Severe Storms

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1005 AM CDT Tue Aug 19 2025 Valid 191700Z - 201200Z Very low RH will continue across much of the Great Basin, West Slope, northern/western Arizona, western Wyoming, and southwest Montana and remaining below Elevated thresholds for 18-24 hours during the outlook period. This will lead to long burning periods once again, and multiple large fires remained active last night in similar conditions. Minor modifications were made to the Elevated area based on the latest observations and high-resolution forecast guidance. Dry thunderstorms are possible in portions of north-central and northeast Arizona on the fringe of monsoonal moisture. However, PWAT values and dewpoints increase slightly today while deeper moisture is expected in the coming days precluding an IsoDryT area. ..Nauslar.. 08/19/2025 .PREV DISCUSSION... /ISSUED 0156 AM CDT Tue Aug 19 2025/ ...Synopsis... An amplifying mid-level ridge over the Four Corners region will support a large area of hot and dry conditions over much of the Intermountain West. On the northern periphery of the ridge, southwesterly flow aloft will increase ahead of a shortwave trough. This will allow a dry cold front to approach and stall over the northwestern Great Basin. Ahead of the front, very warm and dry conditions are expected. With the increased flow aloft, forecast guidance shows south-southwest surface winds increasing to around 15 mph with gusts to 20-25 mph. The stronger winds amid a very dry airmass will support minimum RH of 5-15%. With regional fuels very dry, elevated fire-weather conditions appear likely. ...Northern Rockies... To the northwest, the mid-level trough and remnant monsoon moisture may support isolated thunderstorm potential across the higher terrain of the northern Rockies. Some lightning is possible, though the highest storm chances are expected over western MT and northeastern ID where less receptive fuels are present. This suggests the threat for ignitions is modest and below 10% coverage for IsoDryT highlights. ...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 1005 AM CDT Tue Aug 19 2025 Valid 191700Z - 201200Z Very low RH will continue across much of the Great Basin, West Slope, northern/western Arizona, western Wyoming, and southwest Montana and remaining below Elevated thresholds for 18-24 hours during the outlook period. This will lead to long burning periods once again, and multiple large fires remained active last night in similar conditions. Minor modifications were made to the Elevated area based on the latest observations and high-resolution forecast guidance. Dry thunderstorms are possible in portions of north-central and northeast Arizona on the fringe of monsoonal moisture. However, PWAT values and dewpoints increase slightly today while deeper moisture is expected in the coming days precluding an IsoDryT area. ..Nauslar.. 08/19/2025 .PREV DISCUSSION... /ISSUED 0156 AM CDT Tue Aug 19 2025/ ...Synopsis... An amplifying mid-level ridge over the Four Corners region will support a large area of hot and dry conditions over much of the Intermountain West. On the northern periphery of the ridge, southwesterly flow aloft will increase ahead of a shortwave trough. This will allow a dry cold front to approach and stall over the northwestern Great Basin. Ahead of the front, very warm and dry conditions are expected. With the increased flow aloft, forecast guidance shows south-southwest surface winds increasing to around 15 mph with gusts to 20-25 mph. The stronger winds amid a very dry airmass will support minimum RH of 5-15%. With regional fuels very dry, elevated fire-weather conditions appear likely. ...Northern Rockies... To the northwest, the mid-level trough and remnant monsoon moisture may support isolated thunderstorm potential across the higher terrain of the northern Rockies. Some lightning is possible, though the highest storm chances are expected over western MT and northeastern ID where less receptive fuels are present. This suggests the threat for ignitions is modest and below 10% coverage for IsoDryT highlights. ...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 1005 AM CDT Tue Aug 19 2025 Valid 191700Z - 201200Z Very low RH will continue across much of the Great Basin, West Slope, northern/western Arizona, western Wyoming, and southwest Montana and remaining below Elevated thresholds for 18-24 hours during the outlook period. This will lead to long burning periods once again, and multiple large fires remained active last night in similar conditions. Minor modifications were made to the Elevated area based on the latest observations and high-resolution forecast guidance. Dry thunderstorms are possible in portions of north-central and northeast Arizona on the fringe of monsoonal moisture. However, PWAT values and dewpoints increase slightly today while deeper moisture is expected in the coming days precluding an IsoDryT area. ..Nauslar.. 08/19/2025 .PREV DISCUSSION... /ISSUED 0156 AM CDT Tue Aug 19 2025/ ...Synopsis... An amplifying mid-level ridge over the Four Corners region will support a large area of hot and dry conditions over much of the Intermountain West. On the northern periphery of the ridge, southwesterly flow aloft will increase ahead of a shortwave trough. This will allow a dry cold front to approach and stall over the northwestern Great Basin. Ahead of the front, very warm and dry conditions are expected. With the increased flow aloft, forecast guidance shows south-southwest surface winds increasing to around 15 mph with gusts to 20-25 mph. The stronger winds amid a very dry airmass will support minimum RH of 5-15%. With regional fuels very dry, elevated fire-weather conditions appear likely. ...Northern Rockies... To the northwest, the mid-level trough and remnant monsoon moisture may support isolated thunderstorm potential across the higher terrain of the northern Rockies. Some lightning is possible, though the highest storm chances are expected over western MT and northeastern ID where less receptive fuels are present. This suggests the threat for ignitions is modest and below 10% coverage for IsoDryT highlights. ...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 1005 AM CDT Tue Aug 19 2025 Valid 191700Z - 201200Z Very low RH will continue across much of the Great Basin, West Slope, northern/western Arizona, western Wyoming, and southwest Montana and remaining below Elevated thresholds for 18-24 hours during the outlook period. This will lead to long burning periods once again, and multiple large fires remained active last night in similar conditions. Minor modifications were made to the Elevated area based on the latest observations and high-resolution forecast guidance. Dry thunderstorms are possible in portions of north-central and northeast Arizona on the fringe of monsoonal moisture. However, PWAT values and dewpoints increase slightly today while deeper moisture is expected in the coming days precluding an IsoDryT area. ..Nauslar.. 08/19/2025 .PREV DISCUSSION... /ISSUED 0156 AM CDT Tue Aug 19 2025/ ...Synopsis... An amplifying mid-level ridge over the Four Corners region will support a large area of hot and dry conditions over much of the Intermountain West. On the northern periphery of the ridge, southwesterly flow aloft will increase ahead of a shortwave trough. This will allow a dry cold front to approach and stall over the northwestern Great Basin. Ahead of the front, very warm and dry conditions are expected. With the increased flow aloft, forecast guidance shows south-southwest surface winds increasing to around 15 mph with gusts to 20-25 mph. The stronger winds amid a very dry airmass will support minimum RH of 5-15%. With regional fuels very dry, elevated fire-weather conditions appear likely. ...Northern Rockies... To the northwest, the mid-level trough and remnant monsoon moisture may support isolated thunderstorm potential across the higher terrain of the northern Rockies. Some lightning is possible, though the highest storm chances are expected over western MT and northeastern ID where less receptive fuels are present. This suggests the threat for ignitions is modest and below 10% coverage for IsoDryT highlights. ...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 1005 AM CDT Tue Aug 19 2025 Valid 191700Z - 201200Z Very low RH will continue across much of the Great Basin, West Slope, northern/western Arizona, western Wyoming, and southwest Montana and remaining below Elevated thresholds for 18-24 hours during the outlook period. This will lead to long burning periods once again, and multiple large fires remained active last night in similar conditions. Minor modifications were made to the Elevated area based on the latest observations and high-resolution forecast guidance. Dry thunderstorms are possible in portions of north-central and northeast Arizona on the fringe of monsoonal moisture. However, PWAT values and dewpoints increase slightly today while deeper moisture is expected in the coming days precluding an IsoDryT area. ..Nauslar.. 08/19/2025 .PREV DISCUSSION... /ISSUED 0156 AM CDT Tue Aug 19 2025/ ...Synopsis... An amplifying mid-level ridge over the Four Corners region will support a large area of hot and dry conditions over much of the Intermountain West. On the northern periphery of the ridge, southwesterly flow aloft will increase ahead of a shortwave trough. This will allow a dry cold front to approach and stall over the northwestern Great Basin. Ahead of the front, very warm and dry conditions are expected. With the increased flow aloft, forecast guidance shows south-southwest surface winds increasing to around 15 mph with gusts to 20-25 mph. The stronger winds amid a very dry airmass will support minimum RH of 5-15%. With regional fuels very dry, elevated fire-weather conditions appear likely. ...Northern Rockies... To the northwest, the mid-level trough and remnant monsoon moisture may support isolated thunderstorm potential across the higher terrain of the northern Rockies. Some lightning is possible, though the highest storm chances are expected over western MT and northeastern ID where less receptive fuels are present. This suggests the threat for ignitions is modest and below 10% coverage for IsoDryT highlights. ...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 1005 AM CDT Tue Aug 19 2025 Valid 191700Z - 201200Z Very low RH will continue across much of the Great Basin, West Slope, northern/western Arizona, western Wyoming, and southwest Montana and remaining below Elevated thresholds for 18-24 hours during the outlook period. This will lead to long burning periods once again, and multiple large fires remained active last night in similar conditions. Minor modifications were made to the Elevated area based on the latest observations and high-resolution forecast guidance. Dry thunderstorms are possible in portions of north-central and northeast Arizona on the fringe of monsoonal moisture. However, PWAT values and dewpoints increase slightly today while deeper moisture is expected in the coming days precluding an IsoDryT area. ..Nauslar.. 08/19/2025 .PREV DISCUSSION... /ISSUED 0156 AM CDT Tue Aug 19 2025/ ...Synopsis... An amplifying mid-level ridge over the Four Corners region will support a large area of hot and dry conditions over much of the Intermountain West. On the northern periphery of the ridge, southwesterly flow aloft will increase ahead of a shortwave trough. This will allow a dry cold front to approach and stall over the northwestern Great Basin. Ahead of the front, very warm and dry conditions are expected. With the increased flow aloft, forecast guidance shows south-southwest surface winds increasing to around 15 mph with gusts to 20-25 mph. The stronger winds amid a very dry airmass will support minimum RH of 5-15%. With regional fuels very dry, elevated fire-weather conditions appear likely. ...Northern Rockies... To the northwest, the mid-level trough and remnant monsoon moisture may support isolated thunderstorm potential across the higher terrain of the northern Rockies. Some lightning is possible, though the highest storm chances are expected over western MT and northeastern ID where less receptive fuels are present. This suggests the threat for ignitions is modest and below 10% coverage for IsoDryT highlights. ...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 1005 AM CDT Tue Aug 19 2025 Valid 191700Z - 201200Z Very low RH will continue across much of the Great Basin, West Slope, northern/western Arizona, western Wyoming, and southwest Montana and remaining below Elevated thresholds for 18-24 hours during the outlook period. This will lead to long burning periods once again, and multiple large fires remained active last night in similar conditions. Minor modifications were made to the Elevated area based on the latest observations and high-resolution forecast guidance. Dry thunderstorms are possible in portions of north-central and northeast Arizona on the fringe of monsoonal moisture. However, PWAT values and dewpoints increase slightly today while deeper moisture is expected in the coming days precluding an IsoDryT area. ..Nauslar.. 08/19/2025 .PREV DISCUSSION... /ISSUED 0156 AM CDT Tue Aug 19 2025/ ...Synopsis... An amplifying mid-level ridge over the Four Corners region will support a large area of hot and dry conditions over much of the Intermountain West. On the northern periphery of the ridge, southwesterly flow aloft will increase ahead of a shortwave trough. This will allow a dry cold front to approach and stall over the northwestern Great Basin. Ahead of the front, very warm and dry conditions are expected. With the increased flow aloft, forecast guidance shows south-southwest surface winds increasing to around 15 mph with gusts to 20-25 mph. The stronger winds amid a very dry airmass will support minimum RH of 5-15%. With regional fuels very dry, elevated fire-weather conditions appear likely. ...Northern Rockies... To the northwest, the mid-level trough and remnant monsoon moisture may support isolated thunderstorm potential across the higher terrain of the northern Rockies. Some lightning is possible, though the highest storm chances are expected over western MT and northeastern ID where less receptive fuels are present. This suggests the threat for ignitions is modest and below 10% coverage for IsoDryT highlights. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Tue Aug 19 2025 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTH-CENTRAL PLAINS AND OZARKS TO OHIO VALLEY AND NORTHERN ROCKIES... ...SUMMARY... Scattered strong to severe thunderstorms capable of damaging winds will be possible across the south-central Great Plains and Ozarks to the Ohio Valley this afternoon and evening. Isolated severe thunderstorms may also occur across parts of the northern Rockies including western and northern Montana. ...South-central Plains and Ozarks to Ohio Valley... Outside of a few areas of lingering early day convection/small-scale outflows, a hot air mass and relatively high moisture content will reside to the south of a synoptic front extending from the south-central Plains to the Midwest/Ohio Valley. Moderate to strong buoyancy with daytime heating, beneath a residual plume of relatively steep lower/mid-tropospheric lapse rates, will exist particularly across parts of the south-central Plains to Ozark Plateau, including parts of Kansas/Oklahoma to Arkansas/southern Missouri. As storms diurnally develop/increase, upscale-growing thunderstorm development should occur during the mid to late afternoon and early evening. While weak deep-layer winds and shear are likely to limit the risk for organized severe convection, thermodynamic profiles will be conducive for downbursts and severe-caliber wind gusts with the stronger storms, particularly this afternoon through around sunset. ...Northern Rockies including western/northern Montana... The late-day arrival of weak height falls and approaching mid-level perturbation should influence isolated thunderstorm development late this afternoon, and more so into this evening, across parts of northern Idaho in western and eventually northern Montana. Sufficient moisture/buoyancy near and behind a surface front, along with strengthening flow aloft, will support the possibility of some severe storms, and potentially some clustering/organization to the storms as they progress across western/northern Montana. West-southwesterly mean flow strengthening to 30-40+ kt in the cloud-bearing layer, and a residual deep sub-cloud mixed-layer, will likely be sufficient for downward mixing of momentum to contribute to a few strong to severe wind gusts. ..Guyer/Dean.. 08/19/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Tue Aug 19 2025 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTH-CENTRAL PLAINS AND OZARKS TO OHIO VALLEY AND NORTHERN ROCKIES... ...SUMMARY... Scattered strong to severe thunderstorms capable of damaging winds will be possible across the south-central Great Plains and Ozarks to the Ohio Valley this afternoon and evening. Isolated severe thunderstorms may also occur across parts of the northern Rockies including western and northern Montana. ...South-central Plains and Ozarks to Ohio Valley... Outside of a few areas of lingering early day convection/small-scale outflows, a hot air mass and relatively high moisture content will reside to the south of a synoptic front extending from the south-central Plains to the Midwest/Ohio Valley. Moderate to strong buoyancy with daytime heating, beneath a residual plume of relatively steep lower/mid-tropospheric lapse rates, will exist particularly across parts of the south-central Plains to Ozark Plateau, including parts of Kansas/Oklahoma to Arkansas/southern Missouri. As storms diurnally develop/increase, upscale-growing thunderstorm development should occur during the mid to late afternoon and early evening. While weak deep-layer winds and shear are likely to limit the risk for organized severe convection, thermodynamic profiles will be conducive for downbursts and severe-caliber wind gusts with the stronger storms, particularly this afternoon through around sunset. ...Northern Rockies including western/northern Montana... The late-day arrival of weak height falls and approaching mid-level perturbation should influence isolated thunderstorm development late this afternoon, and more so into this evening, across parts of northern Idaho in western and eventually northern Montana. Sufficient moisture/buoyancy near and behind a surface front, along with strengthening flow aloft, will support the possibility of some severe storms, and potentially some clustering/organization to the storms as they progress across western/northern Montana. West-southwesterly mean flow strengthening to 30-40+ kt in the cloud-bearing layer, and a residual deep sub-cloud mixed-layer, will likely be sufficient for downward mixing of momentum to contribute to a few strong to severe wind gusts. ..Guyer/Dean.. 08/19/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Tue Aug 19 2025 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTH-CENTRAL PLAINS AND OZARKS TO OHIO VALLEY AND NORTHERN ROCKIES... ...SUMMARY... Scattered strong to severe thunderstorms capable of damaging winds will be possible across the south-central Great Plains and Ozarks to the Ohio Valley this afternoon and evening. Isolated severe thunderstorms may also occur across parts of the northern Rockies including western and northern Montana. ...South-central Plains and Ozarks to Ohio Valley... Outside of a few areas of lingering early day convection/small-scale outflows, a hot air mass and relatively high moisture content will reside to the south of a synoptic front extending from the south-central Plains to the Midwest/Ohio Valley. Moderate to strong buoyancy with daytime heating, beneath a residual plume of relatively steep lower/mid-tropospheric lapse rates, will exist particularly across parts of the south-central Plains to Ozark Plateau, including parts of Kansas/Oklahoma to Arkansas/southern Missouri. As storms diurnally develop/increase, upscale-growing thunderstorm development should occur during the mid to late afternoon and early evening. While weak deep-layer winds and shear are likely to limit the risk for organized severe convection, thermodynamic profiles will be conducive for downbursts and severe-caliber wind gusts with the stronger storms, particularly this afternoon through around sunset. ...Northern Rockies including western/northern Montana... The late-day arrival of weak height falls and approaching mid-level perturbation should influence isolated thunderstorm development late this afternoon, and more so into this evening, across parts of northern Idaho in western and eventually northern Montana. Sufficient moisture/buoyancy near and behind a surface front, along with strengthening flow aloft, will support the possibility of some severe storms, and potentially some clustering/organization to the storms as they progress across western/northern Montana. West-southwesterly mean flow strengthening to 30-40+ kt in the cloud-bearing layer, and a residual deep sub-cloud mixed-layer, will likely be sufficient for downward mixing of momentum to contribute to a few strong to severe wind gusts. ..Guyer/Dean.. 08/19/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Tue Aug 19 2025 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTH-CENTRAL PLAINS AND OZARKS TO OHIO VALLEY AND NORTHERN ROCKIES... ...SUMMARY... Scattered strong to severe thunderstorms capable of damaging winds will be possible across the south-central Great Plains and Ozarks to the Ohio Valley this afternoon and evening. Isolated severe thunderstorms may also occur across parts of the northern Rockies including western and northern Montana. ...South-central Plains and Ozarks to Ohio Valley... Outside of a few areas of lingering early day convection/small-scale outflows, a hot air mass and relatively high moisture content will reside to the south of a synoptic front extending from the south-central Plains to the Midwest/Ohio Valley. Moderate to strong buoyancy with daytime heating, beneath a residual plume of relatively steep lower/mid-tropospheric lapse rates, will exist particularly across parts of the south-central Plains to Ozark Plateau, including parts of Kansas/Oklahoma to Arkansas/southern Missouri. As storms diurnally develop/increase, upscale-growing thunderstorm development should occur during the mid to late afternoon and early evening. While weak deep-layer winds and shear are likely to limit the risk for organized severe convection, thermodynamic profiles will be conducive for downbursts and severe-caliber wind gusts with the stronger storms, particularly this afternoon through around sunset. ...Northern Rockies including western/northern Montana... The late-day arrival of weak height falls and approaching mid-level perturbation should influence isolated thunderstorm development late this afternoon, and more so into this evening, across parts of northern Idaho in western and eventually northern Montana. Sufficient moisture/buoyancy near and behind a surface front, along with strengthening flow aloft, will support the possibility of some severe storms, and potentially some clustering/organization to the storms as they progress across western/northern Montana. West-southwesterly mean flow strengthening to 30-40+ kt in the cloud-bearing layer, and a residual deep sub-cloud mixed-layer, will likely be sufficient for downward mixing of momentum to contribute to a few strong to severe wind gusts. ..Guyer/Dean.. 08/19/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Tue Aug 19 2025 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTH-CENTRAL PLAINS AND OZARKS TO OHIO VALLEY AND NORTHERN ROCKIES... ...SUMMARY... Scattered strong to severe thunderstorms capable of damaging winds will be possible across the south-central Great Plains and Ozarks to the Ohio Valley this afternoon and evening. Isolated severe thunderstorms may also occur across parts of the northern Rockies including western and northern Montana. ...South-central Plains and Ozarks to Ohio Valley... Outside of a few areas of lingering early day convection/small-scale outflows, a hot air mass and relatively high moisture content will reside to the south of a synoptic front extending from the south-central Plains to the Midwest/Ohio Valley. Moderate to strong buoyancy with daytime heating, beneath a residual plume of relatively steep lower/mid-tropospheric lapse rates, will exist particularly across parts of the south-central Plains to Ozark Plateau, including parts of Kansas/Oklahoma to Arkansas/southern Missouri. As storms diurnally develop/increase, upscale-growing thunderstorm development should occur during the mid to late afternoon and early evening. While weak deep-layer winds and shear are likely to limit the risk for organized severe convection, thermodynamic profiles will be conducive for downbursts and severe-caliber wind gusts with the stronger storms, particularly this afternoon through around sunset. ...Northern Rockies including western/northern Montana... The late-day arrival of weak height falls and approaching mid-level perturbation should influence isolated thunderstorm development late this afternoon, and more so into this evening, across parts of northern Idaho in western and eventually northern Montana. Sufficient moisture/buoyancy near and behind a surface front, along with strengthening flow aloft, will support the possibility of some severe storms, and potentially some clustering/organization to the storms as they progress across western/northern Montana. West-southwesterly mean flow strengthening to 30-40+ kt in the cloud-bearing layer, and a residual deep sub-cloud mixed-layer, will likely be sufficient for downward mixing of momentum to contribute to a few strong to severe wind gusts. ..Guyer/Dean.. 08/19/2025 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0349 AM CDT Tue Aug 19 2025 Valid 221200Z - 271200Z ...DISCUSSION... ...Friday/Day 4 to Sunday/Day 6... On Friday, a mid-level shortwave trough and an associated cold front is forecast to move into the upper Mississippi Valley. An axis of moderate instability will likely develop by afternoon ahead of the front from the western Great Lakes southwestward into the mid Missouri Valley. Due to limited large-scale ascent, convective coverage near the instability axis is expected to be very isolated. A marginal risk will be possible with cells that develop close enough to the instability axis. On Saturday, the front is forecast to move through the Great Lakes region, extending southward into the central Plains. Instability will again develop ahead of the front, but convective initiation should remain isolated due to a lack of large-scale ascent. The area with the greatest potential for a marginal severe threat would be over the central Great Lakes ahead of a shortwave trough. The shortwave trough is forecast to amplify over the Great Lakes region on Sunday, as the cold front advances through the lower Great Lakes and Ohio Valley. Instability will increase during the day ahead of the front over the central Appalachians with scattered thunderstorms developing during the afternoon. Deep-layer shear should be strong enough for an isolated wind-damage threat, mainly in areas where instability is stronger. ...Monday/Day 7 and Tuesday/Day 8... A cold front is forecast to advance towards the Eastern Seaboard on Monday. Scattered thunderstorms will be possible Monday afternoon ahead of the front from New England southward into the Mid-Atlantic. Although moderate deep-layer shear is forecast, instability should remain weak, suggesting any severe threat will be marginal. Although uncertainty is substantial at this extended range, the models keep a relatively dry post-frontal airmass over much of the central and eastern U.S on Tuesday. Along the southern periphery of this airmass, isolated thunderstorms will be possible in the southern Plains and Ark-La-Tex Tuesday afternoon. However, weak instability is expected to limit severe threat potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0349 AM CDT Tue Aug 19 2025 Valid 221200Z - 271200Z ...DISCUSSION... ...Friday/Day 4 to Sunday/Day 6... On Friday, a mid-level shortwave trough and an associated cold front is forecast to move into the upper Mississippi Valley. An axis of moderate instability will likely develop by afternoon ahead of the front from the western Great Lakes southwestward into the mid Missouri Valley. Due to limited large-scale ascent, convective coverage near the instability axis is expected to be very isolated. A marginal risk will be possible with cells that develop close enough to the instability axis. On Saturday, the front is forecast to move through the Great Lakes region, extending southward into the central Plains. Instability will again develop ahead of the front, but convective initiation should remain isolated due to a lack of large-scale ascent. The area with the greatest potential for a marginal severe threat would be over the central Great Lakes ahead of a shortwave trough. The shortwave trough is forecast to amplify over the Great Lakes region on Sunday, as the cold front advances through the lower Great Lakes and Ohio Valley. Instability will increase during the day ahead of the front over the central Appalachians with scattered thunderstorms developing during the afternoon. Deep-layer shear should be strong enough for an isolated wind-damage threat, mainly in areas where instability is stronger. ...Monday/Day 7 and Tuesday/Day 8... A cold front is forecast to advance towards the Eastern Seaboard on Monday. Scattered thunderstorms will be possible Monday afternoon ahead of the front from New England southward into the Mid-Atlantic. Although moderate deep-layer shear is forecast, instability should remain weak, suggesting any severe threat will be marginal. Although uncertainty is substantial at this extended range, the models keep a relatively dry post-frontal airmass over much of the central and eastern U.S on Tuesday. Along the southern periphery of this airmass, isolated thunderstorms will be possible in the southern Plains and Ark-La-Tex Tuesday afternoon. However, weak instability is expected to limit severe threat potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0349 AM CDT Tue Aug 19 2025 Valid 221200Z - 271200Z ...DISCUSSION... ...Friday/Day 4 to Sunday/Day 6... On Friday, a mid-level shortwave trough and an associated cold front is forecast to move into the upper Mississippi Valley. An axis of moderate instability will likely develop by afternoon ahead of the front from the western Great Lakes southwestward into the mid Missouri Valley. Due to limited large-scale ascent, convective coverage near the instability axis is expected to be very isolated. A marginal risk will be possible with cells that develop close enough to the instability axis. On Saturday, the front is forecast to move through the Great Lakes region, extending southward into the central Plains. Instability will again develop ahead of the front, but convective initiation should remain isolated due to a lack of large-scale ascent. The area with the greatest potential for a marginal severe threat would be over the central Great Lakes ahead of a shortwave trough. The shortwave trough is forecast to amplify over the Great Lakes region on Sunday, as the cold front advances through the lower Great Lakes and Ohio Valley. Instability will increase during the day ahead of the front over the central Appalachians with scattered thunderstorms developing during the afternoon. Deep-layer shear should be strong enough for an isolated wind-damage threat, mainly in areas where instability is stronger. ...Monday/Day 7 and Tuesday/Day 8... A cold front is forecast to advance towards the Eastern Seaboard on Monday. Scattered thunderstorms will be possible Monday afternoon ahead of the front from New England southward into the Mid-Atlantic. Although moderate deep-layer shear is forecast, instability should remain weak, suggesting any severe threat will be marginal. Although uncertainty is substantial at this extended range, the models keep a relatively dry post-frontal airmass over much of the central and eastern U.S on Tuesday. Along the southern periphery of this airmass, isolated thunderstorms will be possible in the southern Plains and Ark-La-Tex Tuesday afternoon. However, weak instability is expected to limit severe threat potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0349 AM CDT Tue Aug 19 2025 Valid 221200Z - 271200Z ...DISCUSSION... ...Friday/Day 4 to Sunday/Day 6... On Friday, a mid-level shortwave trough and an associated cold front is forecast to move into the upper Mississippi Valley. An axis of moderate instability will likely develop by afternoon ahead of the front from the western Great Lakes southwestward into the mid Missouri Valley. Due to limited large-scale ascent, convective coverage near the instability axis is expected to be very isolated. A marginal risk will be possible with cells that develop close enough to the instability axis. On Saturday, the front is forecast to move through the Great Lakes region, extending southward into the central Plains. Instability will again develop ahead of the front, but convective initiation should remain isolated due to a lack of large-scale ascent. The area with the greatest potential for a marginal severe threat would be over the central Great Lakes ahead of a shortwave trough. The shortwave trough is forecast to amplify over the Great Lakes region on Sunday, as the cold front advances through the lower Great Lakes and Ohio Valley. Instability will increase during the day ahead of the front over the central Appalachians with scattered thunderstorms developing during the afternoon. Deep-layer shear should be strong enough for an isolated wind-damage threat, mainly in areas where instability is stronger. ...Monday/Day 7 and Tuesday/Day 8... A cold front is forecast to advance towards the Eastern Seaboard on Monday. Scattered thunderstorms will be possible Monday afternoon ahead of the front from New England southward into the Mid-Atlantic. Although moderate deep-layer shear is forecast, instability should remain weak, suggesting any severe threat will be marginal. Although uncertainty is substantial at this extended range, the models keep a relatively dry post-frontal airmass over much of the central and eastern U.S on Tuesday. Along the southern periphery of this airmass, isolated thunderstorms will be possible in the southern Plains and Ark-La-Tex Tuesday afternoon. However, weak instability is expected to limit severe threat potential. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Tue Aug 19 2025 Valid 211200Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS... ...SUMMARY... An isolated severe threat is expected to develop over parts of the northern Plains on Thursday, with severe gusts and hail possible. ...Northern Plains... A mid-level shortwave trough is forecast to move eastward across Saskatchewan on Thursday, as a cold front advances southeastward into the northern Plains. Ahead of the front, a north-to-south axis of moderate instability is forecast by afternoon across parts of the eastern South Dakotas. During the late afternoon, scattered thunderstorms are expected to form to the east of the front, from far northwestern Minnesota into the eastern South Dakota. NAM forecast soundings near the instability axis in the late afternoon have MLCAPE peaking in the 2500 to 3500 J/kg range, with 0-6 km shear mostly in the 35 to 45 knot range. This is due to directional shear in the boundary-layer and westerly flow in the mid-levels. This could support a potential for supercells, if modes end up as discrete. Supercells would be capable of hail and isolated severe gusts. There is some uncertainty as to the location of the maximum threat, which will depend on the timing of the front and distribution of low-level moisture and instability. An upgrade in category could be necessary if the models continue to show a more favorable scenario. ..Broyles.. 08/19/2025 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Tue Aug 19 2025 Valid 211200Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS... ...SUMMARY... An isolated severe threat is expected to develop over parts of the northern Plains on Thursday, with severe gusts and hail possible. ...Northern Plains... A mid-level shortwave trough is forecast to move eastward across Saskatchewan on Thursday, as a cold front advances southeastward into the northern Plains. Ahead of the front, a north-to-south axis of moderate instability is forecast by afternoon across parts of the eastern South Dakotas. During the late afternoon, scattered thunderstorms are expected to form to the east of the front, from far northwestern Minnesota into the eastern South Dakota. NAM forecast soundings near the instability axis in the late afternoon have MLCAPE peaking in the 2500 to 3500 J/kg range, with 0-6 km shear mostly in the 35 to 45 knot range. This is due to directional shear in the boundary-layer and westerly flow in the mid-levels. This could support a potential for supercells, if modes end up as discrete. Supercells would be capable of hail and isolated severe gusts. There is some uncertainty as to the location of the maximum threat, which will depend on the timing of the front and distribution of low-level moisture and instability. An upgrade in category could be necessary if the models continue to show a more favorable scenario. ..Broyles.. 08/19/2025 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Tue Aug 19 2025 Valid 211200Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS... ...SUMMARY... An isolated severe threat is expected to develop over parts of the northern Plains on Thursday, with severe gusts and hail possible. ...Northern Plains... A mid-level shortwave trough is forecast to move eastward across Saskatchewan on Thursday, as a cold front advances southeastward into the northern Plains. Ahead of the front, a north-to-south axis of moderate instability is forecast by afternoon across parts of the eastern South Dakotas. During the late afternoon, scattered thunderstorms are expected to form to the east of the front, from far northwestern Minnesota into the eastern South Dakota. NAM forecast soundings near the instability axis in the late afternoon have MLCAPE peaking in the 2500 to 3500 J/kg range, with 0-6 km shear mostly in the 35 to 45 knot range. This is due to directional shear in the boundary-layer and westerly flow in the mid-levels. This could support a potential for supercells, if modes end up as discrete. Supercells would be capable of hail and isolated severe gusts. There is some uncertainty as to the location of the maximum threat, which will depend on the timing of the front and distribution of low-level moisture and instability. An upgrade in category could be necessary if the models continue to show a more favorable scenario. ..Broyles.. 08/19/2025 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Tue Aug 19 2025 Valid 201200Z - 211200Z ...Synopsis... A strong upper ridge is forecast to build over the Southwest as weak troughing continues over parts of the Northwest. A shortwave trough, embedded within the broader northern trough, will move eastward into the northern Rockies Wednesday. Increased southwesterly flow aloft will help monsoon moisture (PWATs 0.6-0.8 inches) advect northward over NV and western UT. A surface cold front associated with the upper trough will stall over the western Great Basin serving as a focus for thunderstorm development through the afternoon. Isolated and likely dry storms are expected over parts of NV and UT. A few storms may possibly continue overnight in eastern Idaho and northwest Wyoming. ...ID... In addition to the isolated risk for thunderstorms, the strong flow aloft and cold front will promote gusty west/southwest winds through portions of the Snake River Plane and northern Great Basin Wednesday. Afternoon gusts of 15-20 mph are possible ahead of the cold front. Very warm temperatures are expected under the ridge with afternoon humidity also expected to be low. With winds and low humidity overlapping with dry fuels, elevated fire-weather conditions are possible. Some dry and breezy conditions may also develop farther south over the Great Basin. However, increasing monsoon moisture along the front and more sporadic surface winds suggest lower confidence for sustained elevated fire-weather conditions. Localized dry and breezy could still occur, especially around any active fires given the very warm and dry conditions. ..Lyons.. 08/19/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more