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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1112 AM CST Wed Dec 27 2023 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered thunderstorms are forecast across the Florida Keys and far southern Florida early on Thursday. Severe storms appear unlikely. ...Synopsis and Discussion... A large, deep-layer cyclone will move east across the lower MS to OH Valleys, with a broad area of strong southwesterlies aloft across the Southeast. While high pressure will maintain stable conditions over much of the CONUS, an unstable warm sector will exist ahead of the cold front as it moves from the far southeast Gulf of Mexico toward the Bahamas. Ahead of an embedded shortwave trough within the southwest flow regime, a surface low is forecast to move across the FL Straits, south of a cold front which will continue to push south. It appears unlikely that the low will be strong enough to counteract the undercutting cool/stable air mass, but the boundary could stall briefly just offshore until the low passes. The most likely result is for elevated instability to be present atop the cooler air mass, supporting scattered thunderstorms with several hundred J/kg MUCAPE. Lift will be enhanced by the right-entrance region of the upper jet as well as warm advection around 850 mb. Wind profiles will favor supercells over the Straits, but the severe risk is expected to be mitigated over land due to the post-frontal air mass/decoupled boundary layer, rendering low-level shear ineffective. ..Jewell.. 12/27/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1112 AM CST Wed Dec 27 2023 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered thunderstorms are forecast across the Florida Keys and far southern Florida early on Thursday. Severe storms appear unlikely. ...Synopsis and Discussion... A large, deep-layer cyclone will move east across the lower MS to OH Valleys, with a broad area of strong southwesterlies aloft across the Southeast. While high pressure will maintain stable conditions over much of the CONUS, an unstable warm sector will exist ahead of the cold front as it moves from the far southeast Gulf of Mexico toward the Bahamas. Ahead of an embedded shortwave trough within the southwest flow regime, a surface low is forecast to move across the FL Straits, south of a cold front which will continue to push south. It appears unlikely that the low will be strong enough to counteract the undercutting cool/stable air mass, but the boundary could stall briefly just offshore until the low passes. The most likely result is for elevated instability to be present atop the cooler air mass, supporting scattered thunderstorms with several hundred J/kg MUCAPE. Lift will be enhanced by the right-entrance region of the upper jet as well as warm advection around 850 mb. Wind profiles will favor supercells over the Straits, but the severe risk is expected to be mitigated over land due to the post-frontal air mass/decoupled boundary layer, rendering low-level shear ineffective. ..Jewell.. 12/27/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1112 AM CST Wed Dec 27 2023 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered thunderstorms are forecast across the Florida Keys and far southern Florida early on Thursday. Severe storms appear unlikely. ...Synopsis and Discussion... A large, deep-layer cyclone will move east across the lower MS to OH Valleys, with a broad area of strong southwesterlies aloft across the Southeast. While high pressure will maintain stable conditions over much of the CONUS, an unstable warm sector will exist ahead of the cold front as it moves from the far southeast Gulf of Mexico toward the Bahamas. Ahead of an embedded shortwave trough within the southwest flow regime, a surface low is forecast to move across the FL Straits, south of a cold front which will continue to push south. It appears unlikely that the low will be strong enough to counteract the undercutting cool/stable air mass, but the boundary could stall briefly just offshore until the low passes. The most likely result is for elevated instability to be present atop the cooler air mass, supporting scattered thunderstorms with several hundred J/kg MUCAPE. Lift will be enhanced by the right-entrance region of the upper jet as well as warm advection around 850 mb. Wind profiles will favor supercells over the Straits, but the severe risk is expected to be mitigated over land due to the post-frontal air mass/decoupled boundary layer, rendering low-level shear ineffective. ..Jewell.. 12/27/2023 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1038 AM CST Wed Dec 27 2023 Valid 271700Z - 281200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/27/2023 .PREV DISCUSSION... /ISSUED 1241 AM CST Wed Dec 27 2023/ ...Synopsis... A large upper cyclone, centered over the central CONUS will slowly drift east during the period today. East of the upper low, warm/moist conditions have spread up the East Coast. Meanwhile, high pressure has brought cool conditions to the Intermountain West. Cool and/or moist conditions across most of the CONUS, combined with moist fuels will preclude the fire-weather threat today. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1038 AM CST Wed Dec 27 2023 Valid 271700Z - 281200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/27/2023 .PREV DISCUSSION... /ISSUED 1241 AM CST Wed Dec 27 2023/ ...Synopsis... A large upper cyclone, centered over the central CONUS will slowly drift east during the period today. East of the upper low, warm/moist conditions have spread up the East Coast. Meanwhile, high pressure has brought cool conditions to the Intermountain West. Cool and/or moist conditions across most of the CONUS, combined with moist fuels will preclude the fire-weather threat today. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1038 AM CST Wed Dec 27 2023 Valid 271700Z - 281200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/27/2023 .PREV DISCUSSION... /ISSUED 1241 AM CST Wed Dec 27 2023/ ...Synopsis... A large upper cyclone, centered over the central CONUS will slowly drift east during the period today. East of the upper low, warm/moist conditions have spread up the East Coast. Meanwhile, high pressure has brought cool conditions to the Intermountain West. Cool and/or moist conditions across most of the CONUS, combined with moist fuels will preclude the fire-weather threat today. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1038 AM CST Wed Dec 27 2023 Valid 271700Z - 281200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/27/2023 .PREV DISCUSSION... /ISSUED 1241 AM CST Wed Dec 27 2023/ ...Synopsis... A large upper cyclone, centered over the central CONUS will slowly drift east during the period today. East of the upper low, warm/moist conditions have spread up the East Coast. Meanwhile, high pressure has brought cool conditions to the Intermountain West. Cool and/or moist conditions across most of the CONUS, combined with moist fuels will preclude the fire-weather threat today. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1038 AM CST Wed Dec 27 2023 Valid 271700Z - 281200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/27/2023 .PREV DISCUSSION... /ISSUED 1241 AM CST Wed Dec 27 2023/ ...Synopsis... A large upper cyclone, centered over the central CONUS will slowly drift east during the period today. East of the upper low, warm/moist conditions have spread up the East Coast. Meanwhile, high pressure has brought cool conditions to the Intermountain West. Cool and/or moist conditions across most of the CONUS, combined with moist fuels will preclude the fire-weather threat today. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1038 AM CST Wed Dec 27 2023 Valid 271700Z - 281200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/27/2023 .PREV DISCUSSION... /ISSUED 1241 AM CST Wed Dec 27 2023/ ...Synopsis... A large upper cyclone, centered over the central CONUS will slowly drift east during the period today. East of the upper low, warm/moist conditions have spread up the East Coast. Meanwhile, high pressure has brought cool conditions to the Intermountain West. Cool and/or moist conditions across most of the CONUS, combined with moist fuels will preclude the fire-weather threat today. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1021 AM CST Wed Dec 27 2023 Valid 271630Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast across the contiguous United States through tonight. ...Mid Atlantic Region... A large upper low remains dominant over the central/eastern CONUS, with a deep warm-conveyor regime over the Mid-Atlantic region. Scattered showers and isolated thunderstorms will be possible this afternoon from eastern NC northward across the Chesapeake Bay area into PA/NJ. A cool and marginally unstable boundary-layer will preclude a risk of severe storms. ...FL Keys... A southern-stream shortwave trough over northern Mexico will track across the Gulf of Mexico and begin affecting the FL Keys after midnight. This may result in isolated thunderstorms over the lower Keys or nearby shelf waters. ...West Coast... A few lightning flashes are possible this afternoon and evening over coastal WA/OR and parts of northern/central CA as a cold front moves ashore. ..Hart/Thornton.. 12/27/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1021 AM CST Wed Dec 27 2023 Valid 271630Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast across the contiguous United States through tonight. ...Mid Atlantic Region... A large upper low remains dominant over the central/eastern CONUS, with a deep warm-conveyor regime over the Mid-Atlantic region. Scattered showers and isolated thunderstorms will be possible this afternoon from eastern NC northward across the Chesapeake Bay area into PA/NJ. A cool and marginally unstable boundary-layer will preclude a risk of severe storms. ...FL Keys... A southern-stream shortwave trough over northern Mexico will track across the Gulf of Mexico and begin affecting the FL Keys after midnight. This may result in isolated thunderstorms over the lower Keys or nearby shelf waters. ...West Coast... A few lightning flashes are possible this afternoon and evening over coastal WA/OR and parts of northern/central CA as a cold front moves ashore. ..Hart/Thornton.. 12/27/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1021 AM CST Wed Dec 27 2023 Valid 271630Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast across the contiguous United States through tonight. ...Mid Atlantic Region... A large upper low remains dominant over the central/eastern CONUS, with a deep warm-conveyor regime over the Mid-Atlantic region. Scattered showers and isolated thunderstorms will be possible this afternoon from eastern NC northward across the Chesapeake Bay area into PA/NJ. A cool and marginally unstable boundary-layer will preclude a risk of severe storms. ...FL Keys... A southern-stream shortwave trough over northern Mexico will track across the Gulf of Mexico and begin affecting the FL Keys after midnight. This may result in isolated thunderstorms over the lower Keys or nearby shelf waters. ...West Coast... A few lightning flashes are possible this afternoon and evening over coastal WA/OR and parts of northern/central CA as a cold front moves ashore. ..Hart/Thornton.. 12/27/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1021 AM CST Wed Dec 27 2023 Valid 271630Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast across the contiguous United States through tonight. ...Mid Atlantic Region... A large upper low remains dominant over the central/eastern CONUS, with a deep warm-conveyor regime over the Mid-Atlantic region. Scattered showers and isolated thunderstorms will be possible this afternoon from eastern NC northward across the Chesapeake Bay area into PA/NJ. A cool and marginally unstable boundary-layer will preclude a risk of severe storms. ...FL Keys... A southern-stream shortwave trough over northern Mexico will track across the Gulf of Mexico and begin affecting the FL Keys after midnight. This may result in isolated thunderstorms over the lower Keys or nearby shelf waters. ...West Coast... A few lightning flashes are possible this afternoon and evening over coastal WA/OR and parts of northern/central CA as a cold front moves ashore. ..Hart/Thornton.. 12/27/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1021 AM CST Wed Dec 27 2023 Valid 271630Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast across the contiguous United States through tonight. ...Mid Atlantic Region... A large upper low remains dominant over the central/eastern CONUS, with a deep warm-conveyor regime over the Mid-Atlantic region. Scattered showers and isolated thunderstorms will be possible this afternoon from eastern NC northward across the Chesapeake Bay area into PA/NJ. A cool and marginally unstable boundary-layer will preclude a risk of severe storms. ...FL Keys... A southern-stream shortwave trough over northern Mexico will track across the Gulf of Mexico and begin affecting the FL Keys after midnight. This may result in isolated thunderstorms over the lower Keys or nearby shelf waters. ...West Coast... A few lightning flashes are possible this afternoon and evening over coastal WA/OR and parts of northern/central CA as a cold front moves ashore. ..Hart/Thornton.. 12/27/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1021 AM CST Wed Dec 27 2023 Valid 271630Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast across the contiguous United States through tonight. ...Mid Atlantic Region... A large upper low remains dominant over the central/eastern CONUS, with a deep warm-conveyor regime over the Mid-Atlantic region. Scattered showers and isolated thunderstorms will be possible this afternoon from eastern NC northward across the Chesapeake Bay area into PA/NJ. A cool and marginally unstable boundary-layer will preclude a risk of severe storms. ...FL Keys... A southern-stream shortwave trough over northern Mexico will track across the Gulf of Mexico and begin affecting the FL Keys after midnight. This may result in isolated thunderstorms over the lower Keys or nearby shelf waters. ...West Coast... A few lightning flashes are possible this afternoon and evening over coastal WA/OR and parts of northern/central CA as a cold front moves ashore. ..Hart/Thornton.. 12/27/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0644 AM CST Wed Dec 27 2023 Valid 271300Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast across the contiguous United States through tonight. ...Synopsis/Discussion... In mid/upper levels, the dominant feature over the central/eastern CONUS remains a large synoptic-scale cyclone, initially centered over northwestern MO. Associated cyclonic flow extends from the Four Corners region to the central/southern Appalachians, and from the Upper Great Lakes to northern MX. Its 500-mb low is expected to pivot southward then eastward over southern IL by the end of the period. A broad warm conveyor lingers well east of the low, near the central Atlantic Coast and northward over the central Appalachians region. Weak, elevated buoyancy will decrease northward, with 12Z soundings showing MUCAPE around 600 J/kg at MHX, but less than 300 J/kg at RNK. This may support isolated, episodic thunder in a band of embedded convection moving eastward to northeastward over the area today into this evening. The surface cold front is offshore from the southern Atlantic Coast, though a frontal-wave low -- analyzed at 11Z just offshore from CHS -- should move northeastward near the NC coastline through this evening. However, favorable warm-sector buoyancy/shear for severe is expected to stay over the Atlantic. A temporarily stalled segment of the low-level frontal zone may undergo wave cyclogenesis over the southeastern Gulf this evening and tonight, as a weak southern-stream perturbation approaches from MX. Sufficient lift, elevated instability and moisture should exist over Gulf waters to support thunderstorms over the central/east-central Gulf today and the east-central/southeastern Gulf tonight. Some of this activity may reach portions of the FL Keys before 12Z tomorrow. Farther west, moisture-channel imagery showed a synoptic-scale cyclone over the northeast Pacific, centered near 43N137W. This feature is expected to move northeastward and weaken today, while remaining offshore. However, a basal shortwave trough should pivot northeastward across the coastal Pacific Northwest. Related DCVA/cooling aloft may provide sufficient destabilization, atop weak low/middle-level moisture, to support thunder potential from portions of northern CA up the coast of OR/WA. ..Edwards/Dean.. 12/27/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0644 AM CST Wed Dec 27 2023 Valid 271300Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast across the contiguous United States through tonight. ...Synopsis/Discussion... In mid/upper levels, the dominant feature over the central/eastern CONUS remains a large synoptic-scale cyclone, initially centered over northwestern MO. Associated cyclonic flow extends from the Four Corners region to the central/southern Appalachians, and from the Upper Great Lakes to northern MX. Its 500-mb low is expected to pivot southward then eastward over southern IL by the end of the period. A broad warm conveyor lingers well east of the low, near the central Atlantic Coast and northward over the central Appalachians region. Weak, elevated buoyancy will decrease northward, with 12Z soundings showing MUCAPE around 600 J/kg at MHX, but less than 300 J/kg at RNK. This may support isolated, episodic thunder in a band of embedded convection moving eastward to northeastward over the area today into this evening. The surface cold front is offshore from the southern Atlantic Coast, though a frontal-wave low -- analyzed at 11Z just offshore from CHS -- should move northeastward near the NC coastline through this evening. However, favorable warm-sector buoyancy/shear for severe is expected to stay over the Atlantic. A temporarily stalled segment of the low-level frontal zone may undergo wave cyclogenesis over the southeastern Gulf this evening and tonight, as a weak southern-stream perturbation approaches from MX. Sufficient lift, elevated instability and moisture should exist over Gulf waters to support thunderstorms over the central/east-central Gulf today and the east-central/southeastern Gulf tonight. Some of this activity may reach portions of the FL Keys before 12Z tomorrow. Farther west, moisture-channel imagery showed a synoptic-scale cyclone over the northeast Pacific, centered near 43N137W. This feature is expected to move northeastward and weaken today, while remaining offshore. However, a basal shortwave trough should pivot northeastward across the coastal Pacific Northwest. Related DCVA/cooling aloft may provide sufficient destabilization, atop weak low/middle-level moisture, to support thunder potential from portions of northern CA up the coast of OR/WA. ..Edwards/Dean.. 12/27/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0644 AM CST Wed Dec 27 2023 Valid 271300Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast across the contiguous United States through tonight. ...Synopsis/Discussion... In mid/upper levels, the dominant feature over the central/eastern CONUS remains a large synoptic-scale cyclone, initially centered over northwestern MO. Associated cyclonic flow extends from the Four Corners region to the central/southern Appalachians, and from the Upper Great Lakes to northern MX. Its 500-mb low is expected to pivot southward then eastward over southern IL by the end of the period. A broad warm conveyor lingers well east of the low, near the central Atlantic Coast and northward over the central Appalachians region. Weak, elevated buoyancy will decrease northward, with 12Z soundings showing MUCAPE around 600 J/kg at MHX, but less than 300 J/kg at RNK. This may support isolated, episodic thunder in a band of embedded convection moving eastward to northeastward over the area today into this evening. The surface cold front is offshore from the southern Atlantic Coast, though a frontal-wave low -- analyzed at 11Z just offshore from CHS -- should move northeastward near the NC coastline through this evening. However, favorable warm-sector buoyancy/shear for severe is expected to stay over the Atlantic. A temporarily stalled segment of the low-level frontal zone may undergo wave cyclogenesis over the southeastern Gulf this evening and tonight, as a weak southern-stream perturbation approaches from MX. Sufficient lift, elevated instability and moisture should exist over Gulf waters to support thunderstorms over the central/east-central Gulf today and the east-central/southeastern Gulf tonight. Some of this activity may reach portions of the FL Keys before 12Z tomorrow. Farther west, moisture-channel imagery showed a synoptic-scale cyclone over the northeast Pacific, centered near 43N137W. This feature is expected to move northeastward and weaken today, while remaining offshore. However, a basal shortwave trough should pivot northeastward across the coastal Pacific Northwest. Related DCVA/cooling aloft may provide sufficient destabilization, atop weak low/middle-level moisture, to support thunder potential from portions of northern CA up the coast of OR/WA. ..Edwards/Dean.. 12/27/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0644 AM CST Wed Dec 27 2023 Valid 271300Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast across the contiguous United States through tonight. ...Synopsis/Discussion... In mid/upper levels, the dominant feature over the central/eastern CONUS remains a large synoptic-scale cyclone, initially centered over northwestern MO. Associated cyclonic flow extends from the Four Corners region to the central/southern Appalachians, and from the Upper Great Lakes to northern MX. Its 500-mb low is expected to pivot southward then eastward over southern IL by the end of the period. A broad warm conveyor lingers well east of the low, near the central Atlantic Coast and northward over the central Appalachians region. Weak, elevated buoyancy will decrease northward, with 12Z soundings showing MUCAPE around 600 J/kg at MHX, but less than 300 J/kg at RNK. This may support isolated, episodic thunder in a band of embedded convection moving eastward to northeastward over the area today into this evening. The surface cold front is offshore from the southern Atlantic Coast, though a frontal-wave low -- analyzed at 11Z just offshore from CHS -- should move northeastward near the NC coastline through this evening. However, favorable warm-sector buoyancy/shear for severe is expected to stay over the Atlantic. A temporarily stalled segment of the low-level frontal zone may undergo wave cyclogenesis over the southeastern Gulf this evening and tonight, as a weak southern-stream perturbation approaches from MX. Sufficient lift, elevated instability and moisture should exist over Gulf waters to support thunderstorms over the central/east-central Gulf today and the east-central/southeastern Gulf tonight. Some of this activity may reach portions of the FL Keys before 12Z tomorrow. Farther west, moisture-channel imagery showed a synoptic-scale cyclone over the northeast Pacific, centered near 43N137W. This feature is expected to move northeastward and weaken today, while remaining offshore. However, a basal shortwave trough should pivot northeastward across the coastal Pacific Northwest. Related DCVA/cooling aloft may provide sufficient destabilization, atop weak low/middle-level moisture, to support thunder potential from portions of northern CA up the coast of OR/WA. ..Edwards/Dean.. 12/27/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0644 AM CST Wed Dec 27 2023 Valid 271300Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast across the contiguous United States through tonight. ...Synopsis/Discussion... In mid/upper levels, the dominant feature over the central/eastern CONUS remains a large synoptic-scale cyclone, initially centered over northwestern MO. Associated cyclonic flow extends from the Four Corners region to the central/southern Appalachians, and from the Upper Great Lakes to northern MX. Its 500-mb low is expected to pivot southward then eastward over southern IL by the end of the period. A broad warm conveyor lingers well east of the low, near the central Atlantic Coast and northward over the central Appalachians region. Weak, elevated buoyancy will decrease northward, with 12Z soundings showing MUCAPE around 600 J/kg at MHX, but less than 300 J/kg at RNK. This may support isolated, episodic thunder in a band of embedded convection moving eastward to northeastward over the area today into this evening. The surface cold front is offshore from the southern Atlantic Coast, though a frontal-wave low -- analyzed at 11Z just offshore from CHS -- should move northeastward near the NC coastline through this evening. However, favorable warm-sector buoyancy/shear for severe is expected to stay over the Atlantic. A temporarily stalled segment of the low-level frontal zone may undergo wave cyclogenesis over the southeastern Gulf this evening and tonight, as a weak southern-stream perturbation approaches from MX. Sufficient lift, elevated instability and moisture should exist over Gulf waters to support thunderstorms over the central/east-central Gulf today and the east-central/southeastern Gulf tonight. Some of this activity may reach portions of the FL Keys before 12Z tomorrow. Farther west, moisture-channel imagery showed a synoptic-scale cyclone over the northeast Pacific, centered near 43N137W. This feature is expected to move northeastward and weaken today, while remaining offshore. However, a basal shortwave trough should pivot northeastward across the coastal Pacific Northwest. Related DCVA/cooling aloft may provide sufficient destabilization, atop weak low/middle-level moisture, to support thunder potential from portions of northern CA up the coast of OR/WA. ..Edwards/Dean.. 12/27/2023 Read more