Severe Storms

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1250 PM CST Sun Jan 01 2023 Valid 021200Z - 031200Z The forecast remains on track with only minor adjustments need to the Elevated risk area based on trends in latest guidance. Areas of elevated fire weather conditions remain likely across portions of west TX and the TX Panhandle Monday afternoon. Drier/windier solutions hint at the potential for elevated conditions as far north as the OK Panhandle and across the Big Bend region of southwest TX. However, confidence in this scenario is too low to warrant an expansion given poor model/ensemble consensus. See the previous discussion for further details. ..Moore.. 01/01/2023 .PREV DISCUSSION... /ISSUED 1257 AM CST Sun Jan 01 2023/ ...Synopsis... A strong mid-level jet will eject into the southern High Plains on Monday. A surface low will develop in the vicinity of western Kansas into perhaps the northern Texas Panhandle and western Oklahoma. Confidence in surface winds of 15-25 mph is medium to high, particularly for areas beneath the mid-level jet in the Texas South Plains and portions of the Permian Basin. Westerly winds behind a surface trough should promote some amount of low-level drying. However, guidance is not certain RH below 20% will be widespread. With that said, some pockets of low-end elevated conditions appear possible in the Texas Panhandle into the northern Permian Basin. Given some recent fire activity in the region, highlights were kept on account of the stronger winds and areas of fine fuels capable of carrying fire. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Sun Jan 1 18:52:01 UTC 2023.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CST Sun Jan 01 2023 Valid 021200Z - 031200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EAST TEXAS...SOUTHEASTERN OKLAHOMA...ARKANSAS...AND NORTHERN LOUISIANA... ...SUMMARY... Severe thunderstorms are expected Monday and Monday night from eastern Oklahoma and Texas into Louisiana/Arkansas and vicinity. Tornadoes and scattered damaging winds will be the main hazards with these storms. Some of the tornadoes could be strong. ...Eastern Oklahoma/Texas into the Lower Mississippi Valley... A potent upper trough will pivot from the Southwest/Four Corners region across the southern/central Rockies and Plains on Monday, while acquiring a negative tilt as it ejects over the Plains Monday night. This trough will be accompanied by enhanced low/mid-level winds overspreading much of the southern/central Plains into the lower MS Valley and Mid-South through the period. Strong low-level southerly winds associated with a 40-50+ kt low-level jet will advect Gulf moisture northward across east TX/OK into the lower/mid MS Valley, with mid to upper 60s surface dewpoints becoming common from east TX into southeastern OK, LA, and AR by Monday evening. A surface low is forecast to consolidate over the southern/central High Plains as pronounced large-scale ascent preceding the upper trough overspreads this region. This surface low should develop quickly northeastward across OK/KS and into northern MO/IA through Monday night. An attendant cold front will sweep quickly eastward over the southern Plains and towards the lower/mid MS Valley through the period. Fairly widespread cloud cover will probably tend to hinder robust daytime heating across much of the warm sector. Even with this potential limitation, cooling mid-level temperatures and steepening lapse rates aloft should help compensate to some extent. Most guidance suggests that sufficient instability will develop east of the cold front by Monday afternoon, with MLCAPE around 1000-1500 J/kg possible where at least mid 60s surface dewpoints are in place. Weaker boundary-layer instability should exist farther north into eastern KS and MO, with a more isolated/marginal severe threat possible. Most high-resolution guidance indicates that scattered convection will develop within the strong low-level warm advection regime around midday across the ArkLaTex vicinity as the cap erodes, and subsequently spread northeastward into a somewhat less favorable thermodynamic environment. These thunderstorms may pose a threat for all severe hazards initially, before becoming mainly elevated. The prospect for additional robust convective development in the open warm sector ahead of the front Monday afternoon/evening remains uncertain. A southerly low-level jet is expected to continue strengthening through the day from the ArkLaTex into the lower MS Valley in tandem with the approaching upper trough. Enhanced deep-layer flow and 40-50+ kt of effective bulk shear will easily support supercell structures. The primary uncertainty is how many supercells will actually develop before convection grows upscale along the front Monday evening/night. Even with this uncertainty, the potential for tornadoes remains apparent, as low-level shear will be more than adequate for updraft rotation. If a supercell can be maintained, then a strong tornado also appears possible. Otherwise, isolated large hail may occur with initially semi-discrete convection. A transition to more of a damaging wind threat appears probable as thunderstorms gradually congeal into one or more bowing line segments along or just ahead of the front Monday night. But, a threat for tornadoes embedded within the line will likely continue across the lower MS Valley through early Tuesday morning. ..Gleason.. 01/01/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1026 AM CST Sun Jan 01 2023 Valid 011630Z - 021200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF CENTRAL/SOUTHERN ARIZONA... ...SUMMARY... Isolated strong-severe thunderstorm gusts are possible today over parts of central/southern Arizona. ...Central/Southern Arizona... A deep, highly amplified large-scale trough (characterized by 500-mb temperatures near -26C) will track eastward from south-central CA across AZ through the period. Preceding the midlevel trough, strong deep-layer southwesterly flow and substantial midlevel height falls will overspread AZ this afternoon, while a Pacific cold front sweeps eastward from the Lower CO River Valley across AZ. Widespread cloud coverage and a band of stratiform rain (with embedded convective elements) are ongoing across south-central AZ ahead of the eastward-advancing cold front, which will generally limit pre-frontal diurnal heating/destabilization this afternoon. Nevertheless, as the very cold midlevel temperatures/steep midlevel lapse rates and strong DCVA (accompanying the large-scale trough) overspread lower/middle 50s boundary-layer dewpoints, marginal instability (200-500 J/kg MLCAPE) will support a line of strongly forced, surface-based convection along/immediately ahead of the cold front. While the limited instability could limit updraft intensity, 30-40 kt of effective shear oriented oblique to the cold front should favor a loosely organized line of storms capable of locally damaging gusts across south/central AZ this afternoon -- especially given the strong background deep-layer wind field and large-scale ascent. ..Weinman/Hart.. 01/01/2023 Read more

MD 0001 CONCERNING HEAVY SNOW FOR HIGHER TERRAIN AREAS OF THE MOGOLLON RIM IN CENTRAL INTO EAST-CENTRAL ARIZONA
Mesoscale Discussion 0001 NWS Storm Prediction Center Norman OK 1007 AM CST Sun Jan 01 2023 Areas affected...higher terrain areas of the Mogollon Rim in central into east-central Arizona Concerning...Heavy snow Valid 011607Z - 012200Z SUMMARY...Heavy snow is expected across the higher terrain areas of the Mogollon Rim through the afternoon, especially above 6000 ft. 2-3 inch/hr rates are possible and brief bouts of locally heavier rates cannot be ruled out. DISCUSSION...A coupled upper trough and surface-850 mb low are promoting deep-layer southwesterly flow across AZ, with a conveyor belt of deep moisture supporting widespread moderate to heavy precipitation to the region. Sub-freezing vertical profiles above 6000 ft should support mainly snow across the higher-terrain areas of the Mogollon Rim. Strong 850-700 mb warm-air advection should provide ample moisture and lift within the -12 to -17C dendritic growth zone to support 2-3 inch/hr snowfall rates at times. By mid to late afternoon, a strongly forced line of low-topped convection is expected to develop across portions of central into southern AZ. It is possible that weak slantwise convection could develop later this afternoon to the rear of the convective line if weak, elevated instability can extend far enough north toward the Mogollon Rim. As such, a brief instance or two of snowfall rates over 3 inches/hr could occur. The heavier snow rates may begin as early as 17Z across the far south-central Coconino County area in association with the preceding conveyor belt of precipitation (per latest high-resolution guidance). Heavier snow should develop southeastward to southern Apache County (near the NM border) from roughly 20Z-00Z in tandem with the post-squall line environment. ..Squitieri.. 01/01/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TWC...FGZ... LAT...LON 34941172 34251001 34010926 33650918 33470949 33781025 34231101 34481149 34821178 34941172 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0937 AM CST Sun Jan 01 2023 Valid 011700Z - 021200Z ...NO CRITICAL AREAS... The forecast remains on track with no changes required. Localized elevated conditions appear possible across southwest TX where RH is already falling into the low/mid 30s and far northeast NM in the immediate lee of terrain features. However, the expected coverage/duration of elevated conditions in both regions remains too limited for highlights. ..Moore.. 01/01/2023 .PREV DISCUSSION... /ISSUED 1151 PM CST Sat Dec 31 2022/ ...Synopsis... A strong mid-level trough will continue to advance into the Four Corners region through the day. By late afternoon, the stronger mid-level winds will begin to overspread parts of the southern High Plains. A surface low is expected to deepen within the Colorado Plateau. Some extension of this low pressure system will reach into the southern Plains as well. As this occurs, areas of breezy conditions are possible in parts of eastern New Mexico and West Texas. RH, however, will generally remain above critical thresholds aside from some localized values of 20-25%. Fire weather concerns will remain very localized today. ...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 1241 PM CST Sat Dec 31 2022 Valid 011200Z - 021200Z ...NO CRITICAL AREAS... The forecast remains on track with no changes required. Latest trends in guidance maintain low probability for sustained elevated conditions across the southern High Plains, though localized and brief elevated conditions remain possible across eastern NM and west TX. ..Moore.. 12/31/2022 .PREV DISCUSSION... /ISSUED 1143 PM CST Fri Dec 30 2022/ ...Synopsis... For Sunday, an upper-level trough will slowly approach the Four Corners. As upper-level flow will become more meridional across the southern Rockies, the surface trough is expected to be less pronounced than on Saturday. Even so, localized areas of 15-20 mph winds may develop in the southern High Plains region. Similar temperatures to Saturday coupled with perhaps slightly drier conditions could reduce RH in some locations to 20-25%. Fire weather concerns should continue to be minimal with perhaps some localized threat in eastern New Mexico/West Texas. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Sat Dec 31 18:44:02 UTC 2022.

MD 2080 CONCERNING HEAVY SNOW FOR THE HIGHER TERRAIN OF THE SIERRA IN NORTHERN CALIFORNIA
Mesoscale Discussion 2080 NWS Storm Prediction Center Norman OK 1141 AM CST Sat Dec 31 2022 Areas affected...the higher terrain of the Sierra in northern California Concerning...Heavy snow Valid 311741Z - 312345Z SUMMARY...Heavy snow is expected to increase in coverage across the higher terrain of the Sierra in northern California through the afternoon into early evening. DISCUSSION...A mid-level trough and accompanying stream of deep moisture continues to impinge on the higher terrain of the Sierra in northern CA. Strong deep-layer ascent along the windward side of the Sierra should lift the deep moisture to a saturated dendritic growth zone, favoring heavy snow production. The depth of the rich moisture, the presence of weak buoyancy, and combined orographic and dynamic lift of moist and buoyant air may foster snowfall rates up to the 3-5 inch/hr range, at least on a localized basis and particularly above 6000 ft elevations. Latest high-resolution guidance consensus suggests that the heavier snowfall rates should begin sometime between 18-20Z and become more widespread in the higher elevations in the 21-01Z time frame. ..Squitieri.. 12/31/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...VEF...REV...HNX...STO... LAT...LON 39692049 38941999 38391942 38141925 37741893 37481857 37191831 36961835 36991866 37421925 37921972 38642031 39062057 39332062 39682064 39692049 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1100 AM CST Sat Dec 31 2022 Valid 011200Z - 021200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Sunday. ...Synopsis and Discussion... A large-scale upper trough will move quickly eastward across much of the western CONUS on Sunday. A related surface low should develop over the Great Basin and track eastward toward the central Rockies. Occasional lightning flashes will be possible across the parts of the Southwest as mid-level lapse rates steepen and strong ascent occurs with enhanced deep-layer southwesterly flow. Weak instability across this region is expected to limit the threat for organized severe thunderstorms. Farther east, low-level moisture is forecast to return northward across south/east TX into eastern OK and AR/LA overnight Sunday into early Monday morning. A few lightning flashes may occur with isolated thunderstorms in the strong low-level warm advection regime, but convective coverage should be sparse owing to a substantial cap. ..Gleason.. 12/31/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1027 AM CST Sat Dec 31 2022 Valid 311630Z - 011200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHEAST TODAY... ...SUMMARY... Isolated strong to severe thunderstorms capable of locally damaging gusts and a brief/weak tornado or two are possible across parts of the Southeast today. ...Synopsis... A broad large-scale trough over the MS Valley will deamplify as it advances slowly east-northeastward through the period. Within the base of the trough, a shortwave impulse (evident in water vapor imagery) will lift northeastward from the Lower MS/TN Valleys through the Appalachians -- emerging off the New England coast by the end of the period. In the low-levels, a weak quasi-stationary baroclinic zone will remain draped from the central Gulf Coast northeastward toward the Mid-Atlantic. While the mass response at the surface (accompanying the midlevel impulse) will not be particularly strong -- characterized by weak/gradually veering surface winds across the warm/moist sector -- strengthening unidirectional southwesterly flow with height and a northeastward-advancing low-level jet will provide sufficient deep-layer shear for a few organized storms across parts of the Southeast (with more conditional potential into the Mid-Atlantic). ...FL Panhandle into southeastern SC... Low-level confluence (albeit weak) is gradually increasing over the Southeast in the vicinity of a strengthening low-level jet, which combined with glancing large-scale ascent accompanying the midlevel impulse should favor an uptick in thunderstorm development this afternoon. While widespread cloud coverage and elevated showers over the area will limit diurnal destabilization, deep boundary-layer moisture (with middle/upper 60s dewpoints) should support isolated surface-based storms focused along the confluence axis. Surface-based storms will be most likely over areas that can warm into the lower 70s this afternoon. While poor midlevel lapse rates/weak buoyancy may limit convective intensity, any storms that become surface-based could be loosely organized given 40-50 kt of effective shear (characterized by a long/straight hodograph). Locally damaging gusts will be the main concern with this activity -- especially with any constructive cell mergers/local clustering amid minimal CINH -- though a brief/weak tornado cannot be ruled out with any sustained supercell structures. ...Mid-Atlantic... A more conditional severe risk could spread northeastward into the Mid-Atlantic this afternoon, where strong/mainly unidirectional deep-layer shear will develop amid middle/upper 60s dewpoints. However, lingering stable layers above the boundary layer and generally weak forcing limits confidence in robust storm development over this area -- precluding severe probabilities at this time. ..Weinman/Hart.. 12/31/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0924 AM CST Sat Dec 31 2022 Valid 311700Z - 011200Z ...NO CRITICAL AREAS... The forecast remains on track with no changes needed. Latest guidance maintains low probability for substantial overlap of near 20% RH (most likely across the OK/TX Panhandles) and 15+ mph winds (most likely across west/northwest TX). See the previous discussion for additional details. ..Moore.. 12/31/2022 .PREV DISCUSSION... /ISSUED 1142 PM CST Fri Dec 30 2022/ ...Synopsis... Shortwave ridging will build across the southern Plains as an upper-level trough digs into southern California today. With a modest increase in mid-level winds across the southern Rockies, a lee trough will deepen in the High Plains. Surface winds in eastern New Mexico and western Texas will increase by the afternoon to 15-20 mph. Despite the breezy conditions, RH is not expected to drop below critical thresholds. Fire weather concerns will remain localized. ...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 1234 PM CST Fri Dec 30 2022 Valid 311200Z - 011200Z ...NO CRITICAL AREAS... The previous forecast remains on track with no changes needed. Despite increasing winds, recent ensemble guidance maintains low probabilities for RH values below critical thresholds across the southern Plains. See the previous discussion below for additional details. ..Moore.. 12/30/2022 .PREV DISCUSSION... /ISSUED 1142 PM CST Thu Dec 29 2022/ ...Synopsis... On Saturday, a shortwave upper-level ridge will move over the southern Plains. This will occur in advance of another upper-level trough that will be digging into southern California and parts of the Southwest by Sunday morning. Stronger mid-level winds will continue across the southern Rockies. A deeper lee trough in the central/southern High Plains is expected as compared to Friday. This should act to increase wind speeds in eastern New Mexico and West Texas. Despite stronger surface winds, temperatures are still expected to remain cool enough to keep RH above critical thresholds. Fire weather concerns are expected to remain too localized for highlights. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Fri Dec 30 18:37:02 UTC 2022.

No Mesoscale Discussions are in effect as of Fri Dec 30 18:37:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1052 AM CST Fri Dec 30 2022 Valid 311200Z - 011200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe thunderstorms remain possible across parts of the Southeast tomorrow/Saturday evening. ...Synopsis... A mid-level trough will traverse the Southeast as a second upper trough impinges on the California Coastline tomorrow/Saturday. Across the southeastern quadrant of the CONUS, adequate low-level moisture will advect northward from the Gulf of Mexico in advance of a weak surface low accompanying the mid-level trough. Strong flow aloft overspreading the low-level moisture will provide adequate buoyancy, shear, and lift for organized thunderstorms across the Southeast, with a couple of strong to severe thunderstorms possible. ...Southeast... The onset of diurnal heating will support surface temperatures and dewpoints rising into the 60s to near 70 F, with tall and thin (500-1000 J/kg) MLCAPE evident in point forecast soundings given modest tropospheric lapse rates. Southwesterly 850 mb flow exceeding 35 kts, with even stronger flow aloft, will promote elongated hodographs and associated 40+ kts of effective speed shear for some storm organization. The severe threat is expected to remain relatively isolated given limited instability. Nonetheless, some of the stronger storms may produce a couple of damaging gusts or perhaps a brief tornado or two, starting from the FL/AL coastline area during the late morning hours and progressing eastward with time to portions of southern SC by early evening. ..Squitieri.. 12/30/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1001 AM CST Fri Dec 30 2022 Valid 301630Z - 311200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON OVER PARTS OF THE CENTRAL GULF COAST REGION... ...SUMMARY... Isolated damaging gusts and a brief tornado or two are possible this afternoon near the central Gulf Coast. ...Central Gulf Coast... A line of thunderstorms continues to progress eastward across parts of southeast LA and southern MS. It appears that these storms have likely peaked in intensity, and are now moving into a progressively drier and more stable low-level air mass. Nevertheless, the strongest cells will remain capable of isolated gusty/damaging wind gusts or a brief spin up for another few hours. Please refer to MCD #2079 for further details. ..Hart/Weinman.. 12/30/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0955 AM CST Fri Dec 30 2022 Valid 301700Z - 311200Z ...NO CRITICAL AREAS... The forecast remains on track with no changes required. Afternoon RH reductions into the upper 20s/low 30s are likely across parts of the southern High Plains amid scattered clouds, and winds are expected to remain near/below 15 mph for most locations. ..Moore.. 12/30/2022 .PREV DISCUSSION... /ISSUED 1141 PM CST Thu Dec 29 2022/ ...Synopsis... A southern stream shortwave trough will move from the lower Texas Gulf Coast into the central Gulf Coast region today. Moderate mid-level winds will be present across the southern Rockies in the wake of the trough. A weak lee trough is expected to develop in the central and southern High Plains. While it is possible some locally elevated conditions could develop in parts of eastern New Mexico and West Texas, broader winds are expected to remain weak and some lingering cloud cover and cooler temperatures will also tend to keep RH higher. Fire weather concerns should remain low. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Thu Dec 29 17:59:01 UTC 2022.

MD 2074 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF EASTERN TEXAS INTO WESTERN LOUISIANA
Mesoscale Discussion 2074 NWS Storm Prediction Center Norman OK 1151 AM CST Thu Dec 29 2022 Areas affected...portions of eastern Texas into western Louisiana Concerning...Severe potential...Watch unlikely Valid 291751Z - 292015Z Probability of Watch Issuance...20 percent SUMMARY...A few strong to severe thunderstorms may develop through late afternoon. A couple damaging gusts and perhaps a brief tornado or instance of marginal severe hail may occur. The sparse severe threat suggests a WW issuance is not currently needed. DISCUSSION...MRMS mosaic/regional radar and water vapor satellite imagery shows a gradual intensification of semi-discrete convection embedded within confluence bands across western LA associated with a WAA regime. 30 dBZ echo tops have recently been reaching the 30-45 kft range, with individual embedded cells showing brief bouts of weak, transient low-level rotation. The mid-level trough continues to slowly approach from the rest, resulting in a gradual intensification of deep-layer speed shear per latest mesoanalysis fields. RAP analysis fields also show an embedded 500 mb max across central TX slowly approaching the MS Valley, which should further augment deep-layer ascent. In addition, continued insolation of a fairly moist low-level airmass is contributing to MLCAPE reaching 1000 J/kg. The increasing lift, buoyancy and shear should foster continued trends of storm organization and intensification through the afternoon. However, MLCAPE should be constrained to tall-thin profiles given 6-7 C/km mid-level lapse rates, and low-level directional shear should also remain modest (especially around 3 km, as shown by weaknesses in the latest KPOE VAD profiler data). As such, expected storm modes should be brief LEWPS/transient supercells capable of supporting a couple of strong wind gusts and perhaps a bout of marginal severe hail or a brief tornado. Given the likely isolated nature of the severe threat, a WW issuance is not currently anticipated. Additional rounds of thunderstorms (perhaps severe) are likely later this evening into tonight, though this threat also appears to be isolated. Nonetheless, later severe potential may be addressed by additional MCDs as needed. ..Squitieri/Thompson.. 12/29/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LZK...LCH...SHV...HGX...FWD...EWX... LAT...LON 30049714 32069550 33369422 33439308 33059262 32389245 31599255 30919291 30419364 29989447 29669541 30049714 Read more