Severe Storms

MD 2062 CONCERNING SNOW SQUALL FOR EASTERN MISSOURI TO WESTERN ILLINOIS
Mesoscale Discussion 2062 NWS Storm Prediction Center Norman OK 1059 AM CST Thu Dec 22 2022 Areas affected...Eastern Missouri to western Illinois Concerning...Snow Squall Valid 221659Z - 222100Z SUMMARY...Sporadic, short-lived blizzard/snow squall conditions will be possible under a mesoscale snow band as it tracks east across parts of eastern Missouri and western Illinois through early/mid afternoon. DISCUSSION...Recent surface observations from far eastern IA show visibility reductions down to 1/4 mile at times under a persistent, though loosely organized, snow band. Based on latest RAP mesoanalysis, this band is primarily being driven by broad scale ascent ahead of a deepening upper low over the central Plains, augmented by more focused frontogenetical lift within the 850-700 mb layer. Forecast soundings indicate that much of this lift coincides with a 100-150 mb deep dendritic growth zone, which is likely yielding moderate, to at times heavy, snowfall rates up to 1 inch/hour. Concurrently, strong cold advection behind the surface front is supporting frequent wind gusts between 25-35 knots from eastern IA to central MO. The combination of these winds and moderate snowfall rates will likely result in periods of blizzard/snow squall conditions with visibility reductions briefly falling to 1/4 mile under the snow band as it continues moving east through early/mid afternoon. ..Moore.. 12/22/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LOT...ILX...LSX...DVN...SGF...EAX... LAT...LON 39969175 41699077 42249007 42128917 41658861 40958810 40208837 38978904 38298989 37559125 37559200 38439313 38789294 39259244 39969175 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1029 AM CST Thu Dec 22 2022 Valid 221630Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS WESTERN PART OF CENTRAL/SOUTH FL AND EASTERN NC... ...SUMMARY... A severe thunderstorm remains possible this afternoon across far eastern North Carolina. A few severe thunderstorms are possible this evening into tonight, mainly over western portions of central to south Florida. ...Central to south FL... Isolated to scattered thunderstorms are developing over the Loop Current in the east-central Gulf within a modest low-level warm advection regime. This regime will gradually shift east towards the west coast of FL through this evening and across the peninsula tonight. Typically, this setup would yield convection weakening as it approaches the relatively cooler waters along the west coast. But a strengthening mid-level jetlet, separate yet influenced by amplification of the longwave trough centered over the north-central states, could support offshore supercells reaching the coast. Low-level flow will modestly amplify, stronger north and weaker south, while gradually veering from southwest to west overnight. This could yield a marginal severe threat spreading somewhat inland before weakening towards dawn. ...Eastern NC... A 1011-mb surface low near the NC/SC coastal border should deepen somewhat as it tracks northeast over eastern NC this afternoon. The corridor of surface-based instability near this cyclone will remain quite narrow inland of the shelf waters as abundant elevated showers and thunderstorms persist in the warm conveyor downstream. This process will likely mitigate diabatic destabilization until after convection passes by, but mid-level subsidence will ensue with substantial drying and weak warming aloft. This setup suggests that the environment conditionally favorable for surface-based supercells may remain storm-free, which is largely supported by morning CAM guidance. The southern Outer Banks should have the relatively greatest potential for a supercell to brush the region during the afternoon, with a brief severe wind gust or weak tornado possible. ..Grams/Moore.. 12/22/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1028 AM CST Thu Dec 22 2022 Valid 221700Z - 231200Z ...NO CRITICAL AREAS... Winds of 15-20 mph and relative humidity around 20-25 percent is currently being observed locally across portions of southwest Texas. However, these conditions will be brief as an arctic cold front continues to move southwestward into the area. In addition, fuels are mostly moist across this region which also precludes significant fire weather concern. ..Bentley.. 12/22/2022 .PREV DISCUSSION... /ISSUED 0144 AM CST Thu Dec 22 2022/ ...Synopsis... Anomalously cold surface temperatures accompanying an arctic airmass across the central CONUS will generally limit fire-weather concerns on Thursday. The one exception will be over parts of southwest TX, where a brief period of dry/breezy conditions is possible ahead of a southward-advancing cold front. However, these conditions should be too marginal/brief for any appreciable fire-weather threat. ...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 0133 PM CST Wed Dec 21 2022 Valid 221200Z - 231200Z ...NO CRITICAL AREAS... The previous forecast (see below) remains on track. ..Squitieri.. 12/21/2022 .PREV DISCUSSION... /ISSUED 0142 AM CST Wed Dec 21 2022/ ...Synopsis... An arctic airmass will infiltrate much of the central CONUS along/east of the Rockies, generally limiting fire-weather concerns on Thursday. While a brief period of dry/breezy conditions is possible over southwest TX ahead of the southward-advancing cold front, these conditions should be too brief/marginal for any appreciable fire-weather threat. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Wed Dec 21 19:35:02 UTC 2022.

MD 2055 CONCERNING SNOW SQUALL FOR WYOMING TO SOUTHWEST SOUTH DAKOTA AND NORTHWEST NEBRASKA
Mesoscale Discussion 2055 NWS Storm Prediction Center Norman OK 1205 PM CST Wed Dec 21 2022 Areas affected...Wyoming to southwest South Dakota and northwest Nebraska Concerning...Snow Squall Valid 211805Z - 212100Z SUMMARY...Snow squalls will remain possible across northern and central Wyoming into portions southwest South Dakota and northwest Nebraska through the mid-afternoon hours as an arctic front continues to push south. DISCUSSION...Latest surface observations continue to show reduced visibility at or below one-quarter mile across much of central and northern WY where post-frontal winds are gusting to 45 mph amid light to moderate snow showers. Across western SD, snow has begun to increase in coverage as lift along the frontal surface increases. The combination of light falling snow, sustained winds near 20 mph (gusting to 30-40 mph), and a pre-existing snow pack are resulting in sporadic visibility reductions - particularly in open country. The expectation through mid-afternoon is for a continuation of persistent snow squalls across central WY where stronger winds and heavier snow rates (bolstered by embedded convective elements) will yield visibility reductions near/below one-quarter mile. Across SD/WY, more localized/sporadic post-frontal snow squalls are expected as strong cold advection continues over the next few hours and supports deeper downward mixing of 30-45 mph winds. Impacts will be most notable across open country where blowing snow model output suggests visibility reductions to one-quarter mile will become more likely as sustained wind speeds reach the 25-30 mph range. ..Moore.. 12/21/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ABR...LBF...UNR...CYS...BYZ...RIW... LAT...LON 42570014 42210042 41980121 41790214 41620336 41630436 41770582 42090734 42500850 42850944 43181000 43511003 44210994 44690945 44780465 45280259 45040175 44410097 42570014 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CST Wed Dec 21 2022 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EASTERN NORTH CAROLINA...SOUTHEASTERN VIRGINIA...AND PORTIONS OF THE FLORIDA PENINSULA... ...SUMMARY... Isolated strong to severe thunderstorms may occur Thursday over eastern North Carolina and southeastern Virginia, as well as parts of the Florida Peninsula. ...Eastern North Carolina and Southeastern Virginia... A pronounced upper trough will continue eastward Thursday across the central/eastern CONUS. A strong cold front will sweep east- southeastward over these regions in tandem with the upper trough. A secondary surface low over coastal SC Thursday morning is forecast to develop northeastward across central/eastern NC and southeastern VA through the day. The inland return of low-level moisture across coastal/eastern NC should be limited owing to residual surface ridging over the Mid-Atlantic/Northeast that should be slow to erode. Still, it appears that upper 50s to low 60s surface dewpoints should be present in a narrow corridor over eastern NC and far southeastern VA as the surface low develops northeastward. Poor lapse rates and only modest daytime heating will likely keep instability weak, even though low-level and deep-layer shear are forecast to be quite strong. Given the strength of the low-level flow, isolated strong/damaging winds may occur with low-topped convection spreading quickly northeastward through the morning and afternoon. Better tornado potential should remain offshore where greater low-level moisture is present, but a brief tornado appears possible along the immediate NC Coast and Outer Banks. ...Florida Peninsula... Rich low-level moisture will likely remain confined along/south of a residual front across the FL Peninsula on Thursday. This region will remain mostly displaced to the south of ascent associated with the upper trough over the central/eastern CONUS. However, a strong west-southwesterly mid-level jet will spread over much of FL through the day. Low-level convergence along the surface boundary should remain weak. But, any convection that can develop along/south of this boundary could become organized in the presence of weak instability and strong deep-layer shear. Isolated damaging winds appear to be the main threat if any thunderstorm can be sustained. ..Gleason.. 12/21/2022 Read more

MD 2054 CONCERNING HEAVY SNOW FOR SOUTHEAST SOUTH DAKOTA...FAR NORTHWEST IOWA...SOUTHERN MINNESOTA INTO FAR NORTHWEST WISCONSIN
Mesoscale Discussion 2054 NWS Storm Prediction Center Norman OK 1033 AM CST Wed Dec 21 2022 Areas affected...Southeast South Dakota...far northwest Iowa...southern Minnesota into far northwest Wisconsin Concerning...Heavy snow Valid 211633Z - 212030Z SUMMARY...The potential for heavy snowfall rates between 1-2 inches per hour is expected to increase through the late morning and early afternoon from the mid Missouri River Valley to the upper Mississippi River Valley. DISCUSSION...Regional radar mosaics from the past 1-3 hours show an elongated zone of increasing reflectivity values from eastern SD to southern MN. This is likely in response to strengthening isentropic ascent in the 925-700 mb layer within a broad warm frontal zone draped across the region. This mesoscale ascent is augmenting more broad, synoptic lift ahead of an approaching shortwave trough over the northern Plains, and is supporting an increase in coverage of moderate, to at times heavy, snowfall rates per latest surface observations and regional web cams. Latest guidance suggests that this trend should continue through at least early afternoon as the synoptic low continues east/southeast and saturation of the lowest 1-2 km continues. Forecast soundings indicate that much of the low/mid-level ascent coincides with a ~100 mb deep dendritic growth zone, which will favor efficient snow production and the potential for heavy snowfall rates around 1 inch per hour. The current warm advection regime over eastern SD/southern MN will likely support periods of broken snow bands through the early afternoon (which appears probable based on latest reflectivity trends), and this may yield localized higher snowfall rates between 1-2 inches/hour. The approach of the mid-level cold front later this afternoon may maintain the potential for localized banding via frontogenetical processes. ..Moore.. 12/21/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DLH...ARX...MPX...DMX...FSD...ABR... LAT...LON 45649472 45919387 45959300 45809240 45299199 44759199 44179265 43729372 43059523 42879587 42899669 43129722 43519746 44169712 44959611 45649472 Read more

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