Severe Storms

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1117 AM CST Wed Feb 22 2023 Valid 231200Z - 241200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few lightning flashes will be possible from southwest Oregon across the California Coast and into northwest Arizona throughout the period. Isolated thunderstorms are also possible across portions of the Southeast later Thursday evening. ...Synopsis... A belt of strong southwesterly flow aloft is expected to extend across the CONUS, from southern CA northeastward through the central Plains and into the Upper Great Lakes/Northeast, early Thursday morning. A shortwave trough embedded within this southwesterly flow is forecast to move from the mid MO Valley quickly northeastward through the Upper Midwest and Great Lakes throughout the day. An associated surface low will take a similar path, moving from central IL northeastward through the Northeast as an attendant cold front sweeps southeastward. By 12Z Friday, this low will likely be centered off the ME coast, with the cold front extending back southwestward from this low through NC, central portions of the Southeast states, and into southeast TX. Farther west, an upper low will continue southward along the West Coast, from just off the Pacific Northwest coast early Thursday to off the northern CA Coast by early Friday. At the same time, a shortwave trough is expected to proceed this low, moving from southern CA to the Four Corners. ...Northeast... Shallow convection is possible from northern PA through central NY/Hudson Valley and into southern New England Thursday evening amid strengthening warm-air advection and modest ascent attendant to the approaching surface low. A warm front will likely remain in place across southern NY into southern New England, with the surface low moving along this front. Consequently, most of this convection will be elevated. Additionally, warm mid-level temperatures will keep an updrafts shallow, likely limiting lightning production. Even so, given the strong low to mid-level flow, a few stronger gusts are possible with this convection. ...Southeast... Frontal progression will likely slow Thursday evening at it reaches northern MS/AL, in response to gradually strengthening low-level southerly flow. Resulting increasing in warm-air advection may trigger a few thunderstorms within the modestly moist air mass in place from the Mid-South into northern MS/AL. ...West Coast into Northwest AZ... Strong ascent and cold mid-level temperatures associated with the upper low will contribute to isolated thunderstorms throughout the period from coastal OR along the CA coast into southern CA. Isolated thunderstorms are also possible ahead of the lead shortwave trough across northwestern AZ vicinity Thursday evening. ..Mosier.. 02/22/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1033 AM CST Wed Feb 22 2023 Valid 221630Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE OZARKS/MIDDLE MISSISSIPPI VALLEY... ...SUMMARY... Scattered damaging winds are possible from the Ozarks to the Mid-Mississippi and Lower Ohio Valleys through the afternoon. ...Ozarks/Mid-South and Lower/Middle Mississippi Valley... A compact shortwave trough and related speed max centered over eastern portions of Kansas/Oklahoma/Texas will continue to quickly race northeastward through tonight. Related wind fields will remain very strong, although the aforementioned system will gradually minor by late today while mid-level temperatures warm to its south. Initially, to the north of a warm front, ongoing elevated storms across east-central Illinois/west-central Indiana could pose an isolated/marginal severe hail risk through early afternoon. Farther southwest, within the warm sector, a very low-topped semi-organized semi-broken/wavy convective line extends from south-central/southwest Missouri south-southwestward into western Arkansas and the ArkLaTex vicinity, with little if any lightning flashes as of late morning. Line-preceding cloud breaks are noted across central/eastern Arkansas into far southeast Missouri, generally coincident with surface temperatures that have already reached 70F and surface dewpoints in the lower 60s F. Given this scenario, a modest diurnal heating-related uptick in updraft/downdraft intensity is plausible, although the weak overall buoyancy should limit the overall magnitude of the severe risk. Regardless, some potential for locally damaging winds and possibly a couple of brief tornadoes will exist especially across northern Arkansas/southern Missouri into southern/south-central Illinois. For additional short-term information, see Mesoscale Discussion 175. Farther southeast, a somewhat separate pre-frontal regime, for a least a low/conditional-type surface-based risk, will exist in closer proximity to the Mississippi River through late afternoon and possibly early evening. ..Guyer/Supinie.. 02/22/2023 Read more

No watches are valid as of Tue Feb 21 20:16:01 UTC 2023.

No Mesoscale Discussions are in effect as of Tue Feb 21 20:16:01 UTC 2023.

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0151 PM CST Tue Feb 21 2023 Valid 221200Z - 231200Z ...Southern Plains... Broad elevated fire-weather conditions remain possible Wednesday across portions of the Southern Plains and west Texas. An early morning round of precipitation is likely over portions of western OK and North Texas which will likely temper already marginal fuels. The Elevated area has been adjusted westward. Farther south and west, low-level winds are likely to remain strong after the passage of a dryline/Pacific front. The greatest confidence in sustained fire-weather conditions remains across portions of West Texas, the Big Bend and southern portions of the Texas Panhandle. Though fuels here are also only marginally receptive to large fire spread lending low confidence. Thus, a Critical area will not be added to the outlook area given concerns about afternoon RH and fuels. Elevated to locally critical fire-weather conditions remain possible given very strong surface winds gusting over 35 mph. Please see the previous discussion for additional information. ..Lyons.. 02/21/2023 .PREV DISCUSSION... /ISSUED 0152 AM CST Tue Feb 21 2023/ ...Synopsis... A potent shortwave trough will be exiting the southern High Plains while another larger-scale trough moves into Great Basin and Southwest on Wednesday. A strong mid-level jet will overspread the Texas Panhandle vicinity by late afternoon. At the surface, an initial cold front will depart the region early in the day. With deepening of the trough to the west, another surface low will develop within the combined Panhandles by late afternoon. A secondary Pacific cold front is expected to move into the southern High Plains as that occurs. ...Southern Plains... Another day of broad elevated to locally critical fire weather is expected. While the upper and lower level wind fields will be favorable for critical fire weather, the low-level thermal fields do not appear to be well-aligned with the winds. The axis of warmer temperatures will be displaced to the east of the strongest winds. Furthermore, the arrival of the Pacific front may also limit the degree to which RH will fall in the afternoon. Models, including the typically aggressively dry HRRR/RAP, are fairly adamant that RH of around 25% will be common in the South Plains into the Texas Panhandle and western Oklahoma with local values near 20% possible. Farther south into the Trans-Pecos and Big Bend, RH could fall near or below 15%. However, fuels are less receptive, some precipitation is possible Tuesday night, and winds may only exceed 20 mph locally. The area with the most potential for larger fires will be from the northern South Plains into the Panhandles and perhaps western Oklahoma. Winds of 20-35 mph are possible in these areas and fuels will be drier than farther south. Should confidence in RH being lower or fuels being drier increase, critical highlights may be needed. ...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 0144 PM CST Tue Feb 21 2023 Valid 212000Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF THE MID-ATLANTIC AND THE SOUTHERN PLAINS... ...SUMMARY... Isolated thunderstorms capable of locally damaging winds will be possible across parts of the Mid-Atlantic through late afternoon. Isolated severe wind and hail will be possible after 2 AM CST across a portion of western north Texas into central Oklahoma. ...20z Update... Isolated thunderstorms have developed across portions of the mid-Atlantic and northeast U.S. in advance of a cold front and in association with a mid-level shortwave trough. For additional details on short-term trends please refer to MCD 171 issued at 1901z. Otherwise, an eastward adjustment to the western edge of the 10 percent thunderstorm line was made based on current observations/trends. The previous outlook reasoning and risk area remains on track regarding development of thunderstorms late tonight over the southern Plains and the associated severe potential. ..Bunting.. 02/21/2023 .PREV DISCUSSION... /ISSUED 0127 PM CST Tue Feb 21 2023/ ...Mid-Atlantic States... A low-amplitude shortwave trough over southern Ontario and the Lower Great Lakes will continue east-northeastward toward New England tonight. Boundary layer moisture will remain limited within the post-coastal frontal environment, but cloud breaks/moderate heating and 40s F surface dewpoints will lead to weak destabilization early this afternoon. This could allow for the development of some low-topped thunderstorms (less than 25k ft) across eastern Pennsylvania to New Jersey and the Delmarva vicinity. A few storms could produce small hail this afternoon along with strong/convectively enhanced wind gusts, particularly given the strength of the background west-southwesterly low/mid-tropospheric winds. ...Southern Great Plains... Influenced by a southern-stream low-latitude trough that will reach eastern New Mexico/far west Texas tonight, late-day lee cyclogenesis and a strengthening of southerly low-level winds will influence additional moistening across the region. Initially modest moisture and residual capping will likely preclude thunderstorm development until later tonight. A narrow corridor of meager boundary-layer destabilization with MLCAPE of 250-500 J/kg is anticipated to evolve late tonight and early Wednesday ahead of a sharpening cold front ejecting eastward from the High Plains. Strengthening forcing for ascent downstream of an elongated shortwave trough over the southern High Plains will support increasing convective development, especially in the 09-12Z time frame. A few instances of severe hail and/or wind may occur across southwest/central Oklahoma and western North Texas. ...East-central Illinois to southwest Ohio... Elevated convection is expected to develop late tonight/early Wednesday amid strengthening lower-level warm theta-e advection. Most of this activity should occur within scant elevated buoyancy, but strong speed shear through the cloud-bearing layer may support small hail in the more robust updrafts. Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook RESENT 2 NWS Storm Prediction Center Norman OK 0130 PM CST Tue Feb 21 2023 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL AND EASTERN OKLAHOMA NORTHEAST INTO WEST-CENTRAL ILLINOIS... ...SUMMARY... Severe thunderstorms are possible from Wednesday morning through afternoon from parts of Oklahoma into western Arkansas, across Missouri and western Illinois. Damaging winds appear most likely. ...Synopsis... Within a large-scale mid/upper-level trough, a pronounced shortwave trough will lift rapidly northeast from the southern Plains towards the Great Lakes. Intense low/mid-level wind fields will accompany this shortwave trough as it accelerates northeast and generally weakens while moving into a more confluent mid-level flow regime. Farther west, a strong upper-level speed max will drop south along the west coast and contribute to the development of a closed upper low near the CA coast. Surface low pressure will develop along a front over eastern KS and move towards northern IL late Wednesday. ...OK northeast into MO/IL/IN and northwest AR... Strong/severe thunderstorms may be ongoing across central/eastern OK at 12z Wednesday in the vicinity of the dryline/cold front. The presence of surface dew points in the upper 50s/lower 60s will contribute to modest instability ranging from 250 to 750 J/kg across the warm sector during the day, and storms are expected to move rapidly northeast during the morning and afternoon. Very strong low- and mid-level wind fields (50-65 kts) will translate northeast with the shortwave trough and provide a favorable environment for strong/severe wind gusts with the stronger convective elements. Although large-scale ascent will tend to weaken with time as the trough moves into increasingly confluent mid-level flow over the Great Lakes, at least some severe risk may persist as far east as central IL and western IN. Low severe wind probabilities have been extended east accordingly. Although the predominant linear mode will result in damaging winds as the main severe risk, a brief tornado cannot be ruled out given favorable low-level shear and at least some potential for transient supercell structures and QLCS circulations. ..Bunting.. 02/21/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook RESENT 1 NWS Storm Prediction Center Norman OK 0127 PM CST Tue Feb 21 2023 Valid 211630Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE MID-ATLANTIC AND SOUTHERN PLAINS... ...SUMMARY... Isolated thunderstorms capable of locally damaging winds will be possible across parts of the Mid-Atlantic from about Noon to 4 PM EST. Isolated severe wind and hail will be possible after 2 AM CST across a portion of western north Texas into central Oklahoma. ...Mid-Atlantic States... A low-amplitude shortwave trough over southern Ontario and the Lower Great Lakes will continue east-northeastward toward New England tonight. Boundary layer moisture will remain limited within the post-coastal frontal environment, but cloud breaks/moderate heating and 40s F surface dewpoints will lead to weak destabilization early this afternoon. This could allow for the development of some low-topped thunderstorms (less than 25k ft) across eastern Pennsylvania to New Jersey and the Delmarva vicinity. A few storms could produce small hail this afternoon along with strong/convectively enhanced wind gusts, particularly given the strength of the background west-southwesterly low/mid-tropospheric winds. ...Southern Great Plains... Influenced by a southern-stream low-latitude trough that will reach eastern New Mexico/far west Texas tonight, late-day lee cyclogenesis and a strengthening of southerly low-level winds will influence additional moistening across the region. Initially modest moisture and residual capping will likely preclude thunderstorm development until later tonight. A narrow corridor of meager boundary-layer destabilization with MLCAPE of 250-500 J/kg is anticipated to evolve late tonight and early Wednesday ahead of a sharpening cold front ejecting eastward from the High Plains. Strengthening forcing for ascent downstream of an elongated shortwave trough over the southern High Plains will support increasing convective development, especially in the 09-12Z time frame. A few instances of severe hail and/or wind may occur across southwest/central Oklahoma and western North Texas. ...East-central Illinois to southwest Ohio... Elevated convection is expected to develop late tonight/early Wednesday amid strengthening lower-level warm theta-e advection. Most of this activity should occur within scant elevated buoyancy, but strong speed shear through the cloud-bearing layer may support small hail in the more robust updrafts. ..Guyer/Supinie.. 02/21/2023 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0120 PM CST Tue Feb 21 2023 Valid 211700Z - 221200Z ...Southern High Plains... Overall, the forecast is on track and largely unchanged. Considerable uncertainty remains with respect to area RH values this afternoon and evening. Mid and high cloud cover will likely reduce heating through the afternoon hours with only spotty coverage of RH below 20% likely over portions of the OK Panhandle. However, strong southwesterly winds will be likely over much of the southern High Plains this afternoon. While fuels and RH values will limit higher end fire-weather potential, strong winds and pockets of dry fine fuels should support a few hours of elevated to locally critical fire-weather concerns. ..Lyons.. 02/21/2023 .PREV DISCUSSION... /ISSUED 1245 AM CST Tue Feb 21 2023/ ...Synopsis... An upper-level trough near Baja will eject into the southern High Plains by late tonight. At the surface, a low will deepen in the southern/central High Plains vicinity. Strong surface winds are expected to develop in association with the surface low across the region. ...Southern High Plains... Surface winds are expected to increase to 20-30 mph over a broad area as the surface pressure gradient strengthens. RH will continue to be a major source of uncertainty. With the approach of the trough from the west, high/mid-level clouds are expected to increase across the Southwest into Texas and Oklahoma. Along the northern fringe of the cloud deck, additional heating may allow RH to fall as low as 15% in parts of the Panhandles into southeast Colorado and southwest Kansas. Farther south and east, RH of 20-25% becomes much more likely. Another factor mitigating the impacts of the strong winds will be the modestly receptive fuels. Critical conditions will most likely occur in the vicinity of the Oklahoma Panhandle. Aside from the lack of critically dry fuels, critical conditions may also be relatively brief in any one location as the cloud deck will likely shift north during the day. ...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 0150 PM CST Mon Feb 20 2023 Valid 202000Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...Discussion... Aside from minor areal adjustments, no changes are required to the ongoing forecast. Severe storms are not expected. ..Goss.. 02/20/2023 .PREV DISCUSSION... /ISSUED 1022 AM CST Mon Feb 20 2023/ ...Tennessee Valley/Lower Mississippi Valley... A low-amplitude upper flow regime will persist over the CONUS including split flow over the West. Low-level moistening will occur through tonight to the south of a front across the Ozarks and lower/middle Ohio River Valley. A modest increase in forcing for ascent and weak elevated buoyancy should yield some elevated thunderstorms after sunset, especially late this evening into the overnight from the Lower Mississippi Valley to the Tennessee Valley. Read more

No watches are valid as of Mon Feb 20 19:54:02 UTC 2023.

No Mesoscale Discussions are in effect as of Mon Feb 20 19:54:02 UTC 2023.

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0143 PM CST Mon Feb 20 2023 Valid 211200Z - 221200Z The forecast remains on track with only minor adjustments needed. The primary change was to expand the elevated risk area further northward into southwest KS where dry southerly flow on the eastern periphery of the surface low should result in 15-25 mph winds coincident with RH values near 20%. A broad region of elevated conditions is expected, and critical wind/RH conditions are most likely across the northern TX Panhandle into the OK Panhandle. However, fuel status remains questionable across much of the region per latest fuel analyses and guidance. See the previous discussion below for additional details. ..Moore.. 02/20/2023 .PREV DISCUSSION... /ISSUED 0100 AM CST Mon Feb 20 2023/ ...Synopsis... The cut-off low near Baja will continue eastward, become more of an open wave as it moves through the Southwest. Moderate to strong mid-level flow will be situated within the southern Rockies. More significant deepening of a High Plains low is expected on Monday. Low-level winds will increase as a result across parts of the southern and central Plains areas. Winds of 15-30 mph appear possible from West Texas into western Oklahoma, southwestern Kansas, and near the terrain in southeast Colorado. Fuels have continued to dry under the influence of previous days of dry/breezy conditions. Still, some impact will remain from recent snowfall, particularly for areas farther north/west and the driest fuels will not be significantly below average for this time of year. Despite some spread in model guidance, it does seem reasonable to expect RH to fall to around 15 to 20% in some areas. Broad elevated to locally critical conditions are expected given the strong winds and low RH. As mentioned, a lack of more receptive fuels will limit the overall threat for ignitions/spread. ...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 1129 AM CST Mon Feb 20 2023 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected across the U.S. on Tuesday. ...Discussion... Amplification of the upper flow field is expected across the U.S. Tuesday. This will occur as a low initially off the Baja coast is kicked eastward across northern Mexico toward the southern Plains, by an evolving trough now over the Gulf of Alaska that is expected to amplify and dig rapidly southward along the western NOAM coast. As this progression proceeds, and a large area of cyclonic flow evolves across the western half of the country, downstream ridging will amplify across the eastern states through latter stages of the period. Limited instability across the country will preclude any appreciable severe potential. Southerly flow evolving from the southern Plains and eventually into the Mid and Lower Mississippi/Tennessee/Ohio Valleys will advect higher theta-e air northward atop a stable boundary layer, resulting in widespread precipitation and embedded lightning across this area. Farther west, widespread showers are expected as troughing evolves, with some lightning possible in a few areas including portions of the West Coast, Great Basin, and Desert Southwest. ..Goss.. 02/20/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1022 AM CST Mon Feb 20 2023 Valid 201630Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...Tennessee Valley/Lower Mississippi Valley... A low-amplitude upper flow regime will persist over the CONUS including split flow over the West. Low-level moistening will occur through tonight to the south of a front across the Ozarks and lower/middle Ohio River Valley. A modest increase in forcing for ascent and weak elevated buoyancy should yield some elevated thunderstorms after sunset, especially late this evening into the overnight from the Lower Mississippi Valley to the Tennessee Valley. ..Guyer/Weinman.. 02/20/2023 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1019 AM CST Mon Feb 20 2023 Valid 201200Z - 211200Z ...NO CRITICAL AREAS... ...Synopsis... A cut-off low aloft will continue to make very slow progress eastward toward the Baja Peninsula today. Moderate zonal flow across the southern Rockies will continue. A cold front from the Texas Panhandle into Oklahoma will stall. With some pressure gradient enhancement near the boundary, westerly winds across parts of the Texas Panhandle and South Plains could reach 15-25 mph. Fuels have been able to dry as conditions have been modestly dry and breezy recently. However, RH below critical thresholds remains questionable given high/mid-level clouds. Values near the boundary will likely fall to around 20% with some locally lower values. Farther south, RH will be higher. Locally elevated fire weather is possible in the Texas Panhandle into perhaps western Oklahoma. ..Wendt.. 02/20/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Sun Feb 19 20:46:02 UTC 2023.

No Mesoscale Discussions are in effect as of Sun Feb 19 20:46:02 UTC 2023.

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0153 PM CST Sun Feb 19 2023 Valid 192000Z - 201200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are not expected through tonight. ...Synopsis... No thunderstorms expected. ..Goss.. 02/19/2023 .PREV DISCUSSION... /ISSUED 1018 AM CST Sun Feb 19 2023/ ...Discussion... Conditions will remain unfavorable for thunderstorms. A few showers may develop across south Florida and/or near the Atlantic coast later today, but deeper convection capable of lightning is unlikely. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0140 PM CST Sun Feb 19 2023 Valid 201200Z - 211200Z ...NO CRITICAL AREAS... The previous forecast remains on track. Latest guidance continues to show slight displacement of the driest conditions (across southeast CO and southwest KS), and the strongest winds (across west TX and portions of the TX Panhandle and western OK). Localized elevated conditions remain possible over parts of the TX Panhandle, but confidence in the spatial extent of the threat, as well as fuel status across the region, remains limited. See the previous discussion for further details. ..Moore.. 02/19/2023 .PREV DISCUSSION... /ISSUED 1242 AM CST Sun Feb 19 2023/ ...Synopsis... For Monday, moderately strong mid-level winds will continue across the southern Rockies as the cut-off low over Baja becomes more of an open wave moving east. The sagging cold front in the southern Plains will stall within the Texas Panhandle and Oklahoma. Another lee low will eventually develop during the afternoon in southeast Colorado. The overall setup will be similar to what occurs on Sunday, though slightly shifted to the south. Surface winds of 15 to perhaps 25 mph in some locations will be possible in parts of eastern New Mexico into the Texas Panhandle and South Plains. However, RH will once again be a major question. High and mid-level clouds are expected especially with southward extent. Afternoon RH of 20-25% is expected to be relatively common. There again may exist a small corridor in the central/northern Panhandle vicinity that will be on the edge of the greater cloud cover. RH near 15% is possible within that zone. As with Sunday, locally elevated fire weather concerns are expected. ...Please see www.spc.noaa.gov/fire for graphic product... Read more