Severe Storms

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 PM CDT Wed Sep 10 2025 Valid 111200Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL ROCKIES TO THE NORTHERN PLAINS.... ...SUMMARY... Isolated strong to severe thunderstorms with hail and severe wind potential are possible across portions of the Rockies, central/northern High Plains into the Dakotas and northern Minnesota on Thursday. ...Synopsis... On Thursday, a large trough will be present across the western CONUS with a strong ridge across the Plains and troughing across the east. This pattern will shift slowly east through the day. Surface high pressure will dominate much of the eastern CONUS with lee troughing in the central and northern High Plains. ...Eastern Montana/northern Wyoming into the Dakotas and northern Minnesota... A cluster of storms may be ongoing across northern North Dakota at the start of the period. A moderate low-level jet is forecast to maintain intensity (and perhaps strengthen somewhat) during the day. This may result in maintenance of this cluster and restrengthening during the afternoon across southern Canada and perhaps into northern North Dakota and northern Minnesota. Moderate instability and moderate shear, combined with steep lapse rates, will support the potential for large hail and damaging wind gusts as these storms move east. Cooling temperatures aloft and steep lapse rates will lead to scattered to widespread thunderstorm development across much of the higher terrain across Wyoming and Montana. Modest deep-layer shear and a relatively dry profile will support the potential for some organized storms including supercells. These storms may produce isolated large hail and severe wind gusts. A more conditional severe environment will be present across eastern Wyoming/Montana and into the western Dakotas. Stronger instability (2000 to 3000 J/kg MLCAPE) is forecast across the region, but only weak height falls will be present with at least some residual capping from most forecast soundings. Some weak convergence/confluence will be present along the lee trough/dryline which could initiate a few storms. If storm form within this region, moderate deep-layer shear could support supercells capable of large hail and severe wind gusts. If this scenario appears more likely, a Slight Risk may be needed in later outlooks, particularly across eastern Montana and western North Dakota. ...Central Rockies... Moderate to strong shear will be present across the Rockies as a 45 to 60 knot mid-level jet streak overspreads the region. Weak height falls, terrain driven circulations, and weak diffluence aloft will combine for widespread thunderstorm development Thursday afternoon/evening. RAP forecast soundings show 500 to 750 J/kg MLCAPE and 1000-1300 J/kg MUCAPE at KGJT which is well above the 90th percentile and near the all time maximum for mid-September in GJT based on SPC sounding climatology. This abnormally unstable airmass combined with moderate shear will result in an environment capable of a few weak supercells producing isolated large hail and severe wind gusts across eastern Utah, the Four Corners region, much of Colorado, and southern Wyoming. ..Bentley.. 09/10/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 PM CDT Wed Sep 10 2025 Valid 111200Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL ROCKIES TO THE NORTHERN PLAINS.... ...SUMMARY... Isolated strong to severe thunderstorms with hail and severe wind potential are possible across portions of the Rockies, central/northern High Plains into the Dakotas and northern Minnesota on Thursday. ...Synopsis... On Thursday, a large trough will be present across the western CONUS with a strong ridge across the Plains and troughing across the east. This pattern will shift slowly east through the day. Surface high pressure will dominate much of the eastern CONUS with lee troughing in the central and northern High Plains. ...Eastern Montana/northern Wyoming into the Dakotas and northern Minnesota... A cluster of storms may be ongoing across northern North Dakota at the start of the period. A moderate low-level jet is forecast to maintain intensity (and perhaps strengthen somewhat) during the day. This may result in maintenance of this cluster and restrengthening during the afternoon across southern Canada and perhaps into northern North Dakota and northern Minnesota. Moderate instability and moderate shear, combined with steep lapse rates, will support the potential for large hail and damaging wind gusts as these storms move east. Cooling temperatures aloft and steep lapse rates will lead to scattered to widespread thunderstorm development across much of the higher terrain across Wyoming and Montana. Modest deep-layer shear and a relatively dry profile will support the potential for some organized storms including supercells. These storms may produce isolated large hail and severe wind gusts. A more conditional severe environment will be present across eastern Wyoming/Montana and into the western Dakotas. Stronger instability (2000 to 3000 J/kg MLCAPE) is forecast across the region, but only weak height falls will be present with at least some residual capping from most forecast soundings. Some weak convergence/confluence will be present along the lee trough/dryline which could initiate a few storms. If storm form within this region, moderate deep-layer shear could support supercells capable of large hail and severe wind gusts. If this scenario appears more likely, a Slight Risk may be needed in later outlooks, particularly across eastern Montana and western North Dakota. ...Central Rockies... Moderate to strong shear will be present across the Rockies as a 45 to 60 knot mid-level jet streak overspreads the region. Weak height falls, terrain driven circulations, and weak diffluence aloft will combine for widespread thunderstorm development Thursday afternoon/evening. RAP forecast soundings show 500 to 750 J/kg MLCAPE and 1000-1300 J/kg MUCAPE at KGJT which is well above the 90th percentile and near the all time maximum for mid-September in GJT based on SPC sounding climatology. This abnormally unstable airmass combined with moderate shear will result in an environment capable of a few weak supercells producing isolated large hail and severe wind gusts across eastern Utah, the Four Corners region, much of Colorado, and southern Wyoming. ..Bentley.. 09/10/2025 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1150 AM CDT Wed Sep 10 2025 Valid 101700Z - 111200Z ...Washington... Isolated thunderstorms are expected along the higher terrain of the Cascade Range in central and north-central WA this afternoon. PWAT values in the 0.65-0.85 inch range will support wetting rain cores in slower moving thunderstorms. However, lightning strikes outside of heavier precipitation cores could lead to some new ignitions in drought stressed, heavier fuels. Gusty outflow winds could also impact existing active fires in the Washington Cascades this afternoon. ...Eastern Nevada/western Utah... An advancing mid-level jet, relatively dry boundary layer and daytime mixing will support strong, sustained south to southwest winds of up to 25 mph across eastern NV and western UT this afternoon. Daytime relative humidity as low as 10% combined with the south to southwest winds will support an elevated fire weather threat across this region, despite marginal fuel dryness. A slight northward expansion of Elevated highlights into far northwestern UT and far south central ID was prudent based on latest model guidance and current relative humidity in northwestern UT already below 15%. ..Williams.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1245 AM CDT Wed Sep 10 2025/ ...Synopsis... The upper-level trough in the West will continue its slow eastward progress into the Great Basin. The mid-level jet will intensify within the southern and eastern Great Basin. Cooler air aloft and marginal mid-level ascent will also promote some convection in Washington. ...Washington... A pocket of drier fuels exists in the Columbia Basin and nearby vicinity. Recent lightning activity has led to fire starts. Given the current convection in Oregon moving north and west around the upper-low, some lightning activity can be expected early this morning. Additional thunderstorms appear possible during the afternoon and perhaps again overnight tonight. However, those storms may pose a lesser lightning ignition threat given increasing PWAT values through the period. ...Eastern Nevada/western Utah... Strong surface winds of 15-25 mph will overspread parts of the Great Basin beneath the mid-level jet. RH could fall near 10% locally, but 15-20% will be more common. Given the potential for critical meteorological conditions, elevated fire weather concerns are expected despite the unfavorable to marginal fuel receptiveness in these areas. ...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 1150 AM CDT Wed Sep 10 2025 Valid 101700Z - 111200Z ...Washington... Isolated thunderstorms are expected along the higher terrain of the Cascade Range in central and north-central WA this afternoon. PWAT values in the 0.65-0.85 inch range will support wetting rain cores in slower moving thunderstorms. However, lightning strikes outside of heavier precipitation cores could lead to some new ignitions in drought stressed, heavier fuels. Gusty outflow winds could also impact existing active fires in the Washington Cascades this afternoon. ...Eastern Nevada/western Utah... An advancing mid-level jet, relatively dry boundary layer and daytime mixing will support strong, sustained south to southwest winds of up to 25 mph across eastern NV and western UT this afternoon. Daytime relative humidity as low as 10% combined with the south to southwest winds will support an elevated fire weather threat across this region, despite marginal fuel dryness. A slight northward expansion of Elevated highlights into far northwestern UT and far south central ID was prudent based on latest model guidance and current relative humidity in northwestern UT already below 15%. ..Williams.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1245 AM CDT Wed Sep 10 2025/ ...Synopsis... The upper-level trough in the West will continue its slow eastward progress into the Great Basin. The mid-level jet will intensify within the southern and eastern Great Basin. Cooler air aloft and marginal mid-level ascent will also promote some convection in Washington. ...Washington... A pocket of drier fuels exists in the Columbia Basin and nearby vicinity. Recent lightning activity has led to fire starts. Given the current convection in Oregon moving north and west around the upper-low, some lightning activity can be expected early this morning. Additional thunderstorms appear possible during the afternoon and perhaps again overnight tonight. However, those storms may pose a lesser lightning ignition threat given increasing PWAT values through the period. ...Eastern Nevada/western Utah... Strong surface winds of 15-25 mph will overspread parts of the Great Basin beneath the mid-level jet. RH could fall near 10% locally, but 15-20% will be more common. Given the potential for critical meteorological conditions, elevated fire weather concerns are expected despite the unfavorable to marginal fuel receptiveness in these areas. ...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 1150 AM CDT Wed Sep 10 2025 Valid 101700Z - 111200Z ...Washington... Isolated thunderstorms are expected along the higher terrain of the Cascade Range in central and north-central WA this afternoon. PWAT values in the 0.65-0.85 inch range will support wetting rain cores in slower moving thunderstorms. However, lightning strikes outside of heavier precipitation cores could lead to some new ignitions in drought stressed, heavier fuels. Gusty outflow winds could also impact existing active fires in the Washington Cascades this afternoon. ...Eastern Nevada/western Utah... An advancing mid-level jet, relatively dry boundary layer and daytime mixing will support strong, sustained south to southwest winds of up to 25 mph across eastern NV and western UT this afternoon. Daytime relative humidity as low as 10% combined with the south to southwest winds will support an elevated fire weather threat across this region, despite marginal fuel dryness. A slight northward expansion of Elevated highlights into far northwestern UT and far south central ID was prudent based on latest model guidance and current relative humidity in northwestern UT already below 15%. ..Williams.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1245 AM CDT Wed Sep 10 2025/ ...Synopsis... The upper-level trough in the West will continue its slow eastward progress into the Great Basin. The mid-level jet will intensify within the southern and eastern Great Basin. Cooler air aloft and marginal mid-level ascent will also promote some convection in Washington. ...Washington... A pocket of drier fuels exists in the Columbia Basin and nearby vicinity. Recent lightning activity has led to fire starts. Given the current convection in Oregon moving north and west around the upper-low, some lightning activity can be expected early this morning. Additional thunderstorms appear possible during the afternoon and perhaps again overnight tonight. However, those storms may pose a lesser lightning ignition threat given increasing PWAT values through the period. ...Eastern Nevada/western Utah... Strong surface winds of 15-25 mph will overspread parts of the Great Basin beneath the mid-level jet. RH could fall near 10% locally, but 15-20% will be more common. Given the potential for critical meteorological conditions, elevated fire weather concerns are expected despite the unfavorable to marginal fuel receptiveness in these areas. ...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 1150 AM CDT Wed Sep 10 2025 Valid 101700Z - 111200Z ...Washington... Isolated thunderstorms are expected along the higher terrain of the Cascade Range in central and north-central WA this afternoon. PWAT values in the 0.65-0.85 inch range will support wetting rain cores in slower moving thunderstorms. However, lightning strikes outside of heavier precipitation cores could lead to some new ignitions in drought stressed, heavier fuels. Gusty outflow winds could also impact existing active fires in the Washington Cascades this afternoon. ...Eastern Nevada/western Utah... An advancing mid-level jet, relatively dry boundary layer and daytime mixing will support strong, sustained south to southwest winds of up to 25 mph across eastern NV and western UT this afternoon. Daytime relative humidity as low as 10% combined with the south to southwest winds will support an elevated fire weather threat across this region, despite marginal fuel dryness. A slight northward expansion of Elevated highlights into far northwestern UT and far south central ID was prudent based on latest model guidance and current relative humidity in northwestern UT already below 15%. ..Williams.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1245 AM CDT Wed Sep 10 2025/ ...Synopsis... The upper-level trough in the West will continue its slow eastward progress into the Great Basin. The mid-level jet will intensify within the southern and eastern Great Basin. Cooler air aloft and marginal mid-level ascent will also promote some convection in Washington. ...Washington... A pocket of drier fuels exists in the Columbia Basin and nearby vicinity. Recent lightning activity has led to fire starts. Given the current convection in Oregon moving north and west around the upper-low, some lightning activity can be expected early this morning. Additional thunderstorms appear possible during the afternoon and perhaps again overnight tonight. However, those storms may pose a lesser lightning ignition threat given increasing PWAT values through the period. ...Eastern Nevada/western Utah... Strong surface winds of 15-25 mph will overspread parts of the Great Basin beneath the mid-level jet. RH could fall near 10% locally, but 15-20% will be more common. Given the potential for critical meteorological conditions, elevated fire weather concerns are expected despite the unfavorable to marginal fuel receptiveness in these areas. ...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 1150 AM CDT Wed Sep 10 2025 Valid 101700Z - 111200Z ...Washington... Isolated thunderstorms are expected along the higher terrain of the Cascade Range in central and north-central WA this afternoon. PWAT values in the 0.65-0.85 inch range will support wetting rain cores in slower moving thunderstorms. However, lightning strikes outside of heavier precipitation cores could lead to some new ignitions in drought stressed, heavier fuels. Gusty outflow winds could also impact existing active fires in the Washington Cascades this afternoon. ...Eastern Nevada/western Utah... An advancing mid-level jet, relatively dry boundary layer and daytime mixing will support strong, sustained south to southwest winds of up to 25 mph across eastern NV and western UT this afternoon. Daytime relative humidity as low as 10% combined with the south to southwest winds will support an elevated fire weather threat across this region, despite marginal fuel dryness. A slight northward expansion of Elevated highlights into far northwestern UT and far south central ID was prudent based on latest model guidance and current relative humidity in northwestern UT already below 15%. ..Williams.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1245 AM CDT Wed Sep 10 2025/ ...Synopsis... The upper-level trough in the West will continue its slow eastward progress into the Great Basin. The mid-level jet will intensify within the southern and eastern Great Basin. Cooler air aloft and marginal mid-level ascent will also promote some convection in Washington. ...Washington... A pocket of drier fuels exists in the Columbia Basin and nearby vicinity. Recent lightning activity has led to fire starts. Given the current convection in Oregon moving north and west around the upper-low, some lightning activity can be expected early this morning. Additional thunderstorms appear possible during the afternoon and perhaps again overnight tonight. However, those storms may pose a lesser lightning ignition threat given increasing PWAT values through the period. ...Eastern Nevada/western Utah... Strong surface winds of 15-25 mph will overspread parts of the Great Basin beneath the mid-level jet. RH could fall near 10% locally, but 15-20% will be more common. Given the potential for critical meteorological conditions, elevated fire weather concerns are expected despite the unfavorable to marginal fuel receptiveness in these areas. ...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 1150 AM CDT Wed Sep 10 2025 Valid 101700Z - 111200Z ...Washington... Isolated thunderstorms are expected along the higher terrain of the Cascade Range in central and north-central WA this afternoon. PWAT values in the 0.65-0.85 inch range will support wetting rain cores in slower moving thunderstorms. However, lightning strikes outside of heavier precipitation cores could lead to some new ignitions in drought stressed, heavier fuels. Gusty outflow winds could also impact existing active fires in the Washington Cascades this afternoon. ...Eastern Nevada/western Utah... An advancing mid-level jet, relatively dry boundary layer and daytime mixing will support strong, sustained south to southwest winds of up to 25 mph across eastern NV and western UT this afternoon. Daytime relative humidity as low as 10% combined with the south to southwest winds will support an elevated fire weather threat across this region, despite marginal fuel dryness. A slight northward expansion of Elevated highlights into far northwestern UT and far south central ID was prudent based on latest model guidance and current relative humidity in northwestern UT already below 15%. ..Williams.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1245 AM CDT Wed Sep 10 2025/ ...Synopsis... The upper-level trough in the West will continue its slow eastward progress into the Great Basin. The mid-level jet will intensify within the southern and eastern Great Basin. Cooler air aloft and marginal mid-level ascent will also promote some convection in Washington. ...Washington... A pocket of drier fuels exists in the Columbia Basin and nearby vicinity. Recent lightning activity has led to fire starts. Given the current convection in Oregon moving north and west around the upper-low, some lightning activity can be expected early this morning. Additional thunderstorms appear possible during the afternoon and perhaps again overnight tonight. However, those storms may pose a lesser lightning ignition threat given increasing PWAT values through the period. ...Eastern Nevada/western Utah... Strong surface winds of 15-25 mph will overspread parts of the Great Basin beneath the mid-level jet. RH could fall near 10% locally, but 15-20% will be more common. Given the potential for critical meteorological conditions, elevated fire weather concerns are expected despite the unfavorable to marginal fuel receptiveness in these areas. ...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 1150 AM CDT Wed Sep 10 2025 Valid 101700Z - 111200Z ...Washington... Isolated thunderstorms are expected along the higher terrain of the Cascade Range in central and north-central WA this afternoon. PWAT values in the 0.65-0.85 inch range will support wetting rain cores in slower moving thunderstorms. However, lightning strikes outside of heavier precipitation cores could lead to some new ignitions in drought stressed, heavier fuels. Gusty outflow winds could also impact existing active fires in the Washington Cascades this afternoon. ...Eastern Nevada/western Utah... An advancing mid-level jet, relatively dry boundary layer and daytime mixing will support strong, sustained south to southwest winds of up to 25 mph across eastern NV and western UT this afternoon. Daytime relative humidity as low as 10% combined with the south to southwest winds will support an elevated fire weather threat across this region, despite marginal fuel dryness. A slight northward expansion of Elevated highlights into far northwestern UT and far south central ID was prudent based on latest model guidance and current relative humidity in northwestern UT already below 15%. ..Williams.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1245 AM CDT Wed Sep 10 2025/ ...Synopsis... The upper-level trough in the West will continue its slow eastward progress into the Great Basin. The mid-level jet will intensify within the southern and eastern Great Basin. Cooler air aloft and marginal mid-level ascent will also promote some convection in Washington. ...Washington... A pocket of drier fuels exists in the Columbia Basin and nearby vicinity. Recent lightning activity has led to fire starts. Given the current convection in Oregon moving north and west around the upper-low, some lightning activity can be expected early this morning. Additional thunderstorms appear possible during the afternoon and perhaps again overnight tonight. However, those storms may pose a lesser lightning ignition threat given increasing PWAT values through the period. ...Eastern Nevada/western Utah... Strong surface winds of 15-25 mph will overspread parts of the Great Basin beneath the mid-level jet. RH could fall near 10% locally, but 15-20% will be more common. Given the potential for critical meteorological conditions, elevated fire weather concerns are expected despite the unfavorable to marginal fuel receptiveness in these areas. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Wed Sep 10 2025 Valid 101630Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. ..Guyer/Weinman.. 09/10/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Wed Sep 10 2025 Valid 101630Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. ..Guyer/Weinman.. 09/10/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Wed Sep 10 2025 Valid 101630Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. ..Guyer/Weinman.. 09/10/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Wed Sep 10 2025 Valid 101630Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. ..Guyer/Weinman.. 09/10/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Wed Sep 10 2025 Valid 101630Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. ..Guyer/Weinman.. 09/10/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Wed Sep 10 2025 Valid 101630Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. ..Guyer/Weinman.. 09/10/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0745 AM CDT Wed Sep 10 2025 Valid 101300Z - 111200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered showers and thunderstorms are possible over parts of the Northwest and northern Rockies with more isolated storms over the High Plains. Severe potential is generally low. ...Synopsis... Water-vapor imagery this morning shows an upper low situated over northern CA, and it will remain nearly stationary during the period with a large area of cyclonic flow extending from southern CA into the eastern Great Basin and central Rockies. A downstream upper ridge over the High Plains will feature a lee trough that will act to focus isolated to scattered thunderstorms from MT southward into the central High Plains. Strong heating and weak upslope flow beneath the aforementioned upper-level ridge will favor a few isolated cells developing during peak heating. A couple of the more vigorous storms may be capable of localized strong gusts near 1) NM/OK/TX/CO border, 2) east of the CO Front Range in the High Plains, and 3) in eastern WY. Warming aloft is expected to mitigate the overall potential with these storms. Farther west, a mid-level shortwave trough will move through the base of the West Coast mid- to upper low/trough and to near the UT/NV border by late afternoon/early evening. A corresponding belt of 50-kt southwesterly 500-mb flow will overspread western UT. Isolated dry microbursts may accompany the stronger storms over central UT into western CO during the 22-02z period. Elsewhere, scattered afternoon storms will occur beneath the upper trough from northern NV into OR and western ID, and a few of these storms could produce at least small hail given such cool temperatures aloft and modest deep-layer shear. ..Smith/Broyles.. 09/10/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0745 AM CDT Wed Sep 10 2025 Valid 101300Z - 111200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered showers and thunderstorms are possible over parts of the Northwest and northern Rockies with more isolated storms over the High Plains. Severe potential is generally low. ...Synopsis... Water-vapor imagery this morning shows an upper low situated over northern CA, and it will remain nearly stationary during the period with a large area of cyclonic flow extending from southern CA into the eastern Great Basin and central Rockies. A downstream upper ridge over the High Plains will feature a lee trough that will act to focus isolated to scattered thunderstorms from MT southward into the central High Plains. Strong heating and weak upslope flow beneath the aforementioned upper-level ridge will favor a few isolated cells developing during peak heating. A couple of the more vigorous storms may be capable of localized strong gusts near 1) NM/OK/TX/CO border, 2) east of the CO Front Range in the High Plains, and 3) in eastern WY. Warming aloft is expected to mitigate the overall potential with these storms. Farther west, a mid-level shortwave trough will move through the base of the West Coast mid- to upper low/trough and to near the UT/NV border by late afternoon/early evening. A corresponding belt of 50-kt southwesterly 500-mb flow will overspread western UT. Isolated dry microbursts may accompany the stronger storms over central UT into western CO during the 22-02z period. Elsewhere, scattered afternoon storms will occur beneath the upper trough from northern NV into OR and western ID, and a few of these storms could produce at least small hail given such cool temperatures aloft and modest deep-layer shear. ..Smith/Broyles.. 09/10/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0745 AM CDT Wed Sep 10 2025 Valid 101300Z - 111200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered showers and thunderstorms are possible over parts of the Northwest and northern Rockies with more isolated storms over the High Plains. Severe potential is generally low. ...Synopsis... Water-vapor imagery this morning shows an upper low situated over northern CA, and it will remain nearly stationary during the period with a large area of cyclonic flow extending from southern CA into the eastern Great Basin and central Rockies. A downstream upper ridge over the High Plains will feature a lee trough that will act to focus isolated to scattered thunderstorms from MT southward into the central High Plains. Strong heating and weak upslope flow beneath the aforementioned upper-level ridge will favor a few isolated cells developing during peak heating. A couple of the more vigorous storms may be capable of localized strong gusts near 1) NM/OK/TX/CO border, 2) east of the CO Front Range in the High Plains, and 3) in eastern WY. Warming aloft is expected to mitigate the overall potential with these storms. Farther west, a mid-level shortwave trough will move through the base of the West Coast mid- to upper low/trough and to near the UT/NV border by late afternoon/early evening. A corresponding belt of 50-kt southwesterly 500-mb flow will overspread western UT. Isolated dry microbursts may accompany the stronger storms over central UT into western CO during the 22-02z period. Elsewhere, scattered afternoon storms will occur beneath the upper trough from northern NV into OR and western ID, and a few of these storms could produce at least small hail given such cool temperatures aloft and modest deep-layer shear. ..Smith/Broyles.. 09/10/2025 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Sep 10 2025 Valid 131200Z - 181200Z ...DISCUSSION... Severe potential in the extended forecast period will be tied to a shortwave trough and stronger southwesterly flow aloft emanating from the Rockies over the central US. Flow aloft will increase D4/Saturday as the upper trough begins to overspread the central US. Ascent from the trough will maintain a weak surface low and stationary front over the northern Plains and Upper Midwest. At the same time, a weak cold front will move eastward over the High Plains serving as a focus for thunderstorm development from the Dakotas and MN to the southern Plains each afternoon. Some isolated severe potential is apparent near the surface low/stalled front over the northern Plains and along the cold front farther south through the remainder of the weekend. However, model guidance varies widely on available moisture/buoyancy and the overlap with more robust vertical shear. This continues to cast significant uncertainty on severe probabilities through the first half of the extended forecast period. By early next week, mid-level ridging is expected to strengthen, forcing stronger flow aloft northward as the primary western trough begins to weaken. A second trough will stall over the West as the ridge continues to build. This should favor drier surface conditions while also limiting the overlap of buoyancy with stronger flow aloft. Severe potential appears limited beyond this weekend and into the first half of next week. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Sep 10 2025 Valid 131200Z - 181200Z ...DISCUSSION... Severe potential in the extended forecast period will be tied to a shortwave trough and stronger southwesterly flow aloft emanating from the Rockies over the central US. Flow aloft will increase D4/Saturday as the upper trough begins to overspread the central US. Ascent from the trough will maintain a weak surface low and stationary front over the northern Plains and Upper Midwest. At the same time, a weak cold front will move eastward over the High Plains serving as a focus for thunderstorm development from the Dakotas and MN to the southern Plains each afternoon. Some isolated severe potential is apparent near the surface low/stalled front over the northern Plains and along the cold front farther south through the remainder of the weekend. However, model guidance varies widely on available moisture/buoyancy and the overlap with more robust vertical shear. This continues to cast significant uncertainty on severe probabilities through the first half of the extended forecast period. By early next week, mid-level ridging is expected to strengthen, forcing stronger flow aloft northward as the primary western trough begins to weaken. A second trough will stall over the West as the ridge continues to build. This should favor drier surface conditions while also limiting the overlap of buoyancy with stronger flow aloft. Severe potential appears limited beyond this weekend and into the first half of next week. Read more