Severe Storms

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0600 AM CST Thu Dec 14 2023 Valid 141300Z - 151200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis... A midlevel closed low over AZ will continue eastward across NM to the TX Panhandle by early Friday. Primarily elevated thunderstorms will continue to be possible periodically from eastern NM into northwest TX/western OK where 200-400 J/kg MUCAPE rooted aloft will coincide with warm advection and differential cyclonic vorticity advection east of the midlevel low. Farther south and east, an easterly low-level flow regime will persist along a remnant front from the FL Straits to the western Gulf of Mexico. Thermodynamic profiles will be somewhat marginal for charge separation across Deep South TX and near the Keys/southeast FL coast within the northwest edge of a largely modified air mass and convergent low-level flow near the coast, though isolated flashes will be possible. ..Thompson/Gleason.. 12/14/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0600 AM CST Thu Dec 14 2023 Valid 141300Z - 151200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis... A midlevel closed low over AZ will continue eastward across NM to the TX Panhandle by early Friday. Primarily elevated thunderstorms will continue to be possible periodically from eastern NM into northwest TX/western OK where 200-400 J/kg MUCAPE rooted aloft will coincide with warm advection and differential cyclonic vorticity advection east of the midlevel low. Farther south and east, an easterly low-level flow regime will persist along a remnant front from the FL Straits to the western Gulf of Mexico. Thermodynamic profiles will be somewhat marginal for charge separation across Deep South TX and near the Keys/southeast FL coast within the northwest edge of a largely modified air mass and convergent low-level flow near the coast, though isolated flashes will be possible. ..Thompson/Gleason.. 12/14/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0600 AM CST Thu Dec 14 2023 Valid 141300Z - 151200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis... A midlevel closed low over AZ will continue eastward across NM to the TX Panhandle by early Friday. Primarily elevated thunderstorms will continue to be possible periodically from eastern NM into northwest TX/western OK where 200-400 J/kg MUCAPE rooted aloft will coincide with warm advection and differential cyclonic vorticity advection east of the midlevel low. Farther south and east, an easterly low-level flow regime will persist along a remnant front from the FL Straits to the western Gulf of Mexico. Thermodynamic profiles will be somewhat marginal for charge separation across Deep South TX and near the Keys/southeast FL coast within the northwest edge of a largely modified air mass and convergent low-level flow near the coast, though isolated flashes will be possible. ..Thompson/Gleason.. 12/14/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0600 AM CST Thu Dec 14 2023 Valid 141300Z - 151200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis... A midlevel closed low over AZ will continue eastward across NM to the TX Panhandle by early Friday. Primarily elevated thunderstorms will continue to be possible periodically from eastern NM into northwest TX/western OK where 200-400 J/kg MUCAPE rooted aloft will coincide with warm advection and differential cyclonic vorticity advection east of the midlevel low. Farther south and east, an easterly low-level flow regime will persist along a remnant front from the FL Straits to the western Gulf of Mexico. Thermodynamic profiles will be somewhat marginal for charge separation across Deep South TX and near the Keys/southeast FL coast within the northwest edge of a largely modified air mass and convergent low-level flow near the coast, though isolated flashes will be possible. ..Thompson/Gleason.. 12/14/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0600 AM CST Thu Dec 14 2023 Valid 141300Z - 151200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis... A midlevel closed low over AZ will continue eastward across NM to the TX Panhandle by early Friday. Primarily elevated thunderstorms will continue to be possible periodically from eastern NM into northwest TX/western OK where 200-400 J/kg MUCAPE rooted aloft will coincide with warm advection and differential cyclonic vorticity advection east of the midlevel low. Farther south and east, an easterly low-level flow regime will persist along a remnant front from the FL Straits to the western Gulf of Mexico. Thermodynamic profiles will be somewhat marginal for charge separation across Deep South TX and near the Keys/southeast FL coast within the northwest edge of a largely modified air mass and convergent low-level flow near the coast, though isolated flashes will be possible. ..Thompson/Gleason.. 12/14/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0600 AM CST Thu Dec 14 2023 Valid 141300Z - 151200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis... A midlevel closed low over AZ will continue eastward across NM to the TX Panhandle by early Friday. Primarily elevated thunderstorms will continue to be possible periodically from eastern NM into northwest TX/western OK where 200-400 J/kg MUCAPE rooted aloft will coincide with warm advection and differential cyclonic vorticity advection east of the midlevel low. Farther south and east, an easterly low-level flow regime will persist along a remnant front from the FL Straits to the western Gulf of Mexico. Thermodynamic profiles will be somewhat marginal for charge separation across Deep South TX and near the Keys/southeast FL coast within the northwest edge of a largely modified air mass and convergent low-level flow near the coast, though isolated flashes will be possible. ..Thompson/Gleason.. 12/14/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0600 AM CST Thu Dec 14 2023 Valid 141300Z - 151200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis... A midlevel closed low over AZ will continue eastward across NM to the TX Panhandle by early Friday. Primarily elevated thunderstorms will continue to be possible periodically from eastern NM into northwest TX/western OK where 200-400 J/kg MUCAPE rooted aloft will coincide with warm advection and differential cyclonic vorticity advection east of the midlevel low. Farther south and east, an easterly low-level flow regime will persist along a remnant front from the FL Straits to the western Gulf of Mexico. Thermodynamic profiles will be somewhat marginal for charge separation across Deep South TX and near the Keys/southeast FL coast within the northwest edge of a largely modified air mass and convergent low-level flow near the coast, though isolated flashes will be possible. ..Thompson/Gleason.. 12/14/2023 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CST Thu Dec 14 2023 Valid 171200Z - 221200Z ...DISCUSSION... An area-of-interest for at least low probability tornado and damaging wind potential continues on D4, centered on parts of FL to the eastern Carolinas. Overall consensus continues the trend for further cyclogenesis on D4 with potential phasing of three northern and southern stream impulses into an amplified shortwave trough over the Southeast. This may further interact with an amplifying shortwave trough digging from the Canadian Prairies across the Upper Midwest to OH Valley late D4 to D5. The large spread in ensemble and deterministic guidance with cyclone timing and track from the eastern Gulf to South Atlantic Coast vicinity on D3, continues into D4-5. Latest trends have been for a faster and more westward inland track across the East, versus prior days indicating more of an offshore track. This would seemingly support a conditionally favorable high-shear/low-CAPE warm sector shifting from the FL Peninsula across at least the eastern Carolinas, before the warm sector occludes over land. The timing of this shift is rather uncertain. Slower, but increasingly minority guidance suggest some severe threat could linger over the FL Peninsula early Sunday, before shifting into the Carolinas later Sunday. Faster guidance suggest the FL threat should become nil after 12Z Sunday and favor the eastern Carolinas during the first half of D4. ...D5-8... While intense low-level wind fields may linger into early D5/Monday over parts of the Mid-Atlantic and Northeast States, faster guidance trends suggest potential is slim for this to be coincident with appreciable surface-based instability. Beyond that time frame, severe potential appears negligible across the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CST Thu Dec 14 2023 Valid 171200Z - 221200Z ...DISCUSSION... An area-of-interest for at least low probability tornado and damaging wind potential continues on D4, centered on parts of FL to the eastern Carolinas. Overall consensus continues the trend for further cyclogenesis on D4 with potential phasing of three northern and southern stream impulses into an amplified shortwave trough over the Southeast. This may further interact with an amplifying shortwave trough digging from the Canadian Prairies across the Upper Midwest to OH Valley late D4 to D5. The large spread in ensemble and deterministic guidance with cyclone timing and track from the eastern Gulf to South Atlantic Coast vicinity on D3, continues into D4-5. Latest trends have been for a faster and more westward inland track across the East, versus prior days indicating more of an offshore track. This would seemingly support a conditionally favorable high-shear/low-CAPE warm sector shifting from the FL Peninsula across at least the eastern Carolinas, before the warm sector occludes over land. The timing of this shift is rather uncertain. Slower, but increasingly minority guidance suggest some severe threat could linger over the FL Peninsula early Sunday, before shifting into the Carolinas later Sunday. Faster guidance suggest the FL threat should become nil after 12Z Sunday and favor the eastern Carolinas during the first half of D4. ...D5-8... While intense low-level wind fields may linger into early D5/Monday over parts of the Mid-Atlantic and Northeast States, faster guidance trends suggest potential is slim for this to be coincident with appreciable surface-based instability. Beyond that time frame, severe potential appears negligible across the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CST Thu Dec 14 2023 Valid 171200Z - 221200Z ...DISCUSSION... An area-of-interest for at least low probability tornado and damaging wind potential continues on D4, centered on parts of FL to the eastern Carolinas. Overall consensus continues the trend for further cyclogenesis on D4 with potential phasing of three northern and southern stream impulses into an amplified shortwave trough over the Southeast. This may further interact with an amplifying shortwave trough digging from the Canadian Prairies across the Upper Midwest to OH Valley late D4 to D5. The large spread in ensemble and deterministic guidance with cyclone timing and track from the eastern Gulf to South Atlantic Coast vicinity on D3, continues into D4-5. Latest trends have been for a faster and more westward inland track across the East, versus prior days indicating more of an offshore track. This would seemingly support a conditionally favorable high-shear/low-CAPE warm sector shifting from the FL Peninsula across at least the eastern Carolinas, before the warm sector occludes over land. The timing of this shift is rather uncertain. Slower, but increasingly minority guidance suggest some severe threat could linger over the FL Peninsula early Sunday, before shifting into the Carolinas later Sunday. Faster guidance suggest the FL threat should become nil after 12Z Sunday and favor the eastern Carolinas during the first half of D4. ...D5-8... While intense low-level wind fields may linger into early D5/Monday over parts of the Mid-Atlantic and Northeast States, faster guidance trends suggest potential is slim for this to be coincident with appreciable surface-based instability. Beyond that time frame, severe potential appears negligible across the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CST Thu Dec 14 2023 Valid 171200Z - 221200Z ...DISCUSSION... An area-of-interest for at least low probability tornado and damaging wind potential continues on D4, centered on parts of FL to the eastern Carolinas. Overall consensus continues the trend for further cyclogenesis on D4 with potential phasing of three northern and southern stream impulses into an amplified shortwave trough over the Southeast. This may further interact with an amplifying shortwave trough digging from the Canadian Prairies across the Upper Midwest to OH Valley late D4 to D5. The large spread in ensemble and deterministic guidance with cyclone timing and track from the eastern Gulf to South Atlantic Coast vicinity on D3, continues into D4-5. Latest trends have been for a faster and more westward inland track across the East, versus prior days indicating more of an offshore track. This would seemingly support a conditionally favorable high-shear/low-CAPE warm sector shifting from the FL Peninsula across at least the eastern Carolinas, before the warm sector occludes over land. The timing of this shift is rather uncertain. Slower, but increasingly minority guidance suggest some severe threat could linger over the FL Peninsula early Sunday, before shifting into the Carolinas later Sunday. Faster guidance suggest the FL threat should become nil after 12Z Sunday and favor the eastern Carolinas during the first half of D4. ...D5-8... While intense low-level wind fields may linger into early D5/Monday over parts of the Mid-Atlantic and Northeast States, faster guidance trends suggest potential is slim for this to be coincident with appreciable surface-based instability. Beyond that time frame, severe potential appears negligible across the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CST Thu Dec 14 2023 Valid 171200Z - 221200Z ...DISCUSSION... An area-of-interest for at least low probability tornado and damaging wind potential continues on D4, centered on parts of FL to the eastern Carolinas. Overall consensus continues the trend for further cyclogenesis on D4 with potential phasing of three northern and southern stream impulses into an amplified shortwave trough over the Southeast. This may further interact with an amplifying shortwave trough digging from the Canadian Prairies across the Upper Midwest to OH Valley late D4 to D5. The large spread in ensemble and deterministic guidance with cyclone timing and track from the eastern Gulf to South Atlantic Coast vicinity on D3, continues into D4-5. Latest trends have been for a faster and more westward inland track across the East, versus prior days indicating more of an offshore track. This would seemingly support a conditionally favorable high-shear/low-CAPE warm sector shifting from the FL Peninsula across at least the eastern Carolinas, before the warm sector occludes over land. The timing of this shift is rather uncertain. Slower, but increasingly minority guidance suggest some severe threat could linger over the FL Peninsula early Sunday, before shifting into the Carolinas later Sunday. Faster guidance suggest the FL threat should become nil after 12Z Sunday and favor the eastern Carolinas during the first half of D4. ...D5-8... While intense low-level wind fields may linger into early D5/Monday over parts of the Mid-Atlantic and Northeast States, faster guidance trends suggest potential is slim for this to be coincident with appreciable surface-based instability. Beyond that time frame, severe potential appears negligible across the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CST Thu Dec 14 2023 Valid 171200Z - 221200Z ...DISCUSSION... An area-of-interest for at least low probability tornado and damaging wind potential continues on D4, centered on parts of FL to the eastern Carolinas. Overall consensus continues the trend for further cyclogenesis on D4 with potential phasing of three northern and southern stream impulses into an amplified shortwave trough over the Southeast. This may further interact with an amplifying shortwave trough digging from the Canadian Prairies across the Upper Midwest to OH Valley late D4 to D5. The large spread in ensemble and deterministic guidance with cyclone timing and track from the eastern Gulf to South Atlantic Coast vicinity on D3, continues into D4-5. Latest trends have been for a faster and more westward inland track across the East, versus prior days indicating more of an offshore track. This would seemingly support a conditionally favorable high-shear/low-CAPE warm sector shifting from the FL Peninsula across at least the eastern Carolinas, before the warm sector occludes over land. The timing of this shift is rather uncertain. Slower, but increasingly minority guidance suggest some severe threat could linger over the FL Peninsula early Sunday, before shifting into the Carolinas later Sunday. Faster guidance suggest the FL threat should become nil after 12Z Sunday and favor the eastern Carolinas during the first half of D4. ...D5-8... While intense low-level wind fields may linger into early D5/Monday over parts of the Mid-Atlantic and Northeast States, faster guidance trends suggest potential is slim for this to be coincident with appreciable surface-based instability. Beyond that time frame, severe potential appears negligible across the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CST Thu Dec 14 2023 Valid 171200Z - 221200Z ...DISCUSSION... An area-of-interest for at least low probability tornado and damaging wind potential continues on D4, centered on parts of FL to the eastern Carolinas. Overall consensus continues the trend for further cyclogenesis on D4 with potential phasing of three northern and southern stream impulses into an amplified shortwave trough over the Southeast. This may further interact with an amplifying shortwave trough digging from the Canadian Prairies across the Upper Midwest to OH Valley late D4 to D5. The large spread in ensemble and deterministic guidance with cyclone timing and track from the eastern Gulf to South Atlantic Coast vicinity on D3, continues into D4-5. Latest trends have been for a faster and more westward inland track across the East, versus prior days indicating more of an offshore track. This would seemingly support a conditionally favorable high-shear/low-CAPE warm sector shifting from the FL Peninsula across at least the eastern Carolinas, before the warm sector occludes over land. The timing of this shift is rather uncertain. Slower, but increasingly minority guidance suggest some severe threat could linger over the FL Peninsula early Sunday, before shifting into the Carolinas later Sunday. Faster guidance suggest the FL threat should become nil after 12Z Sunday and favor the eastern Carolinas during the first half of D4. ...D5-8... While intense low-level wind fields may linger into early D5/Monday over parts of the Mid-Atlantic and Northeast States, faster guidance trends suggest potential is slim for this to be coincident with appreciable surface-based instability. Beyond that time frame, severe potential appears negligible across the CONUS. Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 AM CST Thu Dec 14 2023 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE FL PENINSULA... ...SUMMARY... A low confidence forecast exists for Saturday evening/night, but nocturnal tornado potential remains apparent across the Florida Peninsula. ...FL vicinity... A complex synoptic pattern with much greater-than-normal spread exists across the suite of ensemble and deterministic guidance. The degree of phasing between southern and northern-stream shortwave troughs over the central states is quite varied. Uncertainty also exists with how these features interact with a separate, yet to form, shortwave impulse generated by abundant convection over the eastern Gulf late D2/early D3, within a favorable right-rear quadrant of an intensifying upper jet centered on the Deep South. It is this latter feature which would likely induce cyclogenesis over the eastern Gulf vicinity. 00Z ECMWF ensemble members continue to indicate large spread in the degree of cyclone amplification and track prior to 12Z Sunday. Non-NCEP guidance such as the deterministic 00Z ECMWF, UKMET, and CMC are closer to the 00Z ECMWF ensemble mean and provide the primary basis for the areal delineation of the level 1-MRGL risk for Saturday evening/night. The initial warm-core nature of the leading impulse suggests poor mid-level lapse rates will require sufficient surface-based instability coincident with the expected strengthening low-level wind fields across the FL Peninsula. If the bulk of guidance eventually converges to the faster/more amplified cyclone track, a corridor of level 2-SLGT risk would seemingly be needed given the conditional high-shear/low-CAPE setup supporting potential for nocturnal tornadoes. ..Grams.. 12/14/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 AM CST Thu Dec 14 2023 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE FL PENINSULA... ...SUMMARY... A low confidence forecast exists for Saturday evening/night, but nocturnal tornado potential remains apparent across the Florida Peninsula. ...FL vicinity... A complex synoptic pattern with much greater-than-normal spread exists across the suite of ensemble and deterministic guidance. The degree of phasing between southern and northern-stream shortwave troughs over the central states is quite varied. Uncertainty also exists with how these features interact with a separate, yet to form, shortwave impulse generated by abundant convection over the eastern Gulf late D2/early D3, within a favorable right-rear quadrant of an intensifying upper jet centered on the Deep South. It is this latter feature which would likely induce cyclogenesis over the eastern Gulf vicinity. 00Z ECMWF ensemble members continue to indicate large spread in the degree of cyclone amplification and track prior to 12Z Sunday. Non-NCEP guidance such as the deterministic 00Z ECMWF, UKMET, and CMC are closer to the 00Z ECMWF ensemble mean and provide the primary basis for the areal delineation of the level 1-MRGL risk for Saturday evening/night. The initial warm-core nature of the leading impulse suggests poor mid-level lapse rates will require sufficient surface-based instability coincident with the expected strengthening low-level wind fields across the FL Peninsula. If the bulk of guidance eventually converges to the faster/more amplified cyclone track, a corridor of level 2-SLGT risk would seemingly be needed given the conditional high-shear/low-CAPE setup supporting potential for nocturnal tornadoes. ..Grams.. 12/14/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 AM CST Thu Dec 14 2023 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE FL PENINSULA... ...SUMMARY... A low confidence forecast exists for Saturday evening/night, but nocturnal tornado potential remains apparent across the Florida Peninsula. ...FL vicinity... A complex synoptic pattern with much greater-than-normal spread exists across the suite of ensemble and deterministic guidance. The degree of phasing between southern and northern-stream shortwave troughs over the central states is quite varied. Uncertainty also exists with how these features interact with a separate, yet to form, shortwave impulse generated by abundant convection over the eastern Gulf late D2/early D3, within a favorable right-rear quadrant of an intensifying upper jet centered on the Deep South. It is this latter feature which would likely induce cyclogenesis over the eastern Gulf vicinity. 00Z ECMWF ensemble members continue to indicate large spread in the degree of cyclone amplification and track prior to 12Z Sunday. Non-NCEP guidance such as the deterministic 00Z ECMWF, UKMET, and CMC are closer to the 00Z ECMWF ensemble mean and provide the primary basis for the areal delineation of the level 1-MRGL risk for Saturday evening/night. The initial warm-core nature of the leading impulse suggests poor mid-level lapse rates will require sufficient surface-based instability coincident with the expected strengthening low-level wind fields across the FL Peninsula. If the bulk of guidance eventually converges to the faster/more amplified cyclone track, a corridor of level 2-SLGT risk would seemingly be needed given the conditional high-shear/low-CAPE setup supporting potential for nocturnal tornadoes. ..Grams.. 12/14/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 AM CST Thu Dec 14 2023 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE FL PENINSULA... ...SUMMARY... A low confidence forecast exists for Saturday evening/night, but nocturnal tornado potential remains apparent across the Florida Peninsula. ...FL vicinity... A complex synoptic pattern with much greater-than-normal spread exists across the suite of ensemble and deterministic guidance. The degree of phasing between southern and northern-stream shortwave troughs over the central states is quite varied. Uncertainty also exists with how these features interact with a separate, yet to form, shortwave impulse generated by abundant convection over the eastern Gulf late D2/early D3, within a favorable right-rear quadrant of an intensifying upper jet centered on the Deep South. It is this latter feature which would likely induce cyclogenesis over the eastern Gulf vicinity. 00Z ECMWF ensemble members continue to indicate large spread in the degree of cyclone amplification and track prior to 12Z Sunday. Non-NCEP guidance such as the deterministic 00Z ECMWF, UKMET, and CMC are closer to the 00Z ECMWF ensemble mean and provide the primary basis for the areal delineation of the level 1-MRGL risk for Saturday evening/night. The initial warm-core nature of the leading impulse suggests poor mid-level lapse rates will require sufficient surface-based instability coincident with the expected strengthening low-level wind fields across the FL Peninsula. If the bulk of guidance eventually converges to the faster/more amplified cyclone track, a corridor of level 2-SLGT risk would seemingly be needed given the conditional high-shear/low-CAPE setup supporting potential for nocturnal tornadoes. ..Grams.. 12/14/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 AM CST Thu Dec 14 2023 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE FL PENINSULA... ...SUMMARY... A low confidence forecast exists for Saturday evening/night, but nocturnal tornado potential remains apparent across the Florida Peninsula. ...FL vicinity... A complex synoptic pattern with much greater-than-normal spread exists across the suite of ensemble and deterministic guidance. The degree of phasing between southern and northern-stream shortwave troughs over the central states is quite varied. Uncertainty also exists with how these features interact with a separate, yet to form, shortwave impulse generated by abundant convection over the eastern Gulf late D2/early D3, within a favorable right-rear quadrant of an intensifying upper jet centered on the Deep South. It is this latter feature which would likely induce cyclogenesis over the eastern Gulf vicinity. 00Z ECMWF ensemble members continue to indicate large spread in the degree of cyclone amplification and track prior to 12Z Sunday. Non-NCEP guidance such as the deterministic 00Z ECMWF, UKMET, and CMC are closer to the 00Z ECMWF ensemble mean and provide the primary basis for the areal delineation of the level 1-MRGL risk for Saturday evening/night. The initial warm-core nature of the leading impulse suggests poor mid-level lapse rates will require sufficient surface-based instability coincident with the expected strengthening low-level wind fields across the FL Peninsula. If the bulk of guidance eventually converges to the faster/more amplified cyclone track, a corridor of level 2-SLGT risk would seemingly be needed given the conditional high-shear/low-CAPE setup supporting potential for nocturnal tornadoes. ..Grams.. 12/14/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 AM CST Thu Dec 14 2023 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE FL PENINSULA... ...SUMMARY... A low confidence forecast exists for Saturday evening/night, but nocturnal tornado potential remains apparent across the Florida Peninsula. ...FL vicinity... A complex synoptic pattern with much greater-than-normal spread exists across the suite of ensemble and deterministic guidance. The degree of phasing between southern and northern-stream shortwave troughs over the central states is quite varied. Uncertainty also exists with how these features interact with a separate, yet to form, shortwave impulse generated by abundant convection over the eastern Gulf late D2/early D3, within a favorable right-rear quadrant of an intensifying upper jet centered on the Deep South. It is this latter feature which would likely induce cyclogenesis over the eastern Gulf vicinity. 00Z ECMWF ensemble members continue to indicate large spread in the degree of cyclone amplification and track prior to 12Z Sunday. Non-NCEP guidance such as the deterministic 00Z ECMWF, UKMET, and CMC are closer to the 00Z ECMWF ensemble mean and provide the primary basis for the areal delineation of the level 1-MRGL risk for Saturday evening/night. The initial warm-core nature of the leading impulse suggests poor mid-level lapse rates will require sufficient surface-based instability coincident with the expected strengthening low-level wind fields across the FL Peninsula. If the bulk of guidance eventually converges to the faster/more amplified cyclone track, a corridor of level 2-SLGT risk would seemingly be needed given the conditional high-shear/low-CAPE setup supporting potential for nocturnal tornadoes. ..Grams.. 12/14/2023 Read more