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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1122 AM CST Sun Nov 19 2023 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF NORTHERN LOUISIANA AND CENTRAL MISSISSIPPI... ...SUMMARY... Severe thunderstorms are likely Monday afternoon into Monday night from east Texas into parts of the Lower-Mississippi Valley and Southeast. Damaging winds and several tornadoes, a few of which may be strong, will be the primary hazards. However, some large hail is also possible. ...Synopsis... A strong mid-level jet streak across Texas will shift east during the day and into the mid-Mississippi Valley by Monday night. A surface low will move eastward through the day from near the Red River, into the Mid-Mississippi Valley, and then occlude northward into the Lower-Ohio Valley by early Tuesday morning. A warm front will move north during the day across the Lower-Mississippi Valley and bring mid-60s dewpoints into the I-20 corridor during the afternoon. Thunderstorm activity is expected along and primarily ahead of a cold front which will move from east Texas Monday afternoon to central/east-central Mississippi by 12Z Tuesday. ...Portions of northern Louisiana and central Mississippi... Expect relatively early convective initiation across east-central Texas, near the nose of the mid-level jet, where morning low temperatures will be in the mid to upper 60s with convective temperatures in the low 70s amid at least broken cloud cover. While shear will be strong (50+ knots), expect storm intensification to be gradual given ~750 MLCAPE and limited inhibition. However, by mid-afternoon as storms move into Louisiana, expect more robust storm development as instability increases and forcing for ascent intensifies as the mid-level trough starts to become more negatively tilted. Significant mass response is expected after 21Z which will lead to a strengthening low-level jet and low-level shear. This timing will correspond well to peak diurnal heating and supercell intensity. As hodographs elongate between 21Z and 00Z, the low-level wind profile will become increasingly favorable with nearly pure streamwise vorticity in the lowest 750m of most forecast soundings. Most CAM guidance shows mature supercells in the region at this time which would support tornado potential, some potentially strong. Diurnal thunderstorm activity is expected to become more linear through the evening with an increasing damaging wind threat. However, as the low-level jet intensifies, increasing isentropic ascent may be sufficient for additional warm-sector supercell development across Mississippi during the evening and into the overnight hours. The less favorable diurnal timing casts some doubt on the intensity of these supercells, but the wind profile will be extremely favorable (300+ m2/s2 0-500m SRH). Therefore, any strong supercells which develop in this region after dark would pose some strong tornado threat. ...Mid-Mississippi Valley... The majority of 12Z CAM guidance shows a surface low track across northwest Mississippi. Therefore, the categorical Slight risk closely matches this mean surface low track. However, some guidance has a farther north track, most notably the FV3 near the MO Bootheel. Therefore since the Marginal risk is conditional on the surface low track, it now extends to the MO Bootheel, indicating the most likely northernmost extent of any potential threat for isolated damaging wind gusts from a low-CAPE convective line along the surface front. ..Bentley.. 11/19/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1122 AM CST Sun Nov 19 2023 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF NORTHERN LOUISIANA AND CENTRAL MISSISSIPPI... ...SUMMARY... Severe thunderstorms are likely Monday afternoon into Monday night from east Texas into parts of the Lower-Mississippi Valley and Southeast. Damaging winds and several tornadoes, a few of which may be strong, will be the primary hazards. However, some large hail is also possible. ...Synopsis... A strong mid-level jet streak across Texas will shift east during the day and into the mid-Mississippi Valley by Monday night. A surface low will move eastward through the day from near the Red River, into the Mid-Mississippi Valley, and then occlude northward into the Lower-Ohio Valley by early Tuesday morning. A warm front will move north during the day across the Lower-Mississippi Valley and bring mid-60s dewpoints into the I-20 corridor during the afternoon. Thunderstorm activity is expected along and primarily ahead of a cold front which will move from east Texas Monday afternoon to central/east-central Mississippi by 12Z Tuesday. ...Portions of northern Louisiana and central Mississippi... Expect relatively early convective initiation across east-central Texas, near the nose of the mid-level jet, where morning low temperatures will be in the mid to upper 60s with convective temperatures in the low 70s amid at least broken cloud cover. While shear will be strong (50+ knots), expect storm intensification to be gradual given ~750 MLCAPE and limited inhibition. However, by mid-afternoon as storms move into Louisiana, expect more robust storm development as instability increases and forcing for ascent intensifies as the mid-level trough starts to become more negatively tilted. Significant mass response is expected after 21Z which will lead to a strengthening low-level jet and low-level shear. This timing will correspond well to peak diurnal heating and supercell intensity. As hodographs elongate between 21Z and 00Z, the low-level wind profile will become increasingly favorable with nearly pure streamwise vorticity in the lowest 750m of most forecast soundings. Most CAM guidance shows mature supercells in the region at this time which would support tornado potential, some potentially strong. Diurnal thunderstorm activity is expected to become more linear through the evening with an increasing damaging wind threat. However, as the low-level jet intensifies, increasing isentropic ascent may be sufficient for additional warm-sector supercell development across Mississippi during the evening and into the overnight hours. The less favorable diurnal timing casts some doubt on the intensity of these supercells, but the wind profile will be extremely favorable (300+ m2/s2 0-500m SRH). Therefore, any strong supercells which develop in this region after dark would pose some strong tornado threat. ...Mid-Mississippi Valley... The majority of 12Z CAM guidance shows a surface low track across northwest Mississippi. Therefore, the categorical Slight risk closely matches this mean surface low track. However, some guidance has a farther north track, most notably the FV3 near the MO Bootheel. Therefore since the Marginal risk is conditional on the surface low track, it now extends to the MO Bootheel, indicating the most likely northernmost extent of any potential threat for isolated damaging wind gusts from a low-CAPE convective line along the surface front. ..Bentley.. 11/19/2023 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1033 AM CST Sun Nov 19 2023 Valid 191700Z - 201200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. ..Wendt.. 11/19/2023 .PREV DISCUSSION... /ISSUED 0156 AM CST Sun Nov 19 2023/ ...Synopsis... A broad western US trough is forecast to amplify considerably through the period as it digs southeastward toward the Four Corners later tonight. Strong mid-level flow along the back of the trough will move onshore over the West Coast as Pacific ridging intensifies farther west. Surface high pressure will intensify over the northern Great Basin, helping to strengthen surface pressure gradients over parts of southern CA late tonight into early Monday. Gusty winds are possible over parts of southern CA and the lower CO River Valley. However, recent precipitation and only modest RH decreases should keep fire-weather concerns low. Fire-weather concerns are also expected to remain localized across the southern Appalachians and TN Valley where high pressure will support dry surface conditions, but weak winds. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1033 AM CST Sun Nov 19 2023 Valid 191700Z - 201200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. ..Wendt.. 11/19/2023 .PREV DISCUSSION... /ISSUED 0156 AM CST Sun Nov 19 2023/ ...Synopsis... A broad western US trough is forecast to amplify considerably through the period as it digs southeastward toward the Four Corners later tonight. Strong mid-level flow along the back of the trough will move onshore over the West Coast as Pacific ridging intensifies farther west. Surface high pressure will intensify over the northern Great Basin, helping to strengthen surface pressure gradients over parts of southern CA late tonight into early Monday. Gusty winds are possible over parts of southern CA and the lower CO River Valley. However, recent precipitation and only modest RH decreases should keep fire-weather concerns low. Fire-weather concerns are also expected to remain localized across the southern Appalachians and TN Valley where high pressure will support dry surface conditions, but weak winds. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1033 AM CST Sun Nov 19 2023 Valid 191700Z - 201200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. ..Wendt.. 11/19/2023 .PREV DISCUSSION... /ISSUED 0156 AM CST Sun Nov 19 2023/ ...Synopsis... A broad western US trough is forecast to amplify considerably through the period as it digs southeastward toward the Four Corners later tonight. Strong mid-level flow along the back of the trough will move onshore over the West Coast as Pacific ridging intensifies farther west. Surface high pressure will intensify over the northern Great Basin, helping to strengthen surface pressure gradients over parts of southern CA late tonight into early Monday. Gusty winds are possible over parts of southern CA and the lower CO River Valley. However, recent precipitation and only modest RH decreases should keep fire-weather concerns low. Fire-weather concerns are also expected to remain localized across the southern Appalachians and TN Valley where high pressure will support dry surface conditions, but weak winds. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1033 AM CST Sun Nov 19 2023 Valid 191700Z - 201200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. ..Wendt.. 11/19/2023 .PREV DISCUSSION... /ISSUED 0156 AM CST Sun Nov 19 2023/ ...Synopsis... A broad western US trough is forecast to amplify considerably through the period as it digs southeastward toward the Four Corners later tonight. Strong mid-level flow along the back of the trough will move onshore over the West Coast as Pacific ridging intensifies farther west. Surface high pressure will intensify over the northern Great Basin, helping to strengthen surface pressure gradients over parts of southern CA late tonight into early Monday. Gusty winds are possible over parts of southern CA and the lower CO River Valley. However, recent precipitation and only modest RH decreases should keep fire-weather concerns low. Fire-weather concerns are also expected to remain localized across the southern Appalachians and TN Valley where high pressure will support dry surface conditions, but weak winds. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1033 AM CST Sun Nov 19 2023 Valid 191700Z - 201200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. ..Wendt.. 11/19/2023 .PREV DISCUSSION... /ISSUED 0156 AM CST Sun Nov 19 2023/ ...Synopsis... A broad western US trough is forecast to amplify considerably through the period as it digs southeastward toward the Four Corners later tonight. Strong mid-level flow along the back of the trough will move onshore over the West Coast as Pacific ridging intensifies farther west. Surface high pressure will intensify over the northern Great Basin, helping to strengthen surface pressure gradients over parts of southern CA late tonight into early Monday. Gusty winds are possible over parts of southern CA and the lower CO River Valley. However, recent precipitation and only modest RH decreases should keep fire-weather concerns low. Fire-weather concerns are also expected to remain localized across the southern Appalachians and TN Valley where high pressure will support dry surface conditions, but weak winds. ...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 1027 AM CST Sun Nov 19 2023 Valid 191630Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL AND NORTHERN OKLAHOMA... ...SUMMARY... Marginally severe hail may occur with evening/overnight thunderstorms in parts of Oklahoma. ...Central/northern Oklahoma... Multiple, mostly low amplitude, mid-level perturbations were observed rotating around a large upper trough over the western/central U.S. as of 16z. A broad, meridionally elongated, area of surface low pressure extending from western KS southward into the TX Panhandle late this morning will gradually consolidate over southwest OK vicinity through tonight. Multiple rounds of showers and thunderstorms will continue today across portions of KS, OK and northern TX within a zone of low-level warm advection and aided by ascent with lead impulses. With time, cooling mid-level temperatures as the upper trough approaches and continued low-level warm/moist advection will support MUCAPE of 500-locally 1000 J/kg over OK this evening and tonight. Effective shear values of 30-40 kts will lead to sufficient updraft organization for a few stronger elevated storms to be capable of marginally severe hail. ..Bunting/Kerr.. 11/19/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1027 AM CST Sun Nov 19 2023 Valid 191630Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL AND NORTHERN OKLAHOMA... ...SUMMARY... Marginally severe hail may occur with evening/overnight thunderstorms in parts of Oklahoma. ...Central/northern Oklahoma... Multiple, mostly low amplitude, mid-level perturbations were observed rotating around a large upper trough over the western/central U.S. as of 16z. A broad, meridionally elongated, area of surface low pressure extending from western KS southward into the TX Panhandle late this morning will gradually consolidate over southwest OK vicinity through tonight. Multiple rounds of showers and thunderstorms will continue today across portions of KS, OK and northern TX within a zone of low-level warm advection and aided by ascent with lead impulses. With time, cooling mid-level temperatures as the upper trough approaches and continued low-level warm/moist advection will support MUCAPE of 500-locally 1000 J/kg over OK this evening and tonight. Effective shear values of 30-40 kts will lead to sufficient updraft organization for a few stronger elevated storms to be capable of marginally severe hail. ..Bunting/Kerr.. 11/19/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1027 AM CST Sun Nov 19 2023 Valid 191630Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL AND NORTHERN OKLAHOMA... ...SUMMARY... Marginally severe hail may occur with evening/overnight thunderstorms in parts of Oklahoma. ...Central/northern Oklahoma... Multiple, mostly low amplitude, mid-level perturbations were observed rotating around a large upper trough over the western/central U.S. as of 16z. A broad, meridionally elongated, area of surface low pressure extending from western KS southward into the TX Panhandle late this morning will gradually consolidate over southwest OK vicinity through tonight. Multiple rounds of showers and thunderstorms will continue today across portions of KS, OK and northern TX within a zone of low-level warm advection and aided by ascent with lead impulses. With time, cooling mid-level temperatures as the upper trough approaches and continued low-level warm/moist advection will support MUCAPE of 500-locally 1000 J/kg over OK this evening and tonight. Effective shear values of 30-40 kts will lead to sufficient updraft organization for a few stronger elevated storms to be capable of marginally severe hail. ..Bunting/Kerr.. 11/19/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1027 AM CST Sun Nov 19 2023 Valid 191630Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL AND NORTHERN OKLAHOMA... ...SUMMARY... Marginally severe hail may occur with evening/overnight thunderstorms in parts of Oklahoma. ...Central/northern Oklahoma... Multiple, mostly low amplitude, mid-level perturbations were observed rotating around a large upper trough over the western/central U.S. as of 16z. A broad, meridionally elongated, area of surface low pressure extending from western KS southward into the TX Panhandle late this morning will gradually consolidate over southwest OK vicinity through tonight. Multiple rounds of showers and thunderstorms will continue today across portions of KS, OK and northern TX within a zone of low-level warm advection and aided by ascent with lead impulses. With time, cooling mid-level temperatures as the upper trough approaches and continued low-level warm/moist advection will support MUCAPE of 500-locally 1000 J/kg over OK this evening and tonight. Effective shear values of 30-40 kts will lead to sufficient updraft organization for a few stronger elevated storms to be capable of marginally severe hail. ..Bunting/Kerr.. 11/19/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1027 AM CST Sun Nov 19 2023 Valid 191630Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL AND NORTHERN OKLAHOMA... ...SUMMARY... Marginally severe hail may occur with evening/overnight thunderstorms in parts of Oklahoma. ...Central/northern Oklahoma... Multiple, mostly low amplitude, mid-level perturbations were observed rotating around a large upper trough over the western/central U.S. as of 16z. A broad, meridionally elongated, area of surface low pressure extending from western KS southward into the TX Panhandle late this morning will gradually consolidate over southwest OK vicinity through tonight. Multiple rounds of showers and thunderstorms will continue today across portions of KS, OK and northern TX within a zone of low-level warm advection and aided by ascent with lead impulses. With time, cooling mid-level temperatures as the upper trough approaches and continued low-level warm/moist advection will support MUCAPE of 500-locally 1000 J/kg over OK this evening and tonight. Effective shear values of 30-40 kts will lead to sufficient updraft organization for a few stronger elevated storms to be capable of marginally severe hail. ..Bunting/Kerr.. 11/19/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0638 AM CST Sun Nov 19 2023 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF CENTRAL/EASTERN OKLAHOMA... ...SUMMARY... Marginally severe hail may occur with evening/overnight thunderstorms in parts of Oklahoma. ...Synopsis... In mid/upper levels, a broad area of cyclonic flow, with multiple shortwaves and vorticity lobes of varying intensity, is apparent in moisture-channel imagery over much of the western/central CONUS. Those perturbations will consolidate into a large, complex cyclone by 12Z tomorrow, extending from the central Plains to the southern High Plains. The strongest of the shortwave troughs is located in the rear side of this configuration, from offshore of Vancouver Island southeastward to parts of NV. The southern part of this perturbation is expected to dig southeastward across the Four Corners region around 00Z, reaching the TX Panhandle and eastern/ southern NM by 12Z. In response, an elongated area of surface low pressure -- analyzed at 11Z near the CO/KS border -- should consolidate and move/ redevelop erratically southward toward west-central/southwestern OK by 06Z, pivoting over central OK by the end of the period. As the cyclogenesis proceeds in a residual continental/polar (cP) airmass, surface frontal features (especially warm frontal) will be nebulous this period. Still, a strengthening cold front should extend from the low across parts of northwest/west-central TX by 12Z, overtaking a developing dryline from north to south. ...OK... Multiple rounds of thunderstorms are possible today and tonight over the southern Plains, from southern KS across central/eastern OK to north-central/northeast TX. Activity will be supported by a fetch of elevated low-level warm advection and strong moisture transport -- above a relatively stable boundary layer. Return flow will be relatively immature -- even above the surface -- as upstream trajectories of cP air that followed the last frontal passage continue to modify. Buoyancy should diminish northward into more precip-laden air, with less-modified inflow parcels. Deep combined lift (from low-level warm advection, divergence-related jet dynamics aloft, and shots of midlevel DCVA preceding the main trough), will weaken southward. The most favorable overlap between those processes, in support of sustained/organized thunderstorms, still appears to be in or very near the outlook area, especially this evening and tonight. That is when low-level/inflow-layer theta-e and cooling aloft each will be greatest, and LFC lowest (but still elevated atop a stable boundary layer). As lapse rates above the boundary layer steepen rapidly tonight, MUCAPE should strengthen into the 500-1000 J/kg range -- rooted near 850 mb and distributed well through the hail-growth zone -- with effective-shear magnitudes peaking in the 30-40-kt range. This will support isolated severe-hail potential with the best-organized cells. ..Edwards/Leitman.. 11/19/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0638 AM CST Sun Nov 19 2023 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF CENTRAL/EASTERN OKLAHOMA... ...SUMMARY... Marginally severe hail may occur with evening/overnight thunderstorms in parts of Oklahoma. ...Synopsis... In mid/upper levels, a broad area of cyclonic flow, with multiple shortwaves and vorticity lobes of varying intensity, is apparent in moisture-channel imagery over much of the western/central CONUS. Those perturbations will consolidate into a large, complex cyclone by 12Z tomorrow, extending from the central Plains to the southern High Plains. The strongest of the shortwave troughs is located in the rear side of this configuration, from offshore of Vancouver Island southeastward to parts of NV. The southern part of this perturbation is expected to dig southeastward across the Four Corners region around 00Z, reaching the TX Panhandle and eastern/ southern NM by 12Z. In response, an elongated area of surface low pressure -- analyzed at 11Z near the CO/KS border -- should consolidate and move/ redevelop erratically southward toward west-central/southwestern OK by 06Z, pivoting over central OK by the end of the period. As the cyclogenesis proceeds in a residual continental/polar (cP) airmass, surface frontal features (especially warm frontal) will be nebulous this period. Still, a strengthening cold front should extend from the low across parts of northwest/west-central TX by 12Z, overtaking a developing dryline from north to south. ...OK... Multiple rounds of thunderstorms are possible today and tonight over the southern Plains, from southern KS across central/eastern OK to north-central/northeast TX. Activity will be supported by a fetch of elevated low-level warm advection and strong moisture transport -- above a relatively stable boundary layer. Return flow will be relatively immature -- even above the surface -- as upstream trajectories of cP air that followed the last frontal passage continue to modify. Buoyancy should diminish northward into more precip-laden air, with less-modified inflow parcels. Deep combined lift (from low-level warm advection, divergence-related jet dynamics aloft, and shots of midlevel DCVA preceding the main trough), will weaken southward. The most favorable overlap between those processes, in support of sustained/organized thunderstorms, still appears to be in or very near the outlook area, especially this evening and tonight. That is when low-level/inflow-layer theta-e and cooling aloft each will be greatest, and LFC lowest (but still elevated atop a stable boundary layer). As lapse rates above the boundary layer steepen rapidly tonight, MUCAPE should strengthen into the 500-1000 J/kg range -- rooted near 850 mb and distributed well through the hail-growth zone -- with effective-shear magnitudes peaking in the 30-40-kt range. This will support isolated severe-hail potential with the best-organized cells. ..Edwards/Leitman.. 11/19/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0638 AM CST Sun Nov 19 2023 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF CENTRAL/EASTERN OKLAHOMA... ...SUMMARY... Marginally severe hail may occur with evening/overnight thunderstorms in parts of Oklahoma. ...Synopsis... In mid/upper levels, a broad area of cyclonic flow, with multiple shortwaves and vorticity lobes of varying intensity, is apparent in moisture-channel imagery over much of the western/central CONUS. Those perturbations will consolidate into a large, complex cyclone by 12Z tomorrow, extending from the central Plains to the southern High Plains. The strongest of the shortwave troughs is located in the rear side of this configuration, from offshore of Vancouver Island southeastward to parts of NV. The southern part of this perturbation is expected to dig southeastward across the Four Corners region around 00Z, reaching the TX Panhandle and eastern/ southern NM by 12Z. In response, an elongated area of surface low pressure -- analyzed at 11Z near the CO/KS border -- should consolidate and move/ redevelop erratically southward toward west-central/southwestern OK by 06Z, pivoting over central OK by the end of the period. As the cyclogenesis proceeds in a residual continental/polar (cP) airmass, surface frontal features (especially warm frontal) will be nebulous this period. Still, a strengthening cold front should extend from the low across parts of northwest/west-central TX by 12Z, overtaking a developing dryline from north to south. ...OK... Multiple rounds of thunderstorms are possible today and tonight over the southern Plains, from southern KS across central/eastern OK to north-central/northeast TX. Activity will be supported by a fetch of elevated low-level warm advection and strong moisture transport -- above a relatively stable boundary layer. Return flow will be relatively immature -- even above the surface -- as upstream trajectories of cP air that followed the last frontal passage continue to modify. Buoyancy should diminish northward into more precip-laden air, with less-modified inflow parcels. Deep combined lift (from low-level warm advection, divergence-related jet dynamics aloft, and shots of midlevel DCVA preceding the main trough), will weaken southward. The most favorable overlap between those processes, in support of sustained/organized thunderstorms, still appears to be in or very near the outlook area, especially this evening and tonight. That is when low-level/inflow-layer theta-e and cooling aloft each will be greatest, and LFC lowest (but still elevated atop a stable boundary layer). As lapse rates above the boundary layer steepen rapidly tonight, MUCAPE should strengthen into the 500-1000 J/kg range -- rooted near 850 mb and distributed well through the hail-growth zone -- with effective-shear magnitudes peaking in the 30-40-kt range. This will support isolated severe-hail potential with the best-organized cells. ..Edwards/Leitman.. 11/19/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0638 AM CST Sun Nov 19 2023 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF CENTRAL/EASTERN OKLAHOMA... ...SUMMARY... Marginally severe hail may occur with evening/overnight thunderstorms in parts of Oklahoma. ...Synopsis... In mid/upper levels, a broad area of cyclonic flow, with multiple shortwaves and vorticity lobes of varying intensity, is apparent in moisture-channel imagery over much of the western/central CONUS. Those perturbations will consolidate into a large, complex cyclone by 12Z tomorrow, extending from the central Plains to the southern High Plains. The strongest of the shortwave troughs is located in the rear side of this configuration, from offshore of Vancouver Island southeastward to parts of NV. The southern part of this perturbation is expected to dig southeastward across the Four Corners region around 00Z, reaching the TX Panhandle and eastern/ southern NM by 12Z. In response, an elongated area of surface low pressure -- analyzed at 11Z near the CO/KS border -- should consolidate and move/ redevelop erratically southward toward west-central/southwestern OK by 06Z, pivoting over central OK by the end of the period. As the cyclogenesis proceeds in a residual continental/polar (cP) airmass, surface frontal features (especially warm frontal) will be nebulous this period. Still, a strengthening cold front should extend from the low across parts of northwest/west-central TX by 12Z, overtaking a developing dryline from north to south. ...OK... Multiple rounds of thunderstorms are possible today and tonight over the southern Plains, from southern KS across central/eastern OK to north-central/northeast TX. Activity will be supported by a fetch of elevated low-level warm advection and strong moisture transport -- above a relatively stable boundary layer. Return flow will be relatively immature -- even above the surface -- as upstream trajectories of cP air that followed the last frontal passage continue to modify. Buoyancy should diminish northward into more precip-laden air, with less-modified inflow parcels. Deep combined lift (from low-level warm advection, divergence-related jet dynamics aloft, and shots of midlevel DCVA preceding the main trough), will weaken southward. The most favorable overlap between those processes, in support of sustained/organized thunderstorms, still appears to be in or very near the outlook area, especially this evening and tonight. That is when low-level/inflow-layer theta-e and cooling aloft each will be greatest, and LFC lowest (but still elevated atop a stable boundary layer). As lapse rates above the boundary layer steepen rapidly tonight, MUCAPE should strengthen into the 500-1000 J/kg range -- rooted near 850 mb and distributed well through the hail-growth zone -- with effective-shear magnitudes peaking in the 30-40-kt range. This will support isolated severe-hail potential with the best-organized cells. ..Edwards/Leitman.. 11/19/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0638 AM CST Sun Nov 19 2023 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF CENTRAL/EASTERN OKLAHOMA... ...SUMMARY... Marginally severe hail may occur with evening/overnight thunderstorms in parts of Oklahoma. ...Synopsis... In mid/upper levels, a broad area of cyclonic flow, with multiple shortwaves and vorticity lobes of varying intensity, is apparent in moisture-channel imagery over much of the western/central CONUS. Those perturbations will consolidate into a large, complex cyclone by 12Z tomorrow, extending from the central Plains to the southern High Plains. The strongest of the shortwave troughs is located in the rear side of this configuration, from offshore of Vancouver Island southeastward to parts of NV. The southern part of this perturbation is expected to dig southeastward across the Four Corners region around 00Z, reaching the TX Panhandle and eastern/ southern NM by 12Z. In response, an elongated area of surface low pressure -- analyzed at 11Z near the CO/KS border -- should consolidate and move/ redevelop erratically southward toward west-central/southwestern OK by 06Z, pivoting over central OK by the end of the period. As the cyclogenesis proceeds in a residual continental/polar (cP) airmass, surface frontal features (especially warm frontal) will be nebulous this period. Still, a strengthening cold front should extend from the low across parts of northwest/west-central TX by 12Z, overtaking a developing dryline from north to south. ...OK... Multiple rounds of thunderstorms are possible today and tonight over the southern Plains, from southern KS across central/eastern OK to north-central/northeast TX. Activity will be supported by a fetch of elevated low-level warm advection and strong moisture transport -- above a relatively stable boundary layer. Return flow will be relatively immature -- even above the surface -- as upstream trajectories of cP air that followed the last frontal passage continue to modify. Buoyancy should diminish northward into more precip-laden air, with less-modified inflow parcels. Deep combined lift (from low-level warm advection, divergence-related jet dynamics aloft, and shots of midlevel DCVA preceding the main trough), will weaken southward. The most favorable overlap between those processes, in support of sustained/organized thunderstorms, still appears to be in or very near the outlook area, especially this evening and tonight. That is when low-level/inflow-layer theta-e and cooling aloft each will be greatest, and LFC lowest (but still elevated atop a stable boundary layer). As lapse rates above the boundary layer steepen rapidly tonight, MUCAPE should strengthen into the 500-1000 J/kg range -- rooted near 850 mb and distributed well through the hail-growth zone -- with effective-shear magnitudes peaking in the 30-40-kt range. This will support isolated severe-hail potential with the best-organized cells. ..Edwards/Leitman.. 11/19/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0638 AM CST Sun Nov 19 2023 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF CENTRAL/EASTERN OKLAHOMA... ...SUMMARY... Marginally severe hail may occur with evening/overnight thunderstorms in parts of Oklahoma. ...Synopsis... In mid/upper levels, a broad area of cyclonic flow, with multiple shortwaves and vorticity lobes of varying intensity, is apparent in moisture-channel imagery over much of the western/central CONUS. Those perturbations will consolidate into a large, complex cyclone by 12Z tomorrow, extending from the central Plains to the southern High Plains. The strongest of the shortwave troughs is located in the rear side of this configuration, from offshore of Vancouver Island southeastward to parts of NV. The southern part of this perturbation is expected to dig southeastward across the Four Corners region around 00Z, reaching the TX Panhandle and eastern/ southern NM by 12Z. In response, an elongated area of surface low pressure -- analyzed at 11Z near the CO/KS border -- should consolidate and move/ redevelop erratically southward toward west-central/southwestern OK by 06Z, pivoting over central OK by the end of the period. As the cyclogenesis proceeds in a residual continental/polar (cP) airmass, surface frontal features (especially warm frontal) will be nebulous this period. Still, a strengthening cold front should extend from the low across parts of northwest/west-central TX by 12Z, overtaking a developing dryline from north to south. ...OK... Multiple rounds of thunderstorms are possible today and tonight over the southern Plains, from southern KS across central/eastern OK to north-central/northeast TX. Activity will be supported by a fetch of elevated low-level warm advection and strong moisture transport -- above a relatively stable boundary layer. Return flow will be relatively immature -- even above the surface -- as upstream trajectories of cP air that followed the last frontal passage continue to modify. Buoyancy should diminish northward into more precip-laden air, with less-modified inflow parcels. Deep combined lift (from low-level warm advection, divergence-related jet dynamics aloft, and shots of midlevel DCVA preceding the main trough), will weaken southward. The most favorable overlap between those processes, in support of sustained/organized thunderstorms, still appears to be in or very near the outlook area, especially this evening and tonight. That is when low-level/inflow-layer theta-e and cooling aloft each will be greatest, and LFC lowest (but still elevated atop a stable boundary layer). As lapse rates above the boundary layer steepen rapidly tonight, MUCAPE should strengthen into the 500-1000 J/kg range -- rooted near 850 mb and distributed well through the hail-growth zone -- with effective-shear magnitudes peaking in the 30-40-kt range. This will support isolated severe-hail potential with the best-organized cells. ..Edwards/Leitman.. 11/19/2023 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0340 AM CST Sun Nov 19 2023 Valid 221200Z - 271200Z ...DISCUSSION... ...D4/Wednesday - Parts of the Carolinas... Substantial model spread noted in the D3/Tuesday period continues into D4/Wednesday across the Carolinas. While most guidance suggests the cold front will be near the coast or offshore by Wednesday morning, the GFS and some GEFS members depict a notably stronger mid/upper-level cyclone approaching the region Wednesday morning. Should this occur, a surface wave may develop and result in a later frontal passage, with some threat for organized convection potentially developing near the coast. Predictability is much too low to include probabilities for this scenario at this time. ...D6/Friday and D7/Saturday - Parts of the Gulf Coast/Florida... Some extended-range guidance (most notably the deterministic 19/00Z ECMWF) depicts frontal wave development across the Gulf of Mexico late this week, as a cutoff mid/upper-level cyclone finally ejects east-northeastward. This scenario could pose some severe-thunderstorm potential near the Gulf Coast and Florida into next weekend, but predictability is very low at this forecast range, and substantial destabilization in the wake of the earlier frontal passage across the region still appears rather unlikely. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0340 AM CST Sun Nov 19 2023 Valid 221200Z - 271200Z ...DISCUSSION... ...D4/Wednesday - Parts of the Carolinas... Substantial model spread noted in the D3/Tuesday period continues into D4/Wednesday across the Carolinas. While most guidance suggests the cold front will be near the coast or offshore by Wednesday morning, the GFS and some GEFS members depict a notably stronger mid/upper-level cyclone approaching the region Wednesday morning. Should this occur, a surface wave may develop and result in a later frontal passage, with some threat for organized convection potentially developing near the coast. Predictability is much too low to include probabilities for this scenario at this time. ...D6/Friday and D7/Saturday - Parts of the Gulf Coast/Florida... Some extended-range guidance (most notably the deterministic 19/00Z ECMWF) depicts frontal wave development across the Gulf of Mexico late this week, as a cutoff mid/upper-level cyclone finally ejects east-northeastward. This scenario could pose some severe-thunderstorm potential near the Gulf Coast and Florida into next weekend, but predictability is very low at this forecast range, and substantial destabilization in the wake of the earlier frontal passage across the region still appears rather unlikely. Read more