Severe Storms

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0229 PM CDT Thu Sep 04 2025 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE MID-ATLANTIC INTO THE NORTHEAST... ...SUMMARY... Widely scattered thunderstorms will pose a risk of damaging wind gusts across parts of the Mid-Atlantic into the Northeast on Saturday. ...Synopsis... A broad/amplified mid/upper-level trough encompassing much of the eastern CONUS will shift slightly eastward through the forecast period, while an accompanying strong upper-level jet advances northeastward across Quebec. In the low-levels, a related north-south-oriented cold front will move eastward across the Northeast and Mid-Atlantic region through the afternoon. ...Northeast into the Mid-Atlantic... Ahead of the eastward-moving cold front, diurnal heating/ destabilization of a moist boundary layer (middle/upper 60s to lower 70s dewpoints) will contribute to a corridor of moderate surface-based buoyancy (1000-2000 J/kg MLCAPE) from the Mid-Atlantic into the Northeast -- despite poor midlevel lapse rates. Diurnal heating and related buoyancy may be limited with northward extent owing to increased cloud coverage near the right-entrance region of the upper-level jet. As the front intercepts the destabilizing/uncapped pre-convective air mass, widely scattered thunderstorms should develop along/immediately ahead of the front during the afternoon. Around 35-45 kt of front-parallel effective shear will support a mix of loosely organized convective bands and clusters. Given the enhanced deep-layer unidirectional flow and steepening low-level lapse rates, damaging wind gusts will be possible with the stronger storms into the evening. Depending on the degree of destabilization over parts of the Mid-Atlantic into the Northeast, an eventual upgrade may be warranted. ..Weinman.. 09/04/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0229 PM CDT Thu Sep 04 2025 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE MID-ATLANTIC INTO THE NORTHEAST... ...SUMMARY... Widely scattered thunderstorms will pose a risk of damaging wind gusts across parts of the Mid-Atlantic into the Northeast on Saturday. ...Synopsis... A broad/amplified mid/upper-level trough encompassing much of the eastern CONUS will shift slightly eastward through the forecast period, while an accompanying strong upper-level jet advances northeastward across Quebec. In the low-levels, a related north-south-oriented cold front will move eastward across the Northeast and Mid-Atlantic region through the afternoon. ...Northeast into the Mid-Atlantic... Ahead of the eastward-moving cold front, diurnal heating/ destabilization of a moist boundary layer (middle/upper 60s to lower 70s dewpoints) will contribute to a corridor of moderate surface-based buoyancy (1000-2000 J/kg MLCAPE) from the Mid-Atlantic into the Northeast -- despite poor midlevel lapse rates. Diurnal heating and related buoyancy may be limited with northward extent owing to increased cloud coverage near the right-entrance region of the upper-level jet. As the front intercepts the destabilizing/uncapped pre-convective air mass, widely scattered thunderstorms should develop along/immediately ahead of the front during the afternoon. Around 35-45 kt of front-parallel effective shear will support a mix of loosely organized convective bands and clusters. Given the enhanced deep-layer unidirectional flow and steepening low-level lapse rates, damaging wind gusts will be possible with the stronger storms into the evening. Depending on the degree of destabilization over parts of the Mid-Atlantic into the Northeast, an eventual upgrade may be warranted. ..Weinman.. 09/04/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0229 PM CDT Thu Sep 04 2025 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE MID-ATLANTIC INTO THE NORTHEAST... ...SUMMARY... Widely scattered thunderstorms will pose a risk of damaging wind gusts across parts of the Mid-Atlantic into the Northeast on Saturday. ...Synopsis... A broad/amplified mid/upper-level trough encompassing much of the eastern CONUS will shift slightly eastward through the forecast period, while an accompanying strong upper-level jet advances northeastward across Quebec. In the low-levels, a related north-south-oriented cold front will move eastward across the Northeast and Mid-Atlantic region through the afternoon. ...Northeast into the Mid-Atlantic... Ahead of the eastward-moving cold front, diurnal heating/ destabilization of a moist boundary layer (middle/upper 60s to lower 70s dewpoints) will contribute to a corridor of moderate surface-based buoyancy (1000-2000 J/kg MLCAPE) from the Mid-Atlantic into the Northeast -- despite poor midlevel lapse rates. Diurnal heating and related buoyancy may be limited with northward extent owing to increased cloud coverage near the right-entrance region of the upper-level jet. As the front intercepts the destabilizing/uncapped pre-convective air mass, widely scattered thunderstorms should develop along/immediately ahead of the front during the afternoon. Around 35-45 kt of front-parallel effective shear will support a mix of loosely organized convective bands and clusters. Given the enhanced deep-layer unidirectional flow and steepening low-level lapse rates, damaging wind gusts will be possible with the stronger storms into the evening. Depending on the degree of destabilization over parts of the Mid-Atlantic into the Northeast, an eventual upgrade may be warranted. ..Weinman.. 09/04/2025 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0208 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z A rather expansive IsoDryT area was added as scattered to widespread mixed wet/dry thunderstorms are expected across central Oregon/vicinity tomorrow with more isolated coverage into western Oregon and western/central Washington. Late evening and nocturnal thunderstorms are possible in portions of central/eastern/northwest Oregon and western Washington. While wetting rain is likely in portions of central/eastern Oregon, the amount of lightning and dry to very dry fuels as evident by new ignitions and active to extreme fire behavior on large fires in the region support the introduction of an IsoDryT area. Storms will track generally northward at 10-20 knots likely producing abundant lightning, including outside of the cores, with drier air moving into portions of southern/central Oregon behind them. Precipitable water values will range from 0.7-1.3" in the IsoDryT area and training of storms with some of those higher PWAT values will lead to wetting rain in areas. The onshore flow/marine layer is also precluding including more of coastal Oregon in the IsoDryT area as it looks to deepen tomorrow, but thunderstorms may go up the Coast Ranges late tomorrow. Deep pyroconvection remains possible on very active large wildfires in the Northwest, north Idaho, and California. A complicating factor in this forecast is the quantity of smoke that will be in the region from existing fires and being transported southward from Canada. ..Nauslar.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1249 AM CDT Thu Sep 04 2025/ ...Synopsis... A secondary mid-level wave will traverse the Pacific Northwest on D2/Friday. This wave will bring much cooler temperatures, higher relative humidity, and potential for more widespread thunderstorm activity. While lightning efficiency may increase, increase coverage of thunderstorms and better organization with increasing shear should promote heavier cores and wetting rainfall potential. As such, no isolated thunderstorm areas were included at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0208 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z A rather expansive IsoDryT area was added as scattered to widespread mixed wet/dry thunderstorms are expected across central Oregon/vicinity tomorrow with more isolated coverage into western Oregon and western/central Washington. Late evening and nocturnal thunderstorms are possible in portions of central/eastern/northwest Oregon and western Washington. While wetting rain is likely in portions of central/eastern Oregon, the amount of lightning and dry to very dry fuels as evident by new ignitions and active to extreme fire behavior on large fires in the region support the introduction of an IsoDryT area. Storms will track generally northward at 10-20 knots likely producing abundant lightning, including outside of the cores, with drier air moving into portions of southern/central Oregon behind them. Precipitable water values will range from 0.7-1.3" in the IsoDryT area and training of storms with some of those higher PWAT values will lead to wetting rain in areas. The onshore flow/marine layer is also precluding including more of coastal Oregon in the IsoDryT area as it looks to deepen tomorrow, but thunderstorms may go up the Coast Ranges late tomorrow. Deep pyroconvection remains possible on very active large wildfires in the Northwest, north Idaho, and California. A complicating factor in this forecast is the quantity of smoke that will be in the region from existing fires and being transported southward from Canada. ..Nauslar.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1249 AM CDT Thu Sep 04 2025/ ...Synopsis... A secondary mid-level wave will traverse the Pacific Northwest on D2/Friday. This wave will bring much cooler temperatures, higher relative humidity, and potential for more widespread thunderstorm activity. While lightning efficiency may increase, increase coverage of thunderstorms and better organization with increasing shear should promote heavier cores and wetting rainfall potential. As such, no isolated thunderstorm areas were included at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0208 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z A rather expansive IsoDryT area was added as scattered to widespread mixed wet/dry thunderstorms are expected across central Oregon/vicinity tomorrow with more isolated coverage into western Oregon and western/central Washington. Late evening and nocturnal thunderstorms are possible in portions of central/eastern/northwest Oregon and western Washington. While wetting rain is likely in portions of central/eastern Oregon, the amount of lightning and dry to very dry fuels as evident by new ignitions and active to extreme fire behavior on large fires in the region support the introduction of an IsoDryT area. Storms will track generally northward at 10-20 knots likely producing abundant lightning, including outside of the cores, with drier air moving into portions of southern/central Oregon behind them. Precipitable water values will range from 0.7-1.3" in the IsoDryT area and training of storms with some of those higher PWAT values will lead to wetting rain in areas. The onshore flow/marine layer is also precluding including more of coastal Oregon in the IsoDryT area as it looks to deepen tomorrow, but thunderstorms may go up the Coast Ranges late tomorrow. Deep pyroconvection remains possible on very active large wildfires in the Northwest, north Idaho, and California. A complicating factor in this forecast is the quantity of smoke that will be in the region from existing fires and being transported southward from Canada. ..Nauslar.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1249 AM CDT Thu Sep 04 2025/ ...Synopsis... A secondary mid-level wave will traverse the Pacific Northwest on D2/Friday. This wave will bring much cooler temperatures, higher relative humidity, and potential for more widespread thunderstorm activity. While lightning efficiency may increase, increase coverage of thunderstorms and better organization with increasing shear should promote heavier cores and wetting rainfall potential. As such, no isolated thunderstorm areas were included at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0208 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z A rather expansive IsoDryT area was added as scattered to widespread mixed wet/dry thunderstorms are expected across central Oregon/vicinity tomorrow with more isolated coverage into western Oregon and western/central Washington. Late evening and nocturnal thunderstorms are possible in portions of central/eastern/northwest Oregon and western Washington. While wetting rain is likely in portions of central/eastern Oregon, the amount of lightning and dry to very dry fuels as evident by new ignitions and active to extreme fire behavior on large fires in the region support the introduction of an IsoDryT area. Storms will track generally northward at 10-20 knots likely producing abundant lightning, including outside of the cores, with drier air moving into portions of southern/central Oregon behind them. Precipitable water values will range from 0.7-1.3" in the IsoDryT area and training of storms with some of those higher PWAT values will lead to wetting rain in areas. The onshore flow/marine layer is also precluding including more of coastal Oregon in the IsoDryT area as it looks to deepen tomorrow, but thunderstorms may go up the Coast Ranges late tomorrow. Deep pyroconvection remains possible on very active large wildfires in the Northwest, north Idaho, and California. A complicating factor in this forecast is the quantity of smoke that will be in the region from existing fires and being transported southward from Canada. ..Nauslar.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1249 AM CDT Thu Sep 04 2025/ ...Synopsis... A secondary mid-level wave will traverse the Pacific Northwest on D2/Friday. This wave will bring much cooler temperatures, higher relative humidity, and potential for more widespread thunderstorm activity. While lightning efficiency may increase, increase coverage of thunderstorms and better organization with increasing shear should promote heavier cores and wetting rainfall potential. As such, no isolated thunderstorm areas were included at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0208 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z A rather expansive IsoDryT area was added as scattered to widespread mixed wet/dry thunderstorms are expected across central Oregon/vicinity tomorrow with more isolated coverage into western Oregon and western/central Washington. Late evening and nocturnal thunderstorms are possible in portions of central/eastern/northwest Oregon and western Washington. While wetting rain is likely in portions of central/eastern Oregon, the amount of lightning and dry to very dry fuels as evident by new ignitions and active to extreme fire behavior on large fires in the region support the introduction of an IsoDryT area. Storms will track generally northward at 10-20 knots likely producing abundant lightning, including outside of the cores, with drier air moving into portions of southern/central Oregon behind them. Precipitable water values will range from 0.7-1.3" in the IsoDryT area and training of storms with some of those higher PWAT values will lead to wetting rain in areas. The onshore flow/marine layer is also precluding including more of coastal Oregon in the IsoDryT area as it looks to deepen tomorrow, but thunderstorms may go up the Coast Ranges late tomorrow. Deep pyroconvection remains possible on very active large wildfires in the Northwest, north Idaho, and California. A complicating factor in this forecast is the quantity of smoke that will be in the region from existing fires and being transported southward from Canada. ..Nauslar.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1249 AM CDT Thu Sep 04 2025/ ...Synopsis... A secondary mid-level wave will traverse the Pacific Northwest on D2/Friday. This wave will bring much cooler temperatures, higher relative humidity, and potential for more widespread thunderstorm activity. While lightning efficiency may increase, increase coverage of thunderstorms and better organization with increasing shear should promote heavier cores and wetting rainfall potential. As such, no isolated thunderstorm areas were included at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0208 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z A rather expansive IsoDryT area was added as scattered to widespread mixed wet/dry thunderstorms are expected across central Oregon/vicinity tomorrow with more isolated coverage into western Oregon and western/central Washington. Late evening and nocturnal thunderstorms are possible in portions of central/eastern/northwest Oregon and western Washington. While wetting rain is likely in portions of central/eastern Oregon, the amount of lightning and dry to very dry fuels as evident by new ignitions and active to extreme fire behavior on large fires in the region support the introduction of an IsoDryT area. Storms will track generally northward at 10-20 knots likely producing abundant lightning, including outside of the cores, with drier air moving into portions of southern/central Oregon behind them. Precipitable water values will range from 0.7-1.3" in the IsoDryT area and training of storms with some of those higher PWAT values will lead to wetting rain in areas. The onshore flow/marine layer is also precluding including more of coastal Oregon in the IsoDryT area as it looks to deepen tomorrow, but thunderstorms may go up the Coast Ranges late tomorrow. Deep pyroconvection remains possible on very active large wildfires in the Northwest, north Idaho, and California. A complicating factor in this forecast is the quantity of smoke that will be in the region from existing fires and being transported southward from Canada. ..Nauslar.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1249 AM CDT Thu Sep 04 2025/ ...Synopsis... A secondary mid-level wave will traverse the Pacific Northwest on D2/Friday. This wave will bring much cooler temperatures, higher relative humidity, and potential for more widespread thunderstorm activity. While lightning efficiency may increase, increase coverage of thunderstorms and better organization with increasing shear should promote heavier cores and wetting rainfall potential. As such, no isolated thunderstorm areas were included at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0208 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z A rather expansive IsoDryT area was added as scattered to widespread mixed wet/dry thunderstorms are expected across central Oregon/vicinity tomorrow with more isolated coverage into western Oregon and western/central Washington. Late evening and nocturnal thunderstorms are possible in portions of central/eastern/northwest Oregon and western Washington. While wetting rain is likely in portions of central/eastern Oregon, the amount of lightning and dry to very dry fuels as evident by new ignitions and active to extreme fire behavior on large fires in the region support the introduction of an IsoDryT area. Storms will track generally northward at 10-20 knots likely producing abundant lightning, including outside of the cores, with drier air moving into portions of southern/central Oregon behind them. Precipitable water values will range from 0.7-1.3" in the IsoDryT area and training of storms with some of those higher PWAT values will lead to wetting rain in areas. The onshore flow/marine layer is also precluding including more of coastal Oregon in the IsoDryT area as it looks to deepen tomorrow, but thunderstorms may go up the Coast Ranges late tomorrow. Deep pyroconvection remains possible on very active large wildfires in the Northwest, north Idaho, and California. A complicating factor in this forecast is the quantity of smoke that will be in the region from existing fires and being transported southward from Canada. ..Nauslar.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1249 AM CDT Thu Sep 04 2025/ ...Synopsis... A secondary mid-level wave will traverse the Pacific Northwest on D2/Friday. This wave will bring much cooler temperatures, higher relative humidity, and potential for more widespread thunderstorm activity. While lightning efficiency may increase, increase coverage of thunderstorms and better organization with increasing shear should promote heavier cores and wetting rainfall potential. As such, no isolated thunderstorm areas were included at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0208 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z A rather expansive IsoDryT area was added as scattered to widespread mixed wet/dry thunderstorms are expected across central Oregon/vicinity tomorrow with more isolated coverage into western Oregon and western/central Washington. Late evening and nocturnal thunderstorms are possible in portions of central/eastern/northwest Oregon and western Washington. While wetting rain is likely in portions of central/eastern Oregon, the amount of lightning and dry to very dry fuels as evident by new ignitions and active to extreme fire behavior on large fires in the region support the introduction of an IsoDryT area. Storms will track generally northward at 10-20 knots likely producing abundant lightning, including outside of the cores, with drier air moving into portions of southern/central Oregon behind them. Precipitable water values will range from 0.7-1.3" in the IsoDryT area and training of storms with some of those higher PWAT values will lead to wetting rain in areas. The onshore flow/marine layer is also precluding including more of coastal Oregon in the IsoDryT area as it looks to deepen tomorrow, but thunderstorms may go up the Coast Ranges late tomorrow. Deep pyroconvection remains possible on very active large wildfires in the Northwest, north Idaho, and California. A complicating factor in this forecast is the quantity of smoke that will be in the region from existing fires and being transported southward from Canada. ..Nauslar.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1249 AM CDT Thu Sep 04 2025/ ...Synopsis... A secondary mid-level wave will traverse the Pacific Northwest on D2/Friday. This wave will bring much cooler temperatures, higher relative humidity, and potential for more widespread thunderstorm activity. While lightning efficiency may increase, increase coverage of thunderstorms and better organization with increasing shear should promote heavier cores and wetting rainfall potential. As such, no isolated thunderstorm areas were included at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0208 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z A rather expansive IsoDryT area was added as scattered to widespread mixed wet/dry thunderstorms are expected across central Oregon/vicinity tomorrow with more isolated coverage into western Oregon and western/central Washington. Late evening and nocturnal thunderstorms are possible in portions of central/eastern/northwest Oregon and western Washington. While wetting rain is likely in portions of central/eastern Oregon, the amount of lightning and dry to very dry fuels as evident by new ignitions and active to extreme fire behavior on large fires in the region support the introduction of an IsoDryT area. Storms will track generally northward at 10-20 knots likely producing abundant lightning, including outside of the cores, with drier air moving into portions of southern/central Oregon behind them. Precipitable water values will range from 0.7-1.3" in the IsoDryT area and training of storms with some of those higher PWAT values will lead to wetting rain in areas. The onshore flow/marine layer is also precluding including more of coastal Oregon in the IsoDryT area as it looks to deepen tomorrow, but thunderstorms may go up the Coast Ranges late tomorrow. Deep pyroconvection remains possible on very active large wildfires in the Northwest, north Idaho, and California. A complicating factor in this forecast is the quantity of smoke that will be in the region from existing fires and being transported southward from Canada. ..Nauslar.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1249 AM CDT Thu Sep 04 2025/ ...Synopsis... A secondary mid-level wave will traverse the Pacific Northwest on D2/Friday. This wave will bring much cooler temperatures, higher relative humidity, and potential for more widespread thunderstorm activity. While lightning efficiency may increase, increase coverage of thunderstorms and better organization with increasing shear should promote heavier cores and wetting rainfall potential. As such, no isolated thunderstorm areas were included at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0208 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z A rather expansive IsoDryT area was added as scattered to widespread mixed wet/dry thunderstorms are expected across central Oregon/vicinity tomorrow with more isolated coverage into western Oregon and western/central Washington. Late evening and nocturnal thunderstorms are possible in portions of central/eastern/northwest Oregon and western Washington. While wetting rain is likely in portions of central/eastern Oregon, the amount of lightning and dry to very dry fuels as evident by new ignitions and active to extreme fire behavior on large fires in the region support the introduction of an IsoDryT area. Storms will track generally northward at 10-20 knots likely producing abundant lightning, including outside of the cores, with drier air moving into portions of southern/central Oregon behind them. Precipitable water values will range from 0.7-1.3" in the IsoDryT area and training of storms with some of those higher PWAT values will lead to wetting rain in areas. The onshore flow/marine layer is also precluding including more of coastal Oregon in the IsoDryT area as it looks to deepen tomorrow, but thunderstorms may go up the Coast Ranges late tomorrow. Deep pyroconvection remains possible on very active large wildfires in the Northwest, north Idaho, and California. A complicating factor in this forecast is the quantity of smoke that will be in the region from existing fires and being transported southward from Canada. ..Nauslar.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1249 AM CDT Thu Sep 04 2025/ ...Synopsis... A secondary mid-level wave will traverse the Pacific Northwest on D2/Friday. This wave will bring much cooler temperatures, higher relative humidity, and potential for more widespread thunderstorm activity. While lightning efficiency may increase, increase coverage of thunderstorms and better organization with increasing shear should promote heavier cores and wetting rainfall potential. As such, no isolated thunderstorm areas were included at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0208 PM CDT Thu Sep 04 2025 Valid 051200Z - 061200Z A rather expansive IsoDryT area was added as scattered to widespread mixed wet/dry thunderstorms are expected across central Oregon/vicinity tomorrow with more isolated coverage into western Oregon and western/central Washington. Late evening and nocturnal thunderstorms are possible in portions of central/eastern/northwest Oregon and western Washington. While wetting rain is likely in portions of central/eastern Oregon, the amount of lightning and dry to very dry fuels as evident by new ignitions and active to extreme fire behavior on large fires in the region support the introduction of an IsoDryT area. Storms will track generally northward at 10-20 knots likely producing abundant lightning, including outside of the cores, with drier air moving into portions of southern/central Oregon behind them. Precipitable water values will range from 0.7-1.3" in the IsoDryT area and training of storms with some of those higher PWAT values will lead to wetting rain in areas. The onshore flow/marine layer is also precluding including more of coastal Oregon in the IsoDryT area as it looks to deepen tomorrow, but thunderstorms may go up the Coast Ranges late tomorrow. Deep pyroconvection remains possible on very active large wildfires in the Northwest, north Idaho, and California. A complicating factor in this forecast is the quantity of smoke that will be in the region from existing fires and being transported southward from Canada. ..Nauslar.. 09/04/2025 .PREV DISCUSSION... /ISSUED 1249 AM CDT Thu Sep 04 2025/ ...Synopsis... A secondary mid-level wave will traverse the Pacific Northwest on D2/Friday. This wave will bring much cooler temperatures, higher relative humidity, and potential for more widespread thunderstorm activity. While lightning efficiency may increase, increase coverage of thunderstorms and better organization with increasing shear should promote heavier cores and wetting rainfall potential. As such, no isolated thunderstorm areas were included at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 2031 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF SOUTHWESTERN THROUGH NORTH CENTRAL VIRGINIA...NORTHWESTERN NORTH CAROLINA
Mesoscale Discussion 2031 NWS Storm Prediction Center Norman OK 1241 PM CDT Thu Sep 04 2025 Areas affected...parts of southwestern through north central Virginia...northwestern North Carolina Concerning...Severe potential...Watch unlikely Valid 041741Z - 041945Z Probability of Watch Issuance...20 percent SUMMARY...Developing thunderstorm activity may increasingly pose a risk for sporadic damaging wind gusts through late afternoon. This seems unlikely to require a severe weather watch, but trends are being monitored. DISCUSSION...Destabilization is ongoing to the lee of the Blue Ridge, as insolation contributes to warming within a modestly moist boundary layer with surface dew points mostly in the lower/mid 60s F. It appears that this could contribute to CAPE in excess of 1000 J/kg, within a least a narrow corridor near the pre-frontal lee surface troughing. Forcing for ascent, associated with a short wave perturbation within the moderately strong larger-scale cyclonic southwesterly mid-level flow, is in the process of spreading across and east of the higher terrain to the west. This has provided continuing support for an organized area of thunderstorm development now spreading through southwestern Virginia, and into northwestern North Carolina, with new thunderstorms beginning to initiate within the pre-frontal troughing, northeastward toward the Greater Washington D.C vicinity. A gradual further intensification of the thunderstorm activity is probable in the presence of modest deep-layer shear through mid to late afternoon. Deep-layer southwesterly mean wind fields, however, through the lower/mid-troposphere, appear a generally modest 20-30 kts. This may be sufficient, coupled with modestly steep low-level lapse rates, to support potential for sporadic damaging wind gusts, but the lack of stronger instability suggests that the overall severe threat will remain limited. ..Kerr/Gleason.. 09/04/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...AKQ...LWX...RAH...RNK...GSP... LAT...LON 36218148 36858101 37288049 39097773 38417686 37657759 35838020 36218148 MOST PROBABLE PEAK WIND GUST...55-70 MPH Read more

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

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

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

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

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