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SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0225 AM CST Tue Nov 28 2023 Valid 301200Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF SOUTHEAST TEXAS AND INTO FAR WESTERN LOUISIANA... ...SUMMARY... Scattered storms, some severe, will be possible during the day on Thursday, mainly over southeast Texas. ...Synopsis and Discussion... A shortwave trough will move quickly east across NM and into northwest TX on Thursday, then eject northeastward across OK and into MO overnight. Modest height falls are forecast across much of the southern Plains during the day, but rapid warming aloft will occur over southern parts of TX and LA by mid afternoon as the upper wave ejects. A relatively early risk of severe storms, including a few tornadoes, appears possible mainly from late morning through mid afternoon across southeast TX, while temperatures aloft remain cool and midlevel lapse rates are maximized. A plume of upper 60s F to near 70 F dewpoints will spread inland, with MLCAPE through midday of around 1500 J/kg. Given the warm advection regime and antecedent cooler air mass with high pressure to the east, substantial southerly flow including 50+ kt at 850 mb is forecast, which will enhance shear. Effective SRH looks to be maximized from midday to early afternoon, with values over 300 m2/s2. There appears to be at least a few hours of overlap between the more favorable instability and stronger shear, and during this time, supercells including a couple tornadoes could occur. Early day storms could be substantial and affect air mass quality. However, this event will be driven mainly by moisture advection and isolated severe cells within any larger scale convective area will still have severe potential, including brief tornadoes. ..Jewell.. 11/28/2023 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0140 AM CST Tue Nov 28 2023 Valid 291200Z - 301200Z ...NO CRITICAL AREAS... ...Synopsis... A southern-stream midlevel trough will track eastward across the Southwest, preceded by strengthening southwesterly flow and increasing mid/high-level clouds crossing the southern Rockies. This will promote breezy/gusty southerly return flow over portions of the southern and central Plains. However, the increasing cloud coverage and low-level moisture advection (albeit weak) should limit RH reductions where the breezy winds are expected. Elsewhere across the CONUS, cool and/or moist conditions should limit fire-weather concerns. ..Weinman.. 11/28/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0140 AM CST Tue Nov 28 2023 Valid 291200Z - 301200Z ...NO CRITICAL AREAS... ...Synopsis... A southern-stream midlevel trough will track eastward across the Southwest, preceded by strengthening southwesterly flow and increasing mid/high-level clouds crossing the southern Rockies. This will promote breezy/gusty southerly return flow over portions of the southern and central Plains. However, the increasing cloud coverage and low-level moisture advection (albeit weak) should limit RH reductions where the breezy winds are expected. Elsewhere across the CONUS, cool and/or moist conditions should limit fire-weather concerns. ..Weinman.. 11/28/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0140 AM CST Tue Nov 28 2023 Valid 291200Z - 301200Z ...NO CRITICAL AREAS... ...Synopsis... A southern-stream midlevel trough will track eastward across the Southwest, preceded by strengthening southwesterly flow and increasing mid/high-level clouds crossing the southern Rockies. This will promote breezy/gusty southerly return flow over portions of the southern and central Plains. However, the increasing cloud coverage and low-level moisture advection (albeit weak) should limit RH reductions where the breezy winds are expected. Elsewhere across the CONUS, cool and/or moist conditions should limit fire-weather concerns. ..Weinman.. 11/28/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0140 AM CST Tue Nov 28 2023 Valid 291200Z - 301200Z ...NO CRITICAL AREAS... ...Synopsis... A southern-stream midlevel trough will track eastward across the Southwest, preceded by strengthening southwesterly flow and increasing mid/high-level clouds crossing the southern Rockies. This will promote breezy/gusty southerly return flow over portions of the southern and central Plains. However, the increasing cloud coverage and low-level moisture advection (albeit weak) should limit RH reductions where the breezy winds are expected. Elsewhere across the CONUS, cool and/or moist conditions should limit fire-weather concerns. ..Weinman.. 11/28/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0140 AM CST Tue Nov 28 2023 Valid 291200Z - 301200Z ...NO CRITICAL AREAS... ...Synopsis... A southern-stream midlevel trough will track eastward across the Southwest, preceded by strengthening southwesterly flow and increasing mid/high-level clouds crossing the southern Rockies. This will promote breezy/gusty southerly return flow over portions of the southern and central Plains. However, the increasing cloud coverage and low-level moisture advection (albeit weak) should limit RH reductions where the breezy winds are expected. Elsewhere across the CONUS, cool and/or moist conditions should limit fire-weather concerns. ..Weinman.. 11/28/2023 ...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 0140 AM CST Tue Nov 28 2023 Valid 281200Z - 291200Z ...NO CRITICAL AREAS... ...Synopsis... On the backside of a departing large-scale trough over the Northeast, strong deep-layer west-northwesterly flow will overspread the Southeast. At the same time, surface high pressure will shift east-southeastward from the Great Plains into the central Gulf Coast. Along the eastern periphery of the surface high, an enhanced pressure gradient will support 10-15 mph northwesterly surface winds (with higher gusts), while shallow boundary-layer mixing into dry air aloft favors 25-35 percent minimum RH across portions of the Southeast and southern Appalachians. While locally elevated fire-weather conditions are possible for these areas, recent rainfall and generally cool surface temperatures should limit the overall threat. Farther west, strong northwesterly flow aloft will cross the northern Rockies, yielding dry/breezy downslope flow into the northern High Plains. A lack of appreciable precipitation over this area suggests that fuels are at least modestly receptive, and locally elevated fire-weather conditions are possible. Similar to the Southeast, cool surface temperatures should mitigate the threat. ..Weinman.. 11/28/2023 ...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 0140 AM CST Tue Nov 28 2023 Valid 281200Z - 291200Z ...NO CRITICAL AREAS... ...Synopsis... On the backside of a departing large-scale trough over the Northeast, strong deep-layer west-northwesterly flow will overspread the Southeast. At the same time, surface high pressure will shift east-southeastward from the Great Plains into the central Gulf Coast. Along the eastern periphery of the surface high, an enhanced pressure gradient will support 10-15 mph northwesterly surface winds (with higher gusts), while shallow boundary-layer mixing into dry air aloft favors 25-35 percent minimum RH across portions of the Southeast and southern Appalachians. While locally elevated fire-weather conditions are possible for these areas, recent rainfall and generally cool surface temperatures should limit the overall threat. Farther west, strong northwesterly flow aloft will cross the northern Rockies, yielding dry/breezy downslope flow into the northern High Plains. A lack of appreciable precipitation over this area suggests that fuels are at least modestly receptive, and locally elevated fire-weather conditions are possible. Similar to the Southeast, cool surface temperatures should mitigate the threat. ..Weinman.. 11/28/2023 ...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 0140 AM CST Tue Nov 28 2023 Valid 281200Z - 291200Z ...NO CRITICAL AREAS... ...Synopsis... On the backside of a departing large-scale trough over the Northeast, strong deep-layer west-northwesterly flow will overspread the Southeast. At the same time, surface high pressure will shift east-southeastward from the Great Plains into the central Gulf Coast. Along the eastern periphery of the surface high, an enhanced pressure gradient will support 10-15 mph northwesterly surface winds (with higher gusts), while shallow boundary-layer mixing into dry air aloft favors 25-35 percent minimum RH across portions of the Southeast and southern Appalachians. While locally elevated fire-weather conditions are possible for these areas, recent rainfall and generally cool surface temperatures should limit the overall threat. Farther west, strong northwesterly flow aloft will cross the northern Rockies, yielding dry/breezy downslope flow into the northern High Plains. A lack of appreciable precipitation over this area suggests that fuels are at least modestly receptive, and locally elevated fire-weather conditions are possible. Similar to the Southeast, cool surface temperatures should mitigate the threat. ..Weinman.. 11/28/2023 ...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 0140 AM CST Tue Nov 28 2023 Valid 281200Z - 291200Z ...NO CRITICAL AREAS... ...Synopsis... On the backside of a departing large-scale trough over the Northeast, strong deep-layer west-northwesterly flow will overspread the Southeast. At the same time, surface high pressure will shift east-southeastward from the Great Plains into the central Gulf Coast. Along the eastern periphery of the surface high, an enhanced pressure gradient will support 10-15 mph northwesterly surface winds (with higher gusts), while shallow boundary-layer mixing into dry air aloft favors 25-35 percent minimum RH across portions of the Southeast and southern Appalachians. While locally elevated fire-weather conditions are possible for these areas, recent rainfall and generally cool surface temperatures should limit the overall threat. Farther west, strong northwesterly flow aloft will cross the northern Rockies, yielding dry/breezy downslope flow into the northern High Plains. A lack of appreciable precipitation over this area suggests that fuels are at least modestly receptive, and locally elevated fire-weather conditions are possible. Similar to the Southeast, cool surface temperatures should mitigate the threat. ..Weinman.. 11/28/2023 ...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 0140 AM CST Tue Nov 28 2023 Valid 281200Z - 291200Z ...NO CRITICAL AREAS... ...Synopsis... On the backside of a departing large-scale trough over the Northeast, strong deep-layer west-northwesterly flow will overspread the Southeast. At the same time, surface high pressure will shift east-southeastward from the Great Plains into the central Gulf Coast. Along the eastern periphery of the surface high, an enhanced pressure gradient will support 10-15 mph northwesterly surface winds (with higher gusts), while shallow boundary-layer mixing into dry air aloft favors 25-35 percent minimum RH across portions of the Southeast and southern Appalachians. While locally elevated fire-weather conditions are possible for these areas, recent rainfall and generally cool surface temperatures should limit the overall threat. Farther west, strong northwesterly flow aloft will cross the northern Rockies, yielding dry/breezy downslope flow into the northern High Plains. A lack of appreciable precipitation over this area suggests that fuels are at least modestly receptive, and locally elevated fire-weather conditions are possible. Similar to the Southeast, cool surface temperatures should mitigate the threat. ..Weinman.. 11/28/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1222 AM CST Tue Nov 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered thunderstorms will develop late Wednesday into early Thursday over much of southern and eastern Texas. Severe weather appears unlikely. ...Synopsis and Discussion... A shortwave trough will move across CA and into western AZ by 00Z Thursday, and will proceed eastward overnight toward NM. Ahead of this feature, heights will fall gradually into the southern High Plains, with relatively neutral tendencies farther east beneath moderate southwest flow. In anticipation of this trough, low-level winds will increase out of the south, especially above the surface near 850 mb where positive theta-e advection will develop. This will result in elevated instability over the relatively cool surface layer over parts of central and eastern TX. Scattered elevated storms are expected, with little if any hail potential. Overnight, some models suggest surface-based instability along the middle TX Coast, where low-level shear will conditionally favor supercells. Forecast soundings depict moist adiabatic lapse rates in the boundary layer combined with subtle capping just below 700 mb, which may prevent much surface-based convection over land through 12Z Thursday. In addition, the potential for deeper convective confluence lines over the western Gulf is unclear given lack of deeper convergence aside from shoreline speed convergences. Given these factors, severe weather is currently not forecast. Elsewhere, showers associated with an upper trough over CA are expected to offer little lightning activity as the trough proceeds eastward away from the coast during the day, with minimal instability. ..Jewell.. 11/28/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1222 AM CST Tue Nov 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered thunderstorms will develop late Wednesday into early Thursday over much of southern and eastern Texas. Severe weather appears unlikely. ...Synopsis and Discussion... A shortwave trough will move across CA and into western AZ by 00Z Thursday, and will proceed eastward overnight toward NM. Ahead of this feature, heights will fall gradually into the southern High Plains, with relatively neutral tendencies farther east beneath moderate southwest flow. In anticipation of this trough, low-level winds will increase out of the south, especially above the surface near 850 mb where positive theta-e advection will develop. This will result in elevated instability over the relatively cool surface layer over parts of central and eastern TX. Scattered elevated storms are expected, with little if any hail potential. Overnight, some models suggest surface-based instability along the middle TX Coast, where low-level shear will conditionally favor supercells. Forecast soundings depict moist adiabatic lapse rates in the boundary layer combined with subtle capping just below 700 mb, which may prevent much surface-based convection over land through 12Z Thursday. In addition, the potential for deeper convective confluence lines over the western Gulf is unclear given lack of deeper convergence aside from shoreline speed convergences. Given these factors, severe weather is currently not forecast. Elsewhere, showers associated with an upper trough over CA are expected to offer little lightning activity as the trough proceeds eastward away from the coast during the day, with minimal instability. ..Jewell.. 11/28/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1222 AM CST Tue Nov 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered thunderstorms will develop late Wednesday into early Thursday over much of southern and eastern Texas. Severe weather appears unlikely. ...Synopsis and Discussion... A shortwave trough will move across CA and into western AZ by 00Z Thursday, and will proceed eastward overnight toward NM. Ahead of this feature, heights will fall gradually into the southern High Plains, with relatively neutral tendencies farther east beneath moderate southwest flow. In anticipation of this trough, low-level winds will increase out of the south, especially above the surface near 850 mb where positive theta-e advection will develop. This will result in elevated instability over the relatively cool surface layer over parts of central and eastern TX. Scattered elevated storms are expected, with little if any hail potential. Overnight, some models suggest surface-based instability along the middle TX Coast, where low-level shear will conditionally favor supercells. Forecast soundings depict moist adiabatic lapse rates in the boundary layer combined with subtle capping just below 700 mb, which may prevent much surface-based convection over land through 12Z Thursday. In addition, the potential for deeper convective confluence lines over the western Gulf is unclear given lack of deeper convergence aside from shoreline speed convergences. Given these factors, severe weather is currently not forecast. Elsewhere, showers associated with an upper trough over CA are expected to offer little lightning activity as the trough proceeds eastward away from the coast during the day, with minimal instability. ..Jewell.. 11/28/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1222 AM CST Tue Nov 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered thunderstorms will develop late Wednesday into early Thursday over much of southern and eastern Texas. Severe weather appears unlikely. ...Synopsis and Discussion... A shortwave trough will move across CA and into western AZ by 00Z Thursday, and will proceed eastward overnight toward NM. Ahead of this feature, heights will fall gradually into the southern High Plains, with relatively neutral tendencies farther east beneath moderate southwest flow. In anticipation of this trough, low-level winds will increase out of the south, especially above the surface near 850 mb where positive theta-e advection will develop. This will result in elevated instability over the relatively cool surface layer over parts of central and eastern TX. Scattered elevated storms are expected, with little if any hail potential. Overnight, some models suggest surface-based instability along the middle TX Coast, where low-level shear will conditionally favor supercells. Forecast soundings depict moist adiabatic lapse rates in the boundary layer combined with subtle capping just below 700 mb, which may prevent much surface-based convection over land through 12Z Thursday. In addition, the potential for deeper convective confluence lines over the western Gulf is unclear given lack of deeper convergence aside from shoreline speed convergences. Given these factors, severe weather is currently not forecast. Elsewhere, showers associated with an upper trough over CA are expected to offer little lightning activity as the trough proceeds eastward away from the coast during the day, with minimal instability. ..Jewell.. 11/28/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1222 AM CST Tue Nov 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered thunderstorms will develop late Wednesday into early Thursday over much of southern and eastern Texas. Severe weather appears unlikely. ...Synopsis and Discussion... A shortwave trough will move across CA and into western AZ by 00Z Thursday, and will proceed eastward overnight toward NM. Ahead of this feature, heights will fall gradually into the southern High Plains, with relatively neutral tendencies farther east beneath moderate southwest flow. In anticipation of this trough, low-level winds will increase out of the south, especially above the surface near 850 mb where positive theta-e advection will develop. This will result in elevated instability over the relatively cool surface layer over parts of central and eastern TX. Scattered elevated storms are expected, with little if any hail potential. Overnight, some models suggest surface-based instability along the middle TX Coast, where low-level shear will conditionally favor supercells. Forecast soundings depict moist adiabatic lapse rates in the boundary layer combined with subtle capping just below 700 mb, which may prevent much surface-based convection over land through 12Z Thursday. In addition, the potential for deeper convective confluence lines over the western Gulf is unclear given lack of deeper convergence aside from shoreline speed convergences. Given these factors, severe weather is currently not forecast. Elsewhere, showers associated with an upper trough over CA are expected to offer little lightning activity as the trough proceeds eastward away from the coast during the day, with minimal instability. ..Jewell.. 11/28/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1222 AM CST Tue Nov 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered thunderstorms will develop late Wednesday into early Thursday over much of southern and eastern Texas. Severe weather appears unlikely. ...Synopsis and Discussion... A shortwave trough will move across CA and into western AZ by 00Z Thursday, and will proceed eastward overnight toward NM. Ahead of this feature, heights will fall gradually into the southern High Plains, with relatively neutral tendencies farther east beneath moderate southwest flow. In anticipation of this trough, low-level winds will increase out of the south, especially above the surface near 850 mb where positive theta-e advection will develop. This will result in elevated instability over the relatively cool surface layer over parts of central and eastern TX. Scattered elevated storms are expected, with little if any hail potential. Overnight, some models suggest surface-based instability along the middle TX Coast, where low-level shear will conditionally favor supercells. Forecast soundings depict moist adiabatic lapse rates in the boundary layer combined with subtle capping just below 700 mb, which may prevent much surface-based convection over land through 12Z Thursday. In addition, the potential for deeper convective confluence lines over the western Gulf is unclear given lack of deeper convergence aside from shoreline speed convergences. Given these factors, severe weather is currently not forecast. Elsewhere, showers associated with an upper trough over CA are expected to offer little lightning activity as the trough proceeds eastward away from the coast during the day, with minimal instability. ..Jewell.. 11/28/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1106 PM CST Mon Nov 27 2023 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across much of the U.S., today through tonight. ...Synopsis... Split westerlies emanating from the mid-latitude Pacific will continue to converge into broad, deep troughing east of the Great Plains into the western Atlantic. Within this regime, models indicate that one significant short wave perturbation, crossing the lower Great Lakes/upper Ohio Valley at the outset of the period, will fairly rapidly pivot across the northern Atlantic Seaboard by early this evening. However, broadly cyclonic northwesterly mid-level flow appears likely to linger across and east of the Mississippi Valley. Cool to cold, dry and stable conditions will generally be maintained beneath this regime, while downslope warming contributes to moderating temperatures across much of the Great Plains. Upstream, within a branch of westerlies across the southern mid-latitude eastern Pacific into the Southwest, mid-level troughing is forecast to dig across the California coast, with an embedded weakening low and associated occluding surface cyclone approaching the San Francisco Bay area by 12Z Wednesday. A modest plume of moisture will generally remain focused along the occluding boundary near/offshore of California coastal areas through the period, but the mid-level cold core may begin to spread inland across northern through central California coastal areas by the end of the period. ...Lower Great Lakes region... Steep lapse rates beneath the lower/mid-tropospheric cold core will be maintained beyond 12Z this morning. Forecast soundings, mainly over/near the relatively warm lake waters (particularly near southeastern Lake Ontario coastal areas), suggest that this may continue to contribute to thermodynamic profiles potentially conducive to low-topped convection capable of producing lightning, possibly into the midday or early afternoon hours. ...California coast... Due to the occluding and weakening nature of the approaching surface cyclone, and its offshore forecast track, the potential for appreciable boundary-layer destabilization inland of coastal areas near San Francisco Bay appears quite low. While mid-level cooling ahead of the modest mid-level cold core (including 500 mb temperatures of -22 to -24C) may contribute to convective development capable of producing lightning offshore of coastal areas, lightning production with the convection may tend to wane as it reaches central California coastal areas late tonight into early Wednesday. ..Kerr.. 11/28/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1106 PM CST Mon Nov 27 2023 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across much of the U.S., today through tonight. ...Synopsis... Split westerlies emanating from the mid-latitude Pacific will continue to converge into broad, deep troughing east of the Great Plains into the western Atlantic. Within this regime, models indicate that one significant short wave perturbation, crossing the lower Great Lakes/upper Ohio Valley at the outset of the period, will fairly rapidly pivot across the northern Atlantic Seaboard by early this evening. However, broadly cyclonic northwesterly mid-level flow appears likely to linger across and east of the Mississippi Valley. Cool to cold, dry and stable conditions will generally be maintained beneath this regime, while downslope warming contributes to moderating temperatures across much of the Great Plains. Upstream, within a branch of westerlies across the southern mid-latitude eastern Pacific into the Southwest, mid-level troughing is forecast to dig across the California coast, with an embedded weakening low and associated occluding surface cyclone approaching the San Francisco Bay area by 12Z Wednesday. A modest plume of moisture will generally remain focused along the occluding boundary near/offshore of California coastal areas through the period, but the mid-level cold core may begin to spread inland across northern through central California coastal areas by the end of the period. ...Lower Great Lakes region... Steep lapse rates beneath the lower/mid-tropospheric cold core will be maintained beyond 12Z this morning. Forecast soundings, mainly over/near the relatively warm lake waters (particularly near southeastern Lake Ontario coastal areas), suggest that this may continue to contribute to thermodynamic profiles potentially conducive to low-topped convection capable of producing lightning, possibly into the midday or early afternoon hours. ...California coast... Due to the occluding and weakening nature of the approaching surface cyclone, and its offshore forecast track, the potential for appreciable boundary-layer destabilization inland of coastal areas near San Francisco Bay appears quite low. While mid-level cooling ahead of the modest mid-level cold core (including 500 mb temperatures of -22 to -24C) may contribute to convective development capable of producing lightning offshore of coastal areas, lightning production with the convection may tend to wane as it reaches central California coastal areas late tonight into early Wednesday. ..Kerr.. 11/28/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1106 PM CST Mon Nov 27 2023 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across much of the U.S., today through tonight. ...Synopsis... Split westerlies emanating from the mid-latitude Pacific will continue to converge into broad, deep troughing east of the Great Plains into the western Atlantic. Within this regime, models indicate that one significant short wave perturbation, crossing the lower Great Lakes/upper Ohio Valley at the outset of the period, will fairly rapidly pivot across the northern Atlantic Seaboard by early this evening. However, broadly cyclonic northwesterly mid-level flow appears likely to linger across and east of the Mississippi Valley. Cool to cold, dry and stable conditions will generally be maintained beneath this regime, while downslope warming contributes to moderating temperatures across much of the Great Plains. Upstream, within a branch of westerlies across the southern mid-latitude eastern Pacific into the Southwest, mid-level troughing is forecast to dig across the California coast, with an embedded weakening low and associated occluding surface cyclone approaching the San Francisco Bay area by 12Z Wednesday. A modest plume of moisture will generally remain focused along the occluding boundary near/offshore of California coastal areas through the period, but the mid-level cold core may begin to spread inland across northern through central California coastal areas by the end of the period. ...Lower Great Lakes region... Steep lapse rates beneath the lower/mid-tropospheric cold core will be maintained beyond 12Z this morning. Forecast soundings, mainly over/near the relatively warm lake waters (particularly near southeastern Lake Ontario coastal areas), suggest that this may continue to contribute to thermodynamic profiles potentially conducive to low-topped convection capable of producing lightning, possibly into the midday or early afternoon hours. ...California coast... Due to the occluding and weakening nature of the approaching surface cyclone, and its offshore forecast track, the potential for appreciable boundary-layer destabilization inland of coastal areas near San Francisco Bay appears quite low. While mid-level cooling ahead of the modest mid-level cold core (including 500 mb temperatures of -22 to -24C) may contribute to convective development capable of producing lightning offshore of coastal areas, lightning production with the convection may tend to wane as it reaches central California coastal areas late tonight into early Wednesday. ..Kerr.. 11/28/2023 Read more