Severe Storms

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0211 AM CDT Mon Sep 16 2024 Valid 181200Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms are not expected on Wednesday. ...Great Plains... In the wake of extensive convective overturning on D2 across the High Plains, remnant outflows should be present over the lower plains as convection decays Wednesday morning. The northern High Plains shortwave trough and parent mid-level circulation should become vertically stacked with the attendant surface cyclone over eastern MT. This will slow its advance considerably on Wednesday, as it eventually drifts towards far southeast SK. Where a confined plume of moderate buoyancy may develop on Wednesday afternoon from the Mid-MO Valley to the TX Panhandle, 500-mb temperatures will be relatively warm, from -4 to -8 C southwest to northeast. This will foster weak 700-500 mb lapse rates. Beyond weakly convergent convective outflows, large-scale ascent appears nebulous, and convective signals across most models seem limited and mesoscale-focused. While low-end supercell wind profiles could develop during the late afternoon to early evening, the aforementioned limiting factors suggest severe hail/wind potential may be subdued and very localized. As such, will defer to later outlooks for any level 1-MRGL risk highlights. ..Grams.. 09/16/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0211 AM CDT Mon Sep 16 2024 Valid 181200Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms are not expected on Wednesday. ...Great Plains... In the wake of extensive convective overturning on D2 across the High Plains, remnant outflows should be present over the lower plains as convection decays Wednesday morning. The northern High Plains shortwave trough and parent mid-level circulation should become vertically stacked with the attendant surface cyclone over eastern MT. This will slow its advance considerably on Wednesday, as it eventually drifts towards far southeast SK. Where a confined plume of moderate buoyancy may develop on Wednesday afternoon from the Mid-MO Valley to the TX Panhandle, 500-mb temperatures will be relatively warm, from -4 to -8 C southwest to northeast. This will foster weak 700-500 mb lapse rates. Beyond weakly convergent convective outflows, large-scale ascent appears nebulous, and convective signals across most models seem limited and mesoscale-focused. While low-end supercell wind profiles could develop during the late afternoon to early evening, the aforementioned limiting factors suggest severe hail/wind potential may be subdued and very localized. As such, will defer to later outlooks for any level 1-MRGL risk highlights. ..Grams.. 09/16/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0211 AM CDT Mon Sep 16 2024 Valid 181200Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms are not expected on Wednesday. ...Great Plains... In the wake of extensive convective overturning on D2 across the High Plains, remnant outflows should be present over the lower plains as convection decays Wednesday morning. The northern High Plains shortwave trough and parent mid-level circulation should become vertically stacked with the attendant surface cyclone over eastern MT. This will slow its advance considerably on Wednesday, as it eventually drifts towards far southeast SK. Where a confined plume of moderate buoyancy may develop on Wednesday afternoon from the Mid-MO Valley to the TX Panhandle, 500-mb temperatures will be relatively warm, from -4 to -8 C southwest to northeast. This will foster weak 700-500 mb lapse rates. Beyond weakly convergent convective outflows, large-scale ascent appears nebulous, and convective signals across most models seem limited and mesoscale-focused. While low-end supercell wind profiles could develop during the late afternoon to early evening, the aforementioned limiting factors suggest severe hail/wind potential may be subdued and very localized. As such, will defer to later outlooks for any level 1-MRGL risk highlights. ..Grams.. 09/16/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0156 AM CDT Mon Sep 16 2024 Valid 171200Z - 181200Z ...Synopsis... Strong deep-layer south-southwesterly flow preceding an amplified large-scale trough over the West will impinge on the central High Plains during the day. Here, a tightening pressure gradient along a pronounced lee trough, and boundary-layer mixing into the strong flow aloft, will favor 20-25 mph sustained southerly surface winds (with higher gusts). These winds should overlap 20-25 percent RH for a few hours, before a cold front and related precipitation overspread the area from the west during the evening. Given receptive fuels across the area, elevated fire-weather conditions are expected during the afternoon (prior to the arrival of precipitation). ..Weinman.. 09/16/2024 ...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 0156 AM CDT Mon Sep 16 2024 Valid 171200Z - 181200Z ...Synopsis... Strong deep-layer south-southwesterly flow preceding an amplified large-scale trough over the West will impinge on the central High Plains during the day. Here, a tightening pressure gradient along a pronounced lee trough, and boundary-layer mixing into the strong flow aloft, will favor 20-25 mph sustained southerly surface winds (with higher gusts). These winds should overlap 20-25 percent RH for a few hours, before a cold front and related precipitation overspread the area from the west during the evening. Given receptive fuels across the area, elevated fire-weather conditions are expected during the afternoon (prior to the arrival of precipitation). ..Weinman.. 09/16/2024 ...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 0156 AM CDT Mon Sep 16 2024 Valid 171200Z - 181200Z ...Synopsis... Strong deep-layer south-southwesterly flow preceding an amplified large-scale trough over the West will impinge on the central High Plains during the day. Here, a tightening pressure gradient along a pronounced lee trough, and boundary-layer mixing into the strong flow aloft, will favor 20-25 mph sustained southerly surface winds (with higher gusts). These winds should overlap 20-25 percent RH for a few hours, before a cold front and related precipitation overspread the area from the west during the evening. Given receptive fuels across the area, elevated fire-weather conditions are expected during the afternoon (prior to the arrival of precipitation). ..Weinman.. 09/16/2024 ...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 0156 AM CDT Mon Sep 16 2024 Valid 171200Z - 181200Z ...Synopsis... Strong deep-layer south-southwesterly flow preceding an amplified large-scale trough over the West will impinge on the central High Plains during the day. Here, a tightening pressure gradient along a pronounced lee trough, and boundary-layer mixing into the strong flow aloft, will favor 20-25 mph sustained southerly surface winds (with higher gusts). These winds should overlap 20-25 percent RH for a few hours, before a cold front and related precipitation overspread the area from the west during the evening. Given receptive fuels across the area, elevated fire-weather conditions are expected during the afternoon (prior to the arrival of precipitation). ..Weinman.. 09/16/2024 ...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 0156 AM CDT Mon Sep 16 2024 Valid 171200Z - 181200Z ...Synopsis... Strong deep-layer south-southwesterly flow preceding an amplified large-scale trough over the West will impinge on the central High Plains during the day. Here, a tightening pressure gradient along a pronounced lee trough, and boundary-layer mixing into the strong flow aloft, will favor 20-25 mph sustained southerly surface winds (with higher gusts). These winds should overlap 20-25 percent RH for a few hours, before a cold front and related precipitation overspread the area from the west during the evening. Given receptive fuels across the area, elevated fire-weather conditions are expected during the afternoon (prior to the arrival of precipitation). ..Weinman.. 09/16/2024 ...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 0156 AM CDT Mon Sep 16 2024 Valid 171200Z - 181200Z ...Synopsis... Strong deep-layer south-southwesterly flow preceding an amplified large-scale trough over the West will impinge on the central High Plains during the day. Here, a tightening pressure gradient along a pronounced lee trough, and boundary-layer mixing into the strong flow aloft, will favor 20-25 mph sustained southerly surface winds (with higher gusts). These winds should overlap 20-25 percent RH for a few hours, before a cold front and related precipitation overspread the area from the west during the evening. Given receptive fuels across the area, elevated fire-weather conditions are expected during the afternoon (prior to the arrival of precipitation). ..Weinman.. 09/16/2024 ...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 0156 AM CDT Mon Sep 16 2024 Valid 171200Z - 181200Z ...Synopsis... Strong deep-layer south-southwesterly flow preceding an amplified large-scale trough over the West will impinge on the central High Plains during the day. Here, a tightening pressure gradient along a pronounced lee trough, and boundary-layer mixing into the strong flow aloft, will favor 20-25 mph sustained southerly surface winds (with higher gusts). These winds should overlap 20-25 percent RH for a few hours, before a cold front and related precipitation overspread the area from the west during the evening. Given receptive fuels across the area, elevated fire-weather conditions are expected during the afternoon (prior to the arrival of precipitation). ..Weinman.. 09/16/2024 ...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 0156 AM CDT Mon Sep 16 2024 Valid 161200Z - 171200Z ...Synopsis... Within the base of a deep midlevel cyclone moving eastward across the Great Basin, a related jet streak will overspread the Lower CO River Valley. Here, boundary-layer mixing into the strengthening flow aloft, coupled with a tightening pressure gradient peripheral to an evolving surface cyclone, will favor 20-25 mph sustained southerly surface winds. Despite a gradual increase in moisture/RH, diurnal heating should still support a corridor of around 20 percent RH amid the strong surface winds along the Lower CO River Valley -- favoring elevated fire-weather conditions. Elevated fire-weather conditions are also expected over portions of the central High Plains -- where breezy/gusty southerly surface winds will overlap 20 percent RH near a lee trough during the afternoon. While spotty rainfall during the past 24 hours could limit fuel receptiveness over parts of the area, mostly receptive fuels should still yield some fire-weather risk. Farther east, warm/dry conditions are expected over portions of OH and KY -- along the southwestern periphery of an expansive surface anticyclone. While sustained surface winds around 10 mph should limit the overall fire-weather threat, around 20 percent RH and very dry/receptive fuels will still pose localized fire-weather concerns during the afternoon. ..Weinman.. 09/16/2024 ...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 0156 AM CDT Mon Sep 16 2024 Valid 161200Z - 171200Z ...Synopsis... Within the base of a deep midlevel cyclone moving eastward across the Great Basin, a related jet streak will overspread the Lower CO River Valley. Here, boundary-layer mixing into the strengthening flow aloft, coupled with a tightening pressure gradient peripheral to an evolving surface cyclone, will favor 20-25 mph sustained southerly surface winds. Despite a gradual increase in moisture/RH, diurnal heating should still support a corridor of around 20 percent RH amid the strong surface winds along the Lower CO River Valley -- favoring elevated fire-weather conditions. Elevated fire-weather conditions are also expected over portions of the central High Plains -- where breezy/gusty southerly surface winds will overlap 20 percent RH near a lee trough during the afternoon. While spotty rainfall during the past 24 hours could limit fuel receptiveness over parts of the area, mostly receptive fuels should still yield some fire-weather risk. Farther east, warm/dry conditions are expected over portions of OH and KY -- along the southwestern periphery of an expansive surface anticyclone. While sustained surface winds around 10 mph should limit the overall fire-weather threat, around 20 percent RH and very dry/receptive fuels will still pose localized fire-weather concerns during the afternoon. ..Weinman.. 09/16/2024 ...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 0156 AM CDT Mon Sep 16 2024 Valid 161200Z - 171200Z ...Synopsis... Within the base of a deep midlevel cyclone moving eastward across the Great Basin, a related jet streak will overspread the Lower CO River Valley. Here, boundary-layer mixing into the strengthening flow aloft, coupled with a tightening pressure gradient peripheral to an evolving surface cyclone, will favor 20-25 mph sustained southerly surface winds. Despite a gradual increase in moisture/RH, diurnal heating should still support a corridor of around 20 percent RH amid the strong surface winds along the Lower CO River Valley -- favoring elevated fire-weather conditions. Elevated fire-weather conditions are also expected over portions of the central High Plains -- where breezy/gusty southerly surface winds will overlap 20 percent RH near a lee trough during the afternoon. While spotty rainfall during the past 24 hours could limit fuel receptiveness over parts of the area, mostly receptive fuels should still yield some fire-weather risk. Farther east, warm/dry conditions are expected over portions of OH and KY -- along the southwestern periphery of an expansive surface anticyclone. While sustained surface winds around 10 mph should limit the overall fire-weather threat, around 20 percent RH and very dry/receptive fuels will still pose localized fire-weather concerns during the afternoon. ..Weinman.. 09/16/2024 ...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 0156 AM CDT Mon Sep 16 2024 Valid 161200Z - 171200Z ...Synopsis... Within the base of a deep midlevel cyclone moving eastward across the Great Basin, a related jet streak will overspread the Lower CO River Valley. Here, boundary-layer mixing into the strengthening flow aloft, coupled with a tightening pressure gradient peripheral to an evolving surface cyclone, will favor 20-25 mph sustained southerly surface winds. Despite a gradual increase in moisture/RH, diurnal heating should still support a corridor of around 20 percent RH amid the strong surface winds along the Lower CO River Valley -- favoring elevated fire-weather conditions. Elevated fire-weather conditions are also expected over portions of the central High Plains -- where breezy/gusty southerly surface winds will overlap 20 percent RH near a lee trough during the afternoon. While spotty rainfall during the past 24 hours could limit fuel receptiveness over parts of the area, mostly receptive fuels should still yield some fire-weather risk. Farther east, warm/dry conditions are expected over portions of OH and KY -- along the southwestern periphery of an expansive surface anticyclone. While sustained surface winds around 10 mph should limit the overall fire-weather threat, around 20 percent RH and very dry/receptive fuels will still pose localized fire-weather concerns during the afternoon. ..Weinman.. 09/16/2024 ...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 0156 AM CDT Mon Sep 16 2024 Valid 161200Z - 171200Z ...Synopsis... Within the base of a deep midlevel cyclone moving eastward across the Great Basin, a related jet streak will overspread the Lower CO River Valley. Here, boundary-layer mixing into the strengthening flow aloft, coupled with a tightening pressure gradient peripheral to an evolving surface cyclone, will favor 20-25 mph sustained southerly surface winds. Despite a gradual increase in moisture/RH, diurnal heating should still support a corridor of around 20 percent RH amid the strong surface winds along the Lower CO River Valley -- favoring elevated fire-weather conditions. Elevated fire-weather conditions are also expected over portions of the central High Plains -- where breezy/gusty southerly surface winds will overlap 20 percent RH near a lee trough during the afternoon. While spotty rainfall during the past 24 hours could limit fuel receptiveness over parts of the area, mostly receptive fuels should still yield some fire-weather risk. Farther east, warm/dry conditions are expected over portions of OH and KY -- along the southwestern periphery of an expansive surface anticyclone. While sustained surface winds around 10 mph should limit the overall fire-weather threat, around 20 percent RH and very dry/receptive fuels will still pose localized fire-weather concerns during the afternoon. ..Weinman.. 09/16/2024 ...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 0156 AM CDT Mon Sep 16 2024 Valid 161200Z - 171200Z ...Synopsis... Within the base of a deep midlevel cyclone moving eastward across the Great Basin, a related jet streak will overspread the Lower CO River Valley. Here, boundary-layer mixing into the strengthening flow aloft, coupled with a tightening pressure gradient peripheral to an evolving surface cyclone, will favor 20-25 mph sustained southerly surface winds. Despite a gradual increase in moisture/RH, diurnal heating should still support a corridor of around 20 percent RH amid the strong surface winds along the Lower CO River Valley -- favoring elevated fire-weather conditions. Elevated fire-weather conditions are also expected over portions of the central High Plains -- where breezy/gusty southerly surface winds will overlap 20 percent RH near a lee trough during the afternoon. While spotty rainfall during the past 24 hours could limit fuel receptiveness over parts of the area, mostly receptive fuels should still yield some fire-weather risk. Farther east, warm/dry conditions are expected over portions of OH and KY -- along the southwestern periphery of an expansive surface anticyclone. While sustained surface winds around 10 mph should limit the overall fire-weather threat, around 20 percent RH and very dry/receptive fuels will still pose localized fire-weather concerns during the afternoon. ..Weinman.. 09/16/2024 ...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 0156 AM CDT Mon Sep 16 2024 Valid 161200Z - 171200Z ...Synopsis... Within the base of a deep midlevel cyclone moving eastward across the Great Basin, a related jet streak will overspread the Lower CO River Valley. Here, boundary-layer mixing into the strengthening flow aloft, coupled with a tightening pressure gradient peripheral to an evolving surface cyclone, will favor 20-25 mph sustained southerly surface winds. Despite a gradual increase in moisture/RH, diurnal heating should still support a corridor of around 20 percent RH amid the strong surface winds along the Lower CO River Valley -- favoring elevated fire-weather conditions. Elevated fire-weather conditions are also expected over portions of the central High Plains -- where breezy/gusty southerly surface winds will overlap 20 percent RH near a lee trough during the afternoon. While spotty rainfall during the past 24 hours could limit fuel receptiveness over parts of the area, mostly receptive fuels should still yield some fire-weather risk. Farther east, warm/dry conditions are expected over portions of OH and KY -- along the southwestern periphery of an expansive surface anticyclone. While sustained surface winds around 10 mph should limit the overall fire-weather threat, around 20 percent RH and very dry/receptive fuels will still pose localized fire-weather concerns during the afternoon. ..Weinman.. 09/16/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Mon Sep 16 2024 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE CENTRAL HIGH PLAINS AND EASTERN MT... ...SUMMARY... Isolated to scattered severe gusts and hail are possible Tuesday across a large swath of the High Plains region, mainly from late afternoon into the evening. The greater concentrations of severe storms may occur over the central High Plains and eastern Montana. ...High Plains... A mid/upper-level shortwave trough initially over the eastern Great Basin will take on a negative tilt as it advances towards the northern High Plains. Deep lee cyclogenesis is expected over far northeast WY/southeast MT, with a warm front arcing east across parts of the Dakotas. This low will advance north then northwestward across eastern MT through 12Z Wednesday. Large-scale ascent will be pronounced within this synoptic regime, with favorable upper-level difluence, mid-level height falls, and low-level convergence. However, weak buoyancy and modest mid-level lapse rates will characterize much of the environment to the south of the surface cyclone and warm front. Aided by a subtropical moisture plume over the Southwest, morning convection near the Four Corners region should move across the higher terrain and expand in coverage into the afternoon. High-based storms over the central and southern High Plains will progress into a well-mixed boundary layer that may initially be devoid of appreciable CAPE. This lack of greater buoyancy during the late afternoon to early evening (outside of areas north of the warm front) yields some uncertainty regarding the degree of storm intensity into the lower elevations. But with scattered to eventually widespread convection expected with time, extensive outflows are expected to push east. The most likely corridor for severe gusts appears to be over the central High Plains where the most pronounced 700-500 mb flow should advance ahead of the negative-tilt shortwave trough. Farther south, a few supercells may initially develop from parts of NM into southeast CO. Modest mid-level lapse rates should temper updraft vigor, but marginally severe hail along with isolated severe gusts will be possible. More favorable low-level moisture with steep mid-level lapse rates will reside near/north of the warm front, supporting moderate buoyancy from northeast MT into ND. While stronger ascent and deep-layer flow may not impinge upon areas north of the front until near sunset, organized storms should develop over the higher terrain by late afternoon and spread north within a backed mid-level flow regime. A few supercells along with an organized cluster or two may impinge on the greater downstream buoyancy plume, maintaining threats for large hail and severe gusts into Tuesday night. ...Eastern NC and southeast VA... While confidence is modest with the probable inland evolution of PTC 8, the bulk signal across guidance is for a weakening low-level wind field by Tuesday morning across the NC/VA coastal plain. The potential for low-topped supercells capable of brief tornadoes appears too low beyond 12Z Tuesday to warrant a risk highlight. ..Grams.. 09/16/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Mon Sep 16 2024 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE CENTRAL HIGH PLAINS AND EASTERN MT... ...SUMMARY... Isolated to scattered severe gusts and hail are possible Tuesday across a large swath of the High Plains region, mainly from late afternoon into the evening. The greater concentrations of severe storms may occur over the central High Plains and eastern Montana. ...High Plains... A mid/upper-level shortwave trough initially over the eastern Great Basin will take on a negative tilt as it advances towards the northern High Plains. Deep lee cyclogenesis is expected over far northeast WY/southeast MT, with a warm front arcing east across parts of the Dakotas. This low will advance north then northwestward across eastern MT through 12Z Wednesday. Large-scale ascent will be pronounced within this synoptic regime, with favorable upper-level difluence, mid-level height falls, and low-level convergence. However, weak buoyancy and modest mid-level lapse rates will characterize much of the environment to the south of the surface cyclone and warm front. Aided by a subtropical moisture plume over the Southwest, morning convection near the Four Corners region should move across the higher terrain and expand in coverage into the afternoon. High-based storms over the central and southern High Plains will progress into a well-mixed boundary layer that may initially be devoid of appreciable CAPE. This lack of greater buoyancy during the late afternoon to early evening (outside of areas north of the warm front) yields some uncertainty regarding the degree of storm intensity into the lower elevations. But with scattered to eventually widespread convection expected with time, extensive outflows are expected to push east. The most likely corridor for severe gusts appears to be over the central High Plains where the most pronounced 700-500 mb flow should advance ahead of the negative-tilt shortwave trough. Farther south, a few supercells may initially develop from parts of NM into southeast CO. Modest mid-level lapse rates should temper updraft vigor, but marginally severe hail along with isolated severe gusts will be possible. More favorable low-level moisture with steep mid-level lapse rates will reside near/north of the warm front, supporting moderate buoyancy from northeast MT into ND. While stronger ascent and deep-layer flow may not impinge upon areas north of the front until near sunset, organized storms should develop over the higher terrain by late afternoon and spread north within a backed mid-level flow regime. A few supercells along with an organized cluster or two may impinge on the greater downstream buoyancy plume, maintaining threats for large hail and severe gusts into Tuesday night. ...Eastern NC and southeast VA... While confidence is modest with the probable inland evolution of PTC 8, the bulk signal across guidance is for a weakening low-level wind field by Tuesday morning across the NC/VA coastal plain. The potential for low-topped supercells capable of brief tornadoes appears too low beyond 12Z Tuesday to warrant a risk highlight. ..Grams.. 09/16/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Mon Sep 16 2024 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE CENTRAL HIGH PLAINS AND EASTERN MT... ...SUMMARY... Isolated to scattered severe gusts and hail are possible Tuesday across a large swath of the High Plains region, mainly from late afternoon into the evening. The greater concentrations of severe storms may occur over the central High Plains and eastern Montana. ...High Plains... A mid/upper-level shortwave trough initially over the eastern Great Basin will take on a negative tilt as it advances towards the northern High Plains. Deep lee cyclogenesis is expected over far northeast WY/southeast MT, with a warm front arcing east across parts of the Dakotas. This low will advance north then northwestward across eastern MT through 12Z Wednesday. Large-scale ascent will be pronounced within this synoptic regime, with favorable upper-level difluence, mid-level height falls, and low-level convergence. However, weak buoyancy and modest mid-level lapse rates will characterize much of the environment to the south of the surface cyclone and warm front. Aided by a subtropical moisture plume over the Southwest, morning convection near the Four Corners region should move across the higher terrain and expand in coverage into the afternoon. High-based storms over the central and southern High Plains will progress into a well-mixed boundary layer that may initially be devoid of appreciable CAPE. This lack of greater buoyancy during the late afternoon to early evening (outside of areas north of the warm front) yields some uncertainty regarding the degree of storm intensity into the lower elevations. But with scattered to eventually widespread convection expected with time, extensive outflows are expected to push east. The most likely corridor for severe gusts appears to be over the central High Plains where the most pronounced 700-500 mb flow should advance ahead of the negative-tilt shortwave trough. Farther south, a few supercells may initially develop from parts of NM into southeast CO. Modest mid-level lapse rates should temper updraft vigor, but marginally severe hail along with isolated severe gusts will be possible. More favorable low-level moisture with steep mid-level lapse rates will reside near/north of the warm front, supporting moderate buoyancy from northeast MT into ND. While stronger ascent and deep-layer flow may not impinge upon areas north of the front until near sunset, organized storms should develop over the higher terrain by late afternoon and spread north within a backed mid-level flow regime. A few supercells along with an organized cluster or two may impinge on the greater downstream buoyancy plume, maintaining threats for large hail and severe gusts into Tuesday night. ...Eastern NC and southeast VA... While confidence is modest with the probable inland evolution of PTC 8, the bulk signal across guidance is for a weakening low-level wind field by Tuesday morning across the NC/VA coastal plain. The potential for low-topped supercells capable of brief tornadoes appears too low beyond 12Z Tuesday to warrant a risk highlight. ..Grams.. 09/16/2024 Read more