Severe Storms

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

No Mesoscale Discussions are in effect as of Fri Dec 13 22:27:01 UTC 2024.

No watches are valid as of Fri Dec 13 22:27:01 UTC 2024.

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0314 PM CST Fri Dec 13 2024 Valid 151200Z - 211200Z The upper-level pattern is expected to remain progressive through early next week. Some flow amplification appears probable by Tuesday into Wednesday. Thereafter, model guidance suggests a broad trough in the East with a amplified ridge in the West. At the surface, cold air will move into most areas east of the Divide with each successive trough moving across the CONUS. Areas of the Southwest and southern High Plains will likely remain dry during the extended period. Despite relatively dry fuels in these areas, winds are expected to remain modest. Ensemble guidance consequently shows low probabilities for critical fire weather. As the upper-level ridge amplifies in the West, surface high pressure is expected to build into the Great Basin, peaking on Wednesday morning. This pattern would favor offshore winds across the typically wind-prone areas of southern California. Given the large scale features involved, in addition to a consistent signal in ensemble guidance, 40% probabilities were added for Tuesday night into Wednesday morning when the offshore pressure gradient is expected to be maximized. At this point in time, upper-level wind support is expected to be weak. ..Wendt.. 12/13/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0314 PM CST Fri Dec 13 2024 Valid 151200Z - 211200Z The upper-level pattern is expected to remain progressive through early next week. Some flow amplification appears probable by Tuesday into Wednesday. Thereafter, model guidance suggests a broad trough in the East with a amplified ridge in the West. At the surface, cold air will move into most areas east of the Divide with each successive trough moving across the CONUS. Areas of the Southwest and southern High Plains will likely remain dry during the extended period. Despite relatively dry fuels in these areas, winds are expected to remain modest. Ensemble guidance consequently shows low probabilities for critical fire weather. As the upper-level ridge amplifies in the West, surface high pressure is expected to build into the Great Basin, peaking on Wednesday morning. This pattern would favor offshore winds across the typically wind-prone areas of southern California. Given the large scale features involved, in addition to a consistent signal in ensemble guidance, 40% probabilities were added for Tuesday night into Wednesday morning when the offshore pressure gradient is expected to be maximized. At this point in time, upper-level wind support is expected to be weak. ..Wendt.. 12/13/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0314 PM CST Fri Dec 13 2024 Valid 151200Z - 211200Z The upper-level pattern is expected to remain progressive through early next week. Some flow amplification appears probable by Tuesday into Wednesday. Thereafter, model guidance suggests a broad trough in the East with a amplified ridge in the West. At the surface, cold air will move into most areas east of the Divide with each successive trough moving across the CONUS. Areas of the Southwest and southern High Plains will likely remain dry during the extended period. Despite relatively dry fuels in these areas, winds are expected to remain modest. Ensemble guidance consequently shows low probabilities for critical fire weather. As the upper-level ridge amplifies in the West, surface high pressure is expected to build into the Great Basin, peaking on Wednesday morning. This pattern would favor offshore winds across the typically wind-prone areas of southern California. Given the large scale features involved, in addition to a consistent signal in ensemble guidance, 40% probabilities were added for Tuesday night into Wednesday morning when the offshore pressure gradient is expected to be maximized. At this point in time, upper-level wind support is expected to be weak. ..Wendt.. 12/13/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0314 PM CST Fri Dec 13 2024 Valid 151200Z - 211200Z The upper-level pattern is expected to remain progressive through early next week. Some flow amplification appears probable by Tuesday into Wednesday. Thereafter, model guidance suggests a broad trough in the East with a amplified ridge in the West. At the surface, cold air will move into most areas east of the Divide with each successive trough moving across the CONUS. Areas of the Southwest and southern High Plains will likely remain dry during the extended period. Despite relatively dry fuels in these areas, winds are expected to remain modest. Ensemble guidance consequently shows low probabilities for critical fire weather. As the upper-level ridge amplifies in the West, surface high pressure is expected to build into the Great Basin, peaking on Wednesday morning. This pattern would favor offshore winds across the typically wind-prone areas of southern California. Given the large scale features involved, in addition to a consistent signal in ensemble guidance, 40% probabilities were added for Tuesday night into Wednesday morning when the offshore pressure gradient is expected to be maximized. At this point in time, upper-level wind support is expected to be weak. ..Wendt.. 12/13/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0314 PM CST Fri Dec 13 2024 Valid 151200Z - 211200Z The upper-level pattern is expected to remain progressive through early next week. Some flow amplification appears probable by Tuesday into Wednesday. Thereafter, model guidance suggests a broad trough in the East with a amplified ridge in the West. At the surface, cold air will move into most areas east of the Divide with each successive trough moving across the CONUS. Areas of the Southwest and southern High Plains will likely remain dry during the extended period. Despite relatively dry fuels in these areas, winds are expected to remain modest. Ensemble guidance consequently shows low probabilities for critical fire weather. As the upper-level ridge amplifies in the West, surface high pressure is expected to build into the Great Basin, peaking on Wednesday morning. This pattern would favor offshore winds across the typically wind-prone areas of southern California. Given the large scale features involved, in addition to a consistent signal in ensemble guidance, 40% probabilities were added for Tuesday night into Wednesday morning when the offshore pressure gradient is expected to be maximized. At this point in time, upper-level wind support is expected to be weak. ..Wendt.. 12/13/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0314 PM CST Fri Dec 13 2024 Valid 151200Z - 211200Z The upper-level pattern is expected to remain progressive through early next week. Some flow amplification appears probable by Tuesday into Wednesday. Thereafter, model guidance suggests a broad trough in the East with a amplified ridge in the West. At the surface, cold air will move into most areas east of the Divide with each successive trough moving across the CONUS. Areas of the Southwest and southern High Plains will likely remain dry during the extended period. Despite relatively dry fuels in these areas, winds are expected to remain modest. Ensemble guidance consequently shows low probabilities for critical fire weather. As the upper-level ridge amplifies in the West, surface high pressure is expected to build into the Great Basin, peaking on Wednesday morning. This pattern would favor offshore winds across the typically wind-prone areas of southern California. Given the large scale features involved, in addition to a consistent signal in ensemble guidance, 40% probabilities were added for Tuesday night into Wednesday morning when the offshore pressure gradient is expected to be maximized. At this point in time, upper-level wind support is expected to be weak. ..Wendt.. 12/13/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0314 PM CST Fri Dec 13 2024 Valid 151200Z - 211200Z The upper-level pattern is expected to remain progressive through early next week. Some flow amplification appears probable by Tuesday into Wednesday. Thereafter, model guidance suggests a broad trough in the East with a amplified ridge in the West. At the surface, cold air will move into most areas east of the Divide with each successive trough moving across the CONUS. Areas of the Southwest and southern High Plains will likely remain dry during the extended period. Despite relatively dry fuels in these areas, winds are expected to remain modest. Ensemble guidance consequently shows low probabilities for critical fire weather. As the upper-level ridge amplifies in the West, surface high pressure is expected to build into the Great Basin, peaking on Wednesday morning. This pattern would favor offshore winds across the typically wind-prone areas of southern California. Given the large scale features involved, in addition to a consistent signal in ensemble guidance, 40% probabilities were added for Tuesday night into Wednesday morning when the offshore pressure gradient is expected to be maximized. At this point in time, upper-level wind support is expected to be weak. ..Wendt.. 12/13/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0142 PM CST Fri Dec 13 2024 Valid 132000Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely through tonight. ...20Z Update... The previous forecast reasoning (see below) remains the same, and only minor changes were made with this update. ..Weinman.. 12/13/2024 .PREV DISCUSSION... /ISSUED 1030 AM CST Fri Dec 13 2024/ ...Southern/Central Plains into the Ozarks/ArkLaTex... A compact shortwave trough over the Great Basin this morning will move eastward across the southern/central Plains through tonight while gradually amplifying. Related low-level mass response will encourage the northward advance of modified Gulf moisture across parts of the southern/central Plains ahead of a weak surface low and cold front forecast to track from the central High Plains to eastern KS/OK by early Saturday morning. Given the limited/shallow nature of the low-level moisture return, current expectations are for any convection that develops late tonight in the warm advection regime to remain elevated. MUCAPE is generally forecast to remain less than 1000 J/kg, which should tend to limit the prospect for large hail with these elevated thunderstorms. Even so, cold mid-level temperatures associated with the ejecting shortwave trough and sufficient shear through the cloud-bearing layer may support some risk for small hail with the strongest cores. This activity is expected to spread eastward from the southern/central Plains into the Ozarks/ArkLaTex vicinity through the end of the period. ...Northern California... An upper trough will approach the West Coast late tonight into early Saturday morning. Associated low-level warm/moist advection will occur ahead of a weak surface front, with a broad area of precipitation forecast across parts of northern CA and the Pacific Northwest. Gradual cooling of mid-level temperatures will occur as the upper trough approaches, which may support meager MUCAPE across parts of northern CA for the last few hours of the period (early Saturday morning). Isolated lightning flashes may occur with low-topped convection along/near the front, with overall thunderstorm probabilities around 10 percent. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0142 PM CST Fri Dec 13 2024 Valid 132000Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely through tonight. ...20Z Update... The previous forecast reasoning (see below) remains the same, and only minor changes were made with this update. ..Weinman.. 12/13/2024 .PREV DISCUSSION... /ISSUED 1030 AM CST Fri Dec 13 2024/ ...Southern/Central Plains into the Ozarks/ArkLaTex... A compact shortwave trough over the Great Basin this morning will move eastward across the southern/central Plains through tonight while gradually amplifying. Related low-level mass response will encourage the northward advance of modified Gulf moisture across parts of the southern/central Plains ahead of a weak surface low and cold front forecast to track from the central High Plains to eastern KS/OK by early Saturday morning. Given the limited/shallow nature of the low-level moisture return, current expectations are for any convection that develops late tonight in the warm advection regime to remain elevated. MUCAPE is generally forecast to remain less than 1000 J/kg, which should tend to limit the prospect for large hail with these elevated thunderstorms. Even so, cold mid-level temperatures associated with the ejecting shortwave trough and sufficient shear through the cloud-bearing layer may support some risk for small hail with the strongest cores. This activity is expected to spread eastward from the southern/central Plains into the Ozarks/ArkLaTex vicinity through the end of the period. ...Northern California... An upper trough will approach the West Coast late tonight into early Saturday morning. Associated low-level warm/moist advection will occur ahead of a weak surface front, with a broad area of precipitation forecast across parts of northern CA and the Pacific Northwest. Gradual cooling of mid-level temperatures will occur as the upper trough approaches, which may support meager MUCAPE across parts of northern CA for the last few hours of the period (early Saturday morning). Isolated lightning flashes may occur with low-topped convection along/near the front, with overall thunderstorm probabilities around 10 percent. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0142 PM CST Fri Dec 13 2024 Valid 132000Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely through tonight. ...20Z Update... The previous forecast reasoning (see below) remains the same, and only minor changes were made with this update. ..Weinman.. 12/13/2024 .PREV DISCUSSION... /ISSUED 1030 AM CST Fri Dec 13 2024/ ...Southern/Central Plains into the Ozarks/ArkLaTex... A compact shortwave trough over the Great Basin this morning will move eastward across the southern/central Plains through tonight while gradually amplifying. Related low-level mass response will encourage the northward advance of modified Gulf moisture across parts of the southern/central Plains ahead of a weak surface low and cold front forecast to track from the central High Plains to eastern KS/OK by early Saturday morning. Given the limited/shallow nature of the low-level moisture return, current expectations are for any convection that develops late tonight in the warm advection regime to remain elevated. MUCAPE is generally forecast to remain less than 1000 J/kg, which should tend to limit the prospect for large hail with these elevated thunderstorms. Even so, cold mid-level temperatures associated with the ejecting shortwave trough and sufficient shear through the cloud-bearing layer may support some risk for small hail with the strongest cores. This activity is expected to spread eastward from the southern/central Plains into the Ozarks/ArkLaTex vicinity through the end of the period. ...Northern California... An upper trough will approach the West Coast late tonight into early Saturday morning. Associated low-level warm/moist advection will occur ahead of a weak surface front, with a broad area of precipitation forecast across parts of northern CA and the Pacific Northwest. Gradual cooling of mid-level temperatures will occur as the upper trough approaches, which may support meager MUCAPE across parts of northern CA for the last few hours of the period (early Saturday morning). Isolated lightning flashes may occur with low-topped convection along/near the front, with overall thunderstorm probabilities around 10 percent. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0142 PM CST Fri Dec 13 2024 Valid 132000Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely through tonight. ...20Z Update... The previous forecast reasoning (see below) remains the same, and only minor changes were made with this update. ..Weinman.. 12/13/2024 .PREV DISCUSSION... /ISSUED 1030 AM CST Fri Dec 13 2024/ ...Southern/Central Plains into the Ozarks/ArkLaTex... A compact shortwave trough over the Great Basin this morning will move eastward across the southern/central Plains through tonight while gradually amplifying. Related low-level mass response will encourage the northward advance of modified Gulf moisture across parts of the southern/central Plains ahead of a weak surface low and cold front forecast to track from the central High Plains to eastern KS/OK by early Saturday morning. Given the limited/shallow nature of the low-level moisture return, current expectations are for any convection that develops late tonight in the warm advection regime to remain elevated. MUCAPE is generally forecast to remain less than 1000 J/kg, which should tend to limit the prospect for large hail with these elevated thunderstorms. Even so, cold mid-level temperatures associated with the ejecting shortwave trough and sufficient shear through the cloud-bearing layer may support some risk for small hail with the strongest cores. This activity is expected to spread eastward from the southern/central Plains into the Ozarks/ArkLaTex vicinity through the end of the period. ...Northern California... An upper trough will approach the West Coast late tonight into early Saturday morning. Associated low-level warm/moist advection will occur ahead of a weak surface front, with a broad area of precipitation forecast across parts of northern CA and the Pacific Northwest. Gradual cooling of mid-level temperatures will occur as the upper trough approaches, which may support meager MUCAPE across parts of northern CA for the last few hours of the period (early Saturday morning). Isolated lightning flashes may occur with low-topped convection along/near the front, with overall thunderstorm probabilities around 10 percent. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0142 PM CST Fri Dec 13 2024 Valid 132000Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely through tonight. ...20Z Update... The previous forecast reasoning (see below) remains the same, and only minor changes were made with this update. ..Weinman.. 12/13/2024 .PREV DISCUSSION... /ISSUED 1030 AM CST Fri Dec 13 2024/ ...Southern/Central Plains into the Ozarks/ArkLaTex... A compact shortwave trough over the Great Basin this morning will move eastward across the southern/central Plains through tonight while gradually amplifying. Related low-level mass response will encourage the northward advance of modified Gulf moisture across parts of the southern/central Plains ahead of a weak surface low and cold front forecast to track from the central High Plains to eastern KS/OK by early Saturday morning. Given the limited/shallow nature of the low-level moisture return, current expectations are for any convection that develops late tonight in the warm advection regime to remain elevated. MUCAPE is generally forecast to remain less than 1000 J/kg, which should tend to limit the prospect for large hail with these elevated thunderstorms. Even so, cold mid-level temperatures associated with the ejecting shortwave trough and sufficient shear through the cloud-bearing layer may support some risk for small hail with the strongest cores. This activity is expected to spread eastward from the southern/central Plains into the Ozarks/ArkLaTex vicinity through the end of the period. ...Northern California... An upper trough will approach the West Coast late tonight into early Saturday morning. Associated low-level warm/moist advection will occur ahead of a weak surface front, with a broad area of precipitation forecast across parts of northern CA and the Pacific Northwest. Gradual cooling of mid-level temperatures will occur as the upper trough approaches, which may support meager MUCAPE across parts of northern CA for the last few hours of the period (early Saturday morning). Isolated lightning flashes may occur with low-topped convection along/near the front, with overall thunderstorm probabilities around 10 percent. Read more