Severe Storms

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0730 AM CDT Wed Aug 20 2025 Valid 201300Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF TEXAS/DEEP SOUTH AND NORTHERN PLAINS... ...SUMMARY... Scattered thunderstorms from Texas across the Lower Mississippi Valley and Gulf Coast states may pose a risk for localized damaging wind gusts this afternoon and evening. Isolated severe thunderstorms may also occur across eastern Montana and northern North Dakota. ...Texas to Lower Mississippi Valley/Gulf Coast States... A convectively augmented effective front will continue to progress southward, southward-shifting the potential for microburst-related wind damage regionally. Diurnal heating of a moist boundary layer will result in a moderately to strongly unstable and weakly capped airmass by afternoon, with the strongest buoyancy (2500+ J/kg MLCAPE) expected across central/east Texas east-northeastward to Mississippi/western Alabama/southern Tennessee. Some small-scale clusters may evolve, but weak vertical shear will otherwise tend to keep the overall pulse-type damaging wind potential very isolated. ...Northern Plains... The region will be influenced by late-day/nighttime height falls as a shortwave trough emerges eastward from the Canadian Rockies, with an eastward-advancing cold front moving across eastern Montana into North Dakota tonight. A narrow corridor of moderate to large buoyancy is expected along/ahead of the surface cold front, and near a pre-frontal surface trough. Beneath a plume of warm elevated mixed-layer air, mid/upper-level support for the initiation of boundary-layer based thunderstorm development is forecast to generally remain north of the international border. One exception may be in the post-frontal environment across eastern Montana, the environment would be conducive to a few severe storms capable of hail/wind. While the risk for severe thunderstorms appears largely conditional into North Dakota where stronger destabilization is expected, isolated deeper convective development is plausible across northwestern North Dakota in proximity to the surface low/front late this afternoon, and more so this evening. Should this occur, forecast soundings indicate the environment would support isolated supercell development and related severe-weather risks. ..Guyer/Marsh.. 08/20/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0730 AM CDT Wed Aug 20 2025 Valid 201300Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF TEXAS/DEEP SOUTH AND NORTHERN PLAINS... ...SUMMARY... Scattered thunderstorms from Texas across the Lower Mississippi Valley and Gulf Coast states may pose a risk for localized damaging wind gusts this afternoon and evening. Isolated severe thunderstorms may also occur across eastern Montana and northern North Dakota. ...Texas to Lower Mississippi Valley/Gulf Coast States... A convectively augmented effective front will continue to progress southward, southward-shifting the potential for microburst-related wind damage regionally. Diurnal heating of a moist boundary layer will result in a moderately to strongly unstable and weakly capped airmass by afternoon, with the strongest buoyancy (2500+ J/kg MLCAPE) expected across central/east Texas east-northeastward to Mississippi/western Alabama/southern Tennessee. Some small-scale clusters may evolve, but weak vertical shear will otherwise tend to keep the overall pulse-type damaging wind potential very isolated. ...Northern Plains... The region will be influenced by late-day/nighttime height falls as a shortwave trough emerges eastward from the Canadian Rockies, with an eastward-advancing cold front moving across eastern Montana into North Dakota tonight. A narrow corridor of moderate to large buoyancy is expected along/ahead of the surface cold front, and near a pre-frontal surface trough. Beneath a plume of warm elevated mixed-layer air, mid/upper-level support for the initiation of boundary-layer based thunderstorm development is forecast to generally remain north of the international border. One exception may be in the post-frontal environment across eastern Montana, the environment would be conducive to a few severe storms capable of hail/wind. While the risk for severe thunderstorms appears largely conditional into North Dakota where stronger destabilization is expected, isolated deeper convective development is plausible across northwestern North Dakota in proximity to the surface low/front late this afternoon, and more so this evening. Should this occur, forecast soundings indicate the environment would support isolated supercell development and related severe-weather risks. ..Guyer/Marsh.. 08/20/2025 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0303 AM CDT Wed Aug 20 2025 Valid 231200Z - 281200Z ...DISCUSSION... ...D4/Saturday - D6/Monday... On D4/Saturday, a seasonably strong cold front will move across parts of the south-central Great Plains into the mid MS Valley and southern Great Lakes region, as a deep mid/upper-level trough becomes established over much of the central/eastern CONUS. Somewhat favorable deep-layer flow/shear could support strong to locally severe storms along the front, though generally modest instability may tend to limit the magnitude of the severe threat. Strong storms may also develop within a post-frontal regime across parts of the central High Plains. The cold front will make further south/east progress on D5/Sunday, and locally strong storms may develop from parts of the Northeast into the central/southern Appalachians. Generally weak instability may tend to limit coverage of the organized severe threat. Strong storms may also develop again within a post-frontal regime across parts of the central/southern High Plains. The cold front may tend to slow down by D6/Monday across parts of the Mid Atlantic and Northeast, though guidance begins to diverge regarding the evolution of the deep upper trough and potential for surface low development off of the Mid Atlantic coast. Some potential for strong storms could again evolve along the front, from parts of New England into the Mid Atlantic. ...D7/Tuesday - D8/Wednesday... While predictability continues to wane regarding the details, extended-range guidance generally depicts persistence of the eastern CONUS upper trough into the middle of next week, though it may begin to shift eastward with time. In the wake of the cold frontal passage, an expansive surface ridge is forecast to maintain generally stable conditions for most areas east of the Rockies, resulting in limited potential for organized severe storms. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0303 AM CDT Wed Aug 20 2025 Valid 231200Z - 281200Z ...DISCUSSION... ...D4/Saturday - D6/Monday... On D4/Saturday, a seasonably strong cold front will move across parts of the south-central Great Plains into the mid MS Valley and southern Great Lakes region, as a deep mid/upper-level trough becomes established over much of the central/eastern CONUS. Somewhat favorable deep-layer flow/shear could support strong to locally severe storms along the front, though generally modest instability may tend to limit the magnitude of the severe threat. Strong storms may also develop within a post-frontal regime across parts of the central High Plains. The cold front will make further south/east progress on D5/Sunday, and locally strong storms may develop from parts of the Northeast into the central/southern Appalachians. Generally weak instability may tend to limit coverage of the organized severe threat. Strong storms may also develop again within a post-frontal regime across parts of the central/southern High Plains. The cold front may tend to slow down by D6/Monday across parts of the Mid Atlantic and Northeast, though guidance begins to diverge regarding the evolution of the deep upper trough and potential for surface low development off of the Mid Atlantic coast. Some potential for strong storms could again evolve along the front, from parts of New England into the Mid Atlantic. ...D7/Tuesday - D8/Wednesday... While predictability continues to wane regarding the details, extended-range guidance generally depicts persistence of the eastern CONUS upper trough into the middle of next week, though it may begin to shift eastward with time. In the wake of the cold frontal passage, an expansive surface ridge is forecast to maintain generally stable conditions for most areas east of the Rockies, resulting in limited potential for organized severe storms. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0303 AM CDT Wed Aug 20 2025 Valid 231200Z - 281200Z ...DISCUSSION... ...D4/Saturday - D6/Monday... On D4/Saturday, a seasonably strong cold front will move across parts of the south-central Great Plains into the mid MS Valley and southern Great Lakes region, as a deep mid/upper-level trough becomes established over much of the central/eastern CONUS. Somewhat favorable deep-layer flow/shear could support strong to locally severe storms along the front, though generally modest instability may tend to limit the magnitude of the severe threat. Strong storms may also develop within a post-frontal regime across parts of the central High Plains. The cold front will make further south/east progress on D5/Sunday, and locally strong storms may develop from parts of the Northeast into the central/southern Appalachians. Generally weak instability may tend to limit coverage of the organized severe threat. Strong storms may also develop again within a post-frontal regime across parts of the central/southern High Plains. The cold front may tend to slow down by D6/Monday across parts of the Mid Atlantic and Northeast, though guidance begins to diverge regarding the evolution of the deep upper trough and potential for surface low development off of the Mid Atlantic coast. Some potential for strong storms could again evolve along the front, from parts of New England into the Mid Atlantic. ...D7/Tuesday - D8/Wednesday... While predictability continues to wane regarding the details, extended-range guidance generally depicts persistence of the eastern CONUS upper trough into the middle of next week, though it may begin to shift eastward with time. In the wake of the cold frontal passage, an expansive surface ridge is forecast to maintain generally stable conditions for most areas east of the Rockies, resulting in limited potential for organized severe storms. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0303 AM CDT Wed Aug 20 2025 Valid 231200Z - 281200Z ...DISCUSSION... ...D4/Saturday - D6/Monday... On D4/Saturday, a seasonably strong cold front will move across parts of the south-central Great Plains into the mid MS Valley and southern Great Lakes region, as a deep mid/upper-level trough becomes established over much of the central/eastern CONUS. Somewhat favorable deep-layer flow/shear could support strong to locally severe storms along the front, though generally modest instability may tend to limit the magnitude of the severe threat. Strong storms may also develop within a post-frontal regime across parts of the central High Plains. The cold front will make further south/east progress on D5/Sunday, and locally strong storms may develop from parts of the Northeast into the central/southern Appalachians. Generally weak instability may tend to limit coverage of the organized severe threat. Strong storms may also develop again within a post-frontal regime across parts of the central/southern High Plains. The cold front may tend to slow down by D6/Monday across parts of the Mid Atlantic and Northeast, though guidance begins to diverge regarding the evolution of the deep upper trough and potential for surface low development off of the Mid Atlantic coast. Some potential for strong storms could again evolve along the front, from parts of New England into the Mid Atlantic. ...D7/Tuesday - D8/Wednesday... While predictability continues to wane regarding the details, extended-range guidance generally depicts persistence of the eastern CONUS upper trough into the middle of next week, though it may begin to shift eastward with time. In the wake of the cold frontal passage, an expansive surface ridge is forecast to maintain generally stable conditions for most areas east of the Rockies, resulting in limited potential for organized severe storms. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0303 AM CDT Wed Aug 20 2025 Valid 231200Z - 281200Z ...DISCUSSION... ...D4/Saturday - D6/Monday... On D4/Saturday, a seasonably strong cold front will move across parts of the south-central Great Plains into the mid MS Valley and southern Great Lakes region, as a deep mid/upper-level trough becomes established over much of the central/eastern CONUS. Somewhat favorable deep-layer flow/shear could support strong to locally severe storms along the front, though generally modest instability may tend to limit the magnitude of the severe threat. Strong storms may also develop within a post-frontal regime across parts of the central High Plains. The cold front will make further south/east progress on D5/Sunday, and locally strong storms may develop from parts of the Northeast into the central/southern Appalachians. Generally weak instability may tend to limit coverage of the organized severe threat. Strong storms may also develop again within a post-frontal regime across parts of the central/southern High Plains. The cold front may tend to slow down by D6/Monday across parts of the Mid Atlantic and Northeast, though guidance begins to diverge regarding the evolution of the deep upper trough and potential for surface low development off of the Mid Atlantic coast. Some potential for strong storms could again evolve along the front, from parts of New England into the Mid Atlantic. ...D7/Tuesday - D8/Wednesday... While predictability continues to wane regarding the details, extended-range guidance generally depicts persistence of the eastern CONUS upper trough into the middle of next week, though it may begin to shift eastward with time. In the wake of the cold frontal passage, an expansive surface ridge is forecast to maintain generally stable conditions for most areas east of the Rockies, resulting in limited potential for organized severe storms. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 AM CDT Wed Aug 20 2025 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE CENTRAL/NORTHERN HIGH PLAINS INTO THE UPPER MIDWEST... ...SUMMARY... Strong to locally severe thunderstorms are possible Friday from parts of the central and northern High Plains into the Upper Midwest. ...Northern Great Lakes to the Central High Plains... A seasonably deep mid/upper-level trough is forecast to dig southeastward across parts of the central/northern Plains into the Upper Midwest/Great Lakes on Friday. A surface low is forecast to move across northwest Ontario, as a trailing cold front continues southeastward across parts of the central Plains and Upper Midwest. A secondary cold front is forecast to move across the northern Plains and northern MN, with a much drier airmass expected behind this secondary front. As the mid/upper-level trough digs into the region during the afternoon and evening, isolated to widely scattered storm development will be possible from Upper MI into parts of WI/IA/southeast MN and eastern NE. Relatively weak midlevel lapse rates may tend to limit updraft intensity to some extent, but moderate MLCAPE and 25-35 kt of effective shear within the west-northwesterly flow regime may support some storm organization, with a threat of isolated hail and damaging gusts. Farther west, strong to locally severe storms may develop within a post-frontal regime across parts of eastern WY/CO and the NE Panhandle. Relatively steep midlevel lapse rates could support isolated hail with the strongest storms, with localized strong gusts also possible. ...Arizona... Scattered thunderstorms will again be possible across parts of AZ on Friday, within a similar regime to D2/Thursday. Locally gusty winds will be possible with the strongest storms, along with some potential for outflows to spread into the lower elevations. Trends will be monitored regarding the potential for a greater coverage of damaging gusts. ..Dean.. 08/20/2025 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 AM CDT Wed Aug 20 2025 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE CENTRAL/NORTHERN HIGH PLAINS INTO THE UPPER MIDWEST... ...SUMMARY... Strong to locally severe thunderstorms are possible Friday from parts of the central and northern High Plains into the Upper Midwest. ...Northern Great Lakes to the Central High Plains... A seasonably deep mid/upper-level trough is forecast to dig southeastward across parts of the central/northern Plains into the Upper Midwest/Great Lakes on Friday. A surface low is forecast to move across northwest Ontario, as a trailing cold front continues southeastward across parts of the central Plains and Upper Midwest. A secondary cold front is forecast to move across the northern Plains and northern MN, with a much drier airmass expected behind this secondary front. As the mid/upper-level trough digs into the region during the afternoon and evening, isolated to widely scattered storm development will be possible from Upper MI into parts of WI/IA/southeast MN and eastern NE. Relatively weak midlevel lapse rates may tend to limit updraft intensity to some extent, but moderate MLCAPE and 25-35 kt of effective shear within the west-northwesterly flow regime may support some storm organization, with a threat of isolated hail and damaging gusts. Farther west, strong to locally severe storms may develop within a post-frontal regime across parts of eastern WY/CO and the NE Panhandle. Relatively steep midlevel lapse rates could support isolated hail with the strongest storms, with localized strong gusts also possible. ...Arizona... Scattered thunderstorms will again be possible across parts of AZ on Friday, within a similar regime to D2/Thursday. Locally gusty winds will be possible with the strongest storms, along with some potential for outflows to spread into the lower elevations. Trends will be monitored regarding the potential for a greater coverage of damaging gusts. ..Dean.. 08/20/2025 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 AM CDT Wed Aug 20 2025 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE CENTRAL/NORTHERN HIGH PLAINS INTO THE UPPER MIDWEST... ...SUMMARY... Strong to locally severe thunderstorms are possible Friday from parts of the central and northern High Plains into the Upper Midwest. ...Northern Great Lakes to the Central High Plains... A seasonably deep mid/upper-level trough is forecast to dig southeastward across parts of the central/northern Plains into the Upper Midwest/Great Lakes on Friday. A surface low is forecast to move across northwest Ontario, as a trailing cold front continues southeastward across parts of the central Plains and Upper Midwest. A secondary cold front is forecast to move across the northern Plains and northern MN, with a much drier airmass expected behind this secondary front. As the mid/upper-level trough digs into the region during the afternoon and evening, isolated to widely scattered storm development will be possible from Upper MI into parts of WI/IA/southeast MN and eastern NE. Relatively weak midlevel lapse rates may tend to limit updraft intensity to some extent, but moderate MLCAPE and 25-35 kt of effective shear within the west-northwesterly flow regime may support some storm organization, with a threat of isolated hail and damaging gusts. Farther west, strong to locally severe storms may develop within a post-frontal regime across parts of eastern WY/CO and the NE Panhandle. Relatively steep midlevel lapse rates could support isolated hail with the strongest storms, with localized strong gusts also possible. ...Arizona... Scattered thunderstorms will again be possible across parts of AZ on Friday, within a similar regime to D2/Thursday. Locally gusty winds will be possible with the strongest storms, along with some potential for outflows to spread into the lower elevations. Trends will be monitored regarding the potential for a greater coverage of damaging gusts. ..Dean.. 08/20/2025 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 AM CDT Wed Aug 20 2025 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE CENTRAL/NORTHERN HIGH PLAINS INTO THE UPPER MIDWEST... ...SUMMARY... Strong to locally severe thunderstorms are possible Friday from parts of the central and northern High Plains into the Upper Midwest. ...Northern Great Lakes to the Central High Plains... A seasonably deep mid/upper-level trough is forecast to dig southeastward across parts of the central/northern Plains into the Upper Midwest/Great Lakes on Friday. A surface low is forecast to move across northwest Ontario, as a trailing cold front continues southeastward across parts of the central Plains and Upper Midwest. A secondary cold front is forecast to move across the northern Plains and northern MN, with a much drier airmass expected behind this secondary front. As the mid/upper-level trough digs into the region during the afternoon and evening, isolated to widely scattered storm development will be possible from Upper MI into parts of WI/IA/southeast MN and eastern NE. Relatively weak midlevel lapse rates may tend to limit updraft intensity to some extent, but moderate MLCAPE and 25-35 kt of effective shear within the west-northwesterly flow regime may support some storm organization, with a threat of isolated hail and damaging gusts. Farther west, strong to locally severe storms may develop within a post-frontal regime across parts of eastern WY/CO and the NE Panhandle. Relatively steep midlevel lapse rates could support isolated hail with the strongest storms, with localized strong gusts also possible. ...Arizona... Scattered thunderstorms will again be possible across parts of AZ on Friday, within a similar regime to D2/Thursday. Locally gusty winds will be possible with the strongest storms, along with some potential for outflows to spread into the lower elevations. Trends will be monitored regarding the potential for a greater coverage of damaging gusts. ..Dean.. 08/20/2025 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 AM CDT Wed Aug 20 2025 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE CENTRAL/NORTHERN HIGH PLAINS INTO THE UPPER MIDWEST... ...SUMMARY... Strong to locally severe thunderstorms are possible Friday from parts of the central and northern High Plains into the Upper Midwest. ...Northern Great Lakes to the Central High Plains... A seasonably deep mid/upper-level trough is forecast to dig southeastward across parts of the central/northern Plains into the Upper Midwest/Great Lakes on Friday. A surface low is forecast to move across northwest Ontario, as a trailing cold front continues southeastward across parts of the central Plains and Upper Midwest. A secondary cold front is forecast to move across the northern Plains and northern MN, with a much drier airmass expected behind this secondary front. As the mid/upper-level trough digs into the region during the afternoon and evening, isolated to widely scattered storm development will be possible from Upper MI into parts of WI/IA/southeast MN and eastern NE. Relatively weak midlevel lapse rates may tend to limit updraft intensity to some extent, but moderate MLCAPE and 25-35 kt of effective shear within the west-northwesterly flow regime may support some storm organization, with a threat of isolated hail and damaging gusts. Farther west, strong to locally severe storms may develop within a post-frontal regime across parts of eastern WY/CO and the NE Panhandle. Relatively steep midlevel lapse rates could support isolated hail with the strongest storms, with localized strong gusts also possible. ...Arizona... Scattered thunderstorms will again be possible across parts of AZ on Friday, within a similar regime to D2/Thursday. Locally gusty winds will be possible with the strongest storms, along with some potential for outflows to spread into the lower elevations. Trends will be monitored regarding the potential for a greater coverage of damaging gusts. ..Dean.. 08/20/2025 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0157 AM CDT Wed Aug 20 2025 Valid 211200Z - 221200Z ...Synopsis... The strong ridge over the western US is expected to continue to break down under the shortwave trough passing through the northern Rockies. This will support continued advection of monsoon moisture northward into the Great Basin and parts of southern California. By Thursday afternoon, PWAT values are likely to be between 0.5-0.8" with a dry sub-cloud layer and steep low-level lapse rates. Despite slower storm motions and isolated coverage over Utah and parts of Nevada, little wetting rainfall is expected. This should support isolated dry thunderstorm potential the under the upper high and into portions of eastern Idaho and western Wyoming. With dry fuels in place, some lightning ignitions are possible. In addition to the potential for thunderstorms, very warm and unstable conditions are expected on the periphery of the deeper monsoon moisture surge over parts of the southern Great Basin and southern California. Steep mid-level lapse rates and marginal buoyancy will support unstable conditions over much of the Southwest. This could support plume dominated fire growth and pyroconvection near large active fires, with localized extreme fire behavior possible. ..Lyons.. 08/20/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0157 AM CDT Wed Aug 20 2025 Valid 211200Z - 221200Z ...Synopsis... The strong ridge over the western US is expected to continue to break down under the shortwave trough passing through the northern Rockies. This will support continued advection of monsoon moisture northward into the Great Basin and parts of southern California. By Thursday afternoon, PWAT values are likely to be between 0.5-0.8" with a dry sub-cloud layer and steep low-level lapse rates. Despite slower storm motions and isolated coverage over Utah and parts of Nevada, little wetting rainfall is expected. This should support isolated dry thunderstorm potential the under the upper high and into portions of eastern Idaho and western Wyoming. With dry fuels in place, some lightning ignitions are possible. In addition to the potential for thunderstorms, very warm and unstable conditions are expected on the periphery of the deeper monsoon moisture surge over parts of the southern Great Basin and southern California. Steep mid-level lapse rates and marginal buoyancy will support unstable conditions over much of the Southwest. This could support plume dominated fire growth and pyroconvection near large active fires, with localized extreme fire behavior possible. ..Lyons.. 08/20/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0157 AM CDT Wed Aug 20 2025 Valid 211200Z - 221200Z ...Synopsis... The strong ridge over the western US is expected to continue to break down under the shortwave trough passing through the northern Rockies. This will support continued advection of monsoon moisture northward into the Great Basin and parts of southern California. By Thursday afternoon, PWAT values are likely to be between 0.5-0.8" with a dry sub-cloud layer and steep low-level lapse rates. Despite slower storm motions and isolated coverage over Utah and parts of Nevada, little wetting rainfall is expected. This should support isolated dry thunderstorm potential the under the upper high and into portions of eastern Idaho and western Wyoming. With dry fuels in place, some lightning ignitions are possible. In addition to the potential for thunderstorms, very warm and unstable conditions are expected on the periphery of the deeper monsoon moisture surge over parts of the southern Great Basin and southern California. Steep mid-level lapse rates and marginal buoyancy will support unstable conditions over much of the Southwest. This could support plume dominated fire growth and pyroconvection near large active fires, with localized extreme fire behavior possible. ..Lyons.. 08/20/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0157 AM CDT Wed Aug 20 2025 Valid 211200Z - 221200Z ...Synopsis... The strong ridge over the western US is expected to continue to break down under the shortwave trough passing through the northern Rockies. This will support continued advection of monsoon moisture northward into the Great Basin and parts of southern California. By Thursday afternoon, PWAT values are likely to be between 0.5-0.8" with a dry sub-cloud layer and steep low-level lapse rates. Despite slower storm motions and isolated coverage over Utah and parts of Nevada, little wetting rainfall is expected. This should support isolated dry thunderstorm potential the under the upper high and into portions of eastern Idaho and western Wyoming. With dry fuels in place, some lightning ignitions are possible. In addition to the potential for thunderstorms, very warm and unstable conditions are expected on the periphery of the deeper monsoon moisture surge over parts of the southern Great Basin and southern California. Steep mid-level lapse rates and marginal buoyancy will support unstable conditions over much of the Southwest. This could support plume dominated fire growth and pyroconvection near large active fires, with localized extreme fire behavior possible. ..Lyons.. 08/20/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0156 AM CDT Wed Aug 20 2025 Valid 201200Z - 211200Z ...Synopsis... A strong ridge of high pressure building over the central US is forecast to gradually move west while a weak trough on the western edge, suppresses the northern extent. The increasingly strong height gradient along the western periphery of the ridge will bolster mid-level winds aloft over the Northwest and northern Great Basin. At the surface, a cold front will move into the western Great Basin before stalling this afternoon. The front, and increased flow aloft will support gusty surface winds and isolated storms, increasing fire danger today and tonight. ...Great Basin... Several hours of dry/breezy conditions are expected this afternoon with the breakdown of the upper-level ridge. Very warm temperatures are expected, supporting deep vertical mixing and low boundary-layer RH. West/southwesterly winds of 15-20 mph with gusts of 20-30 mph near the front, and RH below 15% on a widespread basis will support elevated to locally critical fire-weather conditions from southern ID into the Great Basin. Increased southwesterly flow aloft on the western edge of the ridge will help monsoon moisture (PWATs 0.6-0.8 inches) advect northward over NV and western UT. The surface cold front associated with the upper trough will stall over the western Great Basin, serving as a focus for isolated thunderstorm development through the afternoon. Uncertainty remains high regarding coverage of thunderstorms, especially with southern extent. While moisture and instability will be more limited, enough instability and forcing are expected to produce isolated high-based showers and thunderstorms capable of dry lightning. Should these storms develop they may track eastward, persisting overnight into eastern ID and western MT with a continued threat for dry strikes. Additionally, any active large wildfires may have increased chances of deep pyroconvection/localized extreme fire behavior given the steep lapse rates and unstable troposphere. ..Lyons.. 08/20/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0156 AM CDT Wed Aug 20 2025 Valid 201200Z - 211200Z ...Synopsis... A strong ridge of high pressure building over the central US is forecast to gradually move west while a weak trough on the western edge, suppresses the northern extent. The increasingly strong height gradient along the western periphery of the ridge will bolster mid-level winds aloft over the Northwest and northern Great Basin. At the surface, a cold front will move into the western Great Basin before stalling this afternoon. The front, and increased flow aloft will support gusty surface winds and isolated storms, increasing fire danger today and tonight. ...Great Basin... Several hours of dry/breezy conditions are expected this afternoon with the breakdown of the upper-level ridge. Very warm temperatures are expected, supporting deep vertical mixing and low boundary-layer RH. West/southwesterly winds of 15-20 mph with gusts of 20-30 mph near the front, and RH below 15% on a widespread basis will support elevated to locally critical fire-weather conditions from southern ID into the Great Basin. Increased southwesterly flow aloft on the western edge of the ridge will help monsoon moisture (PWATs 0.6-0.8 inches) advect northward over NV and western UT. The surface cold front associated with the upper trough will stall over the western Great Basin, serving as a focus for isolated thunderstorm development through the afternoon. Uncertainty remains high regarding coverage of thunderstorms, especially with southern extent. While moisture and instability will be more limited, enough instability and forcing are expected to produce isolated high-based showers and thunderstorms capable of dry lightning. Should these storms develop they may track eastward, persisting overnight into eastern ID and western MT with a continued threat for dry strikes. Additionally, any active large wildfires may have increased chances of deep pyroconvection/localized extreme fire behavior given the steep lapse rates and unstable troposphere. ..Lyons.. 08/20/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0156 AM CDT Wed Aug 20 2025 Valid 201200Z - 211200Z ...Synopsis... A strong ridge of high pressure building over the central US is forecast to gradually move west while a weak trough on the western edge, suppresses the northern extent. The increasingly strong height gradient along the western periphery of the ridge will bolster mid-level winds aloft over the Northwest and northern Great Basin. At the surface, a cold front will move into the western Great Basin before stalling this afternoon. The front, and increased flow aloft will support gusty surface winds and isolated storms, increasing fire danger today and tonight. ...Great Basin... Several hours of dry/breezy conditions are expected this afternoon with the breakdown of the upper-level ridge. Very warm temperatures are expected, supporting deep vertical mixing and low boundary-layer RH. West/southwesterly winds of 15-20 mph with gusts of 20-30 mph near the front, and RH below 15% on a widespread basis will support elevated to locally critical fire-weather conditions from southern ID into the Great Basin. Increased southwesterly flow aloft on the western edge of the ridge will help monsoon moisture (PWATs 0.6-0.8 inches) advect northward over NV and western UT. The surface cold front associated with the upper trough will stall over the western Great Basin, serving as a focus for isolated thunderstorm development through the afternoon. Uncertainty remains high regarding coverage of thunderstorms, especially with southern extent. While moisture and instability will be more limited, enough instability and forcing are expected to produce isolated high-based showers and thunderstorms capable of dry lightning. Should these storms develop they may track eastward, persisting overnight into eastern ID and western MT with a continued threat for dry strikes. Additionally, any active large wildfires may have increased chances of deep pyroconvection/localized extreme fire behavior given the steep lapse rates and unstable troposphere. ..Lyons.. 08/20/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0156 AM CDT Wed Aug 20 2025 Valid 201200Z - 211200Z ...Synopsis... A strong ridge of high pressure building over the central US is forecast to gradually move west while a weak trough on the western edge, suppresses the northern extent. The increasingly strong height gradient along the western periphery of the ridge will bolster mid-level winds aloft over the Northwest and northern Great Basin. At the surface, a cold front will move into the western Great Basin before stalling this afternoon. The front, and increased flow aloft will support gusty surface winds and isolated storms, increasing fire danger today and tonight. ...Great Basin... Several hours of dry/breezy conditions are expected this afternoon with the breakdown of the upper-level ridge. Very warm temperatures are expected, supporting deep vertical mixing and low boundary-layer RH. West/southwesterly winds of 15-20 mph with gusts of 20-30 mph near the front, and RH below 15% on a widespread basis will support elevated to locally critical fire-weather conditions from southern ID into the Great Basin. Increased southwesterly flow aloft on the western edge of the ridge will help monsoon moisture (PWATs 0.6-0.8 inches) advect northward over NV and western UT. The surface cold front associated with the upper trough will stall over the western Great Basin, serving as a focus for isolated thunderstorm development through the afternoon. Uncertainty remains high regarding coverage of thunderstorms, especially with southern extent. While moisture and instability will be more limited, enough instability and forcing are expected to produce isolated high-based showers and thunderstorms capable of dry lightning. Should these storms develop they may track eastward, persisting overnight into eastern ID and western MT with a continued threat for dry strikes. Additionally, any active large wildfires may have increased chances of deep pyroconvection/localized extreme fire behavior given the steep lapse rates and unstable troposphere. ..Lyons.. 08/20/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more