Severe Storms

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

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

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 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0645 PM CST Mon Nov 27 2023 Valid 280100Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms will remain negligible across much of the U.S. through tonight. ...01Z Update... ...Lower Great Lakes vicinity... Relatively low/warm equilibrium levels, for lifted parcels contributing to ongoing convective snow bands within deep-layer cyclonic flow, have generally precluded the development of lightning to this point. However, a few lightning flashes were noted between 22-23Z along coastal Ontario to the southeast of Lake Huron. This appeared to coincide with the leading edge of southeastward advecting air characterized by temperatures of -22 to -24C around 700 mb. As this cooling overspreads the remainder of the lower Great Lakes vicinity by 06-09Z, there may be sufficient rising/cooling of equilibrium levels to support convection capable of producing lightning, mainly over southern/eastern portions of Lakes Erie/Ontario and immediate adjacent coastal areas. ..Kerr.. 11/28/2023 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0645 PM CST Mon Nov 27 2023 Valid 280100Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms will remain negligible across much of the U.S. through tonight. ...01Z Update... ...Lower Great Lakes vicinity... Relatively low/warm equilibrium levels, for lifted parcels contributing to ongoing convective snow bands within deep-layer cyclonic flow, have generally precluded the development of lightning to this point. However, a few lightning flashes were noted between 22-23Z along coastal Ontario to the southeast of Lake Huron. This appeared to coincide with the leading edge of southeastward advecting air characterized by temperatures of -22 to -24C around 700 mb. As this cooling overspreads the remainder of the lower Great Lakes vicinity by 06-09Z, there may be sufficient rising/cooling of equilibrium levels to support convection capable of producing lightning, mainly over southern/eastern portions of Lakes Erie/Ontario and immediate adjacent coastal areas. ..Kerr.. 11/28/2023 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0645 PM CST Mon Nov 27 2023 Valid 280100Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms will remain negligible across much of the U.S. through tonight. ...01Z Update... ...Lower Great Lakes vicinity... Relatively low/warm equilibrium levels, for lifted parcels contributing to ongoing convective snow bands within deep-layer cyclonic flow, have generally precluded the development of lightning to this point. However, a few lightning flashes were noted between 22-23Z along coastal Ontario to the southeast of Lake Huron. This appeared to coincide with the leading edge of southeastward advecting air characterized by temperatures of -22 to -24C around 700 mb. As this cooling overspreads the remainder of the lower Great Lakes vicinity by 06-09Z, there may be sufficient rising/cooling of equilibrium levels to support convection capable of producing lightning, mainly over southern/eastern portions of Lakes Erie/Ontario and immediate adjacent coastal areas. ..Kerr.. 11/28/2023 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0645 PM CST Mon Nov 27 2023 Valid 280100Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms will remain negligible across much of the U.S. through tonight. ...01Z Update... ...Lower Great Lakes vicinity... Relatively low/warm equilibrium levels, for lifted parcels contributing to ongoing convective snow bands within deep-layer cyclonic flow, have generally precluded the development of lightning to this point. However, a few lightning flashes were noted between 22-23Z along coastal Ontario to the southeast of Lake Huron. This appeared to coincide with the leading edge of southeastward advecting air characterized by temperatures of -22 to -24C around 700 mb. As this cooling overspreads the remainder of the lower Great Lakes vicinity by 06-09Z, there may be sufficient rising/cooling of equilibrium levels to support convection capable of producing lightning, mainly over southern/eastern portions of Lakes Erie/Ontario and immediate adjacent coastal areas. ..Kerr.. 11/28/2023 Read more

No watches are valid as of Mon Nov 27 22:28:02 UTC 2023.