Severe Storms

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Fri Aug 22 2025 Valid 221200Z - 231200Z ...Synopsis... An expansive midlevel ridge will remain in place across much of the West, while a well-established monsoonal moisture plume persists across the Southwest into the Great Basin. ...Dry Thunderstorms... Diurnal heating/boundary-layer mixing amid the monsoonal moisture will yield sufficient buoyancy for isolated to widely scattered thunderstorms across a broad region extending from the Sierra into the Great Basin and central Rockies during the afternoon/evening. Inverted-V profiles, characterized by 0.70 to 0.90 inch PW, will favor a mix of wet/dry high-based storms -- posing a risk of lightning-induced ignitions and gusty/erratic outflow winds over dry/receptive fuels. ...North-central Oregon... Along the northern periphery of surface high pressure over the Southwest/Great Basin, a modest offshore pressure gradient will develop across the Northwest. As a result, breezy/gusty east-northeasterly surface winds are expected amid 15-percent RH across north-central OR, with locally enhanced winds expected through the Columbia Gorge. Given dry fuels, elevated fire-weather conditions are expected. ...Coastal New England... On the far western fringes of Hurricane Erin, dry/breezy northerly winds atop receptive fuels will favor elevated fire-weather conditions across coastal New England during the afternoon. ...Southern California... An unseasonably hot and unstable air mass along with critically dry fuels will continue to promote elevated fire-weather conditions away from the coast in southern CA, despite only modest surface winds. Additionally, isolated high-based thunderstorms will pose a localized risk of lightning-induced ignitions and gusty/erratic winds away from any heavier rain cores. ..Weinman.. 08/22/2025 ...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 0159 AM CDT Fri Aug 22 2025 Valid 221200Z - 231200Z ...Synopsis... An expansive midlevel ridge will remain in place across much of the West, while a well-established monsoonal moisture plume persists across the Southwest into the Great Basin. ...Dry Thunderstorms... Diurnal heating/boundary-layer mixing amid the monsoonal moisture will yield sufficient buoyancy for isolated to widely scattered thunderstorms across a broad region extending from the Sierra into the Great Basin and central Rockies during the afternoon/evening. Inverted-V profiles, characterized by 0.70 to 0.90 inch PW, will favor a mix of wet/dry high-based storms -- posing a risk of lightning-induced ignitions and gusty/erratic outflow winds over dry/receptive fuels. ...North-central Oregon... Along the northern periphery of surface high pressure over the Southwest/Great Basin, a modest offshore pressure gradient will develop across the Northwest. As a result, breezy/gusty east-northeasterly surface winds are expected amid 15-percent RH across north-central OR, with locally enhanced winds expected through the Columbia Gorge. Given dry fuels, elevated fire-weather conditions are expected. ...Coastal New England... On the far western fringes of Hurricane Erin, dry/breezy northerly winds atop receptive fuels will favor elevated fire-weather conditions across coastal New England during the afternoon. ...Southern California... An unseasonably hot and unstable air mass along with critically dry fuels will continue to promote elevated fire-weather conditions away from the coast in southern CA, despite only modest surface winds. Additionally, isolated high-based thunderstorms will pose a localized risk of lightning-induced ignitions and gusty/erratic winds away from any heavier rain cores. ..Weinman.. 08/22/2025 ...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 0159 AM CDT Fri Aug 22 2025 Valid 221200Z - 231200Z ...Synopsis... An expansive midlevel ridge will remain in place across much of the West, while a well-established monsoonal moisture plume persists across the Southwest into the Great Basin. ...Dry Thunderstorms... Diurnal heating/boundary-layer mixing amid the monsoonal moisture will yield sufficient buoyancy for isolated to widely scattered thunderstorms across a broad region extending from the Sierra into the Great Basin and central Rockies during the afternoon/evening. Inverted-V profiles, characterized by 0.70 to 0.90 inch PW, will favor a mix of wet/dry high-based storms -- posing a risk of lightning-induced ignitions and gusty/erratic outflow winds over dry/receptive fuels. ...North-central Oregon... Along the northern periphery of surface high pressure over the Southwest/Great Basin, a modest offshore pressure gradient will develop across the Northwest. As a result, breezy/gusty east-northeasterly surface winds are expected amid 15-percent RH across north-central OR, with locally enhanced winds expected through the Columbia Gorge. Given dry fuels, elevated fire-weather conditions are expected. ...Coastal New England... On the far western fringes of Hurricane Erin, dry/breezy northerly winds atop receptive fuels will favor elevated fire-weather conditions across coastal New England during the afternoon. ...Southern California... An unseasonably hot and unstable air mass along with critically dry fuels will continue to promote elevated fire-weather conditions away from the coast in southern CA, despite only modest surface winds. Additionally, isolated high-based thunderstorms will pose a localized risk of lightning-induced ignitions and gusty/erratic winds away from any heavier rain cores. ..Weinman.. 08/22/2025 ...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 0159 AM CDT Fri Aug 22 2025 Valid 221200Z - 231200Z ...Synopsis... An expansive midlevel ridge will remain in place across much of the West, while a well-established monsoonal moisture plume persists across the Southwest into the Great Basin. ...Dry Thunderstorms... Diurnal heating/boundary-layer mixing amid the monsoonal moisture will yield sufficient buoyancy for isolated to widely scattered thunderstorms across a broad region extending from the Sierra into the Great Basin and central Rockies during the afternoon/evening. Inverted-V profiles, characterized by 0.70 to 0.90 inch PW, will favor a mix of wet/dry high-based storms -- posing a risk of lightning-induced ignitions and gusty/erratic outflow winds over dry/receptive fuels. ...North-central Oregon... Along the northern periphery of surface high pressure over the Southwest/Great Basin, a modest offshore pressure gradient will develop across the Northwest. As a result, breezy/gusty east-northeasterly surface winds are expected amid 15-percent RH across north-central OR, with locally enhanced winds expected through the Columbia Gorge. Given dry fuels, elevated fire-weather conditions are expected. ...Coastal New England... On the far western fringes of Hurricane Erin, dry/breezy northerly winds atop receptive fuels will favor elevated fire-weather conditions across coastal New England during the afternoon. ...Southern California... An unseasonably hot and unstable air mass along with critically dry fuels will continue to promote elevated fire-weather conditions away from the coast in southern CA, despite only modest surface winds. Additionally, isolated high-based thunderstorms will pose a localized risk of lightning-induced ignitions and gusty/erratic winds away from any heavier rain cores. ..Weinman.. 08/22/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1257 AM CDT Fri Aug 22 2025 Valid 231200Z - 241200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The potential for severe storms is low across the continental U.S. for Saturday or Saturday night. ...DISCUSSION... A mid-level shortwave trough will move eastward through the western Great Lakes on Saturday, as a cold front advances southeastward across the mid Mississippi Valley and central Plains. As surface temperatures warm during the day, isolated thunderstorm development will be possible near the front. Instability is expected to remain weak along and ahead of the front, which should keep any severe potential low. Elsewhere across the continental U.S., no severe threat is expected. ..Broyles.. 08/22/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1257 AM CDT Fri Aug 22 2025 Valid 231200Z - 241200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The potential for severe storms is low across the continental U.S. for Saturday or Saturday night. ...DISCUSSION... A mid-level shortwave trough will move eastward through the western Great Lakes on Saturday, as a cold front advances southeastward across the mid Mississippi Valley and central Plains. As surface temperatures warm during the day, isolated thunderstorm development will be possible near the front. Instability is expected to remain weak along and ahead of the front, which should keep any severe potential low. Elsewhere across the continental U.S., no severe threat is expected. ..Broyles.. 08/22/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1257 AM CDT Fri Aug 22 2025 Valid 231200Z - 241200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The potential for severe storms is low across the continental U.S. for Saturday or Saturday night. ...DISCUSSION... A mid-level shortwave trough will move eastward through the western Great Lakes on Saturday, as a cold front advances southeastward across the mid Mississippi Valley and central Plains. As surface temperatures warm during the day, isolated thunderstorm development will be possible near the front. Instability is expected to remain weak along and ahead of the front, which should keep any severe potential low. Elsewhere across the continental U.S., no severe threat is expected. ..Broyles.. 08/22/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1257 AM CDT Fri Aug 22 2025 Valid 231200Z - 241200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The potential for severe storms is low across the continental U.S. for Saturday or Saturday night. ...DISCUSSION... A mid-level shortwave trough will move eastward through the western Great Lakes on Saturday, as a cold front advances southeastward across the mid Mississippi Valley and central Plains. As surface temperatures warm during the day, isolated thunderstorm development will be possible near the front. Instability is expected to remain weak along and ahead of the front, which should keep any severe potential low. Elsewhere across the continental U.S., no severe threat is expected. ..Broyles.. 08/22/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1257 AM CDT Fri Aug 22 2025 Valid 231200Z - 241200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The potential for severe storms is low across the continental U.S. for Saturday or Saturday night. ...DISCUSSION... A mid-level shortwave trough will move eastward through the western Great Lakes on Saturday, as a cold front advances southeastward across the mid Mississippi Valley and central Plains. As surface temperatures warm during the day, isolated thunderstorm development will be possible near the front. Instability is expected to remain weak along and ahead of the front, which should keep any severe potential low. Elsewhere across the continental U.S., no severe threat is expected. ..Broyles.. 08/22/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1257 AM CDT Fri Aug 22 2025 Valid 231200Z - 241200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The potential for severe storms is low across the continental U.S. for Saturday or Saturday night. ...DISCUSSION... A mid-level shortwave trough will move eastward through the western Great Lakes on Saturday, as a cold front advances southeastward across the mid Mississippi Valley and central Plains. As surface temperatures warm during the day, isolated thunderstorm development will be possible near the front. Instability is expected to remain weak along and ahead of the front, which should keep any severe potential low. Elsewhere across the continental U.S., no severe threat is expected. ..Broyles.. 08/22/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1239 AM CDT Fri Aug 22 2025 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL/NORTHERN HIGH PLAINS AND UPPER MIDWEST AND OVER PARTS OF THE SOUTHWESTERN UNITED STATES... ...SUMMARY... Strong to locally severe thunderstorms are possible from parts of the central and northern High Plains into the Upper Midwest, and across parts of the southwestern United States. ...Central/Northern High Plains-Upper Midwest... Central Canadian upper trough is forecast to advance into western ON/MN by 23/00z as 500mb speed max settles into the base of the trough over the upper Red River region of eastern ND/MN. High-level diffluent flow will be noted across much of the Upper Midwest ahead of this feature which will encourage deep convection along the frontal zone from the upper Great Lakes into portions of the Mid MO Valley. Early in the period, remnant MCS activity may be ongoing across southern MN/southeast SD. However, left-over convective debris may also inhibit surface heating, but may enhance an afternoon boundary for potential thunderstorm development. Latest model guidance suggests the front may be multi faceted with some of the stronger boundary-layer heating expected behind the initial wind shift across SD into northern MN - well northwest of high PW air mass. As a result, forecast soundings suggest surface parcels may struggle to reach convective temperature along the leading wind shift, with only modest lapse rates expected. Even so, deep-layer shear will be more than adequate for sustaining organized updrafts where frontal convergence aids convective development. Higher confidence in robust convection is expected across portions of CO into southeast WY. Strong surface heating should aid thunderstorm development across the higher terrain, along the northern periphery of the Four Corners upper high. This activity should propagate southeast toward lower elevations where it will encounter favorably moist, but weak upslope flow. Hail and wind are possible with this activity. ...Arizona... Upper high is forecast to shift slowly west across southern UT during the day1 period. This will ensure modest easterly 500mb flow across the southern half of AZ. Strong boundary-layer heating will once again prove instrumental in convective development over the higher terrain. This activity will spread toward the lower deserts during the evening with an attendant risk for at least locally severe wind gusts. ..Darrow/Weinman.. 08/22/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1239 AM CDT Fri Aug 22 2025 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL/NORTHERN HIGH PLAINS AND UPPER MIDWEST AND OVER PARTS OF THE SOUTHWESTERN UNITED STATES... ...SUMMARY... Strong to locally severe thunderstorms are possible from parts of the central and northern High Plains into the Upper Midwest, and across parts of the southwestern United States. ...Central/Northern High Plains-Upper Midwest... Central Canadian upper trough is forecast to advance into western ON/MN by 23/00z as 500mb speed max settles into the base of the trough over the upper Red River region of eastern ND/MN. High-level diffluent flow will be noted across much of the Upper Midwest ahead of this feature which will encourage deep convection along the frontal zone from the upper Great Lakes into portions of the Mid MO Valley. Early in the period, remnant MCS activity may be ongoing across southern MN/southeast SD. However, left-over convective debris may also inhibit surface heating, but may enhance an afternoon boundary for potential thunderstorm development. Latest model guidance suggests the front may be multi faceted with some of the stronger boundary-layer heating expected behind the initial wind shift across SD into northern MN - well northwest of high PW air mass. As a result, forecast soundings suggest surface parcels may struggle to reach convective temperature along the leading wind shift, with only modest lapse rates expected. Even so, deep-layer shear will be more than adequate for sustaining organized updrafts where frontal convergence aids convective development. Higher confidence in robust convection is expected across portions of CO into southeast WY. Strong surface heating should aid thunderstorm development across the higher terrain, along the northern periphery of the Four Corners upper high. This activity should propagate southeast toward lower elevations where it will encounter favorably moist, but weak upslope flow. Hail and wind are possible with this activity. ...Arizona... Upper high is forecast to shift slowly west across southern UT during the day1 period. This will ensure modest easterly 500mb flow across the southern half of AZ. Strong boundary-layer heating will once again prove instrumental in convective development over the higher terrain. This activity will spread toward the lower deserts during the evening with an attendant risk for at least locally severe wind gusts. ..Darrow/Weinman.. 08/22/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1239 AM CDT Fri Aug 22 2025 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL/NORTHERN HIGH PLAINS AND UPPER MIDWEST AND OVER PARTS OF THE SOUTHWESTERN UNITED STATES... ...SUMMARY... Strong to locally severe thunderstorms are possible from parts of the central and northern High Plains into the Upper Midwest, and across parts of the southwestern United States. ...Central/Northern High Plains-Upper Midwest... Central Canadian upper trough is forecast to advance into western ON/MN by 23/00z as 500mb speed max settles into the base of the trough over the upper Red River region of eastern ND/MN. High-level diffluent flow will be noted across much of the Upper Midwest ahead of this feature which will encourage deep convection along the frontal zone from the upper Great Lakes into portions of the Mid MO Valley. Early in the period, remnant MCS activity may be ongoing across southern MN/southeast SD. However, left-over convective debris may also inhibit surface heating, but may enhance an afternoon boundary for potential thunderstorm development. Latest model guidance suggests the front may be multi faceted with some of the stronger boundary-layer heating expected behind the initial wind shift across SD into northern MN - well northwest of high PW air mass. As a result, forecast soundings suggest surface parcels may struggle to reach convective temperature along the leading wind shift, with only modest lapse rates expected. Even so, deep-layer shear will be more than adequate for sustaining organized updrafts where frontal convergence aids convective development. Higher confidence in robust convection is expected across portions of CO into southeast WY. Strong surface heating should aid thunderstorm development across the higher terrain, along the northern periphery of the Four Corners upper high. This activity should propagate southeast toward lower elevations where it will encounter favorably moist, but weak upslope flow. Hail and wind are possible with this activity. ...Arizona... Upper high is forecast to shift slowly west across southern UT during the day1 period. This will ensure modest easterly 500mb flow across the southern half of AZ. Strong boundary-layer heating will once again prove instrumental in convective development over the higher terrain. This activity will spread toward the lower deserts during the evening with an attendant risk for at least locally severe wind gusts. ..Darrow/Weinman.. 08/22/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1239 AM CDT Fri Aug 22 2025 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL/NORTHERN HIGH PLAINS AND UPPER MIDWEST AND OVER PARTS OF THE SOUTHWESTERN UNITED STATES... ...SUMMARY... Strong to locally severe thunderstorms are possible from parts of the central and northern High Plains into the Upper Midwest, and across parts of the southwestern United States. ...Central/Northern High Plains-Upper Midwest... Central Canadian upper trough is forecast to advance into western ON/MN by 23/00z as 500mb speed max settles into the base of the trough over the upper Red River region of eastern ND/MN. High-level diffluent flow will be noted across much of the Upper Midwest ahead of this feature which will encourage deep convection along the frontal zone from the upper Great Lakes into portions of the Mid MO Valley. Early in the period, remnant MCS activity may be ongoing across southern MN/southeast SD. However, left-over convective debris may also inhibit surface heating, but may enhance an afternoon boundary for potential thunderstorm development. Latest model guidance suggests the front may be multi faceted with some of the stronger boundary-layer heating expected behind the initial wind shift across SD into northern MN - well northwest of high PW air mass. As a result, forecast soundings suggest surface parcels may struggle to reach convective temperature along the leading wind shift, with only modest lapse rates expected. Even so, deep-layer shear will be more than adequate for sustaining organized updrafts where frontal convergence aids convective development. Higher confidence in robust convection is expected across portions of CO into southeast WY. Strong surface heating should aid thunderstorm development across the higher terrain, along the northern periphery of the Four Corners upper high. This activity should propagate southeast toward lower elevations where it will encounter favorably moist, but weak upslope flow. Hail and wind are possible with this activity. ...Arizona... Upper high is forecast to shift slowly west across southern UT during the day1 period. This will ensure modest easterly 500mb flow across the southern half of AZ. Strong boundary-layer heating will once again prove instrumental in convective development over the higher terrain. This activity will spread toward the lower deserts during the evening with an attendant risk for at least locally severe wind gusts. ..Darrow/Weinman.. 08/22/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1239 AM CDT Fri Aug 22 2025 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL/NORTHERN HIGH PLAINS AND UPPER MIDWEST AND OVER PARTS OF THE SOUTHWESTERN UNITED STATES... ...SUMMARY... Strong to locally severe thunderstorms are possible from parts of the central and northern High Plains into the Upper Midwest, and across parts of the southwestern United States. ...Central/Northern High Plains-Upper Midwest... Central Canadian upper trough is forecast to advance into western ON/MN by 23/00z as 500mb speed max settles into the base of the trough over the upper Red River region of eastern ND/MN. High-level diffluent flow will be noted across much of the Upper Midwest ahead of this feature which will encourage deep convection along the frontal zone from the upper Great Lakes into portions of the Mid MO Valley. Early in the period, remnant MCS activity may be ongoing across southern MN/southeast SD. However, left-over convective debris may also inhibit surface heating, but may enhance an afternoon boundary for potential thunderstorm development. Latest model guidance suggests the front may be multi faceted with some of the stronger boundary-layer heating expected behind the initial wind shift across SD into northern MN - well northwest of high PW air mass. As a result, forecast soundings suggest surface parcels may struggle to reach convective temperature along the leading wind shift, with only modest lapse rates expected. Even so, deep-layer shear will be more than adequate for sustaining organized updrafts where frontal convergence aids convective development. Higher confidence in robust convection is expected across portions of CO into southeast WY. Strong surface heating should aid thunderstorm development across the higher terrain, along the northern periphery of the Four Corners upper high. This activity should propagate southeast toward lower elevations where it will encounter favorably moist, but weak upslope flow. Hail and wind are possible with this activity. ...Arizona... Upper high is forecast to shift slowly west across southern UT during the day1 period. This will ensure modest easterly 500mb flow across the southern half of AZ. Strong boundary-layer heating will once again prove instrumental in convective development over the higher terrain. This activity will spread toward the lower deserts during the evening with an attendant risk for at least locally severe wind gusts. ..Darrow/Weinman.. 08/22/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1239 AM CDT Fri Aug 22 2025 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL/NORTHERN HIGH PLAINS AND UPPER MIDWEST AND OVER PARTS OF THE SOUTHWESTERN UNITED STATES... ...SUMMARY... Strong to locally severe thunderstorms are possible from parts of the central and northern High Plains into the Upper Midwest, and across parts of the southwestern United States. ...Central/Northern High Plains-Upper Midwest... Central Canadian upper trough is forecast to advance into western ON/MN by 23/00z as 500mb speed max settles into the base of the trough over the upper Red River region of eastern ND/MN. High-level diffluent flow will be noted across much of the Upper Midwest ahead of this feature which will encourage deep convection along the frontal zone from the upper Great Lakes into portions of the Mid MO Valley. Early in the period, remnant MCS activity may be ongoing across southern MN/southeast SD. However, left-over convective debris may also inhibit surface heating, but may enhance an afternoon boundary for potential thunderstorm development. Latest model guidance suggests the front may be multi faceted with some of the stronger boundary-layer heating expected behind the initial wind shift across SD into northern MN - well northwest of high PW air mass. As a result, forecast soundings suggest surface parcels may struggle to reach convective temperature along the leading wind shift, with only modest lapse rates expected. Even so, deep-layer shear will be more than adequate for sustaining organized updrafts where frontal convergence aids convective development. Higher confidence in robust convection is expected across portions of CO into southeast WY. Strong surface heating should aid thunderstorm development across the higher terrain, along the northern periphery of the Four Corners upper high. This activity should propagate southeast toward lower elevations where it will encounter favorably moist, but weak upslope flow. Hail and wind are possible with this activity. ...Arizona... Upper high is forecast to shift slowly west across southern UT during the day1 period. This will ensure modest easterly 500mb flow across the southern half of AZ. Strong boundary-layer heating will once again prove instrumental in convective development over the higher terrain. This activity will spread toward the lower deserts during the evening with an attendant risk for at least locally severe wind gusts. ..Darrow/Weinman.. 08/22/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1239 AM CDT Fri Aug 22 2025 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL/NORTHERN HIGH PLAINS AND UPPER MIDWEST AND OVER PARTS OF THE SOUTHWESTERN UNITED STATES... ...SUMMARY... Strong to locally severe thunderstorms are possible from parts of the central and northern High Plains into the Upper Midwest, and across parts of the southwestern United States. ...Central/Northern High Plains-Upper Midwest... Central Canadian upper trough is forecast to advance into western ON/MN by 23/00z as 500mb speed max settles into the base of the trough over the upper Red River region of eastern ND/MN. High-level diffluent flow will be noted across much of the Upper Midwest ahead of this feature which will encourage deep convection along the frontal zone from the upper Great Lakes into portions of the Mid MO Valley. Early in the period, remnant MCS activity may be ongoing across southern MN/southeast SD. However, left-over convective debris may also inhibit surface heating, but may enhance an afternoon boundary for potential thunderstorm development. Latest model guidance suggests the front may be multi faceted with some of the stronger boundary-layer heating expected behind the initial wind shift across SD into northern MN - well northwest of high PW air mass. As a result, forecast soundings suggest surface parcels may struggle to reach convective temperature along the leading wind shift, with only modest lapse rates expected. Even so, deep-layer shear will be more than adequate for sustaining organized updrafts where frontal convergence aids convective development. Higher confidence in robust convection is expected across portions of CO into southeast WY. Strong surface heating should aid thunderstorm development across the higher terrain, along the northern periphery of the Four Corners upper high. This activity should propagate southeast toward lower elevations where it will encounter favorably moist, but weak upslope flow. Hail and wind are possible with this activity. ...Arizona... Upper high is forecast to shift slowly west across southern UT during the day1 period. This will ensure modest easterly 500mb flow across the southern half of AZ. Strong boundary-layer heating will once again prove instrumental in convective development over the higher terrain. This activity will spread toward the lower deserts during the evening with an attendant risk for at least locally severe wind gusts. ..Darrow/Weinman.. 08/22/2025 Read more

MD 2000 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF EASTERN SOUTH DAKOTA AND SOUTHWESTERN MINNESOTA
Mesoscale Discussion 2000 NWS Storm Prediction Center Norman OK 0824 PM CDT Thu Aug 21 2025 Areas affected...Parts of eastern South Dakota and southwestern Minnesota Concerning...Severe potential...Watch unlikely Valid 220124Z - 220300Z Probability of Watch Issuance...20 percent SUMMARY...Locally damaging wind gusts are possible with a southward-moving cluster of storms. DISCUSSION...Earlier semi-discrete thunderstorms have evolved upscale into a small cluster of storms, with an embedded supercell still evident. These storms are tracking southward along the eastern periphery of moderate-strong surface-based buoyancy (per modified 00Z ABR sounding). The consolidated/organized cold pool and robust updrafts (including the embedded supercell) will continue to pose a risk of locally damaging wind gusts with southward extent. However, gradually increasing nocturnal stability in the boundary layer and gust-front parallel deep-layer flow/shear should tend to limit the potential for forward propagation and the overall coverage of severe-wind. ..Weinman/Mosier.. 08/22/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MPX...FSD...ABR... LAT...LON 44249577 43979613 43969682 44139739 44599760 45059749 45379716 45509650 45439606 45169559 44699557 44249577 MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 PM CDT Thu Aug 21 2025 Valid 220100Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN PLAINS... ...SUMMARY... Scattered severe thunderstorms remain possible across portions of the northern Plains and Upper Midwest tonight, with severe wind gusts and large hail the primary concerns. A few strong to severe storms may also occur across parts of southern Arizona this evening. ...01z Update... Upper ridge has flattened considerably across the northern Plains in response to SK short-wave trough. Mid-level flow will gradually veer across the Dakotas as a strong 500mb speed max translates through the base of the trough along the international border late tonight. As this occurs, surface front currently draped from northwest MN-central SD will gradually sag southeast. Thunderstorm coverage along the boundary remains isolated, and this may continue much of the evening until a secondary short wave approaches later tonight. While a meaningful LLJ is not expected ahead of this feature, latest model guidance continues to suggest a weak disturbance will eject across northeast WY/Black Hills region. Elevated convection could markedly increase after 06z across much of SD along/north of the front. Earlier thoughts regarding severe continue, but have lowered severe probabilities across northern MN to reflect less storm coverage along this portion of the boundary. AZ: Upper ridge is holding across the Four Corners region and favorable easterly flow is guiding terrain-induced convection toward the lower deserts. Scattered robust convection is expected to spread toward the more populated ares of the PHX metro over the next few hours. Gusty winds are the primary concern. ..Darrow.. 08/22/2025 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 PM CDT Thu Aug 21 2025 Valid 220100Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN PLAINS... ...SUMMARY... Scattered severe thunderstorms remain possible across portions of the northern Plains and Upper Midwest tonight, with severe wind gusts and large hail the primary concerns. A few strong to severe storms may also occur across parts of southern Arizona this evening. ...01z Update... Upper ridge has flattened considerably across the northern Plains in response to SK short-wave trough. Mid-level flow will gradually veer across the Dakotas as a strong 500mb speed max translates through the base of the trough along the international border late tonight. As this occurs, surface front currently draped from northwest MN-central SD will gradually sag southeast. Thunderstorm coverage along the boundary remains isolated, and this may continue much of the evening until a secondary short wave approaches later tonight. While a meaningful LLJ is not expected ahead of this feature, latest model guidance continues to suggest a weak disturbance will eject across northeast WY/Black Hills region. Elevated convection could markedly increase after 06z across much of SD along/north of the front. Earlier thoughts regarding severe continue, but have lowered severe probabilities across northern MN to reflect less storm coverage along this portion of the boundary. AZ: Upper ridge is holding across the Four Corners region and favorable easterly flow is guiding terrain-induced convection toward the lower deserts. Scattered robust convection is expected to spread toward the more populated ares of the PHX metro over the next few hours. Gusty winds are the primary concern. ..Darrow.. 08/22/2025 Read more