Severe Storms

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1016 AM CST Wed Dec 21 2022 Valid 211700Z - 221200Z The previous forecast (see below) remains on track, with no changes or additions made. ..Squitieri.. 12/21/2022 .PREV DISCUSSION... /ISSUED 0142 AM CST Wed Dec 21 2022/ ...Synopsis... A large-scale trough will amplify over the central CONUS, as an intense mid/upper-level speed max overspreads the western states. The strong midlevel flow (60-75 kt at 500 mb) perpendicular to the central Rockies will support a deepening lee cyclone over eastern CO during the afternoon, before a strong cold front advances southward across the central/southern Rockies and adjacent Plains into the overnight hours. ...I-25 Corridor in south-central CO into northeast NM... As the aforementioned mid/upper-level speed max intercepts the central/southern Rockies, 15-25 mph sustained westerly surface winds (with 40-50 mph gusts) should develop in the immediate lee of the high terrain from south-central CO into northeast NM. Here, strong downslope warming/drying should yield 15-25 percent RH during the afternoon. The combination of strong/gusty winds and low RH atop receptive fuels will support elevated conditions, primarily along the I-25 corridor during the afternoon hours. While locally critical conditions are possible (especially through gap-flow areas), these conditions are too localized for Critical highlights. Strong/gusty winds and low RH are also expected north of the Elevated area along the Front Range foothills in north-central CO, though the localized nature of these conditions precludes highlights. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1013 AM CST Wed Dec 21 2022 Valid 211630Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast today and tonight. ...Synopsis... Mid-morning surface observations and satellite imagery reveal a cold front meandering southward along the FL peninsula with a weak, broad surface low off the FL east coast. Despite somewhat weak inhibition sampled in the MFL and KEY RAOBs, subsidence overspreading the region (evident in low-level water-vapor imagery) has stunted any convective development thus far. However, daytime heating should foster gradual destabilization through the day, and weak forcing along the front may be adequate for isolated convection across south FL. While strong mid to upper-level flow will continue to support nearly 50 knots of 0-6 km bulk shear, weak CAPE profiles of the most-unstable layer coupled with increasing mid-level dry air suggests updraft strengths will remain modest and will limit the potential for organized severe convection. The low off the FL coast is expected to shift north into the Carolinas during the overnight hours in response to increasing 850-700 mb warm advection. Warming, saturation, and lift within this layer will steepen mid-level lapse rates and support isolated to scattered thunderstorm development overnight across the Carolinas. Deeper, more robust convection appears most probable along the SC coast where warmer low-level temperatures will support deeper parcel trajectories and effective shear values near 30 knots. A few instances of small hail and/or strong wind gusts are possible, but the overall severe threat is expected to remain low. ..Moore/Grams.. 12/21/2022 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1212 PM CST Tue Dec 20 2022 Valid 211200Z - 221200Z The main change made in the Day 2 fire weather outlook update was to trim the northern extent of the Elevated area to account for snow cover over parts of the region. Otherwise, the previous forecast (see below) remains on track. ..Squitieri.. 12/20/2022 .PREV DISCUSSION... /ISSUED 0157 AM CST Tue Dec 20 2022/ ...Synopsis... A large-scale trough will amplify across the central CONUS, as an intense mid/upper-level speed max dives southeastward across the western states. As the strong west-northwesterly midlevel flow impinges on the central Rockies, a lee cyclone will deepen over eastern CO, before a strong cold front overspreads the central/southern Rockies and adjacent Plains into the overnight hours. ...I-25 Corridor in south-central CO and northeast NM... As the strong west-northwesterly midlevel flow (60-75+ kt at 500-mb) intercepts the central/southern Rockies, strong/gusty surface winds should develop in the immediate lee of the higher terrain from CO into NM. While cool surface temperatures in north-central CO should generally limit the fire-weather threat, downslope warming/drying amid a slightly warmer airmass should yield lower/middle 50s surface temperatures along the I-25 corridor from south-central CO into northeast NM. Here, the strong/gusty surface winds, coupled with 20-25 percent minimum RH, should favor locally elevated conditions during the afternoon. Given below-normal precipitation during the last 15-30 days through this corridor (and at least modestly receptive fuels), Elevated highlights have been added. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No Mesoscale Discussions are in effect as of Tue Dec 20 18:15:02 UTC 2022.

No watches are valid as of Tue Dec 20 18:15:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1054 AM CST Tue Dec 20 2022 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast on Wednesday. ...Synopsis and Discussion... A weak mid-level disturbance will move from FL and coastal GA/SC into the western Atlantic Wednesday morning. Rich low-level moisture will remain confined along/south of a surface front that will be draped across the central/southern FL Peninsula. While isolated thunderstorms may occur across this region through the day, the lack of appreciable large-scale ascent aloft should limit overall convective coverage. A prominent upper trough is forecast to amplify further Wednesday across a broad part of the central CONUS as it translates eastward. A leading shortwave trough embedded within the larger upper trough should move quickly across the southern/central Plains to the Southeast and OH Valley through the period. Surface ridging centered over the East Coast will be slow to erode through Wednesday night. This should inhibit the return of appreciable low-level moisture inland across coastal SC. But, enough elevated instability may coincide with increasing forcing for ascent to support occasional thunderstorms late Wednesday night over parts of SC. ..Gleason.. 12/20/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1015 AM CST Tue Dec 20 2022 Valid 201630Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FL KEYS VICINITY... ...SUMMARY... While severe storms are unlikely, a severe wind gust is possible across the Florida Keys vicinity this evening. ...FL Keys... Scattered showers and isolated thunderstorms along a weak baroclinic/convergence zone over the western FL Straits, south and west of the Keys, should spread east-northeast into this evening towards the coastal waters adjacent to the southern tip of the peninsula. Farther west, an MCS across the east-central Gulf should persist east-southeast along the baroclinic zone, but weaken as it moves east of the Loop Current. The 12Z KEY sounding sampled weak, near-moist-adiabatic lapse rates that are not expected to steepen during the period, which will limit updraft strength. In addition, low-level winds should remain modest, yielding only minor enhancement to the low-level hodograph. The bulk of deep-layer shear contribution will be from strengthening winds above 700 mb. Overall setup suggests convection this evening will most likely remain sub-severe and weaken with approach to land over the Keys and adjacent portion of the southern Everglades. ..Grams/Moore.. 12/20/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0944 AM CST Tue Dec 20 2022 Valid 201700Z - 211200Z ...NO CRITICAL AREAS... The previous forecast (see below) remains on track. ..Squitieri.. 12/20/2022 .PREV DISCUSSION... /ISSUED 0154 AM CST Tue Dec 20 2022/ ...Synopsis... A continental polar airmass characterized by cold surface temperatures will encompass much of the western and central CONUS. As a result, fire-weather concerns will generally be minimal on Tuesday, despite locally dry/breezy conditions over parts of the central and southern High Plains. ...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 0134 PM CST Mon Dec 19 2022 Valid 192000Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms will continue to spread from eastern Texas across the Gulf Coast states. Though small hail is possible, severe weather remains unlikely over land. Surface observations along the Gulf Coast continue to show a rather stable air mass for surface-based parcels, with the best instability well offshore into the northwest Gulf of Mexico. Though a tight instability gradient will exist near the surface low, it is unlikely that this better air mass will reach shore. To the north, modest elevated instability and moderate deep-layer effective shear may support a few embedded storms capable of small hail through tonight, but hail over 1.00" diameter appears unlikely across Texas and Louisiana. ..Jewell.. 12/19/2022 .PREV DISCUSSION... /ISSUED 1015 AM CST Mon Dec 19 2022/ ...Synopsis... Mid-morning regional radar mosaics show a broad region of elevated convection across the TX coastal plain into central LA driven primarily by deep isentropic ascent in the 925-850 mb layer. Along the immediate TX Gulf Coast, surface observations suggest a small zone of warm/moist air (temperatures and dewpoint in the mid 60s) is in place that is supportive of surface-based convection. However, this air mass is expected to largely remain offshore over the next 24 hours as a weak surface low, currently off the Corpus Christi coast, translates east/northeast through the day. The broad zone of precipitation across east TX/LA will reinforce the coastal baroclinic zone, limiting the potential for surface-based buoyancy over land. Given somewhat strong speed shear in the 3-6 km layer, organized elevated convection is possible across portions of the TX coastal plain, mostly likely during the 17-20 UTC period when storm modes are most likely to be discrete before eventual upscale growth/increasing storm interactions within the warm advection regime. Small, sub-severe hail is possible with these storms, but the potential for 1+ inch hail appears sufficiently limited to withhold probabilities. Read more

No watches are valid as of Mon Dec 19 19:39:02 UTC 2022.

No Mesoscale Discussions are in effect as of Mon Dec 19 19:39:02 UTC 2022.

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1252 PM CST Mon Dec 19 2022 Valid 201200Z - 211200Z ...NO CRITICAL AREAS... Fire weather concerns remain minimal for Tuesday. Localized dry and windy conditions are possible in the immediate lee of the Rockies from northern NM through CO and into southern WY. However, the potential for elevated or critical wind/RH over receptive fuels remains low. ..Moore.. 12/19/2022 .PREV DISCUSSION... /ISSUED 0109 AM CST Mon Dec 19 2022/ ...Synopsis... Fire-weather concerns will be minimal on Tuesday, as cold surface temperatures accompanying a continental polar airmass infiltrate much of the western and central CONUS. ...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 1106 AM CST Mon Dec 19 2022 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms will be possible on Tuesday from the central Gulf Coast to Florida. No severe weather is expected. ...Synopsis... A shortwave trough will weaken as it moves east across the Gulf Coast, with a surface low over the northern Gulf of Mexico. Forecast soundings indicate only weak elevated instability over land, and a few thunderstorms may occur within the larger-scale area of precipitation from southeast Louisiana into Florida. Storms may approach the west Coast of Florida overnight, but the surface air mass will remain relatively cool, and severe storms are unlikely. ..Jewell.. 12/19/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1015 AM CST Mon Dec 19 2022 Valid 191630Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms should develop and spread eastward across the Gulf Coastal Plain from south Texas to near Mobile. Though small hail is possible, organized severe weather still appears unlikely over land. ...Synopsis... Mid-morning regional radar mosaics show a broad region of elevated convection across the TX coastal plain into central LA driven primarily by deep isentropic ascent in the 925-850 mb layer. Along the immediate TX Gulf Coast, surface observations suggest a small zone of warm/moist air (temperatures and dewpoint in the mid 60s) is in place that is supportive of surface-based convection. However, this air mass is expected to largely remain offshore over the next 24 hours as a weak surface low, currently off the Corpus Christi coast, translates east/northeast through the day. The broad zone of precipitation across east TX/LA will reinforce the coastal baroclinic zone, limiting the potential for surface-based buoyancy over land. Given somewhat strong speed shear in the 3-6 km layer, organized elevated convection is possible across portions of the TX coastal plain, mostly likely during the 17-20 UTC period when storm modes are most likely to be discrete before eventual upscale growth/increasing storm interactions within the warm advection regime. Small, sub-severe hail is possible with these storms, but the potential for 1+ inch hail appears sufficiently limited to withhold probabilities. ..Moore/Grams.. 12/19/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0958 AM CST Mon Dec 19 2022 Valid 191700Z - 201200Z ...NO CRITICAL AREAS... The previous forecast remains on track, with no changes or additions made. Please see the previous forecast below for more details. ..Squitieri.. 12/19/2022 .PREV DISCUSSION... /ISSUED 0108 AM CST Mon Dec 19 2022/ ...Synopsis... Broad/enhanced west-northwesterly flow aloft will encompass the western CONUS in the wake of a departing midlevel trough. In the low-levels, a remnant lee cyclone will meander southward and weaken over the southern High Plains. Along the southern periphery of the surface cyclone, breezy west-northwesterly surface winds and 15-20 percent RH are expected from the southern Rockies into the southern High Plains. While locally elevated conditions are possible here during the afternoon, cool surface temperatures and marginal fuels should generally limit the fire-weather threat. ...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 0127 PM CST Sun Dec 18 2022 Valid 182000Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated to scattered thunderstorms are expected overnight into early Monday morning across the Texas and Louisiana Gulf Coast. Little change was made to the previous outlook except to remove thunder chances from southern Florida given continued drying from the north. Otherwise, scattered elevated convection is expected overnight across parts of Texas as warm advection increases in advance of the shortwave trough. ..Jewell.. 12/18/2022 .PREV DISCUSSION... /ISSUED 1007 AM CST Sun Dec 18 2022/ ...Synopsis... Morning satellite imagery and surface observations show a cold front slowly pushing south across south FL. This boundary will continue to focus thunderstorm activity through the day amid modest buoyancy and minimal inhibition (as sampled by the 12 UTC KEY sounding). 30-40 knot mid-level winds may allow for transient storm organization, but multicellular storm mode and weak forcing for ascent will limit the severe threat. To the west, dry conditions are noted along the TX Gulf Coast with dewpoints in the low to mid 50s. Some degree of moistening of the continental air mass is apparent over the western Gulf in visible imagery, and additional moistening is expected as southerly low-level winds increase in response to an approaching shortwave trough (currently over southern AZ). The combination of low/mid-level moistening and increasing isentropic ascent will promote isolated to scattered shower/thunderstorm development after 03 UTC tonight. While most convection is expected to be elevated in nature, more robust surface-based thunderstorms are possible along the immediate TX coast where dewpoints in the low/mid 60s are probable and effective shear values could reach upwards of 40-50 knots. Ensemble guidance suggests this moisture will largely remain over coastal areas, limiting the potential for strong/severe storms over land. Read more

No watches are valid as of Sun Dec 18 19:32:02 UTC 2022.

No Mesoscale Discussions are in effect as of Sun Dec 18 19:32:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1107 AM CST Sun Dec 18 2022 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered storms will develop throughout the day on Monday over eastern Texas, and spread into Louisiana and southern Mississippi through Tuesday morning. Small hail may occur, but severe storms are not anticipated. ...Synopsis... A positive-tilt shortwave trough will move eastward across the southern Plains into the lower MS Valley, with a weak surface low developing over the northwest Gulf of Mexico. A surface high will remain over much of the East, and this will result in little to no surface moisture return. Increasing southerly winds above the surface will result in theta-e advection from TX into the lower MS Valley, with lift resulting in widespread precipitation. Elevated instability will favor scattered thunderstorms by midday over eastern TX, then into LA and southern MS overnight. Forecast soundings show maximum MUCAPE of 500-1000 J/kg may develop over eastern TX and LA, along with effective deep shear of 20-40 kt, depending on parcel levels. This may enhance effective-layer storm relative inflow, and possibly support small hail. A cool sub-cloud layer may also minimize melting, but at this time the overall severe threat appears low with numerous competing storms expected. ..Jewell.. 12/18/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1007 AM CST Sun Dec 18 2022 Valid 181630Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms will decrease in coverage across south Florida and the Keys through the afternoon. Isolated to scattered thunderstorms are expected overnight into early Monday morning across the Texas and Louisiana Gulf Coast. ...Synopsis... Morning satellite imagery and surface observations show a cold front slowly pushing south across south FL. This boundary will continue to focus thunderstorm activity through the day amid modest buoyancy and minimal inhibition (as sampled by the 12 UTC KEY sounding). 30-40 knot mid-level winds may allow for transient storm organization, but multicellular storm mode and weak forcing for ascent will limit the severe threat. To the west, dry conditions are noted along the TX Gulf Coast with dewpoints in the low to mid 50s. Some degree of moistening of the continental air mass is apparent over the western Gulf in visible imagery, and additional moistening is expected as southerly low-level winds increase in response to an approaching shortwave trough (currently over southern AZ). The combination of low/mid-level moistening and increasing isentropic ascent will promote isolated to scattered shower/thunderstorm development after 03 UTC tonight. While most convection is expected to be elevated in nature, more robust surface-based thunderstorms are possible along the immediate TX coast where dewpoints in the low/mid 60s are probable and effective shear values could reach upwards of 40-50 knots. Ensemble guidance suggests this moisture will largely remain over coastal areas, limiting the potential for strong/severe storms over land. ..Moore/Grams.. 12/18/2022 Read more