Severe Storms

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1044 AM CST Sat Dec 02 2023 Valid 021700Z - 031200Z ...NO CRITICAL AREAS... No changes. See previous discussion below. ..Bentley.. 12/02/2023 .PREV DISCUSSION... /ISSUED 1230 AM CST Sat Dec 02 2023/ ...Synopsis... A shortwave will rotate through the longwave trough located across the Central CONUS today bringing enhanced mid-level westerly flow across the Four Corners into New Mexico. Warm and dry downslope flow across the High Plains will bring relative humidity reductions to around 15-20 percent across the Texas and Oklahoma Panhandles into portions of far western Texas, with sustained winds around 15-25 mph (locally higher). Fuels within these regions remain moist, which will help mitigate concerns over fire spread. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1024 AM CST Sat Dec 02 2023 Valid 021630Z - 031200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL AND NORTHEASTERN GULF COAST STATES... ...SUMMARY... Isolated severe storms are possible over parts of the central/ northeastern Gulf Coast today and tonight. ...Synopsis... A mid-level shortwave trough and accompanying broad cyclonic flow aloft will progress eastward over the eastern half of the CONUS as a second, upstream shortwave over the northern Rockies begins to amplify. To the West, ridging will slowly build over the eastern Pacific, shunting stronger flow aloft northward toward the Canadian border. At the surface, a cold front was observed stretching from the Ohio Valley to the MS Delta, with a diffuse and decaying warm front located just offshore. A broad and weak wave cyclone, along the cold front, should progress northeastward reaching the upper OH River valley by 12z Sun. ...Central and northeast Gulf Coast... Morning observations show widespread precipitation and convection ongoing north of the weakening warm front across parts of eastern LA southern MS/AL and the western FL Panhandle. Despite relatively moist surface conditions, much of the true warm sector remains offshore. In the absence of stronger mass response from weak forcing for ascent, low-level warm air advection is expected to remain weak as the broad surface low slowly traverses along the front to the northeast. Widespread cloud debris and ongoing precipitation also strongly suggest destabilization will remain quite limited inland. Still, 500-1000 J/kg of MUCAPE and 35-45 kt of effective shear should be sufficient to support a few stronger updrafts as convection continually redevelops off the Gulf. A few of these stronger cells may eventually move inland with the potential for isolated damaging wind gusts or a brief tornado along the immediate coast. Deep-layer shear and hodograph size should gradually decrease through the day as the warm sector becomes increasingly separated from the shortwave trough lifting away. While a few clusters of storms should persist into this evening, the severe threat should gradually wane from west to east as the cold front moves eastward. ..Lyons/Hart.. 12/02/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1024 AM CST Sat Dec 02 2023 Valid 021630Z - 031200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL AND NORTHEASTERN GULF COAST STATES... ...SUMMARY... Isolated severe storms are possible over parts of the central/ northeastern Gulf Coast today and tonight. ...Synopsis... A mid-level shortwave trough and accompanying broad cyclonic flow aloft will progress eastward over the eastern half of the CONUS as a second, upstream shortwave over the northern Rockies begins to amplify. To the West, ridging will slowly build over the eastern Pacific, shunting stronger flow aloft northward toward the Canadian border. At the surface, a cold front was observed stretching from the Ohio Valley to the MS Delta, with a diffuse and decaying warm front located just offshore. A broad and weak wave cyclone, along the cold front, should progress northeastward reaching the upper OH River valley by 12z Sun. ...Central and northeast Gulf Coast... Morning observations show widespread precipitation and convection ongoing north of the weakening warm front across parts of eastern LA southern MS/AL and the western FL Panhandle. Despite relatively moist surface conditions, much of the true warm sector remains offshore. In the absence of stronger mass response from weak forcing for ascent, low-level warm air advection is expected to remain weak as the broad surface low slowly traverses along the front to the northeast. Widespread cloud debris and ongoing precipitation also strongly suggest destabilization will remain quite limited inland. Still, 500-1000 J/kg of MUCAPE and 35-45 kt of effective shear should be sufficient to support a few stronger updrafts as convection continually redevelops off the Gulf. A few of these stronger cells may eventually move inland with the potential for isolated damaging wind gusts or a brief tornado along the immediate coast. Deep-layer shear and hodograph size should gradually decrease through the day as the warm sector becomes increasingly separated from the shortwave trough lifting away. While a few clusters of storms should persist into this evening, the severe threat should gradually wane from west to east as the cold front moves eastward. ..Lyons/Hart.. 12/02/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1024 AM CST Sat Dec 02 2023 Valid 021630Z - 031200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL AND NORTHEASTERN GULF COAST STATES... ...SUMMARY... Isolated severe storms are possible over parts of the central/ northeastern Gulf Coast today and tonight. ...Synopsis... A mid-level shortwave trough and accompanying broad cyclonic flow aloft will progress eastward over the eastern half of the CONUS as a second, upstream shortwave over the northern Rockies begins to amplify. To the West, ridging will slowly build over the eastern Pacific, shunting stronger flow aloft northward toward the Canadian border. At the surface, a cold front was observed stretching from the Ohio Valley to the MS Delta, with a diffuse and decaying warm front located just offshore. A broad and weak wave cyclone, along the cold front, should progress northeastward reaching the upper OH River valley by 12z Sun. ...Central and northeast Gulf Coast... Morning observations show widespread precipitation and convection ongoing north of the weakening warm front across parts of eastern LA southern MS/AL and the western FL Panhandle. Despite relatively moist surface conditions, much of the true warm sector remains offshore. In the absence of stronger mass response from weak forcing for ascent, low-level warm air advection is expected to remain weak as the broad surface low slowly traverses along the front to the northeast. Widespread cloud debris and ongoing precipitation also strongly suggest destabilization will remain quite limited inland. Still, 500-1000 J/kg of MUCAPE and 35-45 kt of effective shear should be sufficient to support a few stronger updrafts as convection continually redevelops off the Gulf. A few of these stronger cells may eventually move inland with the potential for isolated damaging wind gusts or a brief tornado along the immediate coast. Deep-layer shear and hodograph size should gradually decrease through the day as the warm sector becomes increasingly separated from the shortwave trough lifting away. While a few clusters of storms should persist into this evening, the severe threat should gradually wane from west to east as the cold front moves eastward. ..Lyons/Hart.. 12/02/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1024 AM CST Sat Dec 02 2023 Valid 021630Z - 031200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL AND NORTHEASTERN GULF COAST STATES... ...SUMMARY... Isolated severe storms are possible over parts of the central/ northeastern Gulf Coast today and tonight. ...Synopsis... A mid-level shortwave trough and accompanying broad cyclonic flow aloft will progress eastward over the eastern half of the CONUS as a second, upstream shortwave over the northern Rockies begins to amplify. To the West, ridging will slowly build over the eastern Pacific, shunting stronger flow aloft northward toward the Canadian border. At the surface, a cold front was observed stretching from the Ohio Valley to the MS Delta, with a diffuse and decaying warm front located just offshore. A broad and weak wave cyclone, along the cold front, should progress northeastward reaching the upper OH River valley by 12z Sun. ...Central and northeast Gulf Coast... Morning observations show widespread precipitation and convection ongoing north of the weakening warm front across parts of eastern LA southern MS/AL and the western FL Panhandle. Despite relatively moist surface conditions, much of the true warm sector remains offshore. In the absence of stronger mass response from weak forcing for ascent, low-level warm air advection is expected to remain weak as the broad surface low slowly traverses along the front to the northeast. Widespread cloud debris and ongoing precipitation also strongly suggest destabilization will remain quite limited inland. Still, 500-1000 J/kg of MUCAPE and 35-45 kt of effective shear should be sufficient to support a few stronger updrafts as convection continually redevelops off the Gulf. A few of these stronger cells may eventually move inland with the potential for isolated damaging wind gusts or a brief tornado along the immediate coast. Deep-layer shear and hodograph size should gradually decrease through the day as the warm sector becomes increasingly separated from the shortwave trough lifting away. While a few clusters of storms should persist into this evening, the severe threat should gradually wane from west to east as the cold front moves eastward. ..Lyons/Hart.. 12/02/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1024 AM CST Sat Dec 02 2023 Valid 021630Z - 031200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL AND NORTHEASTERN GULF COAST STATES... ...SUMMARY... Isolated severe storms are possible over parts of the central/ northeastern Gulf Coast today and tonight. ...Synopsis... A mid-level shortwave trough and accompanying broad cyclonic flow aloft will progress eastward over the eastern half of the CONUS as a second, upstream shortwave over the northern Rockies begins to amplify. To the West, ridging will slowly build over the eastern Pacific, shunting stronger flow aloft northward toward the Canadian border. At the surface, a cold front was observed stretching from the Ohio Valley to the MS Delta, with a diffuse and decaying warm front located just offshore. A broad and weak wave cyclone, along the cold front, should progress northeastward reaching the upper OH River valley by 12z Sun. ...Central and northeast Gulf Coast... Morning observations show widespread precipitation and convection ongoing north of the weakening warm front across parts of eastern LA southern MS/AL and the western FL Panhandle. Despite relatively moist surface conditions, much of the true warm sector remains offshore. In the absence of stronger mass response from weak forcing for ascent, low-level warm air advection is expected to remain weak as the broad surface low slowly traverses along the front to the northeast. Widespread cloud debris and ongoing precipitation also strongly suggest destabilization will remain quite limited inland. Still, 500-1000 J/kg of MUCAPE and 35-45 kt of effective shear should be sufficient to support a few stronger updrafts as convection continually redevelops off the Gulf. A few of these stronger cells may eventually move inland with the potential for isolated damaging wind gusts or a brief tornado along the immediate coast. Deep-layer shear and hodograph size should gradually decrease through the day as the warm sector becomes increasingly separated from the shortwave trough lifting away. While a few clusters of storms should persist into this evening, the severe threat should gradually wane from west to east as the cold front moves eastward. ..Lyons/Hart.. 12/02/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1024 AM CST Sat Dec 02 2023 Valid 021630Z - 031200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL AND NORTHEASTERN GULF COAST STATES... ...SUMMARY... Isolated severe storms are possible over parts of the central/ northeastern Gulf Coast today and tonight. ...Synopsis... A mid-level shortwave trough and accompanying broad cyclonic flow aloft will progress eastward over the eastern half of the CONUS as a second, upstream shortwave over the northern Rockies begins to amplify. To the West, ridging will slowly build over the eastern Pacific, shunting stronger flow aloft northward toward the Canadian border. At the surface, a cold front was observed stretching from the Ohio Valley to the MS Delta, with a diffuse and decaying warm front located just offshore. A broad and weak wave cyclone, along the cold front, should progress northeastward reaching the upper OH River valley by 12z Sun. ...Central and northeast Gulf Coast... Morning observations show widespread precipitation and convection ongoing north of the weakening warm front across parts of eastern LA southern MS/AL and the western FL Panhandle. Despite relatively moist surface conditions, much of the true warm sector remains offshore. In the absence of stronger mass response from weak forcing for ascent, low-level warm air advection is expected to remain weak as the broad surface low slowly traverses along the front to the northeast. Widespread cloud debris and ongoing precipitation also strongly suggest destabilization will remain quite limited inland. Still, 500-1000 J/kg of MUCAPE and 35-45 kt of effective shear should be sufficient to support a few stronger updrafts as convection continually redevelops off the Gulf. A few of these stronger cells may eventually move inland with the potential for isolated damaging wind gusts or a brief tornado along the immediate coast. Deep-layer shear and hodograph size should gradually decrease through the day as the warm sector becomes increasingly separated from the shortwave trough lifting away. While a few clusters of storms should persist into this evening, the severe threat should gradually wane from west to east as the cold front moves eastward. ..Lyons/Hart.. 12/02/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0643 AM CST Sat Dec 02 2023 Valid 021300Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NEAR THE COAST OF THE FLORIDA PANHANDLE AND A SMALL PART OF SOUTHWESTERN ALABAMA... ...SUMMARY... Isolated severe storms are possible over parts of the north-central/ northeastern Gulf Coast region. ...Synopsis... A mid/upper-level, synoptic-scale trough, with associated cyclonic flow traversed by several shortwave perturbations/vorticity lobes -- is expected to move eastward from its present position over the Rocky Mountain States. Leading/basal shortwave troughs -- now apparent in moisture-channel imagery over western CO and NM -- are forecast to merge today, reaching portions of KS, OK and north TX by 00Z. The combined perturbation then should eject northeastward across parts of the Mid-Mississippi Valley and Mid-South regions by 12Z tomorrow. As that occurs, 500-mb heights in the extensive field of southwesterlies over the Gulf Coast States will fall slightly, with a somewhat tightening gradient. At the surface, 11Z analysis showed a cold front extending from near TOL southwestward over southern IN, western parts of KY/TN, southwestern MS, between LCH-ARA, then over the northwestern Gulf to southeast of BRO. The front is expected to drift southeastward through the period, reaching eastern TN, northeastern/west-central AL, and south-central parts of MS/LA by 00Z. Substantial convective potential should remain prefrontal. ...North-central/northeastern Gulf Coast region... Isolate severe thunderstorms, with brief strong-severe gusts and/or potential for a couple tornadoes, are possible over the outlook area through this evening. Potential appears relatively maximized nearest the coast, where a few severe cells may move inland from the Gulf. Although the direct fields of large-scale ascent/DCVA related to the southern Rockies/Plains troughing will miss the region well to the northwest, the peripheral response discussed above should increase deep shear slightly over the region throughout the day. In the absence of a substantial, closer perturbation to elicit near-surface mass response, the persistent warm-advection/moisture-transport regime will continue, but with weakening and veering flow in the lower boundary layer after this morning. This should reduce hodograph size overall today, with the possible exception of localized boundary effects. The greatest low-level shear will be inland this morning, where stable to moist-adiabatic near-surface lapse rates are present, while instability should be most favorable over the Gulf, with some modified marine air spreading inland this evening and overnight when low-level wind profiles are more unidirectional than at present. The extensive area of overland clouds/precip is expected to persist for at lest a few more hours, and imparts considerable uncertainty/ conditionality on sufficiency of destabilization to support severe potential with inland extent. Unconditional severe probabilities accordingly decrease inland, and appear greatest over portions of southwestern AL and the FL Panhandle where 500-1000 J/kg MLCAPE and 40-450-kt effective-shear magnitudes should be present. ..Edwards/Kerr.. 12/02/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0643 AM CST Sat Dec 02 2023 Valid 021300Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NEAR THE COAST OF THE FLORIDA PANHANDLE AND A SMALL PART OF SOUTHWESTERN ALABAMA... ...SUMMARY... Isolated severe storms are possible over parts of the north-central/ northeastern Gulf Coast region. ...Synopsis... A mid/upper-level, synoptic-scale trough, with associated cyclonic flow traversed by several shortwave perturbations/vorticity lobes -- is expected to move eastward from its present position over the Rocky Mountain States. Leading/basal shortwave troughs -- now apparent in moisture-channel imagery over western CO and NM -- are forecast to merge today, reaching portions of KS, OK and north TX by 00Z. The combined perturbation then should eject northeastward across parts of the Mid-Mississippi Valley and Mid-South regions by 12Z tomorrow. As that occurs, 500-mb heights in the extensive field of southwesterlies over the Gulf Coast States will fall slightly, with a somewhat tightening gradient. At the surface, 11Z analysis showed a cold front extending from near TOL southwestward over southern IN, western parts of KY/TN, southwestern MS, between LCH-ARA, then over the northwestern Gulf to southeast of BRO. The front is expected to drift southeastward through the period, reaching eastern TN, northeastern/west-central AL, and south-central parts of MS/LA by 00Z. Substantial convective potential should remain prefrontal. ...North-central/northeastern Gulf Coast region... Isolate severe thunderstorms, with brief strong-severe gusts and/or potential for a couple tornadoes, are possible over the outlook area through this evening. Potential appears relatively maximized nearest the coast, where a few severe cells may move inland from the Gulf. Although the direct fields of large-scale ascent/DCVA related to the southern Rockies/Plains troughing will miss the region well to the northwest, the peripheral response discussed above should increase deep shear slightly over the region throughout the day. In the absence of a substantial, closer perturbation to elicit near-surface mass response, the persistent warm-advection/moisture-transport regime will continue, but with weakening and veering flow in the lower boundary layer after this morning. This should reduce hodograph size overall today, with the possible exception of localized boundary effects. The greatest low-level shear will be inland this morning, where stable to moist-adiabatic near-surface lapse rates are present, while instability should be most favorable over the Gulf, with some modified marine air spreading inland this evening and overnight when low-level wind profiles are more unidirectional than at present. The extensive area of overland clouds/precip is expected to persist for at lest a few more hours, and imparts considerable uncertainty/ conditionality on sufficiency of destabilization to support severe potential with inland extent. Unconditional severe probabilities accordingly decrease inland, and appear greatest over portions of southwestern AL and the FL Panhandle where 500-1000 J/kg MLCAPE and 40-450-kt effective-shear magnitudes should be present. ..Edwards/Kerr.. 12/02/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0643 AM CST Sat Dec 02 2023 Valid 021300Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NEAR THE COAST OF THE FLORIDA PANHANDLE AND A SMALL PART OF SOUTHWESTERN ALABAMA... ...SUMMARY... Isolated severe storms are possible over parts of the north-central/ northeastern Gulf Coast region. ...Synopsis... A mid/upper-level, synoptic-scale trough, with associated cyclonic flow traversed by several shortwave perturbations/vorticity lobes -- is expected to move eastward from its present position over the Rocky Mountain States. Leading/basal shortwave troughs -- now apparent in moisture-channel imagery over western CO and NM -- are forecast to merge today, reaching portions of KS, OK and north TX by 00Z. The combined perturbation then should eject northeastward across parts of the Mid-Mississippi Valley and Mid-South regions by 12Z tomorrow. As that occurs, 500-mb heights in the extensive field of southwesterlies over the Gulf Coast States will fall slightly, with a somewhat tightening gradient. At the surface, 11Z analysis showed a cold front extending from near TOL southwestward over southern IN, western parts of KY/TN, southwestern MS, between LCH-ARA, then over the northwestern Gulf to southeast of BRO. The front is expected to drift southeastward through the period, reaching eastern TN, northeastern/west-central AL, and south-central parts of MS/LA by 00Z. Substantial convective potential should remain prefrontal. ...North-central/northeastern Gulf Coast region... Isolate severe thunderstorms, with brief strong-severe gusts and/or potential for a couple tornadoes, are possible over the outlook area through this evening. Potential appears relatively maximized nearest the coast, where a few severe cells may move inland from the Gulf. Although the direct fields of large-scale ascent/DCVA related to the southern Rockies/Plains troughing will miss the region well to the northwest, the peripheral response discussed above should increase deep shear slightly over the region throughout the day. In the absence of a substantial, closer perturbation to elicit near-surface mass response, the persistent warm-advection/moisture-transport regime will continue, but with weakening and veering flow in the lower boundary layer after this morning. This should reduce hodograph size overall today, with the possible exception of localized boundary effects. The greatest low-level shear will be inland this morning, where stable to moist-adiabatic near-surface lapse rates are present, while instability should be most favorable over the Gulf, with some modified marine air spreading inland this evening and overnight when low-level wind profiles are more unidirectional than at present. The extensive area of overland clouds/precip is expected to persist for at lest a few more hours, and imparts considerable uncertainty/ conditionality on sufficiency of destabilization to support severe potential with inland extent. Unconditional severe probabilities accordingly decrease inland, and appear greatest over portions of southwestern AL and the FL Panhandle where 500-1000 J/kg MLCAPE and 40-450-kt effective-shear magnitudes should be present. ..Edwards/Kerr.. 12/02/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0643 AM CST Sat Dec 02 2023 Valid 021300Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NEAR THE COAST OF THE FLORIDA PANHANDLE AND A SMALL PART OF SOUTHWESTERN ALABAMA... ...SUMMARY... Isolated severe storms are possible over parts of the north-central/ northeastern Gulf Coast region. ...Synopsis... A mid/upper-level, synoptic-scale trough, with associated cyclonic flow traversed by several shortwave perturbations/vorticity lobes -- is expected to move eastward from its present position over the Rocky Mountain States. Leading/basal shortwave troughs -- now apparent in moisture-channel imagery over western CO and NM -- are forecast to merge today, reaching portions of KS, OK and north TX by 00Z. The combined perturbation then should eject northeastward across parts of the Mid-Mississippi Valley and Mid-South regions by 12Z tomorrow. As that occurs, 500-mb heights in the extensive field of southwesterlies over the Gulf Coast States will fall slightly, with a somewhat tightening gradient. At the surface, 11Z analysis showed a cold front extending from near TOL southwestward over southern IN, western parts of KY/TN, southwestern MS, between LCH-ARA, then over the northwestern Gulf to southeast of BRO. The front is expected to drift southeastward through the period, reaching eastern TN, northeastern/west-central AL, and south-central parts of MS/LA by 00Z. Substantial convective potential should remain prefrontal. ...North-central/northeastern Gulf Coast region... Isolate severe thunderstorms, with brief strong-severe gusts and/or potential for a couple tornadoes, are possible over the outlook area through this evening. Potential appears relatively maximized nearest the coast, where a few severe cells may move inland from the Gulf. Although the direct fields of large-scale ascent/DCVA related to the southern Rockies/Plains troughing will miss the region well to the northwest, the peripheral response discussed above should increase deep shear slightly over the region throughout the day. In the absence of a substantial, closer perturbation to elicit near-surface mass response, the persistent warm-advection/moisture-transport regime will continue, but with weakening and veering flow in the lower boundary layer after this morning. This should reduce hodograph size overall today, with the possible exception of localized boundary effects. The greatest low-level shear will be inland this morning, where stable to moist-adiabatic near-surface lapse rates are present, while instability should be most favorable over the Gulf, with some modified marine air spreading inland this evening and overnight when low-level wind profiles are more unidirectional than at present. The extensive area of overland clouds/precip is expected to persist for at lest a few more hours, and imparts considerable uncertainty/ conditionality on sufficiency of destabilization to support severe potential with inland extent. Unconditional severe probabilities accordingly decrease inland, and appear greatest over portions of southwestern AL and the FL Panhandle where 500-1000 J/kg MLCAPE and 40-450-kt effective-shear magnitudes should be present. ..Edwards/Kerr.. 12/02/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0643 AM CST Sat Dec 02 2023 Valid 021300Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NEAR THE COAST OF THE FLORIDA PANHANDLE AND A SMALL PART OF SOUTHWESTERN ALABAMA... ...SUMMARY... Isolated severe storms are possible over parts of the north-central/ northeastern Gulf Coast region. ...Synopsis... A mid/upper-level, synoptic-scale trough, with associated cyclonic flow traversed by several shortwave perturbations/vorticity lobes -- is expected to move eastward from its present position over the Rocky Mountain States. Leading/basal shortwave troughs -- now apparent in moisture-channel imagery over western CO and NM -- are forecast to merge today, reaching portions of KS, OK and north TX by 00Z. The combined perturbation then should eject northeastward across parts of the Mid-Mississippi Valley and Mid-South regions by 12Z tomorrow. As that occurs, 500-mb heights in the extensive field of southwesterlies over the Gulf Coast States will fall slightly, with a somewhat tightening gradient. At the surface, 11Z analysis showed a cold front extending from near TOL southwestward over southern IN, western parts of KY/TN, southwestern MS, between LCH-ARA, then over the northwestern Gulf to southeast of BRO. The front is expected to drift southeastward through the period, reaching eastern TN, northeastern/west-central AL, and south-central parts of MS/LA by 00Z. Substantial convective potential should remain prefrontal. ...North-central/northeastern Gulf Coast region... Isolate severe thunderstorms, with brief strong-severe gusts and/or potential for a couple tornadoes, are possible over the outlook area through this evening. Potential appears relatively maximized nearest the coast, where a few severe cells may move inland from the Gulf. Although the direct fields of large-scale ascent/DCVA related to the southern Rockies/Plains troughing will miss the region well to the northwest, the peripheral response discussed above should increase deep shear slightly over the region throughout the day. In the absence of a substantial, closer perturbation to elicit near-surface mass response, the persistent warm-advection/moisture-transport regime will continue, but with weakening and veering flow in the lower boundary layer after this morning. This should reduce hodograph size overall today, with the possible exception of localized boundary effects. The greatest low-level shear will be inland this morning, where stable to moist-adiabatic near-surface lapse rates are present, while instability should be most favorable over the Gulf, with some modified marine air spreading inland this evening and overnight when low-level wind profiles are more unidirectional than at present. The extensive area of overland clouds/precip is expected to persist for at lest a few more hours, and imparts considerable uncertainty/ conditionality on sufficiency of destabilization to support severe potential with inland extent. Unconditional severe probabilities accordingly decrease inland, and appear greatest over portions of southwestern AL and the FL Panhandle where 500-1000 J/kg MLCAPE and 40-450-kt effective-shear magnitudes should be present. ..Edwards/Kerr.. 12/02/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0643 AM CST Sat Dec 02 2023 Valid 021300Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NEAR THE COAST OF THE FLORIDA PANHANDLE AND A SMALL PART OF SOUTHWESTERN ALABAMA... ...SUMMARY... Isolated severe storms are possible over parts of the north-central/ northeastern Gulf Coast region. ...Synopsis... A mid/upper-level, synoptic-scale trough, with associated cyclonic flow traversed by several shortwave perturbations/vorticity lobes -- is expected to move eastward from its present position over the Rocky Mountain States. Leading/basal shortwave troughs -- now apparent in moisture-channel imagery over western CO and NM -- are forecast to merge today, reaching portions of KS, OK and north TX by 00Z. The combined perturbation then should eject northeastward across parts of the Mid-Mississippi Valley and Mid-South regions by 12Z tomorrow. As that occurs, 500-mb heights in the extensive field of southwesterlies over the Gulf Coast States will fall slightly, with a somewhat tightening gradient. At the surface, 11Z analysis showed a cold front extending from near TOL southwestward over southern IN, western parts of KY/TN, southwestern MS, between LCH-ARA, then over the northwestern Gulf to southeast of BRO. The front is expected to drift southeastward through the period, reaching eastern TN, northeastern/west-central AL, and south-central parts of MS/LA by 00Z. Substantial convective potential should remain prefrontal. ...North-central/northeastern Gulf Coast region... Isolate severe thunderstorms, with brief strong-severe gusts and/or potential for a couple tornadoes, are possible over the outlook area through this evening. Potential appears relatively maximized nearest the coast, where a few severe cells may move inland from the Gulf. Although the direct fields of large-scale ascent/DCVA related to the southern Rockies/Plains troughing will miss the region well to the northwest, the peripheral response discussed above should increase deep shear slightly over the region throughout the day. In the absence of a substantial, closer perturbation to elicit near-surface mass response, the persistent warm-advection/moisture-transport regime will continue, but with weakening and veering flow in the lower boundary layer after this morning. This should reduce hodograph size overall today, with the possible exception of localized boundary effects. The greatest low-level shear will be inland this morning, where stable to moist-adiabatic near-surface lapse rates are present, while instability should be most favorable over the Gulf, with some modified marine air spreading inland this evening and overnight when low-level wind profiles are more unidirectional than at present. The extensive area of overland clouds/precip is expected to persist for at lest a few more hours, and imparts considerable uncertainty/ conditionality on sufficiency of destabilization to support severe potential with inland extent. Unconditional severe probabilities accordingly decrease inland, and appear greatest over portions of southwestern AL and the FL Panhandle where 500-1000 J/kg MLCAPE and 40-450-kt effective-shear magnitudes should be present. ..Edwards/Kerr.. 12/02/2023 Read more

MD 2301 CONCERNING TORNADO WATCH 713... FOR SOUTHEASTERN LOUISIANA...SOUTHERN MISSISSIPPI...SOUTHWESTERN ALABAMA AND THE WESTERN FLORIDA PANHANDLE
Mesoscale Discussion 2301 NWS Storm Prediction Center Norman OK 0321 AM CST Sat Dec 02 2023 Areas affected...southeastern Louisiana...southern Mississippi...southwestern Alabama and the western Florida Panhandle Concerning...Tornado Watch 713... Valid 020921Z - 021115Z The severe weather threat for Tornado Watch 713 continues. SUMMARY...Scattered thunderstorm activity will continue across the region into and beyond daybreak. While the risk for severe weather may not be completely negligible, it appears low enough that a new severe weather watch will not be needed, at least in the near term. DISCUSSION...Downstream of mid-level troughing still progressing across the southern Rockies, and on the northern periphery of mid-level subtropical ridging centered over the Caribbean, scattered thunderstorm activity continues to slowly develop east-northeastward near and across coastal areas from southern Louisiana into the western Florida Panhandle. This appears supported by forcing for ascent driven by lower/mid-tropospheric warm advection, beneath broadly difluent upper flow, with convection generally rooted above near-surface lapse rates ranging from stable to perhaps approaching moist adiabatic. Modest mid-level lapse rates may be allowing for most unstable CAPE ranging from 500-1000 J/kg, in the presence of wind fields/shear potentially supportive of supercells. However, with little change in the near-surface thermodynamic profiles forecast through at least mid-morning, an appreciable increase in severe thunderstorm potential across and inland of coastal areas appears unlikely anytime soon. ..Kerr.. 12/02/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TAE...MOB...JAN...LIX...LCH... LAT...LON 30229182 31238943 30898788 30948601 30128556 29418623 28978764 29418924 29239100 29349241 30229182 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0343 AM CST Sat Dec 02 2023 Valid 051200Z - 101200Z ...DISCUSSION... ...Tuesday/Day 4 to Thursday/Day 6... A mid-level trough is forecast to move into the mid Mississippi Valley on Tuesday, and then to the Atlantic Coast by Wednesday. An upper-level ridge is forecast to move into the central states during the mid-week. As a result, a relatively dry airmass should remain in place over much of the continental United States making conditions unfavorable for thunderstorms in most areas. ...Friday/Day 7 and Saturday/Day 8... On Friday, moisture return is forecast across the Southern Plains and Ark-La-Tex, as a mid-level trough moves into the western U.S. A closed-off low, associated with this system, is forecast to develop on Saturday across the Four Corners region. Ahead of the low, thunderstorm development could occur in parts of the southern Plains on Saturday. However, predictability remains low at this extended range, mainly due to uncertainty concerning instability and system timing. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0343 AM CST Sat Dec 02 2023 Valid 051200Z - 101200Z ...DISCUSSION... ...Tuesday/Day 4 to Thursday/Day 6... A mid-level trough is forecast to move into the mid Mississippi Valley on Tuesday, and then to the Atlantic Coast by Wednesday. An upper-level ridge is forecast to move into the central states during the mid-week. As a result, a relatively dry airmass should remain in place over much of the continental United States making conditions unfavorable for thunderstorms in most areas. ...Friday/Day 7 and Saturday/Day 8... On Friday, moisture return is forecast across the Southern Plains and Ark-La-Tex, as a mid-level trough moves into the western U.S. A closed-off low, associated with this system, is forecast to develop on Saturday across the Four Corners region. Ahead of the low, thunderstorm development could occur in parts of the southern Plains on Saturday. However, predictability remains low at this extended range, mainly due to uncertainty concerning instability and system timing. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0343 AM CST Sat Dec 02 2023 Valid 051200Z - 101200Z ...DISCUSSION... ...Tuesday/Day 4 to Thursday/Day 6... A mid-level trough is forecast to move into the mid Mississippi Valley on Tuesday, and then to the Atlantic Coast by Wednesday. An upper-level ridge is forecast to move into the central states during the mid-week. As a result, a relatively dry airmass should remain in place over much of the continental United States making conditions unfavorable for thunderstorms in most areas. ...Friday/Day 7 and Saturday/Day 8... On Friday, moisture return is forecast across the Southern Plains and Ark-La-Tex, as a mid-level trough moves into the western U.S. A closed-off low, associated with this system, is forecast to develop on Saturday across the Four Corners region. Ahead of the low, thunderstorm development could occur in parts of the southern Plains on Saturday. However, predictability remains low at this extended range, mainly due to uncertainty concerning instability and system timing. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0343 AM CST Sat Dec 02 2023 Valid 051200Z - 101200Z ...DISCUSSION... ...Tuesday/Day 4 to Thursday/Day 6... A mid-level trough is forecast to move into the mid Mississippi Valley on Tuesday, and then to the Atlantic Coast by Wednesday. An upper-level ridge is forecast to move into the central states during the mid-week. As a result, a relatively dry airmass should remain in place over much of the continental United States making conditions unfavorable for thunderstorms in most areas. ...Friday/Day 7 and Saturday/Day 8... On Friday, moisture return is forecast across the Southern Plains and Ark-La-Tex, as a mid-level trough moves into the western U.S. A closed-off low, associated with this system, is forecast to develop on Saturday across the Four Corners region. Ahead of the low, thunderstorm development could occur in parts of the southern Plains on Saturday. However, predictability remains low at this extended range, mainly due to uncertainty concerning instability and system timing. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0343 AM CST Sat Dec 02 2023 Valid 051200Z - 101200Z ...DISCUSSION... ...Tuesday/Day 4 to Thursday/Day 6... A mid-level trough is forecast to move into the mid Mississippi Valley on Tuesday, and then to the Atlantic Coast by Wednesday. An upper-level ridge is forecast to move into the central states during the mid-week. As a result, a relatively dry airmass should remain in place over much of the continental United States making conditions unfavorable for thunderstorms in most areas. ...Friday/Day 7 and Saturday/Day 8... On Friday, moisture return is forecast across the Southern Plains and Ark-La-Tex, as a mid-level trough moves into the western U.S. A closed-off low, associated with this system, is forecast to develop on Saturday across the Four Corners region. Ahead of the low, thunderstorm development could occur in parts of the southern Plains on Saturday. However, predictability remains low at this extended range, mainly due to uncertainty concerning instability and system timing. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0343 AM CST Sat Dec 02 2023 Valid 051200Z - 101200Z ...DISCUSSION... ...Tuesday/Day 4 to Thursday/Day 6... A mid-level trough is forecast to move into the mid Mississippi Valley on Tuesday, and then to the Atlantic Coast by Wednesday. An upper-level ridge is forecast to move into the central states during the mid-week. As a result, a relatively dry airmass should remain in place over much of the continental United States making conditions unfavorable for thunderstorms in most areas. ...Friday/Day 7 and Saturday/Day 8... On Friday, moisture return is forecast across the Southern Plains and Ark-La-Tex, as a mid-level trough moves into the western U.S. A closed-off low, associated with this system, is forecast to develop on Saturday across the Four Corners region. Ahead of the low, thunderstorm development could occur in parts of the southern Plains on Saturday. However, predictability remains low at this extended range, mainly due to uncertainty concerning instability and system timing. Read more