Severe Storms

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0341 PM CDT Fri Jul 18 2025 Valid 201200Z - 261200Z A mid/upper-level tough is forecast to deepen across the Pacific Northwest Day 3/Sunday into Day 4/Monday. Thereafter, the evolution of the trough is somewhat uncertain, largely due to inter/intra-model variability. Though, many recent solutions now suggest some form of splitting with a portion of the trough ejecting across the northern Rockies and another becoming cutoff (or redeveloping) off/near the coast of California/Oregon through the remainder of the week. ...Day 3/Sunday - Day 5/Tuesday: Wind/RH... Increasing mid-level winds - associated with the aforementioned trough - will promote a broadening area of dry/breezy southwesterly flow Day 3/Sunday across portions of the northern Great Basin, far northeastern California, southeastern Oregon, and southwest Montana. At this time, locally critical conditions appear most likely across wind-prone areas of the Snake River Plain in Idaho. Fire weather conditions are forecast to shift a bit southward while also increasing in coverage and intensity Day 4/Monday, as the aforementioned trough continues to deepen. While an area of critical fire weather conditions appears probable, relatively poor run-to-run model consistency precludes increasing critical probabilities to 70% at this time. Dry/breezy conditions are forecast to linger into Day 5/Tuesday across the Great Basin. Though, relaxing mid-level winds and reduced surface pressure gradients should promote lighter surface winds and locally elevated fire weather conditions. ...Day 4/Monday - Day 5/Tuesday: Dry Thunderstorms... Isolated dry thunderstorms are possible Day 4/Monday into Day 5/Tuesday across portions of northern Great Basin, Northwest, and northern Rockies, as increasing moisture associated with the aforementioned trough impinges on the area. While forecast guidance suggests precipitable water values may be relatively high (0.8 - 1+ inch), somewhat fast-moving storm motions and critically receptive fuels suggest a mix of wet/dry modes. At this time, uncertainty remains too large to introduce probabilities for dry thunderstorms. ..Elliott.. 07/18/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0341 PM CDT Fri Jul 18 2025 Valid 201200Z - 261200Z A mid/upper-level tough is forecast to deepen across the Pacific Northwest Day 3/Sunday into Day 4/Monday. Thereafter, the evolution of the trough is somewhat uncertain, largely due to inter/intra-model variability. Though, many recent solutions now suggest some form of splitting with a portion of the trough ejecting across the northern Rockies and another becoming cutoff (or redeveloping) off/near the coast of California/Oregon through the remainder of the week. ...Day 3/Sunday - Day 5/Tuesday: Wind/RH... Increasing mid-level winds - associated with the aforementioned trough - will promote a broadening area of dry/breezy southwesterly flow Day 3/Sunday across portions of the northern Great Basin, far northeastern California, southeastern Oregon, and southwest Montana. At this time, locally critical conditions appear most likely across wind-prone areas of the Snake River Plain in Idaho. Fire weather conditions are forecast to shift a bit southward while also increasing in coverage and intensity Day 4/Monday, as the aforementioned trough continues to deepen. While an area of critical fire weather conditions appears probable, relatively poor run-to-run model consistency precludes increasing critical probabilities to 70% at this time. Dry/breezy conditions are forecast to linger into Day 5/Tuesday across the Great Basin. Though, relaxing mid-level winds and reduced surface pressure gradients should promote lighter surface winds and locally elevated fire weather conditions. ...Day 4/Monday - Day 5/Tuesday: Dry Thunderstorms... Isolated dry thunderstorms are possible Day 4/Monday into Day 5/Tuesday across portions of northern Great Basin, Northwest, and northern Rockies, as increasing moisture associated with the aforementioned trough impinges on the area. While forecast guidance suggests precipitable water values may be relatively high (0.8 - 1+ inch), somewhat fast-moving storm motions and critically receptive fuels suggest a mix of wet/dry modes. At this time, uncertainty remains too large to introduce probabilities for dry thunderstorms. ..Elliott.. 07/18/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0341 PM CDT Fri Jul 18 2025 Valid 201200Z - 261200Z A mid/upper-level tough is forecast to deepen across the Pacific Northwest Day 3/Sunday into Day 4/Monday. Thereafter, the evolution of the trough is somewhat uncertain, largely due to inter/intra-model variability. Though, many recent solutions now suggest some form of splitting with a portion of the trough ejecting across the northern Rockies and another becoming cutoff (or redeveloping) off/near the coast of California/Oregon through the remainder of the week. ...Day 3/Sunday - Day 5/Tuesday: Wind/RH... Increasing mid-level winds - associated with the aforementioned trough - will promote a broadening area of dry/breezy southwesterly flow Day 3/Sunday across portions of the northern Great Basin, far northeastern California, southeastern Oregon, and southwest Montana. At this time, locally critical conditions appear most likely across wind-prone areas of the Snake River Plain in Idaho. Fire weather conditions are forecast to shift a bit southward while also increasing in coverage and intensity Day 4/Monday, as the aforementioned trough continues to deepen. While an area of critical fire weather conditions appears probable, relatively poor run-to-run model consistency precludes increasing critical probabilities to 70% at this time. Dry/breezy conditions are forecast to linger into Day 5/Tuesday across the Great Basin. Though, relaxing mid-level winds and reduced surface pressure gradients should promote lighter surface winds and locally elevated fire weather conditions. ...Day 4/Monday - Day 5/Tuesday: Dry Thunderstorms... Isolated dry thunderstorms are possible Day 4/Monday into Day 5/Tuesday across portions of northern Great Basin, Northwest, and northern Rockies, as increasing moisture associated with the aforementioned trough impinges on the area. While forecast guidance suggests precipitable water values may be relatively high (0.8 - 1+ inch), somewhat fast-moving storm motions and critically receptive fuels suggest a mix of wet/dry modes. At this time, uncertainty remains too large to introduce probabilities for dry thunderstorms. ..Elliott.. 07/18/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0341 PM CDT Fri Jul 18 2025 Valid 201200Z - 261200Z A mid/upper-level tough is forecast to deepen across the Pacific Northwest Day 3/Sunday into Day 4/Monday. Thereafter, the evolution of the trough is somewhat uncertain, largely due to inter/intra-model variability. Though, many recent solutions now suggest some form of splitting with a portion of the trough ejecting across the northern Rockies and another becoming cutoff (or redeveloping) off/near the coast of California/Oregon through the remainder of the week. ...Day 3/Sunday - Day 5/Tuesday: Wind/RH... Increasing mid-level winds - associated with the aforementioned trough - will promote a broadening area of dry/breezy southwesterly flow Day 3/Sunday across portions of the northern Great Basin, far northeastern California, southeastern Oregon, and southwest Montana. At this time, locally critical conditions appear most likely across wind-prone areas of the Snake River Plain in Idaho. Fire weather conditions are forecast to shift a bit southward while also increasing in coverage and intensity Day 4/Monday, as the aforementioned trough continues to deepen. While an area of critical fire weather conditions appears probable, relatively poor run-to-run model consistency precludes increasing critical probabilities to 70% at this time. Dry/breezy conditions are forecast to linger into Day 5/Tuesday across the Great Basin. Though, relaxing mid-level winds and reduced surface pressure gradients should promote lighter surface winds and locally elevated fire weather conditions. ...Day 4/Monday - Day 5/Tuesday: Dry Thunderstorms... Isolated dry thunderstorms are possible Day 4/Monday into Day 5/Tuesday across portions of northern Great Basin, Northwest, and northern Rockies, as increasing moisture associated with the aforementioned trough impinges on the area. While forecast guidance suggests precipitable water values may be relatively high (0.8 - 1+ inch), somewhat fast-moving storm motions and critically receptive fuels suggest a mix of wet/dry modes. At this time, uncertainty remains too large to introduce probabilities for dry thunderstorms. ..Elliott.. 07/18/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0341 PM CDT Fri Jul 18 2025 Valid 201200Z - 261200Z A mid/upper-level tough is forecast to deepen across the Pacific Northwest Day 3/Sunday into Day 4/Monday. Thereafter, the evolution of the trough is somewhat uncertain, largely due to inter/intra-model variability. Though, many recent solutions now suggest some form of splitting with a portion of the trough ejecting across the northern Rockies and another becoming cutoff (or redeveloping) off/near the coast of California/Oregon through the remainder of the week. ...Day 3/Sunday - Day 5/Tuesday: Wind/RH... Increasing mid-level winds - associated with the aforementioned trough - will promote a broadening area of dry/breezy southwesterly flow Day 3/Sunday across portions of the northern Great Basin, far northeastern California, southeastern Oregon, and southwest Montana. At this time, locally critical conditions appear most likely across wind-prone areas of the Snake River Plain in Idaho. Fire weather conditions are forecast to shift a bit southward while also increasing in coverage and intensity Day 4/Monday, as the aforementioned trough continues to deepen. While an area of critical fire weather conditions appears probable, relatively poor run-to-run model consistency precludes increasing critical probabilities to 70% at this time. Dry/breezy conditions are forecast to linger into Day 5/Tuesday across the Great Basin. Though, relaxing mid-level winds and reduced surface pressure gradients should promote lighter surface winds and locally elevated fire weather conditions. ...Day 4/Monday - Day 5/Tuesday: Dry Thunderstorms... Isolated dry thunderstorms are possible Day 4/Monday into Day 5/Tuesday across portions of northern Great Basin, Northwest, and northern Rockies, as increasing moisture associated with the aforementioned trough impinges on the area. While forecast guidance suggests precipitable water values may be relatively high (0.8 - 1+ inch), somewhat fast-moving storm motions and critically receptive fuels suggest a mix of wet/dry modes. At this time, uncertainty remains too large to introduce probabilities for dry thunderstorms. ..Elliott.. 07/18/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0341 PM CDT Fri Jul 18 2025 Valid 201200Z - 261200Z A mid/upper-level tough is forecast to deepen across the Pacific Northwest Day 3/Sunday into Day 4/Monday. Thereafter, the evolution of the trough is somewhat uncertain, largely due to inter/intra-model variability. Though, many recent solutions now suggest some form of splitting with a portion of the trough ejecting across the northern Rockies and another becoming cutoff (or redeveloping) off/near the coast of California/Oregon through the remainder of the week. ...Day 3/Sunday - Day 5/Tuesday: Wind/RH... Increasing mid-level winds - associated with the aforementioned trough - will promote a broadening area of dry/breezy southwesterly flow Day 3/Sunday across portions of the northern Great Basin, far northeastern California, southeastern Oregon, and southwest Montana. At this time, locally critical conditions appear most likely across wind-prone areas of the Snake River Plain in Idaho. Fire weather conditions are forecast to shift a bit southward while also increasing in coverage and intensity Day 4/Monday, as the aforementioned trough continues to deepen. While an area of critical fire weather conditions appears probable, relatively poor run-to-run model consistency precludes increasing critical probabilities to 70% at this time. Dry/breezy conditions are forecast to linger into Day 5/Tuesday across the Great Basin. Though, relaxing mid-level winds and reduced surface pressure gradients should promote lighter surface winds and locally elevated fire weather conditions. ...Day 4/Monday - Day 5/Tuesday: Dry Thunderstorms... Isolated dry thunderstorms are possible Day 4/Monday into Day 5/Tuesday across portions of northern Great Basin, Northwest, and northern Rockies, as increasing moisture associated with the aforementioned trough impinges on the area. While forecast guidance suggests precipitable water values may be relatively high (0.8 - 1+ inch), somewhat fast-moving storm motions and critically receptive fuels suggest a mix of wet/dry modes. At this time, uncertainty remains too large to introduce probabilities for dry thunderstorms. ..Elliott.. 07/18/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0341 PM CDT Fri Jul 18 2025 Valid 201200Z - 261200Z A mid/upper-level tough is forecast to deepen across the Pacific Northwest Day 3/Sunday into Day 4/Monday. Thereafter, the evolution of the trough is somewhat uncertain, largely due to inter/intra-model variability. Though, many recent solutions now suggest some form of splitting with a portion of the trough ejecting across the northern Rockies and another becoming cutoff (or redeveloping) off/near the coast of California/Oregon through the remainder of the week. ...Day 3/Sunday - Day 5/Tuesday: Wind/RH... Increasing mid-level winds - associated with the aforementioned trough - will promote a broadening area of dry/breezy southwesterly flow Day 3/Sunday across portions of the northern Great Basin, far northeastern California, southeastern Oregon, and southwest Montana. At this time, locally critical conditions appear most likely across wind-prone areas of the Snake River Plain in Idaho. Fire weather conditions are forecast to shift a bit southward while also increasing in coverage and intensity Day 4/Monday, as the aforementioned trough continues to deepen. While an area of critical fire weather conditions appears probable, relatively poor run-to-run model consistency precludes increasing critical probabilities to 70% at this time. Dry/breezy conditions are forecast to linger into Day 5/Tuesday across the Great Basin. Though, relaxing mid-level winds and reduced surface pressure gradients should promote lighter surface winds and locally elevated fire weather conditions. ...Day 4/Monday - Day 5/Tuesday: Dry Thunderstorms... Isolated dry thunderstorms are possible Day 4/Monday into Day 5/Tuesday across portions of northern Great Basin, Northwest, and northern Rockies, as increasing moisture associated with the aforementioned trough impinges on the area. While forecast guidance suggests precipitable water values may be relatively high (0.8 - 1+ inch), somewhat fast-moving storm motions and critically receptive fuels suggest a mix of wet/dry modes. At this time, uncertainty remains too large to introduce probabilities for dry thunderstorms. ..Elliott.. 07/18/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0341 PM CDT Fri Jul 18 2025 Valid 201200Z - 261200Z A mid/upper-level tough is forecast to deepen across the Pacific Northwest Day 3/Sunday into Day 4/Monday. Thereafter, the evolution of the trough is somewhat uncertain, largely due to inter/intra-model variability. Though, many recent solutions now suggest some form of splitting with a portion of the trough ejecting across the northern Rockies and another becoming cutoff (or redeveloping) off/near the coast of California/Oregon through the remainder of the week. ...Day 3/Sunday - Day 5/Tuesday: Wind/RH... Increasing mid-level winds - associated with the aforementioned trough - will promote a broadening area of dry/breezy southwesterly flow Day 3/Sunday across portions of the northern Great Basin, far northeastern California, southeastern Oregon, and southwest Montana. At this time, locally critical conditions appear most likely across wind-prone areas of the Snake River Plain in Idaho. Fire weather conditions are forecast to shift a bit southward while also increasing in coverage and intensity Day 4/Monday, as the aforementioned trough continues to deepen. While an area of critical fire weather conditions appears probable, relatively poor run-to-run model consistency precludes increasing critical probabilities to 70% at this time. Dry/breezy conditions are forecast to linger into Day 5/Tuesday across the Great Basin. Though, relaxing mid-level winds and reduced surface pressure gradients should promote lighter surface winds and locally elevated fire weather conditions. ...Day 4/Monday - Day 5/Tuesday: Dry Thunderstorms... Isolated dry thunderstorms are possible Day 4/Monday into Day 5/Tuesday across portions of northern Great Basin, Northwest, and northern Rockies, as increasing moisture associated with the aforementioned trough impinges on the area. While forecast guidance suggests precipitable water values may be relatively high (0.8 - 1+ inch), somewhat fast-moving storm motions and critically receptive fuels suggest a mix of wet/dry modes. At this time, uncertainty remains too large to introduce probabilities for dry thunderstorms. ..Elliott.. 07/18/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0341 PM CDT Fri Jul 18 2025 Valid 201200Z - 261200Z A mid/upper-level tough is forecast to deepen across the Pacific Northwest Day 3/Sunday into Day 4/Monday. Thereafter, the evolution of the trough is somewhat uncertain, largely due to inter/intra-model variability. Though, many recent solutions now suggest some form of splitting with a portion of the trough ejecting across the northern Rockies and another becoming cutoff (or redeveloping) off/near the coast of California/Oregon through the remainder of the week. ...Day 3/Sunday - Day 5/Tuesday: Wind/RH... Increasing mid-level winds - associated with the aforementioned trough - will promote a broadening area of dry/breezy southwesterly flow Day 3/Sunday across portions of the northern Great Basin, far northeastern California, southeastern Oregon, and southwest Montana. At this time, locally critical conditions appear most likely across wind-prone areas of the Snake River Plain in Idaho. Fire weather conditions are forecast to shift a bit southward while also increasing in coverage and intensity Day 4/Monday, as the aforementioned trough continues to deepen. While an area of critical fire weather conditions appears probable, relatively poor run-to-run model consistency precludes increasing critical probabilities to 70% at this time. Dry/breezy conditions are forecast to linger into Day 5/Tuesday across the Great Basin. Though, relaxing mid-level winds and reduced surface pressure gradients should promote lighter surface winds and locally elevated fire weather conditions. ...Day 4/Monday - Day 5/Tuesday: Dry Thunderstorms... Isolated dry thunderstorms are possible Day 4/Monday into Day 5/Tuesday across portions of northern Great Basin, Northwest, and northern Rockies, as increasing moisture associated with the aforementioned trough impinges on the area. While forecast guidance suggests precipitable water values may be relatively high (0.8 - 1+ inch), somewhat fast-moving storm motions and critically receptive fuels suggest a mix of wet/dry modes. At this time, uncertainty remains too large to introduce probabilities for dry thunderstorms. ..Elliott.. 07/18/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0341 PM CDT Fri Jul 18 2025 Valid 201200Z - 261200Z A mid/upper-level tough is forecast to deepen across the Pacific Northwest Day 3/Sunday into Day 4/Monday. Thereafter, the evolution of the trough is somewhat uncertain, largely due to inter/intra-model variability. Though, many recent solutions now suggest some form of splitting with a portion of the trough ejecting across the northern Rockies and another becoming cutoff (or redeveloping) off/near the coast of California/Oregon through the remainder of the week. ...Day 3/Sunday - Day 5/Tuesday: Wind/RH... Increasing mid-level winds - associated with the aforementioned trough - will promote a broadening area of dry/breezy southwesterly flow Day 3/Sunday across portions of the northern Great Basin, far northeastern California, southeastern Oregon, and southwest Montana. At this time, locally critical conditions appear most likely across wind-prone areas of the Snake River Plain in Idaho. Fire weather conditions are forecast to shift a bit southward while also increasing in coverage and intensity Day 4/Monday, as the aforementioned trough continues to deepen. While an area of critical fire weather conditions appears probable, relatively poor run-to-run model consistency precludes increasing critical probabilities to 70% at this time. Dry/breezy conditions are forecast to linger into Day 5/Tuesday across the Great Basin. Though, relaxing mid-level winds and reduced surface pressure gradients should promote lighter surface winds and locally elevated fire weather conditions. ...Day 4/Monday - Day 5/Tuesday: Dry Thunderstorms... Isolated dry thunderstorms are possible Day 4/Monday into Day 5/Tuesday across portions of northern Great Basin, Northwest, and northern Rockies, as increasing moisture associated with the aforementioned trough impinges on the area. While forecast guidance suggests precipitable water values may be relatively high (0.8 - 1+ inch), somewhat fast-moving storm motions and critically receptive fuels suggest a mix of wet/dry modes. At this time, uncertainty remains too large to introduce probabilities for dry thunderstorms. ..Elliott.. 07/18/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0341 PM CDT Fri Jul 18 2025 Valid 201200Z - 261200Z A mid/upper-level tough is forecast to deepen across the Pacific Northwest Day 3/Sunday into Day 4/Monday. Thereafter, the evolution of the trough is somewhat uncertain, largely due to inter/intra-model variability. Though, many recent solutions now suggest some form of splitting with a portion of the trough ejecting across the northern Rockies and another becoming cutoff (or redeveloping) off/near the coast of California/Oregon through the remainder of the week. ...Day 3/Sunday - Day 5/Tuesday: Wind/RH... Increasing mid-level winds - associated with the aforementioned trough - will promote a broadening area of dry/breezy southwesterly flow Day 3/Sunday across portions of the northern Great Basin, far northeastern California, southeastern Oregon, and southwest Montana. At this time, locally critical conditions appear most likely across wind-prone areas of the Snake River Plain in Idaho. Fire weather conditions are forecast to shift a bit southward while also increasing in coverage and intensity Day 4/Monday, as the aforementioned trough continues to deepen. While an area of critical fire weather conditions appears probable, relatively poor run-to-run model consistency precludes increasing critical probabilities to 70% at this time. Dry/breezy conditions are forecast to linger into Day 5/Tuesday across the Great Basin. Though, relaxing mid-level winds and reduced surface pressure gradients should promote lighter surface winds and locally elevated fire weather conditions. ...Day 4/Monday - Day 5/Tuesday: Dry Thunderstorms... Isolated dry thunderstorms are possible Day 4/Monday into Day 5/Tuesday across portions of northern Great Basin, Northwest, and northern Rockies, as increasing moisture associated with the aforementioned trough impinges on the area. While forecast guidance suggests precipitable water values may be relatively high (0.8 - 1+ inch), somewhat fast-moving storm motions and critically receptive fuels suggest a mix of wet/dry modes. At this time, uncertainty remains too large to introduce probabilities for dry thunderstorms. ..Elliott.. 07/18/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0341 PM CDT Fri Jul 18 2025 Valid 201200Z - 261200Z A mid/upper-level tough is forecast to deepen across the Pacific Northwest Day 3/Sunday into Day 4/Monday. Thereafter, the evolution of the trough is somewhat uncertain, largely due to inter/intra-model variability. Though, many recent solutions now suggest some form of splitting with a portion of the trough ejecting across the northern Rockies and another becoming cutoff (or redeveloping) off/near the coast of California/Oregon through the remainder of the week. ...Day 3/Sunday - Day 5/Tuesday: Wind/RH... Increasing mid-level winds - associated with the aforementioned trough - will promote a broadening area of dry/breezy southwesterly flow Day 3/Sunday across portions of the northern Great Basin, far northeastern California, southeastern Oregon, and southwest Montana. At this time, locally critical conditions appear most likely across wind-prone areas of the Snake River Plain in Idaho. Fire weather conditions are forecast to shift a bit southward while also increasing in coverage and intensity Day 4/Monday, as the aforementioned trough continues to deepen. While an area of critical fire weather conditions appears probable, relatively poor run-to-run model consistency precludes increasing critical probabilities to 70% at this time. Dry/breezy conditions are forecast to linger into Day 5/Tuesday across the Great Basin. Though, relaxing mid-level winds and reduced surface pressure gradients should promote lighter surface winds and locally elevated fire weather conditions. ...Day 4/Monday - Day 5/Tuesday: Dry Thunderstorms... Isolated dry thunderstorms are possible Day 4/Monday into Day 5/Tuesday across portions of northern Great Basin, Northwest, and northern Rockies, as increasing moisture associated with the aforementioned trough impinges on the area. While forecast guidance suggests precipitable water values may be relatively high (0.8 - 1+ inch), somewhat fast-moving storm motions and critically receptive fuels suggest a mix of wet/dry modes. At this time, uncertainty remains too large to introduce probabilities for dry thunderstorms. ..Elliott.. 07/18/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Fri Jul 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS INTO THE MIDWEST AND PARTS OF THE MID-ATLANTIC... ...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. ...20Z Update... The primary change to the Day 1 20Z Convective Outlook update was to make minor eastward expansions of wind probabilities into eastern IA, as some of the latest convection allowing guidance depicts an MCS persisting into this region. Otherwise, the previous forecast (see below) remains on track, with very small adjustments made to thunder/severe probabilities to account for observational trends and/or guidance consensus updates. ..Squitieri.. 07/18/2025 .PREV DISCUSSION... /ISSUED 1106 AM CDT Fri Jul 18 2025/ ...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. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Fri Jul 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS INTO THE MIDWEST AND PARTS OF THE MID-ATLANTIC... ...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. ...20Z Update... The primary change to the Day 1 20Z Convective Outlook update was to make minor eastward expansions of wind probabilities into eastern IA, as some of the latest convection allowing guidance depicts an MCS persisting into this region. Otherwise, the previous forecast (see below) remains on track, with very small adjustments made to thunder/severe probabilities to account for observational trends and/or guidance consensus updates. ..Squitieri.. 07/18/2025 .PREV DISCUSSION... /ISSUED 1106 AM CDT Fri Jul 18 2025/ ...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. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Fri Jul 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS INTO THE MIDWEST AND PARTS OF THE MID-ATLANTIC... ...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. ...20Z Update... The primary change to the Day 1 20Z Convective Outlook update was to make minor eastward expansions of wind probabilities into eastern IA, as some of the latest convection allowing guidance depicts an MCS persisting into this region. Otherwise, the previous forecast (see below) remains on track, with very small adjustments made to thunder/severe probabilities to account for observational trends and/or guidance consensus updates. ..Squitieri.. 07/18/2025 .PREV DISCUSSION... /ISSUED 1106 AM CDT Fri Jul 18 2025/ ...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. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Fri Jul 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS INTO THE MIDWEST AND PARTS OF THE MID-ATLANTIC... ...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. ...20Z Update... The primary change to the Day 1 20Z Convective Outlook update was to make minor eastward expansions of wind probabilities into eastern IA, as some of the latest convection allowing guidance depicts an MCS persisting into this region. Otherwise, the previous forecast (see below) remains on track, with very small adjustments made to thunder/severe probabilities to account for observational trends and/or guidance consensus updates. ..Squitieri.. 07/18/2025 .PREV DISCUSSION... /ISSUED 1106 AM CDT Fri Jul 18 2025/ ...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. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Fri Jul 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS INTO THE MIDWEST AND PARTS OF THE MID-ATLANTIC... ...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. ...20Z Update... The primary change to the Day 1 20Z Convective Outlook update was to make minor eastward expansions of wind probabilities into eastern IA, as some of the latest convection allowing guidance depicts an MCS persisting into this region. Otherwise, the previous forecast (see below) remains on track, with very small adjustments made to thunder/severe probabilities to account for observational trends and/or guidance consensus updates. ..Squitieri.. 07/18/2025 .PREV DISCUSSION... /ISSUED 1106 AM CDT Fri Jul 18 2025/ ...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. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Fri Jul 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS INTO THE MIDWEST AND PARTS OF THE MID-ATLANTIC... ...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. ...20Z Update... The primary change to the Day 1 20Z Convective Outlook update was to make minor eastward expansions of wind probabilities into eastern IA, as some of the latest convection allowing guidance depicts an MCS persisting into this region. Otherwise, the previous forecast (see below) remains on track, with very small adjustments made to thunder/severe probabilities to account for observational trends and/or guidance consensus updates. ..Squitieri.. 07/18/2025 .PREV DISCUSSION... /ISSUED 1106 AM CDT Fri Jul 18 2025/ ...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. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Fri Jul 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS INTO THE MIDWEST AND PARTS OF THE MID-ATLANTIC... ...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. ...20Z Update... The primary change to the Day 1 20Z Convective Outlook update was to make minor eastward expansions of wind probabilities into eastern IA, as some of the latest convection allowing guidance depicts an MCS persisting into this region. Otherwise, the previous forecast (see below) remains on track, with very small adjustments made to thunder/severe probabilities to account for observational trends and/or guidance consensus updates. ..Squitieri.. 07/18/2025 .PREV DISCUSSION... /ISSUED 1106 AM CDT Fri Jul 18 2025/ ...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. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Fri Jul 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS INTO THE MIDWEST AND PARTS OF THE MID-ATLANTIC... ...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. ...20Z Update... The primary change to the Day 1 20Z Convective Outlook update was to make minor eastward expansions of wind probabilities into eastern IA, as some of the latest convection allowing guidance depicts an MCS persisting into this region. Otherwise, the previous forecast (see below) remains on track, with very small adjustments made to thunder/severe probabilities to account for observational trends and/or guidance consensus updates. ..Squitieri.. 07/18/2025 .PREV DISCUSSION... /ISSUED 1106 AM CDT Fri Jul 18 2025/ ...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. Read more