Severe Storms

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0201 AM CDT Mon Aug 18 2025 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Synopsis... As upper-level ridging builds rapidly over the West, modest south-southwest deep layer flow and efficient daytime mixing of a deep/dry boundary layer will support sustained south-southwest winds of 10-12 mph across southern/northern NV this afternoon. Winds combined with relative humidity nearing 10 percent will support short duration and localized elevated fire weather conditions across southern, central and northeastern NV where very dry fuels exist. ...Northern Rockies/Central Idaho Mountains... A mid-level trough will persist over the Northwest on the periphery of the building upper ridge. Residual Pacific/monsoon moisture and daytime heating will result in isolated showers and thunderstorms across northern ID and higher terrain of western MT. Although northeast thunderstorm motions of 25-30 knots will limit rainfall, fuels remain mostly non-receptive to new lightning ignitions across the Northern Rockies, precluding introduction of dry thunderstorm highlights. ..Lyons.. 08/18/2025 ...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 0201 AM CDT Mon Aug 18 2025 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Synopsis... As upper-level ridging builds rapidly over the West, modest south-southwest deep layer flow and efficient daytime mixing of a deep/dry boundary layer will support sustained south-southwest winds of 10-12 mph across southern/northern NV this afternoon. Winds combined with relative humidity nearing 10 percent will support short duration and localized elevated fire weather conditions across southern, central and northeastern NV where very dry fuels exist. ...Northern Rockies/Central Idaho Mountains... A mid-level trough will persist over the Northwest on the periphery of the building upper ridge. Residual Pacific/monsoon moisture and daytime heating will result in isolated showers and thunderstorms across northern ID and higher terrain of western MT. Although northeast thunderstorm motions of 25-30 knots will limit rainfall, fuels remain mostly non-receptive to new lightning ignitions across the Northern Rockies, precluding introduction of dry thunderstorm highlights. ..Lyons.. 08/18/2025 ...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 0201 AM CDT Mon Aug 18 2025 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Synopsis... As upper-level ridging builds rapidly over the West, modest south-southwest deep layer flow and efficient daytime mixing of a deep/dry boundary layer will support sustained south-southwest winds of 10-12 mph across southern/northern NV this afternoon. Winds combined with relative humidity nearing 10 percent will support short duration and localized elevated fire weather conditions across southern, central and northeastern NV where very dry fuels exist. ...Northern Rockies/Central Idaho Mountains... A mid-level trough will persist over the Northwest on the periphery of the building upper ridge. Residual Pacific/monsoon moisture and daytime heating will result in isolated showers and thunderstorms across northern ID and higher terrain of western MT. Although northeast thunderstorm motions of 25-30 knots will limit rainfall, fuels remain mostly non-receptive to new lightning ignitions across the Northern Rockies, precluding introduction of dry thunderstorm highlights. ..Lyons.. 08/18/2025 ...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 1253 AM CDT Mon Aug 18 2025 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A severe threat is not expected across the continental U.S. on Tuesday or Tuesday night. ...DISCUSSION... A mid-level ridge will build northward across the central Rockies and northern High Plains on Tuesday, as a subtle shortwave trough moves through the Great Lakes region. At the surface, a cold front will advance southward into the Ohio and mid Mississippi Valleys, extending westward into the southern Plains. As surface temperatures warm during the day, low-level convergence near the front will be favorable for isolated to scattered thunderstorm development. Limited large-scale ascent and weak deep-layer shear will be unfavorable for severe storms. Further northwest into the north-central states, moderate instability will be possible by Tuesday afternoon, mainly in the Dakotas. However, a severe threat is not expected due to limited large-scale ascent, minimal low-level convergence, and weak deep-layer shear. Elsewhere across the continental U.S., a severe threat is not expected Tuesday and Tuesday night. ..Broyles.. 08/18/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Mon Aug 18 2025 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A severe threat is not expected across the continental U.S. on Tuesday or Tuesday night. ...DISCUSSION... A mid-level ridge will build northward across the central Rockies and northern High Plains on Tuesday, as a subtle shortwave trough moves through the Great Lakes region. At the surface, a cold front will advance southward into the Ohio and mid Mississippi Valleys, extending westward into the southern Plains. As surface temperatures warm during the day, low-level convergence near the front will be favorable for isolated to scattered thunderstorm development. Limited large-scale ascent and weak deep-layer shear will be unfavorable for severe storms. Further northwest into the north-central states, moderate instability will be possible by Tuesday afternoon, mainly in the Dakotas. However, a severe threat is not expected due to limited large-scale ascent, minimal low-level convergence, and weak deep-layer shear. Elsewhere across the continental U.S., a severe threat is not expected Tuesday and Tuesday night. ..Broyles.. 08/18/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Mon Aug 18 2025 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A severe threat is not expected across the continental U.S. on Tuesday or Tuesday night. ...DISCUSSION... A mid-level ridge will build northward across the central Rockies and northern High Plains on Tuesday, as a subtle shortwave trough moves through the Great Lakes region. At the surface, a cold front will advance southward into the Ohio and mid Mississippi Valleys, extending westward into the southern Plains. As surface temperatures warm during the day, low-level convergence near the front will be favorable for isolated to scattered thunderstorm development. Limited large-scale ascent and weak deep-layer shear will be unfavorable for severe storms. Further northwest into the north-central states, moderate instability will be possible by Tuesday afternoon, mainly in the Dakotas. However, a severe threat is not expected due to limited large-scale ascent, minimal low-level convergence, and weak deep-layer shear. Elsewhere across the continental U.S., a severe threat is not expected Tuesday and Tuesday night. ..Broyles.. 08/18/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Mon Aug 18 2025 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A severe threat is not expected across the continental U.S. on Tuesday or Tuesday night. ...DISCUSSION... A mid-level ridge will build northward across the central Rockies and northern High Plains on Tuesday, as a subtle shortwave trough moves through the Great Lakes region. At the surface, a cold front will advance southward into the Ohio and mid Mississippi Valleys, extending westward into the southern Plains. As surface temperatures warm during the day, low-level convergence near the front will be favorable for isolated to scattered thunderstorm development. Limited large-scale ascent and weak deep-layer shear will be unfavorable for severe storms. Further northwest into the north-central states, moderate instability will be possible by Tuesday afternoon, mainly in the Dakotas. However, a severe threat is not expected due to limited large-scale ascent, minimal low-level convergence, and weak deep-layer shear. Elsewhere across the continental U.S., a severe threat is not expected Tuesday and Tuesday night. ..Broyles.. 08/18/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Mon Aug 18 2025 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A severe threat is not expected across the continental U.S. on Tuesday or Tuesday night. ...DISCUSSION... A mid-level ridge will build northward across the central Rockies and northern High Plains on Tuesday, as a subtle shortwave trough moves through the Great Lakes region. At the surface, a cold front will advance southward into the Ohio and mid Mississippi Valleys, extending westward into the southern Plains. As surface temperatures warm during the day, low-level convergence near the front will be favorable for isolated to scattered thunderstorm development. Limited large-scale ascent and weak deep-layer shear will be unfavorable for severe storms. Further northwest into the north-central states, moderate instability will be possible by Tuesday afternoon, mainly in the Dakotas. However, a severe threat is not expected due to limited large-scale ascent, minimal low-level convergence, and weak deep-layer shear. Elsewhere across the continental U.S., a severe threat is not expected Tuesday and Tuesday night. ..Broyles.. 08/18/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Mon Aug 18 2025 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A severe threat is not expected across the continental U.S. on Tuesday or Tuesday night. ...DISCUSSION... A mid-level ridge will build northward across the central Rockies and northern High Plains on Tuesday, as a subtle shortwave trough moves through the Great Lakes region. At the surface, a cold front will advance southward into the Ohio and mid Mississippi Valleys, extending westward into the southern Plains. As surface temperatures warm during the day, low-level convergence near the front will be favorable for isolated to scattered thunderstorm development. Limited large-scale ascent and weak deep-layer shear will be unfavorable for severe storms. Further northwest into the north-central states, moderate instability will be possible by Tuesday afternoon, mainly in the Dakotas. However, a severe threat is not expected due to limited large-scale ascent, minimal low-level convergence, and weak deep-layer shear. Elsewhere across the continental U.S., a severe threat is not expected Tuesday and Tuesday night. ..Broyles.. 08/18/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Mon Aug 18 2025 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A severe threat is not expected across the continental U.S. on Tuesday or Tuesday night. ...DISCUSSION... A mid-level ridge will build northward across the central Rockies and northern High Plains on Tuesday, as a subtle shortwave trough moves through the Great Lakes region. At the surface, a cold front will advance southward into the Ohio and mid Mississippi Valleys, extending westward into the southern Plains. As surface temperatures warm during the day, low-level convergence near the front will be favorable for isolated to scattered thunderstorm development. Limited large-scale ascent and weak deep-layer shear will be unfavorable for severe storms. Further northwest into the north-central states, moderate instability will be possible by Tuesday afternoon, mainly in the Dakotas. However, a severe threat is not expected due to limited large-scale ascent, minimal low-level convergence, and weak deep-layer shear. Elsewhere across the continental U.S., a severe threat is not expected Tuesday and Tuesday night. ..Broyles.. 08/18/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Mon Aug 18 2025 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A severe threat is not expected across the continental U.S. on Tuesday or Tuesday night. ...DISCUSSION... A mid-level ridge will build northward across the central Rockies and northern High Plains on Tuesday, as a subtle shortwave trough moves through the Great Lakes region. At the surface, a cold front will advance southward into the Ohio and mid Mississippi Valleys, extending westward into the southern Plains. As surface temperatures warm during the day, low-level convergence near the front will be favorable for isolated to scattered thunderstorm development. Limited large-scale ascent and weak deep-layer shear will be unfavorable for severe storms. Further northwest into the north-central states, moderate instability will be possible by Tuesday afternoon, mainly in the Dakotas. However, a severe threat is not expected due to limited large-scale ascent, minimal low-level convergence, and weak deep-layer shear. Elsewhere across the continental U.S., a severe threat is not expected Tuesday and Tuesday night. ..Broyles.. 08/18/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Mon Aug 18 2025 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A severe threat is not expected across the continental U.S. on Tuesday or Tuesday night. ...DISCUSSION... A mid-level ridge will build northward across the central Rockies and northern High Plains on Tuesday, as a subtle shortwave trough moves through the Great Lakes region. At the surface, a cold front will advance southward into the Ohio and mid Mississippi Valleys, extending westward into the southern Plains. As surface temperatures warm during the day, low-level convergence near the front will be favorable for isolated to scattered thunderstorm development. Limited large-scale ascent and weak deep-layer shear will be unfavorable for severe storms. Further northwest into the north-central states, moderate instability will be possible by Tuesday afternoon, mainly in the Dakotas. However, a severe threat is not expected due to limited large-scale ascent, minimal low-level convergence, and weak deep-layer shear. Elsewhere across the continental U.S., a severe threat is not expected Tuesday and Tuesday night. ..Broyles.. 08/18/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Mon Aug 18 2025 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Upper Midwest today. Isolated to widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...Central High Plains... A broad upper trough over the northern Plains will move east today with an attendant surface low and cold front also moving east. Behind the departing surface low, weak upslope flow is expected across portions of western SD, northeastern WY. Strong heating and steep mid-level lapse rates should allow for diurnal destabilization with widely scattered thunderstorms expected along a lee trough by the afternoon. Elongated hodographs, courtesy of 30-40 kt of westerly flow aloft, will allow for some organized storms including supercells or clusters. Steep mid-level lapse rates, and moderate buoyancy will support a hail risk. Farther south, stronger heating and mixing will limit low-level moisture across southeastern WY and northeastern CO. Still, enough CAPE should be present for scattered high-based storms near peak heating. The steep low-level lapse rates and any clustering that develops should support damaging winds as storms spread eastward into northeast CO and western NE. Some potential exists for a longer-lived cluster to spread eastward into central/eastern NE and northern KS overnight. Should this occur, damaging winds and some hail would be the primary concerns, though this scenario remains highly uncertain given weaker forecast low-level jet. ...Midwest... One or more clusters of thunderstorms or an MCV is expected to be ongoing at the start of the period in the vicinity of the warm front across portions of IA/MN, casting significant uncertainty on the overall convective evolution for the day. Filtered diurnal heating and nebulous ascent from the broad trough over the northern Plains could support continuation of these storms and additional development into southern WI and northern IL this afternoon. While complications abound, substantial buoyancy (3000-4000 J/kg of MLCAPE) and dewpoints in the mid 70s F south of the composite front/remnant outflow will be supportive of occasional vigorous updrafts. Modest enhancement of the mid and upper-level flow could support a few semi-organized clusters or transient supercells with damaging wind potential. Given the potential for outflow or thunderstorm clusters to significantly alter the environment, confidence in higher wind probabilities is low. ...Southwest into central Montana... Despite a strong ridge building into the northern Rockies, sufficient moisture may promote thunderstorm development in the higher terrain this afternoon. 20-30 kt of flow aloft will be sufficient to support at least marginally organized storms. However, strong mixing during the afternoon could limit buoyancy and storm coverage. Occasional strong, gusty outflow winds are possible with any high-based storms, but confidence in severe potential remains low. ..Lyons/Kerr.. 08/18/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Mon Aug 18 2025 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Upper Midwest today. Isolated to widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...Central High Plains... A broad upper trough over the northern Plains will move east today with an attendant surface low and cold front also moving east. Behind the departing surface low, weak upslope flow is expected across portions of western SD, northeastern WY. Strong heating and steep mid-level lapse rates should allow for diurnal destabilization with widely scattered thunderstorms expected along a lee trough by the afternoon. Elongated hodographs, courtesy of 30-40 kt of westerly flow aloft, will allow for some organized storms including supercells or clusters. Steep mid-level lapse rates, and moderate buoyancy will support a hail risk. Farther south, stronger heating and mixing will limit low-level moisture across southeastern WY and northeastern CO. Still, enough CAPE should be present for scattered high-based storms near peak heating. The steep low-level lapse rates and any clustering that develops should support damaging winds as storms spread eastward into northeast CO and western NE. Some potential exists for a longer-lived cluster to spread eastward into central/eastern NE and northern KS overnight. Should this occur, damaging winds and some hail would be the primary concerns, though this scenario remains highly uncertain given weaker forecast low-level jet. ...Midwest... One or more clusters of thunderstorms or an MCV is expected to be ongoing at the start of the period in the vicinity of the warm front across portions of IA/MN, casting significant uncertainty on the overall convective evolution for the day. Filtered diurnal heating and nebulous ascent from the broad trough over the northern Plains could support continuation of these storms and additional development into southern WI and northern IL this afternoon. While complications abound, substantial buoyancy (3000-4000 J/kg of MLCAPE) and dewpoints in the mid 70s F south of the composite front/remnant outflow will be supportive of occasional vigorous updrafts. Modest enhancement of the mid and upper-level flow could support a few semi-organized clusters or transient supercells with damaging wind potential. Given the potential for outflow or thunderstorm clusters to significantly alter the environment, confidence in higher wind probabilities is low. ...Southwest into central Montana... Despite a strong ridge building into the northern Rockies, sufficient moisture may promote thunderstorm development in the higher terrain this afternoon. 20-30 kt of flow aloft will be sufficient to support at least marginally organized storms. However, strong mixing during the afternoon could limit buoyancy and storm coverage. Occasional strong, gusty outflow winds are possible with any high-based storms, but confidence in severe potential remains low. ..Lyons/Kerr.. 08/18/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Mon Aug 18 2025 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Upper Midwest today. Isolated to widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...Central High Plains... A broad upper trough over the northern Plains will move east today with an attendant surface low and cold front also moving east. Behind the departing surface low, weak upslope flow is expected across portions of western SD, northeastern WY. Strong heating and steep mid-level lapse rates should allow for diurnal destabilization with widely scattered thunderstorms expected along a lee trough by the afternoon. Elongated hodographs, courtesy of 30-40 kt of westerly flow aloft, will allow for some organized storms including supercells or clusters. Steep mid-level lapse rates, and moderate buoyancy will support a hail risk. Farther south, stronger heating and mixing will limit low-level moisture across southeastern WY and northeastern CO. Still, enough CAPE should be present for scattered high-based storms near peak heating. The steep low-level lapse rates and any clustering that develops should support damaging winds as storms spread eastward into northeast CO and western NE. Some potential exists for a longer-lived cluster to spread eastward into central/eastern NE and northern KS overnight. Should this occur, damaging winds and some hail would be the primary concerns, though this scenario remains highly uncertain given weaker forecast low-level jet. ...Midwest... One or more clusters of thunderstorms or an MCV is expected to be ongoing at the start of the period in the vicinity of the warm front across portions of IA/MN, casting significant uncertainty on the overall convective evolution for the day. Filtered diurnal heating and nebulous ascent from the broad trough over the northern Plains could support continuation of these storms and additional development into southern WI and northern IL this afternoon. While complications abound, substantial buoyancy (3000-4000 J/kg of MLCAPE) and dewpoints in the mid 70s F south of the composite front/remnant outflow will be supportive of occasional vigorous updrafts. Modest enhancement of the mid and upper-level flow could support a few semi-organized clusters or transient supercells with damaging wind potential. Given the potential for outflow or thunderstorm clusters to significantly alter the environment, confidence in higher wind probabilities is low. ...Southwest into central Montana... Despite a strong ridge building into the northern Rockies, sufficient moisture may promote thunderstorm development in the higher terrain this afternoon. 20-30 kt of flow aloft will be sufficient to support at least marginally organized storms. However, strong mixing during the afternoon could limit buoyancy and storm coverage. Occasional strong, gusty outflow winds are possible with any high-based storms, but confidence in severe potential remains low. ..Lyons/Kerr.. 08/18/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Mon Aug 18 2025 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Upper Midwest today. Isolated to widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...Central High Plains... A broad upper trough over the northern Plains will move east today with an attendant surface low and cold front also moving east. Behind the departing surface low, weak upslope flow is expected across portions of western SD, northeastern WY. Strong heating and steep mid-level lapse rates should allow for diurnal destabilization with widely scattered thunderstorms expected along a lee trough by the afternoon. Elongated hodographs, courtesy of 30-40 kt of westerly flow aloft, will allow for some organized storms including supercells or clusters. Steep mid-level lapse rates, and moderate buoyancy will support a hail risk. Farther south, stronger heating and mixing will limit low-level moisture across southeastern WY and northeastern CO. Still, enough CAPE should be present for scattered high-based storms near peak heating. The steep low-level lapse rates and any clustering that develops should support damaging winds as storms spread eastward into northeast CO and western NE. Some potential exists for a longer-lived cluster to spread eastward into central/eastern NE and northern KS overnight. Should this occur, damaging winds and some hail would be the primary concerns, though this scenario remains highly uncertain given weaker forecast low-level jet. ...Midwest... One or more clusters of thunderstorms or an MCV is expected to be ongoing at the start of the period in the vicinity of the warm front across portions of IA/MN, casting significant uncertainty on the overall convective evolution for the day. Filtered diurnal heating and nebulous ascent from the broad trough over the northern Plains could support continuation of these storms and additional development into southern WI and northern IL this afternoon. While complications abound, substantial buoyancy (3000-4000 J/kg of MLCAPE) and dewpoints in the mid 70s F south of the composite front/remnant outflow will be supportive of occasional vigorous updrafts. Modest enhancement of the mid and upper-level flow could support a few semi-organized clusters or transient supercells with damaging wind potential. Given the potential for outflow or thunderstorm clusters to significantly alter the environment, confidence in higher wind probabilities is low. ...Southwest into central Montana... Despite a strong ridge building into the northern Rockies, sufficient moisture may promote thunderstorm development in the higher terrain this afternoon. 20-30 kt of flow aloft will be sufficient to support at least marginally organized storms. However, strong mixing during the afternoon could limit buoyancy and storm coverage. Occasional strong, gusty outflow winds are possible with any high-based storms, but confidence in severe potential remains low. ..Lyons/Kerr.. 08/18/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Mon Aug 18 2025 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Upper Midwest today. Isolated to widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...Central High Plains... A broad upper trough over the northern Plains will move east today with an attendant surface low and cold front also moving east. Behind the departing surface low, weak upslope flow is expected across portions of western SD, northeastern WY. Strong heating and steep mid-level lapse rates should allow for diurnal destabilization with widely scattered thunderstorms expected along a lee trough by the afternoon. Elongated hodographs, courtesy of 30-40 kt of westerly flow aloft, will allow for some organized storms including supercells or clusters. Steep mid-level lapse rates, and moderate buoyancy will support a hail risk. Farther south, stronger heating and mixing will limit low-level moisture across southeastern WY and northeastern CO. Still, enough CAPE should be present for scattered high-based storms near peak heating. The steep low-level lapse rates and any clustering that develops should support damaging winds as storms spread eastward into northeast CO and western NE. Some potential exists for a longer-lived cluster to spread eastward into central/eastern NE and northern KS overnight. Should this occur, damaging winds and some hail would be the primary concerns, though this scenario remains highly uncertain given weaker forecast low-level jet. ...Midwest... One or more clusters of thunderstorms or an MCV is expected to be ongoing at the start of the period in the vicinity of the warm front across portions of IA/MN, casting significant uncertainty on the overall convective evolution for the day. Filtered diurnal heating and nebulous ascent from the broad trough over the northern Plains could support continuation of these storms and additional development into southern WI and northern IL this afternoon. While complications abound, substantial buoyancy (3000-4000 J/kg of MLCAPE) and dewpoints in the mid 70s F south of the composite front/remnant outflow will be supportive of occasional vigorous updrafts. Modest enhancement of the mid and upper-level flow could support a few semi-organized clusters or transient supercells with damaging wind potential. Given the potential for outflow or thunderstorm clusters to significantly alter the environment, confidence in higher wind probabilities is low. ...Southwest into central Montana... Despite a strong ridge building into the northern Rockies, sufficient moisture may promote thunderstorm development in the higher terrain this afternoon. 20-30 kt of flow aloft will be sufficient to support at least marginally organized storms. However, strong mixing during the afternoon could limit buoyancy and storm coverage. Occasional strong, gusty outflow winds are possible with any high-based storms, but confidence in severe potential remains low. ..Lyons/Kerr.. 08/18/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Mon Aug 18 2025 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Upper Midwest today. Isolated to widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...Central High Plains... A broad upper trough over the northern Plains will move east today with an attendant surface low and cold front also moving east. Behind the departing surface low, weak upslope flow is expected across portions of western SD, northeastern WY. Strong heating and steep mid-level lapse rates should allow for diurnal destabilization with widely scattered thunderstorms expected along a lee trough by the afternoon. Elongated hodographs, courtesy of 30-40 kt of westerly flow aloft, will allow for some organized storms including supercells or clusters. Steep mid-level lapse rates, and moderate buoyancy will support a hail risk. Farther south, stronger heating and mixing will limit low-level moisture across southeastern WY and northeastern CO. Still, enough CAPE should be present for scattered high-based storms near peak heating. The steep low-level lapse rates and any clustering that develops should support damaging winds as storms spread eastward into northeast CO and western NE. Some potential exists for a longer-lived cluster to spread eastward into central/eastern NE and northern KS overnight. Should this occur, damaging winds and some hail would be the primary concerns, though this scenario remains highly uncertain given weaker forecast low-level jet. ...Midwest... One or more clusters of thunderstorms or an MCV is expected to be ongoing at the start of the period in the vicinity of the warm front across portions of IA/MN, casting significant uncertainty on the overall convective evolution for the day. Filtered diurnal heating and nebulous ascent from the broad trough over the northern Plains could support continuation of these storms and additional development into southern WI and northern IL this afternoon. While complications abound, substantial buoyancy (3000-4000 J/kg of MLCAPE) and dewpoints in the mid 70s F south of the composite front/remnant outflow will be supportive of occasional vigorous updrafts. Modest enhancement of the mid and upper-level flow could support a few semi-organized clusters or transient supercells with damaging wind potential. Given the potential for outflow or thunderstorm clusters to significantly alter the environment, confidence in higher wind probabilities is low. ...Southwest into central Montana... Despite a strong ridge building into the northern Rockies, sufficient moisture may promote thunderstorm development in the higher terrain this afternoon. 20-30 kt of flow aloft will be sufficient to support at least marginally organized storms. However, strong mixing during the afternoon could limit buoyancy and storm coverage. Occasional strong, gusty outflow winds are possible with any high-based storms, but confidence in severe potential remains low. ..Lyons/Kerr.. 08/18/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Mon Aug 18 2025 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Upper Midwest today. Isolated to widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...Central High Plains... A broad upper trough over the northern Plains will move east today with an attendant surface low and cold front also moving east. Behind the departing surface low, weak upslope flow is expected across portions of western SD, northeastern WY. Strong heating and steep mid-level lapse rates should allow for diurnal destabilization with widely scattered thunderstorms expected along a lee trough by the afternoon. Elongated hodographs, courtesy of 30-40 kt of westerly flow aloft, will allow for some organized storms including supercells or clusters. Steep mid-level lapse rates, and moderate buoyancy will support a hail risk. Farther south, stronger heating and mixing will limit low-level moisture across southeastern WY and northeastern CO. Still, enough CAPE should be present for scattered high-based storms near peak heating. The steep low-level lapse rates and any clustering that develops should support damaging winds as storms spread eastward into northeast CO and western NE. Some potential exists for a longer-lived cluster to spread eastward into central/eastern NE and northern KS overnight. Should this occur, damaging winds and some hail would be the primary concerns, though this scenario remains highly uncertain given weaker forecast low-level jet. ...Midwest... One or more clusters of thunderstorms or an MCV is expected to be ongoing at the start of the period in the vicinity of the warm front across portions of IA/MN, casting significant uncertainty on the overall convective evolution for the day. Filtered diurnal heating and nebulous ascent from the broad trough over the northern Plains could support continuation of these storms and additional development into southern WI and northern IL this afternoon. While complications abound, substantial buoyancy (3000-4000 J/kg of MLCAPE) and dewpoints in the mid 70s F south of the composite front/remnant outflow will be supportive of occasional vigorous updrafts. Modest enhancement of the mid and upper-level flow could support a few semi-organized clusters or transient supercells with damaging wind potential. Given the potential for outflow or thunderstorm clusters to significantly alter the environment, confidence in higher wind probabilities is low. ...Southwest into central Montana... Despite a strong ridge building into the northern Rockies, sufficient moisture may promote thunderstorm development in the higher terrain this afternoon. 20-30 kt of flow aloft will be sufficient to support at least marginally organized storms. However, strong mixing during the afternoon could limit buoyancy and storm coverage. Occasional strong, gusty outflow winds are possible with any high-based storms, but confidence in severe potential remains low. ..Lyons/Kerr.. 08/18/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Mon Aug 18 2025 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Upper Midwest today. Isolated to widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...Central High Plains... A broad upper trough over the northern Plains will move east today with an attendant surface low and cold front also moving east. Behind the departing surface low, weak upslope flow is expected across portions of western SD, northeastern WY. Strong heating and steep mid-level lapse rates should allow for diurnal destabilization with widely scattered thunderstorms expected along a lee trough by the afternoon. Elongated hodographs, courtesy of 30-40 kt of westerly flow aloft, will allow for some organized storms including supercells or clusters. Steep mid-level lapse rates, and moderate buoyancy will support a hail risk. Farther south, stronger heating and mixing will limit low-level moisture across southeastern WY and northeastern CO. Still, enough CAPE should be present for scattered high-based storms near peak heating. The steep low-level lapse rates and any clustering that develops should support damaging winds as storms spread eastward into northeast CO and western NE. Some potential exists for a longer-lived cluster to spread eastward into central/eastern NE and northern KS overnight. Should this occur, damaging winds and some hail would be the primary concerns, though this scenario remains highly uncertain given weaker forecast low-level jet. ...Midwest... One or more clusters of thunderstorms or an MCV is expected to be ongoing at the start of the period in the vicinity of the warm front across portions of IA/MN, casting significant uncertainty on the overall convective evolution for the day. Filtered diurnal heating and nebulous ascent from the broad trough over the northern Plains could support continuation of these storms and additional development into southern WI and northern IL this afternoon. While complications abound, substantial buoyancy (3000-4000 J/kg of MLCAPE) and dewpoints in the mid 70s F south of the composite front/remnant outflow will be supportive of occasional vigorous updrafts. Modest enhancement of the mid and upper-level flow could support a few semi-organized clusters or transient supercells with damaging wind potential. Given the potential for outflow or thunderstorm clusters to significantly alter the environment, confidence in higher wind probabilities is low. ...Southwest into central Montana... Despite a strong ridge building into the northern Rockies, sufficient moisture may promote thunderstorm development in the higher terrain this afternoon. 20-30 kt of flow aloft will be sufficient to support at least marginally organized storms. However, strong mixing during the afternoon could limit buoyancy and storm coverage. Occasional strong, gusty outflow winds are possible with any high-based storms, but confidence in severe potential remains low. ..Lyons/Kerr.. 08/18/2025 Read more