Severe Storms

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0346 PM CST Wed Dec 20 2023 Valid 221200Z - 281200Z Across the CONUS, amplified and progressive mid-level flow is expected through much of the extended forecast period. Pacific troughing will move inland and continue eastward into the central US starting Friday, while transient ridging over the eastern US will gradually move offshore this weekend. Cool temperatures and unsettled weather are likely over the western and central CONUS with the passage of the upper trough and a surface cold front. Widespread precipitation is expected over the CONUS through the weekend and into next week as the upper-level system moves to the east. Toward the end of the forecast period, another Pacific trough will move onshore over the West Coast as temporary ridging builds over the central US. Onshore flow will support widespread precipitation with cool to mild temperatures. Given the lack of strong winds juxtaposed with warm temperatures and dry fuels, widespread critical fire-weather conditions appear unlikely through the next 7 days. ..Lyons.. 12/20/2023 ...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 0148 PM CST Wed Dec 20 2023 Valid 202000Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms remain possible across parts of southern/central California and over portions of the Southwest. Severe weather is not expected. ...20Z Update... A band of precipitation well east of an upper low over the eastern Pacific will continue to move slowly eastward across parts of coastal central/southern CA this afternoon through tonight. Even though surface temperatures ahead of this band have warmed more than most guidance forecast across coastal portions of Santa Barbara/Ventura counties, modest lapse rates aloft have hindered CG lightning flashes thus far. Nearly unidirectional southerly winds shown on recent VWPs from KVBX and KVTX will continue to limit low/mid-level directional shear, and should hinder potential for greater updraft organization amid weak instability (MLCAPE generally less than 500 J/kg). While isolated strong/gusty convective winds may still occur given the background wind field, overall severe potential still appears low. Isolated thunderstorms will also remain possible this afternoon and early evening across parts of eastern AZ into NM in association with a weak mid-level shortwave trough. ..Gleason.. 12/20/2023 .PREV DISCUSSION... /ISSUED 1025 AM CST Wed Dec 20 2023/ ...Discussion... Low-amplitude ridging aloft will prevail across much of the country today, as eastern U.S. troughing continues to slowly depart the Northeast. The main feature of interest with respect to convective potential remains an upper low off the coast of California, which will continue moving slowly southward. Within the warm conveyor region of this system, and just ahead of a weak surface front moving onshore, a disorganized band of convection is indicated -- the strongest portion of which will gradually move onshore over San Luis Obispo and Santa Barbara Counties over the next few hours. Ahead of this band, onshore instability remains very weak and low-topped -- as evidenced by the overall lack of lightning. This, combined with weak low-level shear precludes any appreciable risk for severe weather, though gusty winds may accompany any stronger convective elements. Elsewhere, sporadic lightning will continue across portions of the Southwest, in conjunction with a weaker mid-level disturbance moving slowly eastward across the Four Corners states. Thunderstorms are not expected across the remainder of the U.S., where surface high pressure and accompanying cool/stable conditions prevail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0148 PM CST Wed Dec 20 2023 Valid 202000Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms remain possible across parts of southern/central California and over portions of the Southwest. Severe weather is not expected. ...20Z Update... A band of precipitation well east of an upper low over the eastern Pacific will continue to move slowly eastward across parts of coastal central/southern CA this afternoon through tonight. Even though surface temperatures ahead of this band have warmed more than most guidance forecast across coastal portions of Santa Barbara/Ventura counties, modest lapse rates aloft have hindered CG lightning flashes thus far. Nearly unidirectional southerly winds shown on recent VWPs from KVBX and KVTX will continue to limit low/mid-level directional shear, and should hinder potential for greater updraft organization amid weak instability (MLCAPE generally less than 500 J/kg). While isolated strong/gusty convective winds may still occur given the background wind field, overall severe potential still appears low. Isolated thunderstorms will also remain possible this afternoon and early evening across parts of eastern AZ into NM in association with a weak mid-level shortwave trough. ..Gleason.. 12/20/2023 .PREV DISCUSSION... /ISSUED 1025 AM CST Wed Dec 20 2023/ ...Discussion... Low-amplitude ridging aloft will prevail across much of the country today, as eastern U.S. troughing continues to slowly depart the Northeast. The main feature of interest with respect to convective potential remains an upper low off the coast of California, which will continue moving slowly southward. Within the warm conveyor region of this system, and just ahead of a weak surface front moving onshore, a disorganized band of convection is indicated -- the strongest portion of which will gradually move onshore over San Luis Obispo and Santa Barbara Counties over the next few hours. Ahead of this band, onshore instability remains very weak and low-topped -- as evidenced by the overall lack of lightning. This, combined with weak low-level shear precludes any appreciable risk for severe weather, though gusty winds may accompany any stronger convective elements. Elsewhere, sporadic lightning will continue across portions of the Southwest, in conjunction with a weaker mid-level disturbance moving slowly eastward across the Four Corners states. Thunderstorms are not expected across the remainder of the U.S., where surface high pressure and accompanying cool/stable conditions prevail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0148 PM CST Wed Dec 20 2023 Valid 202000Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms remain possible across parts of southern/central California and over portions of the Southwest. Severe weather is not expected. ...20Z Update... A band of precipitation well east of an upper low over the eastern Pacific will continue to move slowly eastward across parts of coastal central/southern CA this afternoon through tonight. Even though surface temperatures ahead of this band have warmed more than most guidance forecast across coastal portions of Santa Barbara/Ventura counties, modest lapse rates aloft have hindered CG lightning flashes thus far. Nearly unidirectional southerly winds shown on recent VWPs from KVBX and KVTX will continue to limit low/mid-level directional shear, and should hinder potential for greater updraft organization amid weak instability (MLCAPE generally less than 500 J/kg). While isolated strong/gusty convective winds may still occur given the background wind field, overall severe potential still appears low. Isolated thunderstorms will also remain possible this afternoon and early evening across parts of eastern AZ into NM in association with a weak mid-level shortwave trough. ..Gleason.. 12/20/2023 .PREV DISCUSSION... /ISSUED 1025 AM CST Wed Dec 20 2023/ ...Discussion... Low-amplitude ridging aloft will prevail across much of the country today, as eastern U.S. troughing continues to slowly depart the Northeast. The main feature of interest with respect to convective potential remains an upper low off the coast of California, which will continue moving slowly southward. Within the warm conveyor region of this system, and just ahead of a weak surface front moving onshore, a disorganized band of convection is indicated -- the strongest portion of which will gradually move onshore over San Luis Obispo and Santa Barbara Counties over the next few hours. Ahead of this band, onshore instability remains very weak and low-topped -- as evidenced by the overall lack of lightning. This, combined with weak low-level shear precludes any appreciable risk for severe weather, though gusty winds may accompany any stronger convective elements. Elsewhere, sporadic lightning will continue across portions of the Southwest, in conjunction with a weaker mid-level disturbance moving slowly eastward across the Four Corners states. Thunderstorms are not expected across the remainder of the U.S., where surface high pressure and accompanying cool/stable conditions prevail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0148 PM CST Wed Dec 20 2023 Valid 202000Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms remain possible across parts of southern/central California and over portions of the Southwest. Severe weather is not expected. ...20Z Update... A band of precipitation well east of an upper low over the eastern Pacific will continue to move slowly eastward across parts of coastal central/southern CA this afternoon through tonight. Even though surface temperatures ahead of this band have warmed more than most guidance forecast across coastal portions of Santa Barbara/Ventura counties, modest lapse rates aloft have hindered CG lightning flashes thus far. Nearly unidirectional southerly winds shown on recent VWPs from KVBX and KVTX will continue to limit low/mid-level directional shear, and should hinder potential for greater updraft organization amid weak instability (MLCAPE generally less than 500 J/kg). While isolated strong/gusty convective winds may still occur given the background wind field, overall severe potential still appears low. Isolated thunderstorms will also remain possible this afternoon and early evening across parts of eastern AZ into NM in association with a weak mid-level shortwave trough. ..Gleason.. 12/20/2023 .PREV DISCUSSION... /ISSUED 1025 AM CST Wed Dec 20 2023/ ...Discussion... Low-amplitude ridging aloft will prevail across much of the country today, as eastern U.S. troughing continues to slowly depart the Northeast. The main feature of interest with respect to convective potential remains an upper low off the coast of California, which will continue moving slowly southward. Within the warm conveyor region of this system, and just ahead of a weak surface front moving onshore, a disorganized band of convection is indicated -- the strongest portion of which will gradually move onshore over San Luis Obispo and Santa Barbara Counties over the next few hours. Ahead of this band, onshore instability remains very weak and low-topped -- as evidenced by the overall lack of lightning. This, combined with weak low-level shear precludes any appreciable risk for severe weather, though gusty winds may accompany any stronger convective elements. Elsewhere, sporadic lightning will continue across portions of the Southwest, in conjunction with a weaker mid-level disturbance moving slowly eastward across the Four Corners states. Thunderstorms are not expected across the remainder of the U.S., where surface high pressure and accompanying cool/stable conditions prevail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0148 PM CST Wed Dec 20 2023 Valid 202000Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms remain possible across parts of southern/central California and over portions of the Southwest. Severe weather is not expected. ...20Z Update... A band of precipitation well east of an upper low over the eastern Pacific will continue to move slowly eastward across parts of coastal central/southern CA this afternoon through tonight. Even though surface temperatures ahead of this band have warmed more than most guidance forecast across coastal portions of Santa Barbara/Ventura counties, modest lapse rates aloft have hindered CG lightning flashes thus far. Nearly unidirectional southerly winds shown on recent VWPs from KVBX and KVTX will continue to limit low/mid-level directional shear, and should hinder potential for greater updraft organization amid weak instability (MLCAPE generally less than 500 J/kg). While isolated strong/gusty convective winds may still occur given the background wind field, overall severe potential still appears low. Isolated thunderstorms will also remain possible this afternoon and early evening across parts of eastern AZ into NM in association with a weak mid-level shortwave trough. ..Gleason.. 12/20/2023 .PREV DISCUSSION... /ISSUED 1025 AM CST Wed Dec 20 2023/ ...Discussion... Low-amplitude ridging aloft will prevail across much of the country today, as eastern U.S. troughing continues to slowly depart the Northeast. The main feature of interest with respect to convective potential remains an upper low off the coast of California, which will continue moving slowly southward. Within the warm conveyor region of this system, and just ahead of a weak surface front moving onshore, a disorganized band of convection is indicated -- the strongest portion of which will gradually move onshore over San Luis Obispo and Santa Barbara Counties over the next few hours. Ahead of this band, onshore instability remains very weak and low-topped -- as evidenced by the overall lack of lightning. This, combined with weak low-level shear precludes any appreciable risk for severe weather, though gusty winds may accompany any stronger convective elements. Elsewhere, sporadic lightning will continue across portions of the Southwest, in conjunction with a weaker mid-level disturbance moving slowly eastward across the Four Corners states. Thunderstorms are not expected across the remainder of the U.S., where surface high pressure and accompanying cool/stable conditions prevail. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0134 PM CST Wed Dec 20 2023 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... Increasing precipitation chances and cool to mild temperatures will keep fire-weather concerns minimal over much of the CONUS. See the previous discussion. ..Lyons.. 12/20/2023 .PREV DISCUSSION... /ISSUED 1250 AM CST Wed Dec 20 2023/ ...Synopsis... Mid-level troughs will progress across the western and central CONUS tomorrow/Thursday, supporting continued low-level moisture return and precipitation across the Plains as cooler air remains in place over the eastern CONUS and Intermountain West. When also considering the continued precipitation accumulations over California, significant wildfire-spread potential continues to appear negligible over most of the U.S. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0134 PM CST Wed Dec 20 2023 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... Increasing precipitation chances and cool to mild temperatures will keep fire-weather concerns minimal over much of the CONUS. See the previous discussion. ..Lyons.. 12/20/2023 .PREV DISCUSSION... /ISSUED 1250 AM CST Wed Dec 20 2023/ ...Synopsis... Mid-level troughs will progress across the western and central CONUS tomorrow/Thursday, supporting continued low-level moisture return and precipitation across the Plains as cooler air remains in place over the eastern CONUS and Intermountain West. When also considering the continued precipitation accumulations over California, significant wildfire-spread potential continues to appear negligible over most of the U.S. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0134 PM CST Wed Dec 20 2023 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... Increasing precipitation chances and cool to mild temperatures will keep fire-weather concerns minimal over much of the CONUS. See the previous discussion. ..Lyons.. 12/20/2023 .PREV DISCUSSION... /ISSUED 1250 AM CST Wed Dec 20 2023/ ...Synopsis... Mid-level troughs will progress across the western and central CONUS tomorrow/Thursday, supporting continued low-level moisture return and precipitation across the Plains as cooler air remains in place over the eastern CONUS and Intermountain West. When also considering the continued precipitation accumulations over California, significant wildfire-spread potential continues to appear negligible over most of the U.S. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0134 PM CST Wed Dec 20 2023 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... Increasing precipitation chances and cool to mild temperatures will keep fire-weather concerns minimal over much of the CONUS. See the previous discussion. ..Lyons.. 12/20/2023 .PREV DISCUSSION... /ISSUED 1250 AM CST Wed Dec 20 2023/ ...Synopsis... Mid-level troughs will progress across the western and central CONUS tomorrow/Thursday, supporting continued low-level moisture return and precipitation across the Plains as cooler air remains in place over the eastern CONUS and Intermountain West. When also considering the continued precipitation accumulations over California, significant wildfire-spread potential continues to appear negligible over most of the U.S. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0134 PM CST Wed Dec 20 2023 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... Increasing precipitation chances and cool to mild temperatures will keep fire-weather concerns minimal over much of the CONUS. See the previous discussion. ..Lyons.. 12/20/2023 .PREV DISCUSSION... /ISSUED 1250 AM CST Wed Dec 20 2023/ ...Synopsis... Mid-level troughs will progress across the western and central CONUS tomorrow/Thursday, supporting continued low-level moisture return and precipitation across the Plains as cooler air remains in place over the eastern CONUS and Intermountain West. When also considering the continued precipitation accumulations over California, significant wildfire-spread potential continues to appear negligible over most of the U.S. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1100 AM CST Wed Dec 20 2023 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms should occur Thursday across parts of central/southern California and southern Arizona. Severe thunderstorms are not expected. ...Synopsis and Discussion... An upper low should be centered well off the coast of southern CA early Thursday morning. This low is expected to drift gradually southward through the day, before moving more eastward towards the coast overnight and into Friday morning. Large-scale ascent, ample mid-level moisture, and cold mid-level temperatures associated with this upper low should encourage isolated thunderstorms along and near the central/southern CA coast through the period. As the low moves gradually eastward, showers and occasional thunderstorms are forecast to expand eastward across southern Arizona through early Friday morning. Weak instability should preclude a meaningful threat for severe thunderstorms across these areas. ..Gleason.. 12/20/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1100 AM CST Wed Dec 20 2023 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms should occur Thursday across parts of central/southern California and southern Arizona. Severe thunderstorms are not expected. ...Synopsis and Discussion... An upper low should be centered well off the coast of southern CA early Thursday morning. This low is expected to drift gradually southward through the day, before moving more eastward towards the coast overnight and into Friday morning. Large-scale ascent, ample mid-level moisture, and cold mid-level temperatures associated with this upper low should encourage isolated thunderstorms along and near the central/southern CA coast through the period. As the low moves gradually eastward, showers and occasional thunderstorms are forecast to expand eastward across southern Arizona through early Friday morning. Weak instability should preclude a meaningful threat for severe thunderstorms across these areas. ..Gleason.. 12/20/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1100 AM CST Wed Dec 20 2023 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms should occur Thursday across parts of central/southern California and southern Arizona. Severe thunderstorms are not expected. ...Synopsis and Discussion... An upper low should be centered well off the coast of southern CA early Thursday morning. This low is expected to drift gradually southward through the day, before moving more eastward towards the coast overnight and into Friday morning. Large-scale ascent, ample mid-level moisture, and cold mid-level temperatures associated with this upper low should encourage isolated thunderstorms along and near the central/southern CA coast through the period. As the low moves gradually eastward, showers and occasional thunderstorms are forecast to expand eastward across southern Arizona through early Friday morning. Weak instability should preclude a meaningful threat for severe thunderstorms across these areas. ..Gleason.. 12/20/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1100 AM CST Wed Dec 20 2023 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms should occur Thursday across parts of central/southern California and southern Arizona. Severe thunderstorms are not expected. ...Synopsis and Discussion... An upper low should be centered well off the coast of southern CA early Thursday morning. This low is expected to drift gradually southward through the day, before moving more eastward towards the coast overnight and into Friday morning. Large-scale ascent, ample mid-level moisture, and cold mid-level temperatures associated with this upper low should encourage isolated thunderstorms along and near the central/southern CA coast through the period. As the low moves gradually eastward, showers and occasional thunderstorms are forecast to expand eastward across southern Arizona through early Friday morning. Weak instability should preclude a meaningful threat for severe thunderstorms across these areas. ..Gleason.. 12/20/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1100 AM CST Wed Dec 20 2023 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms should occur Thursday across parts of central/southern California and southern Arizona. Severe thunderstorms are not expected. ...Synopsis and Discussion... An upper low should be centered well off the coast of southern CA early Thursday morning. This low is expected to drift gradually southward through the day, before moving more eastward towards the coast overnight and into Friday morning. Large-scale ascent, ample mid-level moisture, and cold mid-level temperatures associated with this upper low should encourage isolated thunderstorms along and near the central/southern CA coast through the period. As the low moves gradually eastward, showers and occasional thunderstorms are forecast to expand eastward across southern Arizona through early Friday morning. Weak instability should preclude a meaningful threat for severe thunderstorms across these areas. ..Gleason.. 12/20/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1100 AM CST Wed Dec 20 2023 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms should occur Thursday across parts of central/southern California and southern Arizona. Severe thunderstorms are not expected. ...Synopsis and Discussion... An upper low should be centered well off the coast of southern CA early Thursday morning. This low is expected to drift gradually southward through the day, before moving more eastward towards the coast overnight and into Friday morning. Large-scale ascent, ample mid-level moisture, and cold mid-level temperatures associated with this upper low should encourage isolated thunderstorms along and near the central/southern CA coast through the period. As the low moves gradually eastward, showers and occasional thunderstorms are forecast to expand eastward across southern Arizona through early Friday morning. Weak instability should preclude a meaningful threat for severe thunderstorms across these areas. ..Gleason.. 12/20/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1025 AM CST Wed Dec 20 2023 Valid 201630Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms will be possible across parts of southern/central California and over portions of the Southwest. Severe weather is not expected. ...Discussion... Low-amplitude ridging aloft will prevail across much of the country today, as eastern U.S. troughing continues to slowly depart the Northeast. The main feature of interest with respect to convective potential remains an upper low off the coast of California, which will continue moving slowly southward. Within the warm conveyor region of this system, and just ahead of a weak surface front moving onshore, a disorganized band of convection is indicated -- the strongest portion of which will gradually move onshore over San Luis Obispo and Santa Barbara Counties over the next few hours. Ahead of this band, onshore instability remains very weak and low-topped -- as evidenced by the overall lack of lightning. This, combined with weak low-level shear precludes any appreciable risk for severe weather, though gusty winds may accompany any stronger convective elements. Elsewhere, sporadic lightning will continue across portions of the Southwest, in conjunction with a weaker mid-level disturbance moving slowly eastward across the Four Corners states. Thunderstorms are not expected across the remainder of the U.S., where surface high pressure and accompanying cool/stable conditions prevail. ..Goss/Thornton.. 12/20/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1025 AM CST Wed Dec 20 2023 Valid 201630Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms will be possible across parts of southern/central California and over portions of the Southwest. Severe weather is not expected. ...Discussion... Low-amplitude ridging aloft will prevail across much of the country today, as eastern U.S. troughing continues to slowly depart the Northeast. The main feature of interest with respect to convective potential remains an upper low off the coast of California, which will continue moving slowly southward. Within the warm conveyor region of this system, and just ahead of a weak surface front moving onshore, a disorganized band of convection is indicated -- the strongest portion of which will gradually move onshore over San Luis Obispo and Santa Barbara Counties over the next few hours. Ahead of this band, onshore instability remains very weak and low-topped -- as evidenced by the overall lack of lightning. This, combined with weak low-level shear precludes any appreciable risk for severe weather, though gusty winds may accompany any stronger convective elements. Elsewhere, sporadic lightning will continue across portions of the Southwest, in conjunction with a weaker mid-level disturbance moving slowly eastward across the Four Corners states. Thunderstorms are not expected across the remainder of the U.S., where surface high pressure and accompanying cool/stable conditions prevail. ..Goss/Thornton.. 12/20/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1025 AM CST Wed Dec 20 2023 Valid 201630Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms will be possible across parts of southern/central California and over portions of the Southwest. Severe weather is not expected. ...Discussion... Low-amplitude ridging aloft will prevail across much of the country today, as eastern U.S. troughing continues to slowly depart the Northeast. The main feature of interest with respect to convective potential remains an upper low off the coast of California, which will continue moving slowly southward. Within the warm conveyor region of this system, and just ahead of a weak surface front moving onshore, a disorganized band of convection is indicated -- the strongest portion of which will gradually move onshore over San Luis Obispo and Santa Barbara Counties over the next few hours. Ahead of this band, onshore instability remains very weak and low-topped -- as evidenced by the overall lack of lightning. This, combined with weak low-level shear precludes any appreciable risk for severe weather, though gusty winds may accompany any stronger convective elements. Elsewhere, sporadic lightning will continue across portions of the Southwest, in conjunction with a weaker mid-level disturbance moving slowly eastward across the Four Corners states. Thunderstorms are not expected across the remainder of the U.S., where surface high pressure and accompanying cool/stable conditions prevail. ..Goss/Thornton.. 12/20/2023 Read more