Severe Storms

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0403 PM CDT Sat Aug 17 2024 Valid 191200Z - 251200Z Elevated fire weather conditions are likely across the Great Basin through the extended, with critical fire weather conditions possible. The driving factors for this regime will be a blocking pattern, where an upper-level ridge over the central US will support persistent hot/dry conditions across the Great Basin across the southern Rockies, into the Southern Plains. Given poor fuel moisture recovery beneath this ridge, especially across the Great Basin, any increase in wind speed (including terrain driven circulations) will result in at least elevated fire weather conditions. Late in the forecast period (Day 7/8), large-scale guidance suggests an increase in mid-level flow may result in surface wind speeds sufficient for critical fire weather conditions. However, uncertainty in the timing/magnitude of the large-scale pattern evolution precludes the ability to denote areas of concerns late next week. ..Marsh.. 08/17/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0632 Status Updates
STATUS FOR WATCH 0632 HAS NOT BEEN ISSUED YET Read more

WW 0630 Status Updates
STATUS REPORT ON WW 630 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..BENTLEY..08/17/24 ATTN...WFO...SLC... STATUS REPORT FOR WS 630 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS UTC001-007-013-015-017-021-023-025-027-031-035-039-041-043-045- 049-051-053-055-172140- UT . UTAH COUNTIES INCLUDED ARE BEAVER CARBON DUCHESNE EMERY GARFIELD IRON JUAB KANE MILLARD PIUTE SALT LAKE SANPETE SEVIER SUMMIT TOOELE UTAH WASATCH WASHINGTON WAYNE WYC041-172140- WY . WYOMING COUNTIES INCLUDED ARE UINTA THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES Read more

WW 0631 Status Updates
STATUS FOR WATCH 0631 HAS NOT BEEN ISSUED YET Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 17 2024 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CASCADES AND COLUMBIA BASIN...PARTS OF UTAH...AND IN THE OHIO/TENNESSEE VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible through tonight in vicinity of the Ohio Valley, Utah and the Cascades of Oregon and Washington. Wind and isolated hail are the primary threats. ...20z Update... The forecast remains largely on track with on minor changes. Strong to severe storms ongoing over the OH Valley and eastern US will remain capable of isolated damaging gusts through this evening. Scattered severe storms are also expected to develop over the Cascades and Columbia Basin later this afternoon and into the overnight hours with a risk for danging winds and hail. ...Tennessee Valley and southern Appalachians.... Multiple bands and clusters of strong to occasional severe storms are ongoing this afternoon ahead of the broad upper trough and slow moving cold front. Recent VAD observations from HTX and MRX show a belt of stronger mid-level flow has extend over parts of the eastern TN Valley and Southern Appalachians supporting greater deep-layer shear of 25-30 kt. Colocated with a hot and seasonably moist/unstable air mass, a cluster of more organized/robust convection being observed over part of northern AL and southern TN may continue east/southeast into parts of northern GA and the western Carolinas this afternoon/evening. A mix of persistent multi-cell clusters and transient supercell structures would support a risk for damaging winds and isolated hail. Have upgraded to level 2 categorical Slight to better account for the risk of damaging winds with this cluster of stronger storms. ...Utah... Ahead of a convective enhanced shortwave trough, scattered strong to severe thunderstorms should continue this afternoon and into the evening hours with a risk for damaging winds and occasional hail. Confidence in the highest threat corridor remains across parts of central UT where greater diurnal heating has allowed for moderate destabilization. The exact eastern extent of organized convective potential is somewhat nebulous given the limited buoyancy and expected degree of storm coverage. However, at least some risk for damaging gusts will be possible with high-based showers and storms over eastern UT. Have modified the eastern edge of the level-2 Slight Risk to better reflect the potential for organized storms with wind gust and hail potential later this afternoon. Otherwise, see the prior discussion for additional information. ..Lyons.. 08/17/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Aug 17 2024/ ...CA/OR/WA... Morning water vapor loop shows a strong and fast-moving shortwave trough approaching the coast of northern CA. This feature will rotate inland, affecting the Cascades region this afternoon and evening. Steep mid level lapse rates and pockets of MLCAPE of 500-1000 J/kg will aid in the development of scattered thunderstorms by early afternoon over the mountains and coastal ranges of northern CA, building quickly northward into southern/central OR. Winds aloft will be strenghtening during this period, allowing a few supercell storm structures to likely develop. These storms may pose a threat of large hail and locally damaging wind gusts through the afternoon as they track northward into WA. Other high-based storms capable of gusty/damaging winds may affect parts of the Columbia Basin of northern OR/central WA as well. ...UT... A compact shortwave trough over central NV will continue to rotate around the Four-Corners upper ridge into UT today. Considerable coverage of afternoon thunderstorms will likely accompany this system. Winds aloft will be relatively strong, favoring faster-moving organized multicell or occasional supercell structures capable of damaging winds and hail. One forecast uncertainty is the extent of morning cloudiness and its impact on afternoon destabilization. Regardless, at least isolated severe storms are expected, with some threat spreading into southwest WY by evening. ...Eastern US... A broad upper trough will affect much of the eastern US today, with clusters of thunderstorms from NY/PA across the Appalachians into the Mid South. Any of these clusters may occasionally pose a risk of locally gusty/damaging wind gusts or hail. However, perhaps a more focused area of concern will extend from northern TN into southern OH. The axis of the mid level speed max (~40 knots) will spread across this area during the afternoon. CAM guidance has been consistent on suggesting a higher confidence in a few intense cells in this region. Read more