Severe Storms

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0317 AM CST Sat Dec 09 2023 Valid 121200Z - 171200Z ...DISCUSSION... Severe potential appears likely to remain negligible for several days in the wake of this weekend's cold front progressing across the Gulf Coast and the Atlantic Seaboard. Above-average agreement exists with the establishment of a surface anticyclone over the southern Appalachians vicinity on D3 into D4, and remaining anchored in this region through at least D7. This will yield predominant easterly surface winds over the Gulf and FL Peninsula, with gradual airmass modification. Next weekend, deterministic 00Z ECMWF, GFS, and CMC suggest potential for eastern Gulf or South Atlantic Coast cyclogenesis. This may occur in response to an upper low, that initially develops over the Southwest mid-week, being kicked east and subsequently amplifying towards the Deep South. Very large spread in timing and track, in addition to only a minority of ECMWF ensemble/GEFS members supporting such a scenario renders low confidence in predictability for the D8-10 time frame. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0317 AM CST Sat Dec 09 2023 Valid 121200Z - 171200Z ...DISCUSSION... Severe potential appears likely to remain negligible for several days in the wake of this weekend's cold front progressing across the Gulf Coast and the Atlantic Seaboard. Above-average agreement exists with the establishment of a surface anticyclone over the southern Appalachians vicinity on D3 into D4, and remaining anchored in this region through at least D7. This will yield predominant easterly surface winds over the Gulf and FL Peninsula, with gradual airmass modification. Next weekend, deterministic 00Z ECMWF, GFS, and CMC suggest potential for eastern Gulf or South Atlantic Coast cyclogenesis. This may occur in response to an upper low, that initially develops over the Southwest mid-week, being kicked east and subsequently amplifying towards the Deep South. Very large spread in timing and track, in addition to only a minority of ECMWF ensemble/GEFS members supporting such a scenario renders low confidence in predictability for the D8-10 time frame. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0317 AM CST Sat Dec 09 2023 Valid 121200Z - 171200Z ...DISCUSSION... Severe potential appears likely to remain negligible for several days in the wake of this weekend's cold front progressing across the Gulf Coast and the Atlantic Seaboard. Above-average agreement exists with the establishment of a surface anticyclone over the southern Appalachians vicinity on D3 into D4, and remaining anchored in this region through at least D7. This will yield predominant easterly surface winds over the Gulf and FL Peninsula, with gradual airmass modification. Next weekend, deterministic 00Z ECMWF, GFS, and CMC suggest potential for eastern Gulf or South Atlantic Coast cyclogenesis. This may occur in response to an upper low, that initially develops over the Southwest mid-week, being kicked east and subsequently amplifying towards the Deep South. Very large spread in timing and track, in addition to only a minority of ECMWF ensemble/GEFS members supporting such a scenario renders low confidence in predictability for the D8-10 time frame. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0317 AM CST Sat Dec 09 2023 Valid 121200Z - 171200Z ...DISCUSSION... Severe potential appears likely to remain negligible for several days in the wake of this weekend's cold front progressing across the Gulf Coast and the Atlantic Seaboard. Above-average agreement exists with the establishment of a surface anticyclone over the southern Appalachians vicinity on D3 into D4, and remaining anchored in this region through at least D7. This will yield predominant easterly surface winds over the Gulf and FL Peninsula, with gradual airmass modification. Next weekend, deterministic 00Z ECMWF, GFS, and CMC suggest potential for eastern Gulf or South Atlantic Coast cyclogenesis. This may occur in response to an upper low, that initially develops over the Southwest mid-week, being kicked east and subsequently amplifying towards the Deep South. Very large spread in timing and track, in addition to only a minority of ECMWF ensemble/GEFS members supporting such a scenario renders low confidence in predictability for the D8-10 time frame. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0317 AM CST Sat Dec 09 2023 Valid 121200Z - 171200Z ...DISCUSSION... Severe potential appears likely to remain negligible for several days in the wake of this weekend's cold front progressing across the Gulf Coast and the Atlantic Seaboard. Above-average agreement exists with the establishment of a surface anticyclone over the southern Appalachians vicinity on D3 into D4, and remaining anchored in this region through at least D7. This will yield predominant easterly surface winds over the Gulf and FL Peninsula, with gradual airmass modification. Next weekend, deterministic 00Z ECMWF, GFS, and CMC suggest potential for eastern Gulf or South Atlantic Coast cyclogenesis. This may occur in response to an upper low, that initially develops over the Southwest mid-week, being kicked east and subsequently amplifying towards the Deep South. Very large spread in timing and track, in addition to only a minority of ECMWF ensemble/GEFS members supporting such a scenario renders low confidence in predictability for the D8-10 time frame. Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0155 AM CST Sat Dec 09 2023 Valid 111200Z - 121200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorm probabilities appear to be less than 10 percent on Monday. ...Discussion... Substantial cyclogenesis late D2 should persist into early D3 with the surface low tracking near the New England coast to the Canadian Maritimes. An extremely strong low-level jet ahead of the cyclone, increasing to around 100 kts at 850 mb, may advect sufficient western Atlantic moisture to yield minimal elevated buoyancy. Both 00Z NAM and ECMWF forecast soundings indicate MUCAPE may reach 100 J/kg across Cape Cod to Downeast ME on Monday morning, but this appears to be largely inadequate for charge separation given weak lapse rates above 500 mb. Still, very strong forcing for ascent might support a few lightning flashes within heavier convective elements embedded amid a broad swath of rain. Elsewhere across the CONUS, with the surface cold front expected to clear the south FL Peninsula just prior to 12Z Monday, thunderstorm potential will be negligible. ..Grams.. 12/09/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0155 AM CST Sat Dec 09 2023 Valid 111200Z - 121200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorm probabilities appear to be less than 10 percent on Monday. ...Discussion... Substantial cyclogenesis late D2 should persist into early D3 with the surface low tracking near the New England coast to the Canadian Maritimes. An extremely strong low-level jet ahead of the cyclone, increasing to around 100 kts at 850 mb, may advect sufficient western Atlantic moisture to yield minimal elevated buoyancy. Both 00Z NAM and ECMWF forecast soundings indicate MUCAPE may reach 100 J/kg across Cape Cod to Downeast ME on Monday morning, but this appears to be largely inadequate for charge separation given weak lapse rates above 500 mb. Still, very strong forcing for ascent might support a few lightning flashes within heavier convective elements embedded amid a broad swath of rain. Elsewhere across the CONUS, with the surface cold front expected to clear the south FL Peninsula just prior to 12Z Monday, thunderstorm potential will be negligible. ..Grams.. 12/09/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0155 AM CST Sat Dec 09 2023 Valid 111200Z - 121200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorm probabilities appear to be less than 10 percent on Monday. ...Discussion... Substantial cyclogenesis late D2 should persist into early D3 with the surface low tracking near the New England coast to the Canadian Maritimes. An extremely strong low-level jet ahead of the cyclone, increasing to around 100 kts at 850 mb, may advect sufficient western Atlantic moisture to yield minimal elevated buoyancy. Both 00Z NAM and ECMWF forecast soundings indicate MUCAPE may reach 100 J/kg across Cape Cod to Downeast ME on Monday morning, but this appears to be largely inadequate for charge separation given weak lapse rates above 500 mb. Still, very strong forcing for ascent might support a few lightning flashes within heavier convective elements embedded amid a broad swath of rain. Elsewhere across the CONUS, with the surface cold front expected to clear the south FL Peninsula just prior to 12Z Monday, thunderstorm potential will be negligible. ..Grams.. 12/09/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0155 AM CST Sat Dec 09 2023 Valid 111200Z - 121200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorm probabilities appear to be less than 10 percent on Monday. ...Discussion... Substantial cyclogenesis late D2 should persist into early D3 with the surface low tracking near the New England coast to the Canadian Maritimes. An extremely strong low-level jet ahead of the cyclone, increasing to around 100 kts at 850 mb, may advect sufficient western Atlantic moisture to yield minimal elevated buoyancy. Both 00Z NAM and ECMWF forecast soundings indicate MUCAPE may reach 100 J/kg across Cape Cod to Downeast ME on Monday morning, but this appears to be largely inadequate for charge separation given weak lapse rates above 500 mb. Still, very strong forcing for ascent might support a few lightning flashes within heavier convective elements embedded amid a broad swath of rain. Elsewhere across the CONUS, with the surface cold front expected to clear the south FL Peninsula just prior to 12Z Monday, thunderstorm potential will be negligible. ..Grams.. 12/09/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0155 AM CST Sat Dec 09 2023 Valid 111200Z - 121200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorm probabilities appear to be less than 10 percent on Monday. ...Discussion... Substantial cyclogenesis late D2 should persist into early D3 with the surface low tracking near the New England coast to the Canadian Maritimes. An extremely strong low-level jet ahead of the cyclone, increasing to around 100 kts at 850 mb, may advect sufficient western Atlantic moisture to yield minimal elevated buoyancy. Both 00Z NAM and ECMWF forecast soundings indicate MUCAPE may reach 100 J/kg across Cape Cod to Downeast ME on Monday morning, but this appears to be largely inadequate for charge separation given weak lapse rates above 500 mb. Still, very strong forcing for ascent might support a few lightning flashes within heavier convective elements embedded amid a broad swath of rain. Elsewhere across the CONUS, with the surface cold front expected to clear the south FL Peninsula just prior to 12Z Monday, thunderstorm potential will be negligible. ..Grams.. 12/09/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0155 AM CST Sat Dec 09 2023 Valid 111200Z - 121200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorm probabilities appear to be less than 10 percent on Monday. ...Discussion... Substantial cyclogenesis late D2 should persist into early D3 with the surface low tracking near the New England coast to the Canadian Maritimes. An extremely strong low-level jet ahead of the cyclone, increasing to around 100 kts at 850 mb, may advect sufficient western Atlantic moisture to yield minimal elevated buoyancy. Both 00Z NAM and ECMWF forecast soundings indicate MUCAPE may reach 100 J/kg across Cape Cod to Downeast ME on Monday morning, but this appears to be largely inadequate for charge separation given weak lapse rates above 500 mb. Still, very strong forcing for ascent might support a few lightning flashes within heavier convective elements embedded amid a broad swath of rain. Elsewhere across the CONUS, with the surface cold front expected to clear the south FL Peninsula just prior to 12Z Monday, thunderstorm potential will be negligible. ..Grams.. 12/09/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1243 AM CST Sat Dec 09 2023 Valid 101200Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FL PANHANDLE TO THE DELMARVA... ...SUMMARY... Isolated severe thunderstorms will be possible through Sunday evening across parts of the Southeast States, mainly in the form of sporadic damaging winds and a few brief tornadoes. ...Synopsis... An amplified, positive-tilt upper trough from ON to east TX at 12Z Sunday will take on a neutral to slight negative tilt as a basal shortwave impulse rapidly ejects across the Deep South to the Lower Mid-Atlantic States. Intense mid-level southerlies will become asymmetrically confined ahead of the trough by early morning Monday. Surface cyclogenesis will occur from the central/southern Appalachians across the Northeast into southern New England, with greater deepening during the latter half of the period. ...FL Panhandle to the Delmarva... Overall scenario appears similar to prior days with a broad swath of low-probability tornado and severe thunderstorm wind evident from Sunday morning to evening across the Southeast States. A mesoscale corridor of greater tornado/wind threat may be highlighted in later outlooks, seemingly within the eastern SC to southeast VA vicinity. A swath of showers and embedded thunderstorms will likely be ongoing 12Z Sunday from western/central VA to the FL Panhandle, within the warm conveyor ahead of a surface cold front steadily progressing eastward. Morning severe potential should generally be confined to the FL/GA portion of the risk area, where mid 60s surface dew points should be more common ahead of the early-day convection. Diurnal diabatic heating is still expected to be muted, with extensive low-level moistening and resultant cloudiness anticipated. Consensus of guidance still suggests that a separate low-level warm theta-e advection regime from the western Atlantic will aid in a secondary swath of convective development by late morning into the afternoon across the eastern Carolinas. A corridor of somewhat greater surface heating may occur between both regimes which could yield a mesoscale area of MLCAPE from 500-1000 J/kg. Otherwise, amid weak mid-level lapse rates, much of the region should hold with MLCAPE at or below 500 J/kg. Low-level hodographs will be more favorably enlarged from the Carolinas northward. Should this become coincident with greater than meager buoyancy, a level 2-SLGT risk may be warranted for Sunday afternoon. More prominent strengthening of low-level southerlies will occur on Sunday night as cyclogenesis intensifies. However, the thermodynamic environment may be mostly to completely overturned by this time frame, given widespread convection. Guidance varies substantially in whether scant to meager surface-based buoyancy can still linger ahead of the cold front, mainly across eastern NC. Should this occur, a brief tornado/damaging-wind threat may be sustained through late evening. ..Grams.. 12/09/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1243 AM CST Sat Dec 09 2023 Valid 101200Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FL PANHANDLE TO THE DELMARVA... ...SUMMARY... Isolated severe thunderstorms will be possible through Sunday evening across parts of the Southeast States, mainly in the form of sporadic damaging winds and a few brief tornadoes. ...Synopsis... An amplified, positive-tilt upper trough from ON to east TX at 12Z Sunday will take on a neutral to slight negative tilt as a basal shortwave impulse rapidly ejects across the Deep South to the Lower Mid-Atlantic States. Intense mid-level southerlies will become asymmetrically confined ahead of the trough by early morning Monday. Surface cyclogenesis will occur from the central/southern Appalachians across the Northeast into southern New England, with greater deepening during the latter half of the period. ...FL Panhandle to the Delmarva... Overall scenario appears similar to prior days with a broad swath of low-probability tornado and severe thunderstorm wind evident from Sunday morning to evening across the Southeast States. A mesoscale corridor of greater tornado/wind threat may be highlighted in later outlooks, seemingly within the eastern SC to southeast VA vicinity. A swath of showers and embedded thunderstorms will likely be ongoing 12Z Sunday from western/central VA to the FL Panhandle, within the warm conveyor ahead of a surface cold front steadily progressing eastward. Morning severe potential should generally be confined to the FL/GA portion of the risk area, where mid 60s surface dew points should be more common ahead of the early-day convection. Diurnal diabatic heating is still expected to be muted, with extensive low-level moistening and resultant cloudiness anticipated. Consensus of guidance still suggests that a separate low-level warm theta-e advection regime from the western Atlantic will aid in a secondary swath of convective development by late morning into the afternoon across the eastern Carolinas. A corridor of somewhat greater surface heating may occur between both regimes which could yield a mesoscale area of MLCAPE from 500-1000 J/kg. Otherwise, amid weak mid-level lapse rates, much of the region should hold with MLCAPE at or below 500 J/kg. Low-level hodographs will be more favorably enlarged from the Carolinas northward. Should this become coincident with greater than meager buoyancy, a level 2-SLGT risk may be warranted for Sunday afternoon. More prominent strengthening of low-level southerlies will occur on Sunday night as cyclogenesis intensifies. However, the thermodynamic environment may be mostly to completely overturned by this time frame, given widespread convection. Guidance varies substantially in whether scant to meager surface-based buoyancy can still linger ahead of the cold front, mainly across eastern NC. Should this occur, a brief tornado/damaging-wind threat may be sustained through late evening. ..Grams.. 12/09/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1243 AM CST Sat Dec 09 2023 Valid 101200Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FL PANHANDLE TO THE DELMARVA... ...SUMMARY... Isolated severe thunderstorms will be possible through Sunday evening across parts of the Southeast States, mainly in the form of sporadic damaging winds and a few brief tornadoes. ...Synopsis... An amplified, positive-tilt upper trough from ON to east TX at 12Z Sunday will take on a neutral to slight negative tilt as a basal shortwave impulse rapidly ejects across the Deep South to the Lower Mid-Atlantic States. Intense mid-level southerlies will become asymmetrically confined ahead of the trough by early morning Monday. Surface cyclogenesis will occur from the central/southern Appalachians across the Northeast into southern New England, with greater deepening during the latter half of the period. ...FL Panhandle to the Delmarva... Overall scenario appears similar to prior days with a broad swath of low-probability tornado and severe thunderstorm wind evident from Sunday morning to evening across the Southeast States. A mesoscale corridor of greater tornado/wind threat may be highlighted in later outlooks, seemingly within the eastern SC to southeast VA vicinity. A swath of showers and embedded thunderstorms will likely be ongoing 12Z Sunday from western/central VA to the FL Panhandle, within the warm conveyor ahead of a surface cold front steadily progressing eastward. Morning severe potential should generally be confined to the FL/GA portion of the risk area, where mid 60s surface dew points should be more common ahead of the early-day convection. Diurnal diabatic heating is still expected to be muted, with extensive low-level moistening and resultant cloudiness anticipated. Consensus of guidance still suggests that a separate low-level warm theta-e advection regime from the western Atlantic will aid in a secondary swath of convective development by late morning into the afternoon across the eastern Carolinas. A corridor of somewhat greater surface heating may occur between both regimes which could yield a mesoscale area of MLCAPE from 500-1000 J/kg. Otherwise, amid weak mid-level lapse rates, much of the region should hold with MLCAPE at or below 500 J/kg. Low-level hodographs will be more favorably enlarged from the Carolinas northward. Should this become coincident with greater than meager buoyancy, a level 2-SLGT risk may be warranted for Sunday afternoon. More prominent strengthening of low-level southerlies will occur on Sunday night as cyclogenesis intensifies. However, the thermodynamic environment may be mostly to completely overturned by this time frame, given widespread convection. Guidance varies substantially in whether scant to meager surface-based buoyancy can still linger ahead of the cold front, mainly across eastern NC. Should this occur, a brief tornado/damaging-wind threat may be sustained through late evening. ..Grams.. 12/09/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1243 AM CST Sat Dec 09 2023 Valid 101200Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FL PANHANDLE TO THE DELMARVA... ...SUMMARY... Isolated severe thunderstorms will be possible through Sunday evening across parts of the Southeast States, mainly in the form of sporadic damaging winds and a few brief tornadoes. ...Synopsis... An amplified, positive-tilt upper trough from ON to east TX at 12Z Sunday will take on a neutral to slight negative tilt as a basal shortwave impulse rapidly ejects across the Deep South to the Lower Mid-Atlantic States. Intense mid-level southerlies will become asymmetrically confined ahead of the trough by early morning Monday. Surface cyclogenesis will occur from the central/southern Appalachians across the Northeast into southern New England, with greater deepening during the latter half of the period. ...FL Panhandle to the Delmarva... Overall scenario appears similar to prior days with a broad swath of low-probability tornado and severe thunderstorm wind evident from Sunday morning to evening across the Southeast States. A mesoscale corridor of greater tornado/wind threat may be highlighted in later outlooks, seemingly within the eastern SC to southeast VA vicinity. A swath of showers and embedded thunderstorms will likely be ongoing 12Z Sunday from western/central VA to the FL Panhandle, within the warm conveyor ahead of a surface cold front steadily progressing eastward. Morning severe potential should generally be confined to the FL/GA portion of the risk area, where mid 60s surface dew points should be more common ahead of the early-day convection. Diurnal diabatic heating is still expected to be muted, with extensive low-level moistening and resultant cloudiness anticipated. Consensus of guidance still suggests that a separate low-level warm theta-e advection regime from the western Atlantic will aid in a secondary swath of convective development by late morning into the afternoon across the eastern Carolinas. A corridor of somewhat greater surface heating may occur between both regimes which could yield a mesoscale area of MLCAPE from 500-1000 J/kg. Otherwise, amid weak mid-level lapse rates, much of the region should hold with MLCAPE at or below 500 J/kg. Low-level hodographs will be more favorably enlarged from the Carolinas northward. Should this become coincident with greater than meager buoyancy, a level 2-SLGT risk may be warranted for Sunday afternoon. More prominent strengthening of low-level southerlies will occur on Sunday night as cyclogenesis intensifies. However, the thermodynamic environment may be mostly to completely overturned by this time frame, given widespread convection. Guidance varies substantially in whether scant to meager surface-based buoyancy can still linger ahead of the cold front, mainly across eastern NC. Should this occur, a brief tornado/damaging-wind threat may be sustained through late evening. ..Grams.. 12/09/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1243 AM CST Sat Dec 09 2023 Valid 101200Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FL PANHANDLE TO THE DELMARVA... ...SUMMARY... Isolated severe thunderstorms will be possible through Sunday evening across parts of the Southeast States, mainly in the form of sporadic damaging winds and a few brief tornadoes. ...Synopsis... An amplified, positive-tilt upper trough from ON to east TX at 12Z Sunday will take on a neutral to slight negative tilt as a basal shortwave impulse rapidly ejects across the Deep South to the Lower Mid-Atlantic States. Intense mid-level southerlies will become asymmetrically confined ahead of the trough by early morning Monday. Surface cyclogenesis will occur from the central/southern Appalachians across the Northeast into southern New England, with greater deepening during the latter half of the period. ...FL Panhandle to the Delmarva... Overall scenario appears similar to prior days with a broad swath of low-probability tornado and severe thunderstorm wind evident from Sunday morning to evening across the Southeast States. A mesoscale corridor of greater tornado/wind threat may be highlighted in later outlooks, seemingly within the eastern SC to southeast VA vicinity. A swath of showers and embedded thunderstorms will likely be ongoing 12Z Sunday from western/central VA to the FL Panhandle, within the warm conveyor ahead of a surface cold front steadily progressing eastward. Morning severe potential should generally be confined to the FL/GA portion of the risk area, where mid 60s surface dew points should be more common ahead of the early-day convection. Diurnal diabatic heating is still expected to be muted, with extensive low-level moistening and resultant cloudiness anticipated. Consensus of guidance still suggests that a separate low-level warm theta-e advection regime from the western Atlantic will aid in a secondary swath of convective development by late morning into the afternoon across the eastern Carolinas. A corridor of somewhat greater surface heating may occur between both regimes which could yield a mesoscale area of MLCAPE from 500-1000 J/kg. Otherwise, amid weak mid-level lapse rates, much of the region should hold with MLCAPE at or below 500 J/kg. Low-level hodographs will be more favorably enlarged from the Carolinas northward. Should this become coincident with greater than meager buoyancy, a level 2-SLGT risk may be warranted for Sunday afternoon. More prominent strengthening of low-level southerlies will occur on Sunday night as cyclogenesis intensifies. However, the thermodynamic environment may be mostly to completely overturned by this time frame, given widespread convection. Guidance varies substantially in whether scant to meager surface-based buoyancy can still linger ahead of the cold front, mainly across eastern NC. Should this occur, a brief tornado/damaging-wind threat may be sustained through late evening. ..Grams.. 12/09/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1243 AM CST Sat Dec 09 2023 Valid 101200Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FL PANHANDLE TO THE DELMARVA... ...SUMMARY... Isolated severe thunderstorms will be possible through Sunday evening across parts of the Southeast States, mainly in the form of sporadic damaging winds and a few brief tornadoes. ...Synopsis... An amplified, positive-tilt upper trough from ON to east TX at 12Z Sunday will take on a neutral to slight negative tilt as a basal shortwave impulse rapidly ejects across the Deep South to the Lower Mid-Atlantic States. Intense mid-level southerlies will become asymmetrically confined ahead of the trough by early morning Monday. Surface cyclogenesis will occur from the central/southern Appalachians across the Northeast into southern New England, with greater deepening during the latter half of the period. ...FL Panhandle to the Delmarva... Overall scenario appears similar to prior days with a broad swath of low-probability tornado and severe thunderstorm wind evident from Sunday morning to evening across the Southeast States. A mesoscale corridor of greater tornado/wind threat may be highlighted in later outlooks, seemingly within the eastern SC to southeast VA vicinity. A swath of showers and embedded thunderstorms will likely be ongoing 12Z Sunday from western/central VA to the FL Panhandle, within the warm conveyor ahead of a surface cold front steadily progressing eastward. Morning severe potential should generally be confined to the FL/GA portion of the risk area, where mid 60s surface dew points should be more common ahead of the early-day convection. Diurnal diabatic heating is still expected to be muted, with extensive low-level moistening and resultant cloudiness anticipated. Consensus of guidance still suggests that a separate low-level warm theta-e advection regime from the western Atlantic will aid in a secondary swath of convective development by late morning into the afternoon across the eastern Carolinas. A corridor of somewhat greater surface heating may occur between both regimes which could yield a mesoscale area of MLCAPE from 500-1000 J/kg. Otherwise, amid weak mid-level lapse rates, much of the region should hold with MLCAPE at or below 500 J/kg. Low-level hodographs will be more favorably enlarged from the Carolinas northward. Should this become coincident with greater than meager buoyancy, a level 2-SLGT risk may be warranted for Sunday afternoon. More prominent strengthening of low-level southerlies will occur on Sunday night as cyclogenesis intensifies. However, the thermodynamic environment may be mostly to completely overturned by this time frame, given widespread convection. Guidance varies substantially in whether scant to meager surface-based buoyancy can still linger ahead of the cold front, mainly across eastern NC. Should this occur, a brief tornado/damaging-wind threat may be sustained through late evening. ..Grams.. 12/09/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1157 PM CST Fri Dec 08 2023 Valid 091200Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE LOWER TO MID MISSISSIPPI VALLEY NORTHEASTWARD INTO THE TENNESSEE VALLEY... ...SUMMARY... Severe thunderstorms, capable of producing a few tornadoes, scattered damaging winds, and large hail, will be possible from the lower Mississippi Valley northeastward into the Tennessee Valley this afternoon and evening. Marginally severe storms could also develop in parts of the Ohio Valley and in the central Gulf Coast region. ...Lower Mississippi Valley/Tennessee Valley/Ohio Valley... A positively-tilted mid-level trough and an associated belt of strong flow will move eastward into the mid Mississippi Valley today. At the surface, a cold front will advance southeastward into the mid Mississippi Valley as a moist air mass advects northward across the central Gulf Coast states and Tennessee Valley. Surface dewpoints are forecast to increase into the 60s F across northern Mississippi, northern Alabama and in the western half of Tennessee. During the day, elevated thunderstorms appear likely to develop on the northern edge of the moist air mass, with a cluster of storms moving east-northeastward across northern Arkansas and western Tennessee. This cluster may be associated with a marginal threat for hail and wind damage. To the south of this cluster, the airmass should become moderately unstable by early afternoon, with MLCAPE peaking in the 1500 to 1800 J/kg range, according to RAP forecast soundings. During the mid to late afternoon, thunderstorms are expected to initiate along and ahead of the front, with a gradual increase in storm coverage taking place across the region. The eastern edge of the mid-level jet will overspread the warm sector this afternoon, creating strong deep-layer shear favorable for severe storms. 0-6 km shear values are forecast to increase into the 50 to 60 knot range, suggesting supercells will be possible. Storm-relative helicity in the 200 to 300 m2/s2 range will support a tornado threat, especially with cells that remain discrete. Although a tornado threat is expected to develop over a broad area from far eastern Arkansas northeastward into middle Tennessee, the most focused tornado potential may be from northwest Alabama into southern Tennessee. In this area, the combination of low-level shear and instability is expected to become maximized during the late afternoon and early evening. In addition to supercells, multicell clusters and line segments will be likely. The stronger rotating storms and multicell line segments may be capable of damaging wind gusts. The large hail threat will likely be associated with the more widely scattered supercells that develop further west into parts of the lower Mississippi Valley, where mid-level lapse rates are forecast to be steeper. The severe threat over the Tennessee Valley should persist into the mid to late evening as a line segment gradually develops ahead of the cold front. Further north into the Ohio Valley, instability is forecast remain weak in the afternoon and evening with RAP forecast soundings having MLCAPE peak in the 500 to 800 J/kg range. In spite of this, 0-6 km shear from 60 to 70 knots will support an isolated severe threat. Any potential for tornadoes, wind damage and hail is expected to remain isolated and marginal. ..Broyles/Wendt.. 12/09/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1157 PM CST Fri Dec 08 2023 Valid 091200Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE LOWER TO MID MISSISSIPPI VALLEY NORTHEASTWARD INTO THE TENNESSEE VALLEY... ...SUMMARY... Severe thunderstorms, capable of producing a few tornadoes, scattered damaging winds, and large hail, will be possible from the lower Mississippi Valley northeastward into the Tennessee Valley this afternoon and evening. Marginally severe storms could also develop in parts of the Ohio Valley and in the central Gulf Coast region. ...Lower Mississippi Valley/Tennessee Valley/Ohio Valley... A positively-tilted mid-level trough and an associated belt of strong flow will move eastward into the mid Mississippi Valley today. At the surface, a cold front will advance southeastward into the mid Mississippi Valley as a moist air mass advects northward across the central Gulf Coast states and Tennessee Valley. Surface dewpoints are forecast to increase into the 60s F across northern Mississippi, northern Alabama and in the western half of Tennessee. During the day, elevated thunderstorms appear likely to develop on the northern edge of the moist air mass, with a cluster of storms moving east-northeastward across northern Arkansas and western Tennessee. This cluster may be associated with a marginal threat for hail and wind damage. To the south of this cluster, the airmass should become moderately unstable by early afternoon, with MLCAPE peaking in the 1500 to 1800 J/kg range, according to RAP forecast soundings. During the mid to late afternoon, thunderstorms are expected to initiate along and ahead of the front, with a gradual increase in storm coverage taking place across the region. The eastern edge of the mid-level jet will overspread the warm sector this afternoon, creating strong deep-layer shear favorable for severe storms. 0-6 km shear values are forecast to increase into the 50 to 60 knot range, suggesting supercells will be possible. Storm-relative helicity in the 200 to 300 m2/s2 range will support a tornado threat, especially with cells that remain discrete. Although a tornado threat is expected to develop over a broad area from far eastern Arkansas northeastward into middle Tennessee, the most focused tornado potential may be from northwest Alabama into southern Tennessee. In this area, the combination of low-level shear and instability is expected to become maximized during the late afternoon and early evening. In addition to supercells, multicell clusters and line segments will be likely. The stronger rotating storms and multicell line segments may be capable of damaging wind gusts. The large hail threat will likely be associated with the more widely scattered supercells that develop further west into parts of the lower Mississippi Valley, where mid-level lapse rates are forecast to be steeper. The severe threat over the Tennessee Valley should persist into the mid to late evening as a line segment gradually develops ahead of the cold front. Further north into the Ohio Valley, instability is forecast remain weak in the afternoon and evening with RAP forecast soundings having MLCAPE peak in the 500 to 800 J/kg range. In spite of this, 0-6 km shear from 60 to 70 knots will support an isolated severe threat. Any potential for tornadoes, wind damage and hail is expected to remain isolated and marginal. ..Broyles/Wendt.. 12/09/2023 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1157 PM CST Fri Dec 08 2023 Valid 091200Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE LOWER TO MID MISSISSIPPI VALLEY NORTHEASTWARD INTO THE TENNESSEE VALLEY... ...SUMMARY... Severe thunderstorms, capable of producing a few tornadoes, scattered damaging winds, and large hail, will be possible from the lower Mississippi Valley northeastward into the Tennessee Valley this afternoon and evening. Marginally severe storms could also develop in parts of the Ohio Valley and in the central Gulf Coast region. ...Lower Mississippi Valley/Tennessee Valley/Ohio Valley... A positively-tilted mid-level trough and an associated belt of strong flow will move eastward into the mid Mississippi Valley today. At the surface, a cold front will advance southeastward into the mid Mississippi Valley as a moist air mass advects northward across the central Gulf Coast states and Tennessee Valley. Surface dewpoints are forecast to increase into the 60s F across northern Mississippi, northern Alabama and in the western half of Tennessee. During the day, elevated thunderstorms appear likely to develop on the northern edge of the moist air mass, with a cluster of storms moving east-northeastward across northern Arkansas and western Tennessee. This cluster may be associated with a marginal threat for hail and wind damage. To the south of this cluster, the airmass should become moderately unstable by early afternoon, with MLCAPE peaking in the 1500 to 1800 J/kg range, according to RAP forecast soundings. During the mid to late afternoon, thunderstorms are expected to initiate along and ahead of the front, with a gradual increase in storm coverage taking place across the region. The eastern edge of the mid-level jet will overspread the warm sector this afternoon, creating strong deep-layer shear favorable for severe storms. 0-6 km shear values are forecast to increase into the 50 to 60 knot range, suggesting supercells will be possible. Storm-relative helicity in the 200 to 300 m2/s2 range will support a tornado threat, especially with cells that remain discrete. Although a tornado threat is expected to develop over a broad area from far eastern Arkansas northeastward into middle Tennessee, the most focused tornado potential may be from northwest Alabama into southern Tennessee. In this area, the combination of low-level shear and instability is expected to become maximized during the late afternoon and early evening. In addition to supercells, multicell clusters and line segments will be likely. The stronger rotating storms and multicell line segments may be capable of damaging wind gusts. The large hail threat will likely be associated with the more widely scattered supercells that develop further west into parts of the lower Mississippi Valley, where mid-level lapse rates are forecast to be steeper. The severe threat over the Tennessee Valley should persist into the mid to late evening as a line segment gradually develops ahead of the cold front. Further north into the Ohio Valley, instability is forecast remain weak in the afternoon and evening with RAP forecast soundings having MLCAPE peak in the 500 to 800 J/kg range. In spite of this, 0-6 km shear from 60 to 70 knots will support an isolated severe threat. Any potential for tornadoes, wind damage and hail is expected to remain isolated and marginal. ..Broyles/Wendt.. 12/09/2023 Read more