Severe Storms

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1113 PM CST Mon Dec 18 2023 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms are possible across northern California. ...California... An area of modest midlevel height falls will spread south along the CA Coast and adjacent offshore areas as an upper low digs to near 36N/127W by the end of the period. While the primary surface front should not advance inland, weak boundary-layer heating should contribute to weak surface-based buoyancy across portions of northern CA within favorable high-level diffluent flow aloft. Forecast soundings exhibit SBCAPE around 200 J/kg by early afternoon which may be adequate for lifted parcels to approach levels necessary for lightning discharge. Later in the period, near-frontal convection will approach the CA Coast, and this activity may also pose some risk for lightning within the more robust updrafts, although it too should remain rather isolated. ..Darrow/Squitieri.. 12/19/2023 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0645 PM CST Mon Dec 18 2023 Valid 190100Z - 191200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorm potential is low tonight. ...01z Update... Midlevel speed max is translating inland across northern CA this evening. Associated short-wave trough will deamplify as it ejects into OR later tonight. Very little/no lightning has been observed with weak convection ahead of this feature. 00z sounding from OAK exhibits poor lapse rates with meager buoyancy. While some large-scale forcing for ascent will be noted early this evening, meaningful destabilization is not expected and the risk for lightning is very low. ..Darrow.. 12/19/2023 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0645 PM CST Mon Dec 18 2023 Valid 190100Z - 191200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorm potential is low tonight. ...01z Update... Midlevel speed max is translating inland across northern CA this evening. Associated short-wave trough will deamplify as it ejects into OR later tonight. Very little/no lightning has been observed with weak convection ahead of this feature. 00z sounding from OAK exhibits poor lapse rates with meager buoyancy. While some large-scale forcing for ascent will be noted early this evening, meaningful destabilization is not expected and the risk for lightning is very low. ..Darrow.. 12/19/2023 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0645 PM CST Mon Dec 18 2023 Valid 190100Z - 191200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorm potential is low tonight. ...01z Update... Midlevel speed max is translating inland across northern CA this evening. Associated short-wave trough will deamplify as it ejects into OR later tonight. Very little/no lightning has been observed with weak convection ahead of this feature. 00z sounding from OAK exhibits poor lapse rates with meager buoyancy. While some large-scale forcing for ascent will be noted early this evening, meaningful destabilization is not expected and the risk for lightning is very low. ..Darrow.. 12/19/2023 Read more

No watches are valid as of Mon Dec 18 23:56:02 UTC 2023.

No Mesoscale Discussions are in effect as of Mon Dec 18 23:56:02 UTC 2023.

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0334 PM CST Mon Dec 18 2023 Valid 201200Z - 261200Z Mid-level flow is expected to remain amplified and progressive with period of unsettled weather possible through the extended forecast period. Transient ridging will slowly build over the central US, keeping winds light and temperatures cool to mild. A deep trough will persist off the Atlantic Coast through the next several days before it slowly departs to the east. At the same time, a cut off low and shortwave trough over the eastern Pacific will support continuous onshore flow of moisture across parts of the western US through the end of the week. Late in the work week and into the weekend, the western US troughing will begin to move eastward, bringing cool and unsettled weather to the central CONUS through the end of the forecast period. Widespread precipitation and winter weather are expected to develop over the Western and central US into the weekend and early next week. To the east, surface high pressure will strengthen in the wake of the departing Atlantic trough keeping winds relatively light and temperatures cool. Some low RH is possible over parts of the Southeast into the weekend, but winds are expected to remain very light. With mild temperatures, modest winds, and widespread precipitation expected over much of the US, significant fire-weather conditions appear unlikely through the next 7 days. ..Lyons.. 12/18/2023 ...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 0334 PM CST Mon Dec 18 2023 Valid 201200Z - 261200Z Mid-level flow is expected to remain amplified and progressive with period of unsettled weather possible through the extended forecast period. Transient ridging will slowly build over the central US, keeping winds light and temperatures cool to mild. A deep trough will persist off the Atlantic Coast through the next several days before it slowly departs to the east. At the same time, a cut off low and shortwave trough over the eastern Pacific will support continuous onshore flow of moisture across parts of the western US through the end of the week. Late in the work week and into the weekend, the western US troughing will begin to move eastward, bringing cool and unsettled weather to the central CONUS through the end of the forecast period. Widespread precipitation and winter weather are expected to develop over the Western and central US into the weekend and early next week. To the east, surface high pressure will strengthen in the wake of the departing Atlantic trough keeping winds relatively light and temperatures cool. Some low RH is possible over parts of the Southeast into the weekend, but winds are expected to remain very light. With mild temperatures, modest winds, and widespread precipitation expected over much of the US, significant fire-weather conditions appear unlikely through the next 7 days. ..Lyons.. 12/18/2023 ...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 0334 PM CST Mon Dec 18 2023 Valid 201200Z - 261200Z Mid-level flow is expected to remain amplified and progressive with period of unsettled weather possible through the extended forecast period. Transient ridging will slowly build over the central US, keeping winds light and temperatures cool to mild. A deep trough will persist off the Atlantic Coast through the next several days before it slowly departs to the east. At the same time, a cut off low and shortwave trough over the eastern Pacific will support continuous onshore flow of moisture across parts of the western US through the end of the week. Late in the work week and into the weekend, the western US troughing will begin to move eastward, bringing cool and unsettled weather to the central CONUS through the end of the forecast period. Widespread precipitation and winter weather are expected to develop over the Western and central US into the weekend and early next week. To the east, surface high pressure will strengthen in the wake of the departing Atlantic trough keeping winds relatively light and temperatures cool. Some low RH is possible over parts of the Southeast into the weekend, but winds are expected to remain very light. With mild temperatures, modest winds, and widespread precipitation expected over much of the US, significant fire-weather conditions appear unlikely through the next 7 days. ..Lyons.. 12/18/2023 ...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 0334 PM CST Mon Dec 18 2023 Valid 201200Z - 261200Z Mid-level flow is expected to remain amplified and progressive with period of unsettled weather possible through the extended forecast period. Transient ridging will slowly build over the central US, keeping winds light and temperatures cool to mild. A deep trough will persist off the Atlantic Coast through the next several days before it slowly departs to the east. At the same time, a cut off low and shortwave trough over the eastern Pacific will support continuous onshore flow of moisture across parts of the western US through the end of the week. Late in the work week and into the weekend, the western US troughing will begin to move eastward, bringing cool and unsettled weather to the central CONUS through the end of the forecast period. Widespread precipitation and winter weather are expected to develop over the Western and central US into the weekend and early next week. To the east, surface high pressure will strengthen in the wake of the departing Atlantic trough keeping winds relatively light and temperatures cool. Some low RH is possible over parts of the Southeast into the weekend, but winds are expected to remain very light. With mild temperatures, modest winds, and widespread precipitation expected over much of the US, significant fire-weather conditions appear unlikely through the next 7 days. ..Lyons.. 12/18/2023 ...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 0136 PM CST Mon Dec 18 2023 Valid 182000Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is expected to remain low the remainder of this afternoon into tonight. ...Synopsis... Showers will continue across New England into this evening ahead of the elongated surface low currently from near Long Island toward the St. Lawrence Valley. Gusty surface winds also will persist given the strong pressure gradient and intense low-level winds just above the surface. However, any deeper convective elements will remain offshore, and thunderstorm potential will be low over land. Given deeper convection has pushed east, severe probabilities have been removed from southern New England. Isolated thunderstorms are still possible this afternoon across parts of central/northern CA, but chances should diminish by evening. Severe storms are not expected. ..Leitman.. 12/18/2023 .PREV DISCUSSION... /ISSUED 1013 AM CST Mon Dec 18 2023/ ...Southeastern New England.. A narrow/forced band of convection is moving quickly eastward across southeastern Massachusetts and Rhode Island at this time, immediately ahead of a strong, northeastward-moving mid-level vort max depicted by water vapor imagery just south of Long Island. While cool surface temperatures have prohibited surface-based instability in most areas, a small area of warmer (low 60s) boundary layer is indicated over far southeastern New England (southeast Massachusetts). As such, minor enhancement of the intensity of the convective band may occur over the next couple of hours, possibly resulting in some mechanical downward transport of intense low-level flow observed across this area. This could result in gusts slightly above the already above-severe level gradient gusts that are ongoing, until convection moves offshore later this afternoon. For additional short-term information, please refer to SWOMCD #2337. ...California... Thunderstorms associated with an inland-moving eastern Pacific short-wave trough have diminished across California, but a few additional lightning flashes remain possible this afternoon/ evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0136 PM CST Mon Dec 18 2023 Valid 182000Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is expected to remain low the remainder of this afternoon into tonight. ...Synopsis... Showers will continue across New England into this evening ahead of the elongated surface low currently from near Long Island toward the St. Lawrence Valley. Gusty surface winds also will persist given the strong pressure gradient and intense low-level winds just above the surface. However, any deeper convective elements will remain offshore, and thunderstorm potential will be low over land. Given deeper convection has pushed east, severe probabilities have been removed from southern New England. Isolated thunderstorms are still possible this afternoon across parts of central/northern CA, but chances should diminish by evening. Severe storms are not expected. ..Leitman.. 12/18/2023 .PREV DISCUSSION... /ISSUED 1013 AM CST Mon Dec 18 2023/ ...Southeastern New England.. A narrow/forced band of convection is moving quickly eastward across southeastern Massachusetts and Rhode Island at this time, immediately ahead of a strong, northeastward-moving mid-level vort max depicted by water vapor imagery just south of Long Island. While cool surface temperatures have prohibited surface-based instability in most areas, a small area of warmer (low 60s) boundary layer is indicated over far southeastern New England (southeast Massachusetts). As such, minor enhancement of the intensity of the convective band may occur over the next couple of hours, possibly resulting in some mechanical downward transport of intense low-level flow observed across this area. This could result in gusts slightly above the already above-severe level gradient gusts that are ongoing, until convection moves offshore later this afternoon. For additional short-term information, please refer to SWOMCD #2337. ...California... Thunderstorms associated with an inland-moving eastern Pacific short-wave trough have diminished across California, but a few additional lightning flashes remain possible this afternoon/ evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0136 PM CST Mon Dec 18 2023 Valid 182000Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is expected to remain low the remainder of this afternoon into tonight. ...Synopsis... Showers will continue across New England into this evening ahead of the elongated surface low currently from near Long Island toward the St. Lawrence Valley. Gusty surface winds also will persist given the strong pressure gradient and intense low-level winds just above the surface. However, any deeper convective elements will remain offshore, and thunderstorm potential will be low over land. Given deeper convection has pushed east, severe probabilities have been removed from southern New England. Isolated thunderstorms are still possible this afternoon across parts of central/northern CA, but chances should diminish by evening. Severe storms are not expected. ..Leitman.. 12/18/2023 .PREV DISCUSSION... /ISSUED 1013 AM CST Mon Dec 18 2023/ ...Southeastern New England.. A narrow/forced band of convection is moving quickly eastward across southeastern Massachusetts and Rhode Island at this time, immediately ahead of a strong, northeastward-moving mid-level vort max depicted by water vapor imagery just south of Long Island. While cool surface temperatures have prohibited surface-based instability in most areas, a small area of warmer (low 60s) boundary layer is indicated over far southeastern New England (southeast Massachusetts). As such, minor enhancement of the intensity of the convective band may occur over the next couple of hours, possibly resulting in some mechanical downward transport of intense low-level flow observed across this area. This could result in gusts slightly above the already above-severe level gradient gusts that are ongoing, until convection moves offshore later this afternoon. For additional short-term information, please refer to SWOMCD #2337. ...California... Thunderstorms associated with an inland-moving eastern Pacific short-wave trough have diminished across California, but a few additional lightning flashes remain possible this afternoon/ evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0136 PM CST Mon Dec 18 2023 Valid 182000Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is expected to remain low the remainder of this afternoon into tonight. ...Synopsis... Showers will continue across New England into this evening ahead of the elongated surface low currently from near Long Island toward the St. Lawrence Valley. Gusty surface winds also will persist given the strong pressure gradient and intense low-level winds just above the surface. However, any deeper convective elements will remain offshore, and thunderstorm potential will be low over land. Given deeper convection has pushed east, severe probabilities have been removed from southern New England. Isolated thunderstorms are still possible this afternoon across parts of central/northern CA, but chances should diminish by evening. Severe storms are not expected. ..Leitman.. 12/18/2023 .PREV DISCUSSION... /ISSUED 1013 AM CST Mon Dec 18 2023/ ...Southeastern New England.. A narrow/forced band of convection is moving quickly eastward across southeastern Massachusetts and Rhode Island at this time, immediately ahead of a strong, northeastward-moving mid-level vort max depicted by water vapor imagery just south of Long Island. While cool surface temperatures have prohibited surface-based instability in most areas, a small area of warmer (low 60s) boundary layer is indicated over far southeastern New England (southeast Massachusetts). As such, minor enhancement of the intensity of the convective band may occur over the next couple of hours, possibly resulting in some mechanical downward transport of intense low-level flow observed across this area. This could result in gusts slightly above the already above-severe level gradient gusts that are ongoing, until convection moves offshore later this afternoon. For additional short-term information, please refer to SWOMCD #2337. ...California... Thunderstorms associated with an inland-moving eastern Pacific short-wave trough have diminished across California, but a few additional lightning flashes remain possible this afternoon/ evening. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1254 PM CST Mon Dec 18 2023 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... Fire-weather concerns are minimal. See the previous discussion. ..Lyons.. 12/18/2023 .PREV DISCUSSION... /ISSUED 0147 AM CST Mon Dec 18 2023/ ...Synopsis... A mid-level trough will meander along the West Coast as upper ridging persists from the Interior West toward the Appalachians tomorrow/Tuesday. While surface lee troughing is expected across the High Plains, surface high pressure and associated cooler air should dominate over the rest of the CONUS. Similar to Day 1, quiescent fire weather conditions are expected over 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 1254 PM CST Mon Dec 18 2023 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... Fire-weather concerns are minimal. See the previous discussion. ..Lyons.. 12/18/2023 .PREV DISCUSSION... /ISSUED 0147 AM CST Mon Dec 18 2023/ ...Synopsis... A mid-level trough will meander along the West Coast as upper ridging persists from the Interior West toward the Appalachians tomorrow/Tuesday. While surface lee troughing is expected across the High Plains, surface high pressure and associated cooler air should dominate over the rest of the CONUS. Similar to Day 1, quiescent fire weather conditions are expected over 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 1254 PM CST Mon Dec 18 2023 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... Fire-weather concerns are minimal. See the previous discussion. ..Lyons.. 12/18/2023 .PREV DISCUSSION... /ISSUED 0147 AM CST Mon Dec 18 2023/ ...Synopsis... A mid-level trough will meander along the West Coast as upper ridging persists from the Interior West toward the Appalachians tomorrow/Tuesday. While surface lee troughing is expected across the High Plains, surface high pressure and associated cooler air should dominate over the rest of the CONUS. Similar to Day 1, quiescent fire weather conditions are expected over 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 1254 PM CST Mon Dec 18 2023 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... Fire-weather concerns are minimal. See the previous discussion. ..Lyons.. 12/18/2023 .PREV DISCUSSION... /ISSUED 0147 AM CST Mon Dec 18 2023/ ...Synopsis... A mid-level trough will meander along the West Coast as upper ridging persists from the Interior West toward the Appalachians tomorrow/Tuesday. While surface lee troughing is expected across the High Plains, surface high pressure and associated cooler air should dominate over the rest of the CONUS. Similar to Day 1, quiescent fire weather conditions are expected over 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 1254 PM CST Mon Dec 18 2023 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... Fire-weather concerns are minimal. See the previous discussion. ..Lyons.. 12/18/2023 .PREV DISCUSSION... /ISSUED 0147 AM CST Mon Dec 18 2023/ ...Synopsis... A mid-level trough will meander along the West Coast as upper ridging persists from the Interior West toward the Appalachians tomorrow/Tuesday. While surface lee troughing is expected across the High Plains, surface high pressure and associated cooler air should dominate over the rest of the CONUS. Similar to Day 1, quiescent fire weather conditions are expected over the U.S. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 2337 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF EASTERN MASSACHUSETTS
Mesoscale Discussion 2337 NWS Storm Prediction Center Norman OK 0957 AM CST Mon Dec 18 2023 Areas affected...parts of eastern Massachusetts Concerning...Severe potential...Watch unlikely Valid 181557Z - 181830Z Probability of Watch Issuance...5 percent SUMMARY...Wind gusts may be further enhanced by a line of low-topped convection and heavy rain as it moves across eastern Massachusetts. DISCUSSION...A line of low-topped convection with little to no lightning is currently swinging east across southern New England, where a non-convective high wind event is ongoing with numerous measured gusts over 50 kt. Surface analysis shows relatively cool boundary layer temperatures over coastal areas as water temperatures are in the mid to upper 40s F. However, surface temperatures of 61-65 F exist from Boston southward due to longer wind trajectories over land. As such, a small pocket of higher theta-e exists in this area. Given the extreme wind fields just off the surface, this slightly warmer air could potentially augment surface gusts as the shallow convective line moves through. ..Jewell/Goss.. 12/18/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BOX... LAT...LON 41186994 41287047 41267093 41657119 42007137 42177145 42397131 42397097 42167048 42127007 41836982 41186994 Read more