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SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0644 AM CST Wed Nov 27 2024 Valid 271300Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL MISSISSIPPI TO CENTRAL AND NORTHERN ALABAMA...AND PARTS OF THE WESTERN/CENTRAL FLORIDA PANHANDLE TO SOUTHWESTERN GEORGIA... ...SUMMARY... Isolated strong to severe storms are possible late tonight into early Thanksgiving morning, over central Mississippi to central and northern Alabama, and parts of the western/central Florida Panhandle to southwestern Georgia. ...Synopsis... A progressive, nearly zonal middle/upper-level pattern over much of the CONUS will become more cyclonically curved east of the Rockies through the period. Contributing to this will be a positively tilted shortwave trough -- evident in moisture-channel imagery from central WY across northern parts of UT/NV. This perturbation should move rapidly across the central Rockies today, reaching southern parts of KS and CO by 00Z. The trough then should pivot east- northeastward and elongate, reaching the Ohio Valley and Ozarks by 12Z tomorrow. 11Z surface analysis showed an area of low pressure over the northern TX Panhandle into northeastern NM, along and south of a cold front extending into the Sangre de Cristos between RTN-TAD. By 00Z, the low should consolidate and reach central or west-central AR, with cold front southwestward across north-central and west- central TX to southeastern NM. The main low should redevelop to the northeast over KY tonight, then move to a 12Z position roughly near MGW, with cold front then extending to near the NC/TN line, northern AL, south-central MS, southeastern LA, shelf waters off the middle/ upper TX Coast, to deep south TX. ...MS/AL... Widely scattered to scattered thunderstorms are expected to develop near the cold front overnight -- most likely after 06Z -- with marginal potential for a tornado, isolated damaging winds or severe hail. Despite the veered (southwesterly) surface flow ahead of the front, a 40-50-kt west-southwesterly LLJ should contribute to long low- level hodographs with some curvature. That will foster 200-300 J/kg effective and 0-1-km SRH values (locally higher), amidst 45-55-kt effective-shear magnitudes and a narrow, front-parallel plume of 500-1000 J/kg MLCAPE. However, with the veering prefrontal flow, lift along the front will be compromised to some extent, causing uncertainty on storm coverage. Also, weak boundary-layer lapse rates -- characteristic of this time of day in marginal-moisture scenarios -- may yield long time windows for convective deepening, potentially limiting storm strength at maturity if activity merges with other precip or moves into weaker instability, as progged. Given these concerns, the threat continues to appear limited but nonzero in nature, and has been removed from previous northwestern areas where it now appears frontal passage will precede substantial deep development. ...Coastal FL Panhandle to southwestern GA... Isolated to widely scattered thunderstorms are possible late tonight, with a low-end but not negligible tornado and strong/ severe-gust threat. Development would be concentrated near a maximum in boundary-layer lift accompanying southwest/northeast-oriented, low-level, prefrontal confluence axis, undergoing theta-e advection from favorably modifying maritime air on the north rim of the Loop Current. Modified forecast soundings show progressive lift and erosion of a stable/capping layer from about 650-800 mb, located beneath 500-1000 J/kg MLCAPE, as warm advection persists below that stable layer and lift continues along the kinematic boundary. This may support development of a few thunderstorms after 06Z, with enough low-level and deep shear on the east side of the boundary (where surface winds will be relatively backed) to support supercell potential, amidst roughly 40 kt effective-shear magnitudes and 100-150 J/kg of 0-1-km SRH. ..Edwards/Leitman.. 11/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0644 AM CST Wed Nov 27 2024 Valid 271300Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL MISSISSIPPI TO CENTRAL AND NORTHERN ALABAMA...AND PARTS OF THE WESTERN/CENTRAL FLORIDA PANHANDLE TO SOUTHWESTERN GEORGIA... ...SUMMARY... Isolated strong to severe storms are possible late tonight into early Thanksgiving morning, over central Mississippi to central and northern Alabama, and parts of the western/central Florida Panhandle to southwestern Georgia. ...Synopsis... A progressive, nearly zonal middle/upper-level pattern over much of the CONUS will become more cyclonically curved east of the Rockies through the period. Contributing to this will be a positively tilted shortwave trough -- evident in moisture-channel imagery from central WY across northern parts of UT/NV. This perturbation should move rapidly across the central Rockies today, reaching southern parts of KS and CO by 00Z. The trough then should pivot east- northeastward and elongate, reaching the Ohio Valley and Ozarks by 12Z tomorrow. 11Z surface analysis showed an area of low pressure over the northern TX Panhandle into northeastern NM, along and south of a cold front extending into the Sangre de Cristos between RTN-TAD. By 00Z, the low should consolidate and reach central or west-central AR, with cold front southwestward across north-central and west- central TX to southeastern NM. The main low should redevelop to the northeast over KY tonight, then move to a 12Z position roughly near MGW, with cold front then extending to near the NC/TN line, northern AL, south-central MS, southeastern LA, shelf waters off the middle/ upper TX Coast, to deep south TX. ...MS/AL... Widely scattered to scattered thunderstorms are expected to develop near the cold front overnight -- most likely after 06Z -- with marginal potential for a tornado, isolated damaging winds or severe hail. Despite the veered (southwesterly) surface flow ahead of the front, a 40-50-kt west-southwesterly LLJ should contribute to long low- level hodographs with some curvature. That will foster 200-300 J/kg effective and 0-1-km SRH values (locally higher), amidst 45-55-kt effective-shear magnitudes and a narrow, front-parallel plume of 500-1000 J/kg MLCAPE. However, with the veering prefrontal flow, lift along the front will be compromised to some extent, causing uncertainty on storm coverage. Also, weak boundary-layer lapse rates -- characteristic of this time of day in marginal-moisture scenarios -- may yield long time windows for convective deepening, potentially limiting storm strength at maturity if activity merges with other precip or moves into weaker instability, as progged. Given these concerns, the threat continues to appear limited but nonzero in nature, and has been removed from previous northwestern areas where it now appears frontal passage will precede substantial deep development. ...Coastal FL Panhandle to southwestern GA... Isolated to widely scattered thunderstorms are possible late tonight, with a low-end but not negligible tornado and strong/ severe-gust threat. Development would be concentrated near a maximum in boundary-layer lift accompanying southwest/northeast-oriented, low-level, prefrontal confluence axis, undergoing theta-e advection from favorably modifying maritime air on the north rim of the Loop Current. Modified forecast soundings show progressive lift and erosion of a stable/capping layer from about 650-800 mb, located beneath 500-1000 J/kg MLCAPE, as warm advection persists below that stable layer and lift continues along the kinematic boundary. This may support development of a few thunderstorms after 06Z, with enough low-level and deep shear on the east side of the boundary (where surface winds will be relatively backed) to support supercell potential, amidst roughly 40 kt effective-shear magnitudes and 100-150 J/kg of 0-1-km SRH. ..Edwards/Leitman.. 11/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0644 AM CST Wed Nov 27 2024 Valid 271300Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL MISSISSIPPI TO CENTRAL AND NORTHERN ALABAMA...AND PARTS OF THE WESTERN/CENTRAL FLORIDA PANHANDLE TO SOUTHWESTERN GEORGIA... ...SUMMARY... Isolated strong to severe storms are possible late tonight into early Thanksgiving morning, over central Mississippi to central and northern Alabama, and parts of the western/central Florida Panhandle to southwestern Georgia. ...Synopsis... A progressive, nearly zonal middle/upper-level pattern over much of the CONUS will become more cyclonically curved east of the Rockies through the period. Contributing to this will be a positively tilted shortwave trough -- evident in moisture-channel imagery from central WY across northern parts of UT/NV. This perturbation should move rapidly across the central Rockies today, reaching southern parts of KS and CO by 00Z. The trough then should pivot east- northeastward and elongate, reaching the Ohio Valley and Ozarks by 12Z tomorrow. 11Z surface analysis showed an area of low pressure over the northern TX Panhandle into northeastern NM, along and south of a cold front extending into the Sangre de Cristos between RTN-TAD. By 00Z, the low should consolidate and reach central or west-central AR, with cold front southwestward across north-central and west- central TX to southeastern NM. The main low should redevelop to the northeast over KY tonight, then move to a 12Z position roughly near MGW, with cold front then extending to near the NC/TN line, northern AL, south-central MS, southeastern LA, shelf waters off the middle/ upper TX Coast, to deep south TX. ...MS/AL... Widely scattered to scattered thunderstorms are expected to develop near the cold front overnight -- most likely after 06Z -- with marginal potential for a tornado, isolated damaging winds or severe hail. Despite the veered (southwesterly) surface flow ahead of the front, a 40-50-kt west-southwesterly LLJ should contribute to long low- level hodographs with some curvature. That will foster 200-300 J/kg effective and 0-1-km SRH values (locally higher), amidst 45-55-kt effective-shear magnitudes and a narrow, front-parallel plume of 500-1000 J/kg MLCAPE. However, with the veering prefrontal flow, lift along the front will be compromised to some extent, causing uncertainty on storm coverage. Also, weak boundary-layer lapse rates -- characteristic of this time of day in marginal-moisture scenarios -- may yield long time windows for convective deepening, potentially limiting storm strength at maturity if activity merges with other precip or moves into weaker instability, as progged. Given these concerns, the threat continues to appear limited but nonzero in nature, and has been removed from previous northwestern areas where it now appears frontal passage will precede substantial deep development. ...Coastal FL Panhandle to southwestern GA... Isolated to widely scattered thunderstorms are possible late tonight, with a low-end but not negligible tornado and strong/ severe-gust threat. Development would be concentrated near a maximum in boundary-layer lift accompanying southwest/northeast-oriented, low-level, prefrontal confluence axis, undergoing theta-e advection from favorably modifying maritime air on the north rim of the Loop Current. Modified forecast soundings show progressive lift and erosion of a stable/capping layer from about 650-800 mb, located beneath 500-1000 J/kg MLCAPE, as warm advection persists below that stable layer and lift continues along the kinematic boundary. This may support development of a few thunderstorms after 06Z, with enough low-level and deep shear on the east side of the boundary (where surface winds will be relatively backed) to support supercell potential, amidst roughly 40 kt effective-shear magnitudes and 100-150 J/kg of 0-1-km SRH. ..Edwards/Leitman.. 11/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0644 AM CST Wed Nov 27 2024 Valid 271300Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL MISSISSIPPI TO CENTRAL AND NORTHERN ALABAMA...AND PARTS OF THE WESTERN/CENTRAL FLORIDA PANHANDLE TO SOUTHWESTERN GEORGIA... ...SUMMARY... Isolated strong to severe storms are possible late tonight into early Thanksgiving morning, over central Mississippi to central and northern Alabama, and parts of the western/central Florida Panhandle to southwestern Georgia. ...Synopsis... A progressive, nearly zonal middle/upper-level pattern over much of the CONUS will become more cyclonically curved east of the Rockies through the period. Contributing to this will be a positively tilted shortwave trough -- evident in moisture-channel imagery from central WY across northern parts of UT/NV. This perturbation should move rapidly across the central Rockies today, reaching southern parts of KS and CO by 00Z. The trough then should pivot east- northeastward and elongate, reaching the Ohio Valley and Ozarks by 12Z tomorrow. 11Z surface analysis showed an area of low pressure over the northern TX Panhandle into northeastern NM, along and south of a cold front extending into the Sangre de Cristos between RTN-TAD. By 00Z, the low should consolidate and reach central or west-central AR, with cold front southwestward across north-central and west- central TX to southeastern NM. The main low should redevelop to the northeast over KY tonight, then move to a 12Z position roughly near MGW, with cold front then extending to near the NC/TN line, northern AL, south-central MS, southeastern LA, shelf waters off the middle/ upper TX Coast, to deep south TX. ...MS/AL... Widely scattered to scattered thunderstorms are expected to develop near the cold front overnight -- most likely after 06Z -- with marginal potential for a tornado, isolated damaging winds or severe hail. Despite the veered (southwesterly) surface flow ahead of the front, a 40-50-kt west-southwesterly LLJ should contribute to long low- level hodographs with some curvature. That will foster 200-300 J/kg effective and 0-1-km SRH values (locally higher), amidst 45-55-kt effective-shear magnitudes and a narrow, front-parallel plume of 500-1000 J/kg MLCAPE. However, with the veering prefrontal flow, lift along the front will be compromised to some extent, causing uncertainty on storm coverage. Also, weak boundary-layer lapse rates -- characteristic of this time of day in marginal-moisture scenarios -- may yield long time windows for convective deepening, potentially limiting storm strength at maturity if activity merges with other precip or moves into weaker instability, as progged. Given these concerns, the threat continues to appear limited but nonzero in nature, and has been removed from previous northwestern areas where it now appears frontal passage will precede substantial deep development. ...Coastal FL Panhandle to southwestern GA... Isolated to widely scattered thunderstorms are possible late tonight, with a low-end but not negligible tornado and strong/ severe-gust threat. Development would be concentrated near a maximum in boundary-layer lift accompanying southwest/northeast-oriented, low-level, prefrontal confluence axis, undergoing theta-e advection from favorably modifying maritime air on the north rim of the Loop Current. Modified forecast soundings show progressive lift and erosion of a stable/capping layer from about 650-800 mb, located beneath 500-1000 J/kg MLCAPE, as warm advection persists below that stable layer and lift continues along the kinematic boundary. This may support development of a few thunderstorms after 06Z, with enough low-level and deep shear on the east side of the boundary (where surface winds will be relatively backed) to support supercell potential, amidst roughly 40 kt effective-shear magnitudes and 100-150 J/kg of 0-1-km SRH. ..Edwards/Leitman.. 11/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0644 AM CST Wed Nov 27 2024 Valid 271300Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL MISSISSIPPI TO CENTRAL AND NORTHERN ALABAMA...AND PARTS OF THE WESTERN/CENTRAL FLORIDA PANHANDLE TO SOUTHWESTERN GEORGIA... ...SUMMARY... Isolated strong to severe storms are possible late tonight into early Thanksgiving morning, over central Mississippi to central and northern Alabama, and parts of the western/central Florida Panhandle to southwestern Georgia. ...Synopsis... A progressive, nearly zonal middle/upper-level pattern over much of the CONUS will become more cyclonically curved east of the Rockies through the period. Contributing to this will be a positively tilted shortwave trough -- evident in moisture-channel imagery from central WY across northern parts of UT/NV. This perturbation should move rapidly across the central Rockies today, reaching southern parts of KS and CO by 00Z. The trough then should pivot east- northeastward and elongate, reaching the Ohio Valley and Ozarks by 12Z tomorrow. 11Z surface analysis showed an area of low pressure over the northern TX Panhandle into northeastern NM, along and south of a cold front extending into the Sangre de Cristos between RTN-TAD. By 00Z, the low should consolidate and reach central or west-central AR, with cold front southwestward across north-central and west- central TX to southeastern NM. The main low should redevelop to the northeast over KY tonight, then move to a 12Z position roughly near MGW, with cold front then extending to near the NC/TN line, northern AL, south-central MS, southeastern LA, shelf waters off the middle/ upper TX Coast, to deep south TX. ...MS/AL... Widely scattered to scattered thunderstorms are expected to develop near the cold front overnight -- most likely after 06Z -- with marginal potential for a tornado, isolated damaging winds or severe hail. Despite the veered (southwesterly) surface flow ahead of the front, a 40-50-kt west-southwesterly LLJ should contribute to long low- level hodographs with some curvature. That will foster 200-300 J/kg effective and 0-1-km SRH values (locally higher), amidst 45-55-kt effective-shear magnitudes and a narrow, front-parallel plume of 500-1000 J/kg MLCAPE. However, with the veering prefrontal flow, lift along the front will be compromised to some extent, causing uncertainty on storm coverage. Also, weak boundary-layer lapse rates -- characteristic of this time of day in marginal-moisture scenarios -- may yield long time windows for convective deepening, potentially limiting storm strength at maturity if activity merges with other precip or moves into weaker instability, as progged. Given these concerns, the threat continues to appear limited but nonzero in nature, and has been removed from previous northwestern areas where it now appears frontal passage will precede substantial deep development. ...Coastal FL Panhandle to southwestern GA... Isolated to widely scattered thunderstorms are possible late tonight, with a low-end but not negligible tornado and strong/ severe-gust threat. Development would be concentrated near a maximum in boundary-layer lift accompanying southwest/northeast-oriented, low-level, prefrontal confluence axis, undergoing theta-e advection from favorably modifying maritime air on the north rim of the Loop Current. Modified forecast soundings show progressive lift and erosion of a stable/capping layer from about 650-800 mb, located beneath 500-1000 J/kg MLCAPE, as warm advection persists below that stable layer and lift continues along the kinematic boundary. This may support development of a few thunderstorms after 06Z, with enough low-level and deep shear on the east side of the boundary (where surface winds will be relatively backed) to support supercell potential, amidst roughly 40 kt effective-shear magnitudes and 100-150 J/kg of 0-1-km SRH. ..Edwards/Leitman.. 11/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0644 AM CST Wed Nov 27 2024 Valid 271300Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL MISSISSIPPI TO CENTRAL AND NORTHERN ALABAMA...AND PARTS OF THE WESTERN/CENTRAL FLORIDA PANHANDLE TO SOUTHWESTERN GEORGIA... ...SUMMARY... Isolated strong to severe storms are possible late tonight into early Thanksgiving morning, over central Mississippi to central and northern Alabama, and parts of the western/central Florida Panhandle to southwestern Georgia. ...Synopsis... A progressive, nearly zonal middle/upper-level pattern over much of the CONUS will become more cyclonically curved east of the Rockies through the period. Contributing to this will be a positively tilted shortwave trough -- evident in moisture-channel imagery from central WY across northern parts of UT/NV. This perturbation should move rapidly across the central Rockies today, reaching southern parts of KS and CO by 00Z. The trough then should pivot east- northeastward and elongate, reaching the Ohio Valley and Ozarks by 12Z tomorrow. 11Z surface analysis showed an area of low pressure over the northern TX Panhandle into northeastern NM, along and south of a cold front extending into the Sangre de Cristos between RTN-TAD. By 00Z, the low should consolidate and reach central or west-central AR, with cold front southwestward across north-central and west- central TX to southeastern NM. The main low should redevelop to the northeast over KY tonight, then move to a 12Z position roughly near MGW, with cold front then extending to near the NC/TN line, northern AL, south-central MS, southeastern LA, shelf waters off the middle/ upper TX Coast, to deep south TX. ...MS/AL... Widely scattered to scattered thunderstorms are expected to develop near the cold front overnight -- most likely after 06Z -- with marginal potential for a tornado, isolated damaging winds or severe hail. Despite the veered (southwesterly) surface flow ahead of the front, a 40-50-kt west-southwesterly LLJ should contribute to long low- level hodographs with some curvature. That will foster 200-300 J/kg effective and 0-1-km SRH values (locally higher), amidst 45-55-kt effective-shear magnitudes and a narrow, front-parallel plume of 500-1000 J/kg MLCAPE. However, with the veering prefrontal flow, lift along the front will be compromised to some extent, causing uncertainty on storm coverage. Also, weak boundary-layer lapse rates -- characteristic of this time of day in marginal-moisture scenarios -- may yield long time windows for convective deepening, potentially limiting storm strength at maturity if activity merges with other precip or moves into weaker instability, as progged. Given these concerns, the threat continues to appear limited but nonzero in nature, and has been removed from previous northwestern areas where it now appears frontal passage will precede substantial deep development. ...Coastal FL Panhandle to southwestern GA... Isolated to widely scattered thunderstorms are possible late tonight, with a low-end but not negligible tornado and strong/ severe-gust threat. Development would be concentrated near a maximum in boundary-layer lift accompanying southwest/northeast-oriented, low-level, prefrontal confluence axis, undergoing theta-e advection from favorably modifying maritime air on the north rim of the Loop Current. Modified forecast soundings show progressive lift and erosion of a stable/capping layer from about 650-800 mb, located beneath 500-1000 J/kg MLCAPE, as warm advection persists below that stable layer and lift continues along the kinematic boundary. This may support development of a few thunderstorms after 06Z, with enough low-level and deep shear on the east side of the boundary (where surface winds will be relatively backed) to support supercell potential, amidst roughly 40 kt effective-shear magnitudes and 100-150 J/kg of 0-1-km SRH. ..Edwards/Leitman.. 11/27/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0300 AM CST Wed Nov 27 2024 Valid 301200Z - 051200Z ...DISCUSSION... Severe-thunderstorm potential still appears low through the extended range. An upper-level trough is expected to persist across the eastern CONUS through the period, as multiple reinforcing shortwaves move southeastward from Canada. A surface ridge covering much of the central/eastern CONUS will inhibit low-level moisture return through most of the extended range. Guidance suggests potential for the surface ridge to eventually shift eastward by D7/Tuesday into D8/Wednesday, allowing for some moisture return into parts of Texas. This could lead to an increase in thunderstorm activity, but the displacement between stronger deep-layer flow/shear and any appreciable surface-based instability currently appears too large to support organized severe potential through early next week. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0300 AM CST Wed Nov 27 2024 Valid 301200Z - 051200Z ...DISCUSSION... Severe-thunderstorm potential still appears low through the extended range. An upper-level trough is expected to persist across the eastern CONUS through the period, as multiple reinforcing shortwaves move southeastward from Canada. A surface ridge covering much of the central/eastern CONUS will inhibit low-level moisture return through most of the extended range. Guidance suggests potential for the surface ridge to eventually shift eastward by D7/Tuesday into D8/Wednesday, allowing for some moisture return into parts of Texas. This could lead to an increase in thunderstorm activity, but the displacement between stronger deep-layer flow/shear and any appreciable surface-based instability currently appears too large to support organized severe potential through early next week. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0300 AM CST Wed Nov 27 2024 Valid 301200Z - 051200Z ...DISCUSSION... Severe-thunderstorm potential still appears low through the extended range. An upper-level trough is expected to persist across the eastern CONUS through the period, as multiple reinforcing shortwaves move southeastward from Canada. A surface ridge covering much of the central/eastern CONUS will inhibit low-level moisture return through most of the extended range. Guidance suggests potential for the surface ridge to eventually shift eastward by D7/Tuesday into D8/Wednesday, allowing for some moisture return into parts of Texas. This could lead to an increase in thunderstorm activity, but the displacement between stronger deep-layer flow/shear and any appreciable surface-based instability currently appears too large to support organized severe potential through early next week. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0300 AM CST Wed Nov 27 2024 Valid 301200Z - 051200Z ...DISCUSSION... Severe-thunderstorm potential still appears low through the extended range. An upper-level trough is expected to persist across the eastern CONUS through the period, as multiple reinforcing shortwaves move southeastward from Canada. A surface ridge covering much of the central/eastern CONUS will inhibit low-level moisture return through most of the extended range. Guidance suggests potential for the surface ridge to eventually shift eastward by D7/Tuesday into D8/Wednesday, allowing for some moisture return into parts of Texas. This could lead to an increase in thunderstorm activity, but the displacement between stronger deep-layer flow/shear and any appreciable surface-based instability currently appears too large to support organized severe potential through early next week. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0300 AM CST Wed Nov 27 2024 Valid 301200Z - 051200Z ...DISCUSSION... Severe-thunderstorm potential still appears low through the extended range. An upper-level trough is expected to persist across the eastern CONUS through the period, as multiple reinforcing shortwaves move southeastward from Canada. A surface ridge covering much of the central/eastern CONUS will inhibit low-level moisture return through most of the extended range. Guidance suggests potential for the surface ridge to eventually shift eastward by D7/Tuesday into D8/Wednesday, allowing for some moisture return into parts of Texas. This could lead to an increase in thunderstorm activity, but the displacement between stronger deep-layer flow/shear and any appreciable surface-based instability currently appears too large to support organized severe potential through early next week. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0300 AM CST Wed Nov 27 2024 Valid 301200Z - 051200Z ...DISCUSSION... Severe-thunderstorm potential still appears low through the extended range. An upper-level trough is expected to persist across the eastern CONUS through the period, as multiple reinforcing shortwaves move southeastward from Canada. A surface ridge covering much of the central/eastern CONUS will inhibit low-level moisture return through most of the extended range. Guidance suggests potential for the surface ridge to eventually shift eastward by D7/Tuesday into D8/Wednesday, allowing for some moisture return into parts of Texas. This could lead to an increase in thunderstorm activity, but the displacement between stronger deep-layer flow/shear and any appreciable surface-based instability currently appears too large to support organized severe potential through early next week. Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0204 AM CST Wed Nov 27 2024 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not currently expected on Friday. ...Synopsis... A deep upper-level trough will encompass much of eastern North America on Friday. A cold front, which may be accompanied by isolated thunderstorms, will continue moving southward across the Gulf of Mexico and the Florida Peninsula. Elsewhere, an expansive surface ridge will maintain dry and stable conditions across most of the CONUS, limiting thunderstorm potential. ...Florida... Strong deep-layer flow will overlap modest buoyancy along/ahead of the front across parts of the FL Peninsula on Friday, and a strong storm or two cannot be ruled out early in the period. However, deep convection may be impeded by weak frontal convergence and a capping inversion aloft, in the absence of stronger large-scale ascent. Weak elevated convection will be possible to the cool side of the front, which could pose a low-probability threat of isolated/sporadic lightning flashes. ..Dean.. 11/27/2024 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0204 AM CST Wed Nov 27 2024 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not currently expected on Friday. ...Synopsis... A deep upper-level trough will encompass much of eastern North America on Friday. A cold front, which may be accompanied by isolated thunderstorms, will continue moving southward across the Gulf of Mexico and the Florida Peninsula. Elsewhere, an expansive surface ridge will maintain dry and stable conditions across most of the CONUS, limiting thunderstorm potential. ...Florida... Strong deep-layer flow will overlap modest buoyancy along/ahead of the front across parts of the FL Peninsula on Friday, and a strong storm or two cannot be ruled out early in the period. However, deep convection may be impeded by weak frontal convergence and a capping inversion aloft, in the absence of stronger large-scale ascent. Weak elevated convection will be possible to the cool side of the front, which could pose a low-probability threat of isolated/sporadic lightning flashes. ..Dean.. 11/27/2024 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0204 AM CST Wed Nov 27 2024 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not currently expected on Friday. ...Synopsis... A deep upper-level trough will encompass much of eastern North America on Friday. A cold front, which may be accompanied by isolated thunderstorms, will continue moving southward across the Gulf of Mexico and the Florida Peninsula. Elsewhere, an expansive surface ridge will maintain dry and stable conditions across most of the CONUS, limiting thunderstorm potential. ...Florida... Strong deep-layer flow will overlap modest buoyancy along/ahead of the front across parts of the FL Peninsula on Friday, and a strong storm or two cannot be ruled out early in the period. However, deep convection may be impeded by weak frontal convergence and a capping inversion aloft, in the absence of stronger large-scale ascent. Weak elevated convection will be possible to the cool side of the front, which could pose a low-probability threat of isolated/sporadic lightning flashes. ..Dean.. 11/27/2024 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0204 AM CST Wed Nov 27 2024 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not currently expected on Friday. ...Synopsis... A deep upper-level trough will encompass much of eastern North America on Friday. A cold front, which may be accompanied by isolated thunderstorms, will continue moving southward across the Gulf of Mexico and the Florida Peninsula. Elsewhere, an expansive surface ridge will maintain dry and stable conditions across most of the CONUS, limiting thunderstorm potential. ...Florida... Strong deep-layer flow will overlap modest buoyancy along/ahead of the front across parts of the FL Peninsula on Friday, and a strong storm or two cannot be ruled out early in the period. However, deep convection may be impeded by weak frontal convergence and a capping inversion aloft, in the absence of stronger large-scale ascent. Weak elevated convection will be possible to the cool side of the front, which could pose a low-probability threat of isolated/sporadic lightning flashes. ..Dean.. 11/27/2024 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0204 AM CST Wed Nov 27 2024 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not currently expected on Friday. ...Synopsis... A deep upper-level trough will encompass much of eastern North America on Friday. A cold front, which may be accompanied by isolated thunderstorms, will continue moving southward across the Gulf of Mexico and the Florida Peninsula. Elsewhere, an expansive surface ridge will maintain dry and stable conditions across most of the CONUS, limiting thunderstorm potential. ...Florida... Strong deep-layer flow will overlap modest buoyancy along/ahead of the front across parts of the FL Peninsula on Friday, and a strong storm or two cannot be ruled out early in the period. However, deep convection may be impeded by weak frontal convergence and a capping inversion aloft, in the absence of stronger large-scale ascent. Weak elevated convection will be possible to the cool side of the front, which could pose a low-probability threat of isolated/sporadic lightning flashes. ..Dean.. 11/27/2024 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0204 AM CST Wed Nov 27 2024 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not currently expected on Friday. ...Synopsis... A deep upper-level trough will encompass much of eastern North America on Friday. A cold front, which may be accompanied by isolated thunderstorms, will continue moving southward across the Gulf of Mexico and the Florida Peninsula. Elsewhere, an expansive surface ridge will maintain dry and stable conditions across most of the CONUS, limiting thunderstorm potential. ...Florida... Strong deep-layer flow will overlap modest buoyancy along/ahead of the front across parts of the FL Peninsula on Friday, and a strong storm or two cannot be ruled out early in the period. However, deep convection may be impeded by weak frontal convergence and a capping inversion aloft, in the absence of stronger large-scale ascent. Weak elevated convection will be possible to the cool side of the front, which could pose a low-probability threat of isolated/sporadic lightning flashes. ..Dean.. 11/27/2024 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CST Wed Nov 27 2024 Valid 281200Z - 291200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE SOUTHEAST/CAROLINAS... ...SUMMARY... Scattered strong to potentially severe thunderstorms are possible Thursday across parts of the Southeast and Carolinas, with the greatest threat currently expected from late morning into the afternoon. Locally damaging wind, isolated hail, and a tornado or two are all possible. ...Synopsis... A large-scale mid/upper-level trough is forecast to amplify across the eastern CONUS on Thanksgiving Day. Within the larger trough, one shortwave will take on a negative tilt as it moves quickly east-northeastward from the OH/TN Valley region toward the Mid Atlantic and New England. In the wake of this leading shortwave trough, a northern-stream shortwave will move southeastward from the northern Great Plains toward the Ohio Valley by the end of the period. A surface cyclone associated with the leading shortwave will deepen as it moves from the Mid Atlantic toward southern New England and eventually the Canadian Maritimes. A trailing cold front will move across parts of the Carolinas/Virginia and the Southeast. ...Southeast into the Carolinas... Given the inconsistent signal for robust storm development, a Marginal Risk was maintained with this outlook. However, greater probabilities for all hazards may be needed if confidence increases regarding a sufficient coverage of organized storms through the day. Strong deep-layer flow/shear (with 60-80 kt flow at 500 mb) will be in place atop the relatively moist boundary layer across parts of the Southeast/Carolinas, prior to the frontal passage. Prefrontal MLCAPE is expected to generally be in the 500-1000 J/kg range, with higher values possible where stronger diurnal heating occurs. The resulting environment will be conditionally favorable for organized convection due to the strong deep-layer shear and sufficient instability. However, some weakening and veering of low-level flow is expected with time, as the primary cyclone and stronger large-scale ascent move quickly northeastward away from the region. As a result, uncertainty remains regarding the coverage and intensity of storms along/ahead of the front. Thunderstorms may develop or be ongoing during the morning, though the coverage and intensity of early-day convection remains unclear. Gradual intensification of ongoing convection and/or additional storm development will be possible with time, both along the front, and potentially in the warm sector if sufficient heating can remove any lingering MLCINH. The relatively modest large-scale ascent may limit storm coverage, but also potentially allow for a discrete or clustered supercell mode with the storms that do form. Any sustained supercells could pose an all-hazards severe threat, especially from GA into the Carolinas, where stronger low-level flow/shear may persist through the morning into at least the early afternoon, to the south of the surface low track. The 00Z HRRR/FV3 depict potential supercell development along/ahead of the front, but other 00Z HREF members show only minimal to very isolated organized storm development. Other guidance has generally trended toward a faster frontal passage (as depicted by the ECMWF/UKMET), which could be less favorable for organized storm potential due to reduced time for diurnal destabilization. Additional trimming of the Marginal Risk from the north may be needed if the trend toward a faster frontal passage continues. ..Dean.. 11/27/2024 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CST Wed Nov 27 2024 Valid 281200Z - 291200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE SOUTHEAST/CAROLINAS... ...SUMMARY... Scattered strong to potentially severe thunderstorms are possible Thursday across parts of the Southeast and Carolinas, with the greatest threat currently expected from late morning into the afternoon. Locally damaging wind, isolated hail, and a tornado or two are all possible. ...Synopsis... A large-scale mid/upper-level trough is forecast to amplify across the eastern CONUS on Thanksgiving Day. Within the larger trough, one shortwave will take on a negative tilt as it moves quickly east-northeastward from the OH/TN Valley region toward the Mid Atlantic and New England. In the wake of this leading shortwave trough, a northern-stream shortwave will move southeastward from the northern Great Plains toward the Ohio Valley by the end of the period. A surface cyclone associated with the leading shortwave will deepen as it moves from the Mid Atlantic toward southern New England and eventually the Canadian Maritimes. A trailing cold front will move across parts of the Carolinas/Virginia and the Southeast. ...Southeast into the Carolinas... Given the inconsistent signal for robust storm development, a Marginal Risk was maintained with this outlook. However, greater probabilities for all hazards may be needed if confidence increases regarding a sufficient coverage of organized storms through the day. Strong deep-layer flow/shear (with 60-80 kt flow at 500 mb) will be in place atop the relatively moist boundary layer across parts of the Southeast/Carolinas, prior to the frontal passage. Prefrontal MLCAPE is expected to generally be in the 500-1000 J/kg range, with higher values possible where stronger diurnal heating occurs. The resulting environment will be conditionally favorable for organized convection due to the strong deep-layer shear and sufficient instability. However, some weakening and veering of low-level flow is expected with time, as the primary cyclone and stronger large-scale ascent move quickly northeastward away from the region. As a result, uncertainty remains regarding the coverage and intensity of storms along/ahead of the front. Thunderstorms may develop or be ongoing during the morning, though the coverage and intensity of early-day convection remains unclear. Gradual intensification of ongoing convection and/or additional storm development will be possible with time, both along the front, and potentially in the warm sector if sufficient heating can remove any lingering MLCINH. The relatively modest large-scale ascent may limit storm coverage, but also potentially allow for a discrete or clustered supercell mode with the storms that do form. Any sustained supercells could pose an all-hazards severe threat, especially from GA into the Carolinas, where stronger low-level flow/shear may persist through the morning into at least the early afternoon, to the south of the surface low track. The 00Z HRRR/FV3 depict potential supercell development along/ahead of the front, but other 00Z HREF members show only minimal to very isolated organized storm development. Other guidance has generally trended toward a faster frontal passage (as depicted by the ECMWF/UKMET), which could be less favorable for organized storm potential due to reduced time for diurnal destabilization. Additional trimming of the Marginal Risk from the north may be needed if the trend toward a faster frontal passage continues. ..Dean.. 11/27/2024 Read more