Severe Storms

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0333 PM CDT Thu Sep 12 2024 Valid 141200Z - 201200Z In general, fire weather concerns will be on a downward trend across most areas. Upper-level zonal flow will begin to amplify this weekend. A series of troughs will impact the West while ridging will generally remain across the East through the period. Precipitation and cooler temperatures over a broad area of what have been dry fuels should moderate the fire environment for many areas west of the Divide and into some of the Plains. ...Great Basin... As the trough approaches the region this weekend into early next week, some areas of dry and windy conditions are possible both along the Sierra Front as well as into the southern/eastern Basin. Ongoing large fire activity near the Sierra could experience stronger winds, but RH may also be higher along with the winds on Sunday. Further complicating the forecast, cooler temperatures and precipitation along with the initial weekend trough and another trough by the middle of next week will reduce fire weather concerns. These areas will continue to be monitored, but the overall pattern suggests critical fire weather potential is too low for highlights at this time. ...Plains... With troughing expected in the West, troughing along the Rockies is expected to persist into at least the middle of next week. Winds across the Plains may increase periodically as the trough/surface lows intensify. At present, the strongest winds are expected on Tuesday when the initial trough ejects into the central/northern Plains. While there are dry fine fuels in place in some areas, there is also precipitation possible. Unlike the previous southerly flow from the last several days, greater surface moisture will already be present and will likely increase to some degree with the persistent flow from the open Gulf. That said, it is not clear where the greatest fire weather concerns will develop. Trends will continue to be monitored in the coming days. ..Wendt.. 09/12/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0333 PM CDT Thu Sep 12 2024 Valid 141200Z - 201200Z In general, fire weather concerns will be on a downward trend across most areas. Upper-level zonal flow will begin to amplify this weekend. A series of troughs will impact the West while ridging will generally remain across the East through the period. Precipitation and cooler temperatures over a broad area of what have been dry fuels should moderate the fire environment for many areas west of the Divide and into some of the Plains. ...Great Basin... As the trough approaches the region this weekend into early next week, some areas of dry and windy conditions are possible both along the Sierra Front as well as into the southern/eastern Basin. Ongoing large fire activity near the Sierra could experience stronger winds, but RH may also be higher along with the winds on Sunday. Further complicating the forecast, cooler temperatures and precipitation along with the initial weekend trough and another trough by the middle of next week will reduce fire weather concerns. These areas will continue to be monitored, but the overall pattern suggests critical fire weather potential is too low for highlights at this time. ...Plains... With troughing expected in the West, troughing along the Rockies is expected to persist into at least the middle of next week. Winds across the Plains may increase periodically as the trough/surface lows intensify. At present, the strongest winds are expected on Tuesday when the initial trough ejects into the central/northern Plains. While there are dry fine fuels in place in some areas, there is also precipitation possible. Unlike the previous southerly flow from the last several days, greater surface moisture will already be present and will likely increase to some degree with the persistent flow from the open Gulf. That said, it is not clear where the greatest fire weather concerns will develop. Trends will continue to be monitored in the coming days. ..Wendt.. 09/12/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0333 PM CDT Thu Sep 12 2024 Valid 141200Z - 201200Z In general, fire weather concerns will be on a downward trend across most areas. Upper-level zonal flow will begin to amplify this weekend. A series of troughs will impact the West while ridging will generally remain across the East through the period. Precipitation and cooler temperatures over a broad area of what have been dry fuels should moderate the fire environment for many areas west of the Divide and into some of the Plains. ...Great Basin... As the trough approaches the region this weekend into early next week, some areas of dry and windy conditions are possible both along the Sierra Front as well as into the southern/eastern Basin. Ongoing large fire activity near the Sierra could experience stronger winds, but RH may also be higher along with the winds on Sunday. Further complicating the forecast, cooler temperatures and precipitation along with the initial weekend trough and another trough by the middle of next week will reduce fire weather concerns. These areas will continue to be monitored, but the overall pattern suggests critical fire weather potential is too low for highlights at this time. ...Plains... With troughing expected in the West, troughing along the Rockies is expected to persist into at least the middle of next week. Winds across the Plains may increase periodically as the trough/surface lows intensify. At present, the strongest winds are expected on Tuesday when the initial trough ejects into the central/northern Plains. While there are dry fine fuels in place in some areas, there is also precipitation possible. Unlike the previous southerly flow from the last several days, greater surface moisture will already be present and will likely increase to some degree with the persistent flow from the open Gulf. That said, it is not clear where the greatest fire weather concerns will develop. Trends will continue to be monitored in the coming days. ..Wendt.. 09/12/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0333 PM CDT Thu Sep 12 2024 Valid 141200Z - 201200Z In general, fire weather concerns will be on a downward trend across most areas. Upper-level zonal flow will begin to amplify this weekend. A series of troughs will impact the West while ridging will generally remain across the East through the period. Precipitation and cooler temperatures over a broad area of what have been dry fuels should moderate the fire environment for many areas west of the Divide and into some of the Plains. ...Great Basin... As the trough approaches the region this weekend into early next week, some areas of dry and windy conditions are possible both along the Sierra Front as well as into the southern/eastern Basin. Ongoing large fire activity near the Sierra could experience stronger winds, but RH may also be higher along with the winds on Sunday. Further complicating the forecast, cooler temperatures and precipitation along with the initial weekend trough and another trough by the middle of next week will reduce fire weather concerns. These areas will continue to be monitored, but the overall pattern suggests critical fire weather potential is too low for highlights at this time. ...Plains... With troughing expected in the West, troughing along the Rockies is expected to persist into at least the middle of next week. Winds across the Plains may increase periodically as the trough/surface lows intensify. At present, the strongest winds are expected on Tuesday when the initial trough ejects into the central/northern Plains. While there are dry fine fuels in place in some areas, there is also precipitation possible. Unlike the previous southerly flow from the last several days, greater surface moisture will already be present and will likely increase to some degree with the persistent flow from the open Gulf. That said, it is not clear where the greatest fire weather concerns will develop. Trends will continue to be monitored in the coming days. ..Wendt.. 09/12/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0333 PM CDT Thu Sep 12 2024 Valid 141200Z - 201200Z In general, fire weather concerns will be on a downward trend across most areas. Upper-level zonal flow will begin to amplify this weekend. A series of troughs will impact the West while ridging will generally remain across the East through the period. Precipitation and cooler temperatures over a broad area of what have been dry fuels should moderate the fire environment for many areas west of the Divide and into some of the Plains. ...Great Basin... As the trough approaches the region this weekend into early next week, some areas of dry and windy conditions are possible both along the Sierra Front as well as into the southern/eastern Basin. Ongoing large fire activity near the Sierra could experience stronger winds, but RH may also be higher along with the winds on Sunday. Further complicating the forecast, cooler temperatures and precipitation along with the initial weekend trough and another trough by the middle of next week will reduce fire weather concerns. These areas will continue to be monitored, but the overall pattern suggests critical fire weather potential is too low for highlights at this time. ...Plains... With troughing expected in the West, troughing along the Rockies is expected to persist into at least the middle of next week. Winds across the Plains may increase periodically as the trough/surface lows intensify. At present, the strongest winds are expected on Tuesday when the initial trough ejects into the central/northern Plains. While there are dry fine fuels in place in some areas, there is also precipitation possible. Unlike the previous southerly flow from the last several days, greater surface moisture will already be present and will likely increase to some degree with the persistent flow from the open Gulf. That said, it is not clear where the greatest fire weather concerns will develop. Trends will continue to be monitored in the coming days. ..Wendt.. 09/12/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0333 PM CDT Thu Sep 12 2024 Valid 141200Z - 201200Z In general, fire weather concerns will be on a downward trend across most areas. Upper-level zonal flow will begin to amplify this weekend. A series of troughs will impact the West while ridging will generally remain across the East through the period. Precipitation and cooler temperatures over a broad area of what have been dry fuels should moderate the fire environment for many areas west of the Divide and into some of the Plains. ...Great Basin... As the trough approaches the region this weekend into early next week, some areas of dry and windy conditions are possible both along the Sierra Front as well as into the southern/eastern Basin. Ongoing large fire activity near the Sierra could experience stronger winds, but RH may also be higher along with the winds on Sunday. Further complicating the forecast, cooler temperatures and precipitation along with the initial weekend trough and another trough by the middle of next week will reduce fire weather concerns. These areas will continue to be monitored, but the overall pattern suggests critical fire weather potential is too low for highlights at this time. ...Plains... With troughing expected in the West, troughing along the Rockies is expected to persist into at least the middle of next week. Winds across the Plains may increase periodically as the trough/surface lows intensify. At present, the strongest winds are expected on Tuesday when the initial trough ejects into the central/northern Plains. While there are dry fine fuels in place in some areas, there is also precipitation possible. Unlike the previous southerly flow from the last several days, greater surface moisture will already be present and will likely increase to some degree with the persistent flow from the open Gulf. That said, it is not clear where the greatest fire weather concerns will develop. Trends will continue to be monitored in the coming days. ..Wendt.. 09/12/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0333 PM CDT Thu Sep 12 2024 Valid 141200Z - 201200Z In general, fire weather concerns will be on a downward trend across most areas. Upper-level zonal flow will begin to amplify this weekend. A series of troughs will impact the West while ridging will generally remain across the East through the period. Precipitation and cooler temperatures over a broad area of what have been dry fuels should moderate the fire environment for many areas west of the Divide and into some of the Plains. ...Great Basin... As the trough approaches the region this weekend into early next week, some areas of dry and windy conditions are possible both along the Sierra Front as well as into the southern/eastern Basin. Ongoing large fire activity near the Sierra could experience stronger winds, but RH may also be higher along with the winds on Sunday. Further complicating the forecast, cooler temperatures and precipitation along with the initial weekend trough and another trough by the middle of next week will reduce fire weather concerns. These areas will continue to be monitored, but the overall pattern suggests critical fire weather potential is too low for highlights at this time. ...Plains... With troughing expected in the West, troughing along the Rockies is expected to persist into at least the middle of next week. Winds across the Plains may increase periodically as the trough/surface lows intensify. At present, the strongest winds are expected on Tuesday when the initial trough ejects into the central/northern Plains. While there are dry fine fuels in place in some areas, there is also precipitation possible. Unlike the previous southerly flow from the last several days, greater surface moisture will already be present and will likely increase to some degree with the persistent flow from the open Gulf. That said, it is not clear where the greatest fire weather concerns will develop. Trends will continue to be monitored in the coming days. ..Wendt.. 09/12/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0333 PM CDT Thu Sep 12 2024 Valid 141200Z - 201200Z In general, fire weather concerns will be on a downward trend across most areas. Upper-level zonal flow will begin to amplify this weekend. A series of troughs will impact the West while ridging will generally remain across the East through the period. Precipitation and cooler temperatures over a broad area of what have been dry fuels should moderate the fire environment for many areas west of the Divide and into some of the Plains. ...Great Basin... As the trough approaches the region this weekend into early next week, some areas of dry and windy conditions are possible both along the Sierra Front as well as into the southern/eastern Basin. Ongoing large fire activity near the Sierra could experience stronger winds, but RH may also be higher along with the winds on Sunday. Further complicating the forecast, cooler temperatures and precipitation along with the initial weekend trough and another trough by the middle of next week will reduce fire weather concerns. These areas will continue to be monitored, but the overall pattern suggests critical fire weather potential is too low for highlights at this time. ...Plains... With troughing expected in the West, troughing along the Rockies is expected to persist into at least the middle of next week. Winds across the Plains may increase periodically as the trough/surface lows intensify. At present, the strongest winds are expected on Tuesday when the initial trough ejects into the central/northern Plains. While there are dry fine fuels in place in some areas, there is also precipitation possible. Unlike the previous southerly flow from the last several days, greater surface moisture will already be present and will likely increase to some degree with the persistent flow from the open Gulf. That said, it is not clear where the greatest fire weather concerns will develop. Trends will continue to be monitored in the coming days. ..Wendt.. 09/12/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 2060 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR NORTHERN WYOMING INTO EASTERN MONTANA
Mesoscale Discussion 2060 NWS Storm Prediction Center Norman OK 0112 PM CDT Thu Sep 12 2024 Areas affected...Northern Wyoming into eastern Montana Concerning...Severe potential...Watch likely Valid 121812Z - 122015Z Probability of Watch Issuance...80 percent SUMMARY...Organized thunderstorms are expected to increase in coverage and intensity through the afternoon and evening posing a threat of large hail and damaging wind. A severe thunderstorm watch is likely in the next couple of hours. DISCUSSION...An upper-level jet max evident in water-vapor imagery is currently nosing into southern Montana. The large-scale ascent associated with the approaching upper-level trough is encouraging early thunderstorm initiation in northern Wyoming. Although this development is preceding peak diurnal heating, strong forcing is likely to encourage maintenance and additional development over the next few hours. Continued destabilization across eastern Montana will result in a modestly unstable environment (~1000 J/kg MUCAPE) this afternoon with favorable deep-layer shear (~50 knots) characterized by long, straight hodographs. Convection-allowing models suggest that storms will initially be supercellular posing a threat for severe hail and isolated wind gusts. Over time, the storms are expected to evolve into hybrid bowing clusters as they move to the north-northeast. Eventually, storms are expected to grow upscale further posing a threat for severe winds, including the potential for significant severe gusts (i.e., 65 knots). Thus, a severe thunderstorm watch is likely to address this threat. ..Jirak/Guyer.. 09/12/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...UNR...BYZ...GGW...RIW... LAT...LON 44740870 45980793 46840743 47370657 47510543 47250477 46900428 46190419 45410441 44760524 44270601 43650779 43920852 44740870 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 12 2024 Valid 122000Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHEAST... ...SUMMARY... A few tornadoes are possible today from northern Florida to north-central Alabama. Scattered large hail and severe wind gusts (some significant) are expected across eastern Montana into western North Dakota this afternoon through early/mid-evening. ...20z... The D1 Convective Outlook remains on track with no updates needed. A narrow corridor of tornado risk associated with Tropical Depression Francine and the mid/upper low across the southeast will continue across central/southern Alabama this afternoon and evening. See MCD#2061 for more information. Across the northern Great Plains, potential for significant damaging winds will increase through the afternoon and evening as ongoing convection across Montana and Wyoming increases in coverage and tend to grow upscale through the evening. See previous discussion for more information on this threat. ..Thornton.. 09/12/2024 .PREV DISCUSSION... /ISSUED 1138 AM CDT Thu Sep 12 2024/ ...Northern Great Plains including eastern MT/western ND... Have upgraded portions of eastern Montana and western North Dakota for a heightened/focused potential for severe storms capable of large hail and potentially significant-caliber severe wind gusts later this afternoon through around mid-evening. Strong-severe thunderstorms are expected, along and behind the front, as early as early/mid-afternoon, with the most probable severe potential arising from activity moving north-northeastward from northern Wyoming and far southern Montana. High-based supercells and multicells are possible, offering large hail and severe wind gusts. These storms may aggregate and grow upscale into one or two bowing clusters, racing north-northeastward accompanied by a swath of better-organized, potentially significant (65+ kt) gust potential. This scenario will be supported by trough-related cooling mid-level temperatures and steep low/mid-level rates atop a modestly moist boundary layer, as the exit region of a strong upper-level jet overspreads the region. MLCAPE of 500-1200 J/kg and 45-55 kt effective-shear magnitudes will support the severe potential including fast-moving and relatively long-lived storms into western North Dakota. The near-surface airmass over the central Dakotas should stabilize with time and eastward extent tonight, limiting duration and eastward shift of the threat. ...Southeast... Current Tropical Depression Francine is forecast to continue moving generally northward over Mississippi, and to lose definition as it interacts more closely with the mid/upper-level low. Associated deep-layer winds will continue to weaken, but low-level shear will remain favorable through most of the day, well to the east-southeast of its center. A destabilizing airmass along and south of the warm/marine front will support a continued, slow inland shift of supercell potential amid enlarged hodographs. The favorable environment will be bounded on the west by a dry slot and veering low-level flow, on the northeast by more stable air in heavy precip north of the front, and on the south by a gradual weakening of low-level winds and shear as the cyclone center pulls away and fills. In the favorable corridor, where inflow parcels are surface-based, expect effective SRH in the 200-500 m2/s2 range, very rich moisture, low LCL, and weak MLCINH. In the shorter term, a tornado threat may persist this afternoon across northern Florida, while potentially increasing later this afternoon through early evening near the warm front across southern into central Alabama. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 12 2024 Valid 122000Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHEAST... ...SUMMARY... A few tornadoes are possible today from northern Florida to north-central Alabama. Scattered large hail and severe wind gusts (some significant) are expected across eastern Montana into western North Dakota this afternoon through early/mid-evening. ...20z... The D1 Convective Outlook remains on track with no updates needed. A narrow corridor of tornado risk associated with Tropical Depression Francine and the mid/upper low across the southeast will continue across central/southern Alabama this afternoon and evening. See MCD#2061 for more information. Across the northern Great Plains, potential for significant damaging winds will increase through the afternoon and evening as ongoing convection across Montana and Wyoming increases in coverage and tend to grow upscale through the evening. See previous discussion for more information on this threat. ..Thornton.. 09/12/2024 .PREV DISCUSSION... /ISSUED 1138 AM CDT Thu Sep 12 2024/ ...Northern Great Plains including eastern MT/western ND... Have upgraded portions of eastern Montana and western North Dakota for a heightened/focused potential for severe storms capable of large hail and potentially significant-caliber severe wind gusts later this afternoon through around mid-evening. Strong-severe thunderstorms are expected, along and behind the front, as early as early/mid-afternoon, with the most probable severe potential arising from activity moving north-northeastward from northern Wyoming and far southern Montana. High-based supercells and multicells are possible, offering large hail and severe wind gusts. These storms may aggregate and grow upscale into one or two bowing clusters, racing north-northeastward accompanied by a swath of better-organized, potentially significant (65+ kt) gust potential. This scenario will be supported by trough-related cooling mid-level temperatures and steep low/mid-level rates atop a modestly moist boundary layer, as the exit region of a strong upper-level jet overspreads the region. MLCAPE of 500-1200 J/kg and 45-55 kt effective-shear magnitudes will support the severe potential including fast-moving and relatively long-lived storms into western North Dakota. The near-surface airmass over the central Dakotas should stabilize with time and eastward extent tonight, limiting duration and eastward shift of the threat. ...Southeast... Current Tropical Depression Francine is forecast to continue moving generally northward over Mississippi, and to lose definition as it interacts more closely with the mid/upper-level low. Associated deep-layer winds will continue to weaken, but low-level shear will remain favorable through most of the day, well to the east-southeast of its center. A destabilizing airmass along and south of the warm/marine front will support a continued, slow inland shift of supercell potential amid enlarged hodographs. The favorable environment will be bounded on the west by a dry slot and veering low-level flow, on the northeast by more stable air in heavy precip north of the front, and on the south by a gradual weakening of low-level winds and shear as the cyclone center pulls away and fills. In the favorable corridor, where inflow parcels are surface-based, expect effective SRH in the 200-500 m2/s2 range, very rich moisture, low LCL, and weak MLCINH. In the shorter term, a tornado threat may persist this afternoon across northern Florida, while potentially increasing later this afternoon through early evening near the warm front across southern into central Alabama. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 12 2024 Valid 122000Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHEAST... ...SUMMARY... A few tornadoes are possible today from northern Florida to north-central Alabama. Scattered large hail and severe wind gusts (some significant) are expected across eastern Montana into western North Dakota this afternoon through early/mid-evening. ...20z... The D1 Convective Outlook remains on track with no updates needed. A narrow corridor of tornado risk associated with Tropical Depression Francine and the mid/upper low across the southeast will continue across central/southern Alabama this afternoon and evening. See MCD#2061 for more information. Across the northern Great Plains, potential for significant damaging winds will increase through the afternoon and evening as ongoing convection across Montana and Wyoming increases in coverage and tend to grow upscale through the evening. See previous discussion for more information on this threat. ..Thornton.. 09/12/2024 .PREV DISCUSSION... /ISSUED 1138 AM CDT Thu Sep 12 2024/ ...Northern Great Plains including eastern MT/western ND... Have upgraded portions of eastern Montana and western North Dakota for a heightened/focused potential for severe storms capable of large hail and potentially significant-caliber severe wind gusts later this afternoon through around mid-evening. Strong-severe thunderstorms are expected, along and behind the front, as early as early/mid-afternoon, with the most probable severe potential arising from activity moving north-northeastward from northern Wyoming and far southern Montana. High-based supercells and multicells are possible, offering large hail and severe wind gusts. These storms may aggregate and grow upscale into one or two bowing clusters, racing north-northeastward accompanied by a swath of better-organized, potentially significant (65+ kt) gust potential. This scenario will be supported by trough-related cooling mid-level temperatures and steep low/mid-level rates atop a modestly moist boundary layer, as the exit region of a strong upper-level jet overspreads the region. MLCAPE of 500-1200 J/kg and 45-55 kt effective-shear magnitudes will support the severe potential including fast-moving and relatively long-lived storms into western North Dakota. The near-surface airmass over the central Dakotas should stabilize with time and eastward extent tonight, limiting duration and eastward shift of the threat. ...Southeast... Current Tropical Depression Francine is forecast to continue moving generally northward over Mississippi, and to lose definition as it interacts more closely with the mid/upper-level low. Associated deep-layer winds will continue to weaken, but low-level shear will remain favorable through most of the day, well to the east-southeast of its center. A destabilizing airmass along and south of the warm/marine front will support a continued, slow inland shift of supercell potential amid enlarged hodographs. The favorable environment will be bounded on the west by a dry slot and veering low-level flow, on the northeast by more stable air in heavy precip north of the front, and on the south by a gradual weakening of low-level winds and shear as the cyclone center pulls away and fills. In the favorable corridor, where inflow parcels are surface-based, expect effective SRH in the 200-500 m2/s2 range, very rich moisture, low LCL, and weak MLCINH. In the shorter term, a tornado threat may persist this afternoon across northern Florida, while potentially increasing later this afternoon through early evening near the warm front across southern into central Alabama. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 12 2024 Valid 122000Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHEAST... ...SUMMARY... A few tornadoes are possible today from northern Florida to north-central Alabama. Scattered large hail and severe wind gusts (some significant) are expected across eastern Montana into western North Dakota this afternoon through early/mid-evening. ...20z... The D1 Convective Outlook remains on track with no updates needed. A narrow corridor of tornado risk associated with Tropical Depression Francine and the mid/upper low across the southeast will continue across central/southern Alabama this afternoon and evening. See MCD#2061 for more information. Across the northern Great Plains, potential for significant damaging winds will increase through the afternoon and evening as ongoing convection across Montana and Wyoming increases in coverage and tend to grow upscale through the evening. See previous discussion for more information on this threat. ..Thornton.. 09/12/2024 .PREV DISCUSSION... /ISSUED 1138 AM CDT Thu Sep 12 2024/ ...Northern Great Plains including eastern MT/western ND... Have upgraded portions of eastern Montana and western North Dakota for a heightened/focused potential for severe storms capable of large hail and potentially significant-caliber severe wind gusts later this afternoon through around mid-evening. Strong-severe thunderstorms are expected, along and behind the front, as early as early/mid-afternoon, with the most probable severe potential arising from activity moving north-northeastward from northern Wyoming and far southern Montana. High-based supercells and multicells are possible, offering large hail and severe wind gusts. These storms may aggregate and grow upscale into one or two bowing clusters, racing north-northeastward accompanied by a swath of better-organized, potentially significant (65+ kt) gust potential. This scenario will be supported by trough-related cooling mid-level temperatures and steep low/mid-level rates atop a modestly moist boundary layer, as the exit region of a strong upper-level jet overspreads the region. MLCAPE of 500-1200 J/kg and 45-55 kt effective-shear magnitudes will support the severe potential including fast-moving and relatively long-lived storms into western North Dakota. The near-surface airmass over the central Dakotas should stabilize with time and eastward extent tonight, limiting duration and eastward shift of the threat. ...Southeast... Current Tropical Depression Francine is forecast to continue moving generally northward over Mississippi, and to lose definition as it interacts more closely with the mid/upper-level low. Associated deep-layer winds will continue to weaken, but low-level shear will remain favorable through most of the day, well to the east-southeast of its center. A destabilizing airmass along and south of the warm/marine front will support a continued, slow inland shift of supercell potential amid enlarged hodographs. The favorable environment will be bounded on the west by a dry slot and veering low-level flow, on the northeast by more stable air in heavy precip north of the front, and on the south by a gradual weakening of low-level winds and shear as the cyclone center pulls away and fills. In the favorable corridor, where inflow parcels are surface-based, expect effective SRH in the 200-500 m2/s2 range, very rich moisture, low LCL, and weak MLCINH. In the shorter term, a tornado threat may persist this afternoon across northern Florida, while potentially increasing later this afternoon through early evening near the warm front across southern into central Alabama. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 12 2024 Valid 122000Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHEAST... ...SUMMARY... A few tornadoes are possible today from northern Florida to north-central Alabama. Scattered large hail and severe wind gusts (some significant) are expected across eastern Montana into western North Dakota this afternoon through early/mid-evening. ...20z... The D1 Convective Outlook remains on track with no updates needed. A narrow corridor of tornado risk associated with Tropical Depression Francine and the mid/upper low across the southeast will continue across central/southern Alabama this afternoon and evening. See MCD#2061 for more information. Across the northern Great Plains, potential for significant damaging winds will increase through the afternoon and evening as ongoing convection across Montana and Wyoming increases in coverage and tend to grow upscale through the evening. See previous discussion for more information on this threat. ..Thornton.. 09/12/2024 .PREV DISCUSSION... /ISSUED 1138 AM CDT Thu Sep 12 2024/ ...Northern Great Plains including eastern MT/western ND... Have upgraded portions of eastern Montana and western North Dakota for a heightened/focused potential for severe storms capable of large hail and potentially significant-caliber severe wind gusts later this afternoon through around mid-evening. Strong-severe thunderstorms are expected, along and behind the front, as early as early/mid-afternoon, with the most probable severe potential arising from activity moving north-northeastward from northern Wyoming and far southern Montana. High-based supercells and multicells are possible, offering large hail and severe wind gusts. These storms may aggregate and grow upscale into one or two bowing clusters, racing north-northeastward accompanied by a swath of better-organized, potentially significant (65+ kt) gust potential. This scenario will be supported by trough-related cooling mid-level temperatures and steep low/mid-level rates atop a modestly moist boundary layer, as the exit region of a strong upper-level jet overspreads the region. MLCAPE of 500-1200 J/kg and 45-55 kt effective-shear magnitudes will support the severe potential including fast-moving and relatively long-lived storms into western North Dakota. The near-surface airmass over the central Dakotas should stabilize with time and eastward extent tonight, limiting duration and eastward shift of the threat. ...Southeast... Current Tropical Depression Francine is forecast to continue moving generally northward over Mississippi, and to lose definition as it interacts more closely with the mid/upper-level low. Associated deep-layer winds will continue to weaken, but low-level shear will remain favorable through most of the day, well to the east-southeast of its center. A destabilizing airmass along and south of the warm/marine front will support a continued, slow inland shift of supercell potential amid enlarged hodographs. The favorable environment will be bounded on the west by a dry slot and veering low-level flow, on the northeast by more stable air in heavy precip north of the front, and on the south by a gradual weakening of low-level winds and shear as the cyclone center pulls away and fills. In the favorable corridor, where inflow parcels are surface-based, expect effective SRH in the 200-500 m2/s2 range, very rich moisture, low LCL, and weak MLCINH. In the shorter term, a tornado threat may persist this afternoon across northern Florida, while potentially increasing later this afternoon through early evening near the warm front across southern into central Alabama. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 12 2024 Valid 122000Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHEAST... ...SUMMARY... A few tornadoes are possible today from northern Florida to north-central Alabama. Scattered large hail and severe wind gusts (some significant) are expected across eastern Montana into western North Dakota this afternoon through early/mid-evening. ...20z... The D1 Convective Outlook remains on track with no updates needed. A narrow corridor of tornado risk associated with Tropical Depression Francine and the mid/upper low across the southeast will continue across central/southern Alabama this afternoon and evening. See MCD#2061 for more information. Across the northern Great Plains, potential for significant damaging winds will increase through the afternoon and evening as ongoing convection across Montana and Wyoming increases in coverage and tend to grow upscale through the evening. See previous discussion for more information on this threat. ..Thornton.. 09/12/2024 .PREV DISCUSSION... /ISSUED 1138 AM CDT Thu Sep 12 2024/ ...Northern Great Plains including eastern MT/western ND... Have upgraded portions of eastern Montana and western North Dakota for a heightened/focused potential for severe storms capable of large hail and potentially significant-caliber severe wind gusts later this afternoon through around mid-evening. Strong-severe thunderstorms are expected, along and behind the front, as early as early/mid-afternoon, with the most probable severe potential arising from activity moving north-northeastward from northern Wyoming and far southern Montana. High-based supercells and multicells are possible, offering large hail and severe wind gusts. These storms may aggregate and grow upscale into one or two bowing clusters, racing north-northeastward accompanied by a swath of better-organized, potentially significant (65+ kt) gust potential. This scenario will be supported by trough-related cooling mid-level temperatures and steep low/mid-level rates atop a modestly moist boundary layer, as the exit region of a strong upper-level jet overspreads the region. MLCAPE of 500-1200 J/kg and 45-55 kt effective-shear magnitudes will support the severe potential including fast-moving and relatively long-lived storms into western North Dakota. The near-surface airmass over the central Dakotas should stabilize with time and eastward extent tonight, limiting duration and eastward shift of the threat. ...Southeast... Current Tropical Depression Francine is forecast to continue moving generally northward over Mississippi, and to lose definition as it interacts more closely with the mid/upper-level low. Associated deep-layer winds will continue to weaken, but low-level shear will remain favorable through most of the day, well to the east-southeast of its center. A destabilizing airmass along and south of the warm/marine front will support a continued, slow inland shift of supercell potential amid enlarged hodographs. The favorable environment will be bounded on the west by a dry slot and veering low-level flow, on the northeast by more stable air in heavy precip north of the front, and on the south by a gradual weakening of low-level winds and shear as the cyclone center pulls away and fills. In the favorable corridor, where inflow parcels are surface-based, expect effective SRH in the 200-500 m2/s2 range, very rich moisture, low LCL, and weak MLCINH. In the shorter term, a tornado threat may persist this afternoon across northern Florida, while potentially increasing later this afternoon through early evening near the warm front across southern into central Alabama. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 12 2024 Valid 122000Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHEAST... ...SUMMARY... A few tornadoes are possible today from northern Florida to north-central Alabama. Scattered large hail and severe wind gusts (some significant) are expected across eastern Montana into western North Dakota this afternoon through early/mid-evening. ...20z... The D1 Convective Outlook remains on track with no updates needed. A narrow corridor of tornado risk associated with Tropical Depression Francine and the mid/upper low across the southeast will continue across central/southern Alabama this afternoon and evening. See MCD#2061 for more information. Across the northern Great Plains, potential for significant damaging winds will increase through the afternoon and evening as ongoing convection across Montana and Wyoming increases in coverage and tend to grow upscale through the evening. See previous discussion for more information on this threat. ..Thornton.. 09/12/2024 .PREV DISCUSSION... /ISSUED 1138 AM CDT Thu Sep 12 2024/ ...Northern Great Plains including eastern MT/western ND... Have upgraded portions of eastern Montana and western North Dakota for a heightened/focused potential for severe storms capable of large hail and potentially significant-caliber severe wind gusts later this afternoon through around mid-evening. Strong-severe thunderstorms are expected, along and behind the front, as early as early/mid-afternoon, with the most probable severe potential arising from activity moving north-northeastward from northern Wyoming and far southern Montana. High-based supercells and multicells are possible, offering large hail and severe wind gusts. These storms may aggregate and grow upscale into one or two bowing clusters, racing north-northeastward accompanied by a swath of better-organized, potentially significant (65+ kt) gust potential. This scenario will be supported by trough-related cooling mid-level temperatures and steep low/mid-level rates atop a modestly moist boundary layer, as the exit region of a strong upper-level jet overspreads the region. MLCAPE of 500-1200 J/kg and 45-55 kt effective-shear magnitudes will support the severe potential including fast-moving and relatively long-lived storms into western North Dakota. The near-surface airmass over the central Dakotas should stabilize with time and eastward extent tonight, limiting duration and eastward shift of the threat. ...Southeast... Current Tropical Depression Francine is forecast to continue moving generally northward over Mississippi, and to lose definition as it interacts more closely with the mid/upper-level low. Associated deep-layer winds will continue to weaken, but low-level shear will remain favorable through most of the day, well to the east-southeast of its center. A destabilizing airmass along and south of the warm/marine front will support a continued, slow inland shift of supercell potential amid enlarged hodographs. The favorable environment will be bounded on the west by a dry slot and veering low-level flow, on the northeast by more stable air in heavy precip north of the front, and on the south by a gradual weakening of low-level winds and shear as the cyclone center pulls away and fills. In the favorable corridor, where inflow parcels are surface-based, expect effective SRH in the 200-500 m2/s2 range, very rich moisture, low LCL, and weak MLCINH. In the shorter term, a tornado threat may persist this afternoon across northern Florida, while potentially increasing later this afternoon through early evening near the warm front across southern into central Alabama. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 12 2024 Valid 122000Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHEAST... ...SUMMARY... A few tornadoes are possible today from northern Florida to north-central Alabama. Scattered large hail and severe wind gusts (some significant) are expected across eastern Montana into western North Dakota this afternoon through early/mid-evening. ...20z... The D1 Convective Outlook remains on track with no updates needed. A narrow corridor of tornado risk associated with Tropical Depression Francine and the mid/upper low across the southeast will continue across central/southern Alabama this afternoon and evening. See MCD#2061 for more information. Across the northern Great Plains, potential for significant damaging winds will increase through the afternoon and evening as ongoing convection across Montana and Wyoming increases in coverage and tend to grow upscale through the evening. See previous discussion for more information on this threat. ..Thornton.. 09/12/2024 .PREV DISCUSSION... /ISSUED 1138 AM CDT Thu Sep 12 2024/ ...Northern Great Plains including eastern MT/western ND... Have upgraded portions of eastern Montana and western North Dakota for a heightened/focused potential for severe storms capable of large hail and potentially significant-caliber severe wind gusts later this afternoon through around mid-evening. Strong-severe thunderstorms are expected, along and behind the front, as early as early/mid-afternoon, with the most probable severe potential arising from activity moving north-northeastward from northern Wyoming and far southern Montana. High-based supercells and multicells are possible, offering large hail and severe wind gusts. These storms may aggregate and grow upscale into one or two bowing clusters, racing north-northeastward accompanied by a swath of better-organized, potentially significant (65+ kt) gust potential. This scenario will be supported by trough-related cooling mid-level temperatures and steep low/mid-level rates atop a modestly moist boundary layer, as the exit region of a strong upper-level jet overspreads the region. MLCAPE of 500-1200 J/kg and 45-55 kt effective-shear magnitudes will support the severe potential including fast-moving and relatively long-lived storms into western North Dakota. The near-surface airmass over the central Dakotas should stabilize with time and eastward extent tonight, limiting duration and eastward shift of the threat. ...Southeast... Current Tropical Depression Francine is forecast to continue moving generally northward over Mississippi, and to lose definition as it interacts more closely with the mid/upper-level low. Associated deep-layer winds will continue to weaken, but low-level shear will remain favorable through most of the day, well to the east-southeast of its center. A destabilizing airmass along and south of the warm/marine front will support a continued, slow inland shift of supercell potential amid enlarged hodographs. The favorable environment will be bounded on the west by a dry slot and veering low-level flow, on the northeast by more stable air in heavy precip north of the front, and on the south by a gradual weakening of low-level winds and shear as the cyclone center pulls away and fills. In the favorable corridor, where inflow parcels are surface-based, expect effective SRH in the 200-500 m2/s2 range, very rich moisture, low LCL, and weak MLCINH. In the shorter term, a tornado threat may persist this afternoon across northern Florida, while potentially increasing later this afternoon through early evening near the warm front across southern into central Alabama. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 12 2024 Valid 122000Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHEAST... ...SUMMARY... A few tornadoes are possible today from northern Florida to north-central Alabama. Scattered large hail and severe wind gusts (some significant) are expected across eastern Montana into western North Dakota this afternoon through early/mid-evening. ...20z... The D1 Convective Outlook remains on track with no updates needed. A narrow corridor of tornado risk associated with Tropical Depression Francine and the mid/upper low across the southeast will continue across central/southern Alabama this afternoon and evening. See MCD#2061 for more information. Across the northern Great Plains, potential for significant damaging winds will increase through the afternoon and evening as ongoing convection across Montana and Wyoming increases in coverage and tend to grow upscale through the evening. See previous discussion for more information on this threat. ..Thornton.. 09/12/2024 .PREV DISCUSSION... /ISSUED 1138 AM CDT Thu Sep 12 2024/ ...Northern Great Plains including eastern MT/western ND... Have upgraded portions of eastern Montana and western North Dakota for a heightened/focused potential for severe storms capable of large hail and potentially significant-caliber severe wind gusts later this afternoon through around mid-evening. Strong-severe thunderstorms are expected, along and behind the front, as early as early/mid-afternoon, with the most probable severe potential arising from activity moving north-northeastward from northern Wyoming and far southern Montana. High-based supercells and multicells are possible, offering large hail and severe wind gusts. These storms may aggregate and grow upscale into one or two bowing clusters, racing north-northeastward accompanied by a swath of better-organized, potentially significant (65+ kt) gust potential. This scenario will be supported by trough-related cooling mid-level temperatures and steep low/mid-level rates atop a modestly moist boundary layer, as the exit region of a strong upper-level jet overspreads the region. MLCAPE of 500-1200 J/kg and 45-55 kt effective-shear magnitudes will support the severe potential including fast-moving and relatively long-lived storms into western North Dakota. The near-surface airmass over the central Dakotas should stabilize with time and eastward extent tonight, limiting duration and eastward shift of the threat. ...Southeast... Current Tropical Depression Francine is forecast to continue moving generally northward over Mississippi, and to lose definition as it interacts more closely with the mid/upper-level low. Associated deep-layer winds will continue to weaken, but low-level shear will remain favorable through most of the day, well to the east-southeast of its center. A destabilizing airmass along and south of the warm/marine front will support a continued, slow inland shift of supercell potential amid enlarged hodographs. The favorable environment will be bounded on the west by a dry slot and veering low-level flow, on the northeast by more stable air in heavy precip north of the front, and on the south by a gradual weakening of low-level winds and shear as the cyclone center pulls away and fills. In the favorable corridor, where inflow parcels are surface-based, expect effective SRH in the 200-500 m2/s2 range, very rich moisture, low LCL, and weak MLCINH. In the shorter term, a tornado threat may persist this afternoon across northern Florida, while potentially increasing later this afternoon through early evening near the warm front across southern into central Alabama. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 12 2024 Valid 122000Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHEAST... ...SUMMARY... A few tornadoes are possible today from northern Florida to north-central Alabama. Scattered large hail and severe wind gusts (some significant) are expected across eastern Montana into western North Dakota this afternoon through early/mid-evening. ...20z... The D1 Convective Outlook remains on track with no updates needed. A narrow corridor of tornado risk associated with Tropical Depression Francine and the mid/upper low across the southeast will continue across central/southern Alabama this afternoon and evening. See MCD#2061 for more information. Across the northern Great Plains, potential for significant damaging winds will increase through the afternoon and evening as ongoing convection across Montana and Wyoming increases in coverage and tend to grow upscale through the evening. See previous discussion for more information on this threat. ..Thornton.. 09/12/2024 .PREV DISCUSSION... /ISSUED 1138 AM CDT Thu Sep 12 2024/ ...Northern Great Plains including eastern MT/western ND... Have upgraded portions of eastern Montana and western North Dakota for a heightened/focused potential for severe storms capable of large hail and potentially significant-caliber severe wind gusts later this afternoon through around mid-evening. Strong-severe thunderstorms are expected, along and behind the front, as early as early/mid-afternoon, with the most probable severe potential arising from activity moving north-northeastward from northern Wyoming and far southern Montana. High-based supercells and multicells are possible, offering large hail and severe wind gusts. These storms may aggregate and grow upscale into one or two bowing clusters, racing north-northeastward accompanied by a swath of better-organized, potentially significant (65+ kt) gust potential. This scenario will be supported by trough-related cooling mid-level temperatures and steep low/mid-level rates atop a modestly moist boundary layer, as the exit region of a strong upper-level jet overspreads the region. MLCAPE of 500-1200 J/kg and 45-55 kt effective-shear magnitudes will support the severe potential including fast-moving and relatively long-lived storms into western North Dakota. The near-surface airmass over the central Dakotas should stabilize with time and eastward extent tonight, limiting duration and eastward shift of the threat. ...Southeast... Current Tropical Depression Francine is forecast to continue moving generally northward over Mississippi, and to lose definition as it interacts more closely with the mid/upper-level low. Associated deep-layer winds will continue to weaken, but low-level shear will remain favorable through most of the day, well to the east-southeast of its center. A destabilizing airmass along and south of the warm/marine front will support a continued, slow inland shift of supercell potential amid enlarged hodographs. The favorable environment will be bounded on the west by a dry slot and veering low-level flow, on the northeast by more stable air in heavy precip north of the front, and on the south by a gradual weakening of low-level winds and shear as the cyclone center pulls away and fills. In the favorable corridor, where inflow parcels are surface-based, expect effective SRH in the 200-500 m2/s2 range, very rich moisture, low LCL, and weak MLCINH. In the shorter term, a tornado threat may persist this afternoon across northern Florida, while potentially increasing later this afternoon through early evening near the warm front across southern into central Alabama. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 12 2024 Valid 122000Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHEAST... ...SUMMARY... A few tornadoes are possible today from northern Florida to north-central Alabama. Scattered large hail and severe wind gusts (some significant) are expected across eastern Montana into western North Dakota this afternoon through early/mid-evening. ...20z... The D1 Convective Outlook remains on track with no updates needed. A narrow corridor of tornado risk associated with Tropical Depression Francine and the mid/upper low across the southeast will continue across central/southern Alabama this afternoon and evening. See MCD#2061 for more information. Across the northern Great Plains, potential for significant damaging winds will increase through the afternoon and evening as ongoing convection across Montana and Wyoming increases in coverage and tend to grow upscale through the evening. See previous discussion for more information on this threat. ..Thornton.. 09/12/2024 .PREV DISCUSSION... /ISSUED 1138 AM CDT Thu Sep 12 2024/ ...Northern Great Plains including eastern MT/western ND... Have upgraded portions of eastern Montana and western North Dakota for a heightened/focused potential for severe storms capable of large hail and potentially significant-caliber severe wind gusts later this afternoon through around mid-evening. Strong-severe thunderstorms are expected, along and behind the front, as early as early/mid-afternoon, with the most probable severe potential arising from activity moving north-northeastward from northern Wyoming and far southern Montana. High-based supercells and multicells are possible, offering large hail and severe wind gusts. These storms may aggregate and grow upscale into one or two bowing clusters, racing north-northeastward accompanied by a swath of better-organized, potentially significant (65+ kt) gust potential. This scenario will be supported by trough-related cooling mid-level temperatures and steep low/mid-level rates atop a modestly moist boundary layer, as the exit region of a strong upper-level jet overspreads the region. MLCAPE of 500-1200 J/kg and 45-55 kt effective-shear magnitudes will support the severe potential including fast-moving and relatively long-lived storms into western North Dakota. The near-surface airmass over the central Dakotas should stabilize with time and eastward extent tonight, limiting duration and eastward shift of the threat. ...Southeast... Current Tropical Depression Francine is forecast to continue moving generally northward over Mississippi, and to lose definition as it interacts more closely with the mid/upper-level low. Associated deep-layer winds will continue to weaken, but low-level shear will remain favorable through most of the day, well to the east-southeast of its center. A destabilizing airmass along and south of the warm/marine front will support a continued, slow inland shift of supercell potential amid enlarged hodographs. The favorable environment will be bounded on the west by a dry slot and veering low-level flow, on the northeast by more stable air in heavy precip north of the front, and on the south by a gradual weakening of low-level winds and shear as the cyclone center pulls away and fills. In the favorable corridor, where inflow parcels are surface-based, expect effective SRH in the 200-500 m2/s2 range, very rich moisture, low LCL, and weak MLCINH. In the shorter term, a tornado threat may persist this afternoon across northern Florida, while potentially increasing later this afternoon through early evening near the warm front across southern into central Alabama. Read more