Severe Storms

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Fri Sep 05 2025 Valid 051630Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE TENNESSEE VALLEY AND UPPER OHIO VALLEY... ...SUMMARY... Scattered damaging winds, isolated severe hail, and a brief tornado or two are possible from the Upper Ohio to Tennessee Valleys, mainly late this afternoon and evening. ...Ohio Valley/Central Appalachians to the Tennessee Valley... A large-scale upper trough/low will remain centered over Ontario today, with mid/upper-level troughing extending southward across much of the Great Lakes/Midwest into the OH Valley. A cold front will continue to advance slowly southeastward across portions of the Mid-South and OH Valley through this evening. Daytime heating of a seasonably moist low-level airmass ahead of this front over the TN Valley will likely yield upwards of 1500-2500 J/kg MLCAPE by late afternoon, mainly in KY/TN. Weaker instability is forecast with northward extent into the upper OH Valley and central Appalachians. Forcing for ascent aloft will remain nebulous for much of the day, with generally neutral mid-level heights and stronger flow remaining confined to the north of the surface cold front. Still, a subtle mid-level perturbation over eastern KS and the Ozarks late this morning should continue eastward towards the Mid-South and lower OH Valley by late afternoon/early evening. This feature, along with modest low-level convergence along the front, may be sufficient to encourage initial convective development by 21-23Z across parts of KY/TN. Even with stronger flow aloft remaining displaced to the north of the surface warm sector, some veering and gradual strengthening with height through mid/upper levels should support sufficient deep-layer shear for updraft organization. Current expectations are for multiple clusters to develop and pose a risk for mainly severe/damaging winds as they spread eastward across the TN and upper OH Valleys through the late afternoon and evening. With cool temperatures aloft and marginal deep-layer shear to support supercells, some of this activity could also pose a threat for isolated hail, especially any cells that can remain at least semi-discrete. A brief tornado or two also appears possible, although low-level shear should remain fairly limited given veered/west-southwesterly low-level flow. With a relatively narrow warm sector expected, convection should generally weaken this evening as it moves into the higher terrain of the central Appalachians and encounters a less unstable airmass. ...Mid-South to North Texas... An elongated mid-level thermal trough, characterized by 500 mb temperatures around -8 to -12 C per RAP analysis and 12Z OUN/FWD observed soundings, extends into much of OK and north TX, well to the south of the vertically stacked cyclone over Ontario. Low to mid-level flow should remain modest across this region, with some signal from various NAM/RAP forecast soundings of a veer-back-veer signature. Strong speed shear should remain confined above 500 mb, coincident with poor upper-level lapse rates atop steeper mid-level lapse rates. This suggests a messy convective mode should be common as convection increases in the late afternoon and evening, along the more west/east-oriented portion of the surface cold front. Have maintained the Marginal Risk for an isolated severe hail/wind threat with a small westward expansion with this update. ...Oregon... Isolated to scattered thunderstorms should develop today across parts of OR as a weak mid-level trough moves northward across the Pacific Northwest Coast. While low/mid-level flow is expected to remain rather modest, steepened low-level lapse rates could support isolated strong/gusty winds with any high-based convection that develops this afternoon/evening. ..Gleason/Weinman.. 09/05/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Fri Sep 05 2025 Valid 051630Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE TENNESSEE VALLEY AND UPPER OHIO VALLEY... ...SUMMARY... Scattered damaging winds, isolated severe hail, and a brief tornado or two are possible from the Upper Ohio to Tennessee Valleys, mainly late this afternoon and evening. ...Ohio Valley/Central Appalachians to the Tennessee Valley... A large-scale upper trough/low will remain centered over Ontario today, with mid/upper-level troughing extending southward across much of the Great Lakes/Midwest into the OH Valley. A cold front will continue to advance slowly southeastward across portions of the Mid-South and OH Valley through this evening. Daytime heating of a seasonably moist low-level airmass ahead of this front over the TN Valley will likely yield upwards of 1500-2500 J/kg MLCAPE by late afternoon, mainly in KY/TN. Weaker instability is forecast with northward extent into the upper OH Valley and central Appalachians. Forcing for ascent aloft will remain nebulous for much of the day, with generally neutral mid-level heights and stronger flow remaining confined to the north of the surface cold front. Still, a subtle mid-level perturbation over eastern KS and the Ozarks late this morning should continue eastward towards the Mid-South and lower OH Valley by late afternoon/early evening. This feature, along with modest low-level convergence along the front, may be sufficient to encourage initial convective development by 21-23Z across parts of KY/TN. Even with stronger flow aloft remaining displaced to the north of the surface warm sector, some veering and gradual strengthening with height through mid/upper levels should support sufficient deep-layer shear for updraft organization. Current expectations are for multiple clusters to develop and pose a risk for mainly severe/damaging winds as they spread eastward across the TN and upper OH Valleys through the late afternoon and evening. With cool temperatures aloft and marginal deep-layer shear to support supercells, some of this activity could also pose a threat for isolated hail, especially any cells that can remain at least semi-discrete. A brief tornado or two also appears possible, although low-level shear should remain fairly limited given veered/west-southwesterly low-level flow. With a relatively narrow warm sector expected, convection should generally weaken this evening as it moves into the higher terrain of the central Appalachians and encounters a less unstable airmass. ...Mid-South to North Texas... An elongated mid-level thermal trough, characterized by 500 mb temperatures around -8 to -12 C per RAP analysis and 12Z OUN/FWD observed soundings, extends into much of OK and north TX, well to the south of the vertically stacked cyclone over Ontario. Low to mid-level flow should remain modest across this region, with some signal from various NAM/RAP forecast soundings of a veer-back-veer signature. Strong speed shear should remain confined above 500 mb, coincident with poor upper-level lapse rates atop steeper mid-level lapse rates. This suggests a messy convective mode should be common as convection increases in the late afternoon and evening, along the more west/east-oriented portion of the surface cold front. Have maintained the Marginal Risk for an isolated severe hail/wind threat with a small westward expansion with this update. ...Oregon... Isolated to scattered thunderstorms should develop today across parts of OR as a weak mid-level trough moves northward across the Pacific Northwest Coast. While low/mid-level flow is expected to remain rather modest, steepened low-level lapse rates could support isolated strong/gusty winds with any high-based convection that develops this afternoon/evening. ..Gleason/Weinman.. 09/05/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Fri Sep 05 2025 Valid 051630Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE TENNESSEE VALLEY AND UPPER OHIO VALLEY... ...SUMMARY... Scattered damaging winds, isolated severe hail, and a brief tornado or two are possible from the Upper Ohio to Tennessee Valleys, mainly late this afternoon and evening. ...Ohio Valley/Central Appalachians to the Tennessee Valley... A large-scale upper trough/low will remain centered over Ontario today, with mid/upper-level troughing extending southward across much of the Great Lakes/Midwest into the OH Valley. A cold front will continue to advance slowly southeastward across portions of the Mid-South and OH Valley through this evening. Daytime heating of a seasonably moist low-level airmass ahead of this front over the TN Valley will likely yield upwards of 1500-2500 J/kg MLCAPE by late afternoon, mainly in KY/TN. Weaker instability is forecast with northward extent into the upper OH Valley and central Appalachians. Forcing for ascent aloft will remain nebulous for much of the day, with generally neutral mid-level heights and stronger flow remaining confined to the north of the surface cold front. Still, a subtle mid-level perturbation over eastern KS and the Ozarks late this morning should continue eastward towards the Mid-South and lower OH Valley by late afternoon/early evening. This feature, along with modest low-level convergence along the front, may be sufficient to encourage initial convective development by 21-23Z across parts of KY/TN. Even with stronger flow aloft remaining displaced to the north of the surface warm sector, some veering and gradual strengthening with height through mid/upper levels should support sufficient deep-layer shear for updraft organization. Current expectations are for multiple clusters to develop and pose a risk for mainly severe/damaging winds as they spread eastward across the TN and upper OH Valleys through the late afternoon and evening. With cool temperatures aloft and marginal deep-layer shear to support supercells, some of this activity could also pose a threat for isolated hail, especially any cells that can remain at least semi-discrete. A brief tornado or two also appears possible, although low-level shear should remain fairly limited given veered/west-southwesterly low-level flow. With a relatively narrow warm sector expected, convection should generally weaken this evening as it moves into the higher terrain of the central Appalachians and encounters a less unstable airmass. ...Mid-South to North Texas... An elongated mid-level thermal trough, characterized by 500 mb temperatures around -8 to -12 C per RAP analysis and 12Z OUN/FWD observed soundings, extends into much of OK and north TX, well to the south of the vertically stacked cyclone over Ontario. Low to mid-level flow should remain modest across this region, with some signal from various NAM/RAP forecast soundings of a veer-back-veer signature. Strong speed shear should remain confined above 500 mb, coincident with poor upper-level lapse rates atop steeper mid-level lapse rates. This suggests a messy convective mode should be common as convection increases in the late afternoon and evening, along the more west/east-oriented portion of the surface cold front. Have maintained the Marginal Risk for an isolated severe hail/wind threat with a small westward expansion with this update. ...Oregon... Isolated to scattered thunderstorms should develop today across parts of OR as a weak mid-level trough moves northward across the Pacific Northwest Coast. While low/mid-level flow is expected to remain rather modest, steepened low-level lapse rates could support isolated strong/gusty winds with any high-based convection that develops this afternoon/evening. ..Gleason/Weinman.. 09/05/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Fri Sep 05 2025 Valid 051630Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE TENNESSEE VALLEY AND UPPER OHIO VALLEY... ...SUMMARY... Scattered damaging winds, isolated severe hail, and a brief tornado or two are possible from the Upper Ohio to Tennessee Valleys, mainly late this afternoon and evening. ...Ohio Valley/Central Appalachians to the Tennessee Valley... A large-scale upper trough/low will remain centered over Ontario today, with mid/upper-level troughing extending southward across much of the Great Lakes/Midwest into the OH Valley. A cold front will continue to advance slowly southeastward across portions of the Mid-South and OH Valley through this evening. Daytime heating of a seasonably moist low-level airmass ahead of this front over the TN Valley will likely yield upwards of 1500-2500 J/kg MLCAPE by late afternoon, mainly in KY/TN. Weaker instability is forecast with northward extent into the upper OH Valley and central Appalachians. Forcing for ascent aloft will remain nebulous for much of the day, with generally neutral mid-level heights and stronger flow remaining confined to the north of the surface cold front. Still, a subtle mid-level perturbation over eastern KS and the Ozarks late this morning should continue eastward towards the Mid-South and lower OH Valley by late afternoon/early evening. This feature, along with modest low-level convergence along the front, may be sufficient to encourage initial convective development by 21-23Z across parts of KY/TN. Even with stronger flow aloft remaining displaced to the north of the surface warm sector, some veering and gradual strengthening with height through mid/upper levels should support sufficient deep-layer shear for updraft organization. Current expectations are for multiple clusters to develop and pose a risk for mainly severe/damaging winds as they spread eastward across the TN and upper OH Valleys through the late afternoon and evening. With cool temperatures aloft and marginal deep-layer shear to support supercells, some of this activity could also pose a threat for isolated hail, especially any cells that can remain at least semi-discrete. A brief tornado or two also appears possible, although low-level shear should remain fairly limited given veered/west-southwesterly low-level flow. With a relatively narrow warm sector expected, convection should generally weaken this evening as it moves into the higher terrain of the central Appalachians and encounters a less unstable airmass. ...Mid-South to North Texas... An elongated mid-level thermal trough, characterized by 500 mb temperatures around -8 to -12 C per RAP analysis and 12Z OUN/FWD observed soundings, extends into much of OK and north TX, well to the south of the vertically stacked cyclone over Ontario. Low to mid-level flow should remain modest across this region, with some signal from various NAM/RAP forecast soundings of a veer-back-veer signature. Strong speed shear should remain confined above 500 mb, coincident with poor upper-level lapse rates atop steeper mid-level lapse rates. This suggests a messy convective mode should be common as convection increases in the late afternoon and evening, along the more west/east-oriented portion of the surface cold front. Have maintained the Marginal Risk for an isolated severe hail/wind threat with a small westward expansion with this update. ...Oregon... Isolated to scattered thunderstorms should develop today across parts of OR as a weak mid-level trough moves northward across the Pacific Northwest Coast. While low/mid-level flow is expected to remain rather modest, steepened low-level lapse rates could support isolated strong/gusty winds with any high-based convection that develops this afternoon/evening. ..Gleason/Weinman.. 09/05/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Fri Sep 05 2025 Valid 051630Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE TENNESSEE VALLEY AND UPPER OHIO VALLEY... ...SUMMARY... Scattered damaging winds, isolated severe hail, and a brief tornado or two are possible from the Upper Ohio to Tennessee Valleys, mainly late this afternoon and evening. ...Ohio Valley/Central Appalachians to the Tennessee Valley... A large-scale upper trough/low will remain centered over Ontario today, with mid/upper-level troughing extending southward across much of the Great Lakes/Midwest into the OH Valley. A cold front will continue to advance slowly southeastward across portions of the Mid-South and OH Valley through this evening. Daytime heating of a seasonably moist low-level airmass ahead of this front over the TN Valley will likely yield upwards of 1500-2500 J/kg MLCAPE by late afternoon, mainly in KY/TN. Weaker instability is forecast with northward extent into the upper OH Valley and central Appalachians. Forcing for ascent aloft will remain nebulous for much of the day, with generally neutral mid-level heights and stronger flow remaining confined to the north of the surface cold front. Still, a subtle mid-level perturbation over eastern KS and the Ozarks late this morning should continue eastward towards the Mid-South and lower OH Valley by late afternoon/early evening. This feature, along with modest low-level convergence along the front, may be sufficient to encourage initial convective development by 21-23Z across parts of KY/TN. Even with stronger flow aloft remaining displaced to the north of the surface warm sector, some veering and gradual strengthening with height through mid/upper levels should support sufficient deep-layer shear for updraft organization. Current expectations are for multiple clusters to develop and pose a risk for mainly severe/damaging winds as they spread eastward across the TN and upper OH Valleys through the late afternoon and evening. With cool temperatures aloft and marginal deep-layer shear to support supercells, some of this activity could also pose a threat for isolated hail, especially any cells that can remain at least semi-discrete. A brief tornado or two also appears possible, although low-level shear should remain fairly limited given veered/west-southwesterly low-level flow. With a relatively narrow warm sector expected, convection should generally weaken this evening as it moves into the higher terrain of the central Appalachians and encounters a less unstable airmass. ...Mid-South to North Texas... An elongated mid-level thermal trough, characterized by 500 mb temperatures around -8 to -12 C per RAP analysis and 12Z OUN/FWD observed soundings, extends into much of OK and north TX, well to the south of the vertically stacked cyclone over Ontario. Low to mid-level flow should remain modest across this region, with some signal from various NAM/RAP forecast soundings of a veer-back-veer signature. Strong speed shear should remain confined above 500 mb, coincident with poor upper-level lapse rates atop steeper mid-level lapse rates. This suggests a messy convective mode should be common as convection increases in the late afternoon and evening, along the more west/east-oriented portion of the surface cold front. Have maintained the Marginal Risk for an isolated severe hail/wind threat with a small westward expansion with this update. ...Oregon... Isolated to scattered thunderstorms should develop today across parts of OR as a weak mid-level trough moves northward across the Pacific Northwest Coast. While low/mid-level flow is expected to remain rather modest, steepened low-level lapse rates could support isolated strong/gusty winds with any high-based convection that develops this afternoon/evening. ..Gleason/Weinman.. 09/05/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Fri Sep 05 2025 Valid 051630Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE TENNESSEE VALLEY AND UPPER OHIO VALLEY... ...SUMMARY... Scattered damaging winds, isolated severe hail, and a brief tornado or two are possible from the Upper Ohio to Tennessee Valleys, mainly late this afternoon and evening. ...Ohio Valley/Central Appalachians to the Tennessee Valley... A large-scale upper trough/low will remain centered over Ontario today, with mid/upper-level troughing extending southward across much of the Great Lakes/Midwest into the OH Valley. A cold front will continue to advance slowly southeastward across portions of the Mid-South and OH Valley through this evening. Daytime heating of a seasonably moist low-level airmass ahead of this front over the TN Valley will likely yield upwards of 1500-2500 J/kg MLCAPE by late afternoon, mainly in KY/TN. Weaker instability is forecast with northward extent into the upper OH Valley and central Appalachians. Forcing for ascent aloft will remain nebulous for much of the day, with generally neutral mid-level heights and stronger flow remaining confined to the north of the surface cold front. Still, a subtle mid-level perturbation over eastern KS and the Ozarks late this morning should continue eastward towards the Mid-South and lower OH Valley by late afternoon/early evening. This feature, along with modest low-level convergence along the front, may be sufficient to encourage initial convective development by 21-23Z across parts of KY/TN. Even with stronger flow aloft remaining displaced to the north of the surface warm sector, some veering and gradual strengthening with height through mid/upper levels should support sufficient deep-layer shear for updraft organization. Current expectations are for multiple clusters to develop and pose a risk for mainly severe/damaging winds as they spread eastward across the TN and upper OH Valleys through the late afternoon and evening. With cool temperatures aloft and marginal deep-layer shear to support supercells, some of this activity could also pose a threat for isolated hail, especially any cells that can remain at least semi-discrete. A brief tornado or two also appears possible, although low-level shear should remain fairly limited given veered/west-southwesterly low-level flow. With a relatively narrow warm sector expected, convection should generally weaken this evening as it moves into the higher terrain of the central Appalachians and encounters a less unstable airmass. ...Mid-South to North Texas... An elongated mid-level thermal trough, characterized by 500 mb temperatures around -8 to -12 C per RAP analysis and 12Z OUN/FWD observed soundings, extends into much of OK and north TX, well to the south of the vertically stacked cyclone over Ontario. Low to mid-level flow should remain modest across this region, with some signal from various NAM/RAP forecast soundings of a veer-back-veer signature. Strong speed shear should remain confined above 500 mb, coincident with poor upper-level lapse rates atop steeper mid-level lapse rates. This suggests a messy convective mode should be common as convection increases in the late afternoon and evening, along the more west/east-oriented portion of the surface cold front. Have maintained the Marginal Risk for an isolated severe hail/wind threat with a small westward expansion with this update. ...Oregon... Isolated to scattered thunderstorms should develop today across parts of OR as a weak mid-level trough moves northward across the Pacific Northwest Coast. While low/mid-level flow is expected to remain rather modest, steepened low-level lapse rates could support isolated strong/gusty winds with any high-based convection that develops this afternoon/evening. ..Gleason/Weinman.. 09/05/2025 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1131 AM CDT Fri Sep 05 2025 Valid 051700Z - 061200Z ...Update... No changes were required for today's forecast. Expect increasing chances of lightning beginning late this afternoon across southeastern OR, peaking by this evening over central OR. ..Barnes.. 09/05/2025 .PREV DISCUSSION... /ISSUED 0137 AM CDT Fri Sep 05 2025/ ...Synopsis... A mid-level trough will traverse the Midwest/Great Lakes Regions as upper ridging remains in place over the Interior West, but with a small but pronounced mid-level impulse impinging on the northern California coastline today. This impulse, in tandem with adequate instability, will provide enough lift to support at least scattered thunderstorms to portions of the Pacific Northwest this afternoon into the overnight hours. These storms will move atop a modestly dry boundary layer, with wet and dry storm modes both possible. Nonetheless, these storms will overspread dry fuel beds, especially from the central/northern Cascades and points east. Dry thunderstorm highlights remain in place for the possibility of lightning strikes (some dry) posing a hazard for fuel ignition. ...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 1131 AM CDT Fri Sep 05 2025 Valid 051700Z - 061200Z ...Update... No changes were required for today's forecast. Expect increasing chances of lightning beginning late this afternoon across southeastern OR, peaking by this evening over central OR. ..Barnes.. 09/05/2025 .PREV DISCUSSION... /ISSUED 0137 AM CDT Fri Sep 05 2025/ ...Synopsis... A mid-level trough will traverse the Midwest/Great Lakes Regions as upper ridging remains in place over the Interior West, but with a small but pronounced mid-level impulse impinging on the northern California coastline today. This impulse, in tandem with adequate instability, will provide enough lift to support at least scattered thunderstorms to portions of the Pacific Northwest this afternoon into the overnight hours. These storms will move atop a modestly dry boundary layer, with wet and dry storm modes both possible. Nonetheless, these storms will overspread dry fuel beds, especially from the central/northern Cascades and points east. Dry thunderstorm highlights remain in place for the possibility of lightning strikes (some dry) posing a hazard for fuel ignition. ...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 1131 AM CDT Fri Sep 05 2025 Valid 051700Z - 061200Z ...Update... No changes were required for today's forecast. Expect increasing chances of lightning beginning late this afternoon across southeastern OR, peaking by this evening over central OR. ..Barnes.. 09/05/2025 .PREV DISCUSSION... /ISSUED 0137 AM CDT Fri Sep 05 2025/ ...Synopsis... A mid-level trough will traverse the Midwest/Great Lakes Regions as upper ridging remains in place over the Interior West, but with a small but pronounced mid-level impulse impinging on the northern California coastline today. This impulse, in tandem with adequate instability, will provide enough lift to support at least scattered thunderstorms to portions of the Pacific Northwest this afternoon into the overnight hours. These storms will move atop a modestly dry boundary layer, with wet and dry storm modes both possible. Nonetheless, these storms will overspread dry fuel beds, especially from the central/northern Cascades and points east. Dry thunderstorm highlights remain in place for the possibility of lightning strikes (some dry) posing a hazard for fuel ignition. ...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 1131 AM CDT Fri Sep 05 2025 Valid 051700Z - 061200Z ...Update... No changes were required for today's forecast. Expect increasing chances of lightning beginning late this afternoon across southeastern OR, peaking by this evening over central OR. ..Barnes.. 09/05/2025 .PREV DISCUSSION... /ISSUED 0137 AM CDT Fri Sep 05 2025/ ...Synopsis... A mid-level trough will traverse the Midwest/Great Lakes Regions as upper ridging remains in place over the Interior West, but with a small but pronounced mid-level impulse impinging on the northern California coastline today. This impulse, in tandem with adequate instability, will provide enough lift to support at least scattered thunderstorms to portions of the Pacific Northwest this afternoon into the overnight hours. These storms will move atop a modestly dry boundary layer, with wet and dry storm modes both possible. Nonetheless, these storms will overspread dry fuel beds, especially from the central/northern Cascades and points east. Dry thunderstorm highlights remain in place for the possibility of lightning strikes (some dry) posing a hazard for fuel ignition. ...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 1131 AM CDT Fri Sep 05 2025 Valid 051700Z - 061200Z ...Update... No changes were required for today's forecast. Expect increasing chances of lightning beginning late this afternoon across southeastern OR, peaking by this evening over central OR. ..Barnes.. 09/05/2025 .PREV DISCUSSION... /ISSUED 0137 AM CDT Fri Sep 05 2025/ ...Synopsis... A mid-level trough will traverse the Midwest/Great Lakes Regions as upper ridging remains in place over the Interior West, but with a small but pronounced mid-level impulse impinging on the northern California coastline today. This impulse, in tandem with adequate instability, will provide enough lift to support at least scattered thunderstorms to portions of the Pacific Northwest this afternoon into the overnight hours. These storms will move atop a modestly dry boundary layer, with wet and dry storm modes both possible. Nonetheless, these storms will overspread dry fuel beds, especially from the central/northern Cascades and points east. Dry thunderstorm highlights remain in place for the possibility of lightning strikes (some dry) posing a hazard for fuel ignition. ...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 1131 AM CDT Fri Sep 05 2025 Valid 051700Z - 061200Z ...Update... No changes were required for today's forecast. Expect increasing chances of lightning beginning late this afternoon across southeastern OR, peaking by this evening over central OR. ..Barnes.. 09/05/2025 .PREV DISCUSSION... /ISSUED 0137 AM CDT Fri Sep 05 2025/ ...Synopsis... A mid-level trough will traverse the Midwest/Great Lakes Regions as upper ridging remains in place over the Interior West, but with a small but pronounced mid-level impulse impinging on the northern California coastline today. This impulse, in tandem with adequate instability, will provide enough lift to support at least scattered thunderstorms to portions of the Pacific Northwest this afternoon into the overnight hours. These storms will move atop a modestly dry boundary layer, with wet and dry storm modes both possible. Nonetheless, these storms will overspread dry fuel beds, especially from the central/northern Cascades and points east. Dry thunderstorm highlights remain in place for the possibility of lightning strikes (some dry) posing a hazard for fuel ignition. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0709 AM CDT Fri Sep 05 2025 Valid 051300Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE TENNESSEE VALLEY AND UPPER OHIO VALLEY... ...SUMMARY... Scattered damaging winds, isolated severe hail, and a brief tornado or two are possible from the Upper Ohio to Tennessee Valleys during the late afternoon and evening. ...Upper OH to TN Valleys... Water-vapor imagery shows a large gyre centered over Ontario and cyclonic flow over much of eastern North America. A series of mid-level disturbances/speed maxima will rotate through its base during the Day-1 period, and there are two lead impulses over the St. Lawrence Seaway and the Upper Great Lakes this morning. A weaker impulse associated with convection early this morning over KS will rapidly move east into the northern part of the OH Valley through this evening and immediately ahead of a more notable shortwave trough moving southeast from the Dakotas into the Great Lakes. A cold front oriented mostly north-south over the Great Lakes from a surface low will push east during the day, while the trailing southern portion of the boundary that is west-east oriented, gradually pushes south and eventually overtakes a residual frontal segment. Heating ahead of the aforementioned low-amplitude impulse and strengthening low-level convergence along the boundary will likely yield scattered to numerous showers/thunderstorms developing in the late afternoon to early evening. Much of the stronger mid-level flow will remain spatially displaced from the warm sector in the post-frontal airmass except over the Upper OH Valley. Moderate buoyancy will favor strong to severe multicells and some supercells (where shear is stronger). Isolated severe gusts (55-70 mph) seem probable which will result in scattered wind damage accompanying the stronger thunderstorm cores and line segments. Models differ on the character of mixing and hodograph size over the southeast OH/WV portion of the Slight Risk, but low-tornado potential may be greatest here compared to farther south/southwest over the TN Valley. The severe threat will diminish towards late evening given the extensive overturning and lack of stronger low-level flow/shear to sustain the threat overnight. ...North TX to Mid-South... An elongated mid-level thermal trough, characterized by 500-mb temperatures of -10 to -12 C, will extend into north TX, well to the south of a persistent vertically stacked cyclone over northern Ontario. A copious amount of high cloud cover will tend to result in high-level lapse rates becoming weaker during the period. Model data implies a messy storm mode as isolated to locally scattered storm coverage ensues during the late afternoon/evening. An isolated wind/hail risk may accompany the stronger storms. ..Smith/Broyles.. 09/05/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0709 AM CDT Fri Sep 05 2025 Valid 051300Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE TENNESSEE VALLEY AND UPPER OHIO VALLEY... ...SUMMARY... Scattered damaging winds, isolated severe hail, and a brief tornado or two are possible from the Upper Ohio to Tennessee Valleys during the late afternoon and evening. ...Upper OH to TN Valleys... Water-vapor imagery shows a large gyre centered over Ontario and cyclonic flow over much of eastern North America. A series of mid-level disturbances/speed maxima will rotate through its base during the Day-1 period, and there are two lead impulses over the St. Lawrence Seaway and the Upper Great Lakes this morning. A weaker impulse associated with convection early this morning over KS will rapidly move east into the northern part of the OH Valley through this evening and immediately ahead of a more notable shortwave trough moving southeast from the Dakotas into the Great Lakes. A cold front oriented mostly north-south over the Great Lakes from a surface low will push east during the day, while the trailing southern portion of the boundary that is west-east oriented, gradually pushes south and eventually overtakes a residual frontal segment. Heating ahead of the aforementioned low-amplitude impulse and strengthening low-level convergence along the boundary will likely yield scattered to numerous showers/thunderstorms developing in the late afternoon to early evening. Much of the stronger mid-level flow will remain spatially displaced from the warm sector in the post-frontal airmass except over the Upper OH Valley. Moderate buoyancy will favor strong to severe multicells and some supercells (where shear is stronger). Isolated severe gusts (55-70 mph) seem probable which will result in scattered wind damage accompanying the stronger thunderstorm cores and line segments. Models differ on the character of mixing and hodograph size over the southeast OH/WV portion of the Slight Risk, but low-tornado potential may be greatest here compared to farther south/southwest over the TN Valley. The severe threat will diminish towards late evening given the extensive overturning and lack of stronger low-level flow/shear to sustain the threat overnight. ...North TX to Mid-South... An elongated mid-level thermal trough, characterized by 500-mb temperatures of -10 to -12 C, will extend into north TX, well to the south of a persistent vertically stacked cyclone over northern Ontario. A copious amount of high cloud cover will tend to result in high-level lapse rates becoming weaker during the period. Model data implies a messy storm mode as isolated to locally scattered storm coverage ensues during the late afternoon/evening. An isolated wind/hail risk may accompany the stronger storms. ..Smith/Broyles.. 09/05/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0709 AM CDT Fri Sep 05 2025 Valid 051300Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE TENNESSEE VALLEY AND UPPER OHIO VALLEY... ...SUMMARY... Scattered damaging winds, isolated severe hail, and a brief tornado or two are possible from the Upper Ohio to Tennessee Valleys during the late afternoon and evening. ...Upper OH to TN Valleys... Water-vapor imagery shows a large gyre centered over Ontario and cyclonic flow over much of eastern North America. A series of mid-level disturbances/speed maxima will rotate through its base during the Day-1 period, and there are two lead impulses over the St. Lawrence Seaway and the Upper Great Lakes this morning. A weaker impulse associated with convection early this morning over KS will rapidly move east into the northern part of the OH Valley through this evening and immediately ahead of a more notable shortwave trough moving southeast from the Dakotas into the Great Lakes. A cold front oriented mostly north-south over the Great Lakes from a surface low will push east during the day, while the trailing southern portion of the boundary that is west-east oriented, gradually pushes south and eventually overtakes a residual frontal segment. Heating ahead of the aforementioned low-amplitude impulse and strengthening low-level convergence along the boundary will likely yield scattered to numerous showers/thunderstorms developing in the late afternoon to early evening. Much of the stronger mid-level flow will remain spatially displaced from the warm sector in the post-frontal airmass except over the Upper OH Valley. Moderate buoyancy will favor strong to severe multicells and some supercells (where shear is stronger). Isolated severe gusts (55-70 mph) seem probable which will result in scattered wind damage accompanying the stronger thunderstorm cores and line segments. Models differ on the character of mixing and hodograph size over the southeast OH/WV portion of the Slight Risk, but low-tornado potential may be greatest here compared to farther south/southwest over the TN Valley. The severe threat will diminish towards late evening given the extensive overturning and lack of stronger low-level flow/shear to sustain the threat overnight. ...North TX to Mid-South... An elongated mid-level thermal trough, characterized by 500-mb temperatures of -10 to -12 C, will extend into north TX, well to the south of a persistent vertically stacked cyclone over northern Ontario. A copious amount of high cloud cover will tend to result in high-level lapse rates becoming weaker during the period. Model data implies a messy storm mode as isolated to locally scattered storm coverage ensues during the late afternoon/evening. An isolated wind/hail risk may accompany the stronger storms. ..Smith/Broyles.. 09/05/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0709 AM CDT Fri Sep 05 2025 Valid 051300Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE TENNESSEE VALLEY AND UPPER OHIO VALLEY... ...SUMMARY... Scattered damaging winds, isolated severe hail, and a brief tornado or two are possible from the Upper Ohio to Tennessee Valleys during the late afternoon and evening. ...Upper OH to TN Valleys... Water-vapor imagery shows a large gyre centered over Ontario and cyclonic flow over much of eastern North America. A series of mid-level disturbances/speed maxima will rotate through its base during the Day-1 period, and there are two lead impulses over the St. Lawrence Seaway and the Upper Great Lakes this morning. A weaker impulse associated with convection early this morning over KS will rapidly move east into the northern part of the OH Valley through this evening and immediately ahead of a more notable shortwave trough moving southeast from the Dakotas into the Great Lakes. A cold front oriented mostly north-south over the Great Lakes from a surface low will push east during the day, while the trailing southern portion of the boundary that is west-east oriented, gradually pushes south and eventually overtakes a residual frontal segment. Heating ahead of the aforementioned low-amplitude impulse and strengthening low-level convergence along the boundary will likely yield scattered to numerous showers/thunderstorms developing in the late afternoon to early evening. Much of the stronger mid-level flow will remain spatially displaced from the warm sector in the post-frontal airmass except over the Upper OH Valley. Moderate buoyancy will favor strong to severe multicells and some supercells (where shear is stronger). Isolated severe gusts (55-70 mph) seem probable which will result in scattered wind damage accompanying the stronger thunderstorm cores and line segments. Models differ on the character of mixing and hodograph size over the southeast OH/WV portion of the Slight Risk, but low-tornado potential may be greatest here compared to farther south/southwest over the TN Valley. The severe threat will diminish towards late evening given the extensive overturning and lack of stronger low-level flow/shear to sustain the threat overnight. ...North TX to Mid-South... An elongated mid-level thermal trough, characterized by 500-mb temperatures of -10 to -12 C, will extend into north TX, well to the south of a persistent vertically stacked cyclone over northern Ontario. A copious amount of high cloud cover will tend to result in high-level lapse rates becoming weaker during the period. Model data implies a messy storm mode as isolated to locally scattered storm coverage ensues during the late afternoon/evening. An isolated wind/hail risk may accompany the stronger storms. ..Smith/Broyles.. 09/05/2025 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0354 AM CDT Fri Sep 05 2025 Valid 081200Z - 131200Z ...DISCUSSION... Upper-level ridging within the West will slowly shift into the Plains this weekend and into perhaps the middle of next week. Modest to moderate mid-level flow will generally continue across the Midwest/Northeast. In the West, current guidance shows a trough slowly making progress east next week. Model guidance has shown a high degree of variability with regard to how this western trough will evolve through time. Expansive surface high pressure will be present in parts of the Plains and points eastward. With time, this high will move east and promote southerly return flow across the Plains. This process will accelerate as the western trough approaches. While some strong to severe storms will be possible as moisture returns northward, the timing and location of this potential largely depends on where surface boundaries set up and where smaller scale perturbations will eject into the Plains. The predictability of these features remains low at this time. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0354 AM CDT Fri Sep 05 2025 Valid 081200Z - 131200Z ...DISCUSSION... Upper-level ridging within the West will slowly shift into the Plains this weekend and into perhaps the middle of next week. Modest to moderate mid-level flow will generally continue across the Midwest/Northeast. In the West, current guidance shows a trough slowly making progress east next week. Model guidance has shown a high degree of variability with regard to how this western trough will evolve through time. Expansive surface high pressure will be present in parts of the Plains and points eastward. With time, this high will move east and promote southerly return flow across the Plains. This process will accelerate as the western trough approaches. While some strong to severe storms will be possible as moisture returns northward, the timing and location of this potential largely depends on where surface boundaries set up and where smaller scale perturbations will eject into the Plains. The predictability of these features remains low at this time. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0354 AM CDT Fri Sep 05 2025 Valid 081200Z - 131200Z ...DISCUSSION... Upper-level ridging within the West will slowly shift into the Plains this weekend and into perhaps the middle of next week. Modest to moderate mid-level flow will generally continue across the Midwest/Northeast. In the West, current guidance shows a trough slowly making progress east next week. Model guidance has shown a high degree of variability with regard to how this western trough will evolve through time. Expansive surface high pressure will be present in parts of the Plains and points eastward. With time, this high will move east and promote southerly return flow across the Plains. This process will accelerate as the western trough approaches. While some strong to severe storms will be possible as moisture returns northward, the timing and location of this potential largely depends on where surface boundaries set up and where smaller scale perturbations will eject into the Plains. The predictability of these features remains low at this time. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0354 AM CDT Fri Sep 05 2025 Valid 081200Z - 131200Z ...DISCUSSION... Upper-level ridging within the West will slowly shift into the Plains this weekend and into perhaps the middle of next week. Modest to moderate mid-level flow will generally continue across the Midwest/Northeast. In the West, current guidance shows a trough slowly making progress east next week. Model guidance has shown a high degree of variability with regard to how this western trough will evolve through time. Expansive surface high pressure will be present in parts of the Plains and points eastward. With time, this high will move east and promote southerly return flow across the Plains. This process will accelerate as the western trough approaches. While some strong to severe storms will be possible as moisture returns northward, the timing and location of this potential largely depends on where surface boundaries set up and where smaller scale perturbations will eject into the Plains. The predictability of these features remains low at this time. Read more