Severe Storms

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1240 AM CDT Thu Aug 21 2025 Valid 211200Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN PLAINS INTO MINNESOTA... ...SUMMARY... Isolated severe thunderstorms are possible across portions of the northern Plains into Minnesota later this afternoon and evening. Severe gusts and hail are the primary concern. ...Northern Plains/Minnesota... Northern Plains upper ridge will flatten considerably during the day1 period as heights fall ahead of a digging upper trough. Early this morning, water-vapor imagery depicts the short wave along the BC/AB border. This feature is forecast to advance into eastern SK by 22/00z before it advances to the SK/MB border by the end of the period. While the primary large-scale forcing will be noted north of the international border, high-level diffluent flow will be noted across the eastern Dakotas/Minnesota - coincident with the front that will be draped across this region at peak heating. Latest model guidance suggests a plume of steep low-level lapse rates will extend across the central Plains into south central SD where surface temperatures are expected to soar through the mid 90s. The majority of CAM guidance struggles to develop more than isolated convection along the surface front - possibly due to the aforementioned weak large-scale ascent. In addition, LLJ does not strengthen appreciably ahead of the boundary, and this also supports isolated coverage. Notably, during the overnight hours, robust convection may develop within a weak warm advection zone across eastern SD into southwest MN - possibly in response to a bit more forcing along the southern fringe of the digging upper trough after 06z. Wind/hail will be the primary threats with both the late-afternoon and overnight convection. Isolated storm coverage favors MRGL Risk at this time. Upstream, surface front will trail across the southern Black Hills into central WY by peak heating. Northeast upslope flow should encourage convection to develop across the higher terrain by late afternoon. While forecast buoyancy is not expected to be particularly strong, adequate deep-layer shear will prove supportive of organized updrafts that could generate hail/wind. ..Darrow/Lyons.. 08/21/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1240 AM CDT Thu Aug 21 2025 Valid 211200Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN PLAINS INTO MINNESOTA... ...SUMMARY... Isolated severe thunderstorms are possible across portions of the northern Plains into Minnesota later this afternoon and evening. Severe gusts and hail are the primary concern. ...Northern Plains/Minnesota... Northern Plains upper ridge will flatten considerably during the day1 period as heights fall ahead of a digging upper trough. Early this morning, water-vapor imagery depicts the short wave along the BC/AB border. This feature is forecast to advance into eastern SK by 22/00z before it advances to the SK/MB border by the end of the period. While the primary large-scale forcing will be noted north of the international border, high-level diffluent flow will be noted across the eastern Dakotas/Minnesota - coincident with the front that will be draped across this region at peak heating. Latest model guidance suggests a plume of steep low-level lapse rates will extend across the central Plains into south central SD where surface temperatures are expected to soar through the mid 90s. The majority of CAM guidance struggles to develop more than isolated convection along the surface front - possibly due to the aforementioned weak large-scale ascent. In addition, LLJ does not strengthen appreciably ahead of the boundary, and this also supports isolated coverage. Notably, during the overnight hours, robust convection may develop within a weak warm advection zone across eastern SD into southwest MN - possibly in response to a bit more forcing along the southern fringe of the digging upper trough after 06z. Wind/hail will be the primary threats with both the late-afternoon and overnight convection. Isolated storm coverage favors MRGL Risk at this time. Upstream, surface front will trail across the southern Black Hills into central WY by peak heating. Northeast upslope flow should encourage convection to develop across the higher terrain by late afternoon. While forecast buoyancy is not expected to be particularly strong, adequate deep-layer shear will prove supportive of organized updrafts that could generate hail/wind. ..Darrow/Lyons.. 08/21/2025 Read more

MD 1997 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF NORTH-CENTRAL INTO NORTHEASTERN MONTANA
Mesoscale Discussion 1997 NWS Storm Prediction Center Norman OK 0702 PM CDT Wed Aug 20 2025 Areas affected...portions of north-central into northeastern Montana Concerning...Severe potential...Watch unlikely Valid 210002Z - 210230Z Probability of Watch Issuance...20 percent SUMMARY...Isolated supercells should persist across portions of north-central into northeastern Montana over the next few hours, accompanied by a severe hail and wind threat. DISCUSSION...Two dominant, discrete supercells have materialized over the past few hours, with severe gusts reported and MRMS mosaic MESH data suggesting hail over 1.5 inches in diameter occurring. These storms are rapidly progressing eastward amid strong mid- to upper-level flow associated with a 300 mb jet streak. 40 kts of effective bulk shear is present, and is coinciding with 1000-1500 J/kg MLCAPE, driven mainly by 8.5+ C/km mid-level lapse rates. Given this environment, supercells should continue eastward for at least a few more hours, with severe gusts potentially reaching 75 mph, along with 1.5+ inch diameter hail. Despite the severe conditions associated with these storms, the severe threat should remain isolated and localized, given the low coverage of storms. As such, a WW issuance is not currently anticipated. ..Squitieri/Mosier.. 08/21/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GGW...TFX... LAT...LON 47150948 47330982 47670998 48460990 48840937 48960660 48640613 48210595 47650610 47230650 47070722 47080819 47090889 47150948 MOST PROBABLE PEAK WIND GUST...65-80 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 0739 PM CDT Wed Aug 20 2025 Valid 210100Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF CENTRAL MONTANA INTO NORTHERN NORTH DAKOTA AND ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY... ...SUMMARY... Isolated severe thunderstorms are possible from central Montana into northern North Dakota tonight. A few wind gusts may also be noted with storms over the lower Mississippi Valley early this evening. ...01z Update... Early-evening water-vapor imagery depicts an upper trough extending across southeast BC into the northern Rockies. This feature is forecast to advance to near the AB/SK border by the end of the period, with modest mid-level height falls expected across northeast MT into ND. As 500mb speed max strengthens over southern SK later tonight some increase in LLJ should be noted across western ND - just ahead of the progressive surface front. Isolated robust convection has developed ahead of the short wave from southwest SK into central MT. This activity may continue to generate gusty winds and hail, but new updrafts are expected downstream across western ND with time. Vis imagery suggests high-based updrafts are deepening across southeast MT into southwest ND, and isolated severe may ultimately evolve along the northern edge of this steep lapse rate plume, immediately ahead of the front. Boundary-layer heating was instrumental in scattered-widespread convection across the northern Gulf States this afternoon. While considerable convective overturning has occurred, a pocket of modest instability persists across much of LA. Cluster of strong-locally severe thunderstorms will drift south across this region over the next several hours. Boundary-layer cooling will negate updraft intensity by mid evening. ..Darrow.. 08/21/2025 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0739 PM CDT Wed Aug 20 2025 Valid 210100Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF CENTRAL MONTANA INTO NORTHERN NORTH DAKOTA AND ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY... ...SUMMARY... Isolated severe thunderstorms are possible from central Montana into northern North Dakota tonight. A few wind gusts may also be noted with storms over the lower Mississippi Valley early this evening. ...01z Update... Early-evening water-vapor imagery depicts an upper trough extending across southeast BC into the northern Rockies. This feature is forecast to advance to near the AB/SK border by the end of the period, with modest mid-level height falls expected across northeast MT into ND. As 500mb speed max strengthens over southern SK later tonight some increase in LLJ should be noted across western ND - just ahead of the progressive surface front. Isolated robust convection has developed ahead of the short wave from southwest SK into central MT. This activity may continue to generate gusty winds and hail, but new updrafts are expected downstream across western ND with time. Vis imagery suggests high-based updrafts are deepening across southeast MT into southwest ND, and isolated severe may ultimately evolve along the northern edge of this steep lapse rate plume, immediately ahead of the front. Boundary-layer heating was instrumental in scattered-widespread convection across the northern Gulf States this afternoon. While considerable convective overturning has occurred, a pocket of modest instability persists across much of LA. Cluster of strong-locally severe thunderstorms will drift south across this region over the next several hours. Boundary-layer cooling will negate updraft intensity by mid evening. ..Darrow.. 08/21/2025 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0739 PM CDT Wed Aug 20 2025 Valid 210100Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF CENTRAL MONTANA INTO NORTHERN NORTH DAKOTA AND ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY... ...SUMMARY... Isolated severe thunderstorms are possible from central Montana into northern North Dakota tonight. A few wind gusts may also be noted with storms over the lower Mississippi Valley early this evening. ...01z Update... Early-evening water-vapor imagery depicts an upper trough extending across southeast BC into the northern Rockies. This feature is forecast to advance to near the AB/SK border by the end of the period, with modest mid-level height falls expected across northeast MT into ND. As 500mb speed max strengthens over southern SK later tonight some increase in LLJ should be noted across western ND - just ahead of the progressive surface front. Isolated robust convection has developed ahead of the short wave from southwest SK into central MT. This activity may continue to generate gusty winds and hail, but new updrafts are expected downstream across western ND with time. Vis imagery suggests high-based updrafts are deepening across southeast MT into southwest ND, and isolated severe may ultimately evolve along the northern edge of this steep lapse rate plume, immediately ahead of the front. Boundary-layer heating was instrumental in scattered-widespread convection across the northern Gulf States this afternoon. While considerable convective overturning has occurred, a pocket of modest instability persists across much of LA. Cluster of strong-locally severe thunderstorms will drift south across this region over the next several hours. Boundary-layer cooling will negate updraft intensity by mid evening. ..Darrow.. 08/21/2025 Read more

No watches are valid as of Wed Aug 20 23:03:02 UTC 2025.

No Mesoscale Discussions are in effect as of Wed Aug 20 23:03:02 UTC 2025.

MD 1996 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR NORTHWESTERN MONTANA
Mesoscale Discussion 1996 NWS Storm Prediction Center Norman OK 0349 PM CDT Wed Aug 20 2025 Areas affected...Northwestern Montana Concerning...Severe potential...Watch unlikely Valid 202049Z - 202245Z Probability of Watch Issuance...20 percent SUMMARY...A couple of supercells may produce severe wind gusts and large hail this afternoon and evening. A watch is not currently expected, but convective trends will need to be monitored. DISCUSSION...With upper 40s to low 50s dewpoints against the northern Rockies, convection has been deepening in north-central Montana as a shortwave trough moves into the region. Radar imagery from KTFX shows intensifying storms northwest of Great Falls. With 35-45 kts of effective shear, long hodographs, and 500-1000 J/kg MLCAPE, a couple of supercells may eventually evolve from this convection. Severe wind gusts will likely be the primary threat, but large hail will also be possible with the most organized supercells. The exact timing of greater storm coverage and intensity will depend on when MLCIN erodes away from the terrain. A watch is not currently expected, but convective trends will need to monitored this afternoon. ..Wendt/Gleason.. 08/20/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TFX... LAT...LON 47231205 47711250 48611241 49181144 49170994 48980942 48470922 47001002 46511143 47231205 MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0429 PM CDT Wed Aug 20 2025 Valid 221200Z - 281200Z An upper-level ridge oriented southeast-northwest will amplify over the West into the weekend, with monsoonal moisture moving into California, the Great Basin, and portions of the Northwest and Rocky Mountain Areas. Well above normal temperatures are expected for much of the West, especially ahead and away from the cloud cover and wet thunderstorms associated with the monsoonal surge. The ridge is likely to weaken late in the weekend and early next with the upper high forecast to shift from west of the Four Corners to southern New Mexico and southwest Texas. The magnitude and duration of the monsoonal moisture across the West Coast and central Intermountain West remains uncertain beyond this weekend, especially with the uncertainty of the upper-level pattern over the West Coast and northern Intermountain West early to mid next week. ...Day 3/Friday... Isolated to scattered mixed wet/dry thunderstorms are likely from the West Slope across the southern/central Great Basin onto the eastern slopes of the southern/central Sierra on Day 3/Friday. Two 10% areas were introduced in areas where drier thunderstorms are most likely to overlap receptive fuels. Wetter storms are more likely across Utah into western Colorado, which precluded expanding the 10% areas at this time. However, it is expected these areas will be refined in the next 48 hours as more high-resolution forecast guidance becomes available. Isolated thunderstorms are likely in portions of southern California along eastern/northern slopes of the Peninsular Ranges, over the Mojave, and possibly into the Transverse Ranges. Wetter storms are likely as PWAT values are over 1" and dewpoints increase into the 40s and possibly low 50s, but cloud bases are likely to be over 3-km with a hot/dry sub-cloud layer. Isolated high-based showers and thunderstorms are also possible overnight over the Coast Ranges of southern California. For the West, hot/dry/unstable/locally breezy conditions are likely away from the deeper monsoonal moisture, especially with the West Coast thermal trough establishing from southern California through western Washington. Dry and breezy conditions are likely in portions of New England as Hurricane Erin passes offshore. Breezy northerly winds amid RH below 40% are likely which may result in elevated conditions, especially in Maine where the driest fuels appear to be. ...Day 4/Saturday - Day 6/Monday... Isolated drier thunderstorms are likely in northeast California, northwest/northeast Nevada, and south-central Oregon on Day 4/Saturday. Thunderstorms chances expand northward farther into Oregon and possibly into Washington on Day 5/Sunday - Day 6/Monday. These storms are likely to be a mix of wet/dry, but too much forecast uncertainty exists to include probabilities beyond Day 4/Saturday at this time. Farther south, wetter thunderstorms are expected across the Great Basin into Colorado. However, how far north the deeper monsoonal moisture extends remains uncertainty with possibly I-80 or Highway 50 serving as potential dividing lines. Hot, dry, and unstable conditions will continue ahead/along the leading edge of the monsoonal moisture across the West. The thermal trough will continue to be a focus point for these conditions through the weekend. ..Nauslar.. 08/20/2025 ...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 0429 PM CDT Wed Aug 20 2025 Valid 221200Z - 281200Z An upper-level ridge oriented southeast-northwest will amplify over the West into the weekend, with monsoonal moisture moving into California, the Great Basin, and portions of the Northwest and Rocky Mountain Areas. Well above normal temperatures are expected for much of the West, especially ahead and away from the cloud cover and wet thunderstorms associated with the monsoonal surge. The ridge is likely to weaken late in the weekend and early next with the upper high forecast to shift from west of the Four Corners to southern New Mexico and southwest Texas. The magnitude and duration of the monsoonal moisture across the West Coast and central Intermountain West remains uncertain beyond this weekend, especially with the uncertainty of the upper-level pattern over the West Coast and northern Intermountain West early to mid next week. ...Day 3/Friday... Isolated to scattered mixed wet/dry thunderstorms are likely from the West Slope across the southern/central Great Basin onto the eastern slopes of the southern/central Sierra on Day 3/Friday. Two 10% areas were introduced in areas where drier thunderstorms are most likely to overlap receptive fuels. Wetter storms are more likely across Utah into western Colorado, which precluded expanding the 10% areas at this time. However, it is expected these areas will be refined in the next 48 hours as more high-resolution forecast guidance becomes available. Isolated thunderstorms are likely in portions of southern California along eastern/northern slopes of the Peninsular Ranges, over the Mojave, and possibly into the Transverse Ranges. Wetter storms are likely as PWAT values are over 1" and dewpoints increase into the 40s and possibly low 50s, but cloud bases are likely to be over 3-km with a hot/dry sub-cloud layer. Isolated high-based showers and thunderstorms are also possible overnight over the Coast Ranges of southern California. For the West, hot/dry/unstable/locally breezy conditions are likely away from the deeper monsoonal moisture, especially with the West Coast thermal trough establishing from southern California through western Washington. Dry and breezy conditions are likely in portions of New England as Hurricane Erin passes offshore. Breezy northerly winds amid RH below 40% are likely which may result in elevated conditions, especially in Maine where the driest fuels appear to be. ...Day 4/Saturday - Day 6/Monday... Isolated drier thunderstorms are likely in northeast California, northwest/northeast Nevada, and south-central Oregon on Day 4/Saturday. Thunderstorms chances expand northward farther into Oregon and possibly into Washington on Day 5/Sunday - Day 6/Monday. These storms are likely to be a mix of wet/dry, but too much forecast uncertainty exists to include probabilities beyond Day 4/Saturday at this time. Farther south, wetter thunderstorms are expected across the Great Basin into Colorado. However, how far north the deeper monsoonal moisture extends remains uncertainty with possibly I-80 or Highway 50 serving as potential dividing lines. Hot, dry, and unstable conditions will continue ahead/along the leading edge of the monsoonal moisture across the West. The thermal trough will continue to be a focus point for these conditions through the weekend. ..Nauslar.. 08/20/2025 ...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 0429 PM CDT Wed Aug 20 2025 Valid 221200Z - 281200Z An upper-level ridge oriented southeast-northwest will amplify over the West into the weekend, with monsoonal moisture moving into California, the Great Basin, and portions of the Northwest and Rocky Mountain Areas. Well above normal temperatures are expected for much of the West, especially ahead and away from the cloud cover and wet thunderstorms associated with the monsoonal surge. The ridge is likely to weaken late in the weekend and early next with the upper high forecast to shift from west of the Four Corners to southern New Mexico and southwest Texas. The magnitude and duration of the monsoonal moisture across the West Coast and central Intermountain West remains uncertain beyond this weekend, especially with the uncertainty of the upper-level pattern over the West Coast and northern Intermountain West early to mid next week. ...Day 3/Friday... Isolated to scattered mixed wet/dry thunderstorms are likely from the West Slope across the southern/central Great Basin onto the eastern slopes of the southern/central Sierra on Day 3/Friday. Two 10% areas were introduced in areas where drier thunderstorms are most likely to overlap receptive fuels. Wetter storms are more likely across Utah into western Colorado, which precluded expanding the 10% areas at this time. However, it is expected these areas will be refined in the next 48 hours as more high-resolution forecast guidance becomes available. Isolated thunderstorms are likely in portions of southern California along eastern/northern slopes of the Peninsular Ranges, over the Mojave, and possibly into the Transverse Ranges. Wetter storms are likely as PWAT values are over 1" and dewpoints increase into the 40s and possibly low 50s, but cloud bases are likely to be over 3-km with a hot/dry sub-cloud layer. Isolated high-based showers and thunderstorms are also possible overnight over the Coast Ranges of southern California. For the West, hot/dry/unstable/locally breezy conditions are likely away from the deeper monsoonal moisture, especially with the West Coast thermal trough establishing from southern California through western Washington. Dry and breezy conditions are likely in portions of New England as Hurricane Erin passes offshore. Breezy northerly winds amid RH below 40% are likely which may result in elevated conditions, especially in Maine where the driest fuels appear to be. ...Day 4/Saturday - Day 6/Monday... Isolated drier thunderstorms are likely in northeast California, northwest/northeast Nevada, and south-central Oregon on Day 4/Saturday. Thunderstorms chances expand northward farther into Oregon and possibly into Washington on Day 5/Sunday - Day 6/Monday. These storms are likely to be a mix of wet/dry, but too much forecast uncertainty exists to include probabilities beyond Day 4/Saturday at this time. Farther south, wetter thunderstorms are expected across the Great Basin into Colorado. However, how far north the deeper monsoonal moisture extends remains uncertainty with possibly I-80 or Highway 50 serving as potential dividing lines. Hot, dry, and unstable conditions will continue ahead/along the leading edge of the monsoonal moisture across the West. The thermal trough will continue to be a focus point for these conditions through the weekend. ..Nauslar.. 08/20/2025 ...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 0429 PM CDT Wed Aug 20 2025 Valid 221200Z - 281200Z An upper-level ridge oriented southeast-northwest will amplify over the West into the weekend, with monsoonal moisture moving into California, the Great Basin, and portions of the Northwest and Rocky Mountain Areas. Well above normal temperatures are expected for much of the West, especially ahead and away from the cloud cover and wet thunderstorms associated with the monsoonal surge. The ridge is likely to weaken late in the weekend and early next with the upper high forecast to shift from west of the Four Corners to southern New Mexico and southwest Texas. The magnitude and duration of the monsoonal moisture across the West Coast and central Intermountain West remains uncertain beyond this weekend, especially with the uncertainty of the upper-level pattern over the West Coast and northern Intermountain West early to mid next week. ...Day 3/Friday... Isolated to scattered mixed wet/dry thunderstorms are likely from the West Slope across the southern/central Great Basin onto the eastern slopes of the southern/central Sierra on Day 3/Friday. Two 10% areas were introduced in areas where drier thunderstorms are most likely to overlap receptive fuels. Wetter storms are more likely across Utah into western Colorado, which precluded expanding the 10% areas at this time. However, it is expected these areas will be refined in the next 48 hours as more high-resolution forecast guidance becomes available. Isolated thunderstorms are likely in portions of southern California along eastern/northern slopes of the Peninsular Ranges, over the Mojave, and possibly into the Transverse Ranges. Wetter storms are likely as PWAT values are over 1" and dewpoints increase into the 40s and possibly low 50s, but cloud bases are likely to be over 3-km with a hot/dry sub-cloud layer. Isolated high-based showers and thunderstorms are also possible overnight over the Coast Ranges of southern California. For the West, hot/dry/unstable/locally breezy conditions are likely away from the deeper monsoonal moisture, especially with the West Coast thermal trough establishing from southern California through western Washington. Dry and breezy conditions are likely in portions of New England as Hurricane Erin passes offshore. Breezy northerly winds amid RH below 40% are likely which may result in elevated conditions, especially in Maine where the driest fuels appear to be. ...Day 4/Saturday - Day 6/Monday... Isolated drier thunderstorms are likely in northeast California, northwest/northeast Nevada, and south-central Oregon on Day 4/Saturday. Thunderstorms chances expand northward farther into Oregon and possibly into Washington on Day 5/Sunday - Day 6/Monday. These storms are likely to be a mix of wet/dry, but too much forecast uncertainty exists to include probabilities beyond Day 4/Saturday at this time. Farther south, wetter thunderstorms are expected across the Great Basin into Colorado. However, how far north the deeper monsoonal moisture extends remains uncertainty with possibly I-80 or Highway 50 serving as potential dividing lines. Hot, dry, and unstable conditions will continue ahead/along the leading edge of the monsoonal moisture across the West. The thermal trough will continue to be a focus point for these conditions through the weekend. ..Nauslar.. 08/20/2025 ...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 0429 PM CDT Wed Aug 20 2025 Valid 221200Z - 281200Z An upper-level ridge oriented southeast-northwest will amplify over the West into the weekend, with monsoonal moisture moving into California, the Great Basin, and portions of the Northwest and Rocky Mountain Areas. Well above normal temperatures are expected for much of the West, especially ahead and away from the cloud cover and wet thunderstorms associated with the monsoonal surge. The ridge is likely to weaken late in the weekend and early next with the upper high forecast to shift from west of the Four Corners to southern New Mexico and southwest Texas. The magnitude and duration of the monsoonal moisture across the West Coast and central Intermountain West remains uncertain beyond this weekend, especially with the uncertainty of the upper-level pattern over the West Coast and northern Intermountain West early to mid next week. ...Day 3/Friday... Isolated to scattered mixed wet/dry thunderstorms are likely from the West Slope across the southern/central Great Basin onto the eastern slopes of the southern/central Sierra on Day 3/Friday. Two 10% areas were introduced in areas where drier thunderstorms are most likely to overlap receptive fuels. Wetter storms are more likely across Utah into western Colorado, which precluded expanding the 10% areas at this time. However, it is expected these areas will be refined in the next 48 hours as more high-resolution forecast guidance becomes available. Isolated thunderstorms are likely in portions of southern California along eastern/northern slopes of the Peninsular Ranges, over the Mojave, and possibly into the Transverse Ranges. Wetter storms are likely as PWAT values are over 1" and dewpoints increase into the 40s and possibly low 50s, but cloud bases are likely to be over 3-km with a hot/dry sub-cloud layer. Isolated high-based showers and thunderstorms are also possible overnight over the Coast Ranges of southern California. For the West, hot/dry/unstable/locally breezy conditions are likely away from the deeper monsoonal moisture, especially with the West Coast thermal trough establishing from southern California through western Washington. Dry and breezy conditions are likely in portions of New England as Hurricane Erin passes offshore. Breezy northerly winds amid RH below 40% are likely which may result in elevated conditions, especially in Maine where the driest fuels appear to be. ...Day 4/Saturday - Day 6/Monday... Isolated drier thunderstorms are likely in northeast California, northwest/northeast Nevada, and south-central Oregon on Day 4/Saturday. Thunderstorms chances expand northward farther into Oregon and possibly into Washington on Day 5/Sunday - Day 6/Monday. These storms are likely to be a mix of wet/dry, but too much forecast uncertainty exists to include probabilities beyond Day 4/Saturday at this time. Farther south, wetter thunderstorms are expected across the Great Basin into Colorado. However, how far north the deeper monsoonal moisture extends remains uncertainty with possibly I-80 or Highway 50 serving as potential dividing lines. Hot, dry, and unstable conditions will continue ahead/along the leading edge of the monsoonal moisture across the West. The thermal trough will continue to be a focus point for these conditions through the weekend. ..Nauslar.. 08/20/2025 ...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 0429 PM CDT Wed Aug 20 2025 Valid 221200Z - 281200Z An upper-level ridge oriented southeast-northwest will amplify over the West into the weekend, with monsoonal moisture moving into California, the Great Basin, and portions of the Northwest and Rocky Mountain Areas. Well above normal temperatures are expected for much of the West, especially ahead and away from the cloud cover and wet thunderstorms associated with the monsoonal surge. The ridge is likely to weaken late in the weekend and early next with the upper high forecast to shift from west of the Four Corners to southern New Mexico and southwest Texas. The magnitude and duration of the monsoonal moisture across the West Coast and central Intermountain West remains uncertain beyond this weekend, especially with the uncertainty of the upper-level pattern over the West Coast and northern Intermountain West early to mid next week. ...Day 3/Friday... Isolated to scattered mixed wet/dry thunderstorms are likely from the West Slope across the southern/central Great Basin onto the eastern slopes of the southern/central Sierra on Day 3/Friday. Two 10% areas were introduced in areas where drier thunderstorms are most likely to overlap receptive fuels. Wetter storms are more likely across Utah into western Colorado, which precluded expanding the 10% areas at this time. However, it is expected these areas will be refined in the next 48 hours as more high-resolution forecast guidance becomes available. Isolated thunderstorms are likely in portions of southern California along eastern/northern slopes of the Peninsular Ranges, over the Mojave, and possibly into the Transverse Ranges. Wetter storms are likely as PWAT values are over 1" and dewpoints increase into the 40s and possibly low 50s, but cloud bases are likely to be over 3-km with a hot/dry sub-cloud layer. Isolated high-based showers and thunderstorms are also possible overnight over the Coast Ranges of southern California. For the West, hot/dry/unstable/locally breezy conditions are likely away from the deeper monsoonal moisture, especially with the West Coast thermal trough establishing from southern California through western Washington. Dry and breezy conditions are likely in portions of New England as Hurricane Erin passes offshore. Breezy northerly winds amid RH below 40% are likely which may result in elevated conditions, especially in Maine where the driest fuels appear to be. ...Day 4/Saturday - Day 6/Monday... Isolated drier thunderstorms are likely in northeast California, northwest/northeast Nevada, and south-central Oregon on Day 4/Saturday. Thunderstorms chances expand northward farther into Oregon and possibly into Washington on Day 5/Sunday - Day 6/Monday. These storms are likely to be a mix of wet/dry, but too much forecast uncertainty exists to include probabilities beyond Day 4/Saturday at this time. Farther south, wetter thunderstorms are expected across the Great Basin into Colorado. However, how far north the deeper monsoonal moisture extends remains uncertainty with possibly I-80 or Highway 50 serving as potential dividing lines. Hot, dry, and unstable conditions will continue ahead/along the leading edge of the monsoonal moisture across the West. The thermal trough will continue to be a focus point for these conditions through the weekend. ..Nauslar.. 08/20/2025 ...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 0429 PM CDT Wed Aug 20 2025 Valid 221200Z - 281200Z An upper-level ridge oriented southeast-northwest will amplify over the West into the weekend, with monsoonal moisture moving into California, the Great Basin, and portions of the Northwest and Rocky Mountain Areas. Well above normal temperatures are expected for much of the West, especially ahead and away from the cloud cover and wet thunderstorms associated with the monsoonal surge. The ridge is likely to weaken late in the weekend and early next with the upper high forecast to shift from west of the Four Corners to southern New Mexico and southwest Texas. The magnitude and duration of the monsoonal moisture across the West Coast and central Intermountain West remains uncertain beyond this weekend, especially with the uncertainty of the upper-level pattern over the West Coast and northern Intermountain West early to mid next week. ...Day 3/Friday... Isolated to scattered mixed wet/dry thunderstorms are likely from the West Slope across the southern/central Great Basin onto the eastern slopes of the southern/central Sierra on Day 3/Friday. Two 10% areas were introduced in areas where drier thunderstorms are most likely to overlap receptive fuels. Wetter storms are more likely across Utah into western Colorado, which precluded expanding the 10% areas at this time. However, it is expected these areas will be refined in the next 48 hours as more high-resolution forecast guidance becomes available. Isolated thunderstorms are likely in portions of southern California along eastern/northern slopes of the Peninsular Ranges, over the Mojave, and possibly into the Transverse Ranges. Wetter storms are likely as PWAT values are over 1" and dewpoints increase into the 40s and possibly low 50s, but cloud bases are likely to be over 3-km with a hot/dry sub-cloud layer. Isolated high-based showers and thunderstorms are also possible overnight over the Coast Ranges of southern California. For the West, hot/dry/unstable/locally breezy conditions are likely away from the deeper monsoonal moisture, especially with the West Coast thermal trough establishing from southern California through western Washington. Dry and breezy conditions are likely in portions of New England as Hurricane Erin passes offshore. Breezy northerly winds amid RH below 40% are likely which may result in elevated conditions, especially in Maine where the driest fuels appear to be. ...Day 4/Saturday - Day 6/Monday... Isolated drier thunderstorms are likely in northeast California, northwest/northeast Nevada, and south-central Oregon on Day 4/Saturday. Thunderstorms chances expand northward farther into Oregon and possibly into Washington on Day 5/Sunday - Day 6/Monday. These storms are likely to be a mix of wet/dry, but too much forecast uncertainty exists to include probabilities beyond Day 4/Saturday at this time. Farther south, wetter thunderstorms are expected across the Great Basin into Colorado. However, how far north the deeper monsoonal moisture extends remains uncertainty with possibly I-80 or Highway 50 serving as potential dividing lines. Hot, dry, and unstable conditions will continue ahead/along the leading edge of the monsoonal moisture across the West. The thermal trough will continue to be a focus point for these conditions through the weekend. ..Nauslar.. 08/20/2025 ...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 0429 PM CDT Wed Aug 20 2025 Valid 221200Z - 281200Z An upper-level ridge oriented southeast-northwest will amplify over the West into the weekend, with monsoonal moisture moving into California, the Great Basin, and portions of the Northwest and Rocky Mountain Areas. Well above normal temperatures are expected for much of the West, especially ahead and away from the cloud cover and wet thunderstorms associated with the monsoonal surge. The ridge is likely to weaken late in the weekend and early next with the upper high forecast to shift from west of the Four Corners to southern New Mexico and southwest Texas. The magnitude and duration of the monsoonal moisture across the West Coast and central Intermountain West remains uncertain beyond this weekend, especially with the uncertainty of the upper-level pattern over the West Coast and northern Intermountain West early to mid next week. ...Day 3/Friday... Isolated to scattered mixed wet/dry thunderstorms are likely from the West Slope across the southern/central Great Basin onto the eastern slopes of the southern/central Sierra on Day 3/Friday. Two 10% areas were introduced in areas where drier thunderstorms are most likely to overlap receptive fuels. Wetter storms are more likely across Utah into western Colorado, which precluded expanding the 10% areas at this time. However, it is expected these areas will be refined in the next 48 hours as more high-resolution forecast guidance becomes available. Isolated thunderstorms are likely in portions of southern California along eastern/northern slopes of the Peninsular Ranges, over the Mojave, and possibly into the Transverse Ranges. Wetter storms are likely as PWAT values are over 1" and dewpoints increase into the 40s and possibly low 50s, but cloud bases are likely to be over 3-km with a hot/dry sub-cloud layer. Isolated high-based showers and thunderstorms are also possible overnight over the Coast Ranges of southern California. For the West, hot/dry/unstable/locally breezy conditions are likely away from the deeper monsoonal moisture, especially with the West Coast thermal trough establishing from southern California through western Washington. Dry and breezy conditions are likely in portions of New England as Hurricane Erin passes offshore. Breezy northerly winds amid RH below 40% are likely which may result in elevated conditions, especially in Maine where the driest fuels appear to be. ...Day 4/Saturday - Day 6/Monday... Isolated drier thunderstorms are likely in northeast California, northwest/northeast Nevada, and south-central Oregon on Day 4/Saturday. Thunderstorms chances expand northward farther into Oregon and possibly into Washington on Day 5/Sunday - Day 6/Monday. These storms are likely to be a mix of wet/dry, but too much forecast uncertainty exists to include probabilities beyond Day 4/Saturday at this time. Farther south, wetter thunderstorms are expected across the Great Basin into Colorado. However, how far north the deeper monsoonal moisture extends remains uncertainty with possibly I-80 or Highway 50 serving as potential dividing lines. Hot, dry, and unstable conditions will continue ahead/along the leading edge of the monsoonal moisture across the West. The thermal trough will continue to be a focus point for these conditions through the weekend. ..Nauslar.. 08/20/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 1995 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR NORTHEAST ALABAMA...NORTHWEST GEORGIA...AND PORTIONS OF SOUTHEAST TENNESSEE
Mesoscale Discussion 1995 NWS Storm Prediction Center Norman OK 0250 PM CDT Wed Aug 20 2025 Areas affected...northeast Alabama...northwest Georgia...and portions of southeast Tennessee Concerning...Severe potential...Watch unlikely Valid 201950Z - 202115Z Probability of Watch Issuance...5 percent SUMMARY...Isolated severe wind gusts are possible this afternoon. DISCUSSION...A cluster of storms has developed across southeast Tennessee. As these storms, and associated outflow, move south, they will encounter increasing instability with temperatures in the upper 80s to low 90s and dewpoints in the mid 70s yielding 2500 J/kg MLCAPE. Despite the favorable thermodynamic environment, shear is quite weak (flow less than 20 knots in the entire troposphere on the HTX VWP). This weak shear will likely result in mostly unorganized storms with strong outflow. Stronger cores/water loading will support the threat for microbursts, particularly where boundary collisions occur. Expect the greatest severe threat to shift south through the remainder of the afternoon and into the evening as outflow continues to progress south. ..Bentley/Gleason.. 08/20/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MRX...FFC...OHX...BMX...HUN... LAT...LON 34108738 35258617 35718500 35568432 34848410 34008453 33348479 32868617 33268694 34108738 MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Wed Aug 20 2025 Valid 202000Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF TEXAS INTO THE LOWER MISSISSIPPI VALLEY/SOUTHEAST...AND THE NORTHERN PLAINS... ...SUMMARY... Scattered thunderstorms from Texas across the Lower Mississippi Valley and Southeast may pose a risk for localized damaging wind gusts this afternoon and evening. Isolated severe thunderstorms may also occur across parts of central/eastern Montana and northern North Dakota, mainly this evening and overnight. ...20z Update... Changes were made to clear the Marginal Risk across portions of central Texas where thunderstorms and outflow have moved southward. The Marginal Risk was expanded across the Southeast into portions of northwest Georgia and eastern Alabama. A cluster of thunderstorms continues to sag southward into this region, with cores exhibiting some uptick in intensity. See MCD#1995. Otherwise, the outlook remains on track with no additional changes needed. See previous discussion below for more information. ..Thornton.. 08/20/2025 .PREV DISCUSSION... /ISSUED 1128 AM CDT Wed Aug 20 2025/ ...Texas into the Lower Mississippi Valley and Southeast... A convectively reinforced front/outflow boundary from earlier/ongoing convection should once again provide a focus for renewed convective development this afternoon from parts of west-central TX eastward into the lower MS Valley and Southeast. Mid-level flow and related deep-layer shear are expected to remain weak, which should generally limit thunderstorm organization. Still, a moderately to strongly unstable environment will exist along/south of the front with continued daytime heating, with scattered to numerous thunderstorms likely. Similar to yesterday, wet microbursts from convective downdrafts may produce isolated damaging winds as low-level lapse rates become steepened. These thunderstorms should weaken through the evening with the loss of daytime heating. ...Northern Plains... The northern Plains will be influenced by late-day/overnight mid-level height falls as a shortwave trough moves eastward from the Canadian/northern Rockies, with a related cold front moving across central/eastern MT into ND tonight. A narrow corridor of moderate to strong instability will likely develop along/ahead of the cold front, and near a pre-frontal surface trough. But, warm mid-level temperatures and a capped airmass will likely exist along/south of the international border, which should inhibit robust convective development for much of the day. One exception may be in the post-frontal environment across eastern MT this evening/tonight. The environment here should be conducive to isolated severe thunderstorms capable of producing both large hail and severe gusts. While the risk for severe thunderstorms appears more conditional into ND where stronger destabilization is expected, isolated convective development may still occur across northwestern ND in proximity to the surface low/front late this afternoon, and perhaps more so this evening/overnight. Should this occur, forecast soundings indicate the environment would support isolated supercell development with a related hail/wind threat. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Wed Aug 20 2025 Valid 202000Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF TEXAS INTO THE LOWER MISSISSIPPI VALLEY/SOUTHEAST...AND THE NORTHERN PLAINS... ...SUMMARY... Scattered thunderstorms from Texas across the Lower Mississippi Valley and Southeast may pose a risk for localized damaging wind gusts this afternoon and evening. Isolated severe thunderstorms may also occur across parts of central/eastern Montana and northern North Dakota, mainly this evening and overnight. ...20z Update... Changes were made to clear the Marginal Risk across portions of central Texas where thunderstorms and outflow have moved southward. The Marginal Risk was expanded across the Southeast into portions of northwest Georgia and eastern Alabama. A cluster of thunderstorms continues to sag southward into this region, with cores exhibiting some uptick in intensity. See MCD#1995. Otherwise, the outlook remains on track with no additional changes needed. See previous discussion below for more information. ..Thornton.. 08/20/2025 .PREV DISCUSSION... /ISSUED 1128 AM CDT Wed Aug 20 2025/ ...Texas into the Lower Mississippi Valley and Southeast... A convectively reinforced front/outflow boundary from earlier/ongoing convection should once again provide a focus for renewed convective development this afternoon from parts of west-central TX eastward into the lower MS Valley and Southeast. Mid-level flow and related deep-layer shear are expected to remain weak, which should generally limit thunderstorm organization. Still, a moderately to strongly unstable environment will exist along/south of the front with continued daytime heating, with scattered to numerous thunderstorms likely. Similar to yesterday, wet microbursts from convective downdrafts may produce isolated damaging winds as low-level lapse rates become steepened. These thunderstorms should weaken through the evening with the loss of daytime heating. ...Northern Plains... The northern Plains will be influenced by late-day/overnight mid-level height falls as a shortwave trough moves eastward from the Canadian/northern Rockies, with a related cold front moving across central/eastern MT into ND tonight. A narrow corridor of moderate to strong instability will likely develop along/ahead of the cold front, and near a pre-frontal surface trough. But, warm mid-level temperatures and a capped airmass will likely exist along/south of the international border, which should inhibit robust convective development for much of the day. One exception may be in the post-frontal environment across eastern MT this evening/tonight. The environment here should be conducive to isolated severe thunderstorms capable of producing both large hail and severe gusts. While the risk for severe thunderstorms appears more conditional into ND where stronger destabilization is expected, isolated convective development may still occur across northwestern ND in proximity to the surface low/front late this afternoon, and perhaps more so this evening/overnight. Should this occur, forecast soundings indicate the environment would support isolated supercell development with a related hail/wind threat. Read more