Severe Storms

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0204 PM CDT Sun Sep 15 2024 Valid 161200Z - 171200Z The primary changes to the Day 2 Fire Weather Outlook were to add Elevated highlights to portions of the central High Plains. Surface lee troughing ahead of an approaching broad mid-level trough will encourage 15-20 mph sustained southerly surface winds over the central High Plains (particularly along the KS/CO border), in tandem with 20-25 percent RH. These surface meteorological conditions will overspread modestly dry fuels, warranting Elevated highlights in this region. Surface high pressure over the Northeast will encourage dry easterly surface flow across portions of Ohio and immediate surrounding areas tomorrow, where fuels are anomalously dry and highly supportive of wildfire spread. RH may drop into the 20-25 percent range over these fuels by afternoon peak heating. However, surface sustained wind speeds should be generally under 15 mph, precluding the addition of Elevated highlights this outlook. Nonetheless, given such dry fuels (with a severe to locally extreme drought in place), gusty conditions may support localized brush-fire growth in this regime. ..Squitieri.. 09/15/2024 .PREV DISCUSSION... /ISSUED 0150 AM CDT Sun Sep 15 2024/ ...Synopsis... A highly amplified midlevel trough, accompanied by strong deep-layer south-southwesterly flow, will overspread the Great Basin during the day. This will promote 20-30 mph sustained south-southwesterly surface winds (with higher gusts) across portions of the southern Great Basin. Despite cooling surface temperatures and increasing moisture/RH, diurnal heating should still contribute to a corridor of 15-20 percent RH amid the strong/gusty winds. Therefore, Elevated highlights are in place for the wind-driven fire-weather risk. ...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 0204 PM CDT Sun Sep 15 2024 Valid 161200Z - 171200Z The primary changes to the Day 2 Fire Weather Outlook were to add Elevated highlights to portions of the central High Plains. Surface lee troughing ahead of an approaching broad mid-level trough will encourage 15-20 mph sustained southerly surface winds over the central High Plains (particularly along the KS/CO border), in tandem with 20-25 percent RH. These surface meteorological conditions will overspread modestly dry fuels, warranting Elevated highlights in this region. Surface high pressure over the Northeast will encourage dry easterly surface flow across portions of Ohio and immediate surrounding areas tomorrow, where fuels are anomalously dry and highly supportive of wildfire spread. RH may drop into the 20-25 percent range over these fuels by afternoon peak heating. However, surface sustained wind speeds should be generally under 15 mph, precluding the addition of Elevated highlights this outlook. Nonetheless, given such dry fuels (with a severe to locally extreme drought in place), gusty conditions may support localized brush-fire growth in this regime. ..Squitieri.. 09/15/2024 .PREV DISCUSSION... /ISSUED 0150 AM CDT Sun Sep 15 2024/ ...Synopsis... A highly amplified midlevel trough, accompanied by strong deep-layer south-southwesterly flow, will overspread the Great Basin during the day. This will promote 20-30 mph sustained south-southwesterly surface winds (with higher gusts) across portions of the southern Great Basin. Despite cooling surface temperatures and increasing moisture/RH, diurnal heating should still contribute to a corridor of 15-20 percent RH amid the strong/gusty winds. Therefore, Elevated highlights are in place for the wind-driven fire-weather risk. ...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 0204 PM CDT Sun Sep 15 2024 Valid 161200Z - 171200Z The primary changes to the Day 2 Fire Weather Outlook were to add Elevated highlights to portions of the central High Plains. Surface lee troughing ahead of an approaching broad mid-level trough will encourage 15-20 mph sustained southerly surface winds over the central High Plains (particularly along the KS/CO border), in tandem with 20-25 percent RH. These surface meteorological conditions will overspread modestly dry fuels, warranting Elevated highlights in this region. Surface high pressure over the Northeast will encourage dry easterly surface flow across portions of Ohio and immediate surrounding areas tomorrow, where fuels are anomalously dry and highly supportive of wildfire spread. RH may drop into the 20-25 percent range over these fuels by afternoon peak heating. However, surface sustained wind speeds should be generally under 15 mph, precluding the addition of Elevated highlights this outlook. Nonetheless, given such dry fuels (with a severe to locally extreme drought in place), gusty conditions may support localized brush-fire growth in this regime. ..Squitieri.. 09/15/2024 .PREV DISCUSSION... /ISSUED 0150 AM CDT Sun Sep 15 2024/ ...Synopsis... A highly amplified midlevel trough, accompanied by strong deep-layer south-southwesterly flow, will overspread the Great Basin during the day. This will promote 20-30 mph sustained south-southwesterly surface winds (with higher gusts) across portions of the southern Great Basin. Despite cooling surface temperatures and increasing moisture/RH, diurnal heating should still contribute to a corridor of 15-20 percent RH amid the strong/gusty winds. Therefore, Elevated highlights are in place for the wind-driven fire-weather risk. ...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 0204 PM CDT Sun Sep 15 2024 Valid 161200Z - 171200Z The primary changes to the Day 2 Fire Weather Outlook were to add Elevated highlights to portions of the central High Plains. Surface lee troughing ahead of an approaching broad mid-level trough will encourage 15-20 mph sustained southerly surface winds over the central High Plains (particularly along the KS/CO border), in tandem with 20-25 percent RH. These surface meteorological conditions will overspread modestly dry fuels, warranting Elevated highlights in this region. Surface high pressure over the Northeast will encourage dry easterly surface flow across portions of Ohio and immediate surrounding areas tomorrow, where fuels are anomalously dry and highly supportive of wildfire spread. RH may drop into the 20-25 percent range over these fuels by afternoon peak heating. However, surface sustained wind speeds should be generally under 15 mph, precluding the addition of Elevated highlights this outlook. Nonetheless, given such dry fuels (with a severe to locally extreme drought in place), gusty conditions may support localized brush-fire growth in this regime. ..Squitieri.. 09/15/2024 .PREV DISCUSSION... /ISSUED 0150 AM CDT Sun Sep 15 2024/ ...Synopsis... A highly amplified midlevel trough, accompanied by strong deep-layer south-southwesterly flow, will overspread the Great Basin during the day. This will promote 20-30 mph sustained south-southwesterly surface winds (with higher gusts) across portions of the southern Great Basin. Despite cooling surface temperatures and increasing moisture/RH, diurnal heating should still contribute to a corridor of 15-20 percent RH amid the strong/gusty winds. Therefore, Elevated highlights are in place for the wind-driven fire-weather risk. ...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 0204 PM CDT Sun Sep 15 2024 Valid 161200Z - 171200Z The primary changes to the Day 2 Fire Weather Outlook were to add Elevated highlights to portions of the central High Plains. Surface lee troughing ahead of an approaching broad mid-level trough will encourage 15-20 mph sustained southerly surface winds over the central High Plains (particularly along the KS/CO border), in tandem with 20-25 percent RH. These surface meteorological conditions will overspread modestly dry fuels, warranting Elevated highlights in this region. Surface high pressure over the Northeast will encourage dry easterly surface flow across portions of Ohio and immediate surrounding areas tomorrow, where fuels are anomalously dry and highly supportive of wildfire spread. RH may drop into the 20-25 percent range over these fuels by afternoon peak heating. However, surface sustained wind speeds should be generally under 15 mph, precluding the addition of Elevated highlights this outlook. Nonetheless, given such dry fuels (with a severe to locally extreme drought in place), gusty conditions may support localized brush-fire growth in this regime. ..Squitieri.. 09/15/2024 .PREV DISCUSSION... /ISSUED 0150 AM CDT Sun Sep 15 2024/ ...Synopsis... A highly amplified midlevel trough, accompanied by strong deep-layer south-southwesterly flow, will overspread the Great Basin during the day. This will promote 20-30 mph sustained south-southwesterly surface winds (with higher gusts) across portions of the southern Great Basin. Despite cooling surface temperatures and increasing moisture/RH, diurnal heating should still contribute to a corridor of 15-20 percent RH amid the strong/gusty winds. Therefore, Elevated highlights are in place for the wind-driven fire-weather risk. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Sun Sep 15 2024 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE EASTERN GREAT BASIN INTO THE FOUR CORNERS REGION...ND INTO NORTHWEST MN...EASTERN NC AND VICINITY... ...SUMMARY... On Monday, sporadic severe gusts and hail will be possible during the afternoon to early evening across parts of the eastern Great Basin to Four Corners. Isolated severe storms are possible over eastern North Dakota into northwest Minnesota. Some tornado threat may develop over eastern North Carolina and vicinity. ...Eastern Great Basin to the Four Corners... A seasonably strong mid-level low initially near San Francisco Bay Monday morning should move east during the day, before curling northeast Monday night towards the NV/UT/ID border area. This will occur in response to a strong mid-level jet translating through the basal portion of the large-scale trough across the Desert Southwest into the eastern Great Basin. Convection will likely be ongoing at the start of the forecast period near the midlevel low, and also farther east toward the Four Corners region, within the warm/moist conveyor. Relatively strong heating will be possible between these two regimes, from eastern NV into parts of UT. While buoyancy will likely remain quite weak within this warmer and more well-mixed regime, high-based convection will be possible during the afternoon and evening as the midlevel low approaches the region, with increasing meridional flow and a deeply mixed boundary layer supporting isolated severe gusts. Farther southeast into eastern UT and the Four Corners vicinity, increasing southwesterly flow aloft and strengthening deep-layer shear will become conditionally supportive of organized convection. Warmer midlevel temperatures may limit buoyancy to some extent, though sufficient moisture will support afternoon MLCAPE of 500-1000 J/kg. A few supercells will be possible within this regime, with an attendant threat of isolated severe gusts and hail. ...Parts of ND into northern MN... With the primary upper-level trough displaced well to the west, deep-layer shear will remain weak across much of the Great Plains. However, most guidance suggests an MCV will emanate out of central High Plains convection on D1/Sunday and gradually progress northeast towards the Red River Valley during the day on Monday. In conjunction with a strengthening low-level jet, this MCV may help to support relatively vigorous storm redevelopment within a moderately unstable environment during the afternoon and evening. Stronger midlevel flow attendant to the MCV could support some storm organization, and a couple supercells and/or stronger clusters will be possible, with a threat of isolated hail and damaging wind. Somewhat favorable low-level shear/SRH could also support a tornado threat, if a surface-based supercell can be sustained. Uncertainty remains regarding the strength/timing of any MCV moving across the region, along with the most favored corridor for diurnal storm development. ...Eastern NC and vicinity... Guidance generally suggests that an initially offshore surface low will move northward or northwestward from later on D1/Sunday into D2/Monday and D3/Tuesday, and eventually move inland across some part of the Carolinas. However, uncertainty remains regarding the timing, track, and intensity of this low, along with the extent to which it acquires any tropical or subtropical characteristics. If a deepening low does move onshore, then a higher theta-e airmass may move inland, accompanied by increasing low-level shear/SRH along/north of the low track. While the general scenario supports some potential for low-topped supercells, the magnitude of any tornado threat will be dependent on the extent of intensification that occurs with the low (and its attendant wind fields) prior to landfall. The Marginal Risk has been expanded somewhat across eastern NC and vicinity, in response to the various uncertainties. ..Dean.. 09/15/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Sun Sep 15 2024 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE EASTERN GREAT BASIN INTO THE FOUR CORNERS REGION...ND INTO NORTHWEST MN...EASTERN NC AND VICINITY... ...SUMMARY... On Monday, sporadic severe gusts and hail will be possible during the afternoon to early evening across parts of the eastern Great Basin to Four Corners. Isolated severe storms are possible over eastern North Dakota into northwest Minnesota. Some tornado threat may develop over eastern North Carolina and vicinity. ...Eastern Great Basin to the Four Corners... A seasonably strong mid-level low initially near San Francisco Bay Monday morning should move east during the day, before curling northeast Monday night towards the NV/UT/ID border area. This will occur in response to a strong mid-level jet translating through the basal portion of the large-scale trough across the Desert Southwest into the eastern Great Basin. Convection will likely be ongoing at the start of the forecast period near the midlevel low, and also farther east toward the Four Corners region, within the warm/moist conveyor. Relatively strong heating will be possible between these two regimes, from eastern NV into parts of UT. While buoyancy will likely remain quite weak within this warmer and more well-mixed regime, high-based convection will be possible during the afternoon and evening as the midlevel low approaches the region, with increasing meridional flow and a deeply mixed boundary layer supporting isolated severe gusts. Farther southeast into eastern UT and the Four Corners vicinity, increasing southwesterly flow aloft and strengthening deep-layer shear will become conditionally supportive of organized convection. Warmer midlevel temperatures may limit buoyancy to some extent, though sufficient moisture will support afternoon MLCAPE of 500-1000 J/kg. A few supercells will be possible within this regime, with an attendant threat of isolated severe gusts and hail. ...Parts of ND into northern MN... With the primary upper-level trough displaced well to the west, deep-layer shear will remain weak across much of the Great Plains. However, most guidance suggests an MCV will emanate out of central High Plains convection on D1/Sunday and gradually progress northeast towards the Red River Valley during the day on Monday. In conjunction with a strengthening low-level jet, this MCV may help to support relatively vigorous storm redevelopment within a moderately unstable environment during the afternoon and evening. Stronger midlevel flow attendant to the MCV could support some storm organization, and a couple supercells and/or stronger clusters will be possible, with a threat of isolated hail and damaging wind. Somewhat favorable low-level shear/SRH could also support a tornado threat, if a surface-based supercell can be sustained. Uncertainty remains regarding the strength/timing of any MCV moving across the region, along with the most favored corridor for diurnal storm development. ...Eastern NC and vicinity... Guidance generally suggests that an initially offshore surface low will move northward or northwestward from later on D1/Sunday into D2/Monday and D3/Tuesday, and eventually move inland across some part of the Carolinas. However, uncertainty remains regarding the timing, track, and intensity of this low, along with the extent to which it acquires any tropical or subtropical characteristics. If a deepening low does move onshore, then a higher theta-e airmass may move inland, accompanied by increasing low-level shear/SRH along/north of the low track. While the general scenario supports some potential for low-topped supercells, the magnitude of any tornado threat will be dependent on the extent of intensification that occurs with the low (and its attendant wind fields) prior to landfall. The Marginal Risk has been expanded somewhat across eastern NC and vicinity, in response to the various uncertainties. ..Dean.. 09/15/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Sun Sep 15 2024 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE EASTERN GREAT BASIN INTO THE FOUR CORNERS REGION...ND INTO NORTHWEST MN...EASTERN NC AND VICINITY... ...SUMMARY... On Monday, sporadic severe gusts and hail will be possible during the afternoon to early evening across parts of the eastern Great Basin to Four Corners. Isolated severe storms are possible over eastern North Dakota into northwest Minnesota. Some tornado threat may develop over eastern North Carolina and vicinity. ...Eastern Great Basin to the Four Corners... A seasonably strong mid-level low initially near San Francisco Bay Monday morning should move east during the day, before curling northeast Monday night towards the NV/UT/ID border area. This will occur in response to a strong mid-level jet translating through the basal portion of the large-scale trough across the Desert Southwest into the eastern Great Basin. Convection will likely be ongoing at the start of the forecast period near the midlevel low, and also farther east toward the Four Corners region, within the warm/moist conveyor. Relatively strong heating will be possible between these two regimes, from eastern NV into parts of UT. While buoyancy will likely remain quite weak within this warmer and more well-mixed regime, high-based convection will be possible during the afternoon and evening as the midlevel low approaches the region, with increasing meridional flow and a deeply mixed boundary layer supporting isolated severe gusts. Farther southeast into eastern UT and the Four Corners vicinity, increasing southwesterly flow aloft and strengthening deep-layer shear will become conditionally supportive of organized convection. Warmer midlevel temperatures may limit buoyancy to some extent, though sufficient moisture will support afternoon MLCAPE of 500-1000 J/kg. A few supercells will be possible within this regime, with an attendant threat of isolated severe gusts and hail. ...Parts of ND into northern MN... With the primary upper-level trough displaced well to the west, deep-layer shear will remain weak across much of the Great Plains. However, most guidance suggests an MCV will emanate out of central High Plains convection on D1/Sunday and gradually progress northeast towards the Red River Valley during the day on Monday. In conjunction with a strengthening low-level jet, this MCV may help to support relatively vigorous storm redevelopment within a moderately unstable environment during the afternoon and evening. Stronger midlevel flow attendant to the MCV could support some storm organization, and a couple supercells and/or stronger clusters will be possible, with a threat of isolated hail and damaging wind. Somewhat favorable low-level shear/SRH could also support a tornado threat, if a surface-based supercell can be sustained. Uncertainty remains regarding the strength/timing of any MCV moving across the region, along with the most favored corridor for diurnal storm development. ...Eastern NC and vicinity... Guidance generally suggests that an initially offshore surface low will move northward or northwestward from later on D1/Sunday into D2/Monday and D3/Tuesday, and eventually move inland across some part of the Carolinas. However, uncertainty remains regarding the timing, track, and intensity of this low, along with the extent to which it acquires any tropical or subtropical characteristics. If a deepening low does move onshore, then a higher theta-e airmass may move inland, accompanied by increasing low-level shear/SRH along/north of the low track. While the general scenario supports some potential for low-topped supercells, the magnitude of any tornado threat will be dependent on the extent of intensification that occurs with the low (and its attendant wind fields) prior to landfall. The Marginal Risk has been expanded somewhat across eastern NC and vicinity, in response to the various uncertainties. ..Dean.. 09/15/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Sun Sep 15 2024 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE EASTERN GREAT BASIN INTO THE FOUR CORNERS REGION...ND INTO NORTHWEST MN...EASTERN NC AND VICINITY... ...SUMMARY... On Monday, sporadic severe gusts and hail will be possible during the afternoon to early evening across parts of the eastern Great Basin to Four Corners. Isolated severe storms are possible over eastern North Dakota into northwest Minnesota. Some tornado threat may develop over eastern North Carolina and vicinity. ...Eastern Great Basin to the Four Corners... A seasonably strong mid-level low initially near San Francisco Bay Monday morning should move east during the day, before curling northeast Monday night towards the NV/UT/ID border area. This will occur in response to a strong mid-level jet translating through the basal portion of the large-scale trough across the Desert Southwest into the eastern Great Basin. Convection will likely be ongoing at the start of the forecast period near the midlevel low, and also farther east toward the Four Corners region, within the warm/moist conveyor. Relatively strong heating will be possible between these two regimes, from eastern NV into parts of UT. While buoyancy will likely remain quite weak within this warmer and more well-mixed regime, high-based convection will be possible during the afternoon and evening as the midlevel low approaches the region, with increasing meridional flow and a deeply mixed boundary layer supporting isolated severe gusts. Farther southeast into eastern UT and the Four Corners vicinity, increasing southwesterly flow aloft and strengthening deep-layer shear will become conditionally supportive of organized convection. Warmer midlevel temperatures may limit buoyancy to some extent, though sufficient moisture will support afternoon MLCAPE of 500-1000 J/kg. A few supercells will be possible within this regime, with an attendant threat of isolated severe gusts and hail. ...Parts of ND into northern MN... With the primary upper-level trough displaced well to the west, deep-layer shear will remain weak across much of the Great Plains. However, most guidance suggests an MCV will emanate out of central High Plains convection on D1/Sunday and gradually progress northeast towards the Red River Valley during the day on Monday. In conjunction with a strengthening low-level jet, this MCV may help to support relatively vigorous storm redevelopment within a moderately unstable environment during the afternoon and evening. Stronger midlevel flow attendant to the MCV could support some storm organization, and a couple supercells and/or stronger clusters will be possible, with a threat of isolated hail and damaging wind. Somewhat favorable low-level shear/SRH could also support a tornado threat, if a surface-based supercell can be sustained. Uncertainty remains regarding the strength/timing of any MCV moving across the region, along with the most favored corridor for diurnal storm development. ...Eastern NC and vicinity... Guidance generally suggests that an initially offshore surface low will move northward or northwestward from later on D1/Sunday into D2/Monday and D3/Tuesday, and eventually move inland across some part of the Carolinas. However, uncertainty remains regarding the timing, track, and intensity of this low, along with the extent to which it acquires any tropical or subtropical characteristics. If a deepening low does move onshore, then a higher theta-e airmass may move inland, accompanied by increasing low-level shear/SRH along/north of the low track. While the general scenario supports some potential for low-topped supercells, the magnitude of any tornado threat will be dependent on the extent of intensification that occurs with the low (and its attendant wind fields) prior to landfall. The Marginal Risk has been expanded somewhat across eastern NC and vicinity, in response to the various uncertainties. ..Dean.. 09/15/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Sun Sep 15 2024 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE EASTERN GREAT BASIN INTO THE FOUR CORNERS REGION...ND INTO NORTHWEST MN...EASTERN NC AND VICINITY... ...SUMMARY... On Monday, sporadic severe gusts and hail will be possible during the afternoon to early evening across parts of the eastern Great Basin to Four Corners. Isolated severe storms are possible over eastern North Dakota into northwest Minnesota. Some tornado threat may develop over eastern North Carolina and vicinity. ...Eastern Great Basin to the Four Corners... A seasonably strong mid-level low initially near San Francisco Bay Monday morning should move east during the day, before curling northeast Monday night towards the NV/UT/ID border area. This will occur in response to a strong mid-level jet translating through the basal portion of the large-scale trough across the Desert Southwest into the eastern Great Basin. Convection will likely be ongoing at the start of the forecast period near the midlevel low, and also farther east toward the Four Corners region, within the warm/moist conveyor. Relatively strong heating will be possible between these two regimes, from eastern NV into parts of UT. While buoyancy will likely remain quite weak within this warmer and more well-mixed regime, high-based convection will be possible during the afternoon and evening as the midlevel low approaches the region, with increasing meridional flow and a deeply mixed boundary layer supporting isolated severe gusts. Farther southeast into eastern UT and the Four Corners vicinity, increasing southwesterly flow aloft and strengthening deep-layer shear will become conditionally supportive of organized convection. Warmer midlevel temperatures may limit buoyancy to some extent, though sufficient moisture will support afternoon MLCAPE of 500-1000 J/kg. A few supercells will be possible within this regime, with an attendant threat of isolated severe gusts and hail. ...Parts of ND into northern MN... With the primary upper-level trough displaced well to the west, deep-layer shear will remain weak across much of the Great Plains. However, most guidance suggests an MCV will emanate out of central High Plains convection on D1/Sunday and gradually progress northeast towards the Red River Valley during the day on Monday. In conjunction with a strengthening low-level jet, this MCV may help to support relatively vigorous storm redevelopment within a moderately unstable environment during the afternoon and evening. Stronger midlevel flow attendant to the MCV could support some storm organization, and a couple supercells and/or stronger clusters will be possible, with a threat of isolated hail and damaging wind. Somewhat favorable low-level shear/SRH could also support a tornado threat, if a surface-based supercell can be sustained. Uncertainty remains regarding the strength/timing of any MCV moving across the region, along with the most favored corridor for diurnal storm development. ...Eastern NC and vicinity... Guidance generally suggests that an initially offshore surface low will move northward or northwestward from later on D1/Sunday into D2/Monday and D3/Tuesday, and eventually move inland across some part of the Carolinas. However, uncertainty remains regarding the timing, track, and intensity of this low, along with the extent to which it acquires any tropical or subtropical characteristics. If a deepening low does move onshore, then a higher theta-e airmass may move inland, accompanied by increasing low-level shear/SRH along/north of the low track. While the general scenario supports some potential for low-topped supercells, the magnitude of any tornado threat will be dependent on the extent of intensification that occurs with the low (and its attendant wind fields) prior to landfall. The Marginal Risk has been expanded somewhat across eastern NC and vicinity, in response to the various uncertainties. ..Dean.. 09/15/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Sun Sep 15 2024 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE EASTERN GREAT BASIN INTO THE FOUR CORNERS REGION...ND INTO NORTHWEST MN...EASTERN NC AND VICINITY... ...SUMMARY... On Monday, sporadic severe gusts and hail will be possible during the afternoon to early evening across parts of the eastern Great Basin to Four Corners. Isolated severe storms are possible over eastern North Dakota into northwest Minnesota. Some tornado threat may develop over eastern North Carolina and vicinity. ...Eastern Great Basin to the Four Corners... A seasonably strong mid-level low initially near San Francisco Bay Monday morning should move east during the day, before curling northeast Monday night towards the NV/UT/ID border area. This will occur in response to a strong mid-level jet translating through the basal portion of the large-scale trough across the Desert Southwest into the eastern Great Basin. Convection will likely be ongoing at the start of the forecast period near the midlevel low, and also farther east toward the Four Corners region, within the warm/moist conveyor. Relatively strong heating will be possible between these two regimes, from eastern NV into parts of UT. While buoyancy will likely remain quite weak within this warmer and more well-mixed regime, high-based convection will be possible during the afternoon and evening as the midlevel low approaches the region, with increasing meridional flow and a deeply mixed boundary layer supporting isolated severe gusts. Farther southeast into eastern UT and the Four Corners vicinity, increasing southwesterly flow aloft and strengthening deep-layer shear will become conditionally supportive of organized convection. Warmer midlevel temperatures may limit buoyancy to some extent, though sufficient moisture will support afternoon MLCAPE of 500-1000 J/kg. A few supercells will be possible within this regime, with an attendant threat of isolated severe gusts and hail. ...Parts of ND into northern MN... With the primary upper-level trough displaced well to the west, deep-layer shear will remain weak across much of the Great Plains. However, most guidance suggests an MCV will emanate out of central High Plains convection on D1/Sunday and gradually progress northeast towards the Red River Valley during the day on Monday. In conjunction with a strengthening low-level jet, this MCV may help to support relatively vigorous storm redevelopment within a moderately unstable environment during the afternoon and evening. Stronger midlevel flow attendant to the MCV could support some storm organization, and a couple supercells and/or stronger clusters will be possible, with a threat of isolated hail and damaging wind. Somewhat favorable low-level shear/SRH could also support a tornado threat, if a surface-based supercell can be sustained. Uncertainty remains regarding the strength/timing of any MCV moving across the region, along with the most favored corridor for diurnal storm development. ...Eastern NC and vicinity... Guidance generally suggests that an initially offshore surface low will move northward or northwestward from later on D1/Sunday into D2/Monday and D3/Tuesday, and eventually move inland across some part of the Carolinas. However, uncertainty remains regarding the timing, track, and intensity of this low, along with the extent to which it acquires any tropical or subtropical characteristics. If a deepening low does move onshore, then a higher theta-e airmass may move inland, accompanied by increasing low-level shear/SRH along/north of the low track. While the general scenario supports some potential for low-topped supercells, the magnitude of any tornado threat will be dependent on the extent of intensification that occurs with the low (and its attendant wind fields) prior to landfall. The Marginal Risk has been expanded somewhat across eastern NC and vicinity, in response to the various uncertainties. ..Dean.. 09/15/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Sun Sep 15 2024 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE EASTERN GREAT BASIN INTO THE FOUR CORNERS REGION...ND INTO NORTHWEST MN...EASTERN NC AND VICINITY... ...SUMMARY... On Monday, sporadic severe gusts and hail will be possible during the afternoon to early evening across parts of the eastern Great Basin to Four Corners. Isolated severe storms are possible over eastern North Dakota into northwest Minnesota. Some tornado threat may develop over eastern North Carolina and vicinity. ...Eastern Great Basin to the Four Corners... A seasonably strong mid-level low initially near San Francisco Bay Monday morning should move east during the day, before curling northeast Monday night towards the NV/UT/ID border area. This will occur in response to a strong mid-level jet translating through the basal portion of the large-scale trough across the Desert Southwest into the eastern Great Basin. Convection will likely be ongoing at the start of the forecast period near the midlevel low, and also farther east toward the Four Corners region, within the warm/moist conveyor. Relatively strong heating will be possible between these two regimes, from eastern NV into parts of UT. While buoyancy will likely remain quite weak within this warmer and more well-mixed regime, high-based convection will be possible during the afternoon and evening as the midlevel low approaches the region, with increasing meridional flow and a deeply mixed boundary layer supporting isolated severe gusts. Farther southeast into eastern UT and the Four Corners vicinity, increasing southwesterly flow aloft and strengthening deep-layer shear will become conditionally supportive of organized convection. Warmer midlevel temperatures may limit buoyancy to some extent, though sufficient moisture will support afternoon MLCAPE of 500-1000 J/kg. A few supercells will be possible within this regime, with an attendant threat of isolated severe gusts and hail. ...Parts of ND into northern MN... With the primary upper-level trough displaced well to the west, deep-layer shear will remain weak across much of the Great Plains. However, most guidance suggests an MCV will emanate out of central High Plains convection on D1/Sunday and gradually progress northeast towards the Red River Valley during the day on Monday. In conjunction with a strengthening low-level jet, this MCV may help to support relatively vigorous storm redevelopment within a moderately unstable environment during the afternoon and evening. Stronger midlevel flow attendant to the MCV could support some storm organization, and a couple supercells and/or stronger clusters will be possible, with a threat of isolated hail and damaging wind. Somewhat favorable low-level shear/SRH could also support a tornado threat, if a surface-based supercell can be sustained. Uncertainty remains regarding the strength/timing of any MCV moving across the region, along with the most favored corridor for diurnal storm development. ...Eastern NC and vicinity... Guidance generally suggests that an initially offshore surface low will move northward or northwestward from later on D1/Sunday into D2/Monday and D3/Tuesday, and eventually move inland across some part of the Carolinas. However, uncertainty remains regarding the timing, track, and intensity of this low, along with the extent to which it acquires any tropical or subtropical characteristics. If a deepening low does move onshore, then a higher theta-e airmass may move inland, accompanied by increasing low-level shear/SRH along/north of the low track. While the general scenario supports some potential for low-topped supercells, the magnitude of any tornado threat will be dependent on the extent of intensification that occurs with the low (and its attendant wind fields) prior to landfall. The Marginal Risk has been expanded somewhat across eastern NC and vicinity, in response to the various uncertainties. ..Dean.. 09/15/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Sun Sep 15 2024 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE EASTERN GREAT BASIN INTO THE FOUR CORNERS REGION...ND INTO NORTHWEST MN...EASTERN NC AND VICINITY... ...SUMMARY... On Monday, sporadic severe gusts and hail will be possible during the afternoon to early evening across parts of the eastern Great Basin to Four Corners. Isolated severe storms are possible over eastern North Dakota into northwest Minnesota. Some tornado threat may develop over eastern North Carolina and vicinity. ...Eastern Great Basin to the Four Corners... A seasonably strong mid-level low initially near San Francisco Bay Monday morning should move east during the day, before curling northeast Monday night towards the NV/UT/ID border area. This will occur in response to a strong mid-level jet translating through the basal portion of the large-scale trough across the Desert Southwest into the eastern Great Basin. Convection will likely be ongoing at the start of the forecast period near the midlevel low, and also farther east toward the Four Corners region, within the warm/moist conveyor. Relatively strong heating will be possible between these two regimes, from eastern NV into parts of UT. While buoyancy will likely remain quite weak within this warmer and more well-mixed regime, high-based convection will be possible during the afternoon and evening as the midlevel low approaches the region, with increasing meridional flow and a deeply mixed boundary layer supporting isolated severe gusts. Farther southeast into eastern UT and the Four Corners vicinity, increasing southwesterly flow aloft and strengthening deep-layer shear will become conditionally supportive of organized convection. Warmer midlevel temperatures may limit buoyancy to some extent, though sufficient moisture will support afternoon MLCAPE of 500-1000 J/kg. A few supercells will be possible within this regime, with an attendant threat of isolated severe gusts and hail. ...Parts of ND into northern MN... With the primary upper-level trough displaced well to the west, deep-layer shear will remain weak across much of the Great Plains. However, most guidance suggests an MCV will emanate out of central High Plains convection on D1/Sunday and gradually progress northeast towards the Red River Valley during the day on Monday. In conjunction with a strengthening low-level jet, this MCV may help to support relatively vigorous storm redevelopment within a moderately unstable environment during the afternoon and evening. Stronger midlevel flow attendant to the MCV could support some storm organization, and a couple supercells and/or stronger clusters will be possible, with a threat of isolated hail and damaging wind. Somewhat favorable low-level shear/SRH could also support a tornado threat, if a surface-based supercell can be sustained. Uncertainty remains regarding the strength/timing of any MCV moving across the region, along with the most favored corridor for diurnal storm development. ...Eastern NC and vicinity... Guidance generally suggests that an initially offshore surface low will move northward or northwestward from later on D1/Sunday into D2/Monday and D3/Tuesday, and eventually move inland across some part of the Carolinas. However, uncertainty remains regarding the timing, track, and intensity of this low, along with the extent to which it acquires any tropical or subtropical characteristics. If a deepening low does move onshore, then a higher theta-e airmass may move inland, accompanied by increasing low-level shear/SRH along/north of the low track. While the general scenario supports some potential for low-topped supercells, the magnitude of any tornado threat will be dependent on the extent of intensification that occurs with the low (and its attendant wind fields) prior to landfall. The Marginal Risk has been expanded somewhat across eastern NC and vicinity, in response to the various uncertainties. ..Dean.. 09/15/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Sun Sep 15 2024 Valid 151630Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail may occur today and tonight across parts of the northern/central Plains. ...Northern/Central Plains... An amplified upper trough along/near the West Coast this morning will further evolve into a closed upper low over northern CA and vicinity by late tonight. Ahead of this feature, modestly enhanced south-southwesterly mid-level flow will be in place over much of the western states and Rockies through the period. Although low-level moisture is expected to remain limited over much of this region, isolated strong to severe gusts may occur with any thunderstorms that can develop in a deeply mixed boundary layer favorable for gusty downdraft winds. Latest guidance continues to suggest that a relatively greater concentration of severe potential will be focused across parts of the northern/central Plains late this afternoon through tonight. Across this area, a weak surface lee trough and greater low-level moisture to its east should support weak to moderate instability with daytime heating. Steep mid-level lapse rates should also aid updraft accelerations/intensities, with around 20-30 kt of deep-layer shear supporting modest thunderstorm organization. Isolated severe hail may occur with initially more discrete convection, but a tendency for clustering should lead to a relatively greater wind threat with time as convection spreads generally east-northeastward through the evening. Regardless, the overall severe threat from northeast CO into western NE/SD and vicinity should remain fairly isolated/marginal given the modest deep-layer shear. Low-level warm advection is forecast to increase across much of the northern/central Plains tonight as a southerly low-level jet strengthens. A surface warm front is also expected to lift northward over ND late tonight into early Monday morning. With steepening mid-level lapse rates overspreading the northern Plains in tandem with increasing low-level moisture, ample MUCAPE should be available. Most guidance shows at least isolated convection developing across parts of ND tonight in this favorable thermodynamic environment. Although deep-layer shear may remain fairly modest, it may still be sufficient for updraft organization and an isolated threat for severe hail with any elevated convection that can form. Have therefore expanded the Marginal Risk northward to account for this potential. ...Coastal Carolinas... Latest NHC forecast continues to indicate some potential for sub-tropical or tropical development of a surface low currently off the SC Coast. Regardless of development, it still appears that the more moist/tropical low-level airmass over the Gulf Stream will struggle to advance inland over coastal portions of NC/SC through the end of the Day 1 forecast period early Monday morning (16/12Z). Accordingly, tornado potential with any low-topped supercells on the north to northeast periphery of the surface low should tend to remain offshore until Day 2/Monday (after 16/12Z). ..Gleason/Moore.. 09/15/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Sun Sep 15 2024 Valid 151630Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail may occur today and tonight across parts of the northern/central Plains. ...Northern/Central Plains... An amplified upper trough along/near the West Coast this morning will further evolve into a closed upper low over northern CA and vicinity by late tonight. Ahead of this feature, modestly enhanced south-southwesterly mid-level flow will be in place over much of the western states and Rockies through the period. Although low-level moisture is expected to remain limited over much of this region, isolated strong to severe gusts may occur with any thunderstorms that can develop in a deeply mixed boundary layer favorable for gusty downdraft winds. Latest guidance continues to suggest that a relatively greater concentration of severe potential will be focused across parts of the northern/central Plains late this afternoon through tonight. Across this area, a weak surface lee trough and greater low-level moisture to its east should support weak to moderate instability with daytime heating. Steep mid-level lapse rates should also aid updraft accelerations/intensities, with around 20-30 kt of deep-layer shear supporting modest thunderstorm organization. Isolated severe hail may occur with initially more discrete convection, but a tendency for clustering should lead to a relatively greater wind threat with time as convection spreads generally east-northeastward through the evening. Regardless, the overall severe threat from northeast CO into western NE/SD and vicinity should remain fairly isolated/marginal given the modest deep-layer shear. Low-level warm advection is forecast to increase across much of the northern/central Plains tonight as a southerly low-level jet strengthens. A surface warm front is also expected to lift northward over ND late tonight into early Monday morning. With steepening mid-level lapse rates overspreading the northern Plains in tandem with increasing low-level moisture, ample MUCAPE should be available. Most guidance shows at least isolated convection developing across parts of ND tonight in this favorable thermodynamic environment. Although deep-layer shear may remain fairly modest, it may still be sufficient for updraft organization and an isolated threat for severe hail with any elevated convection that can form. Have therefore expanded the Marginal Risk northward to account for this potential. ...Coastal Carolinas... Latest NHC forecast continues to indicate some potential for sub-tropical or tropical development of a surface low currently off the SC Coast. Regardless of development, it still appears that the more moist/tropical low-level airmass over the Gulf Stream will struggle to advance inland over coastal portions of NC/SC through the end of the Day 1 forecast period early Monday morning (16/12Z). Accordingly, tornado potential with any low-topped supercells on the north to northeast periphery of the surface low should tend to remain offshore until Day 2/Monday (after 16/12Z). ..Gleason/Moore.. 09/15/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Sun Sep 15 2024 Valid 151630Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail may occur today and tonight across parts of the northern/central Plains. ...Northern/Central Plains... An amplified upper trough along/near the West Coast this morning will further evolve into a closed upper low over northern CA and vicinity by late tonight. Ahead of this feature, modestly enhanced south-southwesterly mid-level flow will be in place over much of the western states and Rockies through the period. Although low-level moisture is expected to remain limited over much of this region, isolated strong to severe gusts may occur with any thunderstorms that can develop in a deeply mixed boundary layer favorable for gusty downdraft winds. Latest guidance continues to suggest that a relatively greater concentration of severe potential will be focused across parts of the northern/central Plains late this afternoon through tonight. Across this area, a weak surface lee trough and greater low-level moisture to its east should support weak to moderate instability with daytime heating. Steep mid-level lapse rates should also aid updraft accelerations/intensities, with around 20-30 kt of deep-layer shear supporting modest thunderstorm organization. Isolated severe hail may occur with initially more discrete convection, but a tendency for clustering should lead to a relatively greater wind threat with time as convection spreads generally east-northeastward through the evening. Regardless, the overall severe threat from northeast CO into western NE/SD and vicinity should remain fairly isolated/marginal given the modest deep-layer shear. Low-level warm advection is forecast to increase across much of the northern/central Plains tonight as a southerly low-level jet strengthens. A surface warm front is also expected to lift northward over ND late tonight into early Monday morning. With steepening mid-level lapse rates overspreading the northern Plains in tandem with increasing low-level moisture, ample MUCAPE should be available. Most guidance shows at least isolated convection developing across parts of ND tonight in this favorable thermodynamic environment. Although deep-layer shear may remain fairly modest, it may still be sufficient for updraft organization and an isolated threat for severe hail with any elevated convection that can form. Have therefore expanded the Marginal Risk northward to account for this potential. ...Coastal Carolinas... Latest NHC forecast continues to indicate some potential for sub-tropical or tropical development of a surface low currently off the SC Coast. Regardless of development, it still appears that the more moist/tropical low-level airmass over the Gulf Stream will struggle to advance inland over coastal portions of NC/SC through the end of the Day 1 forecast period early Monday morning (16/12Z). Accordingly, tornado potential with any low-topped supercells on the north to northeast periphery of the surface low should tend to remain offshore until Day 2/Monday (after 16/12Z). ..Gleason/Moore.. 09/15/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Sun Sep 15 2024 Valid 151630Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail may occur today and tonight across parts of the northern/central Plains. ...Northern/Central Plains... An amplified upper trough along/near the West Coast this morning will further evolve into a closed upper low over northern CA and vicinity by late tonight. Ahead of this feature, modestly enhanced south-southwesterly mid-level flow will be in place over much of the western states and Rockies through the period. Although low-level moisture is expected to remain limited over much of this region, isolated strong to severe gusts may occur with any thunderstorms that can develop in a deeply mixed boundary layer favorable for gusty downdraft winds. Latest guidance continues to suggest that a relatively greater concentration of severe potential will be focused across parts of the northern/central Plains late this afternoon through tonight. Across this area, a weak surface lee trough and greater low-level moisture to its east should support weak to moderate instability with daytime heating. Steep mid-level lapse rates should also aid updraft accelerations/intensities, with around 20-30 kt of deep-layer shear supporting modest thunderstorm organization. Isolated severe hail may occur with initially more discrete convection, but a tendency for clustering should lead to a relatively greater wind threat with time as convection spreads generally east-northeastward through the evening. Regardless, the overall severe threat from northeast CO into western NE/SD and vicinity should remain fairly isolated/marginal given the modest deep-layer shear. Low-level warm advection is forecast to increase across much of the northern/central Plains tonight as a southerly low-level jet strengthens. A surface warm front is also expected to lift northward over ND late tonight into early Monday morning. With steepening mid-level lapse rates overspreading the northern Plains in tandem with increasing low-level moisture, ample MUCAPE should be available. Most guidance shows at least isolated convection developing across parts of ND tonight in this favorable thermodynamic environment. Although deep-layer shear may remain fairly modest, it may still be sufficient for updraft organization and an isolated threat for severe hail with any elevated convection that can form. Have therefore expanded the Marginal Risk northward to account for this potential. ...Coastal Carolinas... Latest NHC forecast continues to indicate some potential for sub-tropical or tropical development of a surface low currently off the SC Coast. Regardless of development, it still appears that the more moist/tropical low-level airmass over the Gulf Stream will struggle to advance inland over coastal portions of NC/SC through the end of the Day 1 forecast period early Monday morning (16/12Z). Accordingly, tornado potential with any low-topped supercells on the north to northeast periphery of the surface low should tend to remain offshore until Day 2/Monday (after 16/12Z). ..Gleason/Moore.. 09/15/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Sun Sep 15 2024 Valid 151630Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail may occur today and tonight across parts of the northern/central Plains. ...Northern/Central Plains... An amplified upper trough along/near the West Coast this morning will further evolve into a closed upper low over northern CA and vicinity by late tonight. Ahead of this feature, modestly enhanced south-southwesterly mid-level flow will be in place over much of the western states and Rockies through the period. Although low-level moisture is expected to remain limited over much of this region, isolated strong to severe gusts may occur with any thunderstorms that can develop in a deeply mixed boundary layer favorable for gusty downdraft winds. Latest guidance continues to suggest that a relatively greater concentration of severe potential will be focused across parts of the northern/central Plains late this afternoon through tonight. Across this area, a weak surface lee trough and greater low-level moisture to its east should support weak to moderate instability with daytime heating. Steep mid-level lapse rates should also aid updraft accelerations/intensities, with around 20-30 kt of deep-layer shear supporting modest thunderstorm organization. Isolated severe hail may occur with initially more discrete convection, but a tendency for clustering should lead to a relatively greater wind threat with time as convection spreads generally east-northeastward through the evening. Regardless, the overall severe threat from northeast CO into western NE/SD and vicinity should remain fairly isolated/marginal given the modest deep-layer shear. Low-level warm advection is forecast to increase across much of the northern/central Plains tonight as a southerly low-level jet strengthens. A surface warm front is also expected to lift northward over ND late tonight into early Monday morning. With steepening mid-level lapse rates overspreading the northern Plains in tandem with increasing low-level moisture, ample MUCAPE should be available. Most guidance shows at least isolated convection developing across parts of ND tonight in this favorable thermodynamic environment. Although deep-layer shear may remain fairly modest, it may still be sufficient for updraft organization and an isolated threat for severe hail with any elevated convection that can form. Have therefore expanded the Marginal Risk northward to account for this potential. ...Coastal Carolinas... Latest NHC forecast continues to indicate some potential for sub-tropical or tropical development of a surface low currently off the SC Coast. Regardless of development, it still appears that the more moist/tropical low-level airmass over the Gulf Stream will struggle to advance inland over coastal portions of NC/SC through the end of the Day 1 forecast period early Monday morning (16/12Z). Accordingly, tornado potential with any low-topped supercells on the north to northeast periphery of the surface low should tend to remain offshore until Day 2/Monday (after 16/12Z). ..Gleason/Moore.. 09/15/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Sun Sep 15 2024 Valid 151630Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail may occur today and tonight across parts of the northern/central Plains. ...Northern/Central Plains... An amplified upper trough along/near the West Coast this morning will further evolve into a closed upper low over northern CA and vicinity by late tonight. Ahead of this feature, modestly enhanced south-southwesterly mid-level flow will be in place over much of the western states and Rockies through the period. Although low-level moisture is expected to remain limited over much of this region, isolated strong to severe gusts may occur with any thunderstorms that can develop in a deeply mixed boundary layer favorable for gusty downdraft winds. Latest guidance continues to suggest that a relatively greater concentration of severe potential will be focused across parts of the northern/central Plains late this afternoon through tonight. Across this area, a weak surface lee trough and greater low-level moisture to its east should support weak to moderate instability with daytime heating. Steep mid-level lapse rates should also aid updraft accelerations/intensities, with around 20-30 kt of deep-layer shear supporting modest thunderstorm organization. Isolated severe hail may occur with initially more discrete convection, but a tendency for clustering should lead to a relatively greater wind threat with time as convection spreads generally east-northeastward through the evening. Regardless, the overall severe threat from northeast CO into western NE/SD and vicinity should remain fairly isolated/marginal given the modest deep-layer shear. Low-level warm advection is forecast to increase across much of the northern/central Plains tonight as a southerly low-level jet strengthens. A surface warm front is also expected to lift northward over ND late tonight into early Monday morning. With steepening mid-level lapse rates overspreading the northern Plains in tandem with increasing low-level moisture, ample MUCAPE should be available. Most guidance shows at least isolated convection developing across parts of ND tonight in this favorable thermodynamic environment. Although deep-layer shear may remain fairly modest, it may still be sufficient for updraft organization and an isolated threat for severe hail with any elevated convection that can form. Have therefore expanded the Marginal Risk northward to account for this potential. ...Coastal Carolinas... Latest NHC forecast continues to indicate some potential for sub-tropical or tropical development of a surface low currently off the SC Coast. Regardless of development, it still appears that the more moist/tropical low-level airmass over the Gulf Stream will struggle to advance inland over coastal portions of NC/SC through the end of the Day 1 forecast period early Monday morning (16/12Z). Accordingly, tornado potential with any low-topped supercells on the north to northeast periphery of the surface low should tend to remain offshore until Day 2/Monday (after 16/12Z). ..Gleason/Moore.. 09/15/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Sun Sep 15 2024 Valid 151630Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail may occur today and tonight across parts of the northern/central Plains. ...Northern/Central Plains... An amplified upper trough along/near the West Coast this morning will further evolve into a closed upper low over northern CA and vicinity by late tonight. Ahead of this feature, modestly enhanced south-southwesterly mid-level flow will be in place over much of the western states and Rockies through the period. Although low-level moisture is expected to remain limited over much of this region, isolated strong to severe gusts may occur with any thunderstorms that can develop in a deeply mixed boundary layer favorable for gusty downdraft winds. Latest guidance continues to suggest that a relatively greater concentration of severe potential will be focused across parts of the northern/central Plains late this afternoon through tonight. Across this area, a weak surface lee trough and greater low-level moisture to its east should support weak to moderate instability with daytime heating. Steep mid-level lapse rates should also aid updraft accelerations/intensities, with around 20-30 kt of deep-layer shear supporting modest thunderstorm organization. Isolated severe hail may occur with initially more discrete convection, but a tendency for clustering should lead to a relatively greater wind threat with time as convection spreads generally east-northeastward through the evening. Regardless, the overall severe threat from northeast CO into western NE/SD and vicinity should remain fairly isolated/marginal given the modest deep-layer shear. Low-level warm advection is forecast to increase across much of the northern/central Plains tonight as a southerly low-level jet strengthens. A surface warm front is also expected to lift northward over ND late tonight into early Monday morning. With steepening mid-level lapse rates overspreading the northern Plains in tandem with increasing low-level moisture, ample MUCAPE should be available. Most guidance shows at least isolated convection developing across parts of ND tonight in this favorable thermodynamic environment. Although deep-layer shear may remain fairly modest, it may still be sufficient for updraft organization and an isolated threat for severe hail with any elevated convection that can form. Have therefore expanded the Marginal Risk northward to account for this potential. ...Coastal Carolinas... Latest NHC forecast continues to indicate some potential for sub-tropical or tropical development of a surface low currently off the SC Coast. Regardless of development, it still appears that the more moist/tropical low-level airmass over the Gulf Stream will struggle to advance inland over coastal portions of NC/SC through the end of the Day 1 forecast period early Monday morning (16/12Z). Accordingly, tornado potential with any low-topped supercells on the north to northeast periphery of the surface low should tend to remain offshore until Day 2/Monday (after 16/12Z). ..Gleason/Moore.. 09/15/2024 Read more