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SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Mon Apr 21 2025 Valid 211630Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper OH Valley... Morning surface analysis and satellite imagery show a cold front sweeping eastward across OH. Considerable cloud cover is present ahead of the front, but a narrow corridor of heating immediately ahead of the front will allow a period of heating - promoting scattered thunderstorms. Low-level moisture is limited with dewpoints only in the 50s, and forecast soundings show CAPE values generally below 1000 J/kg. Nevertheless, strong low and mid-level winds and considerable vertical shear will promote a risk of a few organized/severe storms capable of damaging wind gusts and perhaps a tornado or two. Refer to upcoming MCD #511 for further details. ...LA/MS/AL/GA/TN... The aforementioned surface cold front extends southeastward across west TN. A relatively moist air mass is present ahead of the front from southeast LA into parts of MS/AL and middle/east TN, although considerable cloud cover will limit heating. Most 12z models suggest scattered thunderstorms will form in this zone during the late afternoon and evening, with sufficient CAPE for a few robust updrafts. Low and mid level winds are not particularly strong, and large scale forcing is weak. This should limit the overall organization and severity of storms, but a few cells may produce gusty winds and hail. ...SD... Water vapor imagery shows a mid-level shortwave trough over WY approaching SD. Forcing ahead of this feature will likely lead to scattered high-based showers and thunderstorms across eastern WY and western/central SD this afternoon and evening. There is some chance that a storm or two could produce locally damaging wind gusts. ..Hart/Thornton.. 04/21/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Mon Apr 21 2025 Valid 211630Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper OH Valley... Morning surface analysis and satellite imagery show a cold front sweeping eastward across OH. Considerable cloud cover is present ahead of the front, but a narrow corridor of heating immediately ahead of the front will allow a period of heating - promoting scattered thunderstorms. Low-level moisture is limited with dewpoints only in the 50s, and forecast soundings show CAPE values generally below 1000 J/kg. Nevertheless, strong low and mid-level winds and considerable vertical shear will promote a risk of a few organized/severe storms capable of damaging wind gusts and perhaps a tornado or two. Refer to upcoming MCD #511 for further details. ...LA/MS/AL/GA/TN... The aforementioned surface cold front extends southeastward across west TN. A relatively moist air mass is present ahead of the front from southeast LA into parts of MS/AL and middle/east TN, although considerable cloud cover will limit heating. Most 12z models suggest scattered thunderstorms will form in this zone during the late afternoon and evening, with sufficient CAPE for a few robust updrafts. Low and mid level winds are not particularly strong, and large scale forcing is weak. This should limit the overall organization and severity of storms, but a few cells may produce gusty winds and hail. ...SD... Water vapor imagery shows a mid-level shortwave trough over WY approaching SD. Forcing ahead of this feature will likely lead to scattered high-based showers and thunderstorms across eastern WY and western/central SD this afternoon and evening. There is some chance that a storm or two could produce locally damaging wind gusts. ..Hart/Thornton.. 04/21/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Mon Apr 21 2025 Valid 211630Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper OH Valley... Morning surface analysis and satellite imagery show a cold front sweeping eastward across OH. Considerable cloud cover is present ahead of the front, but a narrow corridor of heating immediately ahead of the front will allow a period of heating - promoting scattered thunderstorms. Low-level moisture is limited with dewpoints only in the 50s, and forecast soundings show CAPE values generally below 1000 J/kg. Nevertheless, strong low and mid-level winds and considerable vertical shear will promote a risk of a few organized/severe storms capable of damaging wind gusts and perhaps a tornado or two. Refer to upcoming MCD #511 for further details. ...LA/MS/AL/GA/TN... The aforementioned surface cold front extends southeastward across west TN. A relatively moist air mass is present ahead of the front from southeast LA into parts of MS/AL and middle/east TN, although considerable cloud cover will limit heating. Most 12z models suggest scattered thunderstorms will form in this zone during the late afternoon and evening, with sufficient CAPE for a few robust updrafts. Low and mid level winds are not particularly strong, and large scale forcing is weak. This should limit the overall organization and severity of storms, but a few cells may produce gusty winds and hail. ...SD... Water vapor imagery shows a mid-level shortwave trough over WY approaching SD. Forcing ahead of this feature will likely lead to scattered high-based showers and thunderstorms across eastern WY and western/central SD this afternoon and evening. There is some chance that a storm or two could produce locally damaging wind gusts. ..Hart/Thornton.. 04/21/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Mon Apr 21 2025 Valid 211630Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper OH Valley... Morning surface analysis and satellite imagery show a cold front sweeping eastward across OH. Considerable cloud cover is present ahead of the front, but a narrow corridor of heating immediately ahead of the front will allow a period of heating - promoting scattered thunderstorms. Low-level moisture is limited with dewpoints only in the 50s, and forecast soundings show CAPE values generally below 1000 J/kg. Nevertheless, strong low and mid-level winds and considerable vertical shear will promote a risk of a few organized/severe storms capable of damaging wind gusts and perhaps a tornado or two. Refer to upcoming MCD #511 for further details. ...LA/MS/AL/GA/TN... The aforementioned surface cold front extends southeastward across west TN. A relatively moist air mass is present ahead of the front from southeast LA into parts of MS/AL and middle/east TN, although considerable cloud cover will limit heating. Most 12z models suggest scattered thunderstorms will form in this zone during the late afternoon and evening, with sufficient CAPE for a few robust updrafts. Low and mid level winds are not particularly strong, and large scale forcing is weak. This should limit the overall organization and severity of storms, but a few cells may produce gusty winds and hail. ...SD... Water vapor imagery shows a mid-level shortwave trough over WY approaching SD. Forcing ahead of this feature will likely lead to scattered high-based showers and thunderstorms across eastern WY and western/central SD this afternoon and evening. There is some chance that a storm or two could produce locally damaging wind gusts. ..Hart/Thornton.. 04/21/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Mon Apr 21 2025 Valid 211630Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper OH Valley... Morning surface analysis and satellite imagery show a cold front sweeping eastward across OH. Considerable cloud cover is present ahead of the front, but a narrow corridor of heating immediately ahead of the front will allow a period of heating - promoting scattered thunderstorms. Low-level moisture is limited with dewpoints only in the 50s, and forecast soundings show CAPE values generally below 1000 J/kg. Nevertheless, strong low and mid-level winds and considerable vertical shear will promote a risk of a few organized/severe storms capable of damaging wind gusts and perhaps a tornado or two. Refer to upcoming MCD #511 for further details. ...LA/MS/AL/GA/TN... The aforementioned surface cold front extends southeastward across west TN. A relatively moist air mass is present ahead of the front from southeast LA into parts of MS/AL and middle/east TN, although considerable cloud cover will limit heating. Most 12z models suggest scattered thunderstorms will form in this zone during the late afternoon and evening, with sufficient CAPE for a few robust updrafts. Low and mid level winds are not particularly strong, and large scale forcing is weak. This should limit the overall organization and severity of storms, but a few cells may produce gusty winds and hail. ...SD... Water vapor imagery shows a mid-level shortwave trough over WY approaching SD. Forcing ahead of this feature will likely lead to scattered high-based showers and thunderstorms across eastern WY and western/central SD this afternoon and evening. There is some chance that a storm or two could produce locally damaging wind gusts. ..Hart/Thornton.. 04/21/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Mon Apr 21 2025 Valid 211630Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper OH Valley... Morning surface analysis and satellite imagery show a cold front sweeping eastward across OH. Considerable cloud cover is present ahead of the front, but a narrow corridor of heating immediately ahead of the front will allow a period of heating - promoting scattered thunderstorms. Low-level moisture is limited with dewpoints only in the 50s, and forecast soundings show CAPE values generally below 1000 J/kg. Nevertheless, strong low and mid-level winds and considerable vertical shear will promote a risk of a few organized/severe storms capable of damaging wind gusts and perhaps a tornado or two. Refer to upcoming MCD #511 for further details. ...LA/MS/AL/GA/TN... The aforementioned surface cold front extends southeastward across west TN. A relatively moist air mass is present ahead of the front from southeast LA into parts of MS/AL and middle/east TN, although considerable cloud cover will limit heating. Most 12z models suggest scattered thunderstorms will form in this zone during the late afternoon and evening, with sufficient CAPE for a few robust updrafts. Low and mid level winds are not particularly strong, and large scale forcing is weak. This should limit the overall organization and severity of storms, but a few cells may produce gusty winds and hail. ...SD... Water vapor imagery shows a mid-level shortwave trough over WY approaching SD. Forcing ahead of this feature will likely lead to scattered high-based showers and thunderstorms across eastern WY and western/central SD this afternoon and evening. There is some chance that a storm or two could produce locally damaging wind gusts. ..Hart/Thornton.. 04/21/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Mon Apr 21 2025 Valid 211630Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper OH Valley... Morning surface analysis and satellite imagery show a cold front sweeping eastward across OH. Considerable cloud cover is present ahead of the front, but a narrow corridor of heating immediately ahead of the front will allow a period of heating - promoting scattered thunderstorms. Low-level moisture is limited with dewpoints only in the 50s, and forecast soundings show CAPE values generally below 1000 J/kg. Nevertheless, strong low and mid-level winds and considerable vertical shear will promote a risk of a few organized/severe storms capable of damaging wind gusts and perhaps a tornado or two. Refer to upcoming MCD #511 for further details. ...LA/MS/AL/GA/TN... The aforementioned surface cold front extends southeastward across west TN. A relatively moist air mass is present ahead of the front from southeast LA into parts of MS/AL and middle/east TN, although considerable cloud cover will limit heating. Most 12z models suggest scattered thunderstorms will form in this zone during the late afternoon and evening, with sufficient CAPE for a few robust updrafts. Low and mid level winds are not particularly strong, and large scale forcing is weak. This should limit the overall organization and severity of storms, but a few cells may produce gusty winds and hail. ...SD... Water vapor imagery shows a mid-level shortwave trough over WY approaching SD. Forcing ahead of this feature will likely lead to scattered high-based showers and thunderstorms across eastern WY and western/central SD this afternoon and evening. There is some chance that a storm or two could produce locally damaging wind gusts. ..Hart/Thornton.. 04/21/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Mon Apr 21 2025 Valid 211630Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper OH Valley... Morning surface analysis and satellite imagery show a cold front sweeping eastward across OH. Considerable cloud cover is present ahead of the front, but a narrow corridor of heating immediately ahead of the front will allow a period of heating - promoting scattered thunderstorms. Low-level moisture is limited with dewpoints only in the 50s, and forecast soundings show CAPE values generally below 1000 J/kg. Nevertheless, strong low and mid-level winds and considerable vertical shear will promote a risk of a few organized/severe storms capable of damaging wind gusts and perhaps a tornado or two. Refer to upcoming MCD #511 for further details. ...LA/MS/AL/GA/TN... The aforementioned surface cold front extends southeastward across west TN. A relatively moist air mass is present ahead of the front from southeast LA into parts of MS/AL and middle/east TN, although considerable cloud cover will limit heating. Most 12z models suggest scattered thunderstorms will form in this zone during the late afternoon and evening, with sufficient CAPE for a few robust updrafts. Low and mid level winds are not particularly strong, and large scale forcing is weak. This should limit the overall organization and severity of storms, but a few cells may produce gusty winds and hail. ...SD... Water vapor imagery shows a mid-level shortwave trough over WY approaching SD. Forcing ahead of this feature will likely lead to scattered high-based showers and thunderstorms across eastern WY and western/central SD this afternoon and evening. There is some chance that a storm or two could produce locally damaging wind gusts. ..Hart/Thornton.. 04/21/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Mon Apr 21 2025 Valid 211630Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper OH Valley... Morning surface analysis and satellite imagery show a cold front sweeping eastward across OH. Considerable cloud cover is present ahead of the front, but a narrow corridor of heating immediately ahead of the front will allow a period of heating - promoting scattered thunderstorms. Low-level moisture is limited with dewpoints only in the 50s, and forecast soundings show CAPE values generally below 1000 J/kg. Nevertheless, strong low and mid-level winds and considerable vertical shear will promote a risk of a few organized/severe storms capable of damaging wind gusts and perhaps a tornado or two. Refer to upcoming MCD #511 for further details. ...LA/MS/AL/GA/TN... The aforementioned surface cold front extends southeastward across west TN. A relatively moist air mass is present ahead of the front from southeast LA into parts of MS/AL and middle/east TN, although considerable cloud cover will limit heating. Most 12z models suggest scattered thunderstorms will form in this zone during the late afternoon and evening, with sufficient CAPE for a few robust updrafts. Low and mid level winds are not particularly strong, and large scale forcing is weak. This should limit the overall organization and severity of storms, but a few cells may produce gusty winds and hail. ...SD... Water vapor imagery shows a mid-level shortwave trough over WY approaching SD. Forcing ahead of this feature will likely lead to scattered high-based showers and thunderstorms across eastern WY and western/central SD this afternoon and evening. There is some chance that a storm or two could produce locally damaging wind gusts. ..Hart/Thornton.. 04/21/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Mon Apr 21 2025 Valid 211630Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper OH Valley... Morning surface analysis and satellite imagery show a cold front sweeping eastward across OH. Considerable cloud cover is present ahead of the front, but a narrow corridor of heating immediately ahead of the front will allow a period of heating - promoting scattered thunderstorms. Low-level moisture is limited with dewpoints only in the 50s, and forecast soundings show CAPE values generally below 1000 J/kg. Nevertheless, strong low and mid-level winds and considerable vertical shear will promote a risk of a few organized/severe storms capable of damaging wind gusts and perhaps a tornado or two. Refer to upcoming MCD #511 for further details. ...LA/MS/AL/GA/TN... The aforementioned surface cold front extends southeastward across west TN. A relatively moist air mass is present ahead of the front from southeast LA into parts of MS/AL and middle/east TN, although considerable cloud cover will limit heating. Most 12z models suggest scattered thunderstorms will form in this zone during the late afternoon and evening, with sufficient CAPE for a few robust updrafts. Low and mid level winds are not particularly strong, and large scale forcing is weak. This should limit the overall organization and severity of storms, but a few cells may produce gusty winds and hail. ...SD... Water vapor imagery shows a mid-level shortwave trough over WY approaching SD. Forcing ahead of this feature will likely lead to scattered high-based showers and thunderstorms across eastern WY and western/central SD this afternoon and evening. There is some chance that a storm or two could produce locally damaging wind gusts. ..Hart/Thornton.. 04/21/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0730 AM CDT Mon Apr 21 2025 Valid 211300Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper Ohio Valley to the Lower Great Lakes... An upper trough with an attendant 55-70 kt mid-level jet will advance east-northeastward from the Upper Midwest across the Great Lakes and Northeast today. A related surface low will develop northeastward into Ontario/Quebec, while a cold front sweeps eastward over the OH Valley and parts of the Mid-Atlantic and Northeast through this evening. Modest low-level moisture will advect northward ahead of this front in tandem with a strong southwesterly low-level jet. Even though this moisture will remain somewhat limited, filtered daytime heating and cool mid-level temperatures should aid weak destabilization in a narrow corridor along/ahead of the front by early afternoon. Thunderstorms that develop along the front may pose an isolated severe/damaging wind threat this afternoon and early evening given the expected strength of the low/mid-level flow. Occasional hail may also be noted with the strongest cores, and sufficient low-level shear should exist to support a tornado or two. The Marginal Risk has been expanded northward/eastward some based on latest guidance trends regarding sufficient destabilization to support surface-based convection. ...Southeast... The trailing portion of the surface cold front should make only slow east-southeastward progress today across the Southeast. This region will have weaker low/mid-level winds compared to locations farther north. Still, around 500-1500 J/kg of MLCAPE should develop by this afternoon along/ahead of the front, while 25-35 kt of deep-layer shear aids in modest updraft organization. Any thunderstorms which develop in this regime could pose an isolated threat for marginally severe hail and damaging winds. This threat should peak by mid afternoon, before gradually diminishing through the evening with the loss of daytime heating. ...Northern Plains... Gusty winds may occur with high-based convection this afternoon as a shortwave trough moves eastward over the northern Plains. However, low-level moisture and instability are both expected to remain very meager, which should preclude an organized severe wind threat. ...Upper Midwest... Elevated thunderstorms may develop late tonight across parts of IA in a low-level warm advection regime. With MUCAPE forecast to remain less than 1000 J/kg, the potential for severe hail appears too limited to include low severe probabilities at this time. ..Gleason/Broyles.. 04/21/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0730 AM CDT Mon Apr 21 2025 Valid 211300Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper Ohio Valley to the Lower Great Lakes... An upper trough with an attendant 55-70 kt mid-level jet will advance east-northeastward from the Upper Midwest across the Great Lakes and Northeast today. A related surface low will develop northeastward into Ontario/Quebec, while a cold front sweeps eastward over the OH Valley and parts of the Mid-Atlantic and Northeast through this evening. Modest low-level moisture will advect northward ahead of this front in tandem with a strong southwesterly low-level jet. Even though this moisture will remain somewhat limited, filtered daytime heating and cool mid-level temperatures should aid weak destabilization in a narrow corridor along/ahead of the front by early afternoon. Thunderstorms that develop along the front may pose an isolated severe/damaging wind threat this afternoon and early evening given the expected strength of the low/mid-level flow. Occasional hail may also be noted with the strongest cores, and sufficient low-level shear should exist to support a tornado or two. The Marginal Risk has been expanded northward/eastward some based on latest guidance trends regarding sufficient destabilization to support surface-based convection. ...Southeast... The trailing portion of the surface cold front should make only slow east-southeastward progress today across the Southeast. This region will have weaker low/mid-level winds compared to locations farther north. Still, around 500-1500 J/kg of MLCAPE should develop by this afternoon along/ahead of the front, while 25-35 kt of deep-layer shear aids in modest updraft organization. Any thunderstorms which develop in this regime could pose an isolated threat for marginally severe hail and damaging winds. This threat should peak by mid afternoon, before gradually diminishing through the evening with the loss of daytime heating. ...Northern Plains... Gusty winds may occur with high-based convection this afternoon as a shortwave trough moves eastward over the northern Plains. However, low-level moisture and instability are both expected to remain very meager, which should preclude an organized severe wind threat. ...Upper Midwest... Elevated thunderstorms may develop late tonight across parts of IA in a low-level warm advection regime. With MUCAPE forecast to remain less than 1000 J/kg, the potential for severe hail appears too limited to include low severe probabilities at this time. ..Gleason/Broyles.. 04/21/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0730 AM CDT Mon Apr 21 2025 Valid 211300Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper Ohio Valley to the Lower Great Lakes... An upper trough with an attendant 55-70 kt mid-level jet will advance east-northeastward from the Upper Midwest across the Great Lakes and Northeast today. A related surface low will develop northeastward into Ontario/Quebec, while a cold front sweeps eastward over the OH Valley and parts of the Mid-Atlantic and Northeast through this evening. Modest low-level moisture will advect northward ahead of this front in tandem with a strong southwesterly low-level jet. Even though this moisture will remain somewhat limited, filtered daytime heating and cool mid-level temperatures should aid weak destabilization in a narrow corridor along/ahead of the front by early afternoon. Thunderstorms that develop along the front may pose an isolated severe/damaging wind threat this afternoon and early evening given the expected strength of the low/mid-level flow. Occasional hail may also be noted with the strongest cores, and sufficient low-level shear should exist to support a tornado or two. The Marginal Risk has been expanded northward/eastward some based on latest guidance trends regarding sufficient destabilization to support surface-based convection. ...Southeast... The trailing portion of the surface cold front should make only slow east-southeastward progress today across the Southeast. This region will have weaker low/mid-level winds compared to locations farther north. Still, around 500-1500 J/kg of MLCAPE should develop by this afternoon along/ahead of the front, while 25-35 kt of deep-layer shear aids in modest updraft organization. Any thunderstorms which develop in this regime could pose an isolated threat for marginally severe hail and damaging winds. This threat should peak by mid afternoon, before gradually diminishing through the evening with the loss of daytime heating. ...Northern Plains... Gusty winds may occur with high-based convection this afternoon as a shortwave trough moves eastward over the northern Plains. However, low-level moisture and instability are both expected to remain very meager, which should preclude an organized severe wind threat. ...Upper Midwest... Elevated thunderstorms may develop late tonight across parts of IA in a low-level warm advection regime. With MUCAPE forecast to remain less than 1000 J/kg, the potential for severe hail appears too limited to include low severe probabilities at this time. ..Gleason/Broyles.. 04/21/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0730 AM CDT Mon Apr 21 2025 Valid 211300Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper Ohio Valley to the Lower Great Lakes... An upper trough with an attendant 55-70 kt mid-level jet will advance east-northeastward from the Upper Midwest across the Great Lakes and Northeast today. A related surface low will develop northeastward into Ontario/Quebec, while a cold front sweeps eastward over the OH Valley and parts of the Mid-Atlantic and Northeast through this evening. Modest low-level moisture will advect northward ahead of this front in tandem with a strong southwesterly low-level jet. Even though this moisture will remain somewhat limited, filtered daytime heating and cool mid-level temperatures should aid weak destabilization in a narrow corridor along/ahead of the front by early afternoon. Thunderstorms that develop along the front may pose an isolated severe/damaging wind threat this afternoon and early evening given the expected strength of the low/mid-level flow. Occasional hail may also be noted with the strongest cores, and sufficient low-level shear should exist to support a tornado or two. The Marginal Risk has been expanded northward/eastward some based on latest guidance trends regarding sufficient destabilization to support surface-based convection. ...Southeast... The trailing portion of the surface cold front should make only slow east-southeastward progress today across the Southeast. This region will have weaker low/mid-level winds compared to locations farther north. Still, around 500-1500 J/kg of MLCAPE should develop by this afternoon along/ahead of the front, while 25-35 kt of deep-layer shear aids in modest updraft organization. Any thunderstorms which develop in this regime could pose an isolated threat for marginally severe hail and damaging winds. This threat should peak by mid afternoon, before gradually diminishing through the evening with the loss of daytime heating. ...Northern Plains... Gusty winds may occur with high-based convection this afternoon as a shortwave trough moves eastward over the northern Plains. However, low-level moisture and instability are both expected to remain very meager, which should preclude an organized severe wind threat. ...Upper Midwest... Elevated thunderstorms may develop late tonight across parts of IA in a low-level warm advection regime. With MUCAPE forecast to remain less than 1000 J/kg, the potential for severe hail appears too limited to include low severe probabilities at this time. ..Gleason/Broyles.. 04/21/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0730 AM CDT Mon Apr 21 2025 Valid 211300Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper Ohio Valley to the Lower Great Lakes... An upper trough with an attendant 55-70 kt mid-level jet will advance east-northeastward from the Upper Midwest across the Great Lakes and Northeast today. A related surface low will develop northeastward into Ontario/Quebec, while a cold front sweeps eastward over the OH Valley and parts of the Mid-Atlantic and Northeast through this evening. Modest low-level moisture will advect northward ahead of this front in tandem with a strong southwesterly low-level jet. Even though this moisture will remain somewhat limited, filtered daytime heating and cool mid-level temperatures should aid weak destabilization in a narrow corridor along/ahead of the front by early afternoon. Thunderstorms that develop along the front may pose an isolated severe/damaging wind threat this afternoon and early evening given the expected strength of the low/mid-level flow. Occasional hail may also be noted with the strongest cores, and sufficient low-level shear should exist to support a tornado or two. The Marginal Risk has been expanded northward/eastward some based on latest guidance trends regarding sufficient destabilization to support surface-based convection. ...Southeast... The trailing portion of the surface cold front should make only slow east-southeastward progress today across the Southeast. This region will have weaker low/mid-level winds compared to locations farther north. Still, around 500-1500 J/kg of MLCAPE should develop by this afternoon along/ahead of the front, while 25-35 kt of deep-layer shear aids in modest updraft organization. Any thunderstorms which develop in this regime could pose an isolated threat for marginally severe hail and damaging winds. This threat should peak by mid afternoon, before gradually diminishing through the evening with the loss of daytime heating. ...Northern Plains... Gusty winds may occur with high-based convection this afternoon as a shortwave trough moves eastward over the northern Plains. However, low-level moisture and instability are both expected to remain very meager, which should preclude an organized severe wind threat. ...Upper Midwest... Elevated thunderstorms may develop late tonight across parts of IA in a low-level warm advection regime. With MUCAPE forecast to remain less than 1000 J/kg, the potential for severe hail appears too limited to include low severe probabilities at this time. ..Gleason/Broyles.. 04/21/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0730 AM CDT Mon Apr 21 2025 Valid 211300Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES...AND PORTIONS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms are possible today across the upper Ohio Valley/lower Great Lakes and parts of the Southeast. Damaging winds and marginally severe hail are the primary risks. ...Upper Ohio Valley to the Lower Great Lakes... An upper trough with an attendant 55-70 kt mid-level jet will advance east-northeastward from the Upper Midwest across the Great Lakes and Northeast today. A related surface low will develop northeastward into Ontario/Quebec, while a cold front sweeps eastward over the OH Valley and parts of the Mid-Atlantic and Northeast through this evening. Modest low-level moisture will advect northward ahead of this front in tandem with a strong southwesterly low-level jet. Even though this moisture will remain somewhat limited, filtered daytime heating and cool mid-level temperatures should aid weak destabilization in a narrow corridor along/ahead of the front by early afternoon. Thunderstorms that develop along the front may pose an isolated severe/damaging wind threat this afternoon and early evening given the expected strength of the low/mid-level flow. Occasional hail may also be noted with the strongest cores, and sufficient low-level shear should exist to support a tornado or two. The Marginal Risk has been expanded northward/eastward some based on latest guidance trends regarding sufficient destabilization to support surface-based convection. ...Southeast... The trailing portion of the surface cold front should make only slow east-southeastward progress today across the Southeast. This region will have weaker low/mid-level winds compared to locations farther north. Still, around 500-1500 J/kg of MLCAPE should develop by this afternoon along/ahead of the front, while 25-35 kt of deep-layer shear aids in modest updraft organization. Any thunderstorms which develop in this regime could pose an isolated threat for marginally severe hail and damaging winds. This threat should peak by mid afternoon, before gradually diminishing through the evening with the loss of daytime heating. ...Northern Plains... Gusty winds may occur with high-based convection this afternoon as a shortwave trough moves eastward over the northern Plains. However, low-level moisture and instability are both expected to remain very meager, which should preclude an organized severe wind threat. ...Upper Midwest... Elevated thunderstorms may develop late tonight across parts of IA in a low-level warm advection regime. With MUCAPE forecast to remain less than 1000 J/kg, the potential for severe hail appears too limited to include low severe probabilities at this time. ..Gleason/Broyles.. 04/21/2025 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0307 AM CDT Mon Apr 21 2025 Valid 241200Z - 291200Z ...DISCUSSION... ...Day 4/Thu -- Central/Southern Plains... Some severe thunderstorm potential is possible across the southern/central Plains on Day 4/Thu. Similar to the Day 2-3/Tue-Wed period, a low-amplitude, and generally modest deep-layer southwesterly flow regime will persist. Southerly low level flow ahead of a southward sagging front across the central Plains, and to the east of a dryline extending southward across the southern High Plains will sustain advection of Gulf moisture across the region. At least some risk for isolated severe thunderstorms appears possible within the moist/unstable warm sector. However, convection may be ongoing across portions of the region Thursday morning, and given a lack of any stronger upper forcing regime or surface cyclogenesis, confidence in where greater severe potential may develop is low, precluding 15 percent delineation at this time. ...Days 5-6/Fri-Sat -- Southern Plains vicinity... Upper riding is forecast to overspread the Plains late in the week ahead of a deepening western U.S. upper trough. A cold front will sag south and east on Friday, extending from the Ohio Valley into the southern High Plains. As the upper ridge builds, richer Gulf moisture will develop across TX into OK. Some localized strong/severe storms may develop across west TX during this time within the moist upslope flow regime, but the upper ridge and weak forcing should suppress more widespread severe potential. ...Days 7-8/Sun-Mon -- Plains to the MS Valley... Severe potential is likely to increase from OK/TX into the central Plains/Mid-MO Valley by early next week as the western upper trough begins to eject eastward. This should result in stronger southwesterly mid/upper flow overspreading a broad warm sector. This overall pattern is a synoptically favorable spring time pattern for severe storms across the Plains. Furthermore, control members and ensemble members from the GFS and ECMWF are in fairly good agreement regarding the timing/location of the ejecting upper trough and stronger southwesterly flow overspreading the region. Nevertheless, uncertainty remains too high to include 15 percent delineated areas at this time. This is particularly the case of Day 7/Sun where forecast guidance has widespread precipitation ongoing during the morning. Given the otherwise favorable pattern, severe probabilities will likely be needed in the coming days as details become better refined. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0307 AM CDT Mon Apr 21 2025 Valid 241200Z - 291200Z ...DISCUSSION... ...Day 4/Thu -- Central/Southern Plains... Some severe thunderstorm potential is possible across the southern/central Plains on Day 4/Thu. Similar to the Day 2-3/Tue-Wed period, a low-amplitude, and generally modest deep-layer southwesterly flow regime will persist. Southerly low level flow ahead of a southward sagging front across the central Plains, and to the east of a dryline extending southward across the southern High Plains will sustain advection of Gulf moisture across the region. At least some risk for isolated severe thunderstorms appears possible within the moist/unstable warm sector. However, convection may be ongoing across portions of the region Thursday morning, and given a lack of any stronger upper forcing regime or surface cyclogenesis, confidence in where greater severe potential may develop is low, precluding 15 percent delineation at this time. ...Days 5-6/Fri-Sat -- Southern Plains vicinity... Upper riding is forecast to overspread the Plains late in the week ahead of a deepening western U.S. upper trough. A cold front will sag south and east on Friday, extending from the Ohio Valley into the southern High Plains. As the upper ridge builds, richer Gulf moisture will develop across TX into OK. Some localized strong/severe storms may develop across west TX during this time within the moist upslope flow regime, but the upper ridge and weak forcing should suppress more widespread severe potential. ...Days 7-8/Sun-Mon -- Plains to the MS Valley... Severe potential is likely to increase from OK/TX into the central Plains/Mid-MO Valley by early next week as the western upper trough begins to eject eastward. This should result in stronger southwesterly mid/upper flow overspreading a broad warm sector. This overall pattern is a synoptically favorable spring time pattern for severe storms across the Plains. Furthermore, control members and ensemble members from the GFS and ECMWF are in fairly good agreement regarding the timing/location of the ejecting upper trough and stronger southwesterly flow overspreading the region. Nevertheless, uncertainty remains too high to include 15 percent delineated areas at this time. This is particularly the case of Day 7/Sun where forecast guidance has widespread precipitation ongoing during the morning. Given the otherwise favorable pattern, severe probabilities will likely be needed in the coming days as details become better refined. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0307 AM CDT Mon Apr 21 2025 Valid 241200Z - 291200Z ...DISCUSSION... ...Day 4/Thu -- Central/Southern Plains... Some severe thunderstorm potential is possible across the southern/central Plains on Day 4/Thu. Similar to the Day 2-3/Tue-Wed period, a low-amplitude, and generally modest deep-layer southwesterly flow regime will persist. Southerly low level flow ahead of a southward sagging front across the central Plains, and to the east of a dryline extending southward across the southern High Plains will sustain advection of Gulf moisture across the region. At least some risk for isolated severe thunderstorms appears possible within the moist/unstable warm sector. However, convection may be ongoing across portions of the region Thursday morning, and given a lack of any stronger upper forcing regime or surface cyclogenesis, confidence in where greater severe potential may develop is low, precluding 15 percent delineation at this time. ...Days 5-6/Fri-Sat -- Southern Plains vicinity... Upper riding is forecast to overspread the Plains late in the week ahead of a deepening western U.S. upper trough. A cold front will sag south and east on Friday, extending from the Ohio Valley into the southern High Plains. As the upper ridge builds, richer Gulf moisture will develop across TX into OK. Some localized strong/severe storms may develop across west TX during this time within the moist upslope flow regime, but the upper ridge and weak forcing should suppress more widespread severe potential. ...Days 7-8/Sun-Mon -- Plains to the MS Valley... Severe potential is likely to increase from OK/TX into the central Plains/Mid-MO Valley by early next week as the western upper trough begins to eject eastward. This should result in stronger southwesterly mid/upper flow overspreading a broad warm sector. This overall pattern is a synoptically favorable spring time pattern for severe storms across the Plains. Furthermore, control members and ensemble members from the GFS and ECMWF are in fairly good agreement regarding the timing/location of the ejecting upper trough and stronger southwesterly flow overspreading the region. Nevertheless, uncertainty remains too high to include 15 percent delineated areas at this time. This is particularly the case of Day 7/Sun where forecast guidance has widespread precipitation ongoing during the morning. Given the otherwise favorable pattern, severe probabilities will likely be needed in the coming days as details become better refined. Read more