Aggregator

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0128 AM CDT Tue Jul 22 2025 Valid 221200Z - 231200Z ...Synopsis... While mid-level winds will steadily weaken across the Great Basin today, enough flow across the Sierra and strong heating in Nevada will promote a weak surface trough in northern Nevada. This feature will drive downslope winds into parts of southern and central Nevada. Winds around 15 to perhaps 20 mph will occur in a confined zone. RH will fall to 10-15% by the afternoon. Local, marginally critical conditions may occur very briefly as well. A few hours of elevated fire weather is expected. ..Wendt.. 07/22/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0128 AM CDT Tue Jul 22 2025 Valid 221200Z - 231200Z ...Synopsis... While mid-level winds will steadily weaken across the Great Basin today, enough flow across the Sierra and strong heating in Nevada will promote a weak surface trough in northern Nevada. This feature will drive downslope winds into parts of southern and central Nevada. Winds around 15 to perhaps 20 mph will occur in a confined zone. RH will fall to 10-15% by the afternoon. Local, marginally critical conditions may occur very briefly as well. A few hours of elevated fire weather is expected. ..Wendt.. 07/22/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0128 AM CDT Tue Jul 22 2025 Valid 221200Z - 231200Z ...Synopsis... While mid-level winds will steadily weaken across the Great Basin today, enough flow across the Sierra and strong heating in Nevada will promote a weak surface trough in northern Nevada. This feature will drive downslope winds into parts of southern and central Nevada. Winds around 15 to perhaps 20 mph will occur in a confined zone. RH will fall to 10-15% by the afternoon. Local, marginally critical conditions may occur very briefly as well. A few hours of elevated fire weather is expected. ..Wendt.. 07/22/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0128 AM CDT Tue Jul 22 2025 Valid 221200Z - 231200Z ...Synopsis... While mid-level winds will steadily weaken across the Great Basin today, enough flow across the Sierra and strong heating in Nevada will promote a weak surface trough in northern Nevada. This feature will drive downslope winds into parts of southern and central Nevada. Winds around 15 to perhaps 20 mph will occur in a confined zone. RH will fall to 10-15% by the afternoon. Local, marginally critical conditions may occur very briefly as well. A few hours of elevated fire weather is expected. ..Wendt.. 07/22/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0128 AM CDT Tue Jul 22 2025 Valid 221200Z - 231200Z ...Synopsis... While mid-level winds will steadily weaken across the Great Basin today, enough flow across the Sierra and strong heating in Nevada will promote a weak surface trough in northern Nevada. This feature will drive downslope winds into parts of southern and central Nevada. Winds around 15 to perhaps 20 mph will occur in a confined zone. RH will fall to 10-15% by the afternoon. Local, marginally critical conditions may occur very briefly as well. A few hours of elevated fire weather is expected. ..Wendt.. 07/22/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1149 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WEDNESDAY INTO WEDNESDAY NIGHT ACROSS PARTS OF CENTRAL AND NORTHEASTERN NEBRASKA...SOUTHEASTERN SOUTH DAKOTA...NORTHEASTERN IOWA...SOUTHERN MINNESOTA...NORTHERN WISCONSIN...UPPER MICHIGAN... ...SUMMARY... Organizing clusters of storms posing a risk for severe wind are possible across parts of the middle Missouri Valley and Upper Midwest into adjacent portions of the Great Lakes region Wednesday through Wednesday night. ...Discussion... Models continue to indicate further suppression of the northeastern Pacific mid-level ridging, with flow becoming more zonal and progressive across the British Columbia coast into the Canadian Prairies during this period. Downstream, it still appears that mid/upper flow will continue to intensify in a belt across Ontario through Quebec, between a significant trough and cyclone slowly migrating eastward across Hudson Bay and prominent ridging initially centered over the Ohio Valley. A cold front trailing the cyclone is still likely to advance more rapidly southward across the Great Plains, to the lee of the Rockies, than across the Upper Midwest and adjacent Great Lakes region. This general evolution has been forecast for several days, but spread has been evident within and among the various model output concerning the synoptic and, particularly, sub-synoptic developments, which persists in latest model runs. Among the details which remain characterized by sizable spread, the cold frontal progression through the Great Plains/mid Missouri Valley vicinity, the strength of a short wave perturbation progressing out of the Pacific Northwest through the central Canadian/U.S. border vicinity, and weak mid/upper perturbations migrating around the southern and northwestern periphery of the interior U.S. ridge, across the Gulf coast and southern Great Plains toward upper Mississippi Valley. These and other smaller-scale perturbations, with low predictability at this time frame, will considerably impact the convective potential for Wednesday through Wednesday night. ...Mid Missouri Valley into Upper Midwest/Great Lakes... While it still appears that the southern fringe of the stronger mid/upper westerlies will not extend south of a corridor from southeastern Minnesota through northern Wisconsin and Upper Michigan, models now generally indicate a belt of moderate south-southwest flow (20-40 kt in the 850-700 mb layer) in the lower/mid-levels will develop across the central Great Plains into the Upper Midwest, ahead of the weak perturbation migrating around the western periphery of the mid-level ridge. Beneath modestly steep lapse rates, but with generally warm profiles, it now appears increasingly probable that seasonably high boundary-layer moisture content, supportive of large mixed-layer CAPE, will extend along the frontal zone from the Upper Midwest/Great Lakes as far southwest as central/northeastern Nebraska by late afternoon. Coupled with the strength of the lower/mid-tropospheric flow, it appears probable that this environment will become supportive of one or two organizing thunderstorm clusters with potential to produce swaths of strong to severe wind gusts. However, based on late model output, including available convection allowing guidance, the potential evolution Wednesday through Wednesday night remains rather uncertain at this time. ...Northern Rockies into Front Range... In the presence of steep lapse rates, moistening easterly to southeasterly near-surface flow, beneath modest westerly flow aloft, may contribute to sufficient destabilization and shear to support widely scattered strong to severe storms. This may include evolving supercells near/just east of the higher terrain late Wednesday afternoon and evening. ..Kerr.. 07/22/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1149 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WEDNESDAY INTO WEDNESDAY NIGHT ACROSS PARTS OF CENTRAL AND NORTHEASTERN NEBRASKA...SOUTHEASTERN SOUTH DAKOTA...NORTHEASTERN IOWA...SOUTHERN MINNESOTA...NORTHERN WISCONSIN...UPPER MICHIGAN... ...SUMMARY... Organizing clusters of storms posing a risk for severe wind are possible across parts of the middle Missouri Valley and Upper Midwest into adjacent portions of the Great Lakes region Wednesday through Wednesday night. ...Discussion... Models continue to indicate further suppression of the northeastern Pacific mid-level ridging, with flow becoming more zonal and progressive across the British Columbia coast into the Canadian Prairies during this period. Downstream, it still appears that mid/upper flow will continue to intensify in a belt across Ontario through Quebec, between a significant trough and cyclone slowly migrating eastward across Hudson Bay and prominent ridging initially centered over the Ohio Valley. A cold front trailing the cyclone is still likely to advance more rapidly southward across the Great Plains, to the lee of the Rockies, than across the Upper Midwest and adjacent Great Lakes region. This general evolution has been forecast for several days, but spread has been evident within and among the various model output concerning the synoptic and, particularly, sub-synoptic developments, which persists in latest model runs. Among the details which remain characterized by sizable spread, the cold frontal progression through the Great Plains/mid Missouri Valley vicinity, the strength of a short wave perturbation progressing out of the Pacific Northwest through the central Canadian/U.S. border vicinity, and weak mid/upper perturbations migrating around the southern and northwestern periphery of the interior U.S. ridge, across the Gulf coast and southern Great Plains toward upper Mississippi Valley. These and other smaller-scale perturbations, with low predictability at this time frame, will considerably impact the convective potential for Wednesday through Wednesday night. ...Mid Missouri Valley into Upper Midwest/Great Lakes... While it still appears that the southern fringe of the stronger mid/upper westerlies will not extend south of a corridor from southeastern Minnesota through northern Wisconsin and Upper Michigan, models now generally indicate a belt of moderate south-southwest flow (20-40 kt in the 850-700 mb layer) in the lower/mid-levels will develop across the central Great Plains into the Upper Midwest, ahead of the weak perturbation migrating around the western periphery of the mid-level ridge. Beneath modestly steep lapse rates, but with generally warm profiles, it now appears increasingly probable that seasonably high boundary-layer moisture content, supportive of large mixed-layer CAPE, will extend along the frontal zone from the Upper Midwest/Great Lakes as far southwest as central/northeastern Nebraska by late afternoon. Coupled with the strength of the lower/mid-tropospheric flow, it appears probable that this environment will become supportive of one or two organizing thunderstorm clusters with potential to produce swaths of strong to severe wind gusts. However, based on late model output, including available convection allowing guidance, the potential evolution Wednesday through Wednesday night remains rather uncertain at this time. ...Northern Rockies into Front Range... In the presence of steep lapse rates, moistening easterly to southeasterly near-surface flow, beneath modest westerly flow aloft, may contribute to sufficient destabilization and shear to support widely scattered strong to severe storms. This may include evolving supercells near/just east of the higher terrain late Wednesday afternoon and evening. ..Kerr.. 07/22/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1149 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WEDNESDAY INTO WEDNESDAY NIGHT ACROSS PARTS OF CENTRAL AND NORTHEASTERN NEBRASKA...SOUTHEASTERN SOUTH DAKOTA...NORTHEASTERN IOWA...SOUTHERN MINNESOTA...NORTHERN WISCONSIN...UPPER MICHIGAN... ...SUMMARY... Organizing clusters of storms posing a risk for severe wind are possible across parts of the middle Missouri Valley and Upper Midwest into adjacent portions of the Great Lakes region Wednesday through Wednesday night. ...Discussion... Models continue to indicate further suppression of the northeastern Pacific mid-level ridging, with flow becoming more zonal and progressive across the British Columbia coast into the Canadian Prairies during this period. Downstream, it still appears that mid/upper flow will continue to intensify in a belt across Ontario through Quebec, between a significant trough and cyclone slowly migrating eastward across Hudson Bay and prominent ridging initially centered over the Ohio Valley. A cold front trailing the cyclone is still likely to advance more rapidly southward across the Great Plains, to the lee of the Rockies, than across the Upper Midwest and adjacent Great Lakes region. This general evolution has been forecast for several days, but spread has been evident within and among the various model output concerning the synoptic and, particularly, sub-synoptic developments, which persists in latest model runs. Among the details which remain characterized by sizable spread, the cold frontal progression through the Great Plains/mid Missouri Valley vicinity, the strength of a short wave perturbation progressing out of the Pacific Northwest through the central Canadian/U.S. border vicinity, and weak mid/upper perturbations migrating around the southern and northwestern periphery of the interior U.S. ridge, across the Gulf coast and southern Great Plains toward upper Mississippi Valley. These and other smaller-scale perturbations, with low predictability at this time frame, will considerably impact the convective potential for Wednesday through Wednesday night. ...Mid Missouri Valley into Upper Midwest/Great Lakes... While it still appears that the southern fringe of the stronger mid/upper westerlies will not extend south of a corridor from southeastern Minnesota through northern Wisconsin and Upper Michigan, models now generally indicate a belt of moderate south-southwest flow (20-40 kt in the 850-700 mb layer) in the lower/mid-levels will develop across the central Great Plains into the Upper Midwest, ahead of the weak perturbation migrating around the western periphery of the mid-level ridge. Beneath modestly steep lapse rates, but with generally warm profiles, it now appears increasingly probable that seasonably high boundary-layer moisture content, supportive of large mixed-layer CAPE, will extend along the frontal zone from the Upper Midwest/Great Lakes as far southwest as central/northeastern Nebraska by late afternoon. Coupled with the strength of the lower/mid-tropospheric flow, it appears probable that this environment will become supportive of one or two organizing thunderstorm clusters with potential to produce swaths of strong to severe wind gusts. However, based on late model output, including available convection allowing guidance, the potential evolution Wednesday through Wednesday night remains rather uncertain at this time. ...Northern Rockies into Front Range... In the presence of steep lapse rates, moistening easterly to southeasterly near-surface flow, beneath modest westerly flow aloft, may contribute to sufficient destabilization and shear to support widely scattered strong to severe storms. This may include evolving supercells near/just east of the higher terrain late Wednesday afternoon and evening. ..Kerr.. 07/22/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1149 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WEDNESDAY INTO WEDNESDAY NIGHT ACROSS PARTS OF CENTRAL AND NORTHEASTERN NEBRASKA...SOUTHEASTERN SOUTH DAKOTA...NORTHEASTERN IOWA...SOUTHERN MINNESOTA...NORTHERN WISCONSIN...UPPER MICHIGAN... ...SUMMARY... Organizing clusters of storms posing a risk for severe wind are possible across parts of the middle Missouri Valley and Upper Midwest into adjacent portions of the Great Lakes region Wednesday through Wednesday night. ...Discussion... Models continue to indicate further suppression of the northeastern Pacific mid-level ridging, with flow becoming more zonal and progressive across the British Columbia coast into the Canadian Prairies during this period. Downstream, it still appears that mid/upper flow will continue to intensify in a belt across Ontario through Quebec, between a significant trough and cyclone slowly migrating eastward across Hudson Bay and prominent ridging initially centered over the Ohio Valley. A cold front trailing the cyclone is still likely to advance more rapidly southward across the Great Plains, to the lee of the Rockies, than across the Upper Midwest and adjacent Great Lakes region. This general evolution has been forecast for several days, but spread has been evident within and among the various model output concerning the synoptic and, particularly, sub-synoptic developments, which persists in latest model runs. Among the details which remain characterized by sizable spread, the cold frontal progression through the Great Plains/mid Missouri Valley vicinity, the strength of a short wave perturbation progressing out of the Pacific Northwest through the central Canadian/U.S. border vicinity, and weak mid/upper perturbations migrating around the southern and northwestern periphery of the interior U.S. ridge, across the Gulf coast and southern Great Plains toward upper Mississippi Valley. These and other smaller-scale perturbations, with low predictability at this time frame, will considerably impact the convective potential for Wednesday through Wednesday night. ...Mid Missouri Valley into Upper Midwest/Great Lakes... While it still appears that the southern fringe of the stronger mid/upper westerlies will not extend south of a corridor from southeastern Minnesota through northern Wisconsin and Upper Michigan, models now generally indicate a belt of moderate south-southwest flow (20-40 kt in the 850-700 mb layer) in the lower/mid-levels will develop across the central Great Plains into the Upper Midwest, ahead of the weak perturbation migrating around the western periphery of the mid-level ridge. Beneath modestly steep lapse rates, but with generally warm profiles, it now appears increasingly probable that seasonably high boundary-layer moisture content, supportive of large mixed-layer CAPE, will extend along the frontal zone from the Upper Midwest/Great Lakes as far southwest as central/northeastern Nebraska by late afternoon. Coupled with the strength of the lower/mid-tropospheric flow, it appears probable that this environment will become supportive of one or two organizing thunderstorm clusters with potential to produce swaths of strong to severe wind gusts. However, based on late model output, including available convection allowing guidance, the potential evolution Wednesday through Wednesday night remains rather uncertain at this time. ...Northern Rockies into Front Range... In the presence of steep lapse rates, moistening easterly to southeasterly near-surface flow, beneath modest westerly flow aloft, may contribute to sufficient destabilization and shear to support widely scattered strong to severe storms. This may include evolving supercells near/just east of the higher terrain late Wednesday afternoon and evening. ..Kerr.. 07/22/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1149 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WEDNESDAY INTO WEDNESDAY NIGHT ACROSS PARTS OF CENTRAL AND NORTHEASTERN NEBRASKA...SOUTHEASTERN SOUTH DAKOTA...NORTHEASTERN IOWA...SOUTHERN MINNESOTA...NORTHERN WISCONSIN...UPPER MICHIGAN... ...SUMMARY... Organizing clusters of storms posing a risk for severe wind are possible across parts of the middle Missouri Valley and Upper Midwest into adjacent portions of the Great Lakes region Wednesday through Wednesday night. ...Discussion... Models continue to indicate further suppression of the northeastern Pacific mid-level ridging, with flow becoming more zonal and progressive across the British Columbia coast into the Canadian Prairies during this period. Downstream, it still appears that mid/upper flow will continue to intensify in a belt across Ontario through Quebec, between a significant trough and cyclone slowly migrating eastward across Hudson Bay and prominent ridging initially centered over the Ohio Valley. A cold front trailing the cyclone is still likely to advance more rapidly southward across the Great Plains, to the lee of the Rockies, than across the Upper Midwest and adjacent Great Lakes region. This general evolution has been forecast for several days, but spread has been evident within and among the various model output concerning the synoptic and, particularly, sub-synoptic developments, which persists in latest model runs. Among the details which remain characterized by sizable spread, the cold frontal progression through the Great Plains/mid Missouri Valley vicinity, the strength of a short wave perturbation progressing out of the Pacific Northwest through the central Canadian/U.S. border vicinity, and weak mid/upper perturbations migrating around the southern and northwestern periphery of the interior U.S. ridge, across the Gulf coast and southern Great Plains toward upper Mississippi Valley. These and other smaller-scale perturbations, with low predictability at this time frame, will considerably impact the convective potential for Wednesday through Wednesday night. ...Mid Missouri Valley into Upper Midwest/Great Lakes... While it still appears that the southern fringe of the stronger mid/upper westerlies will not extend south of a corridor from southeastern Minnesota through northern Wisconsin and Upper Michigan, models now generally indicate a belt of moderate south-southwest flow (20-40 kt in the 850-700 mb layer) in the lower/mid-levels will develop across the central Great Plains into the Upper Midwest, ahead of the weak perturbation migrating around the western periphery of the mid-level ridge. Beneath modestly steep lapse rates, but with generally warm profiles, it now appears increasingly probable that seasonably high boundary-layer moisture content, supportive of large mixed-layer CAPE, will extend along the frontal zone from the Upper Midwest/Great Lakes as far southwest as central/northeastern Nebraska by late afternoon. Coupled with the strength of the lower/mid-tropospheric flow, it appears probable that this environment will become supportive of one or two organizing thunderstorm clusters with potential to produce swaths of strong to severe wind gusts. However, based on late model output, including available convection allowing guidance, the potential evolution Wednesday through Wednesday night remains rather uncertain at this time. ...Northern Rockies into Front Range... In the presence of steep lapse rates, moistening easterly to southeasterly near-surface flow, beneath modest westerly flow aloft, may contribute to sufficient destabilization and shear to support widely scattered strong to severe storms. This may include evolving supercells near/just east of the higher terrain late Wednesday afternoon and evening. ..Kerr.. 07/22/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1149 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WEDNESDAY INTO WEDNESDAY NIGHT ACROSS PARTS OF CENTRAL AND NORTHEASTERN NEBRASKA...SOUTHEASTERN SOUTH DAKOTA...NORTHEASTERN IOWA...SOUTHERN MINNESOTA...NORTHERN WISCONSIN...UPPER MICHIGAN... ...SUMMARY... Organizing clusters of storms posing a risk for severe wind are possible across parts of the middle Missouri Valley and Upper Midwest into adjacent portions of the Great Lakes region Wednesday through Wednesday night. ...Discussion... Models continue to indicate further suppression of the northeastern Pacific mid-level ridging, with flow becoming more zonal and progressive across the British Columbia coast into the Canadian Prairies during this period. Downstream, it still appears that mid/upper flow will continue to intensify in a belt across Ontario through Quebec, between a significant trough and cyclone slowly migrating eastward across Hudson Bay and prominent ridging initially centered over the Ohio Valley. A cold front trailing the cyclone is still likely to advance more rapidly southward across the Great Plains, to the lee of the Rockies, than across the Upper Midwest and adjacent Great Lakes region. This general evolution has been forecast for several days, but spread has been evident within and among the various model output concerning the synoptic and, particularly, sub-synoptic developments, which persists in latest model runs. Among the details which remain characterized by sizable spread, the cold frontal progression through the Great Plains/mid Missouri Valley vicinity, the strength of a short wave perturbation progressing out of the Pacific Northwest through the central Canadian/U.S. border vicinity, and weak mid/upper perturbations migrating around the southern and northwestern periphery of the interior U.S. ridge, across the Gulf coast and southern Great Plains toward upper Mississippi Valley. These and other smaller-scale perturbations, with low predictability at this time frame, will considerably impact the convective potential for Wednesday through Wednesday night. ...Mid Missouri Valley into Upper Midwest/Great Lakes... While it still appears that the southern fringe of the stronger mid/upper westerlies will not extend south of a corridor from southeastern Minnesota through northern Wisconsin and Upper Michigan, models now generally indicate a belt of moderate south-southwest flow (20-40 kt in the 850-700 mb layer) in the lower/mid-levels will develop across the central Great Plains into the Upper Midwest, ahead of the weak perturbation migrating around the western periphery of the mid-level ridge. Beneath modestly steep lapse rates, but with generally warm profiles, it now appears increasingly probable that seasonably high boundary-layer moisture content, supportive of large mixed-layer CAPE, will extend along the frontal zone from the Upper Midwest/Great Lakes as far southwest as central/northeastern Nebraska by late afternoon. Coupled with the strength of the lower/mid-tropospheric flow, it appears probable that this environment will become supportive of one or two organizing thunderstorm clusters with potential to produce swaths of strong to severe wind gusts. However, based on late model output, including available convection allowing guidance, the potential evolution Wednesday through Wednesday night remains rather uncertain at this time. ...Northern Rockies into Front Range... In the presence of steep lapse rates, moistening easterly to southeasterly near-surface flow, beneath modest westerly flow aloft, may contribute to sufficient destabilization and shear to support widely scattered strong to severe storms. This may include evolving supercells near/just east of the higher terrain late Wednesday afternoon and evening. ..Kerr.. 07/22/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1149 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WEDNESDAY INTO WEDNESDAY NIGHT ACROSS PARTS OF CENTRAL AND NORTHEASTERN NEBRASKA...SOUTHEASTERN SOUTH DAKOTA...NORTHEASTERN IOWA...SOUTHERN MINNESOTA...NORTHERN WISCONSIN...UPPER MICHIGAN... ...SUMMARY... Organizing clusters of storms posing a risk for severe wind are possible across parts of the middle Missouri Valley and Upper Midwest into adjacent portions of the Great Lakes region Wednesday through Wednesday night. ...Discussion... Models continue to indicate further suppression of the northeastern Pacific mid-level ridging, with flow becoming more zonal and progressive across the British Columbia coast into the Canadian Prairies during this period. Downstream, it still appears that mid/upper flow will continue to intensify in a belt across Ontario through Quebec, between a significant trough and cyclone slowly migrating eastward across Hudson Bay and prominent ridging initially centered over the Ohio Valley. A cold front trailing the cyclone is still likely to advance more rapidly southward across the Great Plains, to the lee of the Rockies, than across the Upper Midwest and adjacent Great Lakes region. This general evolution has been forecast for several days, but spread has been evident within and among the various model output concerning the synoptic and, particularly, sub-synoptic developments, which persists in latest model runs. Among the details which remain characterized by sizable spread, the cold frontal progression through the Great Plains/mid Missouri Valley vicinity, the strength of a short wave perturbation progressing out of the Pacific Northwest through the central Canadian/U.S. border vicinity, and weak mid/upper perturbations migrating around the southern and northwestern periphery of the interior U.S. ridge, across the Gulf coast and southern Great Plains toward upper Mississippi Valley. These and other smaller-scale perturbations, with low predictability at this time frame, will considerably impact the convective potential for Wednesday through Wednesday night. ...Mid Missouri Valley into Upper Midwest/Great Lakes... While it still appears that the southern fringe of the stronger mid/upper westerlies will not extend south of a corridor from southeastern Minnesota through northern Wisconsin and Upper Michigan, models now generally indicate a belt of moderate south-southwest flow (20-40 kt in the 850-700 mb layer) in the lower/mid-levels will develop across the central Great Plains into the Upper Midwest, ahead of the weak perturbation migrating around the western periphery of the mid-level ridge. Beneath modestly steep lapse rates, but with generally warm profiles, it now appears increasingly probable that seasonably high boundary-layer moisture content, supportive of large mixed-layer CAPE, will extend along the frontal zone from the Upper Midwest/Great Lakes as far southwest as central/northeastern Nebraska by late afternoon. Coupled with the strength of the lower/mid-tropospheric flow, it appears probable that this environment will become supportive of one or two organizing thunderstorm clusters with potential to produce swaths of strong to severe wind gusts. However, based on late model output, including available convection allowing guidance, the potential evolution Wednesday through Wednesday night remains rather uncertain at this time. ...Northern Rockies into Front Range... In the presence of steep lapse rates, moistening easterly to southeasterly near-surface flow, beneath modest westerly flow aloft, may contribute to sufficient destabilization and shear to support widely scattered strong to severe storms. This may include evolving supercells near/just east of the higher terrain late Wednesday afternoon and evening. ..Kerr.. 07/22/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1149 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WEDNESDAY INTO WEDNESDAY NIGHT ACROSS PARTS OF CENTRAL AND NORTHEASTERN NEBRASKA...SOUTHEASTERN SOUTH DAKOTA...NORTHEASTERN IOWA...SOUTHERN MINNESOTA...NORTHERN WISCONSIN...UPPER MICHIGAN... ...SUMMARY... Organizing clusters of storms posing a risk for severe wind are possible across parts of the middle Missouri Valley and Upper Midwest into adjacent portions of the Great Lakes region Wednesday through Wednesday night. ...Discussion... Models continue to indicate further suppression of the northeastern Pacific mid-level ridging, with flow becoming more zonal and progressive across the British Columbia coast into the Canadian Prairies during this period. Downstream, it still appears that mid/upper flow will continue to intensify in a belt across Ontario through Quebec, between a significant trough and cyclone slowly migrating eastward across Hudson Bay and prominent ridging initially centered over the Ohio Valley. A cold front trailing the cyclone is still likely to advance more rapidly southward across the Great Plains, to the lee of the Rockies, than across the Upper Midwest and adjacent Great Lakes region. This general evolution has been forecast for several days, but spread has been evident within and among the various model output concerning the synoptic and, particularly, sub-synoptic developments, which persists in latest model runs. Among the details which remain characterized by sizable spread, the cold frontal progression through the Great Plains/mid Missouri Valley vicinity, the strength of a short wave perturbation progressing out of the Pacific Northwest through the central Canadian/U.S. border vicinity, and weak mid/upper perturbations migrating around the southern and northwestern periphery of the interior U.S. ridge, across the Gulf coast and southern Great Plains toward upper Mississippi Valley. These and other smaller-scale perturbations, with low predictability at this time frame, will considerably impact the convective potential for Wednesday through Wednesday night. ...Mid Missouri Valley into Upper Midwest/Great Lakes... While it still appears that the southern fringe of the stronger mid/upper westerlies will not extend south of a corridor from southeastern Minnesota through northern Wisconsin and Upper Michigan, models now generally indicate a belt of moderate south-southwest flow (20-40 kt in the 850-700 mb layer) in the lower/mid-levels will develop across the central Great Plains into the Upper Midwest, ahead of the weak perturbation migrating around the western periphery of the mid-level ridge. Beneath modestly steep lapse rates, but with generally warm profiles, it now appears increasingly probable that seasonably high boundary-layer moisture content, supportive of large mixed-layer CAPE, will extend along the frontal zone from the Upper Midwest/Great Lakes as far southwest as central/northeastern Nebraska by late afternoon. Coupled with the strength of the lower/mid-tropospheric flow, it appears probable that this environment will become supportive of one or two organizing thunderstorm clusters with potential to produce swaths of strong to severe wind gusts. However, based on late model output, including available convection allowing guidance, the potential evolution Wednesday through Wednesday night remains rather uncertain at this time. ...Northern Rockies into Front Range... In the presence of steep lapse rates, moistening easterly to southeasterly near-surface flow, beneath modest westerly flow aloft, may contribute to sufficient destabilization and shear to support widely scattered strong to severe storms. This may include evolving supercells near/just east of the higher terrain late Wednesday afternoon and evening. ..Kerr.. 07/22/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1149 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WEDNESDAY INTO WEDNESDAY NIGHT ACROSS PARTS OF CENTRAL AND NORTHEASTERN NEBRASKA...SOUTHEASTERN SOUTH DAKOTA...NORTHEASTERN IOWA...SOUTHERN MINNESOTA...NORTHERN WISCONSIN...UPPER MICHIGAN... ...SUMMARY... Organizing clusters of storms posing a risk for severe wind are possible across parts of the middle Missouri Valley and Upper Midwest into adjacent portions of the Great Lakes region Wednesday through Wednesday night. ...Discussion... Models continue to indicate further suppression of the northeastern Pacific mid-level ridging, with flow becoming more zonal and progressive across the British Columbia coast into the Canadian Prairies during this period. Downstream, it still appears that mid/upper flow will continue to intensify in a belt across Ontario through Quebec, between a significant trough and cyclone slowly migrating eastward across Hudson Bay and prominent ridging initially centered over the Ohio Valley. A cold front trailing the cyclone is still likely to advance more rapidly southward across the Great Plains, to the lee of the Rockies, than across the Upper Midwest and adjacent Great Lakes region. This general evolution has been forecast for several days, but spread has been evident within and among the various model output concerning the synoptic and, particularly, sub-synoptic developments, which persists in latest model runs. Among the details which remain characterized by sizable spread, the cold frontal progression through the Great Plains/mid Missouri Valley vicinity, the strength of a short wave perturbation progressing out of the Pacific Northwest through the central Canadian/U.S. border vicinity, and weak mid/upper perturbations migrating around the southern and northwestern periphery of the interior U.S. ridge, across the Gulf coast and southern Great Plains toward upper Mississippi Valley. These and other smaller-scale perturbations, with low predictability at this time frame, will considerably impact the convective potential for Wednesday through Wednesday night. ...Mid Missouri Valley into Upper Midwest/Great Lakes... While it still appears that the southern fringe of the stronger mid/upper westerlies will not extend south of a corridor from southeastern Minnesota through northern Wisconsin and Upper Michigan, models now generally indicate a belt of moderate south-southwest flow (20-40 kt in the 850-700 mb layer) in the lower/mid-levels will develop across the central Great Plains into the Upper Midwest, ahead of the weak perturbation migrating around the western periphery of the mid-level ridge. Beneath modestly steep lapse rates, but with generally warm profiles, it now appears increasingly probable that seasonably high boundary-layer moisture content, supportive of large mixed-layer CAPE, will extend along the frontal zone from the Upper Midwest/Great Lakes as far southwest as central/northeastern Nebraska by late afternoon. Coupled with the strength of the lower/mid-tropospheric flow, it appears probable that this environment will become supportive of one or two organizing thunderstorm clusters with potential to produce swaths of strong to severe wind gusts. However, based on late model output, including available convection allowing guidance, the potential evolution Wednesday through Wednesday night remains rather uncertain at this time. ...Northern Rockies into Front Range... In the presence of steep lapse rates, moistening easterly to southeasterly near-surface flow, beneath modest westerly flow aloft, may contribute to sufficient destabilization and shear to support widely scattered strong to severe storms. This may include evolving supercells near/just east of the higher terrain late Wednesday afternoon and evening. ..Kerr.. 07/22/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Tue Jul 22 2025 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE NORTHERN PLAINS INTO NORTHERN MN... ...SUMMARY... Scattered severe thunderstorms are expected over parts of the northern Plains into the upper Mississippi Valley later today into tonight. ...Northern Plains into the Upper Great Lakes region... An active severe-weather day still appears possible across parts of the northern Plains into the upper MS Valley/Great Lakes, though considerable uncertainty remains regarding the evolution of storms through the day. One or more storm clusters and possibly a remnant MCS may be ongoing at the start of the period somewhere from eastern ND into northern MN, though guidance varies regarding the details. Any organized cluster or MCS that is ongoing may pose a threat for at least localized damaging gusts into parts of northern MN through the morning, along with some hail potential with any semi-discrete cells. A surface low is forecast to move eastward across SD through the day, downstream of a positively tilted upper-level trough over the northern Rockies. An outflow-influenced surface boundary will extend northeast from the low into parts of the eastern Dakotas and northern MN, though its placement is somewhat uncertain by afternoon. Strong instability will develop by afternoon near and south of the boundary, and also within a region of moist east/northeasterly flow north and northwest of the surface low. The strongest mid/upper-level flow will be north of the boundary, but backed low-level flow near the boundary will result in favorable deep-layer shear for organized convection. There will be some potential for supercell development near the surface low and northeastward along the boundary during the afternoon and evening, though coverage is uncertain due to rather subtle large-scale forcing. Any sustained supercells within this environment could pose some tornado threat, in addition to potential for large to very large hail and localized severe gusts. Greater tornado probabilities may be needed if confidence increases in supercell development during the afternoon and evening. Farther west, widely scattered storm development is again expected across parts of MT and northern WY, initially within the post-frontal environment. Moderate instability and favorable deep-layer shear will support a mixture of cells and clusters with hail and severe-wind potential as they move east-northeastward. With time, upscale growth will be possible, either from convection moving out of the northern High Plains, or from storms developing farther east near the surface boundary. This could result in potential for a swath of damaging winds during the evening and overnight, though the favored corridor for this potential remains uncertain at this time. ...IA into southern MN/WI... An MCV generated by the extensive MCC over the central Plains Monday evening is forecast by most 00Z guidance to move northeastward toward IA and southern MN/WI through the period. The extent of flow enhancement and storm development associated with this feature is uncertain, but it is forecast to track across a moist and unstable environment during the afternoon and evening, and could aid in the development of a few strong storms. Locally damaging gusts will be possible, and a tornado cannot be ruled out if the MCV remains somewhat vigorous. ...Parts of the Southeast... A weak cold front will move across parts of the Carolinas and Georgia today into this evening. Very rich moisture (PWs above 2 inches) will support scattered to numerous thunderstorms along/ahead of the front, and in association with the sea breeze. Strong to locally damaging gusts will be possible, mainly during the afternoon and evening. ...Southern/central Rockies/High Plains... Relatively high-based thunderstorms are again expected this afternoon and evening across parts of the central/southern Rockies and adjacent High Plains. Localized strong to severe gusts may accompany these storms, though with relatively modest buoyancy and weak deep-layer shear, the threat appears too disorganized and nebulous for probabilities at this time. ..Dean/Wendt.. 07/22/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Tue Jul 22 2025 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE NORTHERN PLAINS INTO NORTHERN MN... ...SUMMARY... Scattered severe thunderstorms are expected over parts of the northern Plains into the upper Mississippi Valley later today into tonight. ...Northern Plains into the Upper Great Lakes region... An active severe-weather day still appears possible across parts of the northern Plains into the upper MS Valley/Great Lakes, though considerable uncertainty remains regarding the evolution of storms through the day. One or more storm clusters and possibly a remnant MCS may be ongoing at the start of the period somewhere from eastern ND into northern MN, though guidance varies regarding the details. Any organized cluster or MCS that is ongoing may pose a threat for at least localized damaging gusts into parts of northern MN through the morning, along with some hail potential with any semi-discrete cells. A surface low is forecast to move eastward across SD through the day, downstream of a positively tilted upper-level trough over the northern Rockies. An outflow-influenced surface boundary will extend northeast from the low into parts of the eastern Dakotas and northern MN, though its placement is somewhat uncertain by afternoon. Strong instability will develop by afternoon near and south of the boundary, and also within a region of moist east/northeasterly flow north and northwest of the surface low. The strongest mid/upper-level flow will be north of the boundary, but backed low-level flow near the boundary will result in favorable deep-layer shear for organized convection. There will be some potential for supercell development near the surface low and northeastward along the boundary during the afternoon and evening, though coverage is uncertain due to rather subtle large-scale forcing. Any sustained supercells within this environment could pose some tornado threat, in addition to potential for large to very large hail and localized severe gusts. Greater tornado probabilities may be needed if confidence increases in supercell development during the afternoon and evening. Farther west, widely scattered storm development is again expected across parts of MT and northern WY, initially within the post-frontal environment. Moderate instability and favorable deep-layer shear will support a mixture of cells and clusters with hail and severe-wind potential as they move east-northeastward. With time, upscale growth will be possible, either from convection moving out of the northern High Plains, or from storms developing farther east near the surface boundary. This could result in potential for a swath of damaging winds during the evening and overnight, though the favored corridor for this potential remains uncertain at this time. ...IA into southern MN/WI... An MCV generated by the extensive MCC over the central Plains Monday evening is forecast by most 00Z guidance to move northeastward toward IA and southern MN/WI through the period. The extent of flow enhancement and storm development associated with this feature is uncertain, but it is forecast to track across a moist and unstable environment during the afternoon and evening, and could aid in the development of a few strong storms. Locally damaging gusts will be possible, and a tornado cannot be ruled out if the MCV remains somewhat vigorous. ...Parts of the Southeast... A weak cold front will move across parts of the Carolinas and Georgia today into this evening. Very rich moisture (PWs above 2 inches) will support scattered to numerous thunderstorms along/ahead of the front, and in association with the sea breeze. Strong to locally damaging gusts will be possible, mainly during the afternoon and evening. ...Southern/central Rockies/High Plains... Relatively high-based thunderstorms are again expected this afternoon and evening across parts of the central/southern Rockies and adjacent High Plains. Localized strong to severe gusts may accompany these storms, though with relatively modest buoyancy and weak deep-layer shear, the threat appears too disorganized and nebulous for probabilities at this time. ..Dean/Wendt.. 07/22/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Tue Jul 22 2025 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE NORTHERN PLAINS INTO NORTHERN MN... ...SUMMARY... Scattered severe thunderstorms are expected over parts of the northern Plains into the upper Mississippi Valley later today into tonight. ...Northern Plains into the Upper Great Lakes region... An active severe-weather day still appears possible across parts of the northern Plains into the upper MS Valley/Great Lakes, though considerable uncertainty remains regarding the evolution of storms through the day. One or more storm clusters and possibly a remnant MCS may be ongoing at the start of the period somewhere from eastern ND into northern MN, though guidance varies regarding the details. Any organized cluster or MCS that is ongoing may pose a threat for at least localized damaging gusts into parts of northern MN through the morning, along with some hail potential with any semi-discrete cells. A surface low is forecast to move eastward across SD through the day, downstream of a positively tilted upper-level trough over the northern Rockies. An outflow-influenced surface boundary will extend northeast from the low into parts of the eastern Dakotas and northern MN, though its placement is somewhat uncertain by afternoon. Strong instability will develop by afternoon near and south of the boundary, and also within a region of moist east/northeasterly flow north and northwest of the surface low. The strongest mid/upper-level flow will be north of the boundary, but backed low-level flow near the boundary will result in favorable deep-layer shear for organized convection. There will be some potential for supercell development near the surface low and northeastward along the boundary during the afternoon and evening, though coverage is uncertain due to rather subtle large-scale forcing. Any sustained supercells within this environment could pose some tornado threat, in addition to potential for large to very large hail and localized severe gusts. Greater tornado probabilities may be needed if confidence increases in supercell development during the afternoon and evening. Farther west, widely scattered storm development is again expected across parts of MT and northern WY, initially within the post-frontal environment. Moderate instability and favorable deep-layer shear will support a mixture of cells and clusters with hail and severe-wind potential as they move east-northeastward. With time, upscale growth will be possible, either from convection moving out of the northern High Plains, or from storms developing farther east near the surface boundary. This could result in potential for a swath of damaging winds during the evening and overnight, though the favored corridor for this potential remains uncertain at this time. ...IA into southern MN/WI... An MCV generated by the extensive MCC over the central Plains Monday evening is forecast by most 00Z guidance to move northeastward toward IA and southern MN/WI through the period. The extent of flow enhancement and storm development associated with this feature is uncertain, but it is forecast to track across a moist and unstable environment during the afternoon and evening, and could aid in the development of a few strong storms. Locally damaging gusts will be possible, and a tornado cannot be ruled out if the MCV remains somewhat vigorous. ...Parts of the Southeast... A weak cold front will move across parts of the Carolinas and Georgia today into this evening. Very rich moisture (PWs above 2 inches) will support scattered to numerous thunderstorms along/ahead of the front, and in association with the sea breeze. Strong to locally damaging gusts will be possible, mainly during the afternoon and evening. ...Southern/central Rockies/High Plains... Relatively high-based thunderstorms are again expected this afternoon and evening across parts of the central/southern Rockies and adjacent High Plains. Localized strong to severe gusts may accompany these storms, though with relatively modest buoyancy and weak deep-layer shear, the threat appears too disorganized and nebulous for probabilities at this time. ..Dean/Wendt.. 07/22/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Tue Jul 22 2025 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE NORTHERN PLAINS INTO NORTHERN MN... ...SUMMARY... Scattered severe thunderstorms are expected over parts of the northern Plains into the upper Mississippi Valley later today into tonight. ...Northern Plains into the Upper Great Lakes region... An active severe-weather day still appears possible across parts of the northern Plains into the upper MS Valley/Great Lakes, though considerable uncertainty remains regarding the evolution of storms through the day. One or more storm clusters and possibly a remnant MCS may be ongoing at the start of the period somewhere from eastern ND into northern MN, though guidance varies regarding the details. Any organized cluster or MCS that is ongoing may pose a threat for at least localized damaging gusts into parts of northern MN through the morning, along with some hail potential with any semi-discrete cells. A surface low is forecast to move eastward across SD through the day, downstream of a positively tilted upper-level trough over the northern Rockies. An outflow-influenced surface boundary will extend northeast from the low into parts of the eastern Dakotas and northern MN, though its placement is somewhat uncertain by afternoon. Strong instability will develop by afternoon near and south of the boundary, and also within a region of moist east/northeasterly flow north and northwest of the surface low. The strongest mid/upper-level flow will be north of the boundary, but backed low-level flow near the boundary will result in favorable deep-layer shear for organized convection. There will be some potential for supercell development near the surface low and northeastward along the boundary during the afternoon and evening, though coverage is uncertain due to rather subtle large-scale forcing. Any sustained supercells within this environment could pose some tornado threat, in addition to potential for large to very large hail and localized severe gusts. Greater tornado probabilities may be needed if confidence increases in supercell development during the afternoon and evening. Farther west, widely scattered storm development is again expected across parts of MT and northern WY, initially within the post-frontal environment. Moderate instability and favorable deep-layer shear will support a mixture of cells and clusters with hail and severe-wind potential as they move east-northeastward. With time, upscale growth will be possible, either from convection moving out of the northern High Plains, or from storms developing farther east near the surface boundary. This could result in potential for a swath of damaging winds during the evening and overnight, though the favored corridor for this potential remains uncertain at this time. ...IA into southern MN/WI... An MCV generated by the extensive MCC over the central Plains Monday evening is forecast by most 00Z guidance to move northeastward toward IA and southern MN/WI through the period. The extent of flow enhancement and storm development associated with this feature is uncertain, but it is forecast to track across a moist and unstable environment during the afternoon and evening, and could aid in the development of a few strong storms. Locally damaging gusts will be possible, and a tornado cannot be ruled out if the MCV remains somewhat vigorous. ...Parts of the Southeast... A weak cold front will move across parts of the Carolinas and Georgia today into this evening. Very rich moisture (PWs above 2 inches) will support scattered to numerous thunderstorms along/ahead of the front, and in association with the sea breeze. Strong to locally damaging gusts will be possible, mainly during the afternoon and evening. ...Southern/central Rockies/High Plains... Relatively high-based thunderstorms are again expected this afternoon and evening across parts of the central/southern Rockies and adjacent High Plains. Localized strong to severe gusts may accompany these storms, though with relatively modest buoyancy and weak deep-layer shear, the threat appears too disorganized and nebulous for probabilities at this time. ..Dean/Wendt.. 07/22/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Tue Jul 22 2025 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE NORTHERN PLAINS INTO NORTHERN MN... ...SUMMARY... Scattered severe thunderstorms are expected over parts of the northern Plains into the upper Mississippi Valley later today into tonight. ...Northern Plains into the Upper Great Lakes region... An active severe-weather day still appears possible across parts of the northern Plains into the upper MS Valley/Great Lakes, though considerable uncertainty remains regarding the evolution of storms through the day. One or more storm clusters and possibly a remnant MCS may be ongoing at the start of the period somewhere from eastern ND into northern MN, though guidance varies regarding the details. Any organized cluster or MCS that is ongoing may pose a threat for at least localized damaging gusts into parts of northern MN through the morning, along with some hail potential with any semi-discrete cells. A surface low is forecast to move eastward across SD through the day, downstream of a positively tilted upper-level trough over the northern Rockies. An outflow-influenced surface boundary will extend northeast from the low into parts of the eastern Dakotas and northern MN, though its placement is somewhat uncertain by afternoon. Strong instability will develop by afternoon near and south of the boundary, and also within a region of moist east/northeasterly flow north and northwest of the surface low. The strongest mid/upper-level flow will be north of the boundary, but backed low-level flow near the boundary will result in favorable deep-layer shear for organized convection. There will be some potential for supercell development near the surface low and northeastward along the boundary during the afternoon and evening, though coverage is uncertain due to rather subtle large-scale forcing. Any sustained supercells within this environment could pose some tornado threat, in addition to potential for large to very large hail and localized severe gusts. Greater tornado probabilities may be needed if confidence increases in supercell development during the afternoon and evening. Farther west, widely scattered storm development is again expected across parts of MT and northern WY, initially within the post-frontal environment. Moderate instability and favorable deep-layer shear will support a mixture of cells and clusters with hail and severe-wind potential as they move east-northeastward. With time, upscale growth will be possible, either from convection moving out of the northern High Plains, or from storms developing farther east near the surface boundary. This could result in potential for a swath of damaging winds during the evening and overnight, though the favored corridor for this potential remains uncertain at this time. ...IA into southern MN/WI... An MCV generated by the extensive MCC over the central Plains Monday evening is forecast by most 00Z guidance to move northeastward toward IA and southern MN/WI through the period. The extent of flow enhancement and storm development associated with this feature is uncertain, but it is forecast to track across a moist and unstable environment during the afternoon and evening, and could aid in the development of a few strong storms. Locally damaging gusts will be possible, and a tornado cannot be ruled out if the MCV remains somewhat vigorous. ...Parts of the Southeast... A weak cold front will move across parts of the Carolinas and Georgia today into this evening. Very rich moisture (PWs above 2 inches) will support scattered to numerous thunderstorms along/ahead of the front, and in association with the sea breeze. Strong to locally damaging gusts will be possible, mainly during the afternoon and evening. ...Southern/central Rockies/High Plains... Relatively high-based thunderstorms are again expected this afternoon and evening across parts of the central/southern Rockies and adjacent High Plains. Localized strong to severe gusts may accompany these storms, though with relatively modest buoyancy and weak deep-layer shear, the threat appears too disorganized and nebulous for probabilities at this time. ..Dean/Wendt.. 07/22/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Tue Jul 22 2025 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE NORTHERN PLAINS INTO NORTHERN MN... ...SUMMARY... Scattered severe thunderstorms are expected over parts of the northern Plains into the upper Mississippi Valley later today into tonight. ...Northern Plains into the Upper Great Lakes region... An active severe-weather day still appears possible across parts of the northern Plains into the upper MS Valley/Great Lakes, though considerable uncertainty remains regarding the evolution of storms through the day. One or more storm clusters and possibly a remnant MCS may be ongoing at the start of the period somewhere from eastern ND into northern MN, though guidance varies regarding the details. Any organized cluster or MCS that is ongoing may pose a threat for at least localized damaging gusts into parts of northern MN through the morning, along with some hail potential with any semi-discrete cells. A surface low is forecast to move eastward across SD through the day, downstream of a positively tilted upper-level trough over the northern Rockies. An outflow-influenced surface boundary will extend northeast from the low into parts of the eastern Dakotas and northern MN, though its placement is somewhat uncertain by afternoon. Strong instability will develop by afternoon near and south of the boundary, and also within a region of moist east/northeasterly flow north and northwest of the surface low. The strongest mid/upper-level flow will be north of the boundary, but backed low-level flow near the boundary will result in favorable deep-layer shear for organized convection. There will be some potential for supercell development near the surface low and northeastward along the boundary during the afternoon and evening, though coverage is uncertain due to rather subtle large-scale forcing. Any sustained supercells within this environment could pose some tornado threat, in addition to potential for large to very large hail and localized severe gusts. Greater tornado probabilities may be needed if confidence increases in supercell development during the afternoon and evening. Farther west, widely scattered storm development is again expected across parts of MT and northern WY, initially within the post-frontal environment. Moderate instability and favorable deep-layer shear will support a mixture of cells and clusters with hail and severe-wind potential as they move east-northeastward. With time, upscale growth will be possible, either from convection moving out of the northern High Plains, or from storms developing farther east near the surface boundary. This could result in potential for a swath of damaging winds during the evening and overnight, though the favored corridor for this potential remains uncertain at this time. ...IA into southern MN/WI... An MCV generated by the extensive MCC over the central Plains Monday evening is forecast by most 00Z guidance to move northeastward toward IA and southern MN/WI through the period. The extent of flow enhancement and storm development associated with this feature is uncertain, but it is forecast to track across a moist and unstable environment during the afternoon and evening, and could aid in the development of a few strong storms. Locally damaging gusts will be possible, and a tornado cannot be ruled out if the MCV remains somewhat vigorous. ...Parts of the Southeast... A weak cold front will move across parts of the Carolinas and Georgia today into this evening. Very rich moisture (PWs above 2 inches) will support scattered to numerous thunderstorms along/ahead of the front, and in association with the sea breeze. Strong to locally damaging gusts will be possible, mainly during the afternoon and evening. ...Southern/central Rockies/High Plains... Relatively high-based thunderstorms are again expected this afternoon and evening across parts of the central/southern Rockies and adjacent High Plains. Localized strong to severe gusts may accompany these storms, though with relatively modest buoyancy and weak deep-layer shear, the threat appears too disorganized and nebulous for probabilities at this time. ..Dean/Wendt.. 07/22/2025 Read more