Severe Storms

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Fri Jun 20 2025 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE NORTHERN GREAT LAKES INTO NEW YORK AND NORTHERN PENNSYLVANIA... ...SUMMARY... Strong to locally severe storms are possible Saturday from the northern Great Plains into the Upper Midwest and Great Lakes. ...Synopsis... An amplifying pattern will occur on Saturday with a trough strengthening across the west with a ridge building across the eastern CONUS. Surface high pressure will be present across the eastern CONUS with lee troughing across the central and northern Plains ahead of the strengthening western CONUS trough. ...Great Lakes into the Northeast... A strong MCS will likely be ongoing at the beginning of the period across northern Wisconsin/western Upper Michigan. This MCS will likely continue east through the morning with some wind/hail threat across Upper Michigan and northern Lower Michigan before eventually moving into Ontario. If this MCS continues to track along the instability gradient, it could eventually arrive across western/central New York during the afternoon/evening. However, this threat is conditional given stronger forcing farther north in Canada and strong building heights across the Northeast. Additional thunderstorms may develop along the trailing outflow/composite boundary during the afternoon as strong instability builds into the northern Great Lakes. However, building heights aloft should mostly suppress convection, with only isolated storm coverage expected, if at all. If any storms can develop, the environment would be very favorable for large hail, severe wind gusts, and perhaps a tornado. ...Northern Plains into the Upper Midwest... Very strong instability is expected to build across the northern Plains on Saturday afternoon/evening. Very warm 700mb temperatures (16C) and building heights aloft should keep thunderstorm activity suppressed for much of the period. However, strong heating could allow for isolated storm development which would likely be supercellular with a hail and wind threat if this conditional threat does materialize. A few strong to potentially severe storms may be ongoing at the beginning of the period across eastern Montana as a weak mid-level trough traverses the region. Storm activity will likely remain limited across eastern Montana for much of the day as heights build aloft. However, additional storms may develop early Sunday morning as troughing starts to advance east. Limited instability is the primary limiting factor, but if sufficient instability can develop, a few strong to severe storms may be possible (12Z NSSL WRF). ..Bentley.. 06/20/2025 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1137 AM CDT Fri Jun 20 2025 Valid 201700Z - 211200Z ...CRITICAL FIRE WEATHER AREA FOR FOUR CORNERS AND GREAT BASIN... No changes are needed to the current D1 Fire Weather Outlook. Morning satellite analysis shows mostly sunny skies across the Critical area, with relative humidity ranging from 15-20 percent and winds gusting 20-30 mph. HREF guidance continues to indicate that several hours of Critical conditions are likely from the Great Basin to the Four Corners and into portions of the High Plains through this afternoon. See previous discussion below for more information. ..Thornton.. 06/20/2025 .PREV DISCUSSION... /ISSUED 0132 AM CDT Fri Jun 20 2025/ ...Synopsis... Widespread critical fire weather conditions are expected today across parts of the Greater Four Corners region and the Great Basin. Early-morning water vapor imagery shows a dominant upper ridge over the central CONUS with shortwave troughing over the western Great Basin and northeastern Pacific. The Great Basin shortwave is forecast to move into the northern High Plains through the afternoon, which will facilitate surface low development across eastern WY by late afternoon. Strengthening low-level winds in response to the deepening low will promote a widespread swath of 20-30 mph winds within a very dry air mass and across a region with receptive fuels. ...Four Corners into the High Plains... The axis of the mid-level jet associated with the leading shortwave is forecast to reside from southeast UT into southern WY by peak heating. This will maximize the potential for 20+ mph winds at the surface, and will likely support wind gusts between 30-45 mph. RH values in the single digits to low teens coupled with antecedent dry fuels (active fires were recently noted across southern UT in GOES IR imagery) will support widespread and prolonged critical conditions with periods of extremely critical wind speeds possible - especially across south-central WY. Elevated to critical fire weather conditions will likely extend well to the northeast into the central High Plains, and possibly as far east and western South Dakota behind an eastward surging dry line. However, fuel conditions generally improve with eastward extent due to recent rainfall. Fire risk highlights have been expanded northeast to account for the strong wind/RH signal, but Critical highlights were focused across areas with dry, receptive fuels. ...Nevada into adjacent portions of Idaho and Utah... Southwesterly flow over the southern to central Sierra Nevada will induce strong downslope flow into western and central NV, spreading into southeast ID and western UT by late afternoon. Guidance continues to show a strong signal for 20-25 mph winds through much of the afternoon, and single-digit RH values should support widespread critical fire weather conditions. ...Southern California into the San Joaquin Valley... A strong onshore pressure gradient will support increasing downslope winds on the leeward side/eastern slopes of the coastal ranges across southern California this afternoon. Relative humidities values falling into the teens within the downslope regime, coupled with dry grasses, will support a fire weather concern. ...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 1137 AM CDT Fri Jun 20 2025 Valid 201700Z - 211200Z ...CRITICAL FIRE WEATHER AREA FOR FOUR CORNERS AND GREAT BASIN... No changes are needed to the current D1 Fire Weather Outlook. Morning satellite analysis shows mostly sunny skies across the Critical area, with relative humidity ranging from 15-20 percent and winds gusting 20-30 mph. HREF guidance continues to indicate that several hours of Critical conditions are likely from the Great Basin to the Four Corners and into portions of the High Plains through this afternoon. See previous discussion below for more information. ..Thornton.. 06/20/2025 .PREV DISCUSSION... /ISSUED 0132 AM CDT Fri Jun 20 2025/ ...Synopsis... Widespread critical fire weather conditions are expected today across parts of the Greater Four Corners region and the Great Basin. Early-morning water vapor imagery shows a dominant upper ridge over the central CONUS with shortwave troughing over the western Great Basin and northeastern Pacific. The Great Basin shortwave is forecast to move into the northern High Plains through the afternoon, which will facilitate surface low development across eastern WY by late afternoon. Strengthening low-level winds in response to the deepening low will promote a widespread swath of 20-30 mph winds within a very dry air mass and across a region with receptive fuels. ...Four Corners into the High Plains... The axis of the mid-level jet associated with the leading shortwave is forecast to reside from southeast UT into southern WY by peak heating. This will maximize the potential for 20+ mph winds at the surface, and will likely support wind gusts between 30-45 mph. RH values in the single digits to low teens coupled with antecedent dry fuels (active fires were recently noted across southern UT in GOES IR imagery) will support widespread and prolonged critical conditions with periods of extremely critical wind speeds possible - especially across south-central WY. Elevated to critical fire weather conditions will likely extend well to the northeast into the central High Plains, and possibly as far east and western South Dakota behind an eastward surging dry line. However, fuel conditions generally improve with eastward extent due to recent rainfall. Fire risk highlights have been expanded northeast to account for the strong wind/RH signal, but Critical highlights were focused across areas with dry, receptive fuels. ...Nevada into adjacent portions of Idaho and Utah... Southwesterly flow over the southern to central Sierra Nevada will induce strong downslope flow into western and central NV, spreading into southeast ID and western UT by late afternoon. Guidance continues to show a strong signal for 20-25 mph winds through much of the afternoon, and single-digit RH values should support widespread critical fire weather conditions. ...Southern California into the San Joaquin Valley... A strong onshore pressure gradient will support increasing downslope winds on the leeward side/eastern slopes of the coastal ranges across southern California this afternoon. Relative humidities values falling into the teens within the downslope regime, coupled with dry grasses, will support a fire weather concern. ...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 1137 AM CDT Fri Jun 20 2025 Valid 201700Z - 211200Z ...CRITICAL FIRE WEATHER AREA FOR FOUR CORNERS AND GREAT BASIN... No changes are needed to the current D1 Fire Weather Outlook. Morning satellite analysis shows mostly sunny skies across the Critical area, with relative humidity ranging from 15-20 percent and winds gusting 20-30 mph. HREF guidance continues to indicate that several hours of Critical conditions are likely from the Great Basin to the Four Corners and into portions of the High Plains through this afternoon. See previous discussion below for more information. ..Thornton.. 06/20/2025 .PREV DISCUSSION... /ISSUED 0132 AM CDT Fri Jun 20 2025/ ...Synopsis... Widespread critical fire weather conditions are expected today across parts of the Greater Four Corners region and the Great Basin. Early-morning water vapor imagery shows a dominant upper ridge over the central CONUS with shortwave troughing over the western Great Basin and northeastern Pacific. The Great Basin shortwave is forecast to move into the northern High Plains through the afternoon, which will facilitate surface low development across eastern WY by late afternoon. Strengthening low-level winds in response to the deepening low will promote a widespread swath of 20-30 mph winds within a very dry air mass and across a region with receptive fuels. ...Four Corners into the High Plains... The axis of the mid-level jet associated with the leading shortwave is forecast to reside from southeast UT into southern WY by peak heating. This will maximize the potential for 20+ mph winds at the surface, and will likely support wind gusts between 30-45 mph. RH values in the single digits to low teens coupled with antecedent dry fuels (active fires were recently noted across southern UT in GOES IR imagery) will support widespread and prolonged critical conditions with periods of extremely critical wind speeds possible - especially across south-central WY. Elevated to critical fire weather conditions will likely extend well to the northeast into the central High Plains, and possibly as far east and western South Dakota behind an eastward surging dry line. However, fuel conditions generally improve with eastward extent due to recent rainfall. Fire risk highlights have been expanded northeast to account for the strong wind/RH signal, but Critical highlights were focused across areas with dry, receptive fuels. ...Nevada into adjacent portions of Idaho and Utah... Southwesterly flow over the southern to central Sierra Nevada will induce strong downslope flow into western and central NV, spreading into southeast ID and western UT by late afternoon. Guidance continues to show a strong signal for 20-25 mph winds through much of the afternoon, and single-digit RH values should support widespread critical fire weather conditions. ...Southern California into the San Joaquin Valley... A strong onshore pressure gradient will support increasing downslope winds on the leeward side/eastern slopes of the coastal ranges across southern California this afternoon. Relative humidities values falling into the teens within the downslope regime, coupled with dry grasses, will support a fire weather concern. ...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 1137 AM CDT Fri Jun 20 2025 Valid 201700Z - 211200Z ...CRITICAL FIRE WEATHER AREA FOR FOUR CORNERS AND GREAT BASIN... No changes are needed to the current D1 Fire Weather Outlook. Morning satellite analysis shows mostly sunny skies across the Critical area, with relative humidity ranging from 15-20 percent and winds gusting 20-30 mph. HREF guidance continues to indicate that several hours of Critical conditions are likely from the Great Basin to the Four Corners and into portions of the High Plains through this afternoon. See previous discussion below for more information. ..Thornton.. 06/20/2025 .PREV DISCUSSION... /ISSUED 0132 AM CDT Fri Jun 20 2025/ ...Synopsis... Widespread critical fire weather conditions are expected today across parts of the Greater Four Corners region and the Great Basin. Early-morning water vapor imagery shows a dominant upper ridge over the central CONUS with shortwave troughing over the western Great Basin and northeastern Pacific. The Great Basin shortwave is forecast to move into the northern High Plains through the afternoon, which will facilitate surface low development across eastern WY by late afternoon. Strengthening low-level winds in response to the deepening low will promote a widespread swath of 20-30 mph winds within a very dry air mass and across a region with receptive fuels. ...Four Corners into the High Plains... The axis of the mid-level jet associated with the leading shortwave is forecast to reside from southeast UT into southern WY by peak heating. This will maximize the potential for 20+ mph winds at the surface, and will likely support wind gusts between 30-45 mph. RH values in the single digits to low teens coupled with antecedent dry fuels (active fires were recently noted across southern UT in GOES IR imagery) will support widespread and prolonged critical conditions with periods of extremely critical wind speeds possible - especially across south-central WY. Elevated to critical fire weather conditions will likely extend well to the northeast into the central High Plains, and possibly as far east and western South Dakota behind an eastward surging dry line. However, fuel conditions generally improve with eastward extent due to recent rainfall. Fire risk highlights have been expanded northeast to account for the strong wind/RH signal, but Critical highlights were focused across areas with dry, receptive fuels. ...Nevada into adjacent portions of Idaho and Utah... Southwesterly flow over the southern to central Sierra Nevada will induce strong downslope flow into western and central NV, spreading into southeast ID and western UT by late afternoon. Guidance continues to show a strong signal for 20-25 mph winds through much of the afternoon, and single-digit RH values should support widespread critical fire weather conditions. ...Southern California into the San Joaquin Valley... A strong onshore pressure gradient will support increasing downslope winds on the leeward side/eastern slopes of the coastal ranges across southern California this afternoon. Relative humidities values falling into the teens within the downslope regime, coupled with dry grasses, will support a fire weather concern. ...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 1137 AM CDT Fri Jun 20 2025 Valid 201700Z - 211200Z ...CRITICAL FIRE WEATHER AREA FOR FOUR CORNERS AND GREAT BASIN... No changes are needed to the current D1 Fire Weather Outlook. Morning satellite analysis shows mostly sunny skies across the Critical area, with relative humidity ranging from 15-20 percent and winds gusting 20-30 mph. HREF guidance continues to indicate that several hours of Critical conditions are likely from the Great Basin to the Four Corners and into portions of the High Plains through this afternoon. See previous discussion below for more information. ..Thornton.. 06/20/2025 .PREV DISCUSSION... /ISSUED 0132 AM CDT Fri Jun 20 2025/ ...Synopsis... Widespread critical fire weather conditions are expected today across parts of the Greater Four Corners region and the Great Basin. Early-morning water vapor imagery shows a dominant upper ridge over the central CONUS with shortwave troughing over the western Great Basin and northeastern Pacific. The Great Basin shortwave is forecast to move into the northern High Plains through the afternoon, which will facilitate surface low development across eastern WY by late afternoon. Strengthening low-level winds in response to the deepening low will promote a widespread swath of 20-30 mph winds within a very dry air mass and across a region with receptive fuels. ...Four Corners into the High Plains... The axis of the mid-level jet associated with the leading shortwave is forecast to reside from southeast UT into southern WY by peak heating. This will maximize the potential for 20+ mph winds at the surface, and will likely support wind gusts between 30-45 mph. RH values in the single digits to low teens coupled with antecedent dry fuels (active fires were recently noted across southern UT in GOES IR imagery) will support widespread and prolonged critical conditions with periods of extremely critical wind speeds possible - especially across south-central WY. Elevated to critical fire weather conditions will likely extend well to the northeast into the central High Plains, and possibly as far east and western South Dakota behind an eastward surging dry line. However, fuel conditions generally improve with eastward extent due to recent rainfall. Fire risk highlights have been expanded northeast to account for the strong wind/RH signal, but Critical highlights were focused across areas with dry, receptive fuels. ...Nevada into adjacent portions of Idaho and Utah... Southwesterly flow over the southern to central Sierra Nevada will induce strong downslope flow into western and central NV, spreading into southeast ID and western UT by late afternoon. Guidance continues to show a strong signal for 20-25 mph winds through much of the afternoon, and single-digit RH values should support widespread critical fire weather conditions. ...Southern California into the San Joaquin Valley... A strong onshore pressure gradient will support increasing downslope winds on the leeward side/eastern slopes of the coastal ranges across southern California this afternoon. Relative humidities values falling into the teens within the downslope regime, coupled with dry grasses, will support a fire weather concern. ...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 1137 AM CDT Fri Jun 20 2025 Valid 201700Z - 211200Z ...CRITICAL FIRE WEATHER AREA FOR FOUR CORNERS AND GREAT BASIN... No changes are needed to the current D1 Fire Weather Outlook. Morning satellite analysis shows mostly sunny skies across the Critical area, with relative humidity ranging from 15-20 percent and winds gusting 20-30 mph. HREF guidance continues to indicate that several hours of Critical conditions are likely from the Great Basin to the Four Corners and into portions of the High Plains through this afternoon. See previous discussion below for more information. ..Thornton.. 06/20/2025 .PREV DISCUSSION... /ISSUED 0132 AM CDT Fri Jun 20 2025/ ...Synopsis... Widespread critical fire weather conditions are expected today across parts of the Greater Four Corners region and the Great Basin. Early-morning water vapor imagery shows a dominant upper ridge over the central CONUS with shortwave troughing over the western Great Basin and northeastern Pacific. The Great Basin shortwave is forecast to move into the northern High Plains through the afternoon, which will facilitate surface low development across eastern WY by late afternoon. Strengthening low-level winds in response to the deepening low will promote a widespread swath of 20-30 mph winds within a very dry air mass and across a region with receptive fuels. ...Four Corners into the High Plains... The axis of the mid-level jet associated with the leading shortwave is forecast to reside from southeast UT into southern WY by peak heating. This will maximize the potential for 20+ mph winds at the surface, and will likely support wind gusts between 30-45 mph. RH values in the single digits to low teens coupled with antecedent dry fuels (active fires were recently noted across southern UT in GOES IR imagery) will support widespread and prolonged critical conditions with periods of extremely critical wind speeds possible - especially across south-central WY. Elevated to critical fire weather conditions will likely extend well to the northeast into the central High Plains, and possibly as far east and western South Dakota behind an eastward surging dry line. However, fuel conditions generally improve with eastward extent due to recent rainfall. Fire risk highlights have been expanded northeast to account for the strong wind/RH signal, but Critical highlights were focused across areas with dry, receptive fuels. ...Nevada into adjacent portions of Idaho and Utah... Southwesterly flow over the southern to central Sierra Nevada will induce strong downslope flow into western and central NV, spreading into southeast ID and western UT by late afternoon. Guidance continues to show a strong signal for 20-25 mph winds through much of the afternoon, and single-digit RH values should support widespread critical fire weather conditions. ...Southern California into the San Joaquin Valley... A strong onshore pressure gradient will support increasing downslope winds on the leeward side/eastern slopes of the coastal ranges across southern California this afternoon. Relative humidities values falling into the teens within the downslope regime, coupled with dry grasses, will support a fire weather concern. ...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 1137 AM CDT Fri Jun 20 2025 Valid 201700Z - 211200Z ...CRITICAL FIRE WEATHER AREA FOR FOUR CORNERS AND GREAT BASIN... No changes are needed to the current D1 Fire Weather Outlook. Morning satellite analysis shows mostly sunny skies across the Critical area, with relative humidity ranging from 15-20 percent and winds gusting 20-30 mph. HREF guidance continues to indicate that several hours of Critical conditions are likely from the Great Basin to the Four Corners and into portions of the High Plains through this afternoon. See previous discussion below for more information. ..Thornton.. 06/20/2025 .PREV DISCUSSION... /ISSUED 0132 AM CDT Fri Jun 20 2025/ ...Synopsis... Widespread critical fire weather conditions are expected today across parts of the Greater Four Corners region and the Great Basin. Early-morning water vapor imagery shows a dominant upper ridge over the central CONUS with shortwave troughing over the western Great Basin and northeastern Pacific. The Great Basin shortwave is forecast to move into the northern High Plains through the afternoon, which will facilitate surface low development across eastern WY by late afternoon. Strengthening low-level winds in response to the deepening low will promote a widespread swath of 20-30 mph winds within a very dry air mass and across a region with receptive fuels. ...Four Corners into the High Plains... The axis of the mid-level jet associated with the leading shortwave is forecast to reside from southeast UT into southern WY by peak heating. This will maximize the potential for 20+ mph winds at the surface, and will likely support wind gusts between 30-45 mph. RH values in the single digits to low teens coupled with antecedent dry fuels (active fires were recently noted across southern UT in GOES IR imagery) will support widespread and prolonged critical conditions with periods of extremely critical wind speeds possible - especially across south-central WY. Elevated to critical fire weather conditions will likely extend well to the northeast into the central High Plains, and possibly as far east and western South Dakota behind an eastward surging dry line. However, fuel conditions generally improve with eastward extent due to recent rainfall. Fire risk highlights have been expanded northeast to account for the strong wind/RH signal, but Critical highlights were focused across areas with dry, receptive fuels. ...Nevada into adjacent portions of Idaho and Utah... Southwesterly flow over the southern to central Sierra Nevada will induce strong downslope flow into western and central NV, spreading into southeast ID and western UT by late afternoon. Guidance continues to show a strong signal for 20-25 mph winds through much of the afternoon, and single-digit RH values should support widespread critical fire weather conditions. ...Southern California into the San Joaquin Valley... A strong onshore pressure gradient will support increasing downslope winds on the leeward side/eastern slopes of the coastal ranges across southern California this afternoon. Relative humidities values falling into the teens within the downslope regime, coupled with dry grasses, will support a fire weather concern. ...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 1137 AM CDT Fri Jun 20 2025 Valid 201700Z - 211200Z ...CRITICAL FIRE WEATHER AREA FOR FOUR CORNERS AND GREAT BASIN... No changes are needed to the current D1 Fire Weather Outlook. Morning satellite analysis shows mostly sunny skies across the Critical area, with relative humidity ranging from 15-20 percent and winds gusting 20-30 mph. HREF guidance continues to indicate that several hours of Critical conditions are likely from the Great Basin to the Four Corners and into portions of the High Plains through this afternoon. See previous discussion below for more information. ..Thornton.. 06/20/2025 .PREV DISCUSSION... /ISSUED 0132 AM CDT Fri Jun 20 2025/ ...Synopsis... Widespread critical fire weather conditions are expected today across parts of the Greater Four Corners region and the Great Basin. Early-morning water vapor imagery shows a dominant upper ridge over the central CONUS with shortwave troughing over the western Great Basin and northeastern Pacific. The Great Basin shortwave is forecast to move into the northern High Plains through the afternoon, which will facilitate surface low development across eastern WY by late afternoon. Strengthening low-level winds in response to the deepening low will promote a widespread swath of 20-30 mph winds within a very dry air mass and across a region with receptive fuels. ...Four Corners into the High Plains... The axis of the mid-level jet associated with the leading shortwave is forecast to reside from southeast UT into southern WY by peak heating. This will maximize the potential for 20+ mph winds at the surface, and will likely support wind gusts between 30-45 mph. RH values in the single digits to low teens coupled with antecedent dry fuels (active fires were recently noted across southern UT in GOES IR imagery) will support widespread and prolonged critical conditions with periods of extremely critical wind speeds possible - especially across south-central WY. Elevated to critical fire weather conditions will likely extend well to the northeast into the central High Plains, and possibly as far east and western South Dakota behind an eastward surging dry line. However, fuel conditions generally improve with eastward extent due to recent rainfall. Fire risk highlights have been expanded northeast to account for the strong wind/RH signal, but Critical highlights were focused across areas with dry, receptive fuels. ...Nevada into adjacent portions of Idaho and Utah... Southwesterly flow over the southern to central Sierra Nevada will induce strong downslope flow into western and central NV, spreading into southeast ID and western UT by late afternoon. Guidance continues to show a strong signal for 20-25 mph winds through much of the afternoon, and single-digit RH values should support widespread critical fire weather conditions. ...Southern California into the San Joaquin Valley... A strong onshore pressure gradient will support increasing downslope winds on the leeward side/eastern slopes of the coastal ranges across southern California this afternoon. Relative humidities values falling into the teens within the downslope regime, coupled with dry grasses, will support a fire weather concern. ...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 1137 AM CDT Fri Jun 20 2025 Valid 201700Z - 211200Z ...CRITICAL FIRE WEATHER AREA FOR FOUR CORNERS AND GREAT BASIN... No changes are needed to the current D1 Fire Weather Outlook. Morning satellite analysis shows mostly sunny skies across the Critical area, with relative humidity ranging from 15-20 percent and winds gusting 20-30 mph. HREF guidance continues to indicate that several hours of Critical conditions are likely from the Great Basin to the Four Corners and into portions of the High Plains through this afternoon. See previous discussion below for more information. ..Thornton.. 06/20/2025 .PREV DISCUSSION... /ISSUED 0132 AM CDT Fri Jun 20 2025/ ...Synopsis... Widespread critical fire weather conditions are expected today across parts of the Greater Four Corners region and the Great Basin. Early-morning water vapor imagery shows a dominant upper ridge over the central CONUS with shortwave troughing over the western Great Basin and northeastern Pacific. The Great Basin shortwave is forecast to move into the northern High Plains through the afternoon, which will facilitate surface low development across eastern WY by late afternoon. Strengthening low-level winds in response to the deepening low will promote a widespread swath of 20-30 mph winds within a very dry air mass and across a region with receptive fuels. ...Four Corners into the High Plains... The axis of the mid-level jet associated with the leading shortwave is forecast to reside from southeast UT into southern WY by peak heating. This will maximize the potential for 20+ mph winds at the surface, and will likely support wind gusts between 30-45 mph. RH values in the single digits to low teens coupled with antecedent dry fuels (active fires were recently noted across southern UT in GOES IR imagery) will support widespread and prolonged critical conditions with periods of extremely critical wind speeds possible - especially across south-central WY. Elevated to critical fire weather conditions will likely extend well to the northeast into the central High Plains, and possibly as far east and western South Dakota behind an eastward surging dry line. However, fuel conditions generally improve with eastward extent due to recent rainfall. Fire risk highlights have been expanded northeast to account for the strong wind/RH signal, but Critical highlights were focused across areas with dry, receptive fuels. ...Nevada into adjacent portions of Idaho and Utah... Southwesterly flow over the southern to central Sierra Nevada will induce strong downslope flow into western and central NV, spreading into southeast ID and western UT by late afternoon. Guidance continues to show a strong signal for 20-25 mph winds through much of the afternoon, and single-digit RH values should support widespread critical fire weather conditions. ...Southern California into the San Joaquin Valley... A strong onshore pressure gradient will support increasing downslope winds on the leeward side/eastern slopes of the coastal ranges across southern California this afternoon. Relative humidities values falling into the teens within the downslope regime, coupled with dry grasses, will support a fire weather concern. ...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 1137 AM CDT Fri Jun 20 2025 Valid 201700Z - 211200Z ...CRITICAL FIRE WEATHER AREA FOR FOUR CORNERS AND GREAT BASIN... No changes are needed to the current D1 Fire Weather Outlook. Morning satellite analysis shows mostly sunny skies across the Critical area, with relative humidity ranging from 15-20 percent and winds gusting 20-30 mph. HREF guidance continues to indicate that several hours of Critical conditions are likely from the Great Basin to the Four Corners and into portions of the High Plains through this afternoon. See previous discussion below for more information. ..Thornton.. 06/20/2025 .PREV DISCUSSION... /ISSUED 0132 AM CDT Fri Jun 20 2025/ ...Synopsis... Widespread critical fire weather conditions are expected today across parts of the Greater Four Corners region and the Great Basin. Early-morning water vapor imagery shows a dominant upper ridge over the central CONUS with shortwave troughing over the western Great Basin and northeastern Pacific. The Great Basin shortwave is forecast to move into the northern High Plains through the afternoon, which will facilitate surface low development across eastern WY by late afternoon. Strengthening low-level winds in response to the deepening low will promote a widespread swath of 20-30 mph winds within a very dry air mass and across a region with receptive fuels. ...Four Corners into the High Plains... The axis of the mid-level jet associated with the leading shortwave is forecast to reside from southeast UT into southern WY by peak heating. This will maximize the potential for 20+ mph winds at the surface, and will likely support wind gusts between 30-45 mph. RH values in the single digits to low teens coupled with antecedent dry fuels (active fires were recently noted across southern UT in GOES IR imagery) will support widespread and prolonged critical conditions with periods of extremely critical wind speeds possible - especially across south-central WY. Elevated to critical fire weather conditions will likely extend well to the northeast into the central High Plains, and possibly as far east and western South Dakota behind an eastward surging dry line. However, fuel conditions generally improve with eastward extent due to recent rainfall. Fire risk highlights have been expanded northeast to account for the strong wind/RH signal, but Critical highlights were focused across areas with dry, receptive fuels. ...Nevada into adjacent portions of Idaho and Utah... Southwesterly flow over the southern to central Sierra Nevada will induce strong downslope flow into western and central NV, spreading into southeast ID and western UT by late afternoon. Guidance continues to show a strong signal for 20-25 mph winds through much of the afternoon, and single-digit RH values should support widespread critical fire weather conditions. ...Southern California into the San Joaquin Valley... A strong onshore pressure gradient will support increasing downslope winds on the leeward side/eastern slopes of the coastal ranges across southern California this afternoon. Relative humidities values falling into the teens within the downslope regime, coupled with dry grasses, will support a fire weather concern. ...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 1137 AM CDT Fri Jun 20 2025 Valid 201700Z - 211200Z ...CRITICAL FIRE WEATHER AREA FOR FOUR CORNERS AND GREAT BASIN... No changes are needed to the current D1 Fire Weather Outlook. Morning satellite analysis shows mostly sunny skies across the Critical area, with relative humidity ranging from 15-20 percent and winds gusting 20-30 mph. HREF guidance continues to indicate that several hours of Critical conditions are likely from the Great Basin to the Four Corners and into portions of the High Plains through this afternoon. See previous discussion below for more information. ..Thornton.. 06/20/2025 .PREV DISCUSSION... /ISSUED 0132 AM CDT Fri Jun 20 2025/ ...Synopsis... Widespread critical fire weather conditions are expected today across parts of the Greater Four Corners region and the Great Basin. Early-morning water vapor imagery shows a dominant upper ridge over the central CONUS with shortwave troughing over the western Great Basin and northeastern Pacific. The Great Basin shortwave is forecast to move into the northern High Plains through the afternoon, which will facilitate surface low development across eastern WY by late afternoon. Strengthening low-level winds in response to the deepening low will promote a widespread swath of 20-30 mph winds within a very dry air mass and across a region with receptive fuels. ...Four Corners into the High Plains... The axis of the mid-level jet associated with the leading shortwave is forecast to reside from southeast UT into southern WY by peak heating. This will maximize the potential for 20+ mph winds at the surface, and will likely support wind gusts between 30-45 mph. RH values in the single digits to low teens coupled with antecedent dry fuels (active fires were recently noted across southern UT in GOES IR imagery) will support widespread and prolonged critical conditions with periods of extremely critical wind speeds possible - especially across south-central WY. Elevated to critical fire weather conditions will likely extend well to the northeast into the central High Plains, and possibly as far east and western South Dakota behind an eastward surging dry line. However, fuel conditions generally improve with eastward extent due to recent rainfall. Fire risk highlights have been expanded northeast to account for the strong wind/RH signal, but Critical highlights were focused across areas with dry, receptive fuels. ...Nevada into adjacent portions of Idaho and Utah... Southwesterly flow over the southern to central Sierra Nevada will induce strong downslope flow into western and central NV, spreading into southeast ID and western UT by late afternoon. Guidance continues to show a strong signal for 20-25 mph winds through much of the afternoon, and single-digit RH values should support widespread critical fire weather conditions. ...Southern California into the San Joaquin Valley... A strong onshore pressure gradient will support increasing downslope winds on the leeward side/eastern slopes of the coastal ranges across southern California this afternoon. Relative humidities values falling into the teens within the downslope regime, coupled with dry grasses, will support a fire weather concern. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1125 AM CDT Fri Jun 20 2025 Valid 201630Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT FROM EASTERN MONTANA...ACROSS MUCH OF NORTH DAKOTA...INTO NORTHERN MINNESOTA.... ...SUMMARY... Severe thunderstorms are likely this afternoon into tonight from far eastern Montana eastward across the northern Plains and into the upper Mississippi Valley. Tornadoes, winds greater than 75 mph, and hailstones greater than 2 inches in diameter will all be possible. ...Eastern MT/ND/MN/WI/Upper MI... No significant changes have been made to the ongoing outlook. Water vapor imagery shows a deepening upper trough over the northern Rockies, with a pronounced shortwave trough entering western MT. Strong lift associated with this trough will overspread eastern MT and western ND this evening, leading to the development of scattered supercell thunderstorms in a region of backed/upslope flow to the north of the surface low. These storms will track eastward through the evening across ND and eventually grow upscale. Very large hail and tornadoes will be possible for the first few hours of this scenario, with an increasing risk of damaging winds with time. An upgrade to MDT risk was considered, but will maintain ENH due to diversity of solutions in various model guidance and uncertainty of corridor of greatest threat. Farther east, an increasingly strong nocturnal low-level jet will help rapid thunderstorm development from eastern ND into MN this evening. Parameters in this area are very favorable for supercells capable of all severe hazards, including very large hail and tornadoes. However, late initiation of storms, warm temperatures in the 850-700mb layer, and rapid storm interactions lend uncertainty regarding the evolution of this activity. Some 12z guidance suggests one or more bowing structures evolve out of this cluster, tracking eastward overnight across MN into WI and Upper MI. ...Western MT... As the aforementioned shortwave trough moves eastward, scattered thunderstorms are forecast to develop off the mountains of western MT. Widespread cloud cover will limit heating/destabilization, but favorable deep-layer shear may support a few rotating thunderstorms. Hail could occur in the strongest storms. ...Southeast Lower MI... A convectively-aided shortwave trough is moving across Lake MI and western Lower MI. This feature may encourage the development of scattered thunderstorms this afternoon over southeast Lower MI and western Lake Erie. These storms could produce gusty winds and hail. ...High Plains... Full sunshine will lead to steep low-level lapse rates and moderate CAPE values this afternoon from southwest NE into eastern NM. Deep mixing will likely result in widely scattered afternoon and evening thunderstorms. This high-based activity will be capable of locally damaging wind gusts. ..Hart/Squitieri.. 06/20/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1125 AM CDT Fri Jun 20 2025 Valid 201630Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT FROM EASTERN MONTANA...ACROSS MUCH OF NORTH DAKOTA...INTO NORTHERN MINNESOTA.... ...SUMMARY... Severe thunderstorms are likely this afternoon into tonight from far eastern Montana eastward across the northern Plains and into the upper Mississippi Valley. Tornadoes, winds greater than 75 mph, and hailstones greater than 2 inches in diameter will all be possible. ...Eastern MT/ND/MN/WI/Upper MI... No significant changes have been made to the ongoing outlook. Water vapor imagery shows a deepening upper trough over the northern Rockies, with a pronounced shortwave trough entering western MT. Strong lift associated with this trough will overspread eastern MT and western ND this evening, leading to the development of scattered supercell thunderstorms in a region of backed/upslope flow to the north of the surface low. These storms will track eastward through the evening across ND and eventually grow upscale. Very large hail and tornadoes will be possible for the first few hours of this scenario, with an increasing risk of damaging winds with time. An upgrade to MDT risk was considered, but will maintain ENH due to diversity of solutions in various model guidance and uncertainty of corridor of greatest threat. Farther east, an increasingly strong nocturnal low-level jet will help rapid thunderstorm development from eastern ND into MN this evening. Parameters in this area are very favorable for supercells capable of all severe hazards, including very large hail and tornadoes. However, late initiation of storms, warm temperatures in the 850-700mb layer, and rapid storm interactions lend uncertainty regarding the evolution of this activity. Some 12z guidance suggests one or more bowing structures evolve out of this cluster, tracking eastward overnight across MN into WI and Upper MI. ...Western MT... As the aforementioned shortwave trough moves eastward, scattered thunderstorms are forecast to develop off the mountains of western MT. Widespread cloud cover will limit heating/destabilization, but favorable deep-layer shear may support a few rotating thunderstorms. Hail could occur in the strongest storms. ...Southeast Lower MI... A convectively-aided shortwave trough is moving across Lake MI and western Lower MI. This feature may encourage the development of scattered thunderstorms this afternoon over southeast Lower MI and western Lake Erie. These storms could produce gusty winds and hail. ...High Plains... Full sunshine will lead to steep low-level lapse rates and moderate CAPE values this afternoon from southwest NE into eastern NM. Deep mixing will likely result in widely scattered afternoon and evening thunderstorms. This high-based activity will be capable of locally damaging wind gusts. ..Hart/Squitieri.. 06/20/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1125 AM CDT Fri Jun 20 2025 Valid 201630Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT FROM EASTERN MONTANA...ACROSS MUCH OF NORTH DAKOTA...INTO NORTHERN MINNESOTA.... ...SUMMARY... Severe thunderstorms are likely this afternoon into tonight from far eastern Montana eastward across the northern Plains and into the upper Mississippi Valley. Tornadoes, winds greater than 75 mph, and hailstones greater than 2 inches in diameter will all be possible. ...Eastern MT/ND/MN/WI/Upper MI... No significant changes have been made to the ongoing outlook. Water vapor imagery shows a deepening upper trough over the northern Rockies, with a pronounced shortwave trough entering western MT. Strong lift associated with this trough will overspread eastern MT and western ND this evening, leading to the development of scattered supercell thunderstorms in a region of backed/upslope flow to the north of the surface low. These storms will track eastward through the evening across ND and eventually grow upscale. Very large hail and tornadoes will be possible for the first few hours of this scenario, with an increasing risk of damaging winds with time. An upgrade to MDT risk was considered, but will maintain ENH due to diversity of solutions in various model guidance and uncertainty of corridor of greatest threat. Farther east, an increasingly strong nocturnal low-level jet will help rapid thunderstorm development from eastern ND into MN this evening. Parameters in this area are very favorable for supercells capable of all severe hazards, including very large hail and tornadoes. However, late initiation of storms, warm temperatures in the 850-700mb layer, and rapid storm interactions lend uncertainty regarding the evolution of this activity. Some 12z guidance suggests one or more bowing structures evolve out of this cluster, tracking eastward overnight across MN into WI and Upper MI. ...Western MT... As the aforementioned shortwave trough moves eastward, scattered thunderstorms are forecast to develop off the mountains of western MT. Widespread cloud cover will limit heating/destabilization, but favorable deep-layer shear may support a few rotating thunderstorms. Hail could occur in the strongest storms. ...Southeast Lower MI... A convectively-aided shortwave trough is moving across Lake MI and western Lower MI. This feature may encourage the development of scattered thunderstorms this afternoon over southeast Lower MI and western Lake Erie. These storms could produce gusty winds and hail. ...High Plains... Full sunshine will lead to steep low-level lapse rates and moderate CAPE values this afternoon from southwest NE into eastern NM. Deep mixing will likely result in widely scattered afternoon and evening thunderstorms. This high-based activity will be capable of locally damaging wind gusts. ..Hart/Squitieri.. 06/20/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1125 AM CDT Fri Jun 20 2025 Valid 201630Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT FROM EASTERN MONTANA...ACROSS MUCH OF NORTH DAKOTA...INTO NORTHERN MINNESOTA.... ...SUMMARY... Severe thunderstorms are likely this afternoon into tonight from far eastern Montana eastward across the northern Plains and into the upper Mississippi Valley. Tornadoes, winds greater than 75 mph, and hailstones greater than 2 inches in diameter will all be possible. ...Eastern MT/ND/MN/WI/Upper MI... No significant changes have been made to the ongoing outlook. Water vapor imagery shows a deepening upper trough over the northern Rockies, with a pronounced shortwave trough entering western MT. Strong lift associated with this trough will overspread eastern MT and western ND this evening, leading to the development of scattered supercell thunderstorms in a region of backed/upslope flow to the north of the surface low. These storms will track eastward through the evening across ND and eventually grow upscale. Very large hail and tornadoes will be possible for the first few hours of this scenario, with an increasing risk of damaging winds with time. An upgrade to MDT risk was considered, but will maintain ENH due to diversity of solutions in various model guidance and uncertainty of corridor of greatest threat. Farther east, an increasingly strong nocturnal low-level jet will help rapid thunderstorm development from eastern ND into MN this evening. Parameters in this area are very favorable for supercells capable of all severe hazards, including very large hail and tornadoes. However, late initiation of storms, warm temperatures in the 850-700mb layer, and rapid storm interactions lend uncertainty regarding the evolution of this activity. Some 12z guidance suggests one or more bowing structures evolve out of this cluster, tracking eastward overnight across MN into WI and Upper MI. ...Western MT... As the aforementioned shortwave trough moves eastward, scattered thunderstorms are forecast to develop off the mountains of western MT. Widespread cloud cover will limit heating/destabilization, but favorable deep-layer shear may support a few rotating thunderstorms. Hail could occur in the strongest storms. ...Southeast Lower MI... A convectively-aided shortwave trough is moving across Lake MI and western Lower MI. This feature may encourage the development of scattered thunderstorms this afternoon over southeast Lower MI and western Lake Erie. These storms could produce gusty winds and hail. ...High Plains... Full sunshine will lead to steep low-level lapse rates and moderate CAPE values this afternoon from southwest NE into eastern NM. Deep mixing will likely result in widely scattered afternoon and evening thunderstorms. This high-based activity will be capable of locally damaging wind gusts. ..Hart/Squitieri.. 06/20/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1125 AM CDT Fri Jun 20 2025 Valid 201630Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT FROM EASTERN MONTANA...ACROSS MUCH OF NORTH DAKOTA...INTO NORTHERN MINNESOTA.... ...SUMMARY... Severe thunderstorms are likely this afternoon into tonight from far eastern Montana eastward across the northern Plains and into the upper Mississippi Valley. Tornadoes, winds greater than 75 mph, and hailstones greater than 2 inches in diameter will all be possible. ...Eastern MT/ND/MN/WI/Upper MI... No significant changes have been made to the ongoing outlook. Water vapor imagery shows a deepening upper trough over the northern Rockies, with a pronounced shortwave trough entering western MT. Strong lift associated with this trough will overspread eastern MT and western ND this evening, leading to the development of scattered supercell thunderstorms in a region of backed/upslope flow to the north of the surface low. These storms will track eastward through the evening across ND and eventually grow upscale. Very large hail and tornadoes will be possible for the first few hours of this scenario, with an increasing risk of damaging winds with time. An upgrade to MDT risk was considered, but will maintain ENH due to diversity of solutions in various model guidance and uncertainty of corridor of greatest threat. Farther east, an increasingly strong nocturnal low-level jet will help rapid thunderstorm development from eastern ND into MN this evening. Parameters in this area are very favorable for supercells capable of all severe hazards, including very large hail and tornadoes. However, late initiation of storms, warm temperatures in the 850-700mb layer, and rapid storm interactions lend uncertainty regarding the evolution of this activity. Some 12z guidance suggests one or more bowing structures evolve out of this cluster, tracking eastward overnight across MN into WI and Upper MI. ...Western MT... As the aforementioned shortwave trough moves eastward, scattered thunderstorms are forecast to develop off the mountains of western MT. Widespread cloud cover will limit heating/destabilization, but favorable deep-layer shear may support a few rotating thunderstorms. Hail could occur in the strongest storms. ...Southeast Lower MI... A convectively-aided shortwave trough is moving across Lake MI and western Lower MI. This feature may encourage the development of scattered thunderstorms this afternoon over southeast Lower MI and western Lake Erie. These storms could produce gusty winds and hail. ...High Plains... Full sunshine will lead to steep low-level lapse rates and moderate CAPE values this afternoon from southwest NE into eastern NM. Deep mixing will likely result in widely scattered afternoon and evening thunderstorms. This high-based activity will be capable of locally damaging wind gusts. ..Hart/Squitieri.. 06/20/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1125 AM CDT Fri Jun 20 2025 Valid 201630Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT FROM EASTERN MONTANA...ACROSS MUCH OF NORTH DAKOTA...INTO NORTHERN MINNESOTA.... ...SUMMARY... Severe thunderstorms are likely this afternoon into tonight from far eastern Montana eastward across the northern Plains and into the upper Mississippi Valley. Tornadoes, winds greater than 75 mph, and hailstones greater than 2 inches in diameter will all be possible. ...Eastern MT/ND/MN/WI/Upper MI... No significant changes have been made to the ongoing outlook. Water vapor imagery shows a deepening upper trough over the northern Rockies, with a pronounced shortwave trough entering western MT. Strong lift associated with this trough will overspread eastern MT and western ND this evening, leading to the development of scattered supercell thunderstorms in a region of backed/upslope flow to the north of the surface low. These storms will track eastward through the evening across ND and eventually grow upscale. Very large hail and tornadoes will be possible for the first few hours of this scenario, with an increasing risk of damaging winds with time. An upgrade to MDT risk was considered, but will maintain ENH due to diversity of solutions in various model guidance and uncertainty of corridor of greatest threat. Farther east, an increasingly strong nocturnal low-level jet will help rapid thunderstorm development from eastern ND into MN this evening. Parameters in this area are very favorable for supercells capable of all severe hazards, including very large hail and tornadoes. However, late initiation of storms, warm temperatures in the 850-700mb layer, and rapid storm interactions lend uncertainty regarding the evolution of this activity. Some 12z guidance suggests one or more bowing structures evolve out of this cluster, tracking eastward overnight across MN into WI and Upper MI. ...Western MT... As the aforementioned shortwave trough moves eastward, scattered thunderstorms are forecast to develop off the mountains of western MT. Widespread cloud cover will limit heating/destabilization, but favorable deep-layer shear may support a few rotating thunderstorms. Hail could occur in the strongest storms. ...Southeast Lower MI... A convectively-aided shortwave trough is moving across Lake MI and western Lower MI. This feature may encourage the development of scattered thunderstorms this afternoon over southeast Lower MI and western Lake Erie. These storms could produce gusty winds and hail. ...High Plains... Full sunshine will lead to steep low-level lapse rates and moderate CAPE values this afternoon from southwest NE into eastern NM. Deep mixing will likely result in widely scattered afternoon and evening thunderstorms. This high-based activity will be capable of locally damaging wind gusts. ..Hart/Squitieri.. 06/20/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1125 AM CDT Fri Jun 20 2025 Valid 201630Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT FROM EASTERN MONTANA...ACROSS MUCH OF NORTH DAKOTA...INTO NORTHERN MINNESOTA.... ...SUMMARY... Severe thunderstorms are likely this afternoon into tonight from far eastern Montana eastward across the northern Plains and into the upper Mississippi Valley. Tornadoes, winds greater than 75 mph, and hailstones greater than 2 inches in diameter will all be possible. ...Eastern MT/ND/MN/WI/Upper MI... No significant changes have been made to the ongoing outlook. Water vapor imagery shows a deepening upper trough over the northern Rockies, with a pronounced shortwave trough entering western MT. Strong lift associated with this trough will overspread eastern MT and western ND this evening, leading to the development of scattered supercell thunderstorms in a region of backed/upslope flow to the north of the surface low. These storms will track eastward through the evening across ND and eventually grow upscale. Very large hail and tornadoes will be possible for the first few hours of this scenario, with an increasing risk of damaging winds with time. An upgrade to MDT risk was considered, but will maintain ENH due to diversity of solutions in various model guidance and uncertainty of corridor of greatest threat. Farther east, an increasingly strong nocturnal low-level jet will help rapid thunderstorm development from eastern ND into MN this evening. Parameters in this area are very favorable for supercells capable of all severe hazards, including very large hail and tornadoes. However, late initiation of storms, warm temperatures in the 850-700mb layer, and rapid storm interactions lend uncertainty regarding the evolution of this activity. Some 12z guidance suggests one or more bowing structures evolve out of this cluster, tracking eastward overnight across MN into WI and Upper MI. ...Western MT... As the aforementioned shortwave trough moves eastward, scattered thunderstorms are forecast to develop off the mountains of western MT. Widespread cloud cover will limit heating/destabilization, but favorable deep-layer shear may support a few rotating thunderstorms. Hail could occur in the strongest storms. ...Southeast Lower MI... A convectively-aided shortwave trough is moving across Lake MI and western Lower MI. This feature may encourage the development of scattered thunderstorms this afternoon over southeast Lower MI and western Lake Erie. These storms could produce gusty winds and hail. ...High Plains... Full sunshine will lead to steep low-level lapse rates and moderate CAPE values this afternoon from southwest NE into eastern NM. Deep mixing will likely result in widely scattered afternoon and evening thunderstorms. This high-based activity will be capable of locally damaging wind gusts. ..Hart/Squitieri.. 06/20/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1125 AM CDT Fri Jun 20 2025 Valid 201630Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT FROM EASTERN MONTANA...ACROSS MUCH OF NORTH DAKOTA...INTO NORTHERN MINNESOTA.... ...SUMMARY... Severe thunderstorms are likely this afternoon into tonight from far eastern Montana eastward across the northern Plains and into the upper Mississippi Valley. Tornadoes, winds greater than 75 mph, and hailstones greater than 2 inches in diameter will all be possible. ...Eastern MT/ND/MN/WI/Upper MI... No significant changes have been made to the ongoing outlook. Water vapor imagery shows a deepening upper trough over the northern Rockies, with a pronounced shortwave trough entering western MT. Strong lift associated with this trough will overspread eastern MT and western ND this evening, leading to the development of scattered supercell thunderstorms in a region of backed/upslope flow to the north of the surface low. These storms will track eastward through the evening across ND and eventually grow upscale. Very large hail and tornadoes will be possible for the first few hours of this scenario, with an increasing risk of damaging winds with time. An upgrade to MDT risk was considered, but will maintain ENH due to diversity of solutions in various model guidance and uncertainty of corridor of greatest threat. Farther east, an increasingly strong nocturnal low-level jet will help rapid thunderstorm development from eastern ND into MN this evening. Parameters in this area are very favorable for supercells capable of all severe hazards, including very large hail and tornadoes. However, late initiation of storms, warm temperatures in the 850-700mb layer, and rapid storm interactions lend uncertainty regarding the evolution of this activity. Some 12z guidance suggests one or more bowing structures evolve out of this cluster, tracking eastward overnight across MN into WI and Upper MI. ...Western MT... As the aforementioned shortwave trough moves eastward, scattered thunderstorms are forecast to develop off the mountains of western MT. Widespread cloud cover will limit heating/destabilization, but favorable deep-layer shear may support a few rotating thunderstorms. Hail could occur in the strongest storms. ...Southeast Lower MI... A convectively-aided shortwave trough is moving across Lake MI and western Lower MI. This feature may encourage the development of scattered thunderstorms this afternoon over southeast Lower MI and western Lake Erie. These storms could produce gusty winds and hail. ...High Plains... Full sunshine will lead to steep low-level lapse rates and moderate CAPE values this afternoon from southwest NE into eastern NM. Deep mixing will likely result in widely scattered afternoon and evening thunderstorms. This high-based activity will be capable of locally damaging wind gusts. ..Hart/Squitieri.. 06/20/2025 Read more