Severe Storms

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0740 AM CDT Sat Aug 31 2024 Valid 311300Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL APPALACHIANS AND UPPER OHIO VALLEY... ...SUMMARY... Severe thunderstorms capable of producing mainly damaging winds will be possible today from parts of the central Appalachians into the Ohio and Tennessee Valleys. Isolated severe wind gusts may also occur across parts of the northern Great Lakes. ...Mid-Atlantic into the Ohio and Tennessee Valleys... A mid/upper-level trough will make slow eastward progress today across Ontario/Quebec and the Great Lakes while amplifying further. Ahead of this feature, a surface front should continue to lose definition and weaken through the day as it moves eastward over parts of the Northeast/Mid-Atlantic, and southeastward over the OH Valley before eventually stalling. Recent visible satellite imagery shows cloud cover remains prevalent over much of the Northeast and Mid-Atlantic. This will hinder daytime heating and delay destabilization, especially east of the Blue Ridge Mountains. Still, area 12Z soundings and recent surface observations indicate a moist low-level airmass remains in place ahead of the weak cold front. Generally less cloud cover with westward and southward extent into the upper OH Valley and TN Valley should allow for greater instability to develop this afternoon across these regions. The stronger mid-level flow associated the upper trough is expected to remain generally displaced to the north/west of the surface warm sector. Even so, modestly increasing west-southwesterly winds with height through mid levels should support around 20-30 kt of deep-layer shear across parts of the central Appalachians and upper OH Valley vicinity. This shear will be sufficient for loosely organized multicell clusters to develop and subsequently spread east-southeastward through this afternoon. Isolated to scattered damaging winds should be the main threat with this convection, although some hail may also occur with the strongest cores. Activity should weaken with eastward extent late this afternoon and evening across the Mid-Atlantic as it encounters a less unstable airmass. Weaker deep-layer shear with southward extent into the lower OH Valley and TN Valley will likely limit overall thunderstorm organization. But, occasional damaging winds may still occur with thunderstorms along/south of the front as low-level lapse rates steepen with diurnal heating. ...Northern Great Lakes... Strong west-northwesterly mid-level flow will be present today over the Upper Midwest and northern Great Lakes, in association with a shortwave trough embedded within a larger upper trough moving east-southeastward across these regions. While low-level moisture and related instability are both expected to remain limited, large-scale ascent and strong deep-layer shear may support the development low-topped convection this afternoon. If these thunderstorms can form and be sustained, then isolated strong to severe winds may occur given the forecast strength of the low to mid-level flow amid steepened low-level lapse rates. ..Gleason/Leitman.. 08/31/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0740 AM CDT Sat Aug 31 2024 Valid 311300Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL APPALACHIANS AND UPPER OHIO VALLEY... ...SUMMARY... Severe thunderstorms capable of producing mainly damaging winds will be possible today from parts of the central Appalachians into the Ohio and Tennessee Valleys. Isolated severe wind gusts may also occur across parts of the northern Great Lakes. ...Mid-Atlantic into the Ohio and Tennessee Valleys... A mid/upper-level trough will make slow eastward progress today across Ontario/Quebec and the Great Lakes while amplifying further. Ahead of this feature, a surface front should continue to lose definition and weaken through the day as it moves eastward over parts of the Northeast/Mid-Atlantic, and southeastward over the OH Valley before eventually stalling. Recent visible satellite imagery shows cloud cover remains prevalent over much of the Northeast and Mid-Atlantic. This will hinder daytime heating and delay destabilization, especially east of the Blue Ridge Mountains. Still, area 12Z soundings and recent surface observations indicate a moist low-level airmass remains in place ahead of the weak cold front. Generally less cloud cover with westward and southward extent into the upper OH Valley and TN Valley should allow for greater instability to develop this afternoon across these regions. The stronger mid-level flow associated the upper trough is expected to remain generally displaced to the north/west of the surface warm sector. Even so, modestly increasing west-southwesterly winds with height through mid levels should support around 20-30 kt of deep-layer shear across parts of the central Appalachians and upper OH Valley vicinity. This shear will be sufficient for loosely organized multicell clusters to develop and subsequently spread east-southeastward through this afternoon. Isolated to scattered damaging winds should be the main threat with this convection, although some hail may also occur with the strongest cores. Activity should weaken with eastward extent late this afternoon and evening across the Mid-Atlantic as it encounters a less unstable airmass. Weaker deep-layer shear with southward extent into the lower OH Valley and TN Valley will likely limit overall thunderstorm organization. But, occasional damaging winds may still occur with thunderstorms along/south of the front as low-level lapse rates steepen with diurnal heating. ...Northern Great Lakes... Strong west-northwesterly mid-level flow will be present today over the Upper Midwest and northern Great Lakes, in association with a shortwave trough embedded within a larger upper trough moving east-southeastward across these regions. While low-level moisture and related instability are both expected to remain limited, large-scale ascent and strong deep-layer shear may support the development low-topped convection this afternoon. If these thunderstorms can form and be sustained, then isolated strong to severe winds may occur given the forecast strength of the low to mid-level flow amid steepened low-level lapse rates. ..Gleason/Leitman.. 08/31/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0740 AM CDT Sat Aug 31 2024 Valid 311300Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL APPALACHIANS AND UPPER OHIO VALLEY... ...SUMMARY... Severe thunderstorms capable of producing mainly damaging winds will be possible today from parts of the central Appalachians into the Ohio and Tennessee Valleys. Isolated severe wind gusts may also occur across parts of the northern Great Lakes. ...Mid-Atlantic into the Ohio and Tennessee Valleys... A mid/upper-level trough will make slow eastward progress today across Ontario/Quebec and the Great Lakes while amplifying further. Ahead of this feature, a surface front should continue to lose definition and weaken through the day as it moves eastward over parts of the Northeast/Mid-Atlantic, and southeastward over the OH Valley before eventually stalling. Recent visible satellite imagery shows cloud cover remains prevalent over much of the Northeast and Mid-Atlantic. This will hinder daytime heating and delay destabilization, especially east of the Blue Ridge Mountains. Still, area 12Z soundings and recent surface observations indicate a moist low-level airmass remains in place ahead of the weak cold front. Generally less cloud cover with westward and southward extent into the upper OH Valley and TN Valley should allow for greater instability to develop this afternoon across these regions. The stronger mid-level flow associated the upper trough is expected to remain generally displaced to the north/west of the surface warm sector. Even so, modestly increasing west-southwesterly winds with height through mid levels should support around 20-30 kt of deep-layer shear across parts of the central Appalachians and upper OH Valley vicinity. This shear will be sufficient for loosely organized multicell clusters to develop and subsequently spread east-southeastward through this afternoon. Isolated to scattered damaging winds should be the main threat with this convection, although some hail may also occur with the strongest cores. Activity should weaken with eastward extent late this afternoon and evening across the Mid-Atlantic as it encounters a less unstable airmass. Weaker deep-layer shear with southward extent into the lower OH Valley and TN Valley will likely limit overall thunderstorm organization. But, occasional damaging winds may still occur with thunderstorms along/south of the front as low-level lapse rates steepen with diurnal heating. ...Northern Great Lakes... Strong west-northwesterly mid-level flow will be present today over the Upper Midwest and northern Great Lakes, in association with a shortwave trough embedded within a larger upper trough moving east-southeastward across these regions. While low-level moisture and related instability are both expected to remain limited, large-scale ascent and strong deep-layer shear may support the development low-topped convection this afternoon. If these thunderstorms can form and be sustained, then isolated strong to severe winds may occur given the forecast strength of the low to mid-level flow amid steepened low-level lapse rates. ..Gleason/Leitman.. 08/31/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0740 AM CDT Sat Aug 31 2024 Valid 311300Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL APPALACHIANS AND UPPER OHIO VALLEY... ...SUMMARY... Severe thunderstorms capable of producing mainly damaging winds will be possible today from parts of the central Appalachians into the Ohio and Tennessee Valleys. Isolated severe wind gusts may also occur across parts of the northern Great Lakes. ...Mid-Atlantic into the Ohio and Tennessee Valleys... A mid/upper-level trough will make slow eastward progress today across Ontario/Quebec and the Great Lakes while amplifying further. Ahead of this feature, a surface front should continue to lose definition and weaken through the day as it moves eastward over parts of the Northeast/Mid-Atlantic, and southeastward over the OH Valley before eventually stalling. Recent visible satellite imagery shows cloud cover remains prevalent over much of the Northeast and Mid-Atlantic. This will hinder daytime heating and delay destabilization, especially east of the Blue Ridge Mountains. Still, area 12Z soundings and recent surface observations indicate a moist low-level airmass remains in place ahead of the weak cold front. Generally less cloud cover with westward and southward extent into the upper OH Valley and TN Valley should allow for greater instability to develop this afternoon across these regions. The stronger mid-level flow associated the upper trough is expected to remain generally displaced to the north/west of the surface warm sector. Even so, modestly increasing west-southwesterly winds with height through mid levels should support around 20-30 kt of deep-layer shear across parts of the central Appalachians and upper OH Valley vicinity. This shear will be sufficient for loosely organized multicell clusters to develop and subsequently spread east-southeastward through this afternoon. Isolated to scattered damaging winds should be the main threat with this convection, although some hail may also occur with the strongest cores. Activity should weaken with eastward extent late this afternoon and evening across the Mid-Atlantic as it encounters a less unstable airmass. Weaker deep-layer shear with southward extent into the lower OH Valley and TN Valley will likely limit overall thunderstorm organization. But, occasional damaging winds may still occur with thunderstorms along/south of the front as low-level lapse rates steepen with diurnal heating. ...Northern Great Lakes... Strong west-northwesterly mid-level flow will be present today over the Upper Midwest and northern Great Lakes, in association with a shortwave trough embedded within a larger upper trough moving east-southeastward across these regions. While low-level moisture and related instability are both expected to remain limited, large-scale ascent and strong deep-layer shear may support the development low-topped convection this afternoon. If these thunderstorms can form and be sustained, then isolated strong to severe winds may occur given the forecast strength of the low to mid-level flow amid steepened low-level lapse rates. ..Gleason/Leitman.. 08/31/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0740 AM CDT Sat Aug 31 2024 Valid 311300Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL APPALACHIANS AND UPPER OHIO VALLEY... ...SUMMARY... Severe thunderstorms capable of producing mainly damaging winds will be possible today from parts of the central Appalachians into the Ohio and Tennessee Valleys. Isolated severe wind gusts may also occur across parts of the northern Great Lakes. ...Mid-Atlantic into the Ohio and Tennessee Valleys... A mid/upper-level trough will make slow eastward progress today across Ontario/Quebec and the Great Lakes while amplifying further. Ahead of this feature, a surface front should continue to lose definition and weaken through the day as it moves eastward over parts of the Northeast/Mid-Atlantic, and southeastward over the OH Valley before eventually stalling. Recent visible satellite imagery shows cloud cover remains prevalent over much of the Northeast and Mid-Atlantic. This will hinder daytime heating and delay destabilization, especially east of the Blue Ridge Mountains. Still, area 12Z soundings and recent surface observations indicate a moist low-level airmass remains in place ahead of the weak cold front. Generally less cloud cover with westward and southward extent into the upper OH Valley and TN Valley should allow for greater instability to develop this afternoon across these regions. The stronger mid-level flow associated the upper trough is expected to remain generally displaced to the north/west of the surface warm sector. Even so, modestly increasing west-southwesterly winds with height through mid levels should support around 20-30 kt of deep-layer shear across parts of the central Appalachians and upper OH Valley vicinity. This shear will be sufficient for loosely organized multicell clusters to develop and subsequently spread east-southeastward through this afternoon. Isolated to scattered damaging winds should be the main threat with this convection, although some hail may also occur with the strongest cores. Activity should weaken with eastward extent late this afternoon and evening across the Mid-Atlantic as it encounters a less unstable airmass. Weaker deep-layer shear with southward extent into the lower OH Valley and TN Valley will likely limit overall thunderstorm organization. But, occasional damaging winds may still occur with thunderstorms along/south of the front as low-level lapse rates steepen with diurnal heating. ...Northern Great Lakes... Strong west-northwesterly mid-level flow will be present today over the Upper Midwest and northern Great Lakes, in association with a shortwave trough embedded within a larger upper trough moving east-southeastward across these regions. While low-level moisture and related instability are both expected to remain limited, large-scale ascent and strong deep-layer shear may support the development low-topped convection this afternoon. If these thunderstorms can form and be sustained, then isolated strong to severe winds may occur given the forecast strength of the low to mid-level flow amid steepened low-level lapse rates. ..Gleason/Leitman.. 08/31/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0740 AM CDT Sat Aug 31 2024 Valid 311300Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL APPALACHIANS AND UPPER OHIO VALLEY... ...SUMMARY... Severe thunderstorms capable of producing mainly damaging winds will be possible today from parts of the central Appalachians into the Ohio and Tennessee Valleys. Isolated severe wind gusts may also occur across parts of the northern Great Lakes. ...Mid-Atlantic into the Ohio and Tennessee Valleys... A mid/upper-level trough will make slow eastward progress today across Ontario/Quebec and the Great Lakes while amplifying further. Ahead of this feature, a surface front should continue to lose definition and weaken through the day as it moves eastward over parts of the Northeast/Mid-Atlantic, and southeastward over the OH Valley before eventually stalling. Recent visible satellite imagery shows cloud cover remains prevalent over much of the Northeast and Mid-Atlantic. This will hinder daytime heating and delay destabilization, especially east of the Blue Ridge Mountains. Still, area 12Z soundings and recent surface observations indicate a moist low-level airmass remains in place ahead of the weak cold front. Generally less cloud cover with westward and southward extent into the upper OH Valley and TN Valley should allow for greater instability to develop this afternoon across these regions. The stronger mid-level flow associated the upper trough is expected to remain generally displaced to the north/west of the surface warm sector. Even so, modestly increasing west-southwesterly winds with height through mid levels should support around 20-30 kt of deep-layer shear across parts of the central Appalachians and upper OH Valley vicinity. This shear will be sufficient for loosely organized multicell clusters to develop and subsequently spread east-southeastward through this afternoon. Isolated to scattered damaging winds should be the main threat with this convection, although some hail may also occur with the strongest cores. Activity should weaken with eastward extent late this afternoon and evening across the Mid-Atlantic as it encounters a less unstable airmass. Weaker deep-layer shear with southward extent into the lower OH Valley and TN Valley will likely limit overall thunderstorm organization. But, occasional damaging winds may still occur with thunderstorms along/south of the front as low-level lapse rates steepen with diurnal heating. ...Northern Great Lakes... Strong west-northwesterly mid-level flow will be present today over the Upper Midwest and northern Great Lakes, in association with a shortwave trough embedded within a larger upper trough moving east-southeastward across these regions. While low-level moisture and related instability are both expected to remain limited, large-scale ascent and strong deep-layer shear may support the development low-topped convection this afternoon. If these thunderstorms can form and be sustained, then isolated strong to severe winds may occur given the forecast strength of the low to mid-level flow amid steepened low-level lapse rates. ..Gleason/Leitman.. 08/31/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0333 AM CDT Sat Aug 31 2024 Valid 031200Z - 081200Z ...DISCUSSION... Global models are in reasonable agreement with handling of large-scale features through about Day 5/Wednesday, after which divergent tendencies become apparent -- particularly with the handling of a weak short-wave feature moving across the northwestern U.S. early in the period. Models depict this feature partially phasing with a more substantial trough moving across western Canada within the faster belt of westerlies to the north Day 4/Tuesday, and then emerging into the north-central U.S. Day 5. Afterward, evolution of this trough begins to differ substantially amongst the models. The GFS depicts this trough evolving into cut-off low over the Upper Mississippi Valley/Upper Great Lakes region Day 6/Thursday, which then lingers in place through Day 8 and beyond. Meanwhile, the ECMWF remains slowly progressive with the trough into eastern North America through the period. Given these substantial differences, convective/severe potential cannot be reasonably assessed beyond Day 5. In the Day 4-5 time frame, a cold-frontal advance out of the western U.S. into the northern Plains -- and eventually the Great Lakes region -- is expected, in tandem with the progression of the aforementioned upper trough. However, with a surface high still firmly in place from the eastern U.S. westward into the central/southern Plains, Gulf moisture will remain suppressed, and thus the likelihood for only meager destabilization across the pre-frontal warm sector. Therefore, severe risk is expected to remain limited, thus not requiring a 15% areal outline associated with this system through Day 5. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0333 AM CDT Sat Aug 31 2024 Valid 031200Z - 081200Z ...DISCUSSION... Global models are in reasonable agreement with handling of large-scale features through about Day 5/Wednesday, after which divergent tendencies become apparent -- particularly with the handling of a weak short-wave feature moving across the northwestern U.S. early in the period. Models depict this feature partially phasing with a more substantial trough moving across western Canada within the faster belt of westerlies to the north Day 4/Tuesday, and then emerging into the north-central U.S. Day 5. Afterward, evolution of this trough begins to differ substantially amongst the models. The GFS depicts this trough evolving into cut-off low over the Upper Mississippi Valley/Upper Great Lakes region Day 6/Thursday, which then lingers in place through Day 8 and beyond. Meanwhile, the ECMWF remains slowly progressive with the trough into eastern North America through the period. Given these substantial differences, convective/severe potential cannot be reasonably assessed beyond Day 5. In the Day 4-5 time frame, a cold-frontal advance out of the western U.S. into the northern Plains -- and eventually the Great Lakes region -- is expected, in tandem with the progression of the aforementioned upper trough. However, with a surface high still firmly in place from the eastern U.S. westward into the central/southern Plains, Gulf moisture will remain suppressed, and thus the likelihood for only meager destabilization across the pre-frontal warm sector. Therefore, severe risk is expected to remain limited, thus not requiring a 15% areal outline associated with this system through Day 5. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0333 AM CDT Sat Aug 31 2024 Valid 031200Z - 081200Z ...DISCUSSION... Global models are in reasonable agreement with handling of large-scale features through about Day 5/Wednesday, after which divergent tendencies become apparent -- particularly with the handling of a weak short-wave feature moving across the northwestern U.S. early in the period. Models depict this feature partially phasing with a more substantial trough moving across western Canada within the faster belt of westerlies to the north Day 4/Tuesday, and then emerging into the north-central U.S. Day 5. Afterward, evolution of this trough begins to differ substantially amongst the models. The GFS depicts this trough evolving into cut-off low over the Upper Mississippi Valley/Upper Great Lakes region Day 6/Thursday, which then lingers in place through Day 8 and beyond. Meanwhile, the ECMWF remains slowly progressive with the trough into eastern North America through the period. Given these substantial differences, convective/severe potential cannot be reasonably assessed beyond Day 5. In the Day 4-5 time frame, a cold-frontal advance out of the western U.S. into the northern Plains -- and eventually the Great Lakes region -- is expected, in tandem with the progression of the aforementioned upper trough. However, with a surface high still firmly in place from the eastern U.S. westward into the central/southern Plains, Gulf moisture will remain suppressed, and thus the likelihood for only meager destabilization across the pre-frontal warm sector. Therefore, severe risk is expected to remain limited, thus not requiring a 15% areal outline associated with this system through Day 5. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0333 AM CDT Sat Aug 31 2024 Valid 031200Z - 081200Z ...DISCUSSION... Global models are in reasonable agreement with handling of large-scale features through about Day 5/Wednesday, after which divergent tendencies become apparent -- particularly with the handling of a weak short-wave feature moving across the northwestern U.S. early in the period. Models depict this feature partially phasing with a more substantial trough moving across western Canada within the faster belt of westerlies to the north Day 4/Tuesday, and then emerging into the north-central U.S. Day 5. Afterward, evolution of this trough begins to differ substantially amongst the models. The GFS depicts this trough evolving into cut-off low over the Upper Mississippi Valley/Upper Great Lakes region Day 6/Thursday, which then lingers in place through Day 8 and beyond. Meanwhile, the ECMWF remains slowly progressive with the trough into eastern North America through the period. Given these substantial differences, convective/severe potential cannot be reasonably assessed beyond Day 5. In the Day 4-5 time frame, a cold-frontal advance out of the western U.S. into the northern Plains -- and eventually the Great Lakes region -- is expected, in tandem with the progression of the aforementioned upper trough. However, with a surface high still firmly in place from the eastern U.S. westward into the central/southern Plains, Gulf moisture will remain suppressed, and thus the likelihood for only meager destabilization across the pre-frontal warm sector. Therefore, severe risk is expected to remain limited, thus not requiring a 15% areal outline associated with this system through Day 5. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0333 AM CDT Sat Aug 31 2024 Valid 031200Z - 081200Z ...DISCUSSION... Global models are in reasonable agreement with handling of large-scale features through about Day 5/Wednesday, after which divergent tendencies become apparent -- particularly with the handling of a weak short-wave feature moving across the northwestern U.S. early in the period. Models depict this feature partially phasing with a more substantial trough moving across western Canada within the faster belt of westerlies to the north Day 4/Tuesday, and then emerging into the north-central U.S. Day 5. Afterward, evolution of this trough begins to differ substantially amongst the models. The GFS depicts this trough evolving into cut-off low over the Upper Mississippi Valley/Upper Great Lakes region Day 6/Thursday, which then lingers in place through Day 8 and beyond. Meanwhile, the ECMWF remains slowly progressive with the trough into eastern North America through the period. Given these substantial differences, convective/severe potential cannot be reasonably assessed beyond Day 5. In the Day 4-5 time frame, a cold-frontal advance out of the western U.S. into the northern Plains -- and eventually the Great Lakes region -- is expected, in tandem with the progression of the aforementioned upper trough. However, with a surface high still firmly in place from the eastern U.S. westward into the central/southern Plains, Gulf moisture will remain suppressed, and thus the likelihood for only meager destabilization across the pre-frontal warm sector. Therefore, severe risk is expected to remain limited, thus not requiring a 15% areal outline associated with this system through Day 5. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0333 AM CDT Sat Aug 31 2024 Valid 031200Z - 081200Z ...DISCUSSION... Global models are in reasonable agreement with handling of large-scale features through about Day 5/Wednesday, after which divergent tendencies become apparent -- particularly with the handling of a weak short-wave feature moving across the northwestern U.S. early in the period. Models depict this feature partially phasing with a more substantial trough moving across western Canada within the faster belt of westerlies to the north Day 4/Tuesday, and then emerging into the north-central U.S. Day 5. Afterward, evolution of this trough begins to differ substantially amongst the models. The GFS depicts this trough evolving into cut-off low over the Upper Mississippi Valley/Upper Great Lakes region Day 6/Thursday, which then lingers in place through Day 8 and beyond. Meanwhile, the ECMWF remains slowly progressive with the trough into eastern North America through the period. Given these substantial differences, convective/severe potential cannot be reasonably assessed beyond Day 5. In the Day 4-5 time frame, a cold-frontal advance out of the western U.S. into the northern Plains -- and eventually the Great Lakes region -- is expected, in tandem with the progression of the aforementioned upper trough. However, with a surface high still firmly in place from the eastern U.S. westward into the central/southern Plains, Gulf moisture will remain suppressed, and thus the likelihood for only meager destabilization across the pre-frontal warm sector. Therefore, severe risk is expected to remain limited, thus not requiring a 15% areal outline associated with this system through Day 5. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Sat Aug 31 2024 Valid 021200Z - 031200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe-weather potential is forecast to remain quite limited, and isolated at best, across the U.S. on Monday. ...Discussion... As a long-wave upper trough continues to shift across eastern Canada and the eastern U.S. Monday, a cold front -- already off the New England and Mid-Atlantic Coasts early in the day -- is forecast to linger from the southeastern U.S. Atlantic Coast westward across the Gulf Coast region. This front will represent the southern/eastern bounds of a cool/dry continental airmass from Canada -- represented by large area of surface high pressure to encompass much of the central and eastern CONUS. Showers and thunderstorms are forecast across the Southeast, Gulf Coast States, and Southern Plains area, but with stronger flow aloft well to the north, severe-weather potential should remain minimal. In the West, an upper trough will shift east-northeastward across the northwestern states, impinging on a persistent upper ridge. Showers and scattered to isolated thunderstorms are expected across portions of the West ahead of this system, but with little in the way of severe potential evident due to meager instability forecast across the area. ..Goss.. 08/31/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Sat Aug 31 2024 Valid 021200Z - 031200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe-weather potential is forecast to remain quite limited, and isolated at best, across the U.S. on Monday. ...Discussion... As a long-wave upper trough continues to shift across eastern Canada and the eastern U.S. Monday, a cold front -- already off the New England and Mid-Atlantic Coasts early in the day -- is forecast to linger from the southeastern U.S. Atlantic Coast westward across the Gulf Coast region. This front will represent the southern/eastern bounds of a cool/dry continental airmass from Canada -- represented by large area of surface high pressure to encompass much of the central and eastern CONUS. Showers and thunderstorms are forecast across the Southeast, Gulf Coast States, and Southern Plains area, but with stronger flow aloft well to the north, severe-weather potential should remain minimal. In the West, an upper trough will shift east-northeastward across the northwestern states, impinging on a persistent upper ridge. Showers and scattered to isolated thunderstorms are expected across portions of the West ahead of this system, but with little in the way of severe potential evident due to meager instability forecast across the area. ..Goss.. 08/31/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Sat Aug 31 2024 Valid 021200Z - 031200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe-weather potential is forecast to remain quite limited, and isolated at best, across the U.S. on Monday. ...Discussion... As a long-wave upper trough continues to shift across eastern Canada and the eastern U.S. Monday, a cold front -- already off the New England and Mid-Atlantic Coasts early in the day -- is forecast to linger from the southeastern U.S. Atlantic Coast westward across the Gulf Coast region. This front will represent the southern/eastern bounds of a cool/dry continental airmass from Canada -- represented by large area of surface high pressure to encompass much of the central and eastern CONUS. Showers and thunderstorms are forecast across the Southeast, Gulf Coast States, and Southern Plains area, but with stronger flow aloft well to the north, severe-weather potential should remain minimal. In the West, an upper trough will shift east-northeastward across the northwestern states, impinging on a persistent upper ridge. Showers and scattered to isolated thunderstorms are expected across portions of the West ahead of this system, but with little in the way of severe potential evident due to meager instability forecast across the area. ..Goss.. 08/31/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Sat Aug 31 2024 Valid 021200Z - 031200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe-weather potential is forecast to remain quite limited, and isolated at best, across the U.S. on Monday. ...Discussion... As a long-wave upper trough continues to shift across eastern Canada and the eastern U.S. Monday, a cold front -- already off the New England and Mid-Atlantic Coasts early in the day -- is forecast to linger from the southeastern U.S. Atlantic Coast westward across the Gulf Coast region. This front will represent the southern/eastern bounds of a cool/dry continental airmass from Canada -- represented by large area of surface high pressure to encompass much of the central and eastern CONUS. Showers and thunderstorms are forecast across the Southeast, Gulf Coast States, and Southern Plains area, but with stronger flow aloft well to the north, severe-weather potential should remain minimal. In the West, an upper trough will shift east-northeastward across the northwestern states, impinging on a persistent upper ridge. Showers and scattered to isolated thunderstorms are expected across portions of the West ahead of this system, but with little in the way of severe potential evident due to meager instability forecast across the area. ..Goss.. 08/31/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Sat Aug 31 2024 Valid 021200Z - 031200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe-weather potential is forecast to remain quite limited, and isolated at best, across the U.S. on Monday. ...Discussion... As a long-wave upper trough continues to shift across eastern Canada and the eastern U.S. Monday, a cold front -- already off the New England and Mid-Atlantic Coasts early in the day -- is forecast to linger from the southeastern U.S. Atlantic Coast westward across the Gulf Coast region. This front will represent the southern/eastern bounds of a cool/dry continental airmass from Canada -- represented by large area of surface high pressure to encompass much of the central and eastern CONUS. Showers and thunderstorms are forecast across the Southeast, Gulf Coast States, and Southern Plains area, but with stronger flow aloft well to the north, severe-weather potential should remain minimal. In the West, an upper trough will shift east-northeastward across the northwestern states, impinging on a persistent upper ridge. Showers and scattered to isolated thunderstorms are expected across portions of the West ahead of this system, but with little in the way of severe potential evident due to meager instability forecast across the area. ..Goss.. 08/31/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0121 AM CDT Sat Aug 31 2024 Valid 011200Z - 021200Z ...Synopsis... Dry thunderstorms will remain the primary fire weather concern on Sunday across parts of the Great Basin and Pacific Northwest. An upper-level low is evident in early-morning water-vapor imagery off the northern CA coast. This feature is expected to begin moving onshore Sunday afternoon into the overnight hours. Broadscale ascent ahead of this feature will overspread northern CA/southern OR and the northern Great Basin, resulting in slightly stronger surface winds compared to previous days (though generally at or below 15 mph) and isolated thunderstorm chances. Forecast soundings from across the region suggest buoyancy will be adequate for convection on the northern fringe of a modest monsoonal moisture plume, but mixed-layer LCLs between 3 to 3.5 km (indicative of a deep, dry boundary-layer) will promote little rain accumulation. As such, dry lightning appears likely and will pose a fire weather threat given regional ERC values between the 80th to 90th percentiles. Stronger forcing for ascent may result in higher thunderstorm coverage across the Great Basin compared to previous days, and recent CAM solutions hint that central to northeast NV may see the greatest potential for dry lightning strikes. ..Moore.. 08/31/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0121 AM CDT Sat Aug 31 2024 Valid 011200Z - 021200Z ...Synopsis... Dry thunderstorms will remain the primary fire weather concern on Sunday across parts of the Great Basin and Pacific Northwest. An upper-level low is evident in early-morning water-vapor imagery off the northern CA coast. This feature is expected to begin moving onshore Sunday afternoon into the overnight hours. Broadscale ascent ahead of this feature will overspread northern CA/southern OR and the northern Great Basin, resulting in slightly stronger surface winds compared to previous days (though generally at or below 15 mph) and isolated thunderstorm chances. Forecast soundings from across the region suggest buoyancy will be adequate for convection on the northern fringe of a modest monsoonal moisture plume, but mixed-layer LCLs between 3 to 3.5 km (indicative of a deep, dry boundary-layer) will promote little rain accumulation. As such, dry lightning appears likely and will pose a fire weather threat given regional ERC values between the 80th to 90th percentiles. Stronger forcing for ascent may result in higher thunderstorm coverage across the Great Basin compared to previous days, and recent CAM solutions hint that central to northeast NV may see the greatest potential for dry lightning strikes. ..Moore.. 08/31/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0121 AM CDT Sat Aug 31 2024 Valid 011200Z - 021200Z ...Synopsis... Dry thunderstorms will remain the primary fire weather concern on Sunday across parts of the Great Basin and Pacific Northwest. An upper-level low is evident in early-morning water-vapor imagery off the northern CA coast. This feature is expected to begin moving onshore Sunday afternoon into the overnight hours. Broadscale ascent ahead of this feature will overspread northern CA/southern OR and the northern Great Basin, resulting in slightly stronger surface winds compared to previous days (though generally at or below 15 mph) and isolated thunderstorm chances. Forecast soundings from across the region suggest buoyancy will be adequate for convection on the northern fringe of a modest monsoonal moisture plume, but mixed-layer LCLs between 3 to 3.5 km (indicative of a deep, dry boundary-layer) will promote little rain accumulation. As such, dry lightning appears likely and will pose a fire weather threat given regional ERC values between the 80th to 90th percentiles. Stronger forcing for ascent may result in higher thunderstorm coverage across the Great Basin compared to previous days, and recent CAM solutions hint that central to northeast NV may see the greatest potential for dry lightning strikes. ..Moore.. 08/31/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more