SPC Day 1 Fire Weather Outlook

1 year 8 months ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0158 AM CST Mon Nov 20 2023 Valid 201200Z - 211200Z ...Synopsis... A deep mid-level trough over the central US will drive strong flow aloft southward over parts of southern CA and the lower CO River Valley while ridging develops over the eastern Pacific. High pressure over the northern Great Basin should support offshore flow over parts of southern CA through tonight and into early D2/Tuesday. ...Central Appalachians... Breezy easterly flow is expected over parts of western NC and eastern TN ahead of the surface low as it moves from OK into the mid MS Valley tonight. North of the stalled warm front, the low-level air mass remains relatively dry from the prior frontal passage. While RH values are not expected to reach critical levels, very strong low- and mid-level winds ahead of the surface low are expected to overspread areas of 90th percentile ERCs. Ongoing wildfire activity within the higher terrain could be impacted by strong east/southeast winds and mountain waves for several hours this afternoon into the evening. With this in mind, have opted to include a small elevated on the downwind side of the Smoky Mountains where strong winds could overlap with the driest fuels. Later tonight, widespread rain should develop and end the fire-weather threat. ...Southern High Plains... Very strong flow aloft is expected to overspread parts of the Southern High Plains and eastern NM as the deep mid-level trough begins to move east. Aided by the low over OK, gusty northwest surface winds are possible across west TX and eastern NM Monday afternoon and evening. However, recent rainfall and cooler temperatures in the wake of the passing Pacific front should keep RH above critical levels. Gusty winds still may support brief local fire-weather concerns through the afternoon. ...Southern California... Strong flow aloft along the backside of the central US trough will overspread parts of southern CA late this weekend into early Monday. High pressure over the Great Basin will tighten offshore surface pressure gradients, enhancing surface winds across Point Conception and the lee of the Peninsular Ranges. A few hours of gusty winds and low humidity are likely through tonight before winds begin to weaken into D2/Tuesday morning. However, marginally receptive fuels and the relatively brief period of offshore winds suggest any fire-weather concerns will remain localized. ..Lyons.. 11/20/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

1 year 8 months ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0158 AM CST Mon Nov 20 2023 Valid 201200Z - 211200Z ...Synopsis... A deep mid-level trough over the central US will drive strong flow aloft southward over parts of southern CA and the lower CO River Valley while ridging develops over the eastern Pacific. High pressure over the northern Great Basin should support offshore flow over parts of southern CA through tonight and into early D2/Tuesday. ...Central Appalachians... Breezy easterly flow is expected over parts of western NC and eastern TN ahead of the surface low as it moves from OK into the mid MS Valley tonight. North of the stalled warm front, the low-level air mass remains relatively dry from the prior frontal passage. While RH values are not expected to reach critical levels, very strong low- and mid-level winds ahead of the surface low are expected to overspread areas of 90th percentile ERCs. Ongoing wildfire activity within the higher terrain could be impacted by strong east/southeast winds and mountain waves for several hours this afternoon into the evening. With this in mind, have opted to include a small elevated on the downwind side of the Smoky Mountains where strong winds could overlap with the driest fuels. Later tonight, widespread rain should develop and end the fire-weather threat. ...Southern High Plains... Very strong flow aloft is expected to overspread parts of the Southern High Plains and eastern NM as the deep mid-level trough begins to move east. Aided by the low over OK, gusty northwest surface winds are possible across west TX and eastern NM Monday afternoon and evening. However, recent rainfall and cooler temperatures in the wake of the passing Pacific front should keep RH above critical levels. Gusty winds still may support brief local fire-weather concerns through the afternoon. ...Southern California... Strong flow aloft along the backside of the central US trough will overspread parts of southern CA late this weekend into early Monday. High pressure over the Great Basin will tighten offshore surface pressure gradients, enhancing surface winds across Point Conception and the lee of the Peninsular Ranges. A few hours of gusty winds and low humidity are likely through tonight before winds begin to weaken into D2/Tuesday morning. However, marginally receptive fuels and the relatively brief period of offshore winds suggest any fire-weather concerns will remain localized. ..Lyons.. 11/20/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

1 year 8 months ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0158 AM CST Mon Nov 20 2023 Valid 201200Z - 211200Z ...Synopsis... A deep mid-level trough over the central US will drive strong flow aloft southward over parts of southern CA and the lower CO River Valley while ridging develops over the eastern Pacific. High pressure over the northern Great Basin should support offshore flow over parts of southern CA through tonight and into early D2/Tuesday. ...Central Appalachians... Breezy easterly flow is expected over parts of western NC and eastern TN ahead of the surface low as it moves from OK into the mid MS Valley tonight. North of the stalled warm front, the low-level air mass remains relatively dry from the prior frontal passage. While RH values are not expected to reach critical levels, very strong low- and mid-level winds ahead of the surface low are expected to overspread areas of 90th percentile ERCs. Ongoing wildfire activity within the higher terrain could be impacted by strong east/southeast winds and mountain waves for several hours this afternoon into the evening. With this in mind, have opted to include a small elevated on the downwind side of the Smoky Mountains where strong winds could overlap with the driest fuels. Later tonight, widespread rain should develop and end the fire-weather threat. ...Southern High Plains... Very strong flow aloft is expected to overspread parts of the Southern High Plains and eastern NM as the deep mid-level trough begins to move east. Aided by the low over OK, gusty northwest surface winds are possible across west TX and eastern NM Monday afternoon and evening. However, recent rainfall and cooler temperatures in the wake of the passing Pacific front should keep RH above critical levels. Gusty winds still may support brief local fire-weather concerns through the afternoon. ...Southern California... Strong flow aloft along the backside of the central US trough will overspread parts of southern CA late this weekend into early Monday. High pressure over the Great Basin will tighten offshore surface pressure gradients, enhancing surface winds across Point Conception and the lee of the Peninsular Ranges. A few hours of gusty winds and low humidity are likely through tonight before winds begin to weaken into D2/Tuesday morning. However, marginally receptive fuels and the relatively brief period of offshore winds suggest any fire-weather concerns will remain localized. ..Lyons.. 11/20/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

1 year 8 months ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0158 AM CST Mon Nov 20 2023 Valid 201200Z - 211200Z ...Synopsis... A deep mid-level trough over the central US will drive strong flow aloft southward over parts of southern CA and the lower CO River Valley while ridging develops over the eastern Pacific. High pressure over the northern Great Basin should support offshore flow over parts of southern CA through tonight and into early D2/Tuesday. ...Central Appalachians... Breezy easterly flow is expected over parts of western NC and eastern TN ahead of the surface low as it moves from OK into the mid MS Valley tonight. North of the stalled warm front, the low-level air mass remains relatively dry from the prior frontal passage. While RH values are not expected to reach critical levels, very strong low- and mid-level winds ahead of the surface low are expected to overspread areas of 90th percentile ERCs. Ongoing wildfire activity within the higher terrain could be impacted by strong east/southeast winds and mountain waves for several hours this afternoon into the evening. With this in mind, have opted to include a small elevated on the downwind side of the Smoky Mountains where strong winds could overlap with the driest fuels. Later tonight, widespread rain should develop and end the fire-weather threat. ...Southern High Plains... Very strong flow aloft is expected to overspread parts of the Southern High Plains and eastern NM as the deep mid-level trough begins to move east. Aided by the low over OK, gusty northwest surface winds are possible across west TX and eastern NM Monday afternoon and evening. However, recent rainfall and cooler temperatures in the wake of the passing Pacific front should keep RH above critical levels. Gusty winds still may support brief local fire-weather concerns through the afternoon. ...Southern California... Strong flow aloft along the backside of the central US trough will overspread parts of southern CA late this weekend into early Monday. High pressure over the Great Basin will tighten offshore surface pressure gradients, enhancing surface winds across Point Conception and the lee of the Peninsular Ranges. A few hours of gusty winds and low humidity are likely through tonight before winds begin to weaken into D2/Tuesday morning. However, marginally receptive fuels and the relatively brief period of offshore winds suggest any fire-weather concerns will remain localized. ..Lyons.. 11/20/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

1 year 8 months ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0158 AM CST Mon Nov 20 2023 Valid 201200Z - 211200Z ...Synopsis... A deep mid-level trough over the central US will drive strong flow aloft southward over parts of southern CA and the lower CO River Valley while ridging develops over the eastern Pacific. High pressure over the northern Great Basin should support offshore flow over parts of southern CA through tonight and into early D2/Tuesday. ...Central Appalachians... Breezy easterly flow is expected over parts of western NC and eastern TN ahead of the surface low as it moves from OK into the mid MS Valley tonight. North of the stalled warm front, the low-level air mass remains relatively dry from the prior frontal passage. While RH values are not expected to reach critical levels, very strong low- and mid-level winds ahead of the surface low are expected to overspread areas of 90th percentile ERCs. Ongoing wildfire activity within the higher terrain could be impacted by strong east/southeast winds and mountain waves for several hours this afternoon into the evening. With this in mind, have opted to include a small elevated on the downwind side of the Smoky Mountains where strong winds could overlap with the driest fuels. Later tonight, widespread rain should develop and end the fire-weather threat. ...Southern High Plains... Very strong flow aloft is expected to overspread parts of the Southern High Plains and eastern NM as the deep mid-level trough begins to move east. Aided by the low over OK, gusty northwest surface winds are possible across west TX and eastern NM Monday afternoon and evening. However, recent rainfall and cooler temperatures in the wake of the passing Pacific front should keep RH above critical levels. Gusty winds still may support brief local fire-weather concerns through the afternoon. ...Southern California... Strong flow aloft along the backside of the central US trough will overspread parts of southern CA late this weekend into early Monday. High pressure over the Great Basin will tighten offshore surface pressure gradients, enhancing surface winds across Point Conception and the lee of the Peninsular Ranges. A few hours of gusty winds and low humidity are likely through tonight before winds begin to weaken into D2/Tuesday morning. However, marginally receptive fuels and the relatively brief period of offshore winds suggest any fire-weather concerns will remain localized. ..Lyons.. 11/20/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

1 year 8 months ago
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0158 AM CST Mon Nov 20 2023 Valid 201200Z - 211200Z ...Synopsis... A deep mid-level trough over the central US will drive strong flow aloft southward over parts of southern CA and the lower CO River Valley while ridging develops over the eastern Pacific. High pressure over the northern Great Basin should support offshore flow over parts of southern CA through tonight and into early D2/Tuesday. ...Central Appalachians... Breezy easterly flow is expected over parts of western NC and eastern TN ahead of the surface low as it moves from OK into the mid MS Valley tonight. North of the stalled warm front, the low-level air mass remains relatively dry from the prior frontal passage. While RH values are not expected to reach critical levels, very strong low- and mid-level winds ahead of the surface low are expected to overspread areas of 90th percentile ERCs. Ongoing wildfire activity within the higher terrain could be impacted by strong east/southeast winds and mountain waves for several hours this afternoon into the evening. With this in mind, have opted to include a small elevated on the downwind side of the Smoky Mountains where strong winds could overlap with the driest fuels. Later tonight, widespread rain should develop and end the fire-weather threat. ...Southern High Plains... Very strong flow aloft is expected to overspread parts of the Southern High Plains and eastern NM as the deep mid-level trough begins to move east. Aided by the low over OK, gusty northwest surface winds are possible across west TX and eastern NM Monday afternoon and evening. However, recent rainfall and cooler temperatures in the wake of the passing Pacific front should keep RH above critical levels. Gusty winds still may support brief local fire-weather concerns through the afternoon. ...Southern California... Strong flow aloft along the backside of the central US trough will overspread parts of southern CA late this weekend into early Monday. High pressure over the Great Basin will tighten offshore surface pressure gradients, enhancing surface winds across Point Conception and the lee of the Peninsular Ranges. A few hours of gusty winds and low humidity are likely through tonight before winds begin to weaken into D2/Tuesday morning. However, marginally receptive fuels and the relatively brief period of offshore winds suggest any fire-weather concerns will remain localized. ..Lyons.. 11/20/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Nov 20, 2023 0700 UTC Day 2 Convective Outlook

1 year 8 months ago
SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CST Mon Nov 20 2023 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS A SMALL PART OF SOUTH AL AND THE FL PANHANDLE... ...SUMMARY... A couple tornadoes are possible across parts of south Alabama into the Florida Panhandle, mainly during the morning and early afternoon. Locally damaging winds and perhaps a couple brief tornadoes will also be possible from Georgia into the Carolinas Tuesday afternoon into Tuesday night. ...Synopsis... A vigorous mid/upper-level low is forecast to evolve into an open wave on Tuesday as it moves toward the lower Great Lakes and Northeast through the day. The related surface cyclone will take a similar track, with some weakening expected as it becomes increasingly displaced from the effective warm sector. A trailing cold front will continue to move through parts of the Southeast. One or more surface waves may develop along the effective warm front, with most guidance depicting consolidation of a surface cyclone near or off of the Mid Atlantic coast by Wednesday morning. Guidance continues to vary substantially with regard to large-scale trough evolution in the wake of the departing midlevel low, with the GFS (and now the 20/00Z ECMWF) continuing to amplify a shortwave near the Ozarks/lower MS Valley vicinity, while other guidance maintains a broad positively tilted trough that gradually moves eastward toward the Atlantic Coast. ...Parts of AL/GA and the FL Panhandle... While the primary surface cyclone will continue moving away from the region on Tuesday, convection will likely persist through the day within a confluent regime along/ahead of the front across parts of AL and FL Panhandle, and eventually move into parts of GA. Generally weak instability (with MLCAPE generally less than 500 J/kg away from the immediate coast) may tend to limit storm intensity, but favorable moisture and deep-layer shear will continue to support the potential for at least transient supercell structures. 0-1 km SRH generally in the 150-250 m2/s2 range will support some tornado threat where sufficient destabilization can occur. The threat may peak early in the day across south AL and the FL Panhandle, in association with any supercells that develop during the D1/Monday period and persist into Tuesday morning. A small Slight Risk has been included across this area, as a continuation of the threat from late on D1/Monday. Some threat for locally damaging gusts and/or a brief tornado may persist into the afternoon across parts of GA, in areas where modest diurnal heating can augment generally weak instability. ...Carolinas... A warm front is forecast to move northward across the Carolinas during the day, accompanied by low 60s F dewpoints. While wind profiles will become increasingly favorable for organized convection, instability is expected to remain very weak through the afternoon, due to weak lapse rates and rather widespread cloudiness and precipitation. There is some potential for an organized frontal band to develop and move eastward, which could pose a damaging-wind threat given the expected strength of low-level flow. A conditional Marginal Risk has been included for this threat, though the areal coverage of the convectively enhanced gust threat remains uncertain, due to diminishing instability with northward extent. Strong low-level shear could also support a brief tornado threat if pockets of somewhat greater instability can materialize. Somewhat richer moisture (with dewpoints in the mid 60s F) may advect northward into eastern NC Tuesday evening into the overnight, as low-level flow veers and strengthens some in response to the deepening cyclone near the Mid Atlantic coast. Some uptick in the tornado/wind threat is possible over eastern NC and the Outer Banks as this occurs, though uncertainty remains high regarding evolution of the upper trough (described above) and strength of large-scale ascent across the region during the overnight period. ..Dean.. 11/20/2023 Read more

SPC Nov 20, 2023 0700 UTC Day 2 Convective Outlook

1 year 8 months ago
SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CST Mon Nov 20 2023 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS A SMALL PART OF SOUTH AL AND THE FL PANHANDLE... ...SUMMARY... A couple tornadoes are possible across parts of south Alabama into the Florida Panhandle, mainly during the morning and early afternoon. Locally damaging winds and perhaps a couple brief tornadoes will also be possible from Georgia into the Carolinas Tuesday afternoon into Tuesday night. ...Synopsis... A vigorous mid/upper-level low is forecast to evolve into an open wave on Tuesday as it moves toward the lower Great Lakes and Northeast through the day. The related surface cyclone will take a similar track, with some weakening expected as it becomes increasingly displaced from the effective warm sector. A trailing cold front will continue to move through parts of the Southeast. One or more surface waves may develop along the effective warm front, with most guidance depicting consolidation of a surface cyclone near or off of the Mid Atlantic coast by Wednesday morning. Guidance continues to vary substantially with regard to large-scale trough evolution in the wake of the departing midlevel low, with the GFS (and now the 20/00Z ECMWF) continuing to amplify a shortwave near the Ozarks/lower MS Valley vicinity, while other guidance maintains a broad positively tilted trough that gradually moves eastward toward the Atlantic Coast. ...Parts of AL/GA and the FL Panhandle... While the primary surface cyclone will continue moving away from the region on Tuesday, convection will likely persist through the day within a confluent regime along/ahead of the front across parts of AL and FL Panhandle, and eventually move into parts of GA. Generally weak instability (with MLCAPE generally less than 500 J/kg away from the immediate coast) may tend to limit storm intensity, but favorable moisture and deep-layer shear will continue to support the potential for at least transient supercell structures. 0-1 km SRH generally in the 150-250 m2/s2 range will support some tornado threat where sufficient destabilization can occur. The threat may peak early in the day across south AL and the FL Panhandle, in association with any supercells that develop during the D1/Monday period and persist into Tuesday morning. A small Slight Risk has been included across this area, as a continuation of the threat from late on D1/Monday. Some threat for locally damaging gusts and/or a brief tornado may persist into the afternoon across parts of GA, in areas where modest diurnal heating can augment generally weak instability. ...Carolinas... A warm front is forecast to move northward across the Carolinas during the day, accompanied by low 60s F dewpoints. While wind profiles will become increasingly favorable for organized convection, instability is expected to remain very weak through the afternoon, due to weak lapse rates and rather widespread cloudiness and precipitation. There is some potential for an organized frontal band to develop and move eastward, which could pose a damaging-wind threat given the expected strength of low-level flow. A conditional Marginal Risk has been included for this threat, though the areal coverage of the convectively enhanced gust threat remains uncertain, due to diminishing instability with northward extent. Strong low-level shear could also support a brief tornado threat if pockets of somewhat greater instability can materialize. Somewhat richer moisture (with dewpoints in the mid 60s F) may advect northward into eastern NC Tuesday evening into the overnight, as low-level flow veers and strengthens some in response to the deepening cyclone near the Mid Atlantic coast. Some uptick in the tornado/wind threat is possible over eastern NC and the Outer Banks as this occurs, though uncertainty remains high regarding evolution of the upper trough (described above) and strength of large-scale ascent across the region during the overnight period. ..Dean.. 11/20/2023 Read more

SPC Nov 20, 2023 0700 UTC Day 2 Convective Outlook

1 year 8 months ago
SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CST Mon Nov 20 2023 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS A SMALL PART OF SOUTH AL AND THE FL PANHANDLE... ...SUMMARY... A couple tornadoes are possible across parts of south Alabama into the Florida Panhandle, mainly during the morning and early afternoon. Locally damaging winds and perhaps a couple brief tornadoes will also be possible from Georgia into the Carolinas Tuesday afternoon into Tuesday night. ...Synopsis... A vigorous mid/upper-level low is forecast to evolve into an open wave on Tuesday as it moves toward the lower Great Lakes and Northeast through the day. The related surface cyclone will take a similar track, with some weakening expected as it becomes increasingly displaced from the effective warm sector. A trailing cold front will continue to move through parts of the Southeast. One or more surface waves may develop along the effective warm front, with most guidance depicting consolidation of a surface cyclone near or off of the Mid Atlantic coast by Wednesday morning. Guidance continues to vary substantially with regard to large-scale trough evolution in the wake of the departing midlevel low, with the GFS (and now the 20/00Z ECMWF) continuing to amplify a shortwave near the Ozarks/lower MS Valley vicinity, while other guidance maintains a broad positively tilted trough that gradually moves eastward toward the Atlantic Coast. ...Parts of AL/GA and the FL Panhandle... While the primary surface cyclone will continue moving away from the region on Tuesday, convection will likely persist through the day within a confluent regime along/ahead of the front across parts of AL and FL Panhandle, and eventually move into parts of GA. Generally weak instability (with MLCAPE generally less than 500 J/kg away from the immediate coast) may tend to limit storm intensity, but favorable moisture and deep-layer shear will continue to support the potential for at least transient supercell structures. 0-1 km SRH generally in the 150-250 m2/s2 range will support some tornado threat where sufficient destabilization can occur. The threat may peak early in the day across south AL and the FL Panhandle, in association with any supercells that develop during the D1/Monday period and persist into Tuesday morning. A small Slight Risk has been included across this area, as a continuation of the threat from late on D1/Monday. Some threat for locally damaging gusts and/or a brief tornado may persist into the afternoon across parts of GA, in areas where modest diurnal heating can augment generally weak instability. ...Carolinas... A warm front is forecast to move northward across the Carolinas during the day, accompanied by low 60s F dewpoints. While wind profiles will become increasingly favorable for organized convection, instability is expected to remain very weak through the afternoon, due to weak lapse rates and rather widespread cloudiness and precipitation. There is some potential for an organized frontal band to develop and move eastward, which could pose a damaging-wind threat given the expected strength of low-level flow. A conditional Marginal Risk has been included for this threat, though the areal coverage of the convectively enhanced gust threat remains uncertain, due to diminishing instability with northward extent. Strong low-level shear could also support a brief tornado threat if pockets of somewhat greater instability can materialize. Somewhat richer moisture (with dewpoints in the mid 60s F) may advect northward into eastern NC Tuesday evening into the overnight, as low-level flow veers and strengthens some in response to the deepening cyclone near the Mid Atlantic coast. Some uptick in the tornado/wind threat is possible over eastern NC and the Outer Banks as this occurs, though uncertainty remains high regarding evolution of the upper trough (described above) and strength of large-scale ascent across the region during the overnight period. ..Dean.. 11/20/2023 Read more

SPC Nov 20, 2023 0700 UTC Day 2 Convective Outlook

1 year 8 months ago
SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CST Mon Nov 20 2023 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS A SMALL PART OF SOUTH AL AND THE FL PANHANDLE... ...SUMMARY... A couple tornadoes are possible across parts of south Alabama into the Florida Panhandle, mainly during the morning and early afternoon. Locally damaging winds and perhaps a couple brief tornadoes will also be possible from Georgia into the Carolinas Tuesday afternoon into Tuesday night. ...Synopsis... A vigorous mid/upper-level low is forecast to evolve into an open wave on Tuesday as it moves toward the lower Great Lakes and Northeast through the day. The related surface cyclone will take a similar track, with some weakening expected as it becomes increasingly displaced from the effective warm sector. A trailing cold front will continue to move through parts of the Southeast. One or more surface waves may develop along the effective warm front, with most guidance depicting consolidation of a surface cyclone near or off of the Mid Atlantic coast by Wednesday morning. Guidance continues to vary substantially with regard to large-scale trough evolution in the wake of the departing midlevel low, with the GFS (and now the 20/00Z ECMWF) continuing to amplify a shortwave near the Ozarks/lower MS Valley vicinity, while other guidance maintains a broad positively tilted trough that gradually moves eastward toward the Atlantic Coast. ...Parts of AL/GA and the FL Panhandle... While the primary surface cyclone will continue moving away from the region on Tuesday, convection will likely persist through the day within a confluent regime along/ahead of the front across parts of AL and FL Panhandle, and eventually move into parts of GA. Generally weak instability (with MLCAPE generally less than 500 J/kg away from the immediate coast) may tend to limit storm intensity, but favorable moisture and deep-layer shear will continue to support the potential for at least transient supercell structures. 0-1 km SRH generally in the 150-250 m2/s2 range will support some tornado threat where sufficient destabilization can occur. The threat may peak early in the day across south AL and the FL Panhandle, in association with any supercells that develop during the D1/Monday period and persist into Tuesday morning. A small Slight Risk has been included across this area, as a continuation of the threat from late on D1/Monday. Some threat for locally damaging gusts and/or a brief tornado may persist into the afternoon across parts of GA, in areas where modest diurnal heating can augment generally weak instability. ...Carolinas... A warm front is forecast to move northward across the Carolinas during the day, accompanied by low 60s F dewpoints. While wind profiles will become increasingly favorable for organized convection, instability is expected to remain very weak through the afternoon, due to weak lapse rates and rather widespread cloudiness and precipitation. There is some potential for an organized frontal band to develop and move eastward, which could pose a damaging-wind threat given the expected strength of low-level flow. A conditional Marginal Risk has been included for this threat, though the areal coverage of the convectively enhanced gust threat remains uncertain, due to diminishing instability with northward extent. Strong low-level shear could also support a brief tornado threat if pockets of somewhat greater instability can materialize. Somewhat richer moisture (with dewpoints in the mid 60s F) may advect northward into eastern NC Tuesday evening into the overnight, as low-level flow veers and strengthens some in response to the deepening cyclone near the Mid Atlantic coast. Some uptick in the tornado/wind threat is possible over eastern NC and the Outer Banks as this occurs, though uncertainty remains high regarding evolution of the upper trough (described above) and strength of large-scale ascent across the region during the overnight period. ..Dean.. 11/20/2023 Read more

SPC Nov 20, 2023 0700 UTC Day 2 Convective Outlook

1 year 8 months ago
SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CST Mon Nov 20 2023 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS A SMALL PART OF SOUTH AL AND THE FL PANHANDLE... ...SUMMARY... A couple tornadoes are possible across parts of south Alabama into the Florida Panhandle, mainly during the morning and early afternoon. Locally damaging winds and perhaps a couple brief tornadoes will also be possible from Georgia into the Carolinas Tuesday afternoon into Tuesday night. ...Synopsis... A vigorous mid/upper-level low is forecast to evolve into an open wave on Tuesday as it moves toward the lower Great Lakes and Northeast through the day. The related surface cyclone will take a similar track, with some weakening expected as it becomes increasingly displaced from the effective warm sector. A trailing cold front will continue to move through parts of the Southeast. One or more surface waves may develop along the effective warm front, with most guidance depicting consolidation of a surface cyclone near or off of the Mid Atlantic coast by Wednesday morning. Guidance continues to vary substantially with regard to large-scale trough evolution in the wake of the departing midlevel low, with the GFS (and now the 20/00Z ECMWF) continuing to amplify a shortwave near the Ozarks/lower MS Valley vicinity, while other guidance maintains a broad positively tilted trough that gradually moves eastward toward the Atlantic Coast. ...Parts of AL/GA and the FL Panhandle... While the primary surface cyclone will continue moving away from the region on Tuesday, convection will likely persist through the day within a confluent regime along/ahead of the front across parts of AL and FL Panhandle, and eventually move into parts of GA. Generally weak instability (with MLCAPE generally less than 500 J/kg away from the immediate coast) may tend to limit storm intensity, but favorable moisture and deep-layer shear will continue to support the potential for at least transient supercell structures. 0-1 km SRH generally in the 150-250 m2/s2 range will support some tornado threat where sufficient destabilization can occur. The threat may peak early in the day across south AL and the FL Panhandle, in association with any supercells that develop during the D1/Monday period and persist into Tuesday morning. A small Slight Risk has been included across this area, as a continuation of the threat from late on D1/Monday. Some threat for locally damaging gusts and/or a brief tornado may persist into the afternoon across parts of GA, in areas where modest diurnal heating can augment generally weak instability. ...Carolinas... A warm front is forecast to move northward across the Carolinas during the day, accompanied by low 60s F dewpoints. While wind profiles will become increasingly favorable for organized convection, instability is expected to remain very weak through the afternoon, due to weak lapse rates and rather widespread cloudiness and precipitation. There is some potential for an organized frontal band to develop and move eastward, which could pose a damaging-wind threat given the expected strength of low-level flow. A conditional Marginal Risk has been included for this threat, though the areal coverage of the convectively enhanced gust threat remains uncertain, due to diminishing instability with northward extent. Strong low-level shear could also support a brief tornado threat if pockets of somewhat greater instability can materialize. Somewhat richer moisture (with dewpoints in the mid 60s F) may advect northward into eastern NC Tuesday evening into the overnight, as low-level flow veers and strengthens some in response to the deepening cyclone near the Mid Atlantic coast. Some uptick in the tornado/wind threat is possible over eastern NC and the Outer Banks as this occurs, though uncertainty remains high regarding evolution of the upper trough (described above) and strength of large-scale ascent across the region during the overnight period. ..Dean.. 11/20/2023 Read more

SPC Nov 20, 2023 0700 UTC Day 2 Convective Outlook

1 year 8 months ago
SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CST Mon Nov 20 2023 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS A SMALL PART OF SOUTH AL AND THE FL PANHANDLE... ...SUMMARY... A couple tornadoes are possible across parts of south Alabama into the Florida Panhandle, mainly during the morning and early afternoon. Locally damaging winds and perhaps a couple brief tornadoes will also be possible from Georgia into the Carolinas Tuesday afternoon into Tuesday night. ...Synopsis... A vigorous mid/upper-level low is forecast to evolve into an open wave on Tuesday as it moves toward the lower Great Lakes and Northeast through the day. The related surface cyclone will take a similar track, with some weakening expected as it becomes increasingly displaced from the effective warm sector. A trailing cold front will continue to move through parts of the Southeast. One or more surface waves may develop along the effective warm front, with most guidance depicting consolidation of a surface cyclone near or off of the Mid Atlantic coast by Wednesday morning. Guidance continues to vary substantially with regard to large-scale trough evolution in the wake of the departing midlevel low, with the GFS (and now the 20/00Z ECMWF) continuing to amplify a shortwave near the Ozarks/lower MS Valley vicinity, while other guidance maintains a broad positively tilted trough that gradually moves eastward toward the Atlantic Coast. ...Parts of AL/GA and the FL Panhandle... While the primary surface cyclone will continue moving away from the region on Tuesday, convection will likely persist through the day within a confluent regime along/ahead of the front across parts of AL and FL Panhandle, and eventually move into parts of GA. Generally weak instability (with MLCAPE generally less than 500 J/kg away from the immediate coast) may tend to limit storm intensity, but favorable moisture and deep-layer shear will continue to support the potential for at least transient supercell structures. 0-1 km SRH generally in the 150-250 m2/s2 range will support some tornado threat where sufficient destabilization can occur. The threat may peak early in the day across south AL and the FL Panhandle, in association with any supercells that develop during the D1/Monday period and persist into Tuesday morning. A small Slight Risk has been included across this area, as a continuation of the threat from late on D1/Monday. Some threat for locally damaging gusts and/or a brief tornado may persist into the afternoon across parts of GA, in areas where modest diurnal heating can augment generally weak instability. ...Carolinas... A warm front is forecast to move northward across the Carolinas during the day, accompanied by low 60s F dewpoints. While wind profiles will become increasingly favorable for organized convection, instability is expected to remain very weak through the afternoon, due to weak lapse rates and rather widespread cloudiness and precipitation. There is some potential for an organized frontal band to develop and move eastward, which could pose a damaging-wind threat given the expected strength of low-level flow. A conditional Marginal Risk has been included for this threat, though the areal coverage of the convectively enhanced gust threat remains uncertain, due to diminishing instability with northward extent. Strong low-level shear could also support a brief tornado threat if pockets of somewhat greater instability can materialize. Somewhat richer moisture (with dewpoints in the mid 60s F) may advect northward into eastern NC Tuesday evening into the overnight, as low-level flow veers and strengthens some in response to the deepening cyclone near the Mid Atlantic coast. Some uptick in the tornado/wind threat is possible over eastern NC and the Outer Banks as this occurs, though uncertainty remains high regarding evolution of the upper trough (described above) and strength of large-scale ascent across the region during the overnight period. ..Dean.. 11/20/2023 Read more

SPC MD 2271

1 year 8 months ago
MD 2271 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF CENTRAL/SOUTHEAST OK
Mesoscale Discussion 2271 NWS Storm Prediction Center Norman OK 1228 AM CST Mon Nov 20 2023 Areas affected...portions of central/southeast OK Concerning...Severe potential...Watch unlikely Valid 200628Z - 200830Z Probability of Watch Issuance...5 percent SUMMARY...A couple of stronger thunderstorms may produce half-inch to nearly one-inch diameter hail over the next few hours. A severe thunderstorm watch is not expected. DISCUSSION...A couple of stronger thunderstorms have develop late this evening over central OK. This activity is on the margins of stronger 0-6 km shear focused along the Red River. KTLX VWP data indicated around 35 kt effective-shear magnitudes. Modified 00z RAOB from OUN suggests this activity is rooted between 850 and 700 mb and on the nose of steeper midlevel lapse rates overspreading the area from the west. These steeper midlevel lapse rates are contributing to weak instability, with generally 250-500 J/kg MLCAPE noted in latest mesoanalysis. While there is some modest elongation of the hodograph based on KTLX VWP data, given the overall thermodynamic environment, any stronger convection will likely only be maintained briefly. This stronger activity may produce nickel to briefly quarter-size hail for a few hours into the overnight hours. A severe thunderstorm watch is not expected given the marginal nature of the threat. ..Leitman/Edwards.. 11/20/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TSA...OUN... LAT...LON 35039740 35429688 35629583 35599508 35429467 35029462 34749472 34679484 34459554 34309619 34379701 34589727 35039740 Read more

SPC Nov 20, 2023 0600 UTC Day 1 Convective Outlook

1 year 8 months ago
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1200 AM CST Mon Nov 20 2023 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF FAR EAST TEXAS...CENTRAL LOUISIANA AND SOUTHWEST MISSISSIPPI... ...SUMMARY... Severe thunderstorms are likely this afternoon into tonight from east Texas, into parts of the Lower-Mississippi Valley, and Southeast States. Damaging winds and several tornadoes, a few of which may be strong, will be the primary hazards. Though damaging winds and some large hail are also possible. ...Synopsis... A broad positively tilted mid-level trough and jet streak over the southern Rockies is forecast to consolidate and strengthen rapidly into an upper low moving over the Southern Plains and the lower Mississippi Valley by late tonight. Several more neutral to negatively tilted shortwave perturbations embedded within the 80-90 kt jet streak will round the base of the trough and eject over the ArkLaTex and Southeast ahead of the main trough this afternoon. Broad diffluence and strong forcing for ascent will aid a surface low over OK as it moves northeastward toward the Mississippi River tonight. Strong low-level mass response ahead of the trough and the surface low should draw a warm front with rich low-level moisture (dewpoints in the 60s F) as far north as the MS/TN border. While mid-level lapse rates are modest, strong differential thermal advection and ascent should allow for the development of weak to moderate buoyancy sufficient for scattered severe storms over parts of the ArklaTex and Southeast states this afternoon into tonight. ...East TX into the lower Mississippi Valley... A complex convective evolution is expected today with widespread showers and thunderstorms likely to be ongoing north and east of the surface warm front across eastern OK, AR and parts of northeast TX at the start of the period. Isentropic ascent should remain strong through the morning hours with weak showers and broken to overcast skies likely throughout the warm sector. While this will likely inhibit surface heating to some degree, a few cloud breaks and low-level warm advection along a pre-frontal confluence axis in east TX should allow for weak to moderate destabilization and scattered storm development by mid morning to early afternoon. Veered surface flow with relatively weak shear and high RH in the low-levels suggests a messy storm evolution with early updrafts. However, strong line-normal mid and upper-level shear components should allow for the gradual intensification of individual supercell structures within a broader cluster or broken line ahead of the surface cold front across east-central TX. Albeit gradual, owing to modest low and mid-level lapse rates, the maturation of these storms through the mid to later afternoon will eventually overlap with a strongly sheared-low-level air mass as the main upper jet ejects over parts of far east TX, southern AR, and LA. 0-500m SRH of 100-150 m2/s2 and STP values of 2-3 will likely support strong low-level mesocyclones with the potential for tornadoes, some of which could be strong. These storms should continue eastward through the evening hours with a risk for tornadoes before gradual upscale growth into a loose QLCS increases the potential for damaging winds over central and eastern MS into western AL. Across parts of eastern AR into western/central TN and northern MS/AL, low-level destabilization appears much less favorable with multiple rounds of warm advection precipitation ahead of the surface low and main trough. A few model solutions bring the warm front far enough north to generate some positive near-surface buoyancy immediately ahead of the cold front. A fine-line QLCS may evolve with a low-end risk for damaging wind gusts given mixing of the strong background wind field to the surface. ...Southern AL and Gulf Coast tonight... As the warm front lifts north over parts of southeastern LA and southern MS this afternoon and evening, rich Gulf moisture will move quickly inland beneath a 30-40 kt low-level jet. While it is uncertain if storms can develop given modest forcing, a few supercells may evolve within the warm sector and track northeastward toward the strongly sheared frontal zone. A few tornadoes could develop in the evening hours ahead of the main band of convection farther west. Later tonight, the storms ahead of the cold front should gradually coalesce into a QLCS as the front shifts eastward. With strong low-level wind fields and at least some buoyancy remaining in place, damaging gusts and isolated tornadoes are possible well into the overnight hours across southeastern MS, southwest AL and possibly the western FL Panhandle. However, confidence in the eastward extent of the severe risk will depend greatly on the onshore destabilization which, given the diurnal timing, is not a guarantee. ..Lyons/Darrow.. 11/20/2023 Read more

SPC Nov 20, 2023 0600 UTC Day 1 Convective Outlook

1 year 8 months ago
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1200 AM CST Mon Nov 20 2023 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF FAR EAST TEXAS...CENTRAL LOUISIANA AND SOUTHWEST MISSISSIPPI... ...SUMMARY... Severe thunderstorms are likely this afternoon into tonight from east Texas, into parts of the Lower-Mississippi Valley, and Southeast States. Damaging winds and several tornadoes, a few of which may be strong, will be the primary hazards. Though damaging winds and some large hail are also possible. ...Synopsis... A broad positively tilted mid-level trough and jet streak over the southern Rockies is forecast to consolidate and strengthen rapidly into an upper low moving over the Southern Plains and the lower Mississippi Valley by late tonight. Several more neutral to negatively tilted shortwave perturbations embedded within the 80-90 kt jet streak will round the base of the trough and eject over the ArkLaTex and Southeast ahead of the main trough this afternoon. Broad diffluence and strong forcing for ascent will aid a surface low over OK as it moves northeastward toward the Mississippi River tonight. Strong low-level mass response ahead of the trough and the surface low should draw a warm front with rich low-level moisture (dewpoints in the 60s F) as far north as the MS/TN border. While mid-level lapse rates are modest, strong differential thermal advection and ascent should allow for the development of weak to moderate buoyancy sufficient for scattered severe storms over parts of the ArklaTex and Southeast states this afternoon into tonight. ...East TX into the lower Mississippi Valley... A complex convective evolution is expected today with widespread showers and thunderstorms likely to be ongoing north and east of the surface warm front across eastern OK, AR and parts of northeast TX at the start of the period. Isentropic ascent should remain strong through the morning hours with weak showers and broken to overcast skies likely throughout the warm sector. While this will likely inhibit surface heating to some degree, a few cloud breaks and low-level warm advection along a pre-frontal confluence axis in east TX should allow for weak to moderate destabilization and scattered storm development by mid morning to early afternoon. Veered surface flow with relatively weak shear and high RH in the low-levels suggests a messy storm evolution with early updrafts. However, strong line-normal mid and upper-level shear components should allow for the gradual intensification of individual supercell structures within a broader cluster or broken line ahead of the surface cold front across east-central TX. Albeit gradual, owing to modest low and mid-level lapse rates, the maturation of these storms through the mid to later afternoon will eventually overlap with a strongly sheared-low-level air mass as the main upper jet ejects over parts of far east TX, southern AR, and LA. 0-500m SRH of 100-150 m2/s2 and STP values of 2-3 will likely support strong low-level mesocyclones with the potential for tornadoes, some of which could be strong. These storms should continue eastward through the evening hours with a risk for tornadoes before gradual upscale growth into a loose QLCS increases the potential for damaging winds over central and eastern MS into western AL. Across parts of eastern AR into western/central TN and northern MS/AL, low-level destabilization appears much less favorable with multiple rounds of warm advection precipitation ahead of the surface low and main trough. A few model solutions bring the warm front far enough north to generate some positive near-surface buoyancy immediately ahead of the cold front. A fine-line QLCS may evolve with a low-end risk for damaging wind gusts given mixing of the strong background wind field to the surface. ...Southern AL and Gulf Coast tonight... As the warm front lifts north over parts of southeastern LA and southern MS this afternoon and evening, rich Gulf moisture will move quickly inland beneath a 30-40 kt low-level jet. While it is uncertain if storms can develop given modest forcing, a few supercells may evolve within the warm sector and track northeastward toward the strongly sheared frontal zone. A few tornadoes could develop in the evening hours ahead of the main band of convection farther west. Later tonight, the storms ahead of the cold front should gradually coalesce into a QLCS as the front shifts eastward. With strong low-level wind fields and at least some buoyancy remaining in place, damaging gusts and isolated tornadoes are possible well into the overnight hours across southeastern MS, southwest AL and possibly the western FL Panhandle. However, confidence in the eastward extent of the severe risk will depend greatly on the onshore destabilization which, given the diurnal timing, is not a guarantee. ..Lyons/Darrow.. 11/20/2023 Read more

SPC Nov 20, 2023 0600 UTC Day 1 Convective Outlook

1 year 8 months ago
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1200 AM CST Mon Nov 20 2023 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF FAR EAST TEXAS...CENTRAL LOUISIANA AND SOUTHWEST MISSISSIPPI... ...SUMMARY... Severe thunderstorms are likely this afternoon into tonight from east Texas, into parts of the Lower-Mississippi Valley, and Southeast States. Damaging winds and several tornadoes, a few of which may be strong, will be the primary hazards. Though damaging winds and some large hail are also possible. ...Synopsis... A broad positively tilted mid-level trough and jet streak over the southern Rockies is forecast to consolidate and strengthen rapidly into an upper low moving over the Southern Plains and the lower Mississippi Valley by late tonight. Several more neutral to negatively tilted shortwave perturbations embedded within the 80-90 kt jet streak will round the base of the trough and eject over the ArkLaTex and Southeast ahead of the main trough this afternoon. Broad diffluence and strong forcing for ascent will aid a surface low over OK as it moves northeastward toward the Mississippi River tonight. Strong low-level mass response ahead of the trough and the surface low should draw a warm front with rich low-level moisture (dewpoints in the 60s F) as far north as the MS/TN border. While mid-level lapse rates are modest, strong differential thermal advection and ascent should allow for the development of weak to moderate buoyancy sufficient for scattered severe storms over parts of the ArklaTex and Southeast states this afternoon into tonight. ...East TX into the lower Mississippi Valley... A complex convective evolution is expected today with widespread showers and thunderstorms likely to be ongoing north and east of the surface warm front across eastern OK, AR and parts of northeast TX at the start of the period. Isentropic ascent should remain strong through the morning hours with weak showers and broken to overcast skies likely throughout the warm sector. While this will likely inhibit surface heating to some degree, a few cloud breaks and low-level warm advection along a pre-frontal confluence axis in east TX should allow for weak to moderate destabilization and scattered storm development by mid morning to early afternoon. Veered surface flow with relatively weak shear and high RH in the low-levels suggests a messy storm evolution with early updrafts. However, strong line-normal mid and upper-level shear components should allow for the gradual intensification of individual supercell structures within a broader cluster or broken line ahead of the surface cold front across east-central TX. Albeit gradual, owing to modest low and mid-level lapse rates, the maturation of these storms through the mid to later afternoon will eventually overlap with a strongly sheared-low-level air mass as the main upper jet ejects over parts of far east TX, southern AR, and LA. 0-500m SRH of 100-150 m2/s2 and STP values of 2-3 will likely support strong low-level mesocyclones with the potential for tornadoes, some of which could be strong. These storms should continue eastward through the evening hours with a risk for tornadoes before gradual upscale growth into a loose QLCS increases the potential for damaging winds over central and eastern MS into western AL. Across parts of eastern AR into western/central TN and northern MS/AL, low-level destabilization appears much less favorable with multiple rounds of warm advection precipitation ahead of the surface low and main trough. A few model solutions bring the warm front far enough north to generate some positive near-surface buoyancy immediately ahead of the cold front. A fine-line QLCS may evolve with a low-end risk for damaging wind gusts given mixing of the strong background wind field to the surface. ...Southern AL and Gulf Coast tonight... As the warm front lifts north over parts of southeastern LA and southern MS this afternoon and evening, rich Gulf moisture will move quickly inland beneath a 30-40 kt low-level jet. While it is uncertain if storms can develop given modest forcing, a few supercells may evolve within the warm sector and track northeastward toward the strongly sheared frontal zone. A few tornadoes could develop in the evening hours ahead of the main band of convection farther west. Later tonight, the storms ahead of the cold front should gradually coalesce into a QLCS as the front shifts eastward. With strong low-level wind fields and at least some buoyancy remaining in place, damaging gusts and isolated tornadoes are possible well into the overnight hours across southeastern MS, southwest AL and possibly the western FL Panhandle. However, confidence in the eastward extent of the severe risk will depend greatly on the onshore destabilization which, given the diurnal timing, is not a guarantee. ..Lyons/Darrow.. 11/20/2023 Read more

SPC Nov 20, 2023 0600 UTC Day 1 Convective Outlook

1 year 8 months ago
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1200 AM CST Mon Nov 20 2023 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF FAR EAST TEXAS...CENTRAL LOUISIANA AND SOUTHWEST MISSISSIPPI... ...SUMMARY... Severe thunderstorms are likely this afternoon into tonight from east Texas, into parts of the Lower-Mississippi Valley, and Southeast States. Damaging winds and several tornadoes, a few of which may be strong, will be the primary hazards. Though damaging winds and some large hail are also possible. ...Synopsis... A broad positively tilted mid-level trough and jet streak over the southern Rockies is forecast to consolidate and strengthen rapidly into an upper low moving over the Southern Plains and the lower Mississippi Valley by late tonight. Several more neutral to negatively tilted shortwave perturbations embedded within the 80-90 kt jet streak will round the base of the trough and eject over the ArkLaTex and Southeast ahead of the main trough this afternoon. Broad diffluence and strong forcing for ascent will aid a surface low over OK as it moves northeastward toward the Mississippi River tonight. Strong low-level mass response ahead of the trough and the surface low should draw a warm front with rich low-level moisture (dewpoints in the 60s F) as far north as the MS/TN border. While mid-level lapse rates are modest, strong differential thermal advection and ascent should allow for the development of weak to moderate buoyancy sufficient for scattered severe storms over parts of the ArklaTex and Southeast states this afternoon into tonight. ...East TX into the lower Mississippi Valley... A complex convective evolution is expected today with widespread showers and thunderstorms likely to be ongoing north and east of the surface warm front across eastern OK, AR and parts of northeast TX at the start of the period. Isentropic ascent should remain strong through the morning hours with weak showers and broken to overcast skies likely throughout the warm sector. While this will likely inhibit surface heating to some degree, a few cloud breaks and low-level warm advection along a pre-frontal confluence axis in east TX should allow for weak to moderate destabilization and scattered storm development by mid morning to early afternoon. Veered surface flow with relatively weak shear and high RH in the low-levels suggests a messy storm evolution with early updrafts. However, strong line-normal mid and upper-level shear components should allow for the gradual intensification of individual supercell structures within a broader cluster or broken line ahead of the surface cold front across east-central TX. Albeit gradual, owing to modest low and mid-level lapse rates, the maturation of these storms through the mid to later afternoon will eventually overlap with a strongly sheared-low-level air mass as the main upper jet ejects over parts of far east TX, southern AR, and LA. 0-500m SRH of 100-150 m2/s2 and STP values of 2-3 will likely support strong low-level mesocyclones with the potential for tornadoes, some of which could be strong. These storms should continue eastward through the evening hours with a risk for tornadoes before gradual upscale growth into a loose QLCS increases the potential for damaging winds over central and eastern MS into western AL. Across parts of eastern AR into western/central TN and northern MS/AL, low-level destabilization appears much less favorable with multiple rounds of warm advection precipitation ahead of the surface low and main trough. A few model solutions bring the warm front far enough north to generate some positive near-surface buoyancy immediately ahead of the cold front. A fine-line QLCS may evolve with a low-end risk for damaging wind gusts given mixing of the strong background wind field to the surface. ...Southern AL and Gulf Coast tonight... As the warm front lifts north over parts of southeastern LA and southern MS this afternoon and evening, rich Gulf moisture will move quickly inland beneath a 30-40 kt low-level jet. While it is uncertain if storms can develop given modest forcing, a few supercells may evolve within the warm sector and track northeastward toward the strongly sheared frontal zone. A few tornadoes could develop in the evening hours ahead of the main band of convection farther west. Later tonight, the storms ahead of the cold front should gradually coalesce into a QLCS as the front shifts eastward. With strong low-level wind fields and at least some buoyancy remaining in place, damaging gusts and isolated tornadoes are possible well into the overnight hours across southeastern MS, southwest AL and possibly the western FL Panhandle. However, confidence in the eastward extent of the severe risk will depend greatly on the onshore destabilization which, given the diurnal timing, is not a guarantee. ..Lyons/Darrow.. 11/20/2023 Read more

SPC Nov 20, 2023 0600 UTC Day 1 Convective Outlook

1 year 8 months ago
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1200 AM CST Mon Nov 20 2023 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF FAR EAST TEXAS...CENTRAL LOUISIANA AND SOUTHWEST MISSISSIPPI... ...SUMMARY... Severe thunderstorms are likely this afternoon into tonight from east Texas, into parts of the Lower-Mississippi Valley, and Southeast States. Damaging winds and several tornadoes, a few of which may be strong, will be the primary hazards. Though damaging winds and some large hail are also possible. ...Synopsis... A broad positively tilted mid-level trough and jet streak over the southern Rockies is forecast to consolidate and strengthen rapidly into an upper low moving over the Southern Plains and the lower Mississippi Valley by late tonight. Several more neutral to negatively tilted shortwave perturbations embedded within the 80-90 kt jet streak will round the base of the trough and eject over the ArkLaTex and Southeast ahead of the main trough this afternoon. Broad diffluence and strong forcing for ascent will aid a surface low over OK as it moves northeastward toward the Mississippi River tonight. Strong low-level mass response ahead of the trough and the surface low should draw a warm front with rich low-level moisture (dewpoints in the 60s F) as far north as the MS/TN border. While mid-level lapse rates are modest, strong differential thermal advection and ascent should allow for the development of weak to moderate buoyancy sufficient for scattered severe storms over parts of the ArklaTex and Southeast states this afternoon into tonight. ...East TX into the lower Mississippi Valley... A complex convective evolution is expected today with widespread showers and thunderstorms likely to be ongoing north and east of the surface warm front across eastern OK, AR and parts of northeast TX at the start of the period. Isentropic ascent should remain strong through the morning hours with weak showers and broken to overcast skies likely throughout the warm sector. While this will likely inhibit surface heating to some degree, a few cloud breaks and low-level warm advection along a pre-frontal confluence axis in east TX should allow for weak to moderate destabilization and scattered storm development by mid morning to early afternoon. Veered surface flow with relatively weak shear and high RH in the low-levels suggests a messy storm evolution with early updrafts. However, strong line-normal mid and upper-level shear components should allow for the gradual intensification of individual supercell structures within a broader cluster or broken line ahead of the surface cold front across east-central TX. Albeit gradual, owing to modest low and mid-level lapse rates, the maturation of these storms through the mid to later afternoon will eventually overlap with a strongly sheared-low-level air mass as the main upper jet ejects over parts of far east TX, southern AR, and LA. 0-500m SRH of 100-150 m2/s2 and STP values of 2-3 will likely support strong low-level mesocyclones with the potential for tornadoes, some of which could be strong. These storms should continue eastward through the evening hours with a risk for tornadoes before gradual upscale growth into a loose QLCS increases the potential for damaging winds over central and eastern MS into western AL. Across parts of eastern AR into western/central TN and northern MS/AL, low-level destabilization appears much less favorable with multiple rounds of warm advection precipitation ahead of the surface low and main trough. A few model solutions bring the warm front far enough north to generate some positive near-surface buoyancy immediately ahead of the cold front. A fine-line QLCS may evolve with a low-end risk for damaging wind gusts given mixing of the strong background wind field to the surface. ...Southern AL and Gulf Coast tonight... As the warm front lifts north over parts of southeastern LA and southern MS this afternoon and evening, rich Gulf moisture will move quickly inland beneath a 30-40 kt low-level jet. While it is uncertain if storms can develop given modest forcing, a few supercells may evolve within the warm sector and track northeastward toward the strongly sheared frontal zone. A few tornadoes could develop in the evening hours ahead of the main band of convection farther west. Later tonight, the storms ahead of the cold front should gradually coalesce into a QLCS as the front shifts eastward. With strong low-level wind fields and at least some buoyancy remaining in place, damaging gusts and isolated tornadoes are possible well into the overnight hours across southeastern MS, southwest AL and possibly the western FL Panhandle. However, confidence in the eastward extent of the severe risk will depend greatly on the onshore destabilization which, given the diurnal timing, is not a guarantee. ..Lyons/Darrow.. 11/20/2023 Read more

SPC Nov 20, 2023 0600 UTC Day 1 Convective Outlook

1 year 8 months ago
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1200 AM CST Mon Nov 20 2023 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF FAR EAST TEXAS...CENTRAL LOUISIANA AND SOUTHWEST MISSISSIPPI... ...SUMMARY... Severe thunderstorms are likely this afternoon into tonight from east Texas, into parts of the Lower-Mississippi Valley, and Southeast States. Damaging winds and several tornadoes, a few of which may be strong, will be the primary hazards. Though damaging winds and some large hail are also possible. ...Synopsis... A broad positively tilted mid-level trough and jet streak over the southern Rockies is forecast to consolidate and strengthen rapidly into an upper low moving over the Southern Plains and the lower Mississippi Valley by late tonight. Several more neutral to negatively tilted shortwave perturbations embedded within the 80-90 kt jet streak will round the base of the trough and eject over the ArkLaTex and Southeast ahead of the main trough this afternoon. Broad diffluence and strong forcing for ascent will aid a surface low over OK as it moves northeastward toward the Mississippi River tonight. Strong low-level mass response ahead of the trough and the surface low should draw a warm front with rich low-level moisture (dewpoints in the 60s F) as far north as the MS/TN border. While mid-level lapse rates are modest, strong differential thermal advection and ascent should allow for the development of weak to moderate buoyancy sufficient for scattered severe storms over parts of the ArklaTex and Southeast states this afternoon into tonight. ...East TX into the lower Mississippi Valley... A complex convective evolution is expected today with widespread showers and thunderstorms likely to be ongoing north and east of the surface warm front across eastern OK, AR and parts of northeast TX at the start of the period. Isentropic ascent should remain strong through the morning hours with weak showers and broken to overcast skies likely throughout the warm sector. While this will likely inhibit surface heating to some degree, a few cloud breaks and low-level warm advection along a pre-frontal confluence axis in east TX should allow for weak to moderate destabilization and scattered storm development by mid morning to early afternoon. Veered surface flow with relatively weak shear and high RH in the low-levels suggests a messy storm evolution with early updrafts. However, strong line-normal mid and upper-level shear components should allow for the gradual intensification of individual supercell structures within a broader cluster or broken line ahead of the surface cold front across east-central TX. Albeit gradual, owing to modest low and mid-level lapse rates, the maturation of these storms through the mid to later afternoon will eventually overlap with a strongly sheared-low-level air mass as the main upper jet ejects over parts of far east TX, southern AR, and LA. 0-500m SRH of 100-150 m2/s2 and STP values of 2-3 will likely support strong low-level mesocyclones with the potential for tornadoes, some of which could be strong. These storms should continue eastward through the evening hours with a risk for tornadoes before gradual upscale growth into a loose QLCS increases the potential for damaging winds over central and eastern MS into western AL. Across parts of eastern AR into western/central TN and northern MS/AL, low-level destabilization appears much less favorable with multiple rounds of warm advection precipitation ahead of the surface low and main trough. A few model solutions bring the warm front far enough north to generate some positive near-surface buoyancy immediately ahead of the cold front. A fine-line QLCS may evolve with a low-end risk for damaging wind gusts given mixing of the strong background wind field to the surface. ...Southern AL and Gulf Coast tonight... As the warm front lifts north over parts of southeastern LA and southern MS this afternoon and evening, rich Gulf moisture will move quickly inland beneath a 30-40 kt low-level jet. While it is uncertain if storms can develop given modest forcing, a few supercells may evolve within the warm sector and track northeastward toward the strongly sheared frontal zone. A few tornadoes could develop in the evening hours ahead of the main band of convection farther west. Later tonight, the storms ahead of the cold front should gradually coalesce into a QLCS as the front shifts eastward. With strong low-level wind fields and at least some buoyancy remaining in place, damaging gusts and isolated tornadoes are possible well into the overnight hours across southeastern MS, southwest AL and possibly the western FL Panhandle. However, confidence in the eastward extent of the severe risk will depend greatly on the onshore destabilization which, given the diurnal timing, is not a guarantee. ..Lyons/Darrow.. 11/20/2023 Read more

SPC Nov 20, 2023 0600 UTC Day 1 Convective Outlook

1 year 8 months ago
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1200 AM CST Mon Nov 20 2023 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF FAR EAST TEXAS...CENTRAL LOUISIANA AND SOUTHWEST MISSISSIPPI... ...SUMMARY... Severe thunderstorms are likely this afternoon into tonight from east Texas, into parts of the Lower-Mississippi Valley, and Southeast States. Damaging winds and several tornadoes, a few of which may be strong, will be the primary hazards. Though damaging winds and some large hail are also possible. ...Synopsis... A broad positively tilted mid-level trough and jet streak over the southern Rockies is forecast to consolidate and strengthen rapidly into an upper low moving over the Southern Plains and the lower Mississippi Valley by late tonight. Several more neutral to negatively tilted shortwave perturbations embedded within the 80-90 kt jet streak will round the base of the trough and eject over the ArkLaTex and Southeast ahead of the main trough this afternoon. Broad diffluence and strong forcing for ascent will aid a surface low over OK as it moves northeastward toward the Mississippi River tonight. Strong low-level mass response ahead of the trough and the surface low should draw a warm front with rich low-level moisture (dewpoints in the 60s F) as far north as the MS/TN border. While mid-level lapse rates are modest, strong differential thermal advection and ascent should allow for the development of weak to moderate buoyancy sufficient for scattered severe storms over parts of the ArklaTex and Southeast states this afternoon into tonight. ...East TX into the lower Mississippi Valley... A complex convective evolution is expected today with widespread showers and thunderstorms likely to be ongoing north and east of the surface warm front across eastern OK, AR and parts of northeast TX at the start of the period. Isentropic ascent should remain strong through the morning hours with weak showers and broken to overcast skies likely throughout the warm sector. While this will likely inhibit surface heating to some degree, a few cloud breaks and low-level warm advection along a pre-frontal confluence axis in east TX should allow for weak to moderate destabilization and scattered storm development by mid morning to early afternoon. Veered surface flow with relatively weak shear and high RH in the low-levels suggests a messy storm evolution with early updrafts. However, strong line-normal mid and upper-level shear components should allow for the gradual intensification of individual supercell structures within a broader cluster or broken line ahead of the surface cold front across east-central TX. Albeit gradual, owing to modest low and mid-level lapse rates, the maturation of these storms through the mid to later afternoon will eventually overlap with a strongly sheared-low-level air mass as the main upper jet ejects over parts of far east TX, southern AR, and LA. 0-500m SRH of 100-150 m2/s2 and STP values of 2-3 will likely support strong low-level mesocyclones with the potential for tornadoes, some of which could be strong. These storms should continue eastward through the evening hours with a risk for tornadoes before gradual upscale growth into a loose QLCS increases the potential for damaging winds over central and eastern MS into western AL. Across parts of eastern AR into western/central TN and northern MS/AL, low-level destabilization appears much less favorable with multiple rounds of warm advection precipitation ahead of the surface low and main trough. A few model solutions bring the warm front far enough north to generate some positive near-surface buoyancy immediately ahead of the cold front. A fine-line QLCS may evolve with a low-end risk for damaging wind gusts given mixing of the strong background wind field to the surface. ...Southern AL and Gulf Coast tonight... As the warm front lifts north over parts of southeastern LA and southern MS this afternoon and evening, rich Gulf moisture will move quickly inland beneath a 30-40 kt low-level jet. While it is uncertain if storms can develop given modest forcing, a few supercells may evolve within the warm sector and track northeastward toward the strongly sheared frontal zone. A few tornadoes could develop in the evening hours ahead of the main band of convection farther west. Later tonight, the storms ahead of the cold front should gradually coalesce into a QLCS as the front shifts eastward. With strong low-level wind fields and at least some buoyancy remaining in place, damaging gusts and isolated tornadoes are possible well into the overnight hours across southeastern MS, southwest AL and possibly the western FL Panhandle. However, confidence in the eastward extent of the severe risk will depend greatly on the onshore destabilization which, given the diurnal timing, is not a guarantee. ..Lyons/Darrow.. 11/20/2023 Read more