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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 PM CDT Wed Sep 03 2025 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE TENNESSEE VALLEY AND SOUTHERN APPALACHIANS NORTHWARD INTO NEW YORK... ...SUMMARY... Scattered strong thunderstorms capable of producing locally damaging wind gusts may impact a corridor from the Tennessee Valley and southern Appalachians northward through northern New York on Thursday. ...Synopsis... A deep/vertically stacked low pressure system will retrograde slightly westward over Ontario through the forecast period, while broad large-scale troughing encompasses much of the eastern CONUS. An embedded midlevel trough will track eastward across the Lower Great Lakes during the day, while a related cold front extending from NY south-southwestward along the Appalachians moves gradually eastward. ...TN Valley and Southern Appalachians northward into NY... Despite poor midlevel lapse rates, diurnal heating amid middle/upper 50 to lower 60s dewpoints will result in a corridor of weak to locally moderate surface-based buoyancy ahead of the front during the afternoon. Scattered thunderstorms are expected along/ahead of the front, where 30-40 kt of effective shear will promote loosely organized multicell clusters and line segments. The stronger storm clusters will be capable of producing locally damaging wind gusts through the afternoon. ...Northern Plains... On the backside of the large-scale trough, a robust midlevel speed maximum will move into the northern Plains during the day. Strong forcing for ascent and cold temperatures aloft will support isolated thunderstorms. While deep-layer shear will be sufficient for organized storms, the post-frontal nature of this activity should limit the overall severe risk. ..Weinman.. 09/03/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 PM CDT Wed Sep 03 2025 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE TENNESSEE VALLEY AND SOUTHERN APPALACHIANS NORTHWARD INTO NEW YORK... ...SUMMARY... Scattered strong thunderstorms capable of producing locally damaging wind gusts may impact a corridor from the Tennessee Valley and southern Appalachians northward through northern New York on Thursday. ...Synopsis... A deep/vertically stacked low pressure system will retrograde slightly westward over Ontario through the forecast period, while broad large-scale troughing encompasses much of the eastern CONUS. An embedded midlevel trough will track eastward across the Lower Great Lakes during the day, while a related cold front extending from NY south-southwestward along the Appalachians moves gradually eastward. ...TN Valley and Southern Appalachians northward into NY... Despite poor midlevel lapse rates, diurnal heating amid middle/upper 50 to lower 60s dewpoints will result in a corridor of weak to locally moderate surface-based buoyancy ahead of the front during the afternoon. Scattered thunderstorms are expected along/ahead of the front, where 30-40 kt of effective shear will promote loosely organized multicell clusters and line segments. The stronger storm clusters will be capable of producing locally damaging wind gusts through the afternoon. ...Northern Plains... On the backside of the large-scale trough, a robust midlevel speed maximum will move into the northern Plains during the day. Strong forcing for ascent and cold temperatures aloft will support isolated thunderstorms. While deep-layer shear will be sufficient for organized storms, the post-frontal nature of this activity should limit the overall severe risk. ..Weinman.. 09/03/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 PM CDT Wed Sep 03 2025 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE TENNESSEE VALLEY AND SOUTHERN APPALACHIANS NORTHWARD INTO NEW YORK... ...SUMMARY... Scattered strong thunderstorms capable of producing locally damaging wind gusts may impact a corridor from the Tennessee Valley and southern Appalachians northward through northern New York on Thursday. ...Synopsis... A deep/vertically stacked low pressure system will retrograde slightly westward over Ontario through the forecast period, while broad large-scale troughing encompasses much of the eastern CONUS. An embedded midlevel trough will track eastward across the Lower Great Lakes during the day, while a related cold front extending from NY south-southwestward along the Appalachians moves gradually eastward. ...TN Valley and Southern Appalachians northward into NY... Despite poor midlevel lapse rates, diurnal heating amid middle/upper 50 to lower 60s dewpoints will result in a corridor of weak to locally moderate surface-based buoyancy ahead of the front during the afternoon. Scattered thunderstorms are expected along/ahead of the front, where 30-40 kt of effective shear will promote loosely organized multicell clusters and line segments. The stronger storm clusters will be capable of producing locally damaging wind gusts through the afternoon. ...Northern Plains... On the backside of the large-scale trough, a robust midlevel speed maximum will move into the northern Plains during the day. Strong forcing for ascent and cold temperatures aloft will support isolated thunderstorms. While deep-layer shear will be sufficient for organized storms, the post-frontal nature of this activity should limit the overall severe risk. ..Weinman.. 09/03/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 PM CDT Wed Sep 03 2025 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE TENNESSEE VALLEY AND SOUTHERN APPALACHIANS NORTHWARD INTO NEW YORK... ...SUMMARY... Scattered strong thunderstorms capable of producing locally damaging wind gusts may impact a corridor from the Tennessee Valley and southern Appalachians northward through northern New York on Thursday. ...Synopsis... A deep/vertically stacked low pressure system will retrograde slightly westward over Ontario through the forecast period, while broad large-scale troughing encompasses much of the eastern CONUS. An embedded midlevel trough will track eastward across the Lower Great Lakes during the day, while a related cold front extending from NY south-southwestward along the Appalachians moves gradually eastward. ...TN Valley and Southern Appalachians northward into NY... Despite poor midlevel lapse rates, diurnal heating amid middle/upper 50 to lower 60s dewpoints will result in a corridor of weak to locally moderate surface-based buoyancy ahead of the front during the afternoon. Scattered thunderstorms are expected along/ahead of the front, where 30-40 kt of effective shear will promote loosely organized multicell clusters and line segments. The stronger storm clusters will be capable of producing locally damaging wind gusts through the afternoon. ...Northern Plains... On the backside of the large-scale trough, a robust midlevel speed maximum will move into the northern Plains during the day. Strong forcing for ascent and cold temperatures aloft will support isolated thunderstorms. While deep-layer shear will be sufficient for organized storms, the post-frontal nature of this activity should limit the overall severe risk. ..Weinman.. 09/03/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 PM CDT Wed Sep 03 2025 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE TENNESSEE VALLEY AND SOUTHERN APPALACHIANS NORTHWARD INTO NEW YORK... ...SUMMARY... Scattered strong thunderstorms capable of producing locally damaging wind gusts may impact a corridor from the Tennessee Valley and southern Appalachians northward through northern New York on Thursday. ...Synopsis... A deep/vertically stacked low pressure system will retrograde slightly westward over Ontario through the forecast period, while broad large-scale troughing encompasses much of the eastern CONUS. An embedded midlevel trough will track eastward across the Lower Great Lakes during the day, while a related cold front extending from NY south-southwestward along the Appalachians moves gradually eastward. ...TN Valley and Southern Appalachians northward into NY... Despite poor midlevel lapse rates, diurnal heating amid middle/upper 50 to lower 60s dewpoints will result in a corridor of weak to locally moderate surface-based buoyancy ahead of the front during the afternoon. Scattered thunderstorms are expected along/ahead of the front, where 30-40 kt of effective shear will promote loosely organized multicell clusters and line segments. The stronger storm clusters will be capable of producing locally damaging wind gusts through the afternoon. ...Northern Plains... On the backside of the large-scale trough, a robust midlevel speed maximum will move into the northern Plains during the day. Strong forcing for ascent and cold temperatures aloft will support isolated thunderstorms. While deep-layer shear will be sufficient for organized storms, the post-frontal nature of this activity should limit the overall severe risk. ..Weinman.. 09/03/2025 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1155 AM CDT Wed Sep 03 2025 Valid 031700Z - 041200Z An upper-level trough supporting ongoing convection across the northern Sierra Nevada will promote expanding showers and thunderstorms across northern CA as well as the Cascades and south-central OR later this afternoon. Additional lightning ignitions are possible, particularly in drier, heavier fuels along the Shasta Siskiyous and Cascades. The northeast extent of dry thunderstorm highlights was trimmed across portions of central OR as well as the northern Sacramento Valley area, supported by latest CAM and ensemble model guidance. ..Williams.. 09/03/2025 .PREV DISCUSSION... /ISSUED 0149 AM CDT Wed Sep 03 2025/ ...Synopsis... A weak upper-level trough will continue to move northward across northern California into the Pacific Northwest on Wednesday. Lift associated with this feature will promote isolated to scattered thunderstorm activity. Thunderstorms will likely be ongoing at the beginning of the period with a second round developing by the afternoon. Overall, a mix of wet/dry thunderstorms is expected across the driest fuels in northern California, far western Nevada, and central Oregon. While locally higher totals will be possible in the strongest storms, ensemble guidance generally shows < 0.10" across much of this region. New lightning starts were reported on Tuesday in these areas, with rainfall amounts 0.10-0.25". An isolated dry thunderstorm area was maintained with this outlook to support this potential. ...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 1155 AM CDT Wed Sep 03 2025 Valid 031700Z - 041200Z An upper-level trough supporting ongoing convection across the northern Sierra Nevada will promote expanding showers and thunderstorms across northern CA as well as the Cascades and south-central OR later this afternoon. Additional lightning ignitions are possible, particularly in drier, heavier fuels along the Shasta Siskiyous and Cascades. The northeast extent of dry thunderstorm highlights was trimmed across portions of central OR as well as the northern Sacramento Valley area, supported by latest CAM and ensemble model guidance. ..Williams.. 09/03/2025 .PREV DISCUSSION... /ISSUED 0149 AM CDT Wed Sep 03 2025/ ...Synopsis... A weak upper-level trough will continue to move northward across northern California into the Pacific Northwest on Wednesday. Lift associated with this feature will promote isolated to scattered thunderstorm activity. Thunderstorms will likely be ongoing at the beginning of the period with a second round developing by the afternoon. Overall, a mix of wet/dry thunderstorms is expected across the driest fuels in northern California, far western Nevada, and central Oregon. While locally higher totals will be possible in the strongest storms, ensemble guidance generally shows < 0.10" across much of this region. New lightning starts were reported on Tuesday in these areas, with rainfall amounts 0.10-0.25". An isolated dry thunderstorm area was maintained with this outlook to support this potential. ...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 1155 AM CDT Wed Sep 03 2025 Valid 031700Z - 041200Z An upper-level trough supporting ongoing convection across the northern Sierra Nevada will promote expanding showers and thunderstorms across northern CA as well as the Cascades and south-central OR later this afternoon. Additional lightning ignitions are possible, particularly in drier, heavier fuels along the Shasta Siskiyous and Cascades. The northeast extent of dry thunderstorm highlights was trimmed across portions of central OR as well as the northern Sacramento Valley area, supported by latest CAM and ensemble model guidance. ..Williams.. 09/03/2025 .PREV DISCUSSION... /ISSUED 0149 AM CDT Wed Sep 03 2025/ ...Synopsis... A weak upper-level trough will continue to move northward across northern California into the Pacific Northwest on Wednesday. Lift associated with this feature will promote isolated to scattered thunderstorm activity. Thunderstorms will likely be ongoing at the beginning of the period with a second round developing by the afternoon. Overall, a mix of wet/dry thunderstorms is expected across the driest fuels in northern California, far western Nevada, and central Oregon. While locally higher totals will be possible in the strongest storms, ensemble guidance generally shows < 0.10" across much of this region. New lightning starts were reported on Tuesday in these areas, with rainfall amounts 0.10-0.25". An isolated dry thunderstorm area was maintained with this outlook to support this potential. ...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 1155 AM CDT Wed Sep 03 2025 Valid 031700Z - 041200Z An upper-level trough supporting ongoing convection across the northern Sierra Nevada will promote expanding showers and thunderstorms across northern CA as well as the Cascades and south-central OR later this afternoon. Additional lightning ignitions are possible, particularly in drier, heavier fuels along the Shasta Siskiyous and Cascades. The northeast extent of dry thunderstorm highlights was trimmed across portions of central OR as well as the northern Sacramento Valley area, supported by latest CAM and ensemble model guidance. ..Williams.. 09/03/2025 .PREV DISCUSSION... /ISSUED 0149 AM CDT Wed Sep 03 2025/ ...Synopsis... A weak upper-level trough will continue to move northward across northern California into the Pacific Northwest on Wednesday. Lift associated with this feature will promote isolated to scattered thunderstorm activity. Thunderstorms will likely be ongoing at the beginning of the period with a second round developing by the afternoon. Overall, a mix of wet/dry thunderstorms is expected across the driest fuels in northern California, far western Nevada, and central Oregon. While locally higher totals will be possible in the strongest storms, ensemble guidance generally shows < 0.10" across much of this region. New lightning starts were reported on Tuesday in these areas, with rainfall amounts 0.10-0.25". An isolated dry thunderstorm area was maintained with this outlook to support this potential. ...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 1155 AM CDT Wed Sep 03 2025 Valid 031700Z - 041200Z An upper-level trough supporting ongoing convection across the northern Sierra Nevada will promote expanding showers and thunderstorms across northern CA as well as the Cascades and south-central OR later this afternoon. Additional lightning ignitions are possible, particularly in drier, heavier fuels along the Shasta Siskiyous and Cascades. The northeast extent of dry thunderstorm highlights was trimmed across portions of central OR as well as the northern Sacramento Valley area, supported by latest CAM and ensemble model guidance. ..Williams.. 09/03/2025 .PREV DISCUSSION... /ISSUED 0149 AM CDT Wed Sep 03 2025/ ...Synopsis... A weak upper-level trough will continue to move northward across northern California into the Pacific Northwest on Wednesday. Lift associated with this feature will promote isolated to scattered thunderstorm activity. Thunderstorms will likely be ongoing at the beginning of the period with a second round developing by the afternoon. Overall, a mix of wet/dry thunderstorms is expected across the driest fuels in northern California, far western Nevada, and central Oregon. While locally higher totals will be possible in the strongest storms, ensemble guidance generally shows < 0.10" across much of this region. New lightning starts were reported on Tuesday in these areas, with rainfall amounts 0.10-0.25". An isolated dry thunderstorm area was maintained with this outlook to support this potential. ...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 1155 AM CDT Wed Sep 03 2025 Valid 031700Z - 041200Z An upper-level trough supporting ongoing convection across the northern Sierra Nevada will promote expanding showers and thunderstorms across northern CA as well as the Cascades and south-central OR later this afternoon. Additional lightning ignitions are possible, particularly in drier, heavier fuels along the Shasta Siskiyous and Cascades. The northeast extent of dry thunderstorm highlights was trimmed across portions of central OR as well as the northern Sacramento Valley area, supported by latest CAM and ensemble model guidance. ..Williams.. 09/03/2025 .PREV DISCUSSION... /ISSUED 0149 AM CDT Wed Sep 03 2025/ ...Synopsis... A weak upper-level trough will continue to move northward across northern California into the Pacific Northwest on Wednesday. Lift associated with this feature will promote isolated to scattered thunderstorm activity. Thunderstorms will likely be ongoing at the beginning of the period with a second round developing by the afternoon. Overall, a mix of wet/dry thunderstorms is expected across the driest fuels in northern California, far western Nevada, and central Oregon. While locally higher totals will be possible in the strongest storms, ensemble guidance generally shows < 0.10" across much of this region. New lightning starts were reported on Tuesday in these areas, with rainfall amounts 0.10-0.25". An isolated dry thunderstorm area was maintained with this outlook to support this potential. ...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 1128 AM CDT Wed Sep 03 2025 Valid 031630Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS AND LOWER MISSOURI VALLEY... ...SUMMARY... Scattered thunderstorms capable of producing large to very large hail and severe wind gusts should occur this afternoon and evening across parts of the central Plains and lower Missouri Valley. ...Central Plains into the Lower Missouri Valley... A mid-level shortwave trough over southern SD/eastern NE will continue to advance quickly southeastward today as a large-scale upper-level low moves from western ON to near Lake Superior through the period. The shortwave trough is forecast to reach the lower MO Valley by late afternoon, with an attendant belt of moderately strong northwesterly mid/high-level flow overspreading the central Plains into the mid MS Valley. At the surface, a cold front will advance southward across parts of the central Plains and lower MO Valley, with generally low to mid 60s surface dewpoints present ahead of the boundary. Diurnal heating of this airmass will contribute to moderate instability (MLCAPE around 1000-2000 J/kg) by mid afternoon across central/eastern KS, with weaker instability forecast with eastward extent into MO. As convective inhibition gradually erodes near the front, scattered thunderstorms will likely develop along its length from central KS into the lower MO Valley during the 20-00Z period. Around 35-55 kt of northwesterly flow in the 500-250 mb layer will yield similar values of effective bulk shear, which will support organized updrafts. A few supercells will probably evolve across central/eastern KS and perhaps into western MO, where the main risk will be large to very large hail given steep lapse rates aloft and favorable shear. Severe wind gusts will also be possible with these supercells, or any small clusters/bowing segments that can develop where low-level lapse rates are steepest (mainly KS into northwest OK and parts of the OK/TX Panhandles). Some severe threat should persist into the evening as multiple small clusters move southward into southern KS and adjacent portions of far northern OK and southwest MO, before they eventually weaken as convective inhibition increases with nocturnal cooling. ...Great Lakes/Midwest... Additional thunderstorms should develop this afternoon along/near the cold front across parts of Lower MI into central IL. Poor lapse rates aloft and limited low-level moisture (reference 12Z soundings from APX and ILX) will likely temper the degree of instability that can develop, even with diurnal heating. While occasional strong/gusty winds appear possible with thunderstorms that spread east-southeastward this afternoon and evening, the overall severe threat should remain fairly limited. ..Gleason/Lyons.. 09/03/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Wed Sep 03 2025 Valid 031630Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS AND LOWER MISSOURI VALLEY... ...SUMMARY... Scattered thunderstorms capable of producing large to very large hail and severe wind gusts should occur this afternoon and evening across parts of the central Plains and lower Missouri Valley. ...Central Plains into the Lower Missouri Valley... A mid-level shortwave trough over southern SD/eastern NE will continue to advance quickly southeastward today as a large-scale upper-level low moves from western ON to near Lake Superior through the period. The shortwave trough is forecast to reach the lower MO Valley by late afternoon, with an attendant belt of moderately strong northwesterly mid/high-level flow overspreading the central Plains into the mid MS Valley. At the surface, a cold front will advance southward across parts of the central Plains and lower MO Valley, with generally low to mid 60s surface dewpoints present ahead of the boundary. Diurnal heating of this airmass will contribute to moderate instability (MLCAPE around 1000-2000 J/kg) by mid afternoon across central/eastern KS, with weaker instability forecast with eastward extent into MO. As convective inhibition gradually erodes near the front, scattered thunderstorms will likely develop along its length from central KS into the lower MO Valley during the 20-00Z period. Around 35-55 kt of northwesterly flow in the 500-250 mb layer will yield similar values of effective bulk shear, which will support organized updrafts. A few supercells will probably evolve across central/eastern KS and perhaps into western MO, where the main risk will be large to very large hail given steep lapse rates aloft and favorable shear. Severe wind gusts will also be possible with these supercells, or any small clusters/bowing segments that can develop where low-level lapse rates are steepest (mainly KS into northwest OK and parts of the OK/TX Panhandles). Some severe threat should persist into the evening as multiple small clusters move southward into southern KS and adjacent portions of far northern OK and southwest MO, before they eventually weaken as convective inhibition increases with nocturnal cooling. ...Great Lakes/Midwest... Additional thunderstorms should develop this afternoon along/near the cold front across parts of Lower MI into central IL. Poor lapse rates aloft and limited low-level moisture (reference 12Z soundings from APX and ILX) will likely temper the degree of instability that can develop, even with diurnal heating. While occasional strong/gusty winds appear possible with thunderstorms that spread east-southeastward this afternoon and evening, the overall severe threat should remain fairly limited. ..Gleason/Lyons.. 09/03/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Wed Sep 03 2025 Valid 031630Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS AND LOWER MISSOURI VALLEY... ...SUMMARY... Scattered thunderstorms capable of producing large to very large hail and severe wind gusts should occur this afternoon and evening across parts of the central Plains and lower Missouri Valley. ...Central Plains into the Lower Missouri Valley... A mid-level shortwave trough over southern SD/eastern NE will continue to advance quickly southeastward today as a large-scale upper-level low moves from western ON to near Lake Superior through the period. The shortwave trough is forecast to reach the lower MO Valley by late afternoon, with an attendant belt of moderately strong northwesterly mid/high-level flow overspreading the central Plains into the mid MS Valley. At the surface, a cold front will advance southward across parts of the central Plains and lower MO Valley, with generally low to mid 60s surface dewpoints present ahead of the boundary. Diurnal heating of this airmass will contribute to moderate instability (MLCAPE around 1000-2000 J/kg) by mid afternoon across central/eastern KS, with weaker instability forecast with eastward extent into MO. As convective inhibition gradually erodes near the front, scattered thunderstorms will likely develop along its length from central KS into the lower MO Valley during the 20-00Z period. Around 35-55 kt of northwesterly flow in the 500-250 mb layer will yield similar values of effective bulk shear, which will support organized updrafts. A few supercells will probably evolve across central/eastern KS and perhaps into western MO, where the main risk will be large to very large hail given steep lapse rates aloft and favorable shear. Severe wind gusts will also be possible with these supercells, or any small clusters/bowing segments that can develop where low-level lapse rates are steepest (mainly KS into northwest OK and parts of the OK/TX Panhandles). Some severe threat should persist into the evening as multiple small clusters move southward into southern KS and adjacent portions of far northern OK and southwest MO, before they eventually weaken as convective inhibition increases with nocturnal cooling. ...Great Lakes/Midwest... Additional thunderstorms should develop this afternoon along/near the cold front across parts of Lower MI into central IL. Poor lapse rates aloft and limited low-level moisture (reference 12Z soundings from APX and ILX) will likely temper the degree of instability that can develop, even with diurnal heating. While occasional strong/gusty winds appear possible with thunderstorms that spread east-southeastward this afternoon and evening, the overall severe threat should remain fairly limited. ..Gleason/Lyons.. 09/03/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Wed Sep 03 2025 Valid 031630Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS AND LOWER MISSOURI VALLEY... ...SUMMARY... Scattered thunderstorms capable of producing large to very large hail and severe wind gusts should occur this afternoon and evening across parts of the central Plains and lower Missouri Valley. ...Central Plains into the Lower Missouri Valley... A mid-level shortwave trough over southern SD/eastern NE will continue to advance quickly southeastward today as a large-scale upper-level low moves from western ON to near Lake Superior through the period. The shortwave trough is forecast to reach the lower MO Valley by late afternoon, with an attendant belt of moderately strong northwesterly mid/high-level flow overspreading the central Plains into the mid MS Valley. At the surface, a cold front will advance southward across parts of the central Plains and lower MO Valley, with generally low to mid 60s surface dewpoints present ahead of the boundary. Diurnal heating of this airmass will contribute to moderate instability (MLCAPE around 1000-2000 J/kg) by mid afternoon across central/eastern KS, with weaker instability forecast with eastward extent into MO. As convective inhibition gradually erodes near the front, scattered thunderstorms will likely develop along its length from central KS into the lower MO Valley during the 20-00Z period. Around 35-55 kt of northwesterly flow in the 500-250 mb layer will yield similar values of effective bulk shear, which will support organized updrafts. A few supercells will probably evolve across central/eastern KS and perhaps into western MO, where the main risk will be large to very large hail given steep lapse rates aloft and favorable shear. Severe wind gusts will also be possible with these supercells, or any small clusters/bowing segments that can develop where low-level lapse rates are steepest (mainly KS into northwest OK and parts of the OK/TX Panhandles). Some severe threat should persist into the evening as multiple small clusters move southward into southern KS and adjacent portions of far northern OK and southwest MO, before they eventually weaken as convective inhibition increases with nocturnal cooling. ...Great Lakes/Midwest... Additional thunderstorms should develop this afternoon along/near the cold front across parts of Lower MI into central IL. Poor lapse rates aloft and limited low-level moisture (reference 12Z soundings from APX and ILX) will likely temper the degree of instability that can develop, even with diurnal heating. While occasional strong/gusty winds appear possible with thunderstorms that spread east-southeastward this afternoon and evening, the overall severe threat should remain fairly limited. ..Gleason/Lyons.. 09/03/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Wed Sep 03 2025 Valid 031630Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS AND LOWER MISSOURI VALLEY... ...SUMMARY... Scattered thunderstorms capable of producing large to very large hail and severe wind gusts should occur this afternoon and evening across parts of the central Plains and lower Missouri Valley. ...Central Plains into the Lower Missouri Valley... A mid-level shortwave trough over southern SD/eastern NE will continue to advance quickly southeastward today as a large-scale upper-level low moves from western ON to near Lake Superior through the period. The shortwave trough is forecast to reach the lower MO Valley by late afternoon, with an attendant belt of moderately strong northwesterly mid/high-level flow overspreading the central Plains into the mid MS Valley. At the surface, a cold front will advance southward across parts of the central Plains and lower MO Valley, with generally low to mid 60s surface dewpoints present ahead of the boundary. Diurnal heating of this airmass will contribute to moderate instability (MLCAPE around 1000-2000 J/kg) by mid afternoon across central/eastern KS, with weaker instability forecast with eastward extent into MO. As convective inhibition gradually erodes near the front, scattered thunderstorms will likely develop along its length from central KS into the lower MO Valley during the 20-00Z period. Around 35-55 kt of northwesterly flow in the 500-250 mb layer will yield similar values of effective bulk shear, which will support organized updrafts. A few supercells will probably evolve across central/eastern KS and perhaps into western MO, where the main risk will be large to very large hail given steep lapse rates aloft and favorable shear. Severe wind gusts will also be possible with these supercells, or any small clusters/bowing segments that can develop where low-level lapse rates are steepest (mainly KS into northwest OK and parts of the OK/TX Panhandles). Some severe threat should persist into the evening as multiple small clusters move southward into southern KS and adjacent portions of far northern OK and southwest MO, before they eventually weaken as convective inhibition increases with nocturnal cooling. ...Great Lakes/Midwest... Additional thunderstorms should develop this afternoon along/near the cold front across parts of Lower MI into central IL. Poor lapse rates aloft and limited low-level moisture (reference 12Z soundings from APX and ILX) will likely temper the degree of instability that can develop, even with diurnal heating. While occasional strong/gusty winds appear possible with thunderstorms that spread east-southeastward this afternoon and evening, the overall severe threat should remain fairly limited. ..Gleason/Lyons.. 09/03/2025 Read more

5-Day Uncertainty Track last updated Wed, 03 Sep 2025 14:59:57 GMT


Wind Speed Probabilities last updated Wed, 03 Sep 2025 15:26:46 GMT

5-Day Uncertainty Track last updated Wed, 03 Sep 2025 14:59:57 GMT


Wind Speed Probabilities last updated Wed, 03 Sep 2025 14:59:57 GMT

Issued at 800 AM MST Wed Sep 03 2025 000 WTPZ42 KNHC 031458 TCDEP2 Hurricane Lorena Discussion Number 7 NWS National Hurricane Center Miami FL EP122025 800 AM MST Wed Sep 03 2025 Satellite imagery and radar data from the Los Cabos radar in Mexico indicate that Lorena continues to become better organized. Radar imagery shows Lorena's eye becoming better defined, with a completely closed and circular eyewall. Dvorak estimates from TAFB and SAB were both T-4.0/65 kt, with the UW-CIMSS numbers ranging from 55-68 kt. However, the improvement over the last few hours seen in radar images and GOES West satellite images suggest that Lorena is likely stronger now. The initial intensity is estimated at 70 kt, and it is possible this may be a bit conservative. An Air Force Reserve reconnaissance aircraft is currently enroute to Lorena, which should provide a better estimate of the intensity in a couple of hours from now. Lorena has rapidly intensified over the past 24 hours. Continued rapid strengthening is likely for another 12 to 18 hours as Lorena remains over warm water and in low wind shear conditions, and the peak intensity forecast of 85 kt is maintained. By 24 hours, the hurricane is expected to cross the 26C sea-surface temperature isotherm while southwesterly wind shear also begins to significantly increase. These conditions are expected to lead to rapid weakening beginning by Thursday afternoon. The official forecast is above most of the intensity guidance for the first 24 hours, but is closer to the consensus aids thereafter. The initial motion is faster now toward the northwest, or 320/14 kt. Not much has changed with the track forecast reasoning. There are still two camps of models. The majority of the guidance, including the GFS, shows Lorena progressing faster and farther east, with landfall in Baja California Sur followed by a turn toward the northeast. But a significant minority of models, including the ECMWF, CMC, and UKMET, slow down Lorena immediately, with a track farther west, and then dissipate the system over water without making landfall. The steering is such that a stronger cyclone would be more likely to be in the faster and farther east camp of models. However, if the hurricane rapidly weakens by Thursday night and starts to decouple due to the aforementioned increasing southwesterly shear, then the low-level circulation could potentially get left behind. The new NHC forecast shows a faster forward motion over the next 36 hours with a track slightly to the right of the previous NHC track. Due to the rightward shift, the chance of tropical storm force winds impacting portions of Baja California Sur is increasing. Additionally, there is very high confidence that heavy rainfall amounts leading to significant flooding will occur in Baja California Sur, especially since the southwesterly upper-level winds favor deep convection to the right side of Lorena by late Thursday. At 48 h and beyond, the new NHC forecast is similar to, but slightly to the left of, the previous NHC forecast track. Key Messages: 1. Heavy rainfall associated with Tropical Storm Lorena will continue to impact Baja California Sur, moving into southeastern Baja California and southwestern Sonora by Thursday, and contributing to heavy rainfall concerns across Arizona from late Wednesday through Friday. This will increase the risk of life-threatening flash floods and mudslides across Mexico, especially in areas of higher terrain. Isolated to scattered instances of flash flooding are possible across Arizona through Friday. 2. The center of Lorena is forecast to move parallel to, but offshore of, the southwest coast of the Baja Peninsula today, and then move closer to the west-central coast of the peninsula on Thursday. Regardless of the exact track, tropical storm conditions are likely along portions of the coast of Baja California Sur where a Tropical Storm Warning has been issued. Tropical Storm conditions are also possible through tonight along the southwestern coast of Baja California Sur where a Tropical Storm Watch is in effect. Interests elsewhere in Baja California Sur should closely monitor the latest forecast updates. 3. Life-threatening surf and rip current conditions will affect portions of the southern and western coasts of Baja California Sur during the next couple of days. FORECAST POSITIONS AND MAX WINDS INIT 03/1500Z 22.3N 111.6W 70 KT 80 MPH 12H 04/0000Z 23.4N 112.7W 85 KT 100 MPH 24H 04/1200Z 24.5N 113.7W 80 KT 90 MPH 36H 05/0000Z 25.6N 113.9W 65 KT 75 MPH 48H 05/1200Z 26.4N 113.9W 50 KT 60 MPH 60H 06/0000Z 27.5N 113.5W 40 KT 45 MPH 72H 06/1200Z 28.4N 112.8W 35 KT 40 MPH 96H 07/1200Z 30.4N 110.6W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 08/1200Z...DISSIPATED $$ Forecaster Hagen

Issued at 1500 UTC WED SEP 03 2025 000 FOPZ12 KNHC 031455 PWSEP2 HURRICANE LORENA WIND SPEED PROBABILITIES NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL EP122025 1500 UTC WED SEP 03 2025 AT 1500Z THE CENTER OF HURRICANE LORENA WAS LOCATED NEAR LATITUDE 22.3 NORTH...LONGITUDE 111.6 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 70 KTS...80 MPH...130 KM/H. Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH) PACIFIC DAYLIGHT TIME (PDT)...SUBTRACT 7 HOURS FROM Z TIME HAWAIIAN STANDARD TIME (HST)...SUBTRACT 10 HOURS FROM Z TIME WIND SPEED PROBABILITY TABLE FOR SPECIFIC LOCATIONS CHANCES OF SUSTAINED (1-MINUTE AVERAGE) WIND SPEEDS OF AT LEAST ...34 KT (39 MPH... 63 KM/H)... ...50 KT (58 MPH... 93 KM/H)... ...64 KT (74 MPH...119 KM/H)... FOR LOCATIONS AND TIME PERIODS DURING THE NEXT 5 DAYS PROBABILITIES FOR LOCATIONS ARE GIVEN AS OP(CP) WHERE OP IS THE PROBABILITY OF THE EVENT BEGINNING DURING AN INDIVIDUAL TIME PERIOD (ONSET PROBABILITY) (CP) IS THE PROBABILITY OF THE EVENT OCCURRING BETWEEN 12Z WED AND THE FORECAST HOUR (CUMULATIVE PROBABILITY) PROBABILITIES ARE GIVEN IN PERCENT X INDICATES PROBABILITIES LESS THAN 1 PERCENT PROBABILITIES FOR 34 KT AND 50 KT ARE SHOWN AT A GIVEN LOCATION WHEN THE 5-DAY CUMULATIVE PROBABILITY IS AT LEAST 3 PERCENT. PROBABILITIES FOR 34...50...64 KT SHOWN WHEN THE 5-DAY 64-KT CUMULATIVE PROBABILITY IS AT LEAST 1 PERCENT. - - - - WIND SPEED PROBABILITIES FOR SELECTED LOCATIONS - - - - FROM FROM FROM FROM FROM FROM FROM TIME 12Z WED 00Z THU 12Z THU 00Z FRI 12Z FRI 12Z SAT 12Z SUN PERIODS TO TO TO TO TO TO TO 00Z THU 12Z THU 00Z FRI 12Z FRI 12Z SAT 12Z SUN 12Z MON FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT PUNTA EUGENIA 34 X 2( 2) 5( 7) 5(12) 2(14) X(14) X(14) P ABREOJOS 34 X 6( 6) 32(38) 14(52) 5(57) X(57) X(57) P ABREOJOS 50 X 1( 1) 7( 8) 6(14) 2(16) X(16) X(16) P ABREOJOS 64 X X( X) 2( 2) 2( 4) X( 4) X( 4) X( 4) CABO SAN LUCAS 34 1 1( 2) 2( 4) X( 4) X( 4) X( 4) X( 4) SAN JOSE CABO 34 1 1( 2) 2( 4) X( 4) X( 4) X( 4) X( 4) LA PAZ 34 1 2( 3) 2( 5) 1( 6) X( 6) X( 6) X( 6) LORETO 34 1 3( 4) 5( 9) 2(11) 1(12) X(12) X(12) BAHIA KINO 34 X 2( 2) 1( 3) 2( 5) 7(12) X(12) X(12) GUAYMAS 34 X 2( 2) 1( 3) 1( 4) 3( 7) X( 7) X( 7) 25N 115W 34 1 32(33) 17(50) 1(51) X(51) X(51) X(51) 25N 115W 50 X 4( 4) 5( 9) 1(10) X(10) X(10) X(10) 25N 115W 64 X 1( 1) 1( 2) X( 2) X( 2) X( 2) X( 2) $$ FORECASTER HAGEN