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SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1019 AM CST Tue Dec 10 2024 Valid 101630Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THROUGH THIS EVENING FROM CENTRAL ALABAMA INTO WEST-CENTRAL GEORGIA... ...SUMMARY... A few strong to severe thunderstorms may affect portions of central Alabama into west-central Georgia through this evening. ...AL/GA... The subtropical jet extends across the Gulf Coast region today, with several subtle shortwave troughs suggested in water vapor imagery that will affect parts of FL/AL/GA. Ample low-level moisture is present across central/southern AL/GA with dewpoints in the mid-upper 60s - yielding MUCAPE around 500 J/kg. Several 12z CAM solutions indicate a mesoscale low-level jet max that will intensify ahead of the cluster of showers/thunderstorms over west-central AL. This will lead to enhanced low-level vertical shear and forcing, providing support for a few supercell/bowing storm structures and the risk of a tornado or two and damaging wind gusts. Given these trends, have opted to upgrade this corridor to SLGT. Refer to MCD #2256 for further short-term details. ...Carolinas... Late tonight, the rapidly amplifying upper jet over the TN valley will lead to an organizing band of showers and low-topped thunderstorms along the cold front over SC/NC. It still looks like the main intensification of this line will occur after 12z, so will not expand the MRGL risk farther east. However, this area will continue to be re-evaluated in later outlooks. ..Hart/Squitieri.. 12/10/2024 Read more

MD 2255 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF EASTERN LOUISIANA INTO SOUTHERN MISSISSIPPI AND SOUTHWEST ALABAMA
Mesoscale Discussion 2255 NWS Storm Prediction Center Norman OK 0534 AM CST Tue Dec 10 2024 Areas affected...parts of eastern Louisiana into southern Mississippi and southwest Alabama Concerning...Severe potential...Watch unlikely Valid 101134Z - 101400Z Probability of Watch Issuance...20 percent SUMMARY...A brief/weak tornado or locally damaging gust may occur during the next several hours. Coverage of severe is not expected to warrant a watch. DISCUSSION...A slow-moving cold front currently extends from southwest LA into central and northeast MS, with generally weak surface winds. However, storms have increased in coverage near and just ahead of the boundary within the moistening air mass. Surface analysis shows dewpoints in the upper 60s F to near 70 F, along with 1-1.5 mb 2-hr pressure falls into southwest MS. Winds around 850 mb are around 30 kt out of the southwest, with 0-1 km SRH across the warm sector generally from 100 to 150 m2/s2. MUCAPE per objective analysis is generally in the 500-1000 J/kg range. In aggregate, the marginal instability, shear, and ascent may remain sufficient for a low risk of a brief tornado or locally damaging gusts over the next few hours as storms develop east/northeast across MS and into western AL. Instability may not be strong enough to support very long-lived supercells, but a QLCS-type tornado may occur in association with the stronger outflows. ..Jewell.. 12/10/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BMX...MOB...JAN...LIX... LAT...LON 30309133 31769032 32218966 32708834 32628768 32248746 31898755 31128830 30319065 30239105 30309133 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0639 AM CST Tue Dec 10 2024 Valid 101300Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF THE CENTRAL GULF COAST REGION INTO CENTRAL/SOUTHERN GEORGIA AND THE FLORIDA PANHANDLE... ...SUMMARY... A few strong to severe thunderstorms are possible across portions of the central Gulf Coast region into central/southern Georgia and the Florida Panhandle through tonight. ...Synopsis... In mid/upper levels, mean troughing over the central CONUS will evolve from positively to near neutrally tilted through the period, in conjunction with two predominant subsynoptic-scale processes: 1. South-southeastward digging of a cyclone now over extreme northern MB, reaching the MB/ON border east of Lake Winnipeg by 12Z tomorrow; 2. Eastward shift of a strong, basal shortwave trough -- now evident in moisture-channel imagery over northern NM into south-central AZ -- absorbing a weaker/trailing perturbation and reaching from middle TN to central LA by the end of the period. As this occurs, a surface cold front -- analyzed at 11Z from a low near BNA southwestward across northwestern MS, central LA, middle TX Coast, and deep south TX -- should extend from western PA across the southern Appalachians and southwestern AL, to southeastern LA, by 00Z. A low-level, prefrontal confluence/convergence zone may intensify this evening and tonight over portions of the FL Panhandle, southeastern AL and southwestern GA. The cold front should approach and perhaps overtake the confluence zone by 12Z, as it reaches a position from central PA across the western Carolinas, to near a MCN-AAF line, then over the northeastern/central Gulf. ...Southeast... Widely scattered, ongoing thunderstorms clusters are apparent across portions of southern MS into southeastern LA, with a marginal potential for a brief tornado or strong-severe gust. See SPC mesoscale discussion 2255 for near-term coverage of this scenario. Similarly sporadic, isolated and marginal tornado and severe-gust potential will exist throughout today and tonight with convection along and just ahead of the cold front, as well as slowly increasing convective coverage from late afternoon through overnight in the prefrontal convergence zone. The warm-sector environment will remain characterized by a nearly saturated boundary layer with surface dewpoints commonly in the upper 60s to near 70 F along the coast, to mid 60s well inland, amidst nearly moist-adiabatic low-level lapse rates. Somewhat greater boundary-layer instability is possible this afternoon in the inflow to the near-frontal convection, as modest heating occurs through cloud breaks. That my offset weak midlevel lapse rates enough to support peak MLCAPE around 1000 J/kg from southeastern LA to south-central AL, decreasing northeastward as well as eastward. An axis of lesser buoyancy -- with MLCAPE remaining in the 500-800 J/kg range, should shift eastward tonight near the confluence line, in support of convection there. Deep shear should increase from late this afternoon through tonight with the more neutral tilt of the larger-scale trough aloft, and related tightening of the mid/upper height gradient over the warm sector. While strongest flow aloft will remain behind the front, effective-shear magnitudes of 45-55 kt and elongated low-level hodographs are forecast from the northeastern Gulf Coast to the Carolinas. As the basal shortwave trough approaches (but remains behind the cold front), the LLJ should strengthen to 45-55 kt tonight over southern GA, reaching 55-65 kt over eastern NC, with lengthening but only somewhat curved low-level hodographs. The northeastward extent of the conditional severe potential may extend into near-coastal SC/NC; however, poor low- and middle-level lapse rates (with stable layers apparent in forecast soundings) are precluding any expansion of unconditional probabilities northeastward for this outlook cycle. The main (yet marginal) severe threat for the Carolinas still appears to hold off until early day 2. ..Edwards/Jewell.. 12/10/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0639 AM CST Tue Dec 10 2024 Valid 101300Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF THE CENTRAL GULF COAST REGION INTO CENTRAL/SOUTHERN GEORGIA AND THE FLORIDA PANHANDLE... ...SUMMARY... A few strong to severe thunderstorms are possible across portions of the central Gulf Coast region into central/southern Georgia and the Florida Panhandle through tonight. ...Synopsis... In mid/upper levels, mean troughing over the central CONUS will evolve from positively to near neutrally tilted through the period, in conjunction with two predominant subsynoptic-scale processes: 1. South-southeastward digging of a cyclone now over extreme northern MB, reaching the MB/ON border east of Lake Winnipeg by 12Z tomorrow; 2. Eastward shift of a strong, basal shortwave trough -- now evident in moisture-channel imagery over northern NM into south-central AZ -- absorbing a weaker/trailing perturbation and reaching from middle TN to central LA by the end of the period. As this occurs, a surface cold front -- analyzed at 11Z from a low near BNA southwestward across northwestern MS, central LA, middle TX Coast, and deep south TX -- should extend from western PA across the southern Appalachians and southwestern AL, to southeastern LA, by 00Z. A low-level, prefrontal confluence/convergence zone may intensify this evening and tonight over portions of the FL Panhandle, southeastern AL and southwestern GA. The cold front should approach and perhaps overtake the confluence zone by 12Z, as it reaches a position from central PA across the western Carolinas, to near a MCN-AAF line, then over the northeastern/central Gulf. ...Southeast... Widely scattered, ongoing thunderstorms clusters are apparent across portions of southern MS into southeastern LA, with a marginal potential for a brief tornado or strong-severe gust. See SPC mesoscale discussion 2255 for near-term coverage of this scenario. Similarly sporadic, isolated and marginal tornado and severe-gust potential will exist throughout today and tonight with convection along and just ahead of the cold front, as well as slowly increasing convective coverage from late afternoon through overnight in the prefrontal convergence zone. The warm-sector environment will remain characterized by a nearly saturated boundary layer with surface dewpoints commonly in the upper 60s to near 70 F along the coast, to mid 60s well inland, amidst nearly moist-adiabatic low-level lapse rates. Somewhat greater boundary-layer instability is possible this afternoon in the inflow to the near-frontal convection, as modest heating occurs through cloud breaks. That my offset weak midlevel lapse rates enough to support peak MLCAPE around 1000 J/kg from southeastern LA to south-central AL, decreasing northeastward as well as eastward. An axis of lesser buoyancy -- with MLCAPE remaining in the 500-800 J/kg range, should shift eastward tonight near the confluence line, in support of convection there. Deep shear should increase from late this afternoon through tonight with the more neutral tilt of the larger-scale trough aloft, and related tightening of the mid/upper height gradient over the warm sector. While strongest flow aloft will remain behind the front, effective-shear magnitudes of 45-55 kt and elongated low-level hodographs are forecast from the northeastern Gulf Coast to the Carolinas. As the basal shortwave trough approaches (but remains behind the cold front), the LLJ should strengthen to 45-55 kt tonight over southern GA, reaching 55-65 kt over eastern NC, with lengthening but only somewhat curved low-level hodographs. The northeastward extent of the conditional severe potential may extend into near-coastal SC/NC; however, poor low- and middle-level lapse rates (with stable layers apparent in forecast soundings) are precluding any expansion of unconditional probabilities northeastward for this outlook cycle. The main (yet marginal) severe threat for the Carolinas still appears to hold off until early day 2. ..Edwards/Jewell.. 12/10/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0639 AM CST Tue Dec 10 2024 Valid 101300Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF THE CENTRAL GULF COAST REGION INTO CENTRAL/SOUTHERN GEORGIA AND THE FLORIDA PANHANDLE... ...SUMMARY... A few strong to severe thunderstorms are possible across portions of the central Gulf Coast region into central/southern Georgia and the Florida Panhandle through tonight. ...Synopsis... In mid/upper levels, mean troughing over the central CONUS will evolve from positively to near neutrally tilted through the period, in conjunction with two predominant subsynoptic-scale processes: 1. South-southeastward digging of a cyclone now over extreme northern MB, reaching the MB/ON border east of Lake Winnipeg by 12Z tomorrow; 2. Eastward shift of a strong, basal shortwave trough -- now evident in moisture-channel imagery over northern NM into south-central AZ -- absorbing a weaker/trailing perturbation and reaching from middle TN to central LA by the end of the period. As this occurs, a surface cold front -- analyzed at 11Z from a low near BNA southwestward across northwestern MS, central LA, middle TX Coast, and deep south TX -- should extend from western PA across the southern Appalachians and southwestern AL, to southeastern LA, by 00Z. A low-level, prefrontal confluence/convergence zone may intensify this evening and tonight over portions of the FL Panhandle, southeastern AL and southwestern GA. The cold front should approach and perhaps overtake the confluence zone by 12Z, as it reaches a position from central PA across the western Carolinas, to near a MCN-AAF line, then over the northeastern/central Gulf. ...Southeast... Widely scattered, ongoing thunderstorms clusters are apparent across portions of southern MS into southeastern LA, with a marginal potential for a brief tornado or strong-severe gust. See SPC mesoscale discussion 2255 for near-term coverage of this scenario. Similarly sporadic, isolated and marginal tornado and severe-gust potential will exist throughout today and tonight with convection along and just ahead of the cold front, as well as slowly increasing convective coverage from late afternoon through overnight in the prefrontal convergence zone. The warm-sector environment will remain characterized by a nearly saturated boundary layer with surface dewpoints commonly in the upper 60s to near 70 F along the coast, to mid 60s well inland, amidst nearly moist-adiabatic low-level lapse rates. Somewhat greater boundary-layer instability is possible this afternoon in the inflow to the near-frontal convection, as modest heating occurs through cloud breaks. That my offset weak midlevel lapse rates enough to support peak MLCAPE around 1000 J/kg from southeastern LA to south-central AL, decreasing northeastward as well as eastward. An axis of lesser buoyancy -- with MLCAPE remaining in the 500-800 J/kg range, should shift eastward tonight near the confluence line, in support of convection there. Deep shear should increase from late this afternoon through tonight with the more neutral tilt of the larger-scale trough aloft, and related tightening of the mid/upper height gradient over the warm sector. While strongest flow aloft will remain behind the front, effective-shear magnitudes of 45-55 kt and elongated low-level hodographs are forecast from the northeastern Gulf Coast to the Carolinas. As the basal shortwave trough approaches (but remains behind the cold front), the LLJ should strengthen to 45-55 kt tonight over southern GA, reaching 55-65 kt over eastern NC, with lengthening but only somewhat curved low-level hodographs. The northeastward extent of the conditional severe potential may extend into near-coastal SC/NC; however, poor low- and middle-level lapse rates (with stable layers apparent in forecast soundings) are precluding any expansion of unconditional probabilities northeastward for this outlook cycle. The main (yet marginal) severe threat for the Carolinas still appears to hold off until early day 2. ..Edwards/Jewell.. 12/10/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0639 AM CST Tue Dec 10 2024 Valid 101300Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF THE CENTRAL GULF COAST REGION INTO CENTRAL/SOUTHERN GEORGIA AND THE FLORIDA PANHANDLE... ...SUMMARY... A few strong to severe thunderstorms are possible across portions of the central Gulf Coast region into central/southern Georgia and the Florida Panhandle through tonight. ...Synopsis... In mid/upper levels, mean troughing over the central CONUS will evolve from positively to near neutrally tilted through the period, in conjunction with two predominant subsynoptic-scale processes: 1. South-southeastward digging of a cyclone now over extreme northern MB, reaching the MB/ON border east of Lake Winnipeg by 12Z tomorrow; 2. Eastward shift of a strong, basal shortwave trough -- now evident in moisture-channel imagery over northern NM into south-central AZ -- absorbing a weaker/trailing perturbation and reaching from middle TN to central LA by the end of the period. As this occurs, a surface cold front -- analyzed at 11Z from a low near BNA southwestward across northwestern MS, central LA, middle TX Coast, and deep south TX -- should extend from western PA across the southern Appalachians and southwestern AL, to southeastern LA, by 00Z. A low-level, prefrontal confluence/convergence zone may intensify this evening and tonight over portions of the FL Panhandle, southeastern AL and southwestern GA. The cold front should approach and perhaps overtake the confluence zone by 12Z, as it reaches a position from central PA across the western Carolinas, to near a MCN-AAF line, then over the northeastern/central Gulf. ...Southeast... Widely scattered, ongoing thunderstorms clusters are apparent across portions of southern MS into southeastern LA, with a marginal potential for a brief tornado or strong-severe gust. See SPC mesoscale discussion 2255 for near-term coverage of this scenario. Similarly sporadic, isolated and marginal tornado and severe-gust potential will exist throughout today and tonight with convection along and just ahead of the cold front, as well as slowly increasing convective coverage from late afternoon through overnight in the prefrontal convergence zone. The warm-sector environment will remain characterized by a nearly saturated boundary layer with surface dewpoints commonly in the upper 60s to near 70 F along the coast, to mid 60s well inland, amidst nearly moist-adiabatic low-level lapse rates. Somewhat greater boundary-layer instability is possible this afternoon in the inflow to the near-frontal convection, as modest heating occurs through cloud breaks. That my offset weak midlevel lapse rates enough to support peak MLCAPE around 1000 J/kg from southeastern LA to south-central AL, decreasing northeastward as well as eastward. An axis of lesser buoyancy -- with MLCAPE remaining in the 500-800 J/kg range, should shift eastward tonight near the confluence line, in support of convection there. Deep shear should increase from late this afternoon through tonight with the more neutral tilt of the larger-scale trough aloft, and related tightening of the mid/upper height gradient over the warm sector. While strongest flow aloft will remain behind the front, effective-shear magnitudes of 45-55 kt and elongated low-level hodographs are forecast from the northeastern Gulf Coast to the Carolinas. As the basal shortwave trough approaches (but remains behind the cold front), the LLJ should strengthen to 45-55 kt tonight over southern GA, reaching 55-65 kt over eastern NC, with lengthening but only somewhat curved low-level hodographs. The northeastward extent of the conditional severe potential may extend into near-coastal SC/NC; however, poor low- and middle-level lapse rates (with stable layers apparent in forecast soundings) are precluding any expansion of unconditional probabilities northeastward for this outlook cycle. The main (yet marginal) severe threat for the Carolinas still appears to hold off until early day 2. ..Edwards/Jewell.. 12/10/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0639 AM CST Tue Dec 10 2024 Valid 101300Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF THE CENTRAL GULF COAST REGION INTO CENTRAL/SOUTHERN GEORGIA AND THE FLORIDA PANHANDLE... ...SUMMARY... A few strong to severe thunderstorms are possible across portions of the central Gulf Coast region into central/southern Georgia and the Florida Panhandle through tonight. ...Synopsis... In mid/upper levels, mean troughing over the central CONUS will evolve from positively to near neutrally tilted through the period, in conjunction with two predominant subsynoptic-scale processes: 1. South-southeastward digging of a cyclone now over extreme northern MB, reaching the MB/ON border east of Lake Winnipeg by 12Z tomorrow; 2. Eastward shift of a strong, basal shortwave trough -- now evident in moisture-channel imagery over northern NM into south-central AZ -- absorbing a weaker/trailing perturbation and reaching from middle TN to central LA by the end of the period. As this occurs, a surface cold front -- analyzed at 11Z from a low near BNA southwestward across northwestern MS, central LA, middle TX Coast, and deep south TX -- should extend from western PA across the southern Appalachians and southwestern AL, to southeastern LA, by 00Z. A low-level, prefrontal confluence/convergence zone may intensify this evening and tonight over portions of the FL Panhandle, southeastern AL and southwestern GA. The cold front should approach and perhaps overtake the confluence zone by 12Z, as it reaches a position from central PA across the western Carolinas, to near a MCN-AAF line, then over the northeastern/central Gulf. ...Southeast... Widely scattered, ongoing thunderstorms clusters are apparent across portions of southern MS into southeastern LA, with a marginal potential for a brief tornado or strong-severe gust. See SPC mesoscale discussion 2255 for near-term coverage of this scenario. Similarly sporadic, isolated and marginal tornado and severe-gust potential will exist throughout today and tonight with convection along and just ahead of the cold front, as well as slowly increasing convective coverage from late afternoon through overnight in the prefrontal convergence zone. The warm-sector environment will remain characterized by a nearly saturated boundary layer with surface dewpoints commonly in the upper 60s to near 70 F along the coast, to mid 60s well inland, amidst nearly moist-adiabatic low-level lapse rates. Somewhat greater boundary-layer instability is possible this afternoon in the inflow to the near-frontal convection, as modest heating occurs through cloud breaks. That my offset weak midlevel lapse rates enough to support peak MLCAPE around 1000 J/kg from southeastern LA to south-central AL, decreasing northeastward as well as eastward. An axis of lesser buoyancy -- with MLCAPE remaining in the 500-800 J/kg range, should shift eastward tonight near the confluence line, in support of convection there. Deep shear should increase from late this afternoon through tonight with the more neutral tilt of the larger-scale trough aloft, and related tightening of the mid/upper height gradient over the warm sector. While strongest flow aloft will remain behind the front, effective-shear magnitudes of 45-55 kt and elongated low-level hodographs are forecast from the northeastern Gulf Coast to the Carolinas. As the basal shortwave trough approaches (but remains behind the cold front), the LLJ should strengthen to 45-55 kt tonight over southern GA, reaching 55-65 kt over eastern NC, with lengthening but only somewhat curved low-level hodographs. The northeastward extent of the conditional severe potential may extend into near-coastal SC/NC; however, poor low- and middle-level lapse rates (with stable layers apparent in forecast soundings) are precluding any expansion of unconditional probabilities northeastward for this outlook cycle. The main (yet marginal) severe threat for the Carolinas still appears to hold off until early day 2. ..Edwards/Jewell.. 12/10/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0639 AM CST Tue Dec 10 2024 Valid 101300Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF THE CENTRAL GULF COAST REGION INTO CENTRAL/SOUTHERN GEORGIA AND THE FLORIDA PANHANDLE... ...SUMMARY... A few strong to severe thunderstorms are possible across portions of the central Gulf Coast region into central/southern Georgia and the Florida Panhandle through tonight. ...Synopsis... In mid/upper levels, mean troughing over the central CONUS will evolve from positively to near neutrally tilted through the period, in conjunction with two predominant subsynoptic-scale processes: 1. South-southeastward digging of a cyclone now over extreme northern MB, reaching the MB/ON border east of Lake Winnipeg by 12Z tomorrow; 2. Eastward shift of a strong, basal shortwave trough -- now evident in moisture-channel imagery over northern NM into south-central AZ -- absorbing a weaker/trailing perturbation and reaching from middle TN to central LA by the end of the period. As this occurs, a surface cold front -- analyzed at 11Z from a low near BNA southwestward across northwestern MS, central LA, middle TX Coast, and deep south TX -- should extend from western PA across the southern Appalachians and southwestern AL, to southeastern LA, by 00Z. A low-level, prefrontal confluence/convergence zone may intensify this evening and tonight over portions of the FL Panhandle, southeastern AL and southwestern GA. The cold front should approach and perhaps overtake the confluence zone by 12Z, as it reaches a position from central PA across the western Carolinas, to near a MCN-AAF line, then over the northeastern/central Gulf. ...Southeast... Widely scattered, ongoing thunderstorms clusters are apparent across portions of southern MS into southeastern LA, with a marginal potential for a brief tornado or strong-severe gust. See SPC mesoscale discussion 2255 for near-term coverage of this scenario. Similarly sporadic, isolated and marginal tornado and severe-gust potential will exist throughout today and tonight with convection along and just ahead of the cold front, as well as slowly increasing convective coverage from late afternoon through overnight in the prefrontal convergence zone. The warm-sector environment will remain characterized by a nearly saturated boundary layer with surface dewpoints commonly in the upper 60s to near 70 F along the coast, to mid 60s well inland, amidst nearly moist-adiabatic low-level lapse rates. Somewhat greater boundary-layer instability is possible this afternoon in the inflow to the near-frontal convection, as modest heating occurs through cloud breaks. That my offset weak midlevel lapse rates enough to support peak MLCAPE around 1000 J/kg from southeastern LA to south-central AL, decreasing northeastward as well as eastward. An axis of lesser buoyancy -- with MLCAPE remaining in the 500-800 J/kg range, should shift eastward tonight near the confluence line, in support of convection there. Deep shear should increase from late this afternoon through tonight with the more neutral tilt of the larger-scale trough aloft, and related tightening of the mid/upper height gradient over the warm sector. While strongest flow aloft will remain behind the front, effective-shear magnitudes of 45-55 kt and elongated low-level hodographs are forecast from the northeastern Gulf Coast to the Carolinas. As the basal shortwave trough approaches (but remains behind the cold front), the LLJ should strengthen to 45-55 kt tonight over southern GA, reaching 55-65 kt over eastern NC, with lengthening but only somewhat curved low-level hodographs. The northeastward extent of the conditional severe potential may extend into near-coastal SC/NC; however, poor low- and middle-level lapse rates (with stable layers apparent in forecast soundings) are precluding any expansion of unconditional probabilities northeastward for this outlook cycle. The main (yet marginal) severe threat for the Carolinas still appears to hold off until early day 2. ..Edwards/Jewell.. 12/10/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0639 AM CST Tue Dec 10 2024 Valid 101300Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF THE CENTRAL GULF COAST REGION INTO CENTRAL/SOUTHERN GEORGIA AND THE FLORIDA PANHANDLE... ...SUMMARY... A few strong to severe thunderstorms are possible across portions of the central Gulf Coast region into central/southern Georgia and the Florida Panhandle through tonight. ...Synopsis... In mid/upper levels, mean troughing over the central CONUS will evolve from positively to near neutrally tilted through the period, in conjunction with two predominant subsynoptic-scale processes: 1. South-southeastward digging of a cyclone now over extreme northern MB, reaching the MB/ON border east of Lake Winnipeg by 12Z tomorrow; 2. Eastward shift of a strong, basal shortwave trough -- now evident in moisture-channel imagery over northern NM into south-central AZ -- absorbing a weaker/trailing perturbation and reaching from middle TN to central LA by the end of the period. As this occurs, a surface cold front -- analyzed at 11Z from a low near BNA southwestward across northwestern MS, central LA, middle TX Coast, and deep south TX -- should extend from western PA across the southern Appalachians and southwestern AL, to southeastern LA, by 00Z. A low-level, prefrontal confluence/convergence zone may intensify this evening and tonight over portions of the FL Panhandle, southeastern AL and southwestern GA. The cold front should approach and perhaps overtake the confluence zone by 12Z, as it reaches a position from central PA across the western Carolinas, to near a MCN-AAF line, then over the northeastern/central Gulf. ...Southeast... Widely scattered, ongoing thunderstorms clusters are apparent across portions of southern MS into southeastern LA, with a marginal potential for a brief tornado or strong-severe gust. See SPC mesoscale discussion 2255 for near-term coverage of this scenario. Similarly sporadic, isolated and marginal tornado and severe-gust potential will exist throughout today and tonight with convection along and just ahead of the cold front, as well as slowly increasing convective coverage from late afternoon through overnight in the prefrontal convergence zone. The warm-sector environment will remain characterized by a nearly saturated boundary layer with surface dewpoints commonly in the upper 60s to near 70 F along the coast, to mid 60s well inland, amidst nearly moist-adiabatic low-level lapse rates. Somewhat greater boundary-layer instability is possible this afternoon in the inflow to the near-frontal convection, as modest heating occurs through cloud breaks. That my offset weak midlevel lapse rates enough to support peak MLCAPE around 1000 J/kg from southeastern LA to south-central AL, decreasing northeastward as well as eastward. An axis of lesser buoyancy -- with MLCAPE remaining in the 500-800 J/kg range, should shift eastward tonight near the confluence line, in support of convection there. Deep shear should increase from late this afternoon through tonight with the more neutral tilt of the larger-scale trough aloft, and related tightening of the mid/upper height gradient over the warm sector. While strongest flow aloft will remain behind the front, effective-shear magnitudes of 45-55 kt and elongated low-level hodographs are forecast from the northeastern Gulf Coast to the Carolinas. As the basal shortwave trough approaches (but remains behind the cold front), the LLJ should strengthen to 45-55 kt tonight over southern GA, reaching 55-65 kt over eastern NC, with lengthening but only somewhat curved low-level hodographs. The northeastward extent of the conditional severe potential may extend into near-coastal SC/NC; however, poor low- and middle-level lapse rates (with stable layers apparent in forecast soundings) are precluding any expansion of unconditional probabilities northeastward for this outlook cycle. The main (yet marginal) severe threat for the Carolinas still appears to hold off until early day 2. ..Edwards/Jewell.. 12/10/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0639 AM CST Tue Dec 10 2024 Valid 101300Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF THE CENTRAL GULF COAST REGION INTO CENTRAL/SOUTHERN GEORGIA AND THE FLORIDA PANHANDLE... ...SUMMARY... A few strong to severe thunderstorms are possible across portions of the central Gulf Coast region into central/southern Georgia and the Florida Panhandle through tonight. ...Synopsis... In mid/upper levels, mean troughing over the central CONUS will evolve from positively to near neutrally tilted through the period, in conjunction with two predominant subsynoptic-scale processes: 1. South-southeastward digging of a cyclone now over extreme northern MB, reaching the MB/ON border east of Lake Winnipeg by 12Z tomorrow; 2. Eastward shift of a strong, basal shortwave trough -- now evident in moisture-channel imagery over northern NM into south-central AZ -- absorbing a weaker/trailing perturbation and reaching from middle TN to central LA by the end of the period. As this occurs, a surface cold front -- analyzed at 11Z from a low near BNA southwestward across northwestern MS, central LA, middle TX Coast, and deep south TX -- should extend from western PA across the southern Appalachians and southwestern AL, to southeastern LA, by 00Z. A low-level, prefrontal confluence/convergence zone may intensify this evening and tonight over portions of the FL Panhandle, southeastern AL and southwestern GA. The cold front should approach and perhaps overtake the confluence zone by 12Z, as it reaches a position from central PA across the western Carolinas, to near a MCN-AAF line, then over the northeastern/central Gulf. ...Southeast... Widely scattered, ongoing thunderstorms clusters are apparent across portions of southern MS into southeastern LA, with a marginal potential for a brief tornado or strong-severe gust. See SPC mesoscale discussion 2255 for near-term coverage of this scenario. Similarly sporadic, isolated and marginal tornado and severe-gust potential will exist throughout today and tonight with convection along and just ahead of the cold front, as well as slowly increasing convective coverage from late afternoon through overnight in the prefrontal convergence zone. The warm-sector environment will remain characterized by a nearly saturated boundary layer with surface dewpoints commonly in the upper 60s to near 70 F along the coast, to mid 60s well inland, amidst nearly moist-adiabatic low-level lapse rates. Somewhat greater boundary-layer instability is possible this afternoon in the inflow to the near-frontal convection, as modest heating occurs through cloud breaks. That my offset weak midlevel lapse rates enough to support peak MLCAPE around 1000 J/kg from southeastern LA to south-central AL, decreasing northeastward as well as eastward. An axis of lesser buoyancy -- with MLCAPE remaining in the 500-800 J/kg range, should shift eastward tonight near the confluence line, in support of convection there. Deep shear should increase from late this afternoon through tonight with the more neutral tilt of the larger-scale trough aloft, and related tightening of the mid/upper height gradient over the warm sector. While strongest flow aloft will remain behind the front, effective-shear magnitudes of 45-55 kt and elongated low-level hodographs are forecast from the northeastern Gulf Coast to the Carolinas. As the basal shortwave trough approaches (but remains behind the cold front), the LLJ should strengthen to 45-55 kt tonight over southern GA, reaching 55-65 kt over eastern NC, with lengthening but only somewhat curved low-level hodographs. The northeastward extent of the conditional severe potential may extend into near-coastal SC/NC; however, poor low- and middle-level lapse rates (with stable layers apparent in forecast soundings) are precluding any expansion of unconditional probabilities northeastward for this outlook cycle. The main (yet marginal) severe threat for the Carolinas still appears to hold off until early day 2. ..Edwards/Jewell.. 12/10/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CST Tue Dec 10 2024 Valid 131200Z - 181200Z ...DISCUSSION... Medium-range guidance is in good agreement that a shortwave trough will move from the central Rockies through the central Plains on D4/Friday. An associated surface low will take a similar track just ahead of the parent wave, with an attendant cold front pushing eastward across the southern/central Plains. Some modest moisture return will precede this front, and thunderstorms appear possible from east TX into the Lower MO Valley D4/Friday night into D5/Saturday morning. A few strong storms are possible, but overall buoyancy will likely remain modest due to warm mid-level temperatures, and the highest dewpoints are expected to remain displaced south of the better forcing. This shortwave and attendant cold front will likely continue eastward on into the MS Valley on D5/Saturday and through the remainder of the eastern CONUS on D6/Sunday. Thunderstorms are possible over portions of the Lower MS Valley and Mid-South on D5/Saturday and the Carolinas on D6/Sunday. Limited buoyancy should keep any severe-weather threat isolated. Another shortwave trough is expected to move across CA and the Great Basin on D6/Sunday and through the central Plains and Mid MS Valley on D7/Monday. Similar to the earlier shortwave, the strongest forcing for ascent with this shortwave is expected to remain displaced north of the better low-level moisture and buoyancy, likely tempering the overall severe potential. Even so, thunderstorms are possible, and greater moisture return (and buoyancy) is possible if the preceding cold front remains weak over the southern Plains. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CST Tue Dec 10 2024 Valid 131200Z - 181200Z ...DISCUSSION... Medium-range guidance is in good agreement that a shortwave trough will move from the central Rockies through the central Plains on D4/Friday. An associated surface low will take a similar track just ahead of the parent wave, with an attendant cold front pushing eastward across the southern/central Plains. Some modest moisture return will precede this front, and thunderstorms appear possible from east TX into the Lower MO Valley D4/Friday night into D5/Saturday morning. A few strong storms are possible, but overall buoyancy will likely remain modest due to warm mid-level temperatures, and the highest dewpoints are expected to remain displaced south of the better forcing. This shortwave and attendant cold front will likely continue eastward on into the MS Valley on D5/Saturday and through the remainder of the eastern CONUS on D6/Sunday. Thunderstorms are possible over portions of the Lower MS Valley and Mid-South on D5/Saturday and the Carolinas on D6/Sunday. Limited buoyancy should keep any severe-weather threat isolated. Another shortwave trough is expected to move across CA and the Great Basin on D6/Sunday and through the central Plains and Mid MS Valley on D7/Monday. Similar to the earlier shortwave, the strongest forcing for ascent with this shortwave is expected to remain displaced north of the better low-level moisture and buoyancy, likely tempering the overall severe potential. Even so, thunderstorms are possible, and greater moisture return (and buoyancy) is possible if the preceding cold front remains weak over the southern Plains. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CST Tue Dec 10 2024 Valid 131200Z - 181200Z ...DISCUSSION... Medium-range guidance is in good agreement that a shortwave trough will move from the central Rockies through the central Plains on D4/Friday. An associated surface low will take a similar track just ahead of the parent wave, with an attendant cold front pushing eastward across the southern/central Plains. Some modest moisture return will precede this front, and thunderstorms appear possible from east TX into the Lower MO Valley D4/Friday night into D5/Saturday morning. A few strong storms are possible, but overall buoyancy will likely remain modest due to warm mid-level temperatures, and the highest dewpoints are expected to remain displaced south of the better forcing. This shortwave and attendant cold front will likely continue eastward on into the MS Valley on D5/Saturday and through the remainder of the eastern CONUS on D6/Sunday. Thunderstorms are possible over portions of the Lower MS Valley and Mid-South on D5/Saturday and the Carolinas on D6/Sunday. Limited buoyancy should keep any severe-weather threat isolated. Another shortwave trough is expected to move across CA and the Great Basin on D6/Sunday and through the central Plains and Mid MS Valley on D7/Monday. Similar to the earlier shortwave, the strongest forcing for ascent with this shortwave is expected to remain displaced north of the better low-level moisture and buoyancy, likely tempering the overall severe potential. Even so, thunderstorms are possible, and greater moisture return (and buoyancy) is possible if the preceding cold front remains weak over the southern Plains. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CST Tue Dec 10 2024 Valid 131200Z - 181200Z ...DISCUSSION... Medium-range guidance is in good agreement that a shortwave trough will move from the central Rockies through the central Plains on D4/Friday. An associated surface low will take a similar track just ahead of the parent wave, with an attendant cold front pushing eastward across the southern/central Plains. Some modest moisture return will precede this front, and thunderstorms appear possible from east TX into the Lower MO Valley D4/Friday night into D5/Saturday morning. A few strong storms are possible, but overall buoyancy will likely remain modest due to warm mid-level temperatures, and the highest dewpoints are expected to remain displaced south of the better forcing. This shortwave and attendant cold front will likely continue eastward on into the MS Valley on D5/Saturday and through the remainder of the eastern CONUS on D6/Sunday. Thunderstorms are possible over portions of the Lower MS Valley and Mid-South on D5/Saturday and the Carolinas on D6/Sunday. Limited buoyancy should keep any severe-weather threat isolated. Another shortwave trough is expected to move across CA and the Great Basin on D6/Sunday and through the central Plains and Mid MS Valley on D7/Monday. Similar to the earlier shortwave, the strongest forcing for ascent with this shortwave is expected to remain displaced north of the better low-level moisture and buoyancy, likely tempering the overall severe potential. Even so, thunderstorms are possible, and greater moisture return (and buoyancy) is possible if the preceding cold front remains weak over the southern Plains. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CST Tue Dec 10 2024 Valid 131200Z - 181200Z ...DISCUSSION... Medium-range guidance is in good agreement that a shortwave trough will move from the central Rockies through the central Plains on D4/Friday. An associated surface low will take a similar track just ahead of the parent wave, with an attendant cold front pushing eastward across the southern/central Plains. Some modest moisture return will precede this front, and thunderstorms appear possible from east TX into the Lower MO Valley D4/Friday night into D5/Saturday morning. A few strong storms are possible, but overall buoyancy will likely remain modest due to warm mid-level temperatures, and the highest dewpoints are expected to remain displaced south of the better forcing. This shortwave and attendant cold front will likely continue eastward on into the MS Valley on D5/Saturday and through the remainder of the eastern CONUS on D6/Sunday. Thunderstorms are possible over portions of the Lower MS Valley and Mid-South on D5/Saturday and the Carolinas on D6/Sunday. Limited buoyancy should keep any severe-weather threat isolated. Another shortwave trough is expected to move across CA and the Great Basin on D6/Sunday and through the central Plains and Mid MS Valley on D7/Monday. Similar to the earlier shortwave, the strongest forcing for ascent with this shortwave is expected to remain displaced north of the better low-level moisture and buoyancy, likely tempering the overall severe potential. Even so, thunderstorms are possible, and greater moisture return (and buoyancy) is possible if the preceding cold front remains weak over the southern Plains. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CST Tue Dec 10 2024 Valid 131200Z - 181200Z ...DISCUSSION... Medium-range guidance is in good agreement that a shortwave trough will move from the central Rockies through the central Plains on D4/Friday. An associated surface low will take a similar track just ahead of the parent wave, with an attendant cold front pushing eastward across the southern/central Plains. Some modest moisture return will precede this front, and thunderstorms appear possible from east TX into the Lower MO Valley D4/Friday night into D5/Saturday morning. A few strong storms are possible, but overall buoyancy will likely remain modest due to warm mid-level temperatures, and the highest dewpoints are expected to remain displaced south of the better forcing. This shortwave and attendant cold front will likely continue eastward on into the MS Valley on D5/Saturday and through the remainder of the eastern CONUS on D6/Sunday. Thunderstorms are possible over portions of the Lower MS Valley and Mid-South on D5/Saturday and the Carolinas on D6/Sunday. Limited buoyancy should keep any severe-weather threat isolated. Another shortwave trough is expected to move across CA and the Great Basin on D6/Sunday and through the central Plains and Mid MS Valley on D7/Monday. Similar to the earlier shortwave, the strongest forcing for ascent with this shortwave is expected to remain displaced north of the better low-level moisture and buoyancy, likely tempering the overall severe potential. Even so, thunderstorms are possible, and greater moisture return (and buoyancy) is possible if the preceding cold front remains weak over the southern Plains. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CST Tue Dec 10 2024 Valid 131200Z - 181200Z ...DISCUSSION... Medium-range guidance is in good agreement that a shortwave trough will move from the central Rockies through the central Plains on D4/Friday. An associated surface low will take a similar track just ahead of the parent wave, with an attendant cold front pushing eastward across the southern/central Plains. Some modest moisture return will precede this front, and thunderstorms appear possible from east TX into the Lower MO Valley D4/Friday night into D5/Saturday morning. A few strong storms are possible, but overall buoyancy will likely remain modest due to warm mid-level temperatures, and the highest dewpoints are expected to remain displaced south of the better forcing. This shortwave and attendant cold front will likely continue eastward on into the MS Valley on D5/Saturday and through the remainder of the eastern CONUS on D6/Sunday. Thunderstorms are possible over portions of the Lower MS Valley and Mid-South on D5/Saturday and the Carolinas on D6/Sunday. Limited buoyancy should keep any severe-weather threat isolated. Another shortwave trough is expected to move across CA and the Great Basin on D6/Sunday and through the central Plains and Mid MS Valley on D7/Monday. Similar to the earlier shortwave, the strongest forcing for ascent with this shortwave is expected to remain displaced north of the better low-level moisture and buoyancy, likely tempering the overall severe potential. Even so, thunderstorms are possible, and greater moisture return (and buoyancy) is possible if the preceding cold front remains weak over the southern Plains. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CST Tue Dec 10 2024 Valid 131200Z - 181200Z ...DISCUSSION... Medium-range guidance is in good agreement that a shortwave trough will move from the central Rockies through the central Plains on D4/Friday. An associated surface low will take a similar track just ahead of the parent wave, with an attendant cold front pushing eastward across the southern/central Plains. Some modest moisture return will precede this front, and thunderstorms appear possible from east TX into the Lower MO Valley D4/Friday night into D5/Saturday morning. A few strong storms are possible, but overall buoyancy will likely remain modest due to warm mid-level temperatures, and the highest dewpoints are expected to remain displaced south of the better forcing. This shortwave and attendant cold front will likely continue eastward on into the MS Valley on D5/Saturday and through the remainder of the eastern CONUS on D6/Sunday. Thunderstorms are possible over portions of the Lower MS Valley and Mid-South on D5/Saturday and the Carolinas on D6/Sunday. Limited buoyancy should keep any severe-weather threat isolated. Another shortwave trough is expected to move across CA and the Great Basin on D6/Sunday and through the central Plains and Mid MS Valley on D7/Monday. Similar to the earlier shortwave, the strongest forcing for ascent with this shortwave is expected to remain displaced north of the better low-level moisture and buoyancy, likely tempering the overall severe potential. Even so, thunderstorms are possible, and greater moisture return (and buoyancy) is possible if the preceding cold front remains weak over the southern Plains. Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0204 AM CST Tue Dec 10 2024 Valid 121200Z - 131200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are not expected on Thursday. ...Synopsis... A mid/upper cyclone is forecast to be over the Ontario/Quebec vicinity early Thursday morning, with cyclonic flow throughout its base extending from the northern/central Plains through the Northeast. This cyclone is expected to gradually shift eastward through Quebec, with the associated cyclonic flow shifting northward and eastward as well. Farther west, a low-amplitude shortwave trough is expected to progress across the Great Basin into the Four Corners region while enhanced mid-level westerly flow associated with it spreads from southern CA across the Southwest. At the surface, extensive ridging is expected from the northern Plains into much of the eastern CONUS, promoting dry and stable conditions. Modest lee troughing is anticipated across the High Plains ahead of the approaching shortwave. However, scouring of the low-level moisture by an antecedent frontal passage will limit moisture advection, with stable conditions prevailing across the central and southern Plains as well. ..Mosier.. 12/10/2024 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0204 AM CST Tue Dec 10 2024 Valid 121200Z - 131200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are not expected on Thursday. ...Synopsis... A mid/upper cyclone is forecast to be over the Ontario/Quebec vicinity early Thursday morning, with cyclonic flow throughout its base extending from the northern/central Plains through the Northeast. This cyclone is expected to gradually shift eastward through Quebec, with the associated cyclonic flow shifting northward and eastward as well. Farther west, a low-amplitude shortwave trough is expected to progress across the Great Basin into the Four Corners region while enhanced mid-level westerly flow associated with it spreads from southern CA across the Southwest. At the surface, extensive ridging is expected from the northern Plains into much of the eastern CONUS, promoting dry and stable conditions. Modest lee troughing is anticipated across the High Plains ahead of the approaching shortwave. However, scouring of the low-level moisture by an antecedent frontal passage will limit moisture advection, with stable conditions prevailing across the central and southern Plains as well. ..Mosier.. 12/10/2024 Read more