakes into southern Quebec by Thursday afternoon, with a weak trailing cold front extending southwestward from the low across western NY into the OH Valley. Scattered to numerous thunderstorms are expected to develop with daytime heating along/ahead of the front. Moderate buoyancy coupled with sufficient deep-layer shear should foster a mix of supercells and multicell clusters capable of producing both large hail and damaging winds as they spread eastward through Thursday evening. A 25-35 kt south-southwesterly low-level jet should generate enough low-level shear to support some threat for a tornado or two with any supercell that can be sustained. Based on latest guidance trends, have expanded the Slight Risk to include more of the OH Valley into the Mid-Atlantic and Northeast. ...Southern/Central Plains... Within a modest low-level upslope flow regime, robust thunderstorms will likely develop by Thursday afternoon along/east of a surface lee trough/stalled front across parts of the southern/central High Plains. Moderate to strong instability is forecast to develop to the east of this surface boundary from parts of southwestern SD into western/central NE, eastern CO, and western KS. Enhanced mid-level west-northwesterly winds, weaker with southward extent into the southern High Plains, should foster 35-50+ kt of deep-layer shear. Although large-scale ascent should remain weak, multiple supercells should develop across this area and spread generally southeastward through Thursday evening. Steep mid-level lapse rates, strong buoyancy, and long/generally straight hodographs at mid/upper levels will support a threat for large to very large hail with any supercell that develops. Some clustering may eventually occur with a greater threat for severe/damaging winds as a low-level jet modestly strengthens. But, details in convective evolution and possible upscale growth into an MCS Thursday evening/night across the southern/central Plains still remain quite uncertain. ...Northern Plains into the Upper Midwest... Initially high-based convection may develop Thursday afternoon across parts of the northern Plains. With a well-mixed boundary layer and steep low/mid-level lapse rates expected, isolated strong to severe wind gusts should be the main threat with this activity. Additional strong to severe thunderstorms may form and spread southeastward across parts of the Dakotas into the Upper Midwest through the day in a persistent northwesterly flow regime aloft. Deep-layer shear across these regions generally appears strong enough for supercells. However, nebulous forcing lends low confidence in pinpointing where a greater concentration of supercells and/or small bowing clusters capable of producing isolated severe hail/wind gusts may develop Thursday afternoon/evening. Have therefore expanded the Marginal Risk across parts of the northern Plains and Upper Midwest to encompass a wide range of possible convective solutions shown by various guidance. ..Gleason.. 07/12/2023 Read more