Severe Storms

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1226 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE OHIO AND TENNESSEE VALLEYS INTO THE CENTRAL APPALACHIANS... ...SUMMARY... Scattered thunderstorms capable of producing damaging wind gusts and isolated large hail are expected across parts of the Ohio and Tennessee Valleys into the Central Appalachians on Friday. ...Synopsis... A deep/vertically stacked cyclone will move gradually northward across Ontario toward Hudson Bay through the period, as an accompanying midlevel jet streak advances from the Great Lakes into Quebec. Peripheral to the deep cyclone, broad midlevel troughing will persist across much of the eastern CONUS. An accompanying cold front will extend from the Great Lakes region southwestward across the OH Valley into the southern Plains. Given the slowly evolving/amplified upper-level pattern, the cold front will only move gradually east-southeastward through the period. ...Ohio/Tennessee Valleys into the Central Appalachians... Ahead of the cold front, ample diurnal heating amid upper 60s dewpoints will contribute to a moderately unstable (around 2500 J/kg MLCAPE), uncapped pre-convective air mass. Potentially aided by a convectively augmented midlevel impulse approaching the OH Valley from the west, scattered thunderstorms should develop along/immediately ahead of the front during the afternoon into evening/overnight. The aforementioned buoyancy and around 30-40 kt of effective shear should promote convective organization into clusters/small line segments and perhaps transient supercell structures. The stronger/longer-lived storms will be capable of producing damaging wind gusts and isolated severe hail. The best overlap of moderate buoyancy (higher with southward extent) and favorable deep-layer shear (stronger with northward extent) should exist over KY and surrounding states, where a Slight Risk was added. ...Mid-South into the Southern Plains... The cold front will be oriented more west-east over this region, with the stronger deep shear confined to the cool side of the boundary. Additionally, convective initiation may occur later into the evening/overnight hours along the sharpening cold front. Nevertheless, moderate-strong buoyancy aided by steep deep-layer lapse rates will promote strong storms capable of producing locally damaging gusts and sporadic, marginally severe hail. ..Weinman.. 09/04/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1226 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE OHIO AND TENNESSEE VALLEYS INTO THE CENTRAL APPALACHIANS... ...SUMMARY... Scattered thunderstorms capable of producing damaging wind gusts and isolated large hail are expected across parts of the Ohio and Tennessee Valleys into the Central Appalachians on Friday. ...Synopsis... A deep/vertically stacked cyclone will move gradually northward across Ontario toward Hudson Bay through the period, as an accompanying midlevel jet streak advances from the Great Lakes into Quebec. Peripheral to the deep cyclone, broad midlevel troughing will persist across much of the eastern CONUS. An accompanying cold front will extend from the Great Lakes region southwestward across the OH Valley into the southern Plains. Given the slowly evolving/amplified upper-level pattern, the cold front will only move gradually east-southeastward through the period. ...Ohio/Tennessee Valleys into the Central Appalachians... Ahead of the cold front, ample diurnal heating amid upper 60s dewpoints will contribute to a moderately unstable (around 2500 J/kg MLCAPE), uncapped pre-convective air mass. Potentially aided by a convectively augmented midlevel impulse approaching the OH Valley from the west, scattered thunderstorms should develop along/immediately ahead of the front during the afternoon into evening/overnight. The aforementioned buoyancy and around 30-40 kt of effective shear should promote convective organization into clusters/small line segments and perhaps transient supercell structures. The stronger/longer-lived storms will be capable of producing damaging wind gusts and isolated severe hail. The best overlap of moderate buoyancy (higher with southward extent) and favorable deep-layer shear (stronger with northward extent) should exist over KY and surrounding states, where a Slight Risk was added. ...Mid-South into the Southern Plains... The cold front will be oriented more west-east over this region, with the stronger deep shear confined to the cool side of the boundary. Additionally, convective initiation may occur later into the evening/overnight hours along the sharpening cold front. Nevertheless, moderate-strong buoyancy aided by steep deep-layer lapse rates will promote strong storms capable of producing locally damaging gusts and sporadic, marginally severe hail. ..Weinman.. 09/04/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1226 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE OHIO AND TENNESSEE VALLEYS INTO THE CENTRAL APPALACHIANS... ...SUMMARY... Scattered thunderstorms capable of producing damaging wind gusts and isolated large hail are expected across parts of the Ohio and Tennessee Valleys into the Central Appalachians on Friday. ...Synopsis... A deep/vertically stacked cyclone will move gradually northward across Ontario toward Hudson Bay through the period, as an accompanying midlevel jet streak advances from the Great Lakes into Quebec. Peripheral to the deep cyclone, broad midlevel troughing will persist across much of the eastern CONUS. An accompanying cold front will extend from the Great Lakes region southwestward across the OH Valley into the southern Plains. Given the slowly evolving/amplified upper-level pattern, the cold front will only move gradually east-southeastward through the period. ...Ohio/Tennessee Valleys into the Central Appalachians... Ahead of the cold front, ample diurnal heating amid upper 60s dewpoints will contribute to a moderately unstable (around 2500 J/kg MLCAPE), uncapped pre-convective air mass. Potentially aided by a convectively augmented midlevel impulse approaching the OH Valley from the west, scattered thunderstorms should develop along/immediately ahead of the front during the afternoon into evening/overnight. The aforementioned buoyancy and around 30-40 kt of effective shear should promote convective organization into clusters/small line segments and perhaps transient supercell structures. The stronger/longer-lived storms will be capable of producing damaging wind gusts and isolated severe hail. The best overlap of moderate buoyancy (higher with southward extent) and favorable deep-layer shear (stronger with northward extent) should exist over KY and surrounding states, where a Slight Risk was added. ...Mid-South into the Southern Plains... The cold front will be oriented more west-east over this region, with the stronger deep shear confined to the cool side of the boundary. Additionally, convective initiation may occur later into the evening/overnight hours along the sharpening cold front. Nevertheless, moderate-strong buoyancy aided by steep deep-layer lapse rates will promote strong storms capable of producing locally damaging gusts and sporadic, marginally severe hail. ..Weinman.. 09/04/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1226 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE OHIO AND TENNESSEE VALLEYS INTO THE CENTRAL APPALACHIANS... ...SUMMARY... Scattered thunderstorms capable of producing damaging wind gusts and isolated large hail are expected across parts of the Ohio and Tennessee Valleys into the Central Appalachians on Friday. ...Synopsis... A deep/vertically stacked cyclone will move gradually northward across Ontario toward Hudson Bay through the period, as an accompanying midlevel jet streak advances from the Great Lakes into Quebec. Peripheral to the deep cyclone, broad midlevel troughing will persist across much of the eastern CONUS. An accompanying cold front will extend from the Great Lakes region southwestward across the OH Valley into the southern Plains. Given the slowly evolving/amplified upper-level pattern, the cold front will only move gradually east-southeastward through the period. ...Ohio/Tennessee Valleys into the Central Appalachians... Ahead of the cold front, ample diurnal heating amid upper 60s dewpoints will contribute to a moderately unstable (around 2500 J/kg MLCAPE), uncapped pre-convective air mass. Potentially aided by a convectively augmented midlevel impulse approaching the OH Valley from the west, scattered thunderstorms should develop along/immediately ahead of the front during the afternoon into evening/overnight. The aforementioned buoyancy and around 30-40 kt of effective shear should promote convective organization into clusters/small line segments and perhaps transient supercell structures. The stronger/longer-lived storms will be capable of producing damaging wind gusts and isolated severe hail. The best overlap of moderate buoyancy (higher with southward extent) and favorable deep-layer shear (stronger with northward extent) should exist over KY and surrounding states, where a Slight Risk was added. ...Mid-South into the Southern Plains... The cold front will be oriented more west-east over this region, with the stronger deep shear confined to the cool side of the boundary. Additionally, convective initiation may occur later into the evening/overnight hours along the sharpening cold front. Nevertheless, moderate-strong buoyancy aided by steep deep-layer lapse rates will promote strong storms capable of producing locally damaging gusts and sporadic, marginally severe hail. ..Weinman.. 09/04/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1226 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE OHIO AND TENNESSEE VALLEYS INTO THE CENTRAL APPALACHIANS... ...SUMMARY... Scattered thunderstorms capable of producing damaging wind gusts and isolated large hail are expected across parts of the Ohio and Tennessee Valleys into the Central Appalachians on Friday. ...Synopsis... A deep/vertically stacked cyclone will move gradually northward across Ontario toward Hudson Bay through the period, as an accompanying midlevel jet streak advances from the Great Lakes into Quebec. Peripheral to the deep cyclone, broad midlevel troughing will persist across much of the eastern CONUS. An accompanying cold front will extend from the Great Lakes region southwestward across the OH Valley into the southern Plains. Given the slowly evolving/amplified upper-level pattern, the cold front will only move gradually east-southeastward through the period. ...Ohio/Tennessee Valleys into the Central Appalachians... Ahead of the cold front, ample diurnal heating amid upper 60s dewpoints will contribute to a moderately unstable (around 2500 J/kg MLCAPE), uncapped pre-convective air mass. Potentially aided by a convectively augmented midlevel impulse approaching the OH Valley from the west, scattered thunderstorms should develop along/immediately ahead of the front during the afternoon into evening/overnight. The aforementioned buoyancy and around 30-40 kt of effective shear should promote convective organization into clusters/small line segments and perhaps transient supercell structures. The stronger/longer-lived storms will be capable of producing damaging wind gusts and isolated severe hail. The best overlap of moderate buoyancy (higher with southward extent) and favorable deep-layer shear (stronger with northward extent) should exist over KY and surrounding states, where a Slight Risk was added. ...Mid-South into the Southern Plains... The cold front will be oriented more west-east over this region, with the stronger deep shear confined to the cool side of the boundary. Additionally, convective initiation may occur later into the evening/overnight hours along the sharpening cold front. Nevertheless, moderate-strong buoyancy aided by steep deep-layer lapse rates will promote strong storms capable of producing locally damaging gusts and sporadic, marginally severe hail. ..Weinman.. 09/04/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1226 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE OHIO AND TENNESSEE VALLEYS INTO THE CENTRAL APPALACHIANS... ...SUMMARY... Scattered thunderstorms capable of producing damaging wind gusts and isolated large hail are expected across parts of the Ohio and Tennessee Valleys into the Central Appalachians on Friday. ...Synopsis... A deep/vertically stacked cyclone will move gradually northward across Ontario toward Hudson Bay through the period, as an accompanying midlevel jet streak advances from the Great Lakes into Quebec. Peripheral to the deep cyclone, broad midlevel troughing will persist across much of the eastern CONUS. An accompanying cold front will extend from the Great Lakes region southwestward across the OH Valley into the southern Plains. Given the slowly evolving/amplified upper-level pattern, the cold front will only move gradually east-southeastward through the period. ...Ohio/Tennessee Valleys into the Central Appalachians... Ahead of the cold front, ample diurnal heating amid upper 60s dewpoints will contribute to a moderately unstable (around 2500 J/kg MLCAPE), uncapped pre-convective air mass. Potentially aided by a convectively augmented midlevel impulse approaching the OH Valley from the west, scattered thunderstorms should develop along/immediately ahead of the front during the afternoon into evening/overnight. The aforementioned buoyancy and around 30-40 kt of effective shear should promote convective organization into clusters/small line segments and perhaps transient supercell structures. The stronger/longer-lived storms will be capable of producing damaging wind gusts and isolated severe hail. The best overlap of moderate buoyancy (higher with southward extent) and favorable deep-layer shear (stronger with northward extent) should exist over KY and surrounding states, where a Slight Risk was added. ...Mid-South into the Southern Plains... The cold front will be oriented more west-east over this region, with the stronger deep shear confined to the cool side of the boundary. Additionally, convective initiation may occur later into the evening/overnight hours along the sharpening cold front. Nevertheless, moderate-strong buoyancy aided by steep deep-layer lapse rates will promote strong storms capable of producing locally damaging gusts and sporadic, marginally severe hail. ..Weinman.. 09/04/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Thu Sep 04 2025 Valid 041630Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NEW YORK INTO THE MID-ATLANTIC AND TENNESSEE VALLEY...AND PORTIONS OF THE MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging winds may occur across parts of New York to the Mid-Atlantic and Tennessee Valley this afternoon. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. ..Gleason/Lyons.. 09/04/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Thu Sep 04 2025 Valid 041630Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NEW YORK INTO THE MID-ATLANTIC AND TENNESSEE VALLEY...AND PORTIONS OF THE MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging winds may occur across parts of New York to the Mid-Atlantic and Tennessee Valley this afternoon. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. ..Gleason/Lyons.. 09/04/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Thu Sep 04 2025 Valid 041630Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NEW YORK INTO THE MID-ATLANTIC AND TENNESSEE VALLEY...AND PORTIONS OF THE MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging winds may occur across parts of New York to the Mid-Atlantic and Tennessee Valley this afternoon. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. ..Gleason/Lyons.. 09/04/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Thu Sep 04 2025 Valid 041630Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NEW YORK INTO THE MID-ATLANTIC AND TENNESSEE VALLEY...AND PORTIONS OF THE MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging winds may occur across parts of New York to the Mid-Atlantic and Tennessee Valley this afternoon. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. ..Gleason/Lyons.. 09/04/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Thu Sep 04 2025 Valid 041630Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NEW YORK INTO THE MID-ATLANTIC AND TENNESSEE VALLEY...AND PORTIONS OF THE MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging winds may occur across parts of New York to the Mid-Atlantic and Tennessee Valley this afternoon. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. ..Gleason/Lyons.. 09/04/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Thu Sep 04 2025 Valid 041630Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NEW YORK INTO THE MID-ATLANTIC AND TENNESSEE VALLEY...AND PORTIONS OF THE MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging winds may occur across parts of New York to the Mid-Atlantic and Tennessee Valley this afternoon. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. ..Gleason/Lyons.. 09/04/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Thu Sep 04 2025 Valid 041630Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NEW YORK INTO THE MID-ATLANTIC AND TENNESSEE VALLEY...AND PORTIONS OF THE MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging winds may occur across parts of New York to the Mid-Atlantic and Tennessee Valley this afternoon. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. ..Gleason/Lyons.. 09/04/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Thu Sep 04 2025 Valid 041630Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NEW YORK INTO THE MID-ATLANTIC AND TENNESSEE VALLEY...AND PORTIONS OF THE MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging winds may occur across parts of New York to the Mid-Atlantic and Tennessee Valley this afternoon. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. ..Gleason/Lyons.. 09/04/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Thu Sep 04 2025 Valid 041630Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NEW YORK INTO THE MID-ATLANTIC AND TENNESSEE VALLEY...AND PORTIONS OF THE MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging winds may occur across parts of New York to the Mid-Atlantic and Tennessee Valley this afternoon. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. ..Gleason/Lyons.. 09/04/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Thu Sep 04 2025 Valid 041630Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NEW YORK INTO THE MID-ATLANTIC AND TENNESSEE VALLEY...AND PORTIONS OF THE MID MISSOURI VALLEY... ...SUMMARY... Isolated damaging winds may occur across parts of New York to the Mid-Atlantic and Tennessee Valley this afternoon. Isolated severe gusts are also possible across parts of the mid Missouri Valley late this afternoon and early evening. ...New York into the Mid-Atlantic and Tennessee Valley... A closed mid/upper-level low will remain centered over Ontario today. Multiple mid-level perturbations will rotate around this feature through the period, including a shortwave trough forecast to advance generally east-northeastward across parts of the central Appalachians/Mid-Atlantic into the Northeast. Showers and thunderstorms are ongoing mainly ahead of a surface cold front from parts of western NY southward to the TN Valley in a low/mid-level moisture plume. Generally clear skies ahead of this activity should allow for ample daytime heating of a modestly moistened low-level airmass. Even so, 12Z observed soundings from BUF, IAD, and RNK/GSO show rather poor mid-level lapse rates, which will likely hinder updraft strength even as weak instability develops this afternoon with continued diurnal heating. Modestly enhanced southwesterly low/mid-level flow should still aid in some thunderstorm organization even with the apparent thermodynamic limitations, with multicells the dominant convective mode. Wherever low-level lapse rates can become steepened, a risk for at least isolated damaging winds remains apparent. Some hail may also occur with the strongest cores across parts of the TN Valley/southern Appalachians where locally greater instability should be present this afternoon. The Marginal Risk has been adjusted for ongoing trends, but the potential for a more focused corridor of scattered severe/damaging winds remains unclear. ...Mid Missouri Valley... A mid-level shortwave trough and attendant strong speed maximum will move quickly southeastward today from central Canada and the northern Plains towards the mid MO Valley and vicinity. Pronounced ascent associated with this jet should encourage convection to develop by late this afternoon across parts of eastern SD and vicinity. While low-level moisture and MLCAPE are both expected to remain very limited, enhanced low/mid-level northwesterly flow may still support some risk for severe gusts with any low-topped convection that can develop and spread quickly southeastward before weakening this evening with the loss of daytime heating. ...Kansas... A sharp cold front will sweep southward across the central Plains tonight. Elevated convection should form to the cool side of this boundary late tonight through early Friday morning given sufficient MUCAPE. Locally strong surface gusts and small hail may accompany this activity amid robust low-level northerlies, but the overall severe potential should remain fairly low given the tendency for convection to be mostly elevated. ...Arizona/Lower Colorado River Valley... Thunderstorms should develop again today across parts of central/southern AZ and the lower CO River Valley, beneath weak mid-level flow and on the periphery of increasing mid-level moisture associated with Tropical Storm Lorena. Weak shear should keep thunderstorms mostly disorganized, but occasional strong/gusty winds may occur where low-level lapse rates can become steepened. ..Gleason/Lyons.. 09/04/2025 Read more

MD 2030 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR WESTERN INTO CENTRAL NEW YORK STATE...ADJACENT NORTHWESTERN INTO NORTH CENTRAL PENNSYLVANIA
Mesoscale Discussion 2030 NWS Storm Prediction Center Norman OK 0944 AM CDT Thu Sep 04 2025 Areas affected...western into central New York State...adjacent northwestern into north central Pennsylvania Concerning...Severe potential...Watch unlikely Valid 041444Z - 041645Z Probability of Watch Issuance...20 percent SUMMARY...One or two developing bands of showers and thunderstorms may pose increasing potential for sporadic wind damage through early afternoon. This currently seems unlikely to require a severe weather watch, but trends will be monitored. DISCUSSION...Boundary layer warming associated with insolation is beginning to contribute to destabilization in a pre-frontal corridor, where the latest Rapid Refresh suggests that mid-level forcing for ascent, associated with a short wave perturbation pivoting through the lower Great Lakes region, may contribute to deepening convective development through 16-18Z. Based on forecast soundings, although mid/upper lapse rates are likely to remain weak, sufficient boundary warming may occur for destabilization through favorably cold levels of the mixed-phase layer to support charge separation and increasing potential for scattered thunderstorm development. It is possible that this activity could gradually consolidate into an increasingly prominent line, which will tend to propagate ahead of the eastward advancing cold front. Although this may maintain a significant component parallel to the 30-40 kt south-southwesterly cloud-bearing layer mean flow, the deepening preceding well-mixed boundary-layer may gradually become increasingly conducive to downward momentum transfer to the surface. Peak gusts probably will tend to remain mostly below severe limits, but sporadic wind damage, particularly to trees, is possible. ..Kerr/Gleason.. 09/04/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BTV...BGM...BUF...CTP...PBZ... LAT...LON 44287528 42367618 41017871 41467913 43617840 44287528 MOST PROBABLE PEAK WIND GUST...55-70 MPH Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1018 AM CDT Thu Sep 04 2025 Valid 041700Z - 051200Z The IsoDryT area was expanded in portions of northern California, Oregon, and into the Washington Cascades based on the latest high-resolution forecast guidance. Additionally, deep pyroconvection was observed on four different fires in the Northwest yesterday, including lightning from it on the Wildcat and Lower Sugarloaf Fires in Washington. Deep pyroconvection remains possible on active large wildfires across the Northwest and into north Idaho and northwest California today, although smoke and cloud cover may help mitigate. Isolated high-based thunderstorms are possible overnight in portions of western/central Oregon. As a cold front pushes south into the northern Rockies, northeast-easterly winds will increase across western Montana, north Idaho, and eastern Washington this evening and overnight. Gusty winds of 20-35 mph are likely but RH is forecast to be 30-50%. Given the amount of fire activity, gusty winds, and wind shift, there is concern for increased activity from locally elevated conditions. Locally elevated conditions are also possible across portions of New England today in a pre-frontal environment. Southerly winds of 10-20 mph amid minimum RH of 35-50% are forecast this afternoon, and fuels are currently very dry in portions of New England. However, showers and thunderstorms with increasing RH will arrive this evening and overnight for much of New England. ..Nauslar.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1247 AM CDT Thu Sep 04 2025/ ...Synopsis... A departing mid-level wave will aid in thunderstorm development across portions of northern California into Washington this afternoon. Storm motions today will be slower than in recent days. A mix of wet/dry thunderstorms is expected. However, mainly mid-level moisture and dry sub-cloud layer should reduce rainfall amounts and increase potential for dry lightning strikes to occur. Activity over the last 24-48 hours has generally produced 0.25" of rain with several new fires detected. An area of isolated dry thunderstorm risk was maintained across portions of northern California into central Oregon with this outlook. A strike or two may extend as far north as the Washington Cascades. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1018 AM CDT Thu Sep 04 2025 Valid 041700Z - 051200Z The IsoDryT area was expanded in portions of northern California, Oregon, and into the Washington Cascades based on the latest high-resolution forecast guidance. Additionally, deep pyroconvection was observed on four different fires in the Northwest yesterday, including lightning from it on the Wildcat and Lower Sugarloaf Fires in Washington. Deep pyroconvection remains possible on active large wildfires across the Northwest and into north Idaho and northwest California today, although smoke and cloud cover may help mitigate. Isolated high-based thunderstorms are possible overnight in portions of western/central Oregon. As a cold front pushes south into the northern Rockies, northeast-easterly winds will increase across western Montana, north Idaho, and eastern Washington this evening and overnight. Gusty winds of 20-35 mph are likely but RH is forecast to be 30-50%. Given the amount of fire activity, gusty winds, and wind shift, there is concern for increased activity from locally elevated conditions. Locally elevated conditions are also possible across portions of New England today in a pre-frontal environment. Southerly winds of 10-20 mph amid minimum RH of 35-50% are forecast this afternoon, and fuels are currently very dry in portions of New England. However, showers and thunderstorms with increasing RH will arrive this evening and overnight for much of New England. ..Nauslar.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1247 AM CDT Thu Sep 04 2025/ ...Synopsis... A departing mid-level wave will aid in thunderstorm development across portions of northern California into Washington this afternoon. Storm motions today will be slower than in recent days. A mix of wet/dry thunderstorms is expected. However, mainly mid-level moisture and dry sub-cloud layer should reduce rainfall amounts and increase potential for dry lightning strikes to occur. Activity over the last 24-48 hours has generally produced 0.25" of rain with several new fires detected. An area of isolated dry thunderstorm risk was maintained across portions of northern California into central Oregon with this outlook. A strike or two may extend as far north as the Washington Cascades. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1018 AM CDT Thu Sep 04 2025 Valid 041700Z - 051200Z The IsoDryT area was expanded in portions of northern California, Oregon, and into the Washington Cascades based on the latest high-resolution forecast guidance. Additionally, deep pyroconvection was observed on four different fires in the Northwest yesterday, including lightning from it on the Wildcat and Lower Sugarloaf Fires in Washington. Deep pyroconvection remains possible on active large wildfires across the Northwest and into north Idaho and northwest California today, although smoke and cloud cover may help mitigate. Isolated high-based thunderstorms are possible overnight in portions of western/central Oregon. As a cold front pushes south into the northern Rockies, northeast-easterly winds will increase across western Montana, north Idaho, and eastern Washington this evening and overnight. Gusty winds of 20-35 mph are likely but RH is forecast to be 30-50%. Given the amount of fire activity, gusty winds, and wind shift, there is concern for increased activity from locally elevated conditions. Locally elevated conditions are also possible across portions of New England today in a pre-frontal environment. Southerly winds of 10-20 mph amid minimum RH of 35-50% are forecast this afternoon, and fuels are currently very dry in portions of New England. However, showers and thunderstorms with increasing RH will arrive this evening and overnight for much of New England. ..Nauslar.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1247 AM CDT Thu Sep 04 2025/ ...Synopsis... A departing mid-level wave will aid in thunderstorm development across portions of northern California into Washington this afternoon. Storm motions today will be slower than in recent days. A mix of wet/dry thunderstorms is expected. However, mainly mid-level moisture and dry sub-cloud layer should reduce rainfall amounts and increase potential for dry lightning strikes to occur. Activity over the last 24-48 hours has generally produced 0.25" of rain with several new fires detected. An area of isolated dry thunderstorm risk was maintained across portions of northern California into central Oregon with this outlook. A strike or two may extend as far north as the Washington Cascades. ...Please see www.spc.noaa.gov/fire for graphic product... Read more