Severe Storms

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1011 AM CST Thu Dec 28 2023 Valid 281630Z - 291200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... No severe thunderstorms are forecast across the contiguous U.S. through tonight. A large upper low remains over the mid MS Valley today, with dry and stable conditions over the nation. Thunderstorms that earlier occurred near the FL Keys have move eastward and away from the coast. Other thunderstorms may occur off the coast of southeast New England tonight. But no organized thunderstorms are expected over the CONUS today or tonight. ..Hart/Supinie.. 12/28/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0637 AM CST Thu Dec 28 2023 Valid 281300Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... No severe thunderstorms are forecast across the contiguous U.S. through tonight. ...Synopsis/Discussion... A large, long-lived, nearly stacked, mid/upper-level low is evident in moisture-channel imagery over southern IL, with expansive cyclonic flow still apparent from the central/southern Rockies to the central/southern Appalachians, and the Great Lakes to the Gulf. The 500-mb low should wobble erratically through the period while taking a net eastward path up the lower Ohio Valley region. Just outside the southern rim of the gyre's closed isohypses, a couple southern-stream shortwave troughs are apparent over the central and southeastern Gulf. In response, and along a surface boundary that long has moved offshore from the Atlantic Coast, a frontal-wave low was analyzed at 11Z over the western Straits of Florida, with a warm front extending eastward, south of the Keys and across the Bahamas. The low and front should remain just south of the Keys into early afternoon, as the low ripples eastward to east-northeastward toward the area between Bimini and Andros Island. A small complex of thunderstorms has been apparent for a few hours near the low, moving eastward to the south of the Dry Tortugas and Marquesas Keys. The expanding northern fringes of this activity north of the low -- and/or additional convection developing in the warm-advection regime farther downshear and north of the Straits boundary -- will pose some lightning potential across the Keys and southernmost parts of the peninsula through midday. Around 100-300 J/kg elevated MUCAPE, occasionally extending into icing layers suitable for lightning, should be present north of the boundary, before the leading shortwave trough passes. ..Edwards/Dean.. 12/28/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0637 AM CST Thu Dec 28 2023 Valid 281300Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... No severe thunderstorms are forecast across the contiguous U.S. through tonight. ...Synopsis/Discussion... A large, long-lived, nearly stacked, mid/upper-level low is evident in moisture-channel imagery over southern IL, with expansive cyclonic flow still apparent from the central/southern Rockies to the central/southern Appalachians, and the Great Lakes to the Gulf. The 500-mb low should wobble erratically through the period while taking a net eastward path up the lower Ohio Valley region. Just outside the southern rim of the gyre's closed isohypses, a couple southern-stream shortwave troughs are apparent over the central and southeastern Gulf. In response, and along a surface boundary that long has moved offshore from the Atlantic Coast, a frontal-wave low was analyzed at 11Z over the western Straits of Florida, with a warm front extending eastward, south of the Keys and across the Bahamas. The low and front should remain just south of the Keys into early afternoon, as the low ripples eastward to east-northeastward toward the area between Bimini and Andros Island. A small complex of thunderstorms has been apparent for a few hours near the low, moving eastward to the south of the Dry Tortugas and Marquesas Keys. The expanding northern fringes of this activity north of the low -- and/or additional convection developing in the warm-advection regime farther downshear and north of the Straits boundary -- will pose some lightning potential across the Keys and southernmost parts of the peninsula through midday. Around 100-300 J/kg elevated MUCAPE, occasionally extending into icing layers suitable for lightning, should be present north of the boundary, before the leading shortwave trough passes. ..Edwards/Dean.. 12/28/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0637 AM CST Thu Dec 28 2023 Valid 281300Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... No severe thunderstorms are forecast across the contiguous U.S. through tonight. ...Synopsis/Discussion... A large, long-lived, nearly stacked, mid/upper-level low is evident in moisture-channel imagery over southern IL, with expansive cyclonic flow still apparent from the central/southern Rockies to the central/southern Appalachians, and the Great Lakes to the Gulf. The 500-mb low should wobble erratically through the period while taking a net eastward path up the lower Ohio Valley region. Just outside the southern rim of the gyre's closed isohypses, a couple southern-stream shortwave troughs are apparent over the central and southeastern Gulf. In response, and along a surface boundary that long has moved offshore from the Atlantic Coast, a frontal-wave low was analyzed at 11Z over the western Straits of Florida, with a warm front extending eastward, south of the Keys and across the Bahamas. The low and front should remain just south of the Keys into early afternoon, as the low ripples eastward to east-northeastward toward the area between Bimini and Andros Island. A small complex of thunderstorms has been apparent for a few hours near the low, moving eastward to the south of the Dry Tortugas and Marquesas Keys. The expanding northern fringes of this activity north of the low -- and/or additional convection developing in the warm-advection regime farther downshear and north of the Straits boundary -- will pose some lightning potential across the Keys and southernmost parts of the peninsula through midday. Around 100-300 J/kg elevated MUCAPE, occasionally extending into icing layers suitable for lightning, should be present north of the boundary, before the leading shortwave trough passes. ..Edwards/Dean.. 12/28/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0637 AM CST Thu Dec 28 2023 Valid 281300Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... No severe thunderstorms are forecast across the contiguous U.S. through tonight. ...Synopsis/Discussion... A large, long-lived, nearly stacked, mid/upper-level low is evident in moisture-channel imagery over southern IL, with expansive cyclonic flow still apparent from the central/southern Rockies to the central/southern Appalachians, and the Great Lakes to the Gulf. The 500-mb low should wobble erratically through the period while taking a net eastward path up the lower Ohio Valley region. Just outside the southern rim of the gyre's closed isohypses, a couple southern-stream shortwave troughs are apparent over the central and southeastern Gulf. In response, and along a surface boundary that long has moved offshore from the Atlantic Coast, a frontal-wave low was analyzed at 11Z over the western Straits of Florida, with a warm front extending eastward, south of the Keys and across the Bahamas. The low and front should remain just south of the Keys into early afternoon, as the low ripples eastward to east-northeastward toward the area between Bimini and Andros Island. A small complex of thunderstorms has been apparent for a few hours near the low, moving eastward to the south of the Dry Tortugas and Marquesas Keys. The expanding northern fringes of this activity north of the low -- and/or additional convection developing in the warm-advection regime farther downshear and north of the Straits boundary -- will pose some lightning potential across the Keys and southernmost parts of the peninsula through midday. Around 100-300 J/kg elevated MUCAPE, occasionally extending into icing layers suitable for lightning, should be present north of the boundary, before the leading shortwave trough passes. ..Edwards/Dean.. 12/28/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0637 AM CST Thu Dec 28 2023 Valid 281300Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... No severe thunderstorms are forecast across the contiguous U.S. through tonight. ...Synopsis/Discussion... A large, long-lived, nearly stacked, mid/upper-level low is evident in moisture-channel imagery over southern IL, with expansive cyclonic flow still apparent from the central/southern Rockies to the central/southern Appalachians, and the Great Lakes to the Gulf. The 500-mb low should wobble erratically through the period while taking a net eastward path up the lower Ohio Valley region. Just outside the southern rim of the gyre's closed isohypses, a couple southern-stream shortwave troughs are apparent over the central and southeastern Gulf. In response, and along a surface boundary that long has moved offshore from the Atlantic Coast, a frontal-wave low was analyzed at 11Z over the western Straits of Florida, with a warm front extending eastward, south of the Keys and across the Bahamas. The low and front should remain just south of the Keys into early afternoon, as the low ripples eastward to east-northeastward toward the area between Bimini and Andros Island. A small complex of thunderstorms has been apparent for a few hours near the low, moving eastward to the south of the Dry Tortugas and Marquesas Keys. The expanding northern fringes of this activity north of the low -- and/or additional convection developing in the warm-advection regime farther downshear and north of the Straits boundary -- will pose some lightning potential across the Keys and southernmost parts of the peninsula through midday. Around 100-300 J/kg elevated MUCAPE, occasionally extending into icing layers suitable for lightning, should be present north of the boundary, before the leading shortwave trough passes. ..Edwards/Dean.. 12/28/2023 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0313 AM CST Thu Dec 28 2023 Valid 311200Z - 051200Z ...DISCUSSION... A more progressive upper-level pattern will emerge during the Day 4-8 period. A series of upper shortwave troughs will move through southern-stream flow across the southern tier of the U.S. during this time. The first shortwave will move across the southern Plains to the Southeast on Days 4-5/Sun-Mon. In response, a surface low will develop over Texas, moving east over the northern Gulf or very near the LA/MS/AL coast through Monday. Modest low-level moisture may return as far north as the TX coast eastward. However, given the forecast track of the low being very near the Gulf coast, or over the northern Gulf waters, better quality moisture is expected to remain further south, limiting severe potential inland. A cold front will dive southeast across the Gulf on Day 5/Mon. Strong surface high pressure in the wake of this system will develop over the Plains to the southeastern U.S. for much of the rest of the period, resulting a dry and stable conditions. Another shortwave may move across the same general area (southern Plains to Southeast) late in the period around Day 7/Wed or Day 8/Thu. Another surface low could then track across the Gulf, though medium-range guidance varies considerably in this scenario. Nevertheless, most guidance suggests any low that develops will likely remain offshore, limiting severe potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0313 AM CST Thu Dec 28 2023 Valid 311200Z - 051200Z ...DISCUSSION... A more progressive upper-level pattern will emerge during the Day 4-8 period. A series of upper shortwave troughs will move through southern-stream flow across the southern tier of the U.S. during this time. The first shortwave will move across the southern Plains to the Southeast on Days 4-5/Sun-Mon. In response, a surface low will develop over Texas, moving east over the northern Gulf or very near the LA/MS/AL coast through Monday. Modest low-level moisture may return as far north as the TX coast eastward. However, given the forecast track of the low being very near the Gulf coast, or over the northern Gulf waters, better quality moisture is expected to remain further south, limiting severe potential inland. A cold front will dive southeast across the Gulf on Day 5/Mon. Strong surface high pressure in the wake of this system will develop over the Plains to the southeastern U.S. for much of the rest of the period, resulting a dry and stable conditions. Another shortwave may move across the same general area (southern Plains to Southeast) late in the period around Day 7/Wed or Day 8/Thu. Another surface low could then track across the Gulf, though medium-range guidance varies considerably in this scenario. Nevertheless, most guidance suggests any low that develops will likely remain offshore, limiting severe potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0313 AM CST Thu Dec 28 2023 Valid 311200Z - 051200Z ...DISCUSSION... A more progressive upper-level pattern will emerge during the Day 4-8 period. A series of upper shortwave troughs will move through southern-stream flow across the southern tier of the U.S. during this time. The first shortwave will move across the southern Plains to the Southeast on Days 4-5/Sun-Mon. In response, a surface low will develop over Texas, moving east over the northern Gulf or very near the LA/MS/AL coast through Monday. Modest low-level moisture may return as far north as the TX coast eastward. However, given the forecast track of the low being very near the Gulf coast, or over the northern Gulf waters, better quality moisture is expected to remain further south, limiting severe potential inland. A cold front will dive southeast across the Gulf on Day 5/Mon. Strong surface high pressure in the wake of this system will develop over the Plains to the southeastern U.S. for much of the rest of the period, resulting a dry and stable conditions. Another shortwave may move across the same general area (southern Plains to Southeast) late in the period around Day 7/Wed or Day 8/Thu. Another surface low could then track across the Gulf, though medium-range guidance varies considerably in this scenario. Nevertheless, most guidance suggests any low that develops will likely remain offshore, limiting severe potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0313 AM CST Thu Dec 28 2023 Valid 311200Z - 051200Z ...DISCUSSION... A more progressive upper-level pattern will emerge during the Day 4-8 period. A series of upper shortwave troughs will move through southern-stream flow across the southern tier of the U.S. during this time. The first shortwave will move across the southern Plains to the Southeast on Days 4-5/Sun-Mon. In response, a surface low will develop over Texas, moving east over the northern Gulf or very near the LA/MS/AL coast through Monday. Modest low-level moisture may return as far north as the TX coast eastward. However, given the forecast track of the low being very near the Gulf coast, or over the northern Gulf waters, better quality moisture is expected to remain further south, limiting severe potential inland. A cold front will dive southeast across the Gulf on Day 5/Mon. Strong surface high pressure in the wake of this system will develop over the Plains to the southeastern U.S. for much of the rest of the period, resulting a dry and stable conditions. Another shortwave may move across the same general area (southern Plains to Southeast) late in the period around Day 7/Wed or Day 8/Thu. Another surface low could then track across the Gulf, though medium-range guidance varies considerably in this scenario. Nevertheless, most guidance suggests any low that develops will likely remain offshore, limiting severe potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0313 AM CST Thu Dec 28 2023 Valid 311200Z - 051200Z ...DISCUSSION... A more progressive upper-level pattern will emerge during the Day 4-8 period. A series of upper shortwave troughs will move through southern-stream flow across the southern tier of the U.S. during this time. The first shortwave will move across the southern Plains to the Southeast on Days 4-5/Sun-Mon. In response, a surface low will develop over Texas, moving east over the northern Gulf or very near the LA/MS/AL coast through Monday. Modest low-level moisture may return as far north as the TX coast eastward. However, given the forecast track of the low being very near the Gulf coast, or over the northern Gulf waters, better quality moisture is expected to remain further south, limiting severe potential inland. A cold front will dive southeast across the Gulf on Day 5/Mon. Strong surface high pressure in the wake of this system will develop over the Plains to the southeastern U.S. for much of the rest of the period, resulting a dry and stable conditions. Another shortwave may move across the same general area (southern Plains to Southeast) late in the period around Day 7/Wed or Day 8/Thu. Another surface low could then track across the Gulf, though medium-range guidance varies considerably in this scenario. Nevertheless, most guidance suggests any low that develops will likely remain offshore, limiting severe potential. Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0146 AM CST Thu Dec 28 2023 Valid 301200Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are possible across portions of central California, mainly Saturday morning. Severe storms are not expected. ...Synopsis... An upper trough near the Pacific coast will continue to shift east through the period, becoming oriented over the Great Basin by Sunday morning. Showers and isolated thunderstorms may be ongoing Saturday morning near the central CA coast. This activity will likely continue into midday before thunderstorm chances diminish as the trough moves east. Dry and stable conditions across much of the rest of the CONUS will preclude thunderstorm activity elsewhere. ..Leitman.. 12/28/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0146 AM CST Thu Dec 28 2023 Valid 301200Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are possible across portions of central California, mainly Saturday morning. Severe storms are not expected. ...Synopsis... An upper trough near the Pacific coast will continue to shift east through the period, becoming oriented over the Great Basin by Sunday morning. Showers and isolated thunderstorms may be ongoing Saturday morning near the central CA coast. This activity will likely continue into midday before thunderstorm chances diminish as the trough moves east. Dry and stable conditions across much of the rest of the CONUS will preclude thunderstorm activity elsewhere. ..Leitman.. 12/28/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0146 AM CST Thu Dec 28 2023 Valid 301200Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are possible across portions of central California, mainly Saturday morning. Severe storms are not expected. ...Synopsis... An upper trough near the Pacific coast will continue to shift east through the period, becoming oriented over the Great Basin by Sunday morning. Showers and isolated thunderstorms may be ongoing Saturday morning near the central CA coast. This activity will likely continue into midday before thunderstorm chances diminish as the trough moves east. Dry and stable conditions across much of the rest of the CONUS will preclude thunderstorm activity elsewhere. ..Leitman.. 12/28/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0146 AM CST Thu Dec 28 2023 Valid 301200Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are possible across portions of central California, mainly Saturday morning. Severe storms are not expected. ...Synopsis... An upper trough near the Pacific coast will continue to shift east through the period, becoming oriented over the Great Basin by Sunday morning. Showers and isolated thunderstorms may be ongoing Saturday morning near the central CA coast. This activity will likely continue into midday before thunderstorm chances diminish as the trough moves east. Dry and stable conditions across much of the rest of the CONUS will preclude thunderstorm activity elsewhere. ..Leitman.. 12/28/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0146 AM CST Thu Dec 28 2023 Valid 301200Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are possible across portions of central California, mainly Saturday morning. Severe storms are not expected. ...Synopsis... An upper trough near the Pacific coast will continue to shift east through the period, becoming oriented over the Great Basin by Sunday morning. Showers and isolated thunderstorms may be ongoing Saturday morning near the central CA coast. This activity will likely continue into midday before thunderstorm chances diminish as the trough moves east. Dry and stable conditions across much of the rest of the CONUS will preclude thunderstorm activity elsewhere. ..Leitman.. 12/28/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1245 AM CST Thu Dec 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are possible along parts of the northern/central California coast on Friday. ...Synopsis... An amplified upper pattern will persist over the CONUS on Friday with a trough slowly migrating across the eastern U.S., while an upper ridge shifts east across the Intermountain West/Rockies. The main feature of interest with regards to thunderstorm potential will be an upper trough over the eastern Pacific, shifting east toward the Pacific coast late in the period. Deep-layer southwesterly flow ahead of the trough will bring increasing low- and mid-level moisture to coastal CA. Steepening midlevel lapse rates via cooling aloft will be sufficient for the development of weak instability Friday night/early Saturday morning. Isolated lightning flashes will be possible along the northern and central CA coast, mainly after 00z. Severe storms are not expected. Dry and stable conditions across most of the rest of the CONUS will preclude thunderstorm potential. ..Leitman.. 12/28/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1245 AM CST Thu Dec 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are possible along parts of the northern/central California coast on Friday. ...Synopsis... An amplified upper pattern will persist over the CONUS on Friday with a trough slowly migrating across the eastern U.S., while an upper ridge shifts east across the Intermountain West/Rockies. The main feature of interest with regards to thunderstorm potential will be an upper trough over the eastern Pacific, shifting east toward the Pacific coast late in the period. Deep-layer southwesterly flow ahead of the trough will bring increasing low- and mid-level moisture to coastal CA. Steepening midlevel lapse rates via cooling aloft will be sufficient for the development of weak instability Friday night/early Saturday morning. Isolated lightning flashes will be possible along the northern and central CA coast, mainly after 00z. Severe storms are not expected. Dry and stable conditions across most of the rest of the CONUS will preclude thunderstorm potential. ..Leitman.. 12/28/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1245 AM CST Thu Dec 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are possible along parts of the northern/central California coast on Friday. ...Synopsis... An amplified upper pattern will persist over the CONUS on Friday with a trough slowly migrating across the eastern U.S., while an upper ridge shifts east across the Intermountain West/Rockies. The main feature of interest with regards to thunderstorm potential will be an upper trough over the eastern Pacific, shifting east toward the Pacific coast late in the period. Deep-layer southwesterly flow ahead of the trough will bring increasing low- and mid-level moisture to coastal CA. Steepening midlevel lapse rates via cooling aloft will be sufficient for the development of weak instability Friday night/early Saturday morning. Isolated lightning flashes will be possible along the northern and central CA coast, mainly after 00z. Severe storms are not expected. Dry and stable conditions across most of the rest of the CONUS will preclude thunderstorm potential. ..Leitman.. 12/28/2023 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1245 AM CST Thu Dec 28 2023 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are possible along parts of the northern/central California coast on Friday. ...Synopsis... An amplified upper pattern will persist over the CONUS on Friday with a trough slowly migrating across the eastern U.S., while an upper ridge shifts east across the Intermountain West/Rockies. The main feature of interest with regards to thunderstorm potential will be an upper trough over the eastern Pacific, shifting east toward the Pacific coast late in the period. Deep-layer southwesterly flow ahead of the trough will bring increasing low- and mid-level moisture to coastal CA. Steepening midlevel lapse rates via cooling aloft will be sufficient for the development of weak instability Friday night/early Saturday morning. Isolated lightning flashes will be possible along the northern and central CA coast, mainly after 00z. Severe storms are not expected. Dry and stable conditions across most of the rest of the CONUS will preclude thunderstorm potential. ..Leitman.. 12/28/2023 Read more