Severe Storms

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0200 AM CST Sat Dec 14 2024 Valid 141200Z - 151200Z ...NO CRITICAL AREAS... ...Synopsis... A progressive mid-level trough moving over the Southern Plains will rapidly move eastward as shortwave ridging develops over the Rockies and High Plains in its wake. A second mid-level trough farther west will begin to approach later this evening and overnight as increasingly strong westerly flow overspreads the Plains again. The ridging will initially favor weak surface winds and relatively mild temperatures through much of the day before the approaching trough aids in developing a lee cyclone over the central and northern High Plains. The deepening low and strong westerly winds aloft may support downslope flow over parts of the Rockies and High Plains with gusts of 20-30 mph. However, the late arrival of the trough, poorly timed with the diurnal cycle, will favor relatively poor overlap with low RH values. This should limit fire-weather concerns across the CONUS. ..Lyons.. 12/14/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0200 AM CST Sat Dec 14 2024 Valid 141200Z - 151200Z ...NO CRITICAL AREAS... ...Synopsis... A progressive mid-level trough moving over the Southern Plains will rapidly move eastward as shortwave ridging develops over the Rockies and High Plains in its wake. A second mid-level trough farther west will begin to approach later this evening and overnight as increasingly strong westerly flow overspreads the Plains again. The ridging will initially favor weak surface winds and relatively mild temperatures through much of the day before the approaching trough aids in developing a lee cyclone over the central and northern High Plains. The deepening low and strong westerly winds aloft may support downslope flow over parts of the Rockies and High Plains with gusts of 20-30 mph. However, the late arrival of the trough, poorly timed with the diurnal cycle, will favor relatively poor overlap with low RH values. This should limit fire-weather concerns across the CONUS. ..Lyons.. 12/14/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0149 AM CST Sat Dec 14 2024 Valid 161200Z - 171200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is expected to be low on Monday. ...South-Central States... An upper trough over the Plains will shift east across the Midwest and into the Northeast on Monday. The bulk of stronger deep-layer flow and large-scale ascent will be focused across the Mid-MS and OH Valley region. At the surface, a cold front will develop east across the Midwest, while the southwest extent of the boundary drops more south/southeast across parts of the southern Plains and the Lower MS Valley. The front should extend from northern MS into central TX by early Tuesday. Southerly low-level flow ahead of the front will maintain upper 50s to mid 60s dewpoints over the eastern half of TX into the Mid-South and Lower MS Valley. While this will aid in modest destabilization across portions of southern/central TX toward the ArkLaTex vicinity, vertical shear is expected to be modest (less than 25 kt effective shear magnitudes) and large-scale ascent will remain displaced well to the north. As a result, severe-thunderstorm potential appears low. ..Leitman.. 12/14/2024 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0149 AM CST Sat Dec 14 2024 Valid 161200Z - 171200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is expected to be low on Monday. ...South-Central States... An upper trough over the Plains will shift east across the Midwest and into the Northeast on Monday. The bulk of stronger deep-layer flow and large-scale ascent will be focused across the Mid-MS and OH Valley region. At the surface, a cold front will develop east across the Midwest, while the southwest extent of the boundary drops more south/southeast across parts of the southern Plains and the Lower MS Valley. The front should extend from northern MS into central TX by early Tuesday. Southerly low-level flow ahead of the front will maintain upper 50s to mid 60s dewpoints over the eastern half of TX into the Mid-South and Lower MS Valley. While this will aid in modest destabilization across portions of southern/central TX toward the ArkLaTex vicinity, vertical shear is expected to be modest (less than 25 kt effective shear magnitudes) and large-scale ascent will remain displaced well to the north. As a result, severe-thunderstorm potential appears low. ..Leitman.. 12/14/2024 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0149 AM CST Sat Dec 14 2024 Valid 161200Z - 171200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is expected to be low on Monday. ...South-Central States... An upper trough over the Plains will shift east across the Midwest and into the Northeast on Monday. The bulk of stronger deep-layer flow and large-scale ascent will be focused across the Mid-MS and OH Valley region. At the surface, a cold front will develop east across the Midwest, while the southwest extent of the boundary drops more south/southeast across parts of the southern Plains and the Lower MS Valley. The front should extend from northern MS into central TX by early Tuesday. Southerly low-level flow ahead of the front will maintain upper 50s to mid 60s dewpoints over the eastern half of TX into the Mid-South and Lower MS Valley. While this will aid in modest destabilization across portions of southern/central TX toward the ArkLaTex vicinity, vertical shear is expected to be modest (less than 25 kt effective shear magnitudes) and large-scale ascent will remain displaced well to the north. As a result, severe-thunderstorm potential appears low. ..Leitman.. 12/14/2024 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0149 AM CST Sat Dec 14 2024 Valid 161200Z - 171200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is expected to be low on Monday. ...South-Central States... An upper trough over the Plains will shift east across the Midwest and into the Northeast on Monday. The bulk of stronger deep-layer flow and large-scale ascent will be focused across the Mid-MS and OH Valley region. At the surface, a cold front will develop east across the Midwest, while the southwest extent of the boundary drops more south/southeast across parts of the southern Plains and the Lower MS Valley. The front should extend from northern MS into central TX by early Tuesday. Southerly low-level flow ahead of the front will maintain upper 50s to mid 60s dewpoints over the eastern half of TX into the Mid-South and Lower MS Valley. While this will aid in modest destabilization across portions of southern/central TX toward the ArkLaTex vicinity, vertical shear is expected to be modest (less than 25 kt effective shear magnitudes) and large-scale ascent will remain displaced well to the north. As a result, severe-thunderstorm potential appears low. ..Leitman.. 12/14/2024 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0149 AM CST Sat Dec 14 2024 Valid 161200Z - 171200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is expected to be low on Monday. ...South-Central States... An upper trough over the Plains will shift east across the Midwest and into the Northeast on Monday. The bulk of stronger deep-layer flow and large-scale ascent will be focused across the Mid-MS and OH Valley region. At the surface, a cold front will develop east across the Midwest, while the southwest extent of the boundary drops more south/southeast across parts of the southern Plains and the Lower MS Valley. The front should extend from northern MS into central TX by early Tuesday. Southerly low-level flow ahead of the front will maintain upper 50s to mid 60s dewpoints over the eastern half of TX into the Mid-South and Lower MS Valley. While this will aid in modest destabilization across portions of southern/central TX toward the ArkLaTex vicinity, vertical shear is expected to be modest (less than 25 kt effective shear magnitudes) and large-scale ascent will remain displaced well to the north. As a result, severe-thunderstorm potential appears low. ..Leitman.. 12/14/2024 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1149 PM CST Fri Dec 13 2024 Valid 151200Z - 161200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is expected to remain limited on Sunday. ...Synopsis... An upper trough will shift east into the Plains Sunday night into early Monday. As a result, enhanced deep-layer southwesterly mid/upper flow will envelop the central/southern Plains toward the Mid/Upper MS Valley. At the surface, a deepening low will track east along the international border in the vicinity of the northern Plains and Upper Midwest. A trailing cold front is forecast to move southeast across much of the northern/central Plains and Upper Midwest, becoming positioned from central MO southwestward into northwest TX by 12z Monday. Southerly low-level flow ahead of the aforementioned front will allow upper 50s to mid 60s dewpoints to spread northward across much of TX into eastern OK, LA, AR and southern MO. Shortwave upper ridging for much of the period prior to 03z will likely preclude thunderstorm activity within the warm conveyor. However, stronger height falls associated with the ejecting trough will overspread the southern Plains (though stronger large-scale ascent will remain focused further north). Isolated to scattered thunderstorms are likely to develop near the southeastward-advancing cold front in the 06-12z time frame. Favorable, vertically veering wind profiles suggest some thunderstorm organization will be possible. However, convection is expected to mostly remain elevated in nature given cool surface temperatures overnight, resulting in little surface-based instability and poor low-level lapse rates. Furthermore, deep-layer flow will remain parallel to the front, resulting in convection tracking to the cool side of the boundary. Given cool temperatures aloft and midlevel lapse rates approaching 7 C/km in a moderately sheared environment, some small hail could accompany the strongest updrafts across eastern OK into parts of AR and southern MO. However, overall severe potential appears low/too conditional to include probabilities at this time given stronger large-scale ascent focused further north of better low-level moisture, and expectation for limited surface-based instability. ..Leitman.. 12/14/2024 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1149 PM CST Fri Dec 13 2024 Valid 151200Z - 161200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is expected to remain limited on Sunday. ...Synopsis... An upper trough will shift east into the Plains Sunday night into early Monday. As a result, enhanced deep-layer southwesterly mid/upper flow will envelop the central/southern Plains toward the Mid/Upper MS Valley. At the surface, a deepening low will track east along the international border in the vicinity of the northern Plains and Upper Midwest. A trailing cold front is forecast to move southeast across much of the northern/central Plains and Upper Midwest, becoming positioned from central MO southwestward into northwest TX by 12z Monday. Southerly low-level flow ahead of the aforementioned front will allow upper 50s to mid 60s dewpoints to spread northward across much of TX into eastern OK, LA, AR and southern MO. Shortwave upper ridging for much of the period prior to 03z will likely preclude thunderstorm activity within the warm conveyor. However, stronger height falls associated with the ejecting trough will overspread the southern Plains (though stronger large-scale ascent will remain focused further north). Isolated to scattered thunderstorms are likely to develop near the southeastward-advancing cold front in the 06-12z time frame. Favorable, vertically veering wind profiles suggest some thunderstorm organization will be possible. However, convection is expected to mostly remain elevated in nature given cool surface temperatures overnight, resulting in little surface-based instability and poor low-level lapse rates. Furthermore, deep-layer flow will remain parallel to the front, resulting in convection tracking to the cool side of the boundary. Given cool temperatures aloft and midlevel lapse rates approaching 7 C/km in a moderately sheared environment, some small hail could accompany the strongest updrafts across eastern OK into parts of AR and southern MO. However, overall severe potential appears low/too conditional to include probabilities at this time given stronger large-scale ascent focused further north of better low-level moisture, and expectation for limited surface-based instability. ..Leitman.. 12/14/2024 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1149 PM CST Fri Dec 13 2024 Valid 151200Z - 161200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is expected to remain limited on Sunday. ...Synopsis... An upper trough will shift east into the Plains Sunday night into early Monday. As a result, enhanced deep-layer southwesterly mid/upper flow will envelop the central/southern Plains toward the Mid/Upper MS Valley. At the surface, a deepening low will track east along the international border in the vicinity of the northern Plains and Upper Midwest. A trailing cold front is forecast to move southeast across much of the northern/central Plains and Upper Midwest, becoming positioned from central MO southwestward into northwest TX by 12z Monday. Southerly low-level flow ahead of the aforementioned front will allow upper 50s to mid 60s dewpoints to spread northward across much of TX into eastern OK, LA, AR and southern MO. Shortwave upper ridging for much of the period prior to 03z will likely preclude thunderstorm activity within the warm conveyor. However, stronger height falls associated with the ejecting trough will overspread the southern Plains (though stronger large-scale ascent will remain focused further north). Isolated to scattered thunderstorms are likely to develop near the southeastward-advancing cold front in the 06-12z time frame. Favorable, vertically veering wind profiles suggest some thunderstorm organization will be possible. However, convection is expected to mostly remain elevated in nature given cool surface temperatures overnight, resulting in little surface-based instability and poor low-level lapse rates. Furthermore, deep-layer flow will remain parallel to the front, resulting in convection tracking to the cool side of the boundary. Given cool temperatures aloft and midlevel lapse rates approaching 7 C/km in a moderately sheared environment, some small hail could accompany the strongest updrafts across eastern OK into parts of AR and southern MO. However, overall severe potential appears low/too conditional to include probabilities at this time given stronger large-scale ascent focused further north of better low-level moisture, and expectation for limited surface-based instability. ..Leitman.. 12/14/2024 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1149 PM CST Fri Dec 13 2024 Valid 151200Z - 161200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is expected to remain limited on Sunday. ...Synopsis... An upper trough will shift east into the Plains Sunday night into early Monday. As a result, enhanced deep-layer southwesterly mid/upper flow will envelop the central/southern Plains toward the Mid/Upper MS Valley. At the surface, a deepening low will track east along the international border in the vicinity of the northern Plains and Upper Midwest. A trailing cold front is forecast to move southeast across much of the northern/central Plains and Upper Midwest, becoming positioned from central MO southwestward into northwest TX by 12z Monday. Southerly low-level flow ahead of the aforementioned front will allow upper 50s to mid 60s dewpoints to spread northward across much of TX into eastern OK, LA, AR and southern MO. Shortwave upper ridging for much of the period prior to 03z will likely preclude thunderstorm activity within the warm conveyor. However, stronger height falls associated with the ejecting trough will overspread the southern Plains (though stronger large-scale ascent will remain focused further north). Isolated to scattered thunderstorms are likely to develop near the southeastward-advancing cold front in the 06-12z time frame. Favorable, vertically veering wind profiles suggest some thunderstorm organization will be possible. However, convection is expected to mostly remain elevated in nature given cool surface temperatures overnight, resulting in little surface-based instability and poor low-level lapse rates. Furthermore, deep-layer flow will remain parallel to the front, resulting in convection tracking to the cool side of the boundary. Given cool temperatures aloft and midlevel lapse rates approaching 7 C/km in a moderately sheared environment, some small hail could accompany the strongest updrafts across eastern OK into parts of AR and southern MO. However, overall severe potential appears low/too conditional to include probabilities at this time given stronger large-scale ascent focused further north of better low-level moisture, and expectation for limited surface-based instability. ..Leitman.. 12/14/2024 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1149 PM CST Fri Dec 13 2024 Valid 151200Z - 161200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is expected to remain limited on Sunday. ...Synopsis... An upper trough will shift east into the Plains Sunday night into early Monday. As a result, enhanced deep-layer southwesterly mid/upper flow will envelop the central/southern Plains toward the Mid/Upper MS Valley. At the surface, a deepening low will track east along the international border in the vicinity of the northern Plains and Upper Midwest. A trailing cold front is forecast to move southeast across much of the northern/central Plains and Upper Midwest, becoming positioned from central MO southwestward into northwest TX by 12z Monday. Southerly low-level flow ahead of the aforementioned front will allow upper 50s to mid 60s dewpoints to spread northward across much of TX into eastern OK, LA, AR and southern MO. Shortwave upper ridging for much of the period prior to 03z will likely preclude thunderstorm activity within the warm conveyor. However, stronger height falls associated with the ejecting trough will overspread the southern Plains (though stronger large-scale ascent will remain focused further north). Isolated to scattered thunderstorms are likely to develop near the southeastward-advancing cold front in the 06-12z time frame. Favorable, vertically veering wind profiles suggest some thunderstorm organization will be possible. However, convection is expected to mostly remain elevated in nature given cool surface temperatures overnight, resulting in little surface-based instability and poor low-level lapse rates. Furthermore, deep-layer flow will remain parallel to the front, resulting in convection tracking to the cool side of the boundary. Given cool temperatures aloft and midlevel lapse rates approaching 7 C/km in a moderately sheared environment, some small hail could accompany the strongest updrafts across eastern OK into parts of AR and southern MO. However, overall severe potential appears low/too conditional to include probabilities at this time given stronger large-scale ascent focused further north of better low-level moisture, and expectation for limited surface-based instability. ..Leitman.. 12/14/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1147 PM CST Fri Dec 13 2024 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN A PART OF THE BAY AREA TO CENTRAL COAST OF CA... ...SUMMARY... Strong to isolated severe gusts may accompany low-topped thunderstorms this morning across parts of the Bay Area and Central Coast of California. ...Bay Area to Central Coast of CA... A vigorous shortwave impulse, embedded within the basal portion of a northeast Pacific upper trough, will rapidly approach the Bay Area this morning. Very strong forcing for ascent will accompany this wave, supporting low-topped thunderstorms, as evidenced by ongoing CG lightning around 400-500 miles off the coast. While the time of day (12-16Z) will be unfavorable, a narrow corridor of meager surface-based instability should approach the coast. This should overlap the western portion of a 55-65 kt low-level jet. Despite the low-topped nature of thunderstorms, linear clusters within the low-level warm conveyor and near the attendant surface low will be capable of producing strong to isolated severe gusts. This threat should diminish by late morning as the shortwave trough rapidly progresses inland with negligible surface-based instability. ...East-Southeast TX... As a compact shortwave trough progresses from the central Great Plains eastward into the Midwest, its attendant minor surface wave will undergo cyclolysis by early Sunday. The accompanying cold front trailing to its south-southwest should stall and weaken in parts of northeast to central TX. The low-level warm conveyor ahead of the front will foster elevated thunderstorms, mainly this morning that linger into the afternoon. Some surface-based development is possible along the trailing portion into east-southeast TX should adequate boundary-layer heating of low to mid 60s surface dew points occur. But with weakening large-scale ascent/deep-layer shear and muted mid-level lapse rates, severe potential appears negligible. ..Grams/Lyons.. 12/14/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1147 PM CST Fri Dec 13 2024 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN A PART OF THE BAY AREA TO CENTRAL COAST OF CA... ...SUMMARY... Strong to isolated severe gusts may accompany low-topped thunderstorms this morning across parts of the Bay Area and Central Coast of California. ...Bay Area to Central Coast of CA... A vigorous shortwave impulse, embedded within the basal portion of a northeast Pacific upper trough, will rapidly approach the Bay Area this morning. Very strong forcing for ascent will accompany this wave, supporting low-topped thunderstorms, as evidenced by ongoing CG lightning around 400-500 miles off the coast. While the time of day (12-16Z) will be unfavorable, a narrow corridor of meager surface-based instability should approach the coast. This should overlap the western portion of a 55-65 kt low-level jet. Despite the low-topped nature of thunderstorms, linear clusters within the low-level warm conveyor and near the attendant surface low will be capable of producing strong to isolated severe gusts. This threat should diminish by late morning as the shortwave trough rapidly progresses inland with negligible surface-based instability. ...East-Southeast TX... As a compact shortwave trough progresses from the central Great Plains eastward into the Midwest, its attendant minor surface wave will undergo cyclolysis by early Sunday. The accompanying cold front trailing to its south-southwest should stall and weaken in parts of northeast to central TX. The low-level warm conveyor ahead of the front will foster elevated thunderstorms, mainly this morning that linger into the afternoon. Some surface-based development is possible along the trailing portion into east-southeast TX should adequate boundary-layer heating of low to mid 60s surface dew points occur. But with weakening large-scale ascent/deep-layer shear and muted mid-level lapse rates, severe potential appears negligible. ..Grams/Lyons.. 12/14/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1147 PM CST Fri Dec 13 2024 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN A PART OF THE BAY AREA TO CENTRAL COAST OF CA... ...SUMMARY... Strong to isolated severe gusts may accompany low-topped thunderstorms this morning across parts of the Bay Area and Central Coast of California. ...Bay Area to Central Coast of CA... A vigorous shortwave impulse, embedded within the basal portion of a northeast Pacific upper trough, will rapidly approach the Bay Area this morning. Very strong forcing for ascent will accompany this wave, supporting low-topped thunderstorms, as evidenced by ongoing CG lightning around 400-500 miles off the coast. While the time of day (12-16Z) will be unfavorable, a narrow corridor of meager surface-based instability should approach the coast. This should overlap the western portion of a 55-65 kt low-level jet. Despite the low-topped nature of thunderstorms, linear clusters within the low-level warm conveyor and near the attendant surface low will be capable of producing strong to isolated severe gusts. This threat should diminish by late morning as the shortwave trough rapidly progresses inland with negligible surface-based instability. ...East-Southeast TX... As a compact shortwave trough progresses from the central Great Plains eastward into the Midwest, its attendant minor surface wave will undergo cyclolysis by early Sunday. The accompanying cold front trailing to its south-southwest should stall and weaken in parts of northeast to central TX. The low-level warm conveyor ahead of the front will foster elevated thunderstorms, mainly this morning that linger into the afternoon. Some surface-based development is possible along the trailing portion into east-southeast TX should adequate boundary-layer heating of low to mid 60s surface dew points occur. But with weakening large-scale ascent/deep-layer shear and muted mid-level lapse rates, severe potential appears negligible. ..Grams/Lyons.. 12/14/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1147 PM CST Fri Dec 13 2024 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN A PART OF THE BAY AREA TO CENTRAL COAST OF CA... ...SUMMARY... Strong to isolated severe gusts may accompany low-topped thunderstorms this morning across parts of the Bay Area and Central Coast of California. ...Bay Area to Central Coast of CA... A vigorous shortwave impulse, embedded within the basal portion of a northeast Pacific upper trough, will rapidly approach the Bay Area this morning. Very strong forcing for ascent will accompany this wave, supporting low-topped thunderstorms, as evidenced by ongoing CG lightning around 400-500 miles off the coast. While the time of day (12-16Z) will be unfavorable, a narrow corridor of meager surface-based instability should approach the coast. This should overlap the western portion of a 55-65 kt low-level jet. Despite the low-topped nature of thunderstorms, linear clusters within the low-level warm conveyor and near the attendant surface low will be capable of producing strong to isolated severe gusts. This threat should diminish by late morning as the shortwave trough rapidly progresses inland with negligible surface-based instability. ...East-Southeast TX... As a compact shortwave trough progresses from the central Great Plains eastward into the Midwest, its attendant minor surface wave will undergo cyclolysis by early Sunday. The accompanying cold front trailing to its south-southwest should stall and weaken in parts of northeast to central TX. The low-level warm conveyor ahead of the front will foster elevated thunderstorms, mainly this morning that linger into the afternoon. Some surface-based development is possible along the trailing portion into east-southeast TX should adequate boundary-layer heating of low to mid 60s surface dew points occur. But with weakening large-scale ascent/deep-layer shear and muted mid-level lapse rates, severe potential appears negligible. ..Grams/Lyons.. 12/14/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1147 PM CST Fri Dec 13 2024 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN A PART OF THE BAY AREA TO CENTRAL COAST OF CA... ...SUMMARY... Strong to isolated severe gusts may accompany low-topped thunderstorms this morning across parts of the Bay Area and Central Coast of California. ...Bay Area to Central Coast of CA... A vigorous shortwave impulse, embedded within the basal portion of a northeast Pacific upper trough, will rapidly approach the Bay Area this morning. Very strong forcing for ascent will accompany this wave, supporting low-topped thunderstorms, as evidenced by ongoing CG lightning around 400-500 miles off the coast. While the time of day (12-16Z) will be unfavorable, a narrow corridor of meager surface-based instability should approach the coast. This should overlap the western portion of a 55-65 kt low-level jet. Despite the low-topped nature of thunderstorms, linear clusters within the low-level warm conveyor and near the attendant surface low will be capable of producing strong to isolated severe gusts. This threat should diminish by late morning as the shortwave trough rapidly progresses inland with negligible surface-based instability. ...East-Southeast TX... As a compact shortwave trough progresses from the central Great Plains eastward into the Midwest, its attendant minor surface wave will undergo cyclolysis by early Sunday. The accompanying cold front trailing to its south-southwest should stall and weaken in parts of northeast to central TX. The low-level warm conveyor ahead of the front will foster elevated thunderstorms, mainly this morning that linger into the afternoon. Some surface-based development is possible along the trailing portion into east-southeast TX should adequate boundary-layer heating of low to mid 60s surface dew points occur. But with weakening large-scale ascent/deep-layer shear and muted mid-level lapse rates, severe potential appears negligible. ..Grams/Lyons.. 12/14/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0654 PM CST Fri Dec 13 2024 Valid 140100Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected tonight. ...Southern/Central Plains into the Ozarks/ArkLaTex... A compact shortwave trough will gradually shift east across the central Great Plains tonight. While its associated surface reflection in the Raton Mesa vicinity will remain weak as it similarly tracks near the KS/OK border, low-level mass response will strengthen this evening. This will yield an abrupt increase in elevated convection overnight. Steep mid-level lapse rates will largely be confined from the Red River northward, where MUCAPE will remain weak along the periphery of the modified moisture return. 60s surface dew points will remain confined across parts of south into central TX, where mid-level lapse rates will be more muted. Still, with a relatively broad swath of greater than 50-kt 500-mb winds from north TX into eastern KS and the Ozarks, small hail may occur in the deepest updrafts. ...Northern CA... An upper trough will approach the West Coast late tonight into early morning. Associated low-level warm/moist advection will occur ahead of a weak surface front, with a broad area of precipitation. Gradual cooling of mid-level temperatures will occur as the upper trough approaches, which may support meager MUCAPE across parts of northern CA during the 09-12Z period. Sporadic lightning flashes may occur with low-topped convection along/near the front, with overall thunderstorm probabilities around 10 percent. ..Grams.. 12/14/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0654 PM CST Fri Dec 13 2024 Valid 140100Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected tonight. ...Southern/Central Plains into the Ozarks/ArkLaTex... A compact shortwave trough will gradually shift east across the central Great Plains tonight. While its associated surface reflection in the Raton Mesa vicinity will remain weak as it similarly tracks near the KS/OK border, low-level mass response will strengthen this evening. This will yield an abrupt increase in elevated convection overnight. Steep mid-level lapse rates will largely be confined from the Red River northward, where MUCAPE will remain weak along the periphery of the modified moisture return. 60s surface dew points will remain confined across parts of south into central TX, where mid-level lapse rates will be more muted. Still, with a relatively broad swath of greater than 50-kt 500-mb winds from north TX into eastern KS and the Ozarks, small hail may occur in the deepest updrafts. ...Northern CA... An upper trough will approach the West Coast late tonight into early morning. Associated low-level warm/moist advection will occur ahead of a weak surface front, with a broad area of precipitation. Gradual cooling of mid-level temperatures will occur as the upper trough approaches, which may support meager MUCAPE across parts of northern CA during the 09-12Z period. Sporadic lightning flashes may occur with low-topped convection along/near the front, with overall thunderstorm probabilities around 10 percent. ..Grams.. 12/14/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0654 PM CST Fri Dec 13 2024 Valid 140100Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected tonight. ...Southern/Central Plains into the Ozarks/ArkLaTex... A compact shortwave trough will gradually shift east across the central Great Plains tonight. While its associated surface reflection in the Raton Mesa vicinity will remain weak as it similarly tracks near the KS/OK border, low-level mass response will strengthen this evening. This will yield an abrupt increase in elevated convection overnight. Steep mid-level lapse rates will largely be confined from the Red River northward, where MUCAPE will remain weak along the periphery of the modified moisture return. 60s surface dew points will remain confined across parts of south into central TX, where mid-level lapse rates will be more muted. Still, with a relatively broad swath of greater than 50-kt 500-mb winds from north TX into eastern KS and the Ozarks, small hail may occur in the deepest updrafts. ...Northern CA... An upper trough will approach the West Coast late tonight into early morning. Associated low-level warm/moist advection will occur ahead of a weak surface front, with a broad area of precipitation. Gradual cooling of mid-level temperatures will occur as the upper trough approaches, which may support meager MUCAPE across parts of northern CA during the 09-12Z period. Sporadic lightning flashes may occur with low-topped convection along/near the front, with overall thunderstorm probabilities around 10 percent. ..Grams.. 12/14/2024 Read more