SPC MD 1958

1 month ago
MD 1958 CONCERNING SEVERE THUNDERSTORM WATCH 591... FOR PORTIONS OF EASTERN MINNESOTA AND WESTERN WISCONSIN
Mesoscale Discussion 1958 NWS Storm Prediction Center Norman OK 0724 PM CDT Fri Aug 15 2025 Areas affected...portions of eastern Minnesota and western Wisconsin Concerning...Severe Thunderstorm Watch 591... Valid 160024Z - 160200Z The severe weather threat for Severe Thunderstorm Watch 591 continues. SUMMARY...Ongoing storms have begun to cluster this evening. This trend is expected to continue, transitioning the primary threat towards damaging gusts and sporadic hail. DISCUSSION...Across WW 591, scattered strong to severe thunderstorms are ongoing and expected to continue. The initially more cellular storms have gradually coalesced into a more cluster/multicellular mode over the last 2 hours. With that transition, damaging gusts appear to be the primary threat as outflow continues to coalesce along and south of the stalled frontal boundary through eastern MN and western WI. While strong outflow should be the primary risk through the remainder of the evening, moderate deep-layer shear and buoyancy could still support sporadic hail potential with stronger but more transient updrafts. Observational and CAM trends suggest these storm will gradually move east/southeast with some severe risk through this evening. The southern extent and duration of the severe risk is somewhat uncertain as a remnant cold pool from a prior cluster is present near the IA/MN/WI border region. However, the environment should remain broadly favorable for damaging gusts and occasional hail focused on the eastern portions of WW591 for a couple more hours. ..Lyons.. 08/16/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GRB...ARX...MPX... LAT...LON 45209374 45389289 45069100 44609038 44129020 43759050 43799130 43919205 44169294 44449338 44719369 45209374 MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN Read more

SPC Severe Thunderstorm Watch 591 Status Reports

1 month ago
WW 0591 Status Updates
STATUS REPORT ON WW 591 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 ENE MKT TO 40 NNW EAU. ..LYONS..08/16/25 ATTN...WFO...MPX...ARX... STATUS REPORT FOR WS 591 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MNC049-131-157-160240- MN . MINNESOTA COUNTIES INCLUDED ARE GOODHUE RICE WABASHA WIC011-017-019-033-035-053-091-093-109-121-160240- WI . WISCONSIN COUNTIES INCLUDED ARE BUFFALO CHIPPEWA CLARK DUNN EAU CLAIRE JACKSON PEPIN PIERCE ST. CROIX TREMPEALEAU THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

SPC Severe Thunderstorm Watch 591 Status Reports

1 month ago
WW 0591 Status Updates
STATUS REPORT ON WW 591 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 ENE MKT TO 40 NNW EAU. ..LYONS..08/16/25 ATTN...WFO...MPX...ARX... STATUS REPORT FOR WS 591 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MNC049-131-157-160240- MN . MINNESOTA COUNTIES INCLUDED ARE GOODHUE RICE WABASHA WIC011-017-019-033-035-053-091-093-109-121-160240- WI . WISCONSIN COUNTIES INCLUDED ARE BUFFALO CHIPPEWA CLARK DUNN EAU CLAIRE JACKSON PEPIN PIERCE ST. CROIX TREMPEALEAU THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

SPC Severe Thunderstorm Watch 591 Status Reports

1 month ago
WW 0591 Status Updates
STATUS REPORT ON WW 591 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 ENE MKT TO 40 NNW EAU. ..LYONS..08/16/25 ATTN...WFO...MPX...ARX... STATUS REPORT FOR WS 591 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MNC049-131-157-160240- MN . MINNESOTA COUNTIES INCLUDED ARE GOODHUE RICE WABASHA WIC011-017-019-033-035-053-091-093-109-121-160240- WI . WISCONSIN COUNTIES INCLUDED ARE BUFFALO CHIPPEWA CLARK DUNN EAU CLAIRE JACKSON PEPIN PIERCE ST. CROIX TREMPEALEAU THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

SPC Severe Thunderstorm Watch 591 Status Reports

1 month ago
WW 0591 Status Updates
STATUS REPORT ON WW 591 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 ENE MKT TO 40 NNW EAU. ..LYONS..08/16/25 ATTN...WFO...MPX...ARX... STATUS REPORT FOR WS 591 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MNC049-131-157-160240- MN . MINNESOTA COUNTIES INCLUDED ARE GOODHUE RICE WABASHA WIC011-017-019-033-035-053-091-093-109-121-160240- WI . WISCONSIN COUNTIES INCLUDED ARE BUFFALO CHIPPEWA CLARK DUNN EAU CLAIRE JACKSON PEPIN PIERCE ST. CROIX TREMPEALEAU THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

SPC Severe Thunderstorm Watch 591 Status Reports

1 month ago
WW 0591 Status Updates
STATUS REPORT ON WW 591 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 ENE MKT TO 40 NNW EAU. ..LYONS..08/16/25 ATTN...WFO...MPX...ARX... STATUS REPORT FOR WS 591 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MNC049-131-157-160240- MN . MINNESOTA COUNTIES INCLUDED ARE GOODHUE RICE WABASHA WIC011-017-019-033-035-053-091-093-109-121-160240- WI . WISCONSIN COUNTIES INCLUDED ARE BUFFALO CHIPPEWA CLARK DUNN EAU CLAIRE JACKSON PEPIN PIERCE ST. CROIX TREMPEALEAU THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

SPC Severe Thunderstorm Watch 591 Status Reports

1 month ago
WW 0591 Status Updates
STATUS REPORT ON WW 591 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 ENE MKT TO 40 NNW EAU. ..LYONS..08/16/25 ATTN...WFO...MPX...ARX... STATUS REPORT FOR WS 591 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MNC049-131-157-160240- MN . MINNESOTA COUNTIES INCLUDED ARE GOODHUE RICE WABASHA WIC011-017-019-033-035-053-091-093-109-121-160240- WI . WISCONSIN COUNTIES INCLUDED ARE BUFFALO CHIPPEWA CLARK DUNN EAU CLAIRE JACKSON PEPIN PIERCE ST. CROIX TREMPEALEAU THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

SPC Severe Thunderstorm Watch 591

1 month ago
WW 591 SEVERE TSTM MN WI 152225Z - 160400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 591 NWS Storm Prediction Center Norman OK 525 PM CDT Fri Aug 15 2025 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southern Minnesota Western Wisconsin * Effective this Friday afternoon and evening from 525 PM until 1100 PM CDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Scattered large hail events to 1.5 inches in diameter possible SUMMARY...Strong to severe thunderstorms will continue to develop across the region through early evening. Hail will be possible, and at least isolated damaging wind potential will exist, especially as storms merge/organize as they progress east-southeastward. The severe thunderstorm watch area is approximately along and 35 statute miles north and south of a line from 35 miles north of Redwood Falls MN to 55 miles east southeast of Eau Claire WI. 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. && OTHER WATCH INFORMATION...CONTINUE...WW 590... 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 550. Mean storm motion vector 28025. ...Guyer Read more

SPC Severe Thunderstorm Watch 592 Status Reports

1 month ago
WW 0592 Status Updates
STATUS REPORT ON WW 592 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 E BRL TO 30 SSE RFD. ..LYONS..08/16/25 ATTN...WFO...DVN...ILX...LOT... STATUS REPORT FOR WS 592 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC011-095-123-143-155-175-179-203-160240- IL . ILLINOIS COUNTIES INCLUDED ARE BUREAU KNOX MARSHALL PEORIA PUTNAM STARK TAZEWELL WOODFORD THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

SPC Severe Thunderstorm Watch 592 Status Reports

1 month ago
WW 0592 Status Updates
STATUS REPORT ON WW 592 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 E BRL TO 30 SSE RFD. ..LYONS..08/16/25 ATTN...WFO...DVN...ILX...LOT... STATUS REPORT FOR WS 592 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC011-095-123-143-155-175-179-203-160240- IL . ILLINOIS COUNTIES INCLUDED ARE BUREAU KNOX MARSHALL PEORIA PUTNAM STARK TAZEWELL WOODFORD THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

SPC Severe Thunderstorm Watch 592 Status Reports

1 month ago
WW 0592 Status Updates
STATUS REPORT ON WW 592 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 E BRL TO 30 SSE RFD. ..LYONS..08/16/25 ATTN...WFO...DVN...ILX...LOT... STATUS REPORT FOR WS 592 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC011-095-123-143-155-175-179-203-160240- IL . ILLINOIS COUNTIES INCLUDED ARE BUREAU KNOX MARSHALL PEORIA PUTNAM STARK TAZEWELL WOODFORD THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

SPC Severe Thunderstorm Watch 592 Status Reports

1 month ago
WW 0592 Status Updates
STATUS REPORT ON WW 592 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 E BRL TO 30 SSE RFD. ..LYONS..08/16/25 ATTN...WFO...DVN...ILX...LOT... STATUS REPORT FOR WS 592 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC011-095-123-143-155-175-179-203-160240- IL . ILLINOIS COUNTIES INCLUDED ARE BUREAU KNOX MARSHALL PEORIA PUTNAM STARK TAZEWELL WOODFORD THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

SPC Severe Thunderstorm Watch 592 Status Reports

1 month ago
WW 0592 Status Updates
STATUS REPORT ON WW 592 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 E BRL TO 30 SSE RFD. ..LYONS..08/16/25 ATTN...WFO...DVN...ILX...LOT... STATUS REPORT FOR WS 592 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC011-095-123-143-155-175-179-203-160240- IL . ILLINOIS COUNTIES INCLUDED ARE BUREAU KNOX MARSHALL PEORIA PUTNAM STARK TAZEWELL WOODFORD THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

SPC Severe Thunderstorm Watch 592 Status Reports

1 month ago
WW 0592 Status Updates
STATUS REPORT ON WW 592 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 E BRL TO 30 SSE RFD. ..LYONS..08/16/25 ATTN...WFO...DVN...ILX...LOT... STATUS REPORT FOR WS 592 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC011-095-123-143-155-175-179-203-160240- IL . ILLINOIS COUNTIES INCLUDED ARE BUREAU KNOX MARSHALL PEORIA PUTNAM STARK TAZEWELL WOODFORD THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

SPC Severe Thunderstorm Watch 592

1 month ago
WW 592 SEVERE TSTM IL 152345Z - 160400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 592 NWS Storm Prediction Center Norman OK 645 PM CDT Fri Aug 15 2025 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northern Illinois * Effective this Friday evening from 645 PM until 1100 PM CDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1 inch in diameter possible SUMMARY...A well-organized cluster of storms with a history of 70+ mph wind gusts across eastern Iowa will continue southeastward into northern Illinois. Even with a weakening trend over time, damaging winds will remain a possibility, and perhaps some hail. The severe thunderstorm watch area is approximately along and 50 statute miles north and south of a line from 5 miles west northwest of Moline IL to 75 miles east of Moline IL. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU2). 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. && OTHER WATCH INFORMATION...CONTINUE...WW 590...WW 591... AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 30040. ...Guyer Read more

SPC Aug 16, 2025 0100 UTC Day 1 Convective Outlook

1 month ago
SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0759 PM CDT Fri Aug 15 2025 Valid 160100Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO THE OVERNIGHT HOURS ACROSS PARTS OF CENTRAL AND EASTERN SOUTH DAKOTA...NORTHERN NEBRASKA...SOUTHWESTERN MINNESOTA...NORTHWESTERN IOWA...PARTS OF SOUTHEASTERN IOWA AND SOUTHWESTERN WISCONSIN... ...SUMMARY... An organizing cluster of thunderstorms with potential to produce strong to severe wind gusts may still evolve later this evening into the overnight hours across parts of the middle Missouri Valley and adjacent Great Plains. ...01Z Update... Stronger westerlies remain generally confined to the higher latitudes, near/north of the Canadian/U.S. border. To the southwest of one significant embedded short wave trough crossing the Hudson Bay and northern Ontario vicinity, modest westerly mid-level flow (including speeds of 30-40 kt around 500 mb) is overspreading areas as far south as the Dakotas into Upper Midwest, near the northern periphery of mid-level ridging. Forcing associated with subtle perturbations embedded within this regime has contributed to several developing clusters of storms. A couple now propagating east of the upper Mississippi Valley appear to be in the process of weakening, likely due to some combination of weak/weakening lift and increasing inhibition beneath relatively warm mid-level temperatures encompassing much of the northern and central Great Plains into Midwest. Beneath steeper mid-level lapse rates upstream, boundary-layer moisture east of the lee surface trough across the high plains is still contributing to strong to extreme potential instability across much of central and eastern South Dakota/Nebraska, as scattered high based convection emerges from eastern Wyoming and northeastern Colorado. It appears possible that low-level forcing for ascent, near the nose of a nocturnally strengthening southerly low-level jet, could contribute to a consolidating and upscale growing cluster, particularly as activity acquires more unstable inflow later this evening into the overnight. Various model output, including the NAM and Rapid Refresh, suggest that the evolution of a notable convective perturbation is possible, which could be accompanied by a swath of strong to severe wind gusts. ..Kerr.. 08/16/2025 Read more

SPC Aug 16, 2025 0100 UTC Day 1 Convective Outlook

1 month ago
SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0759 PM CDT Fri Aug 15 2025 Valid 160100Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO THE OVERNIGHT HOURS ACROSS PARTS OF CENTRAL AND EASTERN SOUTH DAKOTA...NORTHERN NEBRASKA...SOUTHWESTERN MINNESOTA...NORTHWESTERN IOWA...PARTS OF SOUTHEASTERN IOWA AND SOUTHWESTERN WISCONSIN... ...SUMMARY... An organizing cluster of thunderstorms with potential to produce strong to severe wind gusts may still evolve later this evening into the overnight hours across parts of the middle Missouri Valley and adjacent Great Plains. ...01Z Update... Stronger westerlies remain generally confined to the higher latitudes, near/north of the Canadian/U.S. border. To the southwest of one significant embedded short wave trough crossing the Hudson Bay and northern Ontario vicinity, modest westerly mid-level flow (including speeds of 30-40 kt around 500 mb) is overspreading areas as far south as the Dakotas into Upper Midwest, near the northern periphery of mid-level ridging. Forcing associated with subtle perturbations embedded within this regime has contributed to several developing clusters of storms. A couple now propagating east of the upper Mississippi Valley appear to be in the process of weakening, likely due to some combination of weak/weakening lift and increasing inhibition beneath relatively warm mid-level temperatures encompassing much of the northern and central Great Plains into Midwest. Beneath steeper mid-level lapse rates upstream, boundary-layer moisture east of the lee surface trough across the high plains is still contributing to strong to extreme potential instability across much of central and eastern South Dakota/Nebraska, as scattered high based convection emerges from eastern Wyoming and northeastern Colorado. It appears possible that low-level forcing for ascent, near the nose of a nocturnally strengthening southerly low-level jet, could contribute to a consolidating and upscale growing cluster, particularly as activity acquires more unstable inflow later this evening into the overnight. Various model output, including the NAM and Rapid Refresh, suggest that the evolution of a notable convective perturbation is possible, which could be accompanied by a swath of strong to severe wind gusts. ..Kerr.. 08/16/2025 Read more

SPC Aug 16, 2025 0100 UTC Day 1 Convective Outlook

1 month ago
SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0759 PM CDT Fri Aug 15 2025 Valid 160100Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO THE OVERNIGHT HOURS ACROSS PARTS OF CENTRAL AND EASTERN SOUTH DAKOTA...NORTHERN NEBRASKA...SOUTHWESTERN MINNESOTA...NORTHWESTERN IOWA...PARTS OF SOUTHEASTERN IOWA AND SOUTHWESTERN WISCONSIN... ...SUMMARY... An organizing cluster of thunderstorms with potential to produce strong to severe wind gusts may still evolve later this evening into the overnight hours across parts of the middle Missouri Valley and adjacent Great Plains. ...01Z Update... Stronger westerlies remain generally confined to the higher latitudes, near/north of the Canadian/U.S. border. To the southwest of one significant embedded short wave trough crossing the Hudson Bay and northern Ontario vicinity, modest westerly mid-level flow (including speeds of 30-40 kt around 500 mb) is overspreading areas as far south as the Dakotas into Upper Midwest, near the northern periphery of mid-level ridging. Forcing associated with subtle perturbations embedded within this regime has contributed to several developing clusters of storms. A couple now propagating east of the upper Mississippi Valley appear to be in the process of weakening, likely due to some combination of weak/weakening lift and increasing inhibition beneath relatively warm mid-level temperatures encompassing much of the northern and central Great Plains into Midwest. Beneath steeper mid-level lapse rates upstream, boundary-layer moisture east of the lee surface trough across the high plains is still contributing to strong to extreme potential instability across much of central and eastern South Dakota/Nebraska, as scattered high based convection emerges from eastern Wyoming and northeastern Colorado. It appears possible that low-level forcing for ascent, near the nose of a nocturnally strengthening southerly low-level jet, could contribute to a consolidating and upscale growing cluster, particularly as activity acquires more unstable inflow later this evening into the overnight. Various model output, including the NAM and Rapid Refresh, suggest that the evolution of a notable convective perturbation is possible, which could be accompanied by a swath of strong to severe wind gusts. ..Kerr.. 08/16/2025 Read more
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