Severe Storms

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1106 AM CDT Fri Jul 18 2025 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF VIRGINIA AND NORTH CAROLINA...AND WESTERN PARTS OF THE MIDWEST... ...SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a couple of tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ...Virginia/North Carolina to the Mid-South... Late morning surface analysis places a stationary front draped from west to east from the mid MS Valley eastward into the Mid-Atlantic states. Visible satellite/radar mosaic imagery shows a couple of weak MCVs moving east over the northern VA/MD vicinity and over far eastern KY. The latter disturbance will probably prove instrumental in aiding storm development across VA into northern NC this afternoon. South of the front, rich low-level moisture and heating will act to offset weak mid-level lapse rates and yield moderate to strong buoyancy from southeast MO eastward to the Mid-Atlantic coast. Early indications of a swelling cumulus field over the WV/VA mountains will gradually evolve into a cluster of storms as convective inhibition continues to erode through early afternoon. Other clusters of storms will develop and move west to east given marginal deep-layer mean westerly flow. Although small hail 0.50-1.00 inch in diameter is possible with the strongest cores, the primary hazard with the stronger storms will be damaging gusts (50-65 mph) with the more intense water-loaded downdrafts. This activity will likely diminish by the early to mid evening. ...South Dakota/Nebraska into Minnesota/Iowa... Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. An initially appreciable capping inversion will inhibit surface-based storm development until heating gradually weakens inhibition by late afternoon. A very unstable airmass is forecast by late afternoon/early evening, but nebulous forcing lends uncertainty in terms of storm development/timing. Models suggest storms will primarily develop this evening associated with strengthening low-level theta-e advection. Supercells are possible early in the convective life cycle with a risk for all hazards, including the possibility for a couple of tornadoes, but large hail may be the main hazard. Upscale growth into a cluster or MCS is possible near the terminus of a southwesterly 850-mb LLJ with severe gusts the becoming the primary threat. Models vary considerably whether storm intensity is maintained through much of the overnight and beyond the Day-1 period, or if a gradual diminishing in severe occurs. ...Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. Steep low/mid-level lapse rates and a deep, very well-mixed boundary layer should support isolated severe gusts with the stronger thunderstorms. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ..Smith/Weinman.. 07/18/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1106 AM CDT Fri Jul 18 2025 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF VIRGINIA AND NORTH CAROLINA...AND WESTERN PARTS OF THE MIDWEST... ...SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a couple of tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ...Virginia/North Carolina to the Mid-South... Late morning surface analysis places a stationary front draped from west to east from the mid MS Valley eastward into the Mid-Atlantic states. Visible satellite/radar mosaic imagery shows a couple of weak MCVs moving east over the northern VA/MD vicinity and over far eastern KY. The latter disturbance will probably prove instrumental in aiding storm development across VA into northern NC this afternoon. South of the front, rich low-level moisture and heating will act to offset weak mid-level lapse rates and yield moderate to strong buoyancy from southeast MO eastward to the Mid-Atlantic coast. Early indications of a swelling cumulus field over the WV/VA mountains will gradually evolve into a cluster of storms as convective inhibition continues to erode through early afternoon. Other clusters of storms will develop and move west to east given marginal deep-layer mean westerly flow. Although small hail 0.50-1.00 inch in diameter is possible with the strongest cores, the primary hazard with the stronger storms will be damaging gusts (50-65 mph) with the more intense water-loaded downdrafts. This activity will likely diminish by the early to mid evening. ...South Dakota/Nebraska into Minnesota/Iowa... Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. An initially appreciable capping inversion will inhibit surface-based storm development until heating gradually weakens inhibition by late afternoon. A very unstable airmass is forecast by late afternoon/early evening, but nebulous forcing lends uncertainty in terms of storm development/timing. Models suggest storms will primarily develop this evening associated with strengthening low-level theta-e advection. Supercells are possible early in the convective life cycle with a risk for all hazards, including the possibility for a couple of tornadoes, but large hail may be the main hazard. Upscale growth into a cluster or MCS is possible near the terminus of a southwesterly 850-mb LLJ with severe gusts the becoming the primary threat. Models vary considerably whether storm intensity is maintained through much of the overnight and beyond the Day-1 period, or if a gradual diminishing in severe occurs. ...Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. Steep low/mid-level lapse rates and a deep, very well-mixed boundary layer should support isolated severe gusts with the stronger thunderstorms. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ..Smith/Weinman.. 07/18/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1106 AM CDT Fri Jul 18 2025 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF VIRGINIA AND NORTH CAROLINA...AND WESTERN PARTS OF THE MIDWEST... ...SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a couple of tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ...Virginia/North Carolina to the Mid-South... Late morning surface analysis places a stationary front draped from west to east from the mid MS Valley eastward into the Mid-Atlantic states. Visible satellite/radar mosaic imagery shows a couple of weak MCVs moving east over the northern VA/MD vicinity and over far eastern KY. The latter disturbance will probably prove instrumental in aiding storm development across VA into northern NC this afternoon. South of the front, rich low-level moisture and heating will act to offset weak mid-level lapse rates and yield moderate to strong buoyancy from southeast MO eastward to the Mid-Atlantic coast. Early indications of a swelling cumulus field over the WV/VA mountains will gradually evolve into a cluster of storms as convective inhibition continues to erode through early afternoon. Other clusters of storms will develop and move west to east given marginal deep-layer mean westerly flow. Although small hail 0.50-1.00 inch in diameter is possible with the strongest cores, the primary hazard with the stronger storms will be damaging gusts (50-65 mph) with the more intense water-loaded downdrafts. This activity will likely diminish by the early to mid evening. ...South Dakota/Nebraska into Minnesota/Iowa... Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. An initially appreciable capping inversion will inhibit surface-based storm development until heating gradually weakens inhibition by late afternoon. A very unstable airmass is forecast by late afternoon/early evening, but nebulous forcing lends uncertainty in terms of storm development/timing. Models suggest storms will primarily develop this evening associated with strengthening low-level theta-e advection. Supercells are possible early in the convective life cycle with a risk for all hazards, including the possibility for a couple of tornadoes, but large hail may be the main hazard. Upscale growth into a cluster or MCS is possible near the terminus of a southwesterly 850-mb LLJ with severe gusts the becoming the primary threat. Models vary considerably whether storm intensity is maintained through much of the overnight and beyond the Day-1 period, or if a gradual diminishing in severe occurs. ...Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. Steep low/mid-level lapse rates and a deep, very well-mixed boundary layer should support isolated severe gusts with the stronger thunderstorms. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ..Smith/Weinman.. 07/18/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1106 AM CDT Fri Jul 18 2025 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF VIRGINIA AND NORTH CAROLINA...AND WESTERN PARTS OF THE MIDWEST... ...SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a couple of tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ...Virginia/North Carolina to the Mid-South... Late morning surface analysis places a stationary front draped from west to east from the mid MS Valley eastward into the Mid-Atlantic states. Visible satellite/radar mosaic imagery shows a couple of weak MCVs moving east over the northern VA/MD vicinity and over far eastern KY. The latter disturbance will probably prove instrumental in aiding storm development across VA into northern NC this afternoon. South of the front, rich low-level moisture and heating will act to offset weak mid-level lapse rates and yield moderate to strong buoyancy from southeast MO eastward to the Mid-Atlantic coast. Early indications of a swelling cumulus field over the WV/VA mountains will gradually evolve into a cluster of storms as convective inhibition continues to erode through early afternoon. Other clusters of storms will develop and move west to east given marginal deep-layer mean westerly flow. Although small hail 0.50-1.00 inch in diameter is possible with the strongest cores, the primary hazard with the stronger storms will be damaging gusts (50-65 mph) with the more intense water-loaded downdrafts. This activity will likely diminish by the early to mid evening. ...South Dakota/Nebraska into Minnesota/Iowa... Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. An initially appreciable capping inversion will inhibit surface-based storm development until heating gradually weakens inhibition by late afternoon. A very unstable airmass is forecast by late afternoon/early evening, but nebulous forcing lends uncertainty in terms of storm development/timing. Models suggest storms will primarily develop this evening associated with strengthening low-level theta-e advection. Supercells are possible early in the convective life cycle with a risk for all hazards, including the possibility for a couple of tornadoes, but large hail may be the main hazard. Upscale growth into a cluster or MCS is possible near the terminus of a southwesterly 850-mb LLJ with severe gusts the becoming the primary threat. Models vary considerably whether storm intensity is maintained through much of the overnight and beyond the Day-1 period, or if a gradual diminishing in severe occurs. ...Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. Steep low/mid-level lapse rates and a deep, very well-mixed boundary layer should support isolated severe gusts with the stronger thunderstorms. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ..Smith/Weinman.. 07/18/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1106 AM CDT Fri Jul 18 2025 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF VIRGINIA AND NORTH CAROLINA...AND WESTERN PARTS OF THE MIDWEST... ...SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a couple of tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ...Virginia/North Carolina to the Mid-South... Late morning surface analysis places a stationary front draped from west to east from the mid MS Valley eastward into the Mid-Atlantic states. Visible satellite/radar mosaic imagery shows a couple of weak MCVs moving east over the northern VA/MD vicinity and over far eastern KY. The latter disturbance will probably prove instrumental in aiding storm development across VA into northern NC this afternoon. South of the front, rich low-level moisture and heating will act to offset weak mid-level lapse rates and yield moderate to strong buoyancy from southeast MO eastward to the Mid-Atlantic coast. Early indications of a swelling cumulus field over the WV/VA mountains will gradually evolve into a cluster of storms as convective inhibition continues to erode through early afternoon. Other clusters of storms will develop and move west to east given marginal deep-layer mean westerly flow. Although small hail 0.50-1.00 inch in diameter is possible with the strongest cores, the primary hazard with the stronger storms will be damaging gusts (50-65 mph) with the more intense water-loaded downdrafts. This activity will likely diminish by the early to mid evening. ...South Dakota/Nebraska into Minnesota/Iowa... Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. An initially appreciable capping inversion will inhibit surface-based storm development until heating gradually weakens inhibition by late afternoon. A very unstable airmass is forecast by late afternoon/early evening, but nebulous forcing lends uncertainty in terms of storm development/timing. Models suggest storms will primarily develop this evening associated with strengthening low-level theta-e advection. Supercells are possible early in the convective life cycle with a risk for all hazards, including the possibility for a couple of tornadoes, but large hail may be the main hazard. Upscale growth into a cluster or MCS is possible near the terminus of a southwesterly 850-mb LLJ with severe gusts the becoming the primary threat. Models vary considerably whether storm intensity is maintained through much of the overnight and beyond the Day-1 period, or if a gradual diminishing in severe occurs. ...Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. Steep low/mid-level lapse rates and a deep, very well-mixed boundary layer should support isolated severe gusts with the stronger thunderstorms. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ..Smith/Weinman.. 07/18/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1106 AM CDT Fri Jul 18 2025 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF VIRGINIA AND NORTH CAROLINA...AND WESTERN PARTS OF THE MIDWEST... ...SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a couple of tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ...Virginia/North Carolina to the Mid-South... Late morning surface analysis places a stationary front draped from west to east from the mid MS Valley eastward into the Mid-Atlantic states. Visible satellite/radar mosaic imagery shows a couple of weak MCVs moving east over the northern VA/MD vicinity and over far eastern KY. The latter disturbance will probably prove instrumental in aiding storm development across VA into northern NC this afternoon. South of the front, rich low-level moisture and heating will act to offset weak mid-level lapse rates and yield moderate to strong buoyancy from southeast MO eastward to the Mid-Atlantic coast. Early indications of a swelling cumulus field over the WV/VA mountains will gradually evolve into a cluster of storms as convective inhibition continues to erode through early afternoon. Other clusters of storms will develop and move west to east given marginal deep-layer mean westerly flow. Although small hail 0.50-1.00 inch in diameter is possible with the strongest cores, the primary hazard with the stronger storms will be damaging gusts (50-65 mph) with the more intense water-loaded downdrafts. This activity will likely diminish by the early to mid evening. ...South Dakota/Nebraska into Minnesota/Iowa... Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. An initially appreciable capping inversion will inhibit surface-based storm development until heating gradually weakens inhibition by late afternoon. A very unstable airmass is forecast by late afternoon/early evening, but nebulous forcing lends uncertainty in terms of storm development/timing. Models suggest storms will primarily develop this evening associated with strengthening low-level theta-e advection. Supercells are possible early in the convective life cycle with a risk for all hazards, including the possibility for a couple of tornadoes, but large hail may be the main hazard. Upscale growth into a cluster or MCS is possible near the terminus of a southwesterly 850-mb LLJ with severe gusts the becoming the primary threat. Models vary considerably whether storm intensity is maintained through much of the overnight and beyond the Day-1 period, or if a gradual diminishing in severe occurs. ...Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. Steep low/mid-level lapse rates and a deep, very well-mixed boundary layer should support isolated severe gusts with the stronger thunderstorms. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ..Smith/Weinman.. 07/18/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1106 AM CDT Fri Jul 18 2025 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF VIRGINIA AND NORTH CAROLINA...AND WESTERN PARTS OF THE MIDWEST... ...SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a couple of tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ...Virginia/North Carolina to the Mid-South... Late morning surface analysis places a stationary front draped from west to east from the mid MS Valley eastward into the Mid-Atlantic states. Visible satellite/radar mosaic imagery shows a couple of weak MCVs moving east over the northern VA/MD vicinity and over far eastern KY. The latter disturbance will probably prove instrumental in aiding storm development across VA into northern NC this afternoon. South of the front, rich low-level moisture and heating will act to offset weak mid-level lapse rates and yield moderate to strong buoyancy from southeast MO eastward to the Mid-Atlantic coast. Early indications of a swelling cumulus field over the WV/VA mountains will gradually evolve into a cluster of storms as convective inhibition continues to erode through early afternoon. Other clusters of storms will develop and move west to east given marginal deep-layer mean westerly flow. Although small hail 0.50-1.00 inch in diameter is possible with the strongest cores, the primary hazard with the stronger storms will be damaging gusts (50-65 mph) with the more intense water-loaded downdrafts. This activity will likely diminish by the early to mid evening. ...South Dakota/Nebraska into Minnesota/Iowa... Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. An initially appreciable capping inversion will inhibit surface-based storm development until heating gradually weakens inhibition by late afternoon. A very unstable airmass is forecast by late afternoon/early evening, but nebulous forcing lends uncertainty in terms of storm development/timing. Models suggest storms will primarily develop this evening associated with strengthening low-level theta-e advection. Supercells are possible early in the convective life cycle with a risk for all hazards, including the possibility for a couple of tornadoes, but large hail may be the main hazard. Upscale growth into a cluster or MCS is possible near the terminus of a southwesterly 850-mb LLJ with severe gusts the becoming the primary threat. Models vary considerably whether storm intensity is maintained through much of the overnight and beyond the Day-1 period, or if a gradual diminishing in severe occurs. ...Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. Steep low/mid-level lapse rates and a deep, very well-mixed boundary layer should support isolated severe gusts with the stronger thunderstorms. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ..Smith/Weinman.. 07/18/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1106 AM CDT Fri Jul 18 2025 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF VIRGINIA AND NORTH CAROLINA...AND WESTERN PARTS OF THE MIDWEST... ...SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a couple of tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ...Virginia/North Carolina to the Mid-South... Late morning surface analysis places a stationary front draped from west to east from the mid MS Valley eastward into the Mid-Atlantic states. Visible satellite/radar mosaic imagery shows a couple of weak MCVs moving east over the northern VA/MD vicinity and over far eastern KY. The latter disturbance will probably prove instrumental in aiding storm development across VA into northern NC this afternoon. South of the front, rich low-level moisture and heating will act to offset weak mid-level lapse rates and yield moderate to strong buoyancy from southeast MO eastward to the Mid-Atlantic coast. Early indications of a swelling cumulus field over the WV/VA mountains will gradually evolve into a cluster of storms as convective inhibition continues to erode through early afternoon. Other clusters of storms will develop and move west to east given marginal deep-layer mean westerly flow. Although small hail 0.50-1.00 inch in diameter is possible with the strongest cores, the primary hazard with the stronger storms will be damaging gusts (50-65 mph) with the more intense water-loaded downdrafts. This activity will likely diminish by the early to mid evening. ...South Dakota/Nebraska into Minnesota/Iowa... Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. An initially appreciable capping inversion will inhibit surface-based storm development until heating gradually weakens inhibition by late afternoon. A very unstable airmass is forecast by late afternoon/early evening, but nebulous forcing lends uncertainty in terms of storm development/timing. Models suggest storms will primarily develop this evening associated with strengthening low-level theta-e advection. Supercells are possible early in the convective life cycle with a risk for all hazards, including the possibility for a couple of tornadoes, but large hail may be the main hazard. Upscale growth into a cluster or MCS is possible near the terminus of a southwesterly 850-mb LLJ with severe gusts the becoming the primary threat. Models vary considerably whether storm intensity is maintained through much of the overnight and beyond the Day-1 period, or if a gradual diminishing in severe occurs. ...Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. Steep low/mid-level lapse rates and a deep, very well-mixed boundary layer should support isolated severe gusts with the stronger thunderstorms. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ..Smith/Weinman.. 07/18/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1106 AM CDT Fri Jul 18 2025 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF VIRGINIA AND NORTH CAROLINA...AND WESTERN PARTS OF THE MIDWEST... ...SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a couple of tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ...Virginia/North Carolina to the Mid-South... Late morning surface analysis places a stationary front draped from west to east from the mid MS Valley eastward into the Mid-Atlantic states. Visible satellite/radar mosaic imagery shows a couple of weak MCVs moving east over the northern VA/MD vicinity and over far eastern KY. The latter disturbance will probably prove instrumental in aiding storm development across VA into northern NC this afternoon. South of the front, rich low-level moisture and heating will act to offset weak mid-level lapse rates and yield moderate to strong buoyancy from southeast MO eastward to the Mid-Atlantic coast. Early indications of a swelling cumulus field over the WV/VA mountains will gradually evolve into a cluster of storms as convective inhibition continues to erode through early afternoon. Other clusters of storms will develop and move west to east given marginal deep-layer mean westerly flow. Although small hail 0.50-1.00 inch in diameter is possible with the strongest cores, the primary hazard with the stronger storms will be damaging gusts (50-65 mph) with the more intense water-loaded downdrafts. This activity will likely diminish by the early to mid evening. ...South Dakota/Nebraska into Minnesota/Iowa... Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. An initially appreciable capping inversion will inhibit surface-based storm development until heating gradually weakens inhibition by late afternoon. A very unstable airmass is forecast by late afternoon/early evening, but nebulous forcing lends uncertainty in terms of storm development/timing. Models suggest storms will primarily develop this evening associated with strengthening low-level theta-e advection. Supercells are possible early in the convective life cycle with a risk for all hazards, including the possibility for a couple of tornadoes, but large hail may be the main hazard. Upscale growth into a cluster or MCS is possible near the terminus of a southwesterly 850-mb LLJ with severe gusts the becoming the primary threat. Models vary considerably whether storm intensity is maintained through much of the overnight and beyond the Day-1 period, or if a gradual diminishing in severe occurs. ...Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. Steep low/mid-level lapse rates and a deep, very well-mixed boundary layer should support isolated severe gusts with the stronger thunderstorms. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ..Smith/Weinman.. 07/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0743 AM CDT Fri Jul 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF VIRGINIA/NORTH CAROLINA...AND PARTS OF CENTRAL/EASTERN NEBRASKA...SOUTHEAST SOUTH DAKOTA...SOUTHWEST MINNESOTA...AND WESTERN/CENTRAL IOWA... ...SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a few tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ...Virginia/North Carolina to the Mid-South... A generally west-east oriented quasi-stationary front reinforced by outflow from earlier convection should serve as a low-level forcing mechanism for thunderstorm development this afternoon from parts of VA/NC westward to the Mid-South and vicinity. A seasonably moist airmass will be present today along/south of this front, with surface dewpoints generally ranging from the upper 60s in higher elevations to mid 70s elsewhere. Even though mid-level lapse rates are expected to remain rather modest, ample daytime heating of the moist low-level airmass will contribute to sizable MLCAPE by early to mid afternoon. With a subtropical anticyclone centered off the Southeast Atlantic Coast and stronger flow aloft associated with various mid-level perturbations expected to remain over the Great Lakes/Northeast, large-scale ascent in the vicinity of the surface front will be nebulous at best. Regardless, scattered to numerous thunderstorms should develop along/near this boundary through the afternoon, while spreading generally eastward this evening. With modest mid-level westerly flow forecast, deep-layer shear appears marginal for thunderstorm organization. The greatest threat for scattered damaging winds should focus across parts of VA/NC this afternoon and early evening, where semi-organized clusters and short line segments appear possible given slightly stronger deep-layer shear. Otherwise, isolated damaging winds may occur even with less organized convection farther west towards parts of the TN Valley/Mid-South, as steepened low-level lapse rates potentially support microbursts. There does appear to be a gap in scattered convective coverage across parts of MO and vicinity, where the Marginal Risk has been removed with this update. ...South Dakota/Nebraska into Minnesota/Iowa... Elevated convection across parts of SD may continue to pose an isolated hail threat this morning, before it eventually weakens with the gradual lessening of a southerly low-level jet. A belt of strong westerly mid-level flow will remain in place over the northern tier of the CONUS from MT eastward towards the Great Lakes. Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. Diurnal heating and modestly steepened mid-level lapse rates will contribute to moderate to strong MLCAPE across parts of NE/southeast SD into IA. But, nebulous forcing for ascent and residual capping should tend to suppress surface-based convective development across these areas for much of the day. Occasional severe hail may occur with mainly elevated convection to the north of the front in MN. A gradually strengthening southerly low-level jet this evening (mainly after 00Z) should aid in convective initiation along/near the front from central/northeast NE into southeast SD/southwest MN. Various NAM/RAP forecast soundings across this region suggest ample instability and strong deep-layer shear will be present to support supercells with attendant large hail threat initially. Low-level shear should also be strong enough for a tornado threat with these supercells, although there may be a fairly narrow spatial/temporal window for convection to remain discrete this evening. Upscale growth into a bowing cluster should occur through mid to late evening, with a threat for mainly scattered severe/damaging winds as this convection tracks into parts of IA overnight, before eventually weakening early Saturday morning. ...Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. While low-level moisture and deep-layer shear will remain limited, steepened low/mid-level lapse rates amid a very well-mixed boundary layer should support isolated severe gusts with any thunderstorms that can be sustained amid weak instability. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ..Gleason/Bentley.. 07/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0743 AM CDT Fri Jul 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF VIRGINIA/NORTH CAROLINA...AND PARTS OF CENTRAL/EASTERN NEBRASKA...SOUTHEAST SOUTH DAKOTA...SOUTHWEST MINNESOTA...AND WESTERN/CENTRAL IOWA... ...SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a few tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ...Virginia/North Carolina to the Mid-South... A generally west-east oriented quasi-stationary front reinforced by outflow from earlier convection should serve as a low-level forcing mechanism for thunderstorm development this afternoon from parts of VA/NC westward to the Mid-South and vicinity. A seasonably moist airmass will be present today along/south of this front, with surface dewpoints generally ranging from the upper 60s in higher elevations to mid 70s elsewhere. Even though mid-level lapse rates are expected to remain rather modest, ample daytime heating of the moist low-level airmass will contribute to sizable MLCAPE by early to mid afternoon. With a subtropical anticyclone centered off the Southeast Atlantic Coast and stronger flow aloft associated with various mid-level perturbations expected to remain over the Great Lakes/Northeast, large-scale ascent in the vicinity of the surface front will be nebulous at best. Regardless, scattered to numerous thunderstorms should develop along/near this boundary through the afternoon, while spreading generally eastward this evening. With modest mid-level westerly flow forecast, deep-layer shear appears marginal for thunderstorm organization. The greatest threat for scattered damaging winds should focus across parts of VA/NC this afternoon and early evening, where semi-organized clusters and short line segments appear possible given slightly stronger deep-layer shear. Otherwise, isolated damaging winds may occur even with less organized convection farther west towards parts of the TN Valley/Mid-South, as steepened low-level lapse rates potentially support microbursts. There does appear to be a gap in scattered convective coverage across parts of MO and vicinity, where the Marginal Risk has been removed with this update. ...South Dakota/Nebraska into Minnesota/Iowa... Elevated convection across parts of SD may continue to pose an isolated hail threat this morning, before it eventually weakens with the gradual lessening of a southerly low-level jet. A belt of strong westerly mid-level flow will remain in place over the northern tier of the CONUS from MT eastward towards the Great Lakes. Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. Diurnal heating and modestly steepened mid-level lapse rates will contribute to moderate to strong MLCAPE across parts of NE/southeast SD into IA. But, nebulous forcing for ascent and residual capping should tend to suppress surface-based convective development across these areas for much of the day. Occasional severe hail may occur with mainly elevated convection to the north of the front in MN. A gradually strengthening southerly low-level jet this evening (mainly after 00Z) should aid in convective initiation along/near the front from central/northeast NE into southeast SD/southwest MN. Various NAM/RAP forecast soundings across this region suggest ample instability and strong deep-layer shear will be present to support supercells with attendant large hail threat initially. Low-level shear should also be strong enough for a tornado threat with these supercells, although there may be a fairly narrow spatial/temporal window for convection to remain discrete this evening. Upscale growth into a bowing cluster should occur through mid to late evening, with a threat for mainly scattered severe/damaging winds as this convection tracks into parts of IA overnight, before eventually weakening early Saturday morning. ...Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. While low-level moisture and deep-layer shear will remain limited, steepened low/mid-level lapse rates amid a very well-mixed boundary layer should support isolated severe gusts with any thunderstorms that can be sustained amid weak instability. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ..Gleason/Bentley.. 07/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0743 AM CDT Fri Jul 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF VIRGINIA/NORTH CAROLINA...AND PARTS OF CENTRAL/EASTERN NEBRASKA...SOUTHEAST SOUTH DAKOTA...SOUTHWEST MINNESOTA...AND WESTERN/CENTRAL IOWA... ...SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a few tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ...Virginia/North Carolina to the Mid-South... A generally west-east oriented quasi-stationary front reinforced by outflow from earlier convection should serve as a low-level forcing mechanism for thunderstorm development this afternoon from parts of VA/NC westward to the Mid-South and vicinity. A seasonably moist airmass will be present today along/south of this front, with surface dewpoints generally ranging from the upper 60s in higher elevations to mid 70s elsewhere. Even though mid-level lapse rates are expected to remain rather modest, ample daytime heating of the moist low-level airmass will contribute to sizable MLCAPE by early to mid afternoon. With a subtropical anticyclone centered off the Southeast Atlantic Coast and stronger flow aloft associated with various mid-level perturbations expected to remain over the Great Lakes/Northeast, large-scale ascent in the vicinity of the surface front will be nebulous at best. Regardless, scattered to numerous thunderstorms should develop along/near this boundary through the afternoon, while spreading generally eastward this evening. With modest mid-level westerly flow forecast, deep-layer shear appears marginal for thunderstorm organization. The greatest threat for scattered damaging winds should focus across parts of VA/NC this afternoon and early evening, where semi-organized clusters and short line segments appear possible given slightly stronger deep-layer shear. Otherwise, isolated damaging winds may occur even with less organized convection farther west towards parts of the TN Valley/Mid-South, as steepened low-level lapse rates potentially support microbursts. There does appear to be a gap in scattered convective coverage across parts of MO and vicinity, where the Marginal Risk has been removed with this update. ...South Dakota/Nebraska into Minnesota/Iowa... Elevated convection across parts of SD may continue to pose an isolated hail threat this morning, before it eventually weakens with the gradual lessening of a southerly low-level jet. A belt of strong westerly mid-level flow will remain in place over the northern tier of the CONUS from MT eastward towards the Great Lakes. Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. Diurnal heating and modestly steepened mid-level lapse rates will contribute to moderate to strong MLCAPE across parts of NE/southeast SD into IA. But, nebulous forcing for ascent and residual capping should tend to suppress surface-based convective development across these areas for much of the day. Occasional severe hail may occur with mainly elevated convection to the north of the front in MN. A gradually strengthening southerly low-level jet this evening (mainly after 00Z) should aid in convective initiation along/near the front from central/northeast NE into southeast SD/southwest MN. Various NAM/RAP forecast soundings across this region suggest ample instability and strong deep-layer shear will be present to support supercells with attendant large hail threat initially. Low-level shear should also be strong enough for a tornado threat with these supercells, although there may be a fairly narrow spatial/temporal window for convection to remain discrete this evening. Upscale growth into a bowing cluster should occur through mid to late evening, with a threat for mainly scattered severe/damaging winds as this convection tracks into parts of IA overnight, before eventually weakening early Saturday morning. ...Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. While low-level moisture and deep-layer shear will remain limited, steepened low/mid-level lapse rates amid a very well-mixed boundary layer should support isolated severe gusts with any thunderstorms that can be sustained amid weak instability. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ..Gleason/Bentley.. 07/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0743 AM CDT Fri Jul 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF VIRGINIA/NORTH CAROLINA...AND PARTS OF CENTRAL/EASTERN NEBRASKA...SOUTHEAST SOUTH DAKOTA...SOUTHWEST MINNESOTA...AND WESTERN/CENTRAL IOWA... ...SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a few tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ...Virginia/North Carolina to the Mid-South... A generally west-east oriented quasi-stationary front reinforced by outflow from earlier convection should serve as a low-level forcing mechanism for thunderstorm development this afternoon from parts of VA/NC westward to the Mid-South and vicinity. A seasonably moist airmass will be present today along/south of this front, with surface dewpoints generally ranging from the upper 60s in higher elevations to mid 70s elsewhere. Even though mid-level lapse rates are expected to remain rather modest, ample daytime heating of the moist low-level airmass will contribute to sizable MLCAPE by early to mid afternoon. With a subtropical anticyclone centered off the Southeast Atlantic Coast and stronger flow aloft associated with various mid-level perturbations expected to remain over the Great Lakes/Northeast, large-scale ascent in the vicinity of the surface front will be nebulous at best. Regardless, scattered to numerous thunderstorms should develop along/near this boundary through the afternoon, while spreading generally eastward this evening. With modest mid-level westerly flow forecast, deep-layer shear appears marginal for thunderstorm organization. The greatest threat for scattered damaging winds should focus across parts of VA/NC this afternoon and early evening, where semi-organized clusters and short line segments appear possible given slightly stronger deep-layer shear. Otherwise, isolated damaging winds may occur even with less organized convection farther west towards parts of the TN Valley/Mid-South, as steepened low-level lapse rates potentially support microbursts. There does appear to be a gap in scattered convective coverage across parts of MO and vicinity, where the Marginal Risk has been removed with this update. ...South Dakota/Nebraska into Minnesota/Iowa... Elevated convection across parts of SD may continue to pose an isolated hail threat this morning, before it eventually weakens with the gradual lessening of a southerly low-level jet. A belt of strong westerly mid-level flow will remain in place over the northern tier of the CONUS from MT eastward towards the Great Lakes. Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. Diurnal heating and modestly steepened mid-level lapse rates will contribute to moderate to strong MLCAPE across parts of NE/southeast SD into IA. But, nebulous forcing for ascent and residual capping should tend to suppress surface-based convective development across these areas for much of the day. Occasional severe hail may occur with mainly elevated convection to the north of the front in MN. A gradually strengthening southerly low-level jet this evening (mainly after 00Z) should aid in convective initiation along/near the front from central/northeast NE into southeast SD/southwest MN. Various NAM/RAP forecast soundings across this region suggest ample instability and strong deep-layer shear will be present to support supercells with attendant large hail threat initially. Low-level shear should also be strong enough for a tornado threat with these supercells, although there may be a fairly narrow spatial/temporal window for convection to remain discrete this evening. Upscale growth into a bowing cluster should occur through mid to late evening, with a threat for mainly scattered severe/damaging winds as this convection tracks into parts of IA overnight, before eventually weakening early Saturday morning. ...Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. While low-level moisture and deep-layer shear will remain limited, steepened low/mid-level lapse rates amid a very well-mixed boundary layer should support isolated severe gusts with any thunderstorms that can be sustained amid weak instability. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ..Gleason/Bentley.. 07/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0743 AM CDT Fri Jul 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF VIRGINIA/NORTH CAROLINA...AND PARTS OF CENTRAL/EASTERN NEBRASKA...SOUTHEAST SOUTH DAKOTA...SOUTHWEST MINNESOTA...AND WESTERN/CENTRAL IOWA... ...SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a few tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ...Virginia/North Carolina to the Mid-South... A generally west-east oriented quasi-stationary front reinforced by outflow from earlier convection should serve as a low-level forcing mechanism for thunderstorm development this afternoon from parts of VA/NC westward to the Mid-South and vicinity. A seasonably moist airmass will be present today along/south of this front, with surface dewpoints generally ranging from the upper 60s in higher elevations to mid 70s elsewhere. Even though mid-level lapse rates are expected to remain rather modest, ample daytime heating of the moist low-level airmass will contribute to sizable MLCAPE by early to mid afternoon. With a subtropical anticyclone centered off the Southeast Atlantic Coast and stronger flow aloft associated with various mid-level perturbations expected to remain over the Great Lakes/Northeast, large-scale ascent in the vicinity of the surface front will be nebulous at best. Regardless, scattered to numerous thunderstorms should develop along/near this boundary through the afternoon, while spreading generally eastward this evening. With modest mid-level westerly flow forecast, deep-layer shear appears marginal for thunderstorm organization. The greatest threat for scattered damaging winds should focus across parts of VA/NC this afternoon and early evening, where semi-organized clusters and short line segments appear possible given slightly stronger deep-layer shear. Otherwise, isolated damaging winds may occur even with less organized convection farther west towards parts of the TN Valley/Mid-South, as steepened low-level lapse rates potentially support microbursts. There does appear to be a gap in scattered convective coverage across parts of MO and vicinity, where the Marginal Risk has been removed with this update. ...South Dakota/Nebraska into Minnesota/Iowa... Elevated convection across parts of SD may continue to pose an isolated hail threat this morning, before it eventually weakens with the gradual lessening of a southerly low-level jet. A belt of strong westerly mid-level flow will remain in place over the northern tier of the CONUS from MT eastward towards the Great Lakes. Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. Diurnal heating and modestly steepened mid-level lapse rates will contribute to moderate to strong MLCAPE across parts of NE/southeast SD into IA. But, nebulous forcing for ascent and residual capping should tend to suppress surface-based convective development across these areas for much of the day. Occasional severe hail may occur with mainly elevated convection to the north of the front in MN. A gradually strengthening southerly low-level jet this evening (mainly after 00Z) should aid in convective initiation along/near the front from central/northeast NE into southeast SD/southwest MN. Various NAM/RAP forecast soundings across this region suggest ample instability and strong deep-layer shear will be present to support supercells with attendant large hail threat initially. Low-level shear should also be strong enough for a tornado threat with these supercells, although there may be a fairly narrow spatial/temporal window for convection to remain discrete this evening. Upscale growth into a bowing cluster should occur through mid to late evening, with a threat for mainly scattered severe/damaging winds as this convection tracks into parts of IA overnight, before eventually weakening early Saturday morning. ...Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. While low-level moisture and deep-layer shear will remain limited, steepened low/mid-level lapse rates amid a very well-mixed boundary layer should support isolated severe gusts with any thunderstorms that can be sustained amid weak instability. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ..Gleason/Bentley.. 07/18/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0743 AM CDT Fri Jul 18 2025 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF VIRGINIA/NORTH CAROLINA...AND PARTS OF CENTRAL/EASTERN NEBRASKA...SOUTHEAST SOUTH DAKOTA...SOUTHWEST MINNESOTA...AND WESTERN/CENTRAL IOWA... ...SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a few tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ...Virginia/North Carolina to the Mid-South... A generally west-east oriented quasi-stationary front reinforced by outflow from earlier convection should serve as a low-level forcing mechanism for thunderstorm development this afternoon from parts of VA/NC westward to the Mid-South and vicinity. A seasonably moist airmass will be present today along/south of this front, with surface dewpoints generally ranging from the upper 60s in higher elevations to mid 70s elsewhere. Even though mid-level lapse rates are expected to remain rather modest, ample daytime heating of the moist low-level airmass will contribute to sizable MLCAPE by early to mid afternoon. With a subtropical anticyclone centered off the Southeast Atlantic Coast and stronger flow aloft associated with various mid-level perturbations expected to remain over the Great Lakes/Northeast, large-scale ascent in the vicinity of the surface front will be nebulous at best. Regardless, scattered to numerous thunderstorms should develop along/near this boundary through the afternoon, while spreading generally eastward this evening. With modest mid-level westerly flow forecast, deep-layer shear appears marginal for thunderstorm organization. The greatest threat for scattered damaging winds should focus across parts of VA/NC this afternoon and early evening, where semi-organized clusters and short line segments appear possible given slightly stronger deep-layer shear. Otherwise, isolated damaging winds may occur even with less organized convection farther west towards parts of the TN Valley/Mid-South, as steepened low-level lapse rates potentially support microbursts. There does appear to be a gap in scattered convective coverage across parts of MO and vicinity, where the Marginal Risk has been removed with this update. ...South Dakota/Nebraska into Minnesota/Iowa... Elevated convection across parts of SD may continue to pose an isolated hail threat this morning, before it eventually weakens with the gradual lessening of a southerly low-level jet. A belt of strong westerly mid-level flow will remain in place over the northern tier of the CONUS from MT eastward towards the Great Lakes. Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. Diurnal heating and modestly steepened mid-level lapse rates will contribute to moderate to strong MLCAPE across parts of NE/southeast SD into IA. But, nebulous forcing for ascent and residual capping should tend to suppress surface-based convective development across these areas for much of the day. Occasional severe hail may occur with mainly elevated convection to the north of the front in MN. A gradually strengthening southerly low-level jet this evening (mainly after 00Z) should aid in convective initiation along/near the front from central/northeast NE into southeast SD/southwest MN. Various NAM/RAP forecast soundings across this region suggest ample instability and strong deep-layer shear will be present to support supercells with attendant large hail threat initially. Low-level shear should also be strong enough for a tornado threat with these supercells, although there may be a fairly narrow spatial/temporal window for convection to remain discrete this evening. Upscale growth into a bowing cluster should occur through mid to late evening, with a threat for mainly scattered severe/damaging winds as this convection tracks into parts of IA overnight, before eventually weakening early Saturday morning. ...Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. While low-level moisture and deep-layer shear will remain limited, steepened low/mid-level lapse rates amid a very well-mixed boundary layer should support isolated severe gusts with any thunderstorms that can be sustained amid weak instability. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ..Gleason/Bentley.. 07/18/2025 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0354 AM CDT Fri Jul 18 2025 Valid 211200Z - 261200Z ...DISCUSSION... Medium-range guidance suggests that mid/upper ridging may remain a prominent influence across much of the central and southeastern U.S. through this period. Beneath its northern periphery, across parts of the northern Great Plains into Upper Midwest and Great Lakes/Ohio Valley, it appears that a seasonably moist boundary-layer may become characterized by moderate to strong diurnal destabilization each day. However, forcing for ascent to support convective development remains unclear, and might be largely dependent on sub-synoptic features with low predictability, particularly at this extended range. Sizable spread exists among the output concerning synoptic features within the westerlies, as well. However, there appears some signal that a short wave perturbation, emerging either from the Pacific Northwest or northwestern Canadian provinces early next week, could be accompanied by an eastward advecting plume of elevated mixed-layer air, low-level moistening and strengthening lower/mid-tropospheric wind fields across parts of the Upper Midwest/Great Lakes toward the St. Lawrence Valley/Northeast late next Wednesday into Friday. It might not be out of the question that this regime could become supportive of one or two sustained, organized clusters of storms capable of producing swaths of damaging winds and some hail. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0354 AM CDT Fri Jul 18 2025 Valid 211200Z - 261200Z ...DISCUSSION... Medium-range guidance suggests that mid/upper ridging may remain a prominent influence across much of the central and southeastern U.S. through this period. Beneath its northern periphery, across parts of the northern Great Plains into Upper Midwest and Great Lakes/Ohio Valley, it appears that a seasonably moist boundary-layer may become characterized by moderate to strong diurnal destabilization each day. However, forcing for ascent to support convective development remains unclear, and might be largely dependent on sub-synoptic features with low predictability, particularly at this extended range. Sizable spread exists among the output concerning synoptic features within the westerlies, as well. However, there appears some signal that a short wave perturbation, emerging either from the Pacific Northwest or northwestern Canadian provinces early next week, could be accompanied by an eastward advecting plume of elevated mixed-layer air, low-level moistening and strengthening lower/mid-tropospheric wind fields across parts of the Upper Midwest/Great Lakes toward the St. Lawrence Valley/Northeast late next Wednesday into Friday. It might not be out of the question that this regime could become supportive of one or two sustained, organized clusters of storms capable of producing swaths of damaging winds and some hail. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0354 AM CDT Fri Jul 18 2025 Valid 211200Z - 261200Z ...DISCUSSION... Medium-range guidance suggests that mid/upper ridging may remain a prominent influence across much of the central and southeastern U.S. through this period. Beneath its northern periphery, across parts of the northern Great Plains into Upper Midwest and Great Lakes/Ohio Valley, it appears that a seasonably moist boundary-layer may become characterized by moderate to strong diurnal destabilization each day. However, forcing for ascent to support convective development remains unclear, and might be largely dependent on sub-synoptic features with low predictability, particularly at this extended range. Sizable spread exists among the output concerning synoptic features within the westerlies, as well. However, there appears some signal that a short wave perturbation, emerging either from the Pacific Northwest or northwestern Canadian provinces early next week, could be accompanied by an eastward advecting plume of elevated mixed-layer air, low-level moistening and strengthening lower/mid-tropospheric wind fields across parts of the Upper Midwest/Great Lakes toward the St. Lawrence Valley/Northeast late next Wednesday into Friday. It might not be out of the question that this regime could become supportive of one or two sustained, organized clusters of storms capable of producing swaths of damaging winds and some hail. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0354 AM CDT Fri Jul 18 2025 Valid 211200Z - 261200Z ...DISCUSSION... Medium-range guidance suggests that mid/upper ridging may remain a prominent influence across much of the central and southeastern U.S. through this period. Beneath its northern periphery, across parts of the northern Great Plains into Upper Midwest and Great Lakes/Ohio Valley, it appears that a seasonably moist boundary-layer may become characterized by moderate to strong diurnal destabilization each day. However, forcing for ascent to support convective development remains unclear, and might be largely dependent on sub-synoptic features with low predictability, particularly at this extended range. Sizable spread exists among the output concerning synoptic features within the westerlies, as well. However, there appears some signal that a short wave perturbation, emerging either from the Pacific Northwest or northwestern Canadian provinces early next week, could be accompanied by an eastward advecting plume of elevated mixed-layer air, low-level moistening and strengthening lower/mid-tropospheric wind fields across parts of the Upper Midwest/Great Lakes toward the St. Lawrence Valley/Northeast late next Wednesday into Friday. It might not be out of the question that this regime could become supportive of one or two sustained, organized clusters of storms capable of producing swaths of damaging winds and some hail. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0354 AM CDT Fri Jul 18 2025 Valid 211200Z - 261200Z ...DISCUSSION... Medium-range guidance suggests that mid/upper ridging may remain a prominent influence across much of the central and southeastern U.S. through this period. Beneath its northern periphery, across parts of the northern Great Plains into Upper Midwest and Great Lakes/Ohio Valley, it appears that a seasonably moist boundary-layer may become characterized by moderate to strong diurnal destabilization each day. However, forcing for ascent to support convective development remains unclear, and might be largely dependent on sub-synoptic features with low predictability, particularly at this extended range. Sizable spread exists among the output concerning synoptic features within the westerlies, as well. However, there appears some signal that a short wave perturbation, emerging either from the Pacific Northwest or northwestern Canadian provinces early next week, could be accompanied by an eastward advecting plume of elevated mixed-layer air, low-level moistening and strengthening lower/mid-tropospheric wind fields across parts of the Upper Midwest/Great Lakes toward the St. Lawrence Valley/Northeast late next Wednesday into Friday. It might not be out of the question that this regime could become supportive of one or two sustained, organized clusters of storms capable of producing swaths of damaging winds and some hail. Read more