SPC Aug 13, 2025 1730 UTC Day 2 Convective Outlook

1 week 5 days ago
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1218 PM CDT Wed Aug 13 2025 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN NORTH DAKOTA...NORTHWEST MINNESOTA...AND FAR NORTHEAST SOUTH DAKOTA... ...SUMMARY... Severe storms producing hail and wind are possible mainly from eastern North Dakota into northwest Minnesota Thursday afternoon and evening. Isolated severe storms may occur across parts of South Dakota into western Nebraska. ...Synopsis... A mid-level shortwave trough and ongoing convection should be located somewhere near eastern South Dakota Thursday morning and weaken as it moves toward Lake Superior by 12Z Friday. Stronger mid-level flow along the northern periphery of a broad ridge centered over the Plains will shift east across the Canadian Prairies and northern Plains during the day on Thursday. A lee cyclone will be present across Saskatchewan/Manitoba at the beginning of the period and move east through the day. A surface trough/dryline will extend south from this surface low into the northern/central Plains. A cold front will strengthen through the period and eventually shift south across eastern Montana/North Dakota. ...Northern Plains... Thunderstorms associated with a passing mid-level shortwave trough will likely be across eastern South Dakota at the start of the period and advance east through the day. In the wake of this wave, subsidence should suppress convection for most of the day. By evening, strong heating should result in an uncapped environment amid strong instability. Upper forcing appears quite nebulous amid neutral to slightly rising heights. Therefore, storm coverage remains questionable. The best chance for scattered storm coverage will be across northeast North Dakota and far northwest Minnesota where scattered supercells capable of large hail (some very large) and severe wind gusts are expected. Farther south, storm coverage is less likely. However, given the strong heating along the dryline/surface trough, at least isolated storm development should occur and the environment would support severe storms. ...Central South Dakota into northwest Nebraska... Strong heating and very strong instability is expected to develop along the trough from central South Dakota into northwest Nebraska. Weak forcing should result in isolated storm coverage along this boundary during the late afternoon/evening. Shear will not be as strong this far south, but high-based storms may still be capable of isolated large hail and severe wind gusts. ..Bentley.. 08/13/2025 Read more

SPC Aug 13, 2025 1730 UTC Day 2 Convective Outlook

1 week 5 days ago
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1218 PM CDT Wed Aug 13 2025 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN NORTH DAKOTA...NORTHWEST MINNESOTA...AND FAR NORTHEAST SOUTH DAKOTA... ...SUMMARY... Severe storms producing hail and wind are possible mainly from eastern North Dakota into northwest Minnesota Thursday afternoon and evening. Isolated severe storms may occur across parts of South Dakota into western Nebraska. ...Synopsis... A mid-level shortwave trough and ongoing convection should be located somewhere near eastern South Dakota Thursday morning and weaken as it moves toward Lake Superior by 12Z Friday. Stronger mid-level flow along the northern periphery of a broad ridge centered over the Plains will shift east across the Canadian Prairies and northern Plains during the day on Thursday. A lee cyclone will be present across Saskatchewan/Manitoba at the beginning of the period and move east through the day. A surface trough/dryline will extend south from this surface low into the northern/central Plains. A cold front will strengthen through the period and eventually shift south across eastern Montana/North Dakota. ...Northern Plains... Thunderstorms associated with a passing mid-level shortwave trough will likely be across eastern South Dakota at the start of the period and advance east through the day. In the wake of this wave, subsidence should suppress convection for most of the day. By evening, strong heating should result in an uncapped environment amid strong instability. Upper forcing appears quite nebulous amid neutral to slightly rising heights. Therefore, storm coverage remains questionable. The best chance for scattered storm coverage will be across northeast North Dakota and far northwest Minnesota where scattered supercells capable of large hail (some very large) and severe wind gusts are expected. Farther south, storm coverage is less likely. However, given the strong heating along the dryline/surface trough, at least isolated storm development should occur and the environment would support severe storms. ...Central South Dakota into northwest Nebraska... Strong heating and very strong instability is expected to develop along the trough from central South Dakota into northwest Nebraska. Weak forcing should result in isolated storm coverage along this boundary during the late afternoon/evening. Shear will not be as strong this far south, but high-based storms may still be capable of isolated large hail and severe wind gusts. ..Bentley.. 08/13/2025 Read more

SPC Aug 13, 2025 1730 UTC Day 2 Convective Outlook

1 week 5 days ago
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1218 PM CDT Wed Aug 13 2025 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN NORTH DAKOTA...NORTHWEST MINNESOTA...AND FAR NORTHEAST SOUTH DAKOTA... ...SUMMARY... Severe storms producing hail and wind are possible mainly from eastern North Dakota into northwest Minnesota Thursday afternoon and evening. Isolated severe storms may occur across parts of South Dakota into western Nebraska. ...Synopsis... A mid-level shortwave trough and ongoing convection should be located somewhere near eastern South Dakota Thursday morning and weaken as it moves toward Lake Superior by 12Z Friday. Stronger mid-level flow along the northern periphery of a broad ridge centered over the Plains will shift east across the Canadian Prairies and northern Plains during the day on Thursday. A lee cyclone will be present across Saskatchewan/Manitoba at the beginning of the period and move east through the day. A surface trough/dryline will extend south from this surface low into the northern/central Plains. A cold front will strengthen through the period and eventually shift south across eastern Montana/North Dakota. ...Northern Plains... Thunderstorms associated with a passing mid-level shortwave trough will likely be across eastern South Dakota at the start of the period and advance east through the day. In the wake of this wave, subsidence should suppress convection for most of the day. By evening, strong heating should result in an uncapped environment amid strong instability. Upper forcing appears quite nebulous amid neutral to slightly rising heights. Therefore, storm coverage remains questionable. The best chance for scattered storm coverage will be across northeast North Dakota and far northwest Minnesota where scattered supercells capable of large hail (some very large) and severe wind gusts are expected. Farther south, storm coverage is less likely. However, given the strong heating along the dryline/surface trough, at least isolated storm development should occur and the environment would support severe storms. ...Central South Dakota into northwest Nebraska... Strong heating and very strong instability is expected to develop along the trough from central South Dakota into northwest Nebraska. Weak forcing should result in isolated storm coverage along this boundary during the late afternoon/evening. Shear will not be as strong this far south, but high-based storms may still be capable of isolated large hail and severe wind gusts. ..Bentley.. 08/13/2025 Read more

SPC Aug 13, 2025 1730 UTC Day 2 Convective Outlook

1 week 5 days ago
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1218 PM CDT Wed Aug 13 2025 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN NORTH DAKOTA...NORTHWEST MINNESOTA...AND FAR NORTHEAST SOUTH DAKOTA... ...SUMMARY... Severe storms producing hail and wind are possible mainly from eastern North Dakota into northwest Minnesota Thursday afternoon and evening. Isolated severe storms may occur across parts of South Dakota into western Nebraska. ...Synopsis... A mid-level shortwave trough and ongoing convection should be located somewhere near eastern South Dakota Thursday morning and weaken as it moves toward Lake Superior by 12Z Friday. Stronger mid-level flow along the northern periphery of a broad ridge centered over the Plains will shift east across the Canadian Prairies and northern Plains during the day on Thursday. A lee cyclone will be present across Saskatchewan/Manitoba at the beginning of the period and move east through the day. A surface trough/dryline will extend south from this surface low into the northern/central Plains. A cold front will strengthen through the period and eventually shift south across eastern Montana/North Dakota. ...Northern Plains... Thunderstorms associated with a passing mid-level shortwave trough will likely be across eastern South Dakota at the start of the period and advance east through the day. In the wake of this wave, subsidence should suppress convection for most of the day. By evening, strong heating should result in an uncapped environment amid strong instability. Upper forcing appears quite nebulous amid neutral to slightly rising heights. Therefore, storm coverage remains questionable. The best chance for scattered storm coverage will be across northeast North Dakota and far northwest Minnesota where scattered supercells capable of large hail (some very large) and severe wind gusts are expected. Farther south, storm coverage is less likely. However, given the strong heating along the dryline/surface trough, at least isolated storm development should occur and the environment would support severe storms. ...Central South Dakota into northwest Nebraska... Strong heating and very strong instability is expected to develop along the trough from central South Dakota into northwest Nebraska. Weak forcing should result in isolated storm coverage along this boundary during the late afternoon/evening. Shear will not be as strong this far south, but high-based storms may still be capable of isolated large hail and severe wind gusts. ..Bentley.. 08/13/2025 Read more

SPC Day 1 Fire Weather Outlook

1 week 5 days ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook CORR 2 NWS Storm Prediction Center Norman OK 1153 AM CDT Wed Aug 13 2025 Valid 131700Z - 141200Z CORRECTED FOR INCORRECT HEADLINE AND MISSING AREA ...CRITICAL FIRE WEATHER AREA FOR EASTERN IDAHO... Adjustments were made to extend the Elevated across central Idaho. While winds may not meet temporal criteria, new lightning fires were reported overnight across this region with relative humidity expected to drop to 15-20%. Minor adjustments were made to the isolated dry thunderstorm chances across Idaho and northern Nevada in alignment with trends in recent high-res guidance. See previous discussion below for more information. ..Thornton.. 08/13/2025 .PREV DISCUSSION... /ISSUED 0133 AM CDT Wed Aug 13 2025/ ...Synopsis... Widespread elevated to critical fire weather conditions are expected today across a large swath of the Intermountain West. An upper wave currently approaching the Pacific Northwest is expected to progress quickly to the High Plains over the next 24 hours. As this occurs, ascent ahead of the wave will induce surface pressure falls across the northern Great Basin and northern Rockies. The low-level mass response should promote widespread sustained winds in the 15-25 mph range from the lee of the Cascades and Sierra Nevada into portions of WY. Deep mixing should promote frequent gusts between 25-30 mph. Transient swaths of 20+ mph winds will be possible across much of the region, but confidence in sustained critical wind speeds remains highest through the Snake River Plain in southern/eastern ID where flow will be orographically enhanced. 06 UTC surface observations across the Great Basin show very dry conditions already in place, and diurnal heating of this dry air mass will support widespread RH reductions into the 5-15% range. Recent fuel guidance shows widespread ERCs above the 90th percentile across much of the region, which should support the fire weather threat. ...Dry Thunderstorms... A few early-morning thunderstorms are noted in GOES GLM data between 04-05 UTC across portions of NV (likely associated with ascent ahead of a weak leading upper perturbation), though more substantial thunderstorm activity is expected later this afternoon and evening across the Great Basin. 00z soundings, water-vapor imagery, and the recent convection all confirm that a plume of mid-level moisture is in place ahead of the primary upper trough. As ascent and diurnal heating increase through the afternoon, a swath of isolated to scattered thunderstorms will likely develop from far eastern CA to eastern ID/western WY. Very deep and well-mixed boundary layers, coupled with storm motions near 20 knots, will promote mainly dry thunderstorms. With receptive fuels in place, this convection will pose a threat for new fire starts. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

1 week 5 days ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook CORR 2 NWS Storm Prediction Center Norman OK 1153 AM CDT Wed Aug 13 2025 Valid 131700Z - 141200Z CORRECTED FOR INCORRECT HEADLINE AND MISSING AREA ...CRITICAL FIRE WEATHER AREA FOR EASTERN IDAHO... Adjustments were made to extend the Elevated across central Idaho. While winds may not meet temporal criteria, new lightning fires were reported overnight across this region with relative humidity expected to drop to 15-20%. Minor adjustments were made to the isolated dry thunderstorm chances across Idaho and northern Nevada in alignment with trends in recent high-res guidance. See previous discussion below for more information. ..Thornton.. 08/13/2025 .PREV DISCUSSION... /ISSUED 0133 AM CDT Wed Aug 13 2025/ ...Synopsis... Widespread elevated to critical fire weather conditions are expected today across a large swath of the Intermountain West. An upper wave currently approaching the Pacific Northwest is expected to progress quickly to the High Plains over the next 24 hours. As this occurs, ascent ahead of the wave will induce surface pressure falls across the northern Great Basin and northern Rockies. The low-level mass response should promote widespread sustained winds in the 15-25 mph range from the lee of the Cascades and Sierra Nevada into portions of WY. Deep mixing should promote frequent gusts between 25-30 mph. Transient swaths of 20+ mph winds will be possible across much of the region, but confidence in sustained critical wind speeds remains highest through the Snake River Plain in southern/eastern ID where flow will be orographically enhanced. 06 UTC surface observations across the Great Basin show very dry conditions already in place, and diurnal heating of this dry air mass will support widespread RH reductions into the 5-15% range. Recent fuel guidance shows widespread ERCs above the 90th percentile across much of the region, which should support the fire weather threat. ...Dry Thunderstorms... A few early-morning thunderstorms are noted in GOES GLM data between 04-05 UTC across portions of NV (likely associated with ascent ahead of a weak leading upper perturbation), though more substantial thunderstorm activity is expected later this afternoon and evening across the Great Basin. 00z soundings, water-vapor imagery, and the recent convection all confirm that a plume of mid-level moisture is in place ahead of the primary upper trough. As ascent and diurnal heating increase through the afternoon, a swath of isolated to scattered thunderstorms will likely develop from far eastern CA to eastern ID/western WY. Very deep and well-mixed boundary layers, coupled with storm motions near 20 knots, will promote mainly dry thunderstorms. With receptive fuels in place, this convection will pose a threat for new fire starts. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

1 week 5 days ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook CORR 2 NWS Storm Prediction Center Norman OK 1153 AM CDT Wed Aug 13 2025 Valid 131700Z - 141200Z CORRECTED FOR INCORRECT HEADLINE AND MISSING AREA ...CRITICAL FIRE WEATHER AREA FOR EASTERN IDAHO... Adjustments were made to extend the Elevated across central Idaho. While winds may not meet temporal criteria, new lightning fires were reported overnight across this region with relative humidity expected to drop to 15-20%. Minor adjustments were made to the isolated dry thunderstorm chances across Idaho and northern Nevada in alignment with trends in recent high-res guidance. See previous discussion below for more information. ..Thornton.. 08/13/2025 .PREV DISCUSSION... /ISSUED 0133 AM CDT Wed Aug 13 2025/ ...Synopsis... Widespread elevated to critical fire weather conditions are expected today across a large swath of the Intermountain West. An upper wave currently approaching the Pacific Northwest is expected to progress quickly to the High Plains over the next 24 hours. As this occurs, ascent ahead of the wave will induce surface pressure falls across the northern Great Basin and northern Rockies. The low-level mass response should promote widespread sustained winds in the 15-25 mph range from the lee of the Cascades and Sierra Nevada into portions of WY. Deep mixing should promote frequent gusts between 25-30 mph. Transient swaths of 20+ mph winds will be possible across much of the region, but confidence in sustained critical wind speeds remains highest through the Snake River Plain in southern/eastern ID where flow will be orographically enhanced. 06 UTC surface observations across the Great Basin show very dry conditions already in place, and diurnal heating of this dry air mass will support widespread RH reductions into the 5-15% range. Recent fuel guidance shows widespread ERCs above the 90th percentile across much of the region, which should support the fire weather threat. ...Dry Thunderstorms... A few early-morning thunderstorms are noted in GOES GLM data between 04-05 UTC across portions of NV (likely associated with ascent ahead of a weak leading upper perturbation), though more substantial thunderstorm activity is expected later this afternoon and evening across the Great Basin. 00z soundings, water-vapor imagery, and the recent convection all confirm that a plume of mid-level moisture is in place ahead of the primary upper trough. As ascent and diurnal heating increase through the afternoon, a swath of isolated to scattered thunderstorms will likely develop from far eastern CA to eastern ID/western WY. Very deep and well-mixed boundary layers, coupled with storm motions near 20 knots, will promote mainly dry thunderstorms. With receptive fuels in place, this convection will pose a threat for new fire starts. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

1 week 5 days ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook CORR 2 NWS Storm Prediction Center Norman OK 1153 AM CDT Wed Aug 13 2025 Valid 131700Z - 141200Z CORRECTED FOR INCORRECT HEADLINE AND MISSING AREA ...CRITICAL FIRE WEATHER AREA FOR EASTERN IDAHO... Adjustments were made to extend the Elevated across central Idaho. While winds may not meet temporal criteria, new lightning fires were reported overnight across this region with relative humidity expected to drop to 15-20%. Minor adjustments were made to the isolated dry thunderstorm chances across Idaho and northern Nevada in alignment with trends in recent high-res guidance. See previous discussion below for more information. ..Thornton.. 08/13/2025 .PREV DISCUSSION... /ISSUED 0133 AM CDT Wed Aug 13 2025/ ...Synopsis... Widespread elevated to critical fire weather conditions are expected today across a large swath of the Intermountain West. An upper wave currently approaching the Pacific Northwest is expected to progress quickly to the High Plains over the next 24 hours. As this occurs, ascent ahead of the wave will induce surface pressure falls across the northern Great Basin and northern Rockies. The low-level mass response should promote widespread sustained winds in the 15-25 mph range from the lee of the Cascades and Sierra Nevada into portions of WY. Deep mixing should promote frequent gusts between 25-30 mph. Transient swaths of 20+ mph winds will be possible across much of the region, but confidence in sustained critical wind speeds remains highest through the Snake River Plain in southern/eastern ID where flow will be orographically enhanced. 06 UTC surface observations across the Great Basin show very dry conditions already in place, and diurnal heating of this dry air mass will support widespread RH reductions into the 5-15% range. Recent fuel guidance shows widespread ERCs above the 90th percentile across much of the region, which should support the fire weather threat. ...Dry Thunderstorms... A few early-morning thunderstorms are noted in GOES GLM data between 04-05 UTC across portions of NV (likely associated with ascent ahead of a weak leading upper perturbation), though more substantial thunderstorm activity is expected later this afternoon and evening across the Great Basin. 00z soundings, water-vapor imagery, and the recent convection all confirm that a plume of mid-level moisture is in place ahead of the primary upper trough. As ascent and diurnal heating increase through the afternoon, a swath of isolated to scattered thunderstorms will likely develop from far eastern CA to eastern ID/western WY. Very deep and well-mixed boundary layers, coupled with storm motions near 20 knots, will promote mainly dry thunderstorms. With receptive fuels in place, this convection will pose a threat for new fire starts. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

1 week 5 days ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook CORR 2 NWS Storm Prediction Center Norman OK 1153 AM CDT Wed Aug 13 2025 Valid 131700Z - 141200Z CORRECTED FOR INCORRECT HEADLINE AND MISSING AREA ...CRITICAL FIRE WEATHER AREA FOR EASTERN IDAHO... Adjustments were made to extend the Elevated across central Idaho. While winds may not meet temporal criteria, new lightning fires were reported overnight across this region with relative humidity expected to drop to 15-20%. Minor adjustments were made to the isolated dry thunderstorm chances across Idaho and northern Nevada in alignment with trends in recent high-res guidance. See previous discussion below for more information. ..Thornton.. 08/13/2025 .PREV DISCUSSION... /ISSUED 0133 AM CDT Wed Aug 13 2025/ ...Synopsis... Widespread elevated to critical fire weather conditions are expected today across a large swath of the Intermountain West. An upper wave currently approaching the Pacific Northwest is expected to progress quickly to the High Plains over the next 24 hours. As this occurs, ascent ahead of the wave will induce surface pressure falls across the northern Great Basin and northern Rockies. The low-level mass response should promote widespread sustained winds in the 15-25 mph range from the lee of the Cascades and Sierra Nevada into portions of WY. Deep mixing should promote frequent gusts between 25-30 mph. Transient swaths of 20+ mph winds will be possible across much of the region, but confidence in sustained critical wind speeds remains highest through the Snake River Plain in southern/eastern ID where flow will be orographically enhanced. 06 UTC surface observations across the Great Basin show very dry conditions already in place, and diurnal heating of this dry air mass will support widespread RH reductions into the 5-15% range. Recent fuel guidance shows widespread ERCs above the 90th percentile across much of the region, which should support the fire weather threat. ...Dry Thunderstorms... A few early-morning thunderstorms are noted in GOES GLM data between 04-05 UTC across portions of NV (likely associated with ascent ahead of a weak leading upper perturbation), though more substantial thunderstorm activity is expected later this afternoon and evening across the Great Basin. 00z soundings, water-vapor imagery, and the recent convection all confirm that a plume of mid-level moisture is in place ahead of the primary upper trough. As ascent and diurnal heating increase through the afternoon, a swath of isolated to scattered thunderstorms will likely develop from far eastern CA to eastern ID/western WY. Very deep and well-mixed boundary layers, coupled with storm motions near 20 knots, will promote mainly dry thunderstorms. With receptive fuels in place, this convection will pose a threat for new fire starts. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

1 week 5 days ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook CORR 2 NWS Storm Prediction Center Norman OK 1153 AM CDT Wed Aug 13 2025 Valid 131700Z - 141200Z CORRECTED FOR INCORRECT HEADLINE AND MISSING AREA ...CRITICAL FIRE WEATHER AREA FOR EASTERN IDAHO... Adjustments were made to extend the Elevated across central Idaho. While winds may not meet temporal criteria, new lightning fires were reported overnight across this region with relative humidity expected to drop to 15-20%. Minor adjustments were made to the isolated dry thunderstorm chances across Idaho and northern Nevada in alignment with trends in recent high-res guidance. See previous discussion below for more information. ..Thornton.. 08/13/2025 .PREV DISCUSSION... /ISSUED 0133 AM CDT Wed Aug 13 2025/ ...Synopsis... Widespread elevated to critical fire weather conditions are expected today across a large swath of the Intermountain West. An upper wave currently approaching the Pacific Northwest is expected to progress quickly to the High Plains over the next 24 hours. As this occurs, ascent ahead of the wave will induce surface pressure falls across the northern Great Basin and northern Rockies. The low-level mass response should promote widespread sustained winds in the 15-25 mph range from the lee of the Cascades and Sierra Nevada into portions of WY. Deep mixing should promote frequent gusts between 25-30 mph. Transient swaths of 20+ mph winds will be possible across much of the region, but confidence in sustained critical wind speeds remains highest through the Snake River Plain in southern/eastern ID where flow will be orographically enhanced. 06 UTC surface observations across the Great Basin show very dry conditions already in place, and diurnal heating of this dry air mass will support widespread RH reductions into the 5-15% range. Recent fuel guidance shows widespread ERCs above the 90th percentile across much of the region, which should support the fire weather threat. ...Dry Thunderstorms... A few early-morning thunderstorms are noted in GOES GLM data between 04-05 UTC across portions of NV (likely associated with ascent ahead of a weak leading upper perturbation), though more substantial thunderstorm activity is expected later this afternoon and evening across the Great Basin. 00z soundings, water-vapor imagery, and the recent convection all confirm that a plume of mid-level moisture is in place ahead of the primary upper trough. As ascent and diurnal heating increase through the afternoon, a swath of isolated to scattered thunderstorms will likely develop from far eastern CA to eastern ID/western WY. Very deep and well-mixed boundary layers, coupled with storm motions near 20 knots, will promote mainly dry thunderstorms. With receptive fuels in place, this convection will pose a threat for new fire starts. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

1 week 5 days ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook CORR 2 NWS Storm Prediction Center Norman OK 1153 AM CDT Wed Aug 13 2025 Valid 131700Z - 141200Z CORRECTED FOR INCORRECT HEADLINE AND MISSING AREA ...CRITICAL FIRE WEATHER AREA FOR EASTERN IDAHO... Adjustments were made to extend the Elevated across central Idaho. While winds may not meet temporal criteria, new lightning fires were reported overnight across this region with relative humidity expected to drop to 15-20%. Minor adjustments were made to the isolated dry thunderstorm chances across Idaho and northern Nevada in alignment with trends in recent high-res guidance. See previous discussion below for more information. ..Thornton.. 08/13/2025 .PREV DISCUSSION... /ISSUED 0133 AM CDT Wed Aug 13 2025/ ...Synopsis... Widespread elevated to critical fire weather conditions are expected today across a large swath of the Intermountain West. An upper wave currently approaching the Pacific Northwest is expected to progress quickly to the High Plains over the next 24 hours. As this occurs, ascent ahead of the wave will induce surface pressure falls across the northern Great Basin and northern Rockies. The low-level mass response should promote widespread sustained winds in the 15-25 mph range from the lee of the Cascades and Sierra Nevada into portions of WY. Deep mixing should promote frequent gusts between 25-30 mph. Transient swaths of 20+ mph winds will be possible across much of the region, but confidence in sustained critical wind speeds remains highest through the Snake River Plain in southern/eastern ID where flow will be orographically enhanced. 06 UTC surface observations across the Great Basin show very dry conditions already in place, and diurnal heating of this dry air mass will support widespread RH reductions into the 5-15% range. Recent fuel guidance shows widespread ERCs above the 90th percentile across much of the region, which should support the fire weather threat. ...Dry Thunderstorms... A few early-morning thunderstorms are noted in GOES GLM data between 04-05 UTC across portions of NV (likely associated with ascent ahead of a weak leading upper perturbation), though more substantial thunderstorm activity is expected later this afternoon and evening across the Great Basin. 00z soundings, water-vapor imagery, and the recent convection all confirm that a plume of mid-level moisture is in place ahead of the primary upper trough. As ascent and diurnal heating increase through the afternoon, a swath of isolated to scattered thunderstorms will likely develop from far eastern CA to eastern ID/western WY. Very deep and well-mixed boundary layers, coupled with storm motions near 20 knots, will promote mainly dry thunderstorms. With receptive fuels in place, this convection will pose a threat for new fire starts. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

1 week 5 days ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook CORR 2 NWS Storm Prediction Center Norman OK 1153 AM CDT Wed Aug 13 2025 Valid 131700Z - 141200Z CORRECTED FOR INCORRECT HEADLINE AND MISSING AREA ...CRITICAL FIRE WEATHER AREA FOR EASTERN IDAHO... Adjustments were made to extend the Elevated across central Idaho. While winds may not meet temporal criteria, new lightning fires were reported overnight across this region with relative humidity expected to drop to 15-20%. Minor adjustments were made to the isolated dry thunderstorm chances across Idaho and northern Nevada in alignment with trends in recent high-res guidance. See previous discussion below for more information. ..Thornton.. 08/13/2025 .PREV DISCUSSION... /ISSUED 0133 AM CDT Wed Aug 13 2025/ ...Synopsis... Widespread elevated to critical fire weather conditions are expected today across a large swath of the Intermountain West. An upper wave currently approaching the Pacific Northwest is expected to progress quickly to the High Plains over the next 24 hours. As this occurs, ascent ahead of the wave will induce surface pressure falls across the northern Great Basin and northern Rockies. The low-level mass response should promote widespread sustained winds in the 15-25 mph range from the lee of the Cascades and Sierra Nevada into portions of WY. Deep mixing should promote frequent gusts between 25-30 mph. Transient swaths of 20+ mph winds will be possible across much of the region, but confidence in sustained critical wind speeds remains highest through the Snake River Plain in southern/eastern ID where flow will be orographically enhanced. 06 UTC surface observations across the Great Basin show very dry conditions already in place, and diurnal heating of this dry air mass will support widespread RH reductions into the 5-15% range. Recent fuel guidance shows widespread ERCs above the 90th percentile across much of the region, which should support the fire weather threat. ...Dry Thunderstorms... A few early-morning thunderstorms are noted in GOES GLM data between 04-05 UTC across portions of NV (likely associated with ascent ahead of a weak leading upper perturbation), though more substantial thunderstorm activity is expected later this afternoon and evening across the Great Basin. 00z soundings, water-vapor imagery, and the recent convection all confirm that a plume of mid-level moisture is in place ahead of the primary upper trough. As ascent and diurnal heating increase through the afternoon, a swath of isolated to scattered thunderstorms will likely develop from far eastern CA to eastern ID/western WY. Very deep and well-mixed boundary layers, coupled with storm motions near 20 knots, will promote mainly dry thunderstorms. With receptive fuels in place, this convection will pose a threat for new fire starts. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

1 week 5 days ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook CORR 2 NWS Storm Prediction Center Norman OK 1153 AM CDT Wed Aug 13 2025 Valid 131700Z - 141200Z CORRECTED FOR INCORRECT HEADLINE AND MISSING AREA ...CRITICAL FIRE WEATHER AREA FOR EASTERN IDAHO... Adjustments were made to extend the Elevated across central Idaho. While winds may not meet temporal criteria, new lightning fires were reported overnight across this region with relative humidity expected to drop to 15-20%. Minor adjustments were made to the isolated dry thunderstorm chances across Idaho and northern Nevada in alignment with trends in recent high-res guidance. See previous discussion below for more information. ..Thornton.. 08/13/2025 .PREV DISCUSSION... /ISSUED 0133 AM CDT Wed Aug 13 2025/ ...Synopsis... Widespread elevated to critical fire weather conditions are expected today across a large swath of the Intermountain West. An upper wave currently approaching the Pacific Northwest is expected to progress quickly to the High Plains over the next 24 hours. As this occurs, ascent ahead of the wave will induce surface pressure falls across the northern Great Basin and northern Rockies. The low-level mass response should promote widespread sustained winds in the 15-25 mph range from the lee of the Cascades and Sierra Nevada into portions of WY. Deep mixing should promote frequent gusts between 25-30 mph. Transient swaths of 20+ mph winds will be possible across much of the region, but confidence in sustained critical wind speeds remains highest through the Snake River Plain in southern/eastern ID where flow will be orographically enhanced. 06 UTC surface observations across the Great Basin show very dry conditions already in place, and diurnal heating of this dry air mass will support widespread RH reductions into the 5-15% range. Recent fuel guidance shows widespread ERCs above the 90th percentile across much of the region, which should support the fire weather threat. ...Dry Thunderstorms... A few early-morning thunderstorms are noted in GOES GLM data between 04-05 UTC across portions of NV (likely associated with ascent ahead of a weak leading upper perturbation), though more substantial thunderstorm activity is expected later this afternoon and evening across the Great Basin. 00z soundings, water-vapor imagery, and the recent convection all confirm that a plume of mid-level moisture is in place ahead of the primary upper trough. As ascent and diurnal heating increase through the afternoon, a swath of isolated to scattered thunderstorms will likely develop from far eastern CA to eastern ID/western WY. Very deep and well-mixed boundary layers, coupled with storm motions near 20 knots, will promote mainly dry thunderstorms. With receptive fuels in place, this convection will pose a threat for new fire starts. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

1 week 5 days ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook CORR 2 NWS Storm Prediction Center Norman OK 1153 AM CDT Wed Aug 13 2025 Valid 131700Z - 141200Z CORRECTED FOR INCORRECT HEADLINE AND MISSING AREA ...CRITICAL FIRE WEATHER AREA FOR EASTERN IDAHO... Adjustments were made to extend the Elevated across central Idaho. While winds may not meet temporal criteria, new lightning fires were reported overnight across this region with relative humidity expected to drop to 15-20%. Minor adjustments were made to the isolated dry thunderstorm chances across Idaho and northern Nevada in alignment with trends in recent high-res guidance. See previous discussion below for more information. ..Thornton.. 08/13/2025 .PREV DISCUSSION... /ISSUED 0133 AM CDT Wed Aug 13 2025/ ...Synopsis... Widespread elevated to critical fire weather conditions are expected today across a large swath of the Intermountain West. An upper wave currently approaching the Pacific Northwest is expected to progress quickly to the High Plains over the next 24 hours. As this occurs, ascent ahead of the wave will induce surface pressure falls across the northern Great Basin and northern Rockies. The low-level mass response should promote widespread sustained winds in the 15-25 mph range from the lee of the Cascades and Sierra Nevada into portions of WY. Deep mixing should promote frequent gusts between 25-30 mph. Transient swaths of 20+ mph winds will be possible across much of the region, but confidence in sustained critical wind speeds remains highest through the Snake River Plain in southern/eastern ID where flow will be orographically enhanced. 06 UTC surface observations across the Great Basin show very dry conditions already in place, and diurnal heating of this dry air mass will support widespread RH reductions into the 5-15% range. Recent fuel guidance shows widespread ERCs above the 90th percentile across much of the region, which should support the fire weather threat. ...Dry Thunderstorms... A few early-morning thunderstorms are noted in GOES GLM data between 04-05 UTC across portions of NV (likely associated with ascent ahead of a weak leading upper perturbation), though more substantial thunderstorm activity is expected later this afternoon and evening across the Great Basin. 00z soundings, water-vapor imagery, and the recent convection all confirm that a plume of mid-level moisture is in place ahead of the primary upper trough. As ascent and diurnal heating increase through the afternoon, a swath of isolated to scattered thunderstorms will likely develop from far eastern CA to eastern ID/western WY. Very deep and well-mixed boundary layers, coupled with storm motions near 20 knots, will promote mainly dry thunderstorms. With receptive fuels in place, this convection will pose a threat for new fire starts. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Aug 13, 2025 1630 UTC Day 1 Convective Outlook

1 week 5 days ago
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook RESENT 1 NWS Storm Prediction Center Norman OK 1146 AM CDT Wed Aug 13 2025 Valid 131630Z - 141200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTH DAKOTA AND NORTH-CENTRAL NEBRASKA... ...SUMMARY... Scattered severe wind gusts and isolated large hail may occur across parts of the northern/central Plains this evening and overnight. Thunderstorms across portions of the Northeast and Mid-Atlantic may produce occasional damaging winds this afternoon. ...Northern/Central Plains... Recent satellite imagery shows a low-amplitude shortwave trough moving through southwest MT. This shortwave is forecast to continue eastward along the MT/WY border vicinity today, before continuing through the Dakotas/NE tonight. The airmass preceding this shortwave across southeast MT/northeast WY is relatively dry, with dewpoints currently in the low to mid 50s. Greater low-level moisture is in place farther east, with dewpoints increasing into the low 60s across south-central SD and north-central NE. Southerly low-level flow is anticipated throughout the day, helping to offset some of the mixing expected amid strong diurnal heating. This should result in a modestly moist, deeply mixed airmass across the southeast MT/northeast WY/western SD vicinity by the late afternoon when the forcing for ascent attendant to the approaching shortwave reaches the region. This modest large-scale ascent show work in tandem with robust daytime heating and localized orographic effects near the Black Hills to initiate thunderstorms. High-based storms are anticipated initially, which could result in strong outflow with any more mature storms. A few instances of hail as possible as well. Greater low-level moisture and buoyancy will be in place farther east (i.e. into more of western/central SD), which will combine with persistent large-scale forcing for ascent and a strengthening low-level jet to support upscale growth into a convective line. This should foster a continued threat for damaging gusts into south-central SD and far north-central NE this evening. The threat should diminish with eastern extent given nocturnal stabilization and increasing convective inhibition. ...Northeast/Mid-Atlantic... Dewpoints currently range from the low 70s over the northern Mid-Atlantic into the low 60s across northern NH/VT. Thunderstorms are already developing within this moist and moderately buoyant airmass as large-scale ascent attendant to upper troughing advancing eastward over Ontario/Quebec glances the region. Deep-layer vertical shear is expected to remain weak throughout the day (i.e. effective bulk shear generally less than 25 kt), which should limit overall storm strength and organization. Even so, steep low-level lapse rates could aid in the development of occasionally damaging gusts with any of the deeper convective cores. Greater buoyancy could result in a relatively higher probability for damaging gusts from the NY Hudson Valley into eastern PA/NJ. Refer to recently issued MCD #1938 for additional information. ..Mosier/Squitieri.. 08/13/2025 Read more

SPC Aug 13, 2025 1630 UTC Day 1 Convective Outlook

1 week 5 days ago
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook RESENT 1 NWS Storm Prediction Center Norman OK 1146 AM CDT Wed Aug 13 2025 Valid 131630Z - 141200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTH DAKOTA AND NORTH-CENTRAL NEBRASKA... ...SUMMARY... Scattered severe wind gusts and isolated large hail may occur across parts of the northern/central Plains this evening and overnight. Thunderstorms across portions of the Northeast and Mid-Atlantic may produce occasional damaging winds this afternoon. ...Northern/Central Plains... Recent satellite imagery shows a low-amplitude shortwave trough moving through southwest MT. This shortwave is forecast to continue eastward along the MT/WY border vicinity today, before continuing through the Dakotas/NE tonight. The airmass preceding this shortwave across southeast MT/northeast WY is relatively dry, with dewpoints currently in the low to mid 50s. Greater low-level moisture is in place farther east, with dewpoints increasing into the low 60s across south-central SD and north-central NE. Southerly low-level flow is anticipated throughout the day, helping to offset some of the mixing expected amid strong diurnal heating. This should result in a modestly moist, deeply mixed airmass across the southeast MT/northeast WY/western SD vicinity by the late afternoon when the forcing for ascent attendant to the approaching shortwave reaches the region. This modest large-scale ascent show work in tandem with robust daytime heating and localized orographic effects near the Black Hills to initiate thunderstorms. High-based storms are anticipated initially, which could result in strong outflow with any more mature storms. A few instances of hail as possible as well. Greater low-level moisture and buoyancy will be in place farther east (i.e. into more of western/central SD), which will combine with persistent large-scale forcing for ascent and a strengthening low-level jet to support upscale growth into a convective line. This should foster a continued threat for damaging gusts into south-central SD and far north-central NE this evening. The threat should diminish with eastern extent given nocturnal stabilization and increasing convective inhibition. ...Northeast/Mid-Atlantic... Dewpoints currently range from the low 70s over the northern Mid-Atlantic into the low 60s across northern NH/VT. Thunderstorms are already developing within this moist and moderately buoyant airmass as large-scale ascent attendant to upper troughing advancing eastward over Ontario/Quebec glances the region. Deep-layer vertical shear is expected to remain weak throughout the day (i.e. effective bulk shear generally less than 25 kt), which should limit overall storm strength and organization. Even so, steep low-level lapse rates could aid in the development of occasionally damaging gusts with any of the deeper convective cores. Greater buoyancy could result in a relatively higher probability for damaging gusts from the NY Hudson Valley into eastern PA/NJ. Refer to recently issued MCD #1938 for additional information. ..Mosier/Squitieri.. 08/13/2025 Read more

SPC Aug 13, 2025 1630 UTC Day 1 Convective Outlook

1 week 5 days ago
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook RESENT 1 NWS Storm Prediction Center Norman OK 1146 AM CDT Wed Aug 13 2025 Valid 131630Z - 141200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTH DAKOTA AND NORTH-CENTRAL NEBRASKA... ...SUMMARY... Scattered severe wind gusts and isolated large hail may occur across parts of the northern/central Plains this evening and overnight. Thunderstorms across portions of the Northeast and Mid-Atlantic may produce occasional damaging winds this afternoon. ...Northern/Central Plains... Recent satellite imagery shows a low-amplitude shortwave trough moving through southwest MT. This shortwave is forecast to continue eastward along the MT/WY border vicinity today, before continuing through the Dakotas/NE tonight. The airmass preceding this shortwave across southeast MT/northeast WY is relatively dry, with dewpoints currently in the low to mid 50s. Greater low-level moisture is in place farther east, with dewpoints increasing into the low 60s across south-central SD and north-central NE. Southerly low-level flow is anticipated throughout the day, helping to offset some of the mixing expected amid strong diurnal heating. This should result in a modestly moist, deeply mixed airmass across the southeast MT/northeast WY/western SD vicinity by the late afternoon when the forcing for ascent attendant to the approaching shortwave reaches the region. This modest large-scale ascent show work in tandem with robust daytime heating and localized orographic effects near the Black Hills to initiate thunderstorms. High-based storms are anticipated initially, which could result in strong outflow with any more mature storms. A few instances of hail as possible as well. Greater low-level moisture and buoyancy will be in place farther east (i.e. into more of western/central SD), which will combine with persistent large-scale forcing for ascent and a strengthening low-level jet to support upscale growth into a convective line. This should foster a continued threat for damaging gusts into south-central SD and far north-central NE this evening. The threat should diminish with eastern extent given nocturnal stabilization and increasing convective inhibition. ...Northeast/Mid-Atlantic... Dewpoints currently range from the low 70s over the northern Mid-Atlantic into the low 60s across northern NH/VT. Thunderstorms are already developing within this moist and moderately buoyant airmass as large-scale ascent attendant to upper troughing advancing eastward over Ontario/Quebec glances the region. Deep-layer vertical shear is expected to remain weak throughout the day (i.e. effective bulk shear generally less than 25 kt), which should limit overall storm strength and organization. Even so, steep low-level lapse rates could aid in the development of occasionally damaging gusts with any of the deeper convective cores. Greater buoyancy could result in a relatively higher probability for damaging gusts from the NY Hudson Valley into eastern PA/NJ. Refer to recently issued MCD #1938 for additional information. ..Mosier/Squitieri.. 08/13/2025 Read more

SPC Aug 13, 2025 1630 UTC Day 1 Convective Outlook

1 week 5 days ago
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook RESENT 1 NWS Storm Prediction Center Norman OK 1146 AM CDT Wed Aug 13 2025 Valid 131630Z - 141200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTH DAKOTA AND NORTH-CENTRAL NEBRASKA... ...SUMMARY... Scattered severe wind gusts and isolated large hail may occur across parts of the northern/central Plains this evening and overnight. Thunderstorms across portions of the Northeast and Mid-Atlantic may produce occasional damaging winds this afternoon. ...Northern/Central Plains... Recent satellite imagery shows a low-amplitude shortwave trough moving through southwest MT. This shortwave is forecast to continue eastward along the MT/WY border vicinity today, before continuing through the Dakotas/NE tonight. The airmass preceding this shortwave across southeast MT/northeast WY is relatively dry, with dewpoints currently in the low to mid 50s. Greater low-level moisture is in place farther east, with dewpoints increasing into the low 60s across south-central SD and north-central NE. Southerly low-level flow is anticipated throughout the day, helping to offset some of the mixing expected amid strong diurnal heating. This should result in a modestly moist, deeply mixed airmass across the southeast MT/northeast WY/western SD vicinity by the late afternoon when the forcing for ascent attendant to the approaching shortwave reaches the region. This modest large-scale ascent show work in tandem with robust daytime heating and localized orographic effects near the Black Hills to initiate thunderstorms. High-based storms are anticipated initially, which could result in strong outflow with any more mature storms. A few instances of hail as possible as well. Greater low-level moisture and buoyancy will be in place farther east (i.e. into more of western/central SD), which will combine with persistent large-scale forcing for ascent and a strengthening low-level jet to support upscale growth into a convective line. This should foster a continued threat for damaging gusts into south-central SD and far north-central NE this evening. The threat should diminish with eastern extent given nocturnal stabilization and increasing convective inhibition. ...Northeast/Mid-Atlantic... Dewpoints currently range from the low 70s over the northern Mid-Atlantic into the low 60s across northern NH/VT. Thunderstorms are already developing within this moist and moderately buoyant airmass as large-scale ascent attendant to upper troughing advancing eastward over Ontario/Quebec glances the region. Deep-layer vertical shear is expected to remain weak throughout the day (i.e. effective bulk shear generally less than 25 kt), which should limit overall storm strength and organization. Even so, steep low-level lapse rates could aid in the development of occasionally damaging gusts with any of the deeper convective cores. Greater buoyancy could result in a relatively higher probability for damaging gusts from the NY Hudson Valley into eastern PA/NJ. Refer to recently issued MCD #1938 for additional information. ..Mosier/Squitieri.. 08/13/2025 Read more

SPC Aug 13, 2025 1630 UTC Day 1 Convective Outlook

1 week 5 days ago
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook RESENT 1 NWS Storm Prediction Center Norman OK 1146 AM CDT Wed Aug 13 2025 Valid 131630Z - 141200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTH DAKOTA AND NORTH-CENTRAL NEBRASKA... ...SUMMARY... Scattered severe wind gusts and isolated large hail may occur across parts of the northern/central Plains this evening and overnight. Thunderstorms across portions of the Northeast and Mid-Atlantic may produce occasional damaging winds this afternoon. ...Northern/Central Plains... Recent satellite imagery shows a low-amplitude shortwave trough moving through southwest MT. This shortwave is forecast to continue eastward along the MT/WY border vicinity today, before continuing through the Dakotas/NE tonight. The airmass preceding this shortwave across southeast MT/northeast WY is relatively dry, with dewpoints currently in the low to mid 50s. Greater low-level moisture is in place farther east, with dewpoints increasing into the low 60s across south-central SD and north-central NE. Southerly low-level flow is anticipated throughout the day, helping to offset some of the mixing expected amid strong diurnal heating. This should result in a modestly moist, deeply mixed airmass across the southeast MT/northeast WY/western SD vicinity by the late afternoon when the forcing for ascent attendant to the approaching shortwave reaches the region. This modest large-scale ascent show work in tandem with robust daytime heating and localized orographic effects near the Black Hills to initiate thunderstorms. High-based storms are anticipated initially, which could result in strong outflow with any more mature storms. A few instances of hail as possible as well. Greater low-level moisture and buoyancy will be in place farther east (i.e. into more of western/central SD), which will combine with persistent large-scale forcing for ascent and a strengthening low-level jet to support upscale growth into a convective line. This should foster a continued threat for damaging gusts into south-central SD and far north-central NE this evening. The threat should diminish with eastern extent given nocturnal stabilization and increasing convective inhibition. ...Northeast/Mid-Atlantic... Dewpoints currently range from the low 70s over the northern Mid-Atlantic into the low 60s across northern NH/VT. Thunderstorms are already developing within this moist and moderately buoyant airmass as large-scale ascent attendant to upper troughing advancing eastward over Ontario/Quebec glances the region. Deep-layer vertical shear is expected to remain weak throughout the day (i.e. effective bulk shear generally less than 25 kt), which should limit overall storm strength and organization. Even so, steep low-level lapse rates could aid in the development of occasionally damaging gusts with any of the deeper convective cores. Greater buoyancy could result in a relatively higher probability for damaging gusts from the NY Hudson Valley into eastern PA/NJ. Refer to recently issued MCD #1938 for additional information. ..Mosier/Squitieri.. 08/13/2025 Read more

SPC Aug 13, 2025 1630 UTC Day 1 Convective Outlook

1 week 5 days ago
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook RESENT 1 NWS Storm Prediction Center Norman OK 1146 AM CDT Wed Aug 13 2025 Valid 131630Z - 141200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTH DAKOTA AND NORTH-CENTRAL NEBRASKA... ...SUMMARY... Scattered severe wind gusts and isolated large hail may occur across parts of the northern/central Plains this evening and overnight. Thunderstorms across portions of the Northeast and Mid-Atlantic may produce occasional damaging winds this afternoon. ...Northern/Central Plains... Recent satellite imagery shows a low-amplitude shortwave trough moving through southwest MT. This shortwave is forecast to continue eastward along the MT/WY border vicinity today, before continuing through the Dakotas/NE tonight. The airmass preceding this shortwave across southeast MT/northeast WY is relatively dry, with dewpoints currently in the low to mid 50s. Greater low-level moisture is in place farther east, with dewpoints increasing into the low 60s across south-central SD and north-central NE. Southerly low-level flow is anticipated throughout the day, helping to offset some of the mixing expected amid strong diurnal heating. This should result in a modestly moist, deeply mixed airmass across the southeast MT/northeast WY/western SD vicinity by the late afternoon when the forcing for ascent attendant to the approaching shortwave reaches the region. This modest large-scale ascent show work in tandem with robust daytime heating and localized orographic effects near the Black Hills to initiate thunderstorms. High-based storms are anticipated initially, which could result in strong outflow with any more mature storms. A few instances of hail as possible as well. Greater low-level moisture and buoyancy will be in place farther east (i.e. into more of western/central SD), which will combine with persistent large-scale forcing for ascent and a strengthening low-level jet to support upscale growth into a convective line. This should foster a continued threat for damaging gusts into south-central SD and far north-central NE this evening. The threat should diminish with eastern extent given nocturnal stabilization and increasing convective inhibition. ...Northeast/Mid-Atlantic... Dewpoints currently range from the low 70s over the northern Mid-Atlantic into the low 60s across northern NH/VT. Thunderstorms are already developing within this moist and moderately buoyant airmass as large-scale ascent attendant to upper troughing advancing eastward over Ontario/Quebec glances the region. Deep-layer vertical shear is expected to remain weak throughout the day (i.e. effective bulk shear generally less than 25 kt), which should limit overall storm strength and organization. Even so, steep low-level lapse rates could aid in the development of occasionally damaging gusts with any of the deeper convective cores. Greater buoyancy could result in a relatively higher probability for damaging gusts from the NY Hudson Valley into eastern PA/NJ. Refer to recently issued MCD #1938 for additional information. ..Mosier/Squitieri.. 08/13/2025 Read more