Aggregator

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1100 PM CST Sun Nov 26 2023 Valid 271200Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across much of the U.S. today, although some lightning is possible in developing bands of snow across parts of the upper into lower Great Lakes vicinity by tonight. ...Synopsis... Split westerlies emanating from the mid-latitude Pacific continue to converge east of the Rockies, where some further amplification of northern branch large-scale troughing is possible, toward the southern mid latitudes. As this troughing slowly shifts east of the Mississippi Valley, through the Canadian Maritimes and waters offshore of the Atlantic Seaboard, at least some suppression of mid-level heights is forecast on the northern periphery of subtropical ridging centered over the Caribbean. Beneath this regime, a significant cold front, trailing a deepening occluded surface cyclone migrating to the east and northeast of James Bay, is forecast to advance into the Bahamas, northwest Caribbean and southwestern Gulf of Mexico before stalling. In its wake, generally dry/stable conditions will be maintained across much of the U.S. into 12Z Tuesday. ...Lake Superior into lower Great Lakes... While stronger mid-level height falls (associated with a pair of short wave perturbations embedded within the larger-scale cyclonic flow), spread eastward and northeastward, away from the Great Lakes region, models indicate that another consolidating short wave perturbation will dig southeast of the Upper Midwest through the upper Ohio Valley/Mid Atlantic by late Monday night. As it does, deep-layer cyclonic flow likely will be maintained across much of Lake Superior through the lower Great Lakes vicinity, where the southeastward advecting lower/mid-tropospheric cold core (including -20 to -24C around 700 mb) will contribute to steepening lapse rates above the relatively warm lake waters. Associated destabilization is forecast to support developing bands of snow, with forecast soundings indicating the evolution of thermodynamic profiles which could potentially become conducive to lightning, particularly by tonight across and to the immediate lee of the lower Great Lakes. ..Kerr/Weinman.. 11/27/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1100 PM CST Sun Nov 26 2023 Valid 271200Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across much of the U.S. today, although some lightning is possible in developing bands of snow across parts of the upper into lower Great Lakes vicinity by tonight. ...Synopsis... Split westerlies emanating from the mid-latitude Pacific continue to converge east of the Rockies, where some further amplification of northern branch large-scale troughing is possible, toward the southern mid latitudes. As this troughing slowly shifts east of the Mississippi Valley, through the Canadian Maritimes and waters offshore of the Atlantic Seaboard, at least some suppression of mid-level heights is forecast on the northern periphery of subtropical ridging centered over the Caribbean. Beneath this regime, a significant cold front, trailing a deepening occluded surface cyclone migrating to the east and northeast of James Bay, is forecast to advance into the Bahamas, northwest Caribbean and southwestern Gulf of Mexico before stalling. In its wake, generally dry/stable conditions will be maintained across much of the U.S. into 12Z Tuesday. ...Lake Superior into lower Great Lakes... While stronger mid-level height falls (associated with a pair of short wave perturbations embedded within the larger-scale cyclonic flow), spread eastward and northeastward, away from the Great Lakes region, models indicate that another consolidating short wave perturbation will dig southeast of the Upper Midwest through the upper Ohio Valley/Mid Atlantic by late Monday night. As it does, deep-layer cyclonic flow likely will be maintained across much of Lake Superior through the lower Great Lakes vicinity, where the southeastward advecting lower/mid-tropospheric cold core (including -20 to -24C around 700 mb) will contribute to steepening lapse rates above the relatively warm lake waters. Associated destabilization is forecast to support developing bands of snow, with forecast soundings indicating the evolution of thermodynamic profiles which could potentially become conducive to lightning, particularly by tonight across and to the immediate lee of the lower Great Lakes. ..Kerr/Weinman.. 11/27/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1100 PM CST Sun Nov 26 2023 Valid 271200Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across much of the U.S. today, although some lightning is possible in developing bands of snow across parts of the upper into lower Great Lakes vicinity by tonight. ...Synopsis... Split westerlies emanating from the mid-latitude Pacific continue to converge east of the Rockies, where some further amplification of northern branch large-scale troughing is possible, toward the southern mid latitudes. As this troughing slowly shifts east of the Mississippi Valley, through the Canadian Maritimes and waters offshore of the Atlantic Seaboard, at least some suppression of mid-level heights is forecast on the northern periphery of subtropical ridging centered over the Caribbean. Beneath this regime, a significant cold front, trailing a deepening occluded surface cyclone migrating to the east and northeast of James Bay, is forecast to advance into the Bahamas, northwest Caribbean and southwestern Gulf of Mexico before stalling. In its wake, generally dry/stable conditions will be maintained across much of the U.S. into 12Z Tuesday. ...Lake Superior into lower Great Lakes... While stronger mid-level height falls (associated with a pair of short wave perturbations embedded within the larger-scale cyclonic flow), spread eastward and northeastward, away from the Great Lakes region, models indicate that another consolidating short wave perturbation will dig southeast of the Upper Midwest through the upper Ohio Valley/Mid Atlantic by late Monday night. As it does, deep-layer cyclonic flow likely will be maintained across much of Lake Superior through the lower Great Lakes vicinity, where the southeastward advecting lower/mid-tropospheric cold core (including -20 to -24C around 700 mb) will contribute to steepening lapse rates above the relatively warm lake waters. Associated destabilization is forecast to support developing bands of snow, with forecast soundings indicating the evolution of thermodynamic profiles which could potentially become conducive to lightning, particularly by tonight across and to the immediate lee of the lower Great Lakes. ..Kerr/Weinman.. 11/27/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1100 PM CST Sun Nov 26 2023 Valid 271200Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across much of the U.S. today, although some lightning is possible in developing bands of snow across parts of the upper into lower Great Lakes vicinity by tonight. ...Synopsis... Split westerlies emanating from the mid-latitude Pacific continue to converge east of the Rockies, where some further amplification of northern branch large-scale troughing is possible, toward the southern mid latitudes. As this troughing slowly shifts east of the Mississippi Valley, through the Canadian Maritimes and waters offshore of the Atlantic Seaboard, at least some suppression of mid-level heights is forecast on the northern periphery of subtropical ridging centered over the Caribbean. Beneath this regime, a significant cold front, trailing a deepening occluded surface cyclone migrating to the east and northeast of James Bay, is forecast to advance into the Bahamas, northwest Caribbean and southwestern Gulf of Mexico before stalling. In its wake, generally dry/stable conditions will be maintained across much of the U.S. into 12Z Tuesday. ...Lake Superior into lower Great Lakes... While stronger mid-level height falls (associated with a pair of short wave perturbations embedded within the larger-scale cyclonic flow), spread eastward and northeastward, away from the Great Lakes region, models indicate that another consolidating short wave perturbation will dig southeast of the Upper Midwest through the upper Ohio Valley/Mid Atlantic by late Monday night. As it does, deep-layer cyclonic flow likely will be maintained across much of Lake Superior through the lower Great Lakes vicinity, where the southeastward advecting lower/mid-tropospheric cold core (including -20 to -24C around 700 mb) will contribute to steepening lapse rates above the relatively warm lake waters. Associated destabilization is forecast to support developing bands of snow, with forecast soundings indicating the evolution of thermodynamic profiles which could potentially become conducive to lightning, particularly by tonight across and to the immediate lee of the lower Great Lakes. ..Kerr/Weinman.. 11/27/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1100 PM CST Sun Nov 26 2023 Valid 271200Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across much of the U.S. today, although some lightning is possible in developing bands of snow across parts of the upper into lower Great Lakes vicinity by tonight. ...Synopsis... Split westerlies emanating from the mid-latitude Pacific continue to converge east of the Rockies, where some further amplification of northern branch large-scale troughing is possible, toward the southern mid latitudes. As this troughing slowly shifts east of the Mississippi Valley, through the Canadian Maritimes and waters offshore of the Atlantic Seaboard, at least some suppression of mid-level heights is forecast on the northern periphery of subtropical ridging centered over the Caribbean. Beneath this regime, a significant cold front, trailing a deepening occluded surface cyclone migrating to the east and northeast of James Bay, is forecast to advance into the Bahamas, northwest Caribbean and southwestern Gulf of Mexico before stalling. In its wake, generally dry/stable conditions will be maintained across much of the U.S. into 12Z Tuesday. ...Lake Superior into lower Great Lakes... While stronger mid-level height falls (associated with a pair of short wave perturbations embedded within the larger-scale cyclonic flow), spread eastward and northeastward, away from the Great Lakes region, models indicate that another consolidating short wave perturbation will dig southeast of the Upper Midwest through the upper Ohio Valley/Mid Atlantic by late Monday night. As it does, deep-layer cyclonic flow likely will be maintained across much of Lake Superior through the lower Great Lakes vicinity, where the southeastward advecting lower/mid-tropospheric cold core (including -20 to -24C around 700 mb) will contribute to steepening lapse rates above the relatively warm lake waters. Associated destabilization is forecast to support developing bands of snow, with forecast soundings indicating the evolution of thermodynamic profiles which could potentially become conducive to lightning, particularly by tonight across and to the immediate lee of the lower Great Lakes. ..Kerr/Weinman.. 11/27/2023 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0648 PM CST Sun Nov 26 2023 Valid 270100Z - 271200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across the U.S. through tonight. ...01Z Update... While a primary surface cyclone slowly deepens northeast of the upper Great Lakes, toward James Bay, a more compact secondary low is forecast to modestly deepen while migrating northward from the northern Mid Atlantic coast vicinity into New England overnight. A weaker trailing frontal low is now beginning to redevelop east-northeast of the northern Florida coast. Substantive pre-frontal low-level moisture return remains confined to areas offshore of the south Atlantic coast. While further north-northeastward advection of this moisture is probable overnight, it appears that this will remain well east of the northern Atlantic Seaboard, as the cold front advances offshore, in the wake of the low migrating into New England. Due to the initially limited low-level moisture return, and the lack of stronger cooling aloft (which is still focused across the Great Lakes into Ohio Valley vicinity), the development of thermodynamic profiles conducive to convection capable of producing lightning appears unlikely tonight across northern Mid Atlantic coastal areas, southern New England and adjacent coastal waters. ..Kerr.. 11/27/2023 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0648 PM CST Sun Nov 26 2023 Valid 270100Z - 271200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across the U.S. through tonight. ...01Z Update... While a primary surface cyclone slowly deepens northeast of the upper Great Lakes, toward James Bay, a more compact secondary low is forecast to modestly deepen while migrating northward from the northern Mid Atlantic coast vicinity into New England overnight. A weaker trailing frontal low is now beginning to redevelop east-northeast of the northern Florida coast. Substantive pre-frontal low-level moisture return remains confined to areas offshore of the south Atlantic coast. While further north-northeastward advection of this moisture is probable overnight, it appears that this will remain well east of the northern Atlantic Seaboard, as the cold front advances offshore, in the wake of the low migrating into New England. Due to the initially limited low-level moisture return, and the lack of stronger cooling aloft (which is still focused across the Great Lakes into Ohio Valley vicinity), the development of thermodynamic profiles conducive to convection capable of producing lightning appears unlikely tonight across northern Mid Atlantic coastal areas, southern New England and adjacent coastal waters. ..Kerr.. 11/27/2023 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0648 PM CST Sun Nov 26 2023 Valid 270100Z - 271200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across the U.S. through tonight. ...01Z Update... While a primary surface cyclone slowly deepens northeast of the upper Great Lakes, toward James Bay, a more compact secondary low is forecast to modestly deepen while migrating northward from the northern Mid Atlantic coast vicinity into New England overnight. A weaker trailing frontal low is now beginning to redevelop east-northeast of the northern Florida coast. Substantive pre-frontal low-level moisture return remains confined to areas offshore of the south Atlantic coast. While further north-northeastward advection of this moisture is probable overnight, it appears that this will remain well east of the northern Atlantic Seaboard, as the cold front advances offshore, in the wake of the low migrating into New England. Due to the initially limited low-level moisture return, and the lack of stronger cooling aloft (which is still focused across the Great Lakes into Ohio Valley vicinity), the development of thermodynamic profiles conducive to convection capable of producing lightning appears unlikely tonight across northern Mid Atlantic coastal areas, southern New England and adjacent coastal waters. ..Kerr.. 11/27/2023 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0648 PM CST Sun Nov 26 2023 Valid 270100Z - 271200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across the U.S. through tonight. ...01Z Update... While a primary surface cyclone slowly deepens northeast of the upper Great Lakes, toward James Bay, a more compact secondary low is forecast to modestly deepen while migrating northward from the northern Mid Atlantic coast vicinity into New England overnight. A weaker trailing frontal low is now beginning to redevelop east-northeast of the northern Florida coast. Substantive pre-frontal low-level moisture return remains confined to areas offshore of the south Atlantic coast. While further north-northeastward advection of this moisture is probable overnight, it appears that this will remain well east of the northern Atlantic Seaboard, as the cold front advances offshore, in the wake of the low migrating into New England. Due to the initially limited low-level moisture return, and the lack of stronger cooling aloft (which is still focused across the Great Lakes into Ohio Valley vicinity), the development of thermodynamic profiles conducive to convection capable of producing lightning appears unlikely tonight across northern Mid Atlantic coastal areas, southern New England and adjacent coastal waters. ..Kerr.. 11/27/2023 Read more

No watches are valid as of Sun Nov 26 22:20:02 UTC 2023.

No Mesoscale Discussions are in effect as of Sun Nov 26 22:20:02 UTC 2023.

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0331 PM CST Sun Nov 26 2023 Valid 281200Z - 041200Z Multiple mid-level troughs are poised to overspread the CONUS through the week, with surface high pressure and associated cool conditions prevailing over most of the U.S. through at least Day 4/Wednesday. By Day 5/Thursday, surface cyclone development is likely across the southern Plains, shifting eastward as the weekend approaches, resulting in wet conditions. Thereafter, a moist low-level airmass will reside across the southeast quadrant of the U.S. while cool and dry conditions prevail through most of the rest of the CONUS. With the exception of localized, brief wildfire conditions possible with dry downslope flow along the High Plains, no significant wildfire-spread potential appears evident over the U.S. this week. ..Squitieri.. 11/26/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0331 PM CST Sun Nov 26 2023 Valid 281200Z - 041200Z Multiple mid-level troughs are poised to overspread the CONUS through the week, with surface high pressure and associated cool conditions prevailing over most of the U.S. through at least Day 4/Wednesday. By Day 5/Thursday, surface cyclone development is likely across the southern Plains, shifting eastward as the weekend approaches, resulting in wet conditions. Thereafter, a moist low-level airmass will reside across the southeast quadrant of the U.S. while cool and dry conditions prevail through most of the rest of the CONUS. With the exception of localized, brief wildfire conditions possible with dry downslope flow along the High Plains, no significant wildfire-spread potential appears evident over the U.S. this week. ..Squitieri.. 11/26/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0331 PM CST Sun Nov 26 2023 Valid 281200Z - 041200Z Multiple mid-level troughs are poised to overspread the CONUS through the week, with surface high pressure and associated cool conditions prevailing over most of the U.S. through at least Day 4/Wednesday. By Day 5/Thursday, surface cyclone development is likely across the southern Plains, shifting eastward as the weekend approaches, resulting in wet conditions. Thereafter, a moist low-level airmass will reside across the southeast quadrant of the U.S. while cool and dry conditions prevail through most of the rest of the CONUS. With the exception of localized, brief wildfire conditions possible with dry downslope flow along the High Plains, no significant wildfire-spread potential appears evident over the U.S. this week. ..Squitieri.. 11/26/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0331 PM CST Sun Nov 26 2023 Valid 281200Z - 041200Z Multiple mid-level troughs are poised to overspread the CONUS through the week, with surface high pressure and associated cool conditions prevailing over most of the U.S. through at least Day 4/Wednesday. By Day 5/Thursday, surface cyclone development is likely across the southern Plains, shifting eastward as the weekend approaches, resulting in wet conditions. Thereafter, a moist low-level airmass will reside across the southeast quadrant of the U.S. while cool and dry conditions prevail through most of the rest of the CONUS. With the exception of localized, brief wildfire conditions possible with dry downslope flow along the High Plains, no significant wildfire-spread potential appears evident over the U.S. this week. ..Squitieri.. 11/26/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0331 PM CST Sun Nov 26 2023 Valid 281200Z - 041200Z Multiple mid-level troughs are poised to overspread the CONUS through the week, with surface high pressure and associated cool conditions prevailing over most of the U.S. through at least Day 4/Wednesday. By Day 5/Thursday, surface cyclone development is likely across the southern Plains, shifting eastward as the weekend approaches, resulting in wet conditions. Thereafter, a moist low-level airmass will reside across the southeast quadrant of the U.S. while cool and dry conditions prevail through most of the rest of the CONUS. With the exception of localized, brief wildfire conditions possible with dry downslope flow along the High Plains, no significant wildfire-spread potential appears evident over the U.S. this week. ..Squitieri.. 11/26/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0158 PM CST Sun Nov 26 2023 Valid 262000Z - 271200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected. ...Discussion... Primary change has been to trim the northwest extent of the thunder area in the Southeast based on latest obs. Low probability for a transient supercell remains evident in the 22-02Z time frame, mainly along the west-central FL coast near the quasi-stationary front draped from 30 SW OCF to around DAB. To the south of this front, the 18Z RAP remains on the aggressive end of guidance, suggesting the intrusion of MLCAPE in excess of 1000 J/kg from the northeast Gulf. Convection within the low-level warm theta-e advection regime preceding this potential buoyancy intrusion is ongoing west-southwest of Tampa Bay. This activity should shift east-northeast over the next few hours within a wind profile marginally conducive to low-level updraft rotation. But bulk of 12Z HREF and NSSL-MPAS guidance and the 18Z HRRR are insistent that convection will weaken as it moves inland over the peninsula and generally subside after mid-evening. ..Grams.. 11/26/2023 .PREV DISCUSSION... /ISSUED 1006 AM CST Sun Nov 26 2023/ ...Synopsis... Thunderstorm potential for the remainder of today/tonight will be focused around two compact coastal lows - one over the northeastern Gulf of Mexico and another migrating northeastward along the Mid-Atlantic/New England coast. ...Northeastern Gulf Coast/FL Big Bend region... Morning soundings sampled 50-60 knot mid-level flow along the FL Gulf coast, which should be supportive of organized convection given weak southeasterly low-level flow. However, recent lightning and radar trends suggest ongoing offshore convection within a relatively buoyant air mass is struggling to maintain intensity/organization. This is likely attributable to poor mid-level lapse rates (also sampled by morning soundings) and somewhat weak forcing for ascent. Ongoing precipitation across central/northern FL will likely inhibit the northward progression of higher quality low-level moisture (dewpoints >= 70 F), and may maintain a slight cold advection regime across northern FL for much of the day. Combined with the modest lapse-rate environment, this should modulate surface-based buoyancy values over land. Consequently, confidence remains low that any organized convection that can develop over the northeastern Gulf waters will maintain intensity upon landfall along the Big Bend coast. Trends will continue to be monitored through the afternoon as a low-end severe threat may materialize if coastal buoyancy exceeds current expectations. ...Mid-Atlantic/New England Coast... A few lightning flashes will be possible overnight as a warm advection regime associated with the coastal low overspreads the Mid-Atlantic/New England coast. Despite strong flow aloft, the elevated nature of any convection, combined with very modest buoyancy profiles, should preclude organized thunderstorms. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0158 PM CST Sun Nov 26 2023 Valid 262000Z - 271200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected. ...Discussion... Primary change has been to trim the northwest extent of the thunder area in the Southeast based on latest obs. Low probability for a transient supercell remains evident in the 22-02Z time frame, mainly along the west-central FL coast near the quasi-stationary front draped from 30 SW OCF to around DAB. To the south of this front, the 18Z RAP remains on the aggressive end of guidance, suggesting the intrusion of MLCAPE in excess of 1000 J/kg from the northeast Gulf. Convection within the low-level warm theta-e advection regime preceding this potential buoyancy intrusion is ongoing west-southwest of Tampa Bay. This activity should shift east-northeast over the next few hours within a wind profile marginally conducive to low-level updraft rotation. But bulk of 12Z HREF and NSSL-MPAS guidance and the 18Z HRRR are insistent that convection will weaken as it moves inland over the peninsula and generally subside after mid-evening. ..Grams.. 11/26/2023 .PREV DISCUSSION... /ISSUED 1006 AM CST Sun Nov 26 2023/ ...Synopsis... Thunderstorm potential for the remainder of today/tonight will be focused around two compact coastal lows - one over the northeastern Gulf of Mexico and another migrating northeastward along the Mid-Atlantic/New England coast. ...Northeastern Gulf Coast/FL Big Bend region... Morning soundings sampled 50-60 knot mid-level flow along the FL Gulf coast, which should be supportive of organized convection given weak southeasterly low-level flow. However, recent lightning and radar trends suggest ongoing offshore convection within a relatively buoyant air mass is struggling to maintain intensity/organization. This is likely attributable to poor mid-level lapse rates (also sampled by morning soundings) and somewhat weak forcing for ascent. Ongoing precipitation across central/northern FL will likely inhibit the northward progression of higher quality low-level moisture (dewpoints >= 70 F), and may maintain a slight cold advection regime across northern FL for much of the day. Combined with the modest lapse-rate environment, this should modulate surface-based buoyancy values over land. Consequently, confidence remains low that any organized convection that can develop over the northeastern Gulf waters will maintain intensity upon landfall along the Big Bend coast. Trends will continue to be monitored through the afternoon as a low-end severe threat may materialize if coastal buoyancy exceeds current expectations. ...Mid-Atlantic/New England Coast... A few lightning flashes will be possible overnight as a warm advection regime associated with the coastal low overspreads the Mid-Atlantic/New England coast. Despite strong flow aloft, the elevated nature of any convection, combined with very modest buoyancy profiles, should preclude organized thunderstorms. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0158 PM CST Sun Nov 26 2023 Valid 262000Z - 271200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected. ...Discussion... Primary change has been to trim the northwest extent of the thunder area in the Southeast based on latest obs. Low probability for a transient supercell remains evident in the 22-02Z time frame, mainly along the west-central FL coast near the quasi-stationary front draped from 30 SW OCF to around DAB. To the south of this front, the 18Z RAP remains on the aggressive end of guidance, suggesting the intrusion of MLCAPE in excess of 1000 J/kg from the northeast Gulf. Convection within the low-level warm theta-e advection regime preceding this potential buoyancy intrusion is ongoing west-southwest of Tampa Bay. This activity should shift east-northeast over the next few hours within a wind profile marginally conducive to low-level updraft rotation. But bulk of 12Z HREF and NSSL-MPAS guidance and the 18Z HRRR are insistent that convection will weaken as it moves inland over the peninsula and generally subside after mid-evening. ..Grams.. 11/26/2023 .PREV DISCUSSION... /ISSUED 1006 AM CST Sun Nov 26 2023/ ...Synopsis... Thunderstorm potential for the remainder of today/tonight will be focused around two compact coastal lows - one over the northeastern Gulf of Mexico and another migrating northeastward along the Mid-Atlantic/New England coast. ...Northeastern Gulf Coast/FL Big Bend region... Morning soundings sampled 50-60 knot mid-level flow along the FL Gulf coast, which should be supportive of organized convection given weak southeasterly low-level flow. However, recent lightning and radar trends suggest ongoing offshore convection within a relatively buoyant air mass is struggling to maintain intensity/organization. This is likely attributable to poor mid-level lapse rates (also sampled by morning soundings) and somewhat weak forcing for ascent. Ongoing precipitation across central/northern FL will likely inhibit the northward progression of higher quality low-level moisture (dewpoints >= 70 F), and may maintain a slight cold advection regime across northern FL for much of the day. Combined with the modest lapse-rate environment, this should modulate surface-based buoyancy values over land. Consequently, confidence remains low that any organized convection that can develop over the northeastern Gulf waters will maintain intensity upon landfall along the Big Bend coast. Trends will continue to be monitored through the afternoon as a low-end severe threat may materialize if coastal buoyancy exceeds current expectations. ...Mid-Atlantic/New England Coast... A few lightning flashes will be possible overnight as a warm advection regime associated with the coastal low overspreads the Mid-Atlantic/New England coast. Despite strong flow aloft, the elevated nature of any convection, combined with very modest buoyancy profiles, should preclude organized thunderstorms. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0158 PM CST Sun Nov 26 2023 Valid 262000Z - 271200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected. ...Discussion... Primary change has been to trim the northwest extent of the thunder area in the Southeast based on latest obs. Low probability for a transient supercell remains evident in the 22-02Z time frame, mainly along the west-central FL coast near the quasi-stationary front draped from 30 SW OCF to around DAB. To the south of this front, the 18Z RAP remains on the aggressive end of guidance, suggesting the intrusion of MLCAPE in excess of 1000 J/kg from the northeast Gulf. Convection within the low-level warm theta-e advection regime preceding this potential buoyancy intrusion is ongoing west-southwest of Tampa Bay. This activity should shift east-northeast over the next few hours within a wind profile marginally conducive to low-level updraft rotation. But bulk of 12Z HREF and NSSL-MPAS guidance and the 18Z HRRR are insistent that convection will weaken as it moves inland over the peninsula and generally subside after mid-evening. ..Grams.. 11/26/2023 .PREV DISCUSSION... /ISSUED 1006 AM CST Sun Nov 26 2023/ ...Synopsis... Thunderstorm potential for the remainder of today/tonight will be focused around two compact coastal lows - one over the northeastern Gulf of Mexico and another migrating northeastward along the Mid-Atlantic/New England coast. ...Northeastern Gulf Coast/FL Big Bend region... Morning soundings sampled 50-60 knot mid-level flow along the FL Gulf coast, which should be supportive of organized convection given weak southeasterly low-level flow. However, recent lightning and radar trends suggest ongoing offshore convection within a relatively buoyant air mass is struggling to maintain intensity/organization. This is likely attributable to poor mid-level lapse rates (also sampled by morning soundings) and somewhat weak forcing for ascent. Ongoing precipitation across central/northern FL will likely inhibit the northward progression of higher quality low-level moisture (dewpoints >= 70 F), and may maintain a slight cold advection regime across northern FL for much of the day. Combined with the modest lapse-rate environment, this should modulate surface-based buoyancy values over land. Consequently, confidence remains low that any organized convection that can develop over the northeastern Gulf waters will maintain intensity upon landfall along the Big Bend coast. Trends will continue to be monitored through the afternoon as a low-end severe threat may materialize if coastal buoyancy exceeds current expectations. ...Mid-Atlantic/New England Coast... A few lightning flashes will be possible overnight as a warm advection regime associated with the coastal low overspreads the Mid-Atlantic/New England coast. Despite strong flow aloft, the elevated nature of any convection, combined with very modest buoyancy profiles, should preclude organized thunderstorms. Read more