Severe Storms

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0326 AM CST Tue Dec 05 2023 Valid 081200Z - 131200Z ...DISCUSSION... ...Ozarks/East TX to the Lower OH Valley/Deep South... The amplifying shortwave trough in the Great Basin vicinity at the start of D4 should become highly amplified over the central states and roughly centered across much of the MS Valley near 12Z/Sun. This scenario is widely supported by the 00Z ECMWF/GEFS ensemble means and deterministic ECMWF/UKMET/CMC runs. Poleward moisture transport from the western Gulf will displace an initially modified CP air mass with low-level warm theta-e advection becoming pronounced on D4/Fri night. This should result in mainly elevated thunderstorms within the strengthening warm conveyor near the developing surface cyclone in the Ozarks vicinity. A low-probability severe threat is apparent in this region south-southwest towards the Ark-La-Tex. Greater severe-weather potential should develop on D5/Sat during the day as mid to upper-level southwesterlies strengthen across the warm sector and instability is boosted by diurnal surface heating, centered on east TX towards the Ark-La-Miss. Convection will likely become widespread by afternoon. The potential for extensive overturning lowers confidence in the degree of north/east extent of the severe threat away from the highlighted 15 percent area. As such, a broad low-probability severe threat should be implied to the north/east from the Lower OH Valley to the Deep South. ...Southeast to Mid-Atlantic States... Potential exists for robust cyclogenesis to peak in the late D5 to D6 time frame on Sun across parts of the Midwest to Great Lakes. The 00Z deterministic ECMWF is particularly intense as the highly amplified upper trough across the MS Valley becomes negatively tilted over the East on D6/Sun. However, ensemble spread within the ECMWF/GEFS appears quite large regarding synoptic details, and this is coupled with a high likelihood of a thermodynamically limited warm sector given weak mid-level lapse rates and negligible to meager buoyancy. But with at least conditional potential for extreme low-level wind fields to potentially overlap upper 50s to mid 60s surface dew points, low severe probabilities appear warranted. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0326 AM CST Tue Dec 05 2023 Valid 081200Z - 131200Z ...DISCUSSION... ...Ozarks/East TX to the Lower OH Valley/Deep South... The amplifying shortwave trough in the Great Basin vicinity at the start of D4 should become highly amplified over the central states and roughly centered across much of the MS Valley near 12Z/Sun. This scenario is widely supported by the 00Z ECMWF/GEFS ensemble means and deterministic ECMWF/UKMET/CMC runs. Poleward moisture transport from the western Gulf will displace an initially modified CP air mass with low-level warm theta-e advection becoming pronounced on D4/Fri night. This should result in mainly elevated thunderstorms within the strengthening warm conveyor near the developing surface cyclone in the Ozarks vicinity. A low-probability severe threat is apparent in this region south-southwest towards the Ark-La-Tex. Greater severe-weather potential should develop on D5/Sat during the day as mid to upper-level southwesterlies strengthen across the warm sector and instability is boosted by diurnal surface heating, centered on east TX towards the Ark-La-Miss. Convection will likely become widespread by afternoon. The potential for extensive overturning lowers confidence in the degree of north/east extent of the severe threat away from the highlighted 15 percent area. As such, a broad low-probability severe threat should be implied to the north/east from the Lower OH Valley to the Deep South. ...Southeast to Mid-Atlantic States... Potential exists for robust cyclogenesis to peak in the late D5 to D6 time frame on Sun across parts of the Midwest to Great Lakes. The 00Z deterministic ECMWF is particularly intense as the highly amplified upper trough across the MS Valley becomes negatively tilted over the East on D6/Sun. However, ensemble spread within the ECMWF/GEFS appears quite large regarding synoptic details, and this is coupled with a high likelihood of a thermodynamically limited warm sector given weak mid-level lapse rates and negligible to meager buoyancy. But with at least conditional potential for extreme low-level wind fields to potentially overlap upper 50s to mid 60s surface dew points, low severe probabilities appear warranted. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0326 AM CST Tue Dec 05 2023 Valid 081200Z - 131200Z ...DISCUSSION... ...Ozarks/East TX to the Lower OH Valley/Deep South... The amplifying shortwave trough in the Great Basin vicinity at the start of D4 should become highly amplified over the central states and roughly centered across much of the MS Valley near 12Z/Sun. This scenario is widely supported by the 00Z ECMWF/GEFS ensemble means and deterministic ECMWF/UKMET/CMC runs. Poleward moisture transport from the western Gulf will displace an initially modified CP air mass with low-level warm theta-e advection becoming pronounced on D4/Fri night. This should result in mainly elevated thunderstorms within the strengthening warm conveyor near the developing surface cyclone in the Ozarks vicinity. A low-probability severe threat is apparent in this region south-southwest towards the Ark-La-Tex. Greater severe-weather potential should develop on D5/Sat during the day as mid to upper-level southwesterlies strengthen across the warm sector and instability is boosted by diurnal surface heating, centered on east TX towards the Ark-La-Miss. Convection will likely become widespread by afternoon. The potential for extensive overturning lowers confidence in the degree of north/east extent of the severe threat away from the highlighted 15 percent area. As such, a broad low-probability severe threat should be implied to the north/east from the Lower OH Valley to the Deep South. ...Southeast to Mid-Atlantic States... Potential exists for robust cyclogenesis to peak in the late D5 to D6 time frame on Sun across parts of the Midwest to Great Lakes. The 00Z deterministic ECMWF is particularly intense as the highly amplified upper trough across the MS Valley becomes negatively tilted over the East on D6/Sun. However, ensemble spread within the ECMWF/GEFS appears quite large regarding synoptic details, and this is coupled with a high likelihood of a thermodynamically limited warm sector given weak mid-level lapse rates and negligible to meager buoyancy. But with at least conditional potential for extreme low-level wind fields to potentially overlap upper 50s to mid 60s surface dew points, low severe probabilities appear warranted. Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0121 AM CST Tue Dec 05 2023 Valid 071200Z - 081200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Thursday. ...Discussion... Thunderstorm potential will be negligible across much of the CONUS on Thursday. The lone exception will be over the Pacific Northwest, where sporadic lightning flashes are possible, mainly during the first half of the period near the coast. The next in a series of shortwave troughs will impinge on the Pacific Northwest coast on Thursday, before digging towards the northern Great Basin by Thursday night. Already steep 700-500 mb lapse rates in the wake of a trough passage on D2/Wednesday, will steepen further between 8 to 8.5 C/km as cold 500-mb temperatures from -30 to -35 C become common. This should compensate for gradually decreasing boundary-layer moisture with low 40s surface dew points holding along the coast through Thursday afternoon. Scant surface-based buoyancy is anticipated with multiple rounds of scattered low-topped convection. Similar to D2, sporadic lightning flashes will be possible, although focused somewhat farther north along the OR/WA coast and mainly in the morning to afternoon. ..Grams.. 12/05/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0121 AM CST Tue Dec 05 2023 Valid 071200Z - 081200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Thursday. ...Discussion... Thunderstorm potential will be negligible across much of the CONUS on Thursday. The lone exception will be over the Pacific Northwest, where sporadic lightning flashes are possible, mainly during the first half of the period near the coast. The next in a series of shortwave troughs will impinge on the Pacific Northwest coast on Thursday, before digging towards the northern Great Basin by Thursday night. Already steep 700-500 mb lapse rates in the wake of a trough passage on D2/Wednesday, will steepen further between 8 to 8.5 C/km as cold 500-mb temperatures from -30 to -35 C become common. This should compensate for gradually decreasing boundary-layer moisture with low 40s surface dew points holding along the coast through Thursday afternoon. Scant surface-based buoyancy is anticipated with multiple rounds of scattered low-topped convection. Similar to D2, sporadic lightning flashes will be possible, although focused somewhat farther north along the OR/WA coast and mainly in the morning to afternoon. ..Grams.. 12/05/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0121 AM CST Tue Dec 05 2023 Valid 071200Z - 081200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Thursday. ...Discussion... Thunderstorm potential will be negligible across much of the CONUS on Thursday. The lone exception will be over the Pacific Northwest, where sporadic lightning flashes are possible, mainly during the first half of the period near the coast. The next in a series of shortwave troughs will impinge on the Pacific Northwest coast on Thursday, before digging towards the northern Great Basin by Thursday night. Already steep 700-500 mb lapse rates in the wake of a trough passage on D2/Wednesday, will steepen further between 8 to 8.5 C/km as cold 500-mb temperatures from -30 to -35 C become common. This should compensate for gradually decreasing boundary-layer moisture with low 40s surface dew points holding along the coast through Thursday afternoon. Scant surface-based buoyancy is anticipated with multiple rounds of scattered low-topped convection. Similar to D2, sporadic lightning flashes will be possible, although focused somewhat farther north along the OR/WA coast and mainly in the morning to afternoon. ..Grams.. 12/05/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0121 AM CST Tue Dec 05 2023 Valid 071200Z - 081200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Thursday. ...Discussion... Thunderstorm potential will be negligible across much of the CONUS on Thursday. The lone exception will be over the Pacific Northwest, where sporadic lightning flashes are possible, mainly during the first half of the period near the coast. The next in a series of shortwave troughs will impinge on the Pacific Northwest coast on Thursday, before digging towards the northern Great Basin by Thursday night. Already steep 700-500 mb lapse rates in the wake of a trough passage on D2/Wednesday, will steepen further between 8 to 8.5 C/km as cold 500-mb temperatures from -30 to -35 C become common. This should compensate for gradually decreasing boundary-layer moisture with low 40s surface dew points holding along the coast through Thursday afternoon. Scant surface-based buoyancy is anticipated with multiple rounds of scattered low-topped convection. Similar to D2, sporadic lightning flashes will be possible, although focused somewhat farther north along the OR/WA coast and mainly in the morning to afternoon. ..Grams.. 12/05/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1142 PM CST Mon Dec 04 2023 Valid 061200Z - 071200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Wednesday. ...Discussion... Thunderstorm potential will remain negligible across much of the CONUS. Sporadic lightning flashes are possible over a portion of northern CA to coastal OR, mainly during the late afternoon and evening on Wednesday. A shortwave trough over the northeast Pacific will move inland across northern CA and the Northwest. In the wake of trough passage, cooler mid-level temperatures amid an expanding plume of steep lapse rates will overspread much of the Pacific Northwest. As this occurs, scant surface-based buoyancy should develop along coastal OR into a portion of northern CA towards late afternoon. 00Z HREF guidance suggests scattered low-topped convection will become common in this time frame, with the deepest convection capable of producing sporadic lightning flashes. ..Grams.. 12/05/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1142 PM CST Mon Dec 04 2023 Valid 061200Z - 071200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Wednesday. ...Discussion... Thunderstorm potential will remain negligible across much of the CONUS. Sporadic lightning flashes are possible over a portion of northern CA to coastal OR, mainly during the late afternoon and evening on Wednesday. A shortwave trough over the northeast Pacific will move inland across northern CA and the Northwest. In the wake of trough passage, cooler mid-level temperatures amid an expanding plume of steep lapse rates will overspread much of the Pacific Northwest. As this occurs, scant surface-based buoyancy should develop along coastal OR into a portion of northern CA towards late afternoon. 00Z HREF guidance suggests scattered low-topped convection will become common in this time frame, with the deepest convection capable of producing sporadic lightning flashes. ..Grams.. 12/05/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1142 PM CST Mon Dec 04 2023 Valid 061200Z - 071200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Wednesday. ...Discussion... Thunderstorm potential will remain negligible across much of the CONUS. Sporadic lightning flashes are possible over a portion of northern CA to coastal OR, mainly during the late afternoon and evening on Wednesday. A shortwave trough over the northeast Pacific will move inland across northern CA and the Northwest. In the wake of trough passage, cooler mid-level temperatures amid an expanding plume of steep lapse rates will overspread much of the Pacific Northwest. As this occurs, scant surface-based buoyancy should develop along coastal OR into a portion of northern CA towards late afternoon. 00Z HREF guidance suggests scattered low-topped convection will become common in this time frame, with the deepest convection capable of producing sporadic lightning flashes. ..Grams.. 12/05/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1142 PM CST Mon Dec 04 2023 Valid 061200Z - 071200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Wednesday. ...Discussion... Thunderstorm potential will remain negligible across much of the CONUS. Sporadic lightning flashes are possible over a portion of northern CA to coastal OR, mainly during the late afternoon and evening on Wednesday. A shortwave trough over the northeast Pacific will move inland across northern CA and the Northwest. In the wake of trough passage, cooler mid-level temperatures amid an expanding plume of steep lapse rates will overspread much of the Pacific Northwest. As this occurs, scant surface-based buoyancy should develop along coastal OR into a portion of northern CA towards late afternoon. 00Z HREF guidance suggests scattered low-topped convection will become common in this time frame, with the deepest convection capable of producing sporadic lightning flashes. ..Grams.. 12/05/2023 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1122 PM CST Mon Dec 04 2023 Valid 061200Z - 071200Z ...NO CRITICAL AREAS... ...Synopsis... The upper-level ridge will continue to shift eastward into the Missouri/Mississippi Valley regions on Wednesday. A trough will begin to develop into the West once again, but will be relatively ill-defined initially. At the surface, a combination of a modestly intensifying surface high in the Southeast and broad surface low pressure in the northern Rockies southward into the High Plains will increase the pressure gradient within parts of the Plains. Gusty south/southwest winds are possible from the southern High Plains into the central Plains and parts of the Upper Midwest. Temperatures should remain rather cool farther north and keep RH elevated. Warmer temperatures are expected farther south and within areas of stronger downslope winds. Pockets of locally elevated fire weather are possible in the southern High Plains and perhaps parts of southeast Wyoming should sufficiently dry fine fuels exist. ..Wendt.. 12/05/2023 ...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 1122 PM CST Mon Dec 04 2023 Valid 061200Z - 071200Z ...NO CRITICAL AREAS... ...Synopsis... The upper-level ridge will continue to shift eastward into the Missouri/Mississippi Valley regions on Wednesday. A trough will begin to develop into the West once again, but will be relatively ill-defined initially. At the surface, a combination of a modestly intensifying surface high in the Southeast and broad surface low pressure in the northern Rockies southward into the High Plains will increase the pressure gradient within parts of the Plains. Gusty south/southwest winds are possible from the southern High Plains into the central Plains and parts of the Upper Midwest. Temperatures should remain rather cool farther north and keep RH elevated. Warmer temperatures are expected farther south and within areas of stronger downslope winds. Pockets of locally elevated fire weather are possible in the southern High Plains and perhaps parts of southeast Wyoming should sufficiently dry fine fuels exist. ..Wendt.. 12/05/2023 ...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 1122 PM CST Mon Dec 04 2023 Valid 061200Z - 071200Z ...NO CRITICAL AREAS... ...Synopsis... The upper-level ridge will continue to shift eastward into the Missouri/Mississippi Valley regions on Wednesday. A trough will begin to develop into the West once again, but will be relatively ill-defined initially. At the surface, a combination of a modestly intensifying surface high in the Southeast and broad surface low pressure in the northern Rockies southward into the High Plains will increase the pressure gradient within parts of the Plains. Gusty south/southwest winds are possible from the southern High Plains into the central Plains and parts of the Upper Midwest. Temperatures should remain rather cool farther north and keep RH elevated. Warmer temperatures are expected farther south and within areas of stronger downslope winds. Pockets of locally elevated fire weather are possible in the southern High Plains and perhaps parts of southeast Wyoming should sufficiently dry fine fuels exist. ..Wendt.. 12/05/2023 ...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 1122 PM CST Mon Dec 04 2023 Valid 061200Z - 071200Z ...NO CRITICAL AREAS... ...Synopsis... The upper-level ridge will continue to shift eastward into the Missouri/Mississippi Valley regions on Wednesday. A trough will begin to develop into the West once again, but will be relatively ill-defined initially. At the surface, a combination of a modestly intensifying surface high in the Southeast and broad surface low pressure in the northern Rockies southward into the High Plains will increase the pressure gradient within parts of the Plains. Gusty south/southwest winds are possible from the southern High Plains into the central Plains and parts of the Upper Midwest. Temperatures should remain rather cool farther north and keep RH elevated. Warmer temperatures are expected farther south and within areas of stronger downslope winds. Pockets of locally elevated fire weather are possible in the southern High Plains and perhaps parts of southeast Wyoming should sufficiently dry fine fuels exist. ..Wendt.. 12/05/2023 ...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 1120 PM CST Mon Dec 04 2023 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... ...Synopsis... An upper-level ridge will shift eastward over the Divide today. At the surface, high pressure will strengthen in the Plains as it moves southeastward with time. Surface high pressure will also remain within the Great Basin into the Western Slope. Fire weather concerns throughout the CONUS should remain low given generally unreceptive fuels and light winds. Some stronger offshore winds are likely in southern California. These winds will peak this morning before weakening through the day. Though fuels are not overly receptive and the lowest RH will not phase well with the strongest winds, locally elevated conditions would be possible where pockets of dry fuels exits within the terrain. ..Wendt.. 12/05/2023 ...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 1120 PM CST Mon Dec 04 2023 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... ...Synopsis... An upper-level ridge will shift eastward over the Divide today. At the surface, high pressure will strengthen in the Plains as it moves southeastward with time. Surface high pressure will also remain within the Great Basin into the Western Slope. Fire weather concerns throughout the CONUS should remain low given generally unreceptive fuels and light winds. Some stronger offshore winds are likely in southern California. These winds will peak this morning before weakening through the day. Though fuels are not overly receptive and the lowest RH will not phase well with the strongest winds, locally elevated conditions would be possible where pockets of dry fuels exits within the terrain. ..Wendt.. 12/05/2023 ...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 1120 PM CST Mon Dec 04 2023 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... ...Synopsis... An upper-level ridge will shift eastward over the Divide today. At the surface, high pressure will strengthen in the Plains as it moves southeastward with time. Surface high pressure will also remain within the Great Basin into the Western Slope. Fire weather concerns throughout the CONUS should remain low given generally unreceptive fuels and light winds. Some stronger offshore winds are likely in southern California. These winds will peak this morning before weakening through the day. Though fuels are not overly receptive and the lowest RH will not phase well with the strongest winds, locally elevated conditions would be possible where pockets of dry fuels exits within the terrain. ..Wendt.. 12/05/2023 ...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 1120 PM CST Mon Dec 04 2023 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... ...Synopsis... An upper-level ridge will shift eastward over the Divide today. At the surface, high pressure will strengthen in the Plains as it moves southeastward with time. Surface high pressure will also remain within the Great Basin into the Western Slope. Fire weather concerns throughout the CONUS should remain low given generally unreceptive fuels and light winds. Some stronger offshore winds are likely in southern California. These winds will peak this morning before weakening through the day. Though fuels are not overly receptive and the lowest RH will not phase well with the strongest winds, locally elevated conditions would be possible where pockets of dry fuels exits within the terrain. ..Wendt.. 12/05/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1116 PM CST Mon Dec 04 2023 Valid 051200Z - 061200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are not expected across the contiguous United States. ...Discussion... Large-scale pattern will prove unfavorable for thunderstorms today across the CONUS. Offshore flow will prevail across most of the Atlantic/Gulf Coasts and any appreciable buoyancy has been shunted well south and east of the United States. Across the western US, warm conveyor will gradually sag south along the west Coast, but the primary upper trough will hold well offshore. Weak instability may be noted within the conveyor, but primarily west of -125 longitude. Even within this corridor, elevated convection should remain too shallow/weak to warrant any meaningful risk for lightning. ..Darrow.. 12/05/2023 Read more