Severe Storms

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0305 PM CDT Mon Jul 17 2023 Valid 172000Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL/SOUTHERN HIGH PLAINS TO THE OHIO VALLEY AND FROM EASTERN WYOMING SOUTHEAST INTO SOUTHWEST SOUTH DAKOTA AND NORTHERN NEBRASKA... ...SUMMARY... Severe storms producing large hail and damaging wind gusts are mainly expected from the Black Hills southeastward into Nebraska tonight, and across portions of the Ozarks and Lower Ohio Valley today. Shifted the slight/marginal risk farther north across the Ohio Valley to account for current location of the cold front and the threat for additional strong to severe thunderstorms. See MCD 1598 and 1599 for additional information. Expanded the marginal risk farther north into central Arizona. Thunderstorms are developing along the Gila Range with enough convective coverage for a potential cluster/cold pool to develop. The HRRR has trended toward this solution with the potential for some stronger wind gusts in a westward moving cluster this evening. Final change was expansion of the significant hail area across Missouri, into far western Illinois, and more of Kansas. The 18Z KSGF RAOB supports the potential for significant hail with nearly 4000 J/kg MLCAPE and 40 knots of effective shear. Storm mode will be the primary question as recent radar trends show significant upscale growth across central Missouri. This could mitigate the significant hail threat in that region and increase the potential for a concentrated severe wind swath. However, confidence is low how this cluster may evolve. Elsewhere, no changes were necessary. See MCD 1597 for information about northeast Oklahoma. ..Bentley.. 07/17/2023 .PREV DISCUSSION... /ISSUED 1153 AM CDT Mon Jul 17 2023/ ...Central/southern Plains east Ozarks and Ohio Valley... Moderately strong northwest/west mid-level flow will persist from the central/southern Plains east to the OH Valley through tonight. Heating of a moist air mass ahead of a nearly stationary front, combined with a plume of steep mid-level lapse rates will result in a rather large region of strong to locally extreme instability in the presence of substantial deep-layer shear supportive of organized storms. Ongoing severe storm cluster over southeast KS will likely continue moving south-southeast into an environment characterized by 40-50 kts of shear and MLCAPE of 3000-4000 J/jg. Damaging winds and potentially very large hail will be possible with this complex as it moves across northeast OK. Additional thunderstorm development is likely across the Ozarks vicinity along remnant outflow boundaries this afternoon, ultimately resulting in additional clusters or line segments moving southeast/south through this evening. Damaging winds will be the primary severe threat, and with large (isolated very large) hail with the more discrete/intense updrafts. Across the OH Valley, clusters of thunderstorms are expected to develop as clearing/heating occurs in the wake of morning storms. Effective shear of 30-40 kts will support both supercell and multicell clusters persisting through the late afternoon and early evening with severe wind/hail potential. ...Eastern Wyoming/Black Hills/Nebraska... A sharpening lee trough ahead of the northern Rockies upper trough will result in moist low-level upslope flow into the Black Hills/eastern Wyoming and southeast Montana vicinity. The proximity of the upper ridge may somewhat temper the extent of deeper convection, however at least isolated thunderstorms are expected to develop by late afternoon/early evening in a moderately unstable and strongly sheared environment, with storms increasing in coverage toward/after sunset. Steep lapse rates and long straight hodographs will support large to locally very large (greater than 2 inch diameter) hail. As the low-level jet strengthens during the evening, upscale development into a bowing MCS is possible as convection tracks southeastward across western/southern South Dakota and Nebraska. Damaging gusts, potentially significant, may accompany this MCS during the evening and overnight hours, and a Significant Wind area has been added with this outlook. ...Northern Great Basin and Central/Eastern Montana... Moderate to strong west-southwest mid/upper-level flow will overspread the region ahead of the northern Rockies upper trough. Steep mid-level lapse rates and moistening will support MLCAPE around 500-1250 J/kg. Well-mixed boundary layers will result in mostly high-based, low-precipitation convection capable of sporadic strong dry microburst winds from far northeast Nevada/northern Utah into central Montana. With eastward extent into parts of eastern Montana, deeper boundary-layer moisture will result in the potential for isolated strong gusts as well as hail. ...Southern AZ... Diurnal heating of a moist environment (PW 1.5 inches) will contribute to afternoon MLCAPE of 1000-1500 J/kg. Thunderstorm development is expected this afternoon, and dry mid-levels with 15-20 kts of easterly flow will result in a risk for gusty/damaging winds as storms move west through evening. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0210 PM CDT Mon Jul 17 2023 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Eastern Great Basin and the Western Slope... On the fringes of the upper ridge, weak forcing for ascent and mid-level moisture will likely support isolated thunderstorms across portions of the eastern Great Basin and western Rockies Day2/Tuesday. Model soundings show relatively slow storm motions with PWATS near or approaching 1 inch. While fuels are somewhat receptive to lightning strikes, the mixed storm mode will likely favor lower ignition potential with these storms. While a few drier lightning strikes are possible, dry thunder coverage appears too low to introduce probabilities. Please see the previous discussion for more information. ..Lyons.. 07/17/2023 .PREV DISCUSSION... /ISSUED 0200 AM CDT Mon Jul 17 2023/ ...Synopsis... For Tuesday, the upper-level trough within the Northwest will continue to the east into the northern Rockies and adjacent Plains. At the surface, a trough in the lee of the Rockies will shift east while a surface low develops in eastern Colorado and moves into Kansas/Oklahoma. ...Permian Basin... The deepening surface low will increase surface wind speeds from the Texas Panhandle into the Permian Basin. Wind speeds will be higher in the north and drop to 15 mph to the south. Fuels are only dry within the Permian Basin. While RH could fall to below 15% in some areas, winds will generally be to weak for fire weather concerns. ...Great Basin... With the upper-level anticyclone shifting east, some mid-level moisture return is possible into the Great Basin. Mid-level winds will remain enhanced along the southern flank of the passing trough to the north. Thunderstorms within Nevada/Utah could be a mix of wet and dry. While approaching critically dry in some areas, fuels are not overly receptive at this time. ...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 1229 PM CDT Mon Jul 17 2023 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE LOWER-MISSOURI/MID-MISSISSIPPI VALLEY... ...SUMMARY... Thunderstorms associated with large hail and damaging wind gusts will be possible Tuesday evening into the overnight across parts of the mid Mississippi/Lower-Missouri Valley. Other strong to severe storms will also be possible in various parts of the CONUS from the Great Basin and the Plains to the Midwest and East Coast. ...Synopsis... The upper level pattern on Tuesday will feature a flat ridge across the western CONUS with a mid-level shortwave trough crossing Montana, another mid-level shortwave trough across the Corn Belt and a broader trough across the Great Lakes into the Northeast. The surface pattern will more nebulous with a diffuse surface front extending from the Northeast across the southern Great Lakes and into the Plains. Across the Plains, it will be a more defined warm front with a surface low across Kansas. This front will extend north from that surface low into the northern Plains. ...Lower Missouri Valley/Mid-Mississippi Valley/Lower Ohio Valley and Vicinity... Thunderstorms will likely be ongoing at the beginning of the period in one or more locations along a zone of mid-level frontogenesis extending from southeast South Dakota to northern Arkansas. Mid level height falls and the associated low-level jet response are expected to overspread the frontal zone between 06 and 12Z, but forecast soundings along this zone show varying low-level moisture which likely explains the variance in convective coverage along this zone from 12Z CAM guidance. This morning convection will have a significant impact on the forecast in the region. More widespread morning convection and development of a cold pool could support a severe weather threat tomorrow morning and continuing through the afternoon. However, if this does not occur, the warm sector would likely remain mostly capped during the day. Regardless of the evolution of morning convection, the signal remains strong for elevated convection along the Mississippi River near St. Louis during the overnight period as a 40-50 knot low-level jet develops across eastern Missouri amid 2000+ J/kg MUCAPE and 45-50 knots of mid-level flow. This will support the potential for elevated supercells along this zone starting between 04Z and 07Z late Tuesday night. Eventually these storms may grow into a forward propagating MCS with a severe wind threat into portions of western Kentucky/northern Tennessee early Wednesday morning. ...Northern Plains... Thunderstorms are expected across the northern Plains on Tuesday afternoon as cyclonic vorticity advection overspreads the region near peak heating. MLCAPE around 2000 to 2500 J/kg amid 35 to 40 knots of effective shear should support supercells developing along the frontal zone. Boundary normal flow should keep convection discrete and perhaps somewhat isolated. If more widespread storm coverage is anticipated, a slight risk may be needed for this region in later outlooks. ...Central High Plains... A few thunderstorms are possible late Tuesday afternoon as low-level flow veers from northeasterly to easterly and becomes more upslope with low-level moisture advection on the northern periphery of the surface cyclone. The favorable period may be relatively short lived since moisture arrives late, but a favorable environment may develop with 2000+ J/kg MLCAPE and a supercell wind profile. ...Eastern Carolinas to the Northeast... A broad region of weak ascent is expected from the Appalachians eastward as a mid-level trough translates eastward. Ahead of this trough, pockets of strong instability are expected to develop with the greatest instability across the eastern Carolinas. The most favorable shear is expected across portions of the Northeast where long, straight hodographs could support some supercells capable of large hail and damaging wind gusts. ...Great Basin... A deeply mixed airmass is expected Tuesday across the Great Basin with ample instability for scattered thunderstorms across much of the region. A belt of stronger mid-level flow around 30 knots will exist from east-central Nevada and across north-central Utah. This may support some storm organization with the potential for isolated severe wind gusts given the deeply mixed sub-cloud layer. ..Bentley.. 07/17/2023 Read more

MD 1583 CONCERNING SEVERE THUNDERSTORM WATCH 500... FOR CENTRAL KANSAS
Mesoscale Discussion 1583 NWS Storm Prediction Center Norman OK 0519 PM CDT Sun Jul 16 2023 Areas affected...Central Kansas Concerning...Severe Thunderstorm Watch 500... Valid 162219Z - 170015Z The severe weather threat for Severe Thunderstorm Watch 500 continues. SUMMARY...A supercell capable of large/very large hail and severe wind gusts will likely continue to the south/southwest in central Kansas. Additional development is possible in west-central Kansas. Later this evening, the low-level jet could promote storm development in east-central/southeastern Kansas. DISCUSSION...A large supercell in central Kansas near I-70 has produced hail of 1.25-3 inches in the last hour or so. Measured severe wind gusts have also been observed along the western flank of the storm (recently 70 mph in Russell). Current observational trends in central Kansas show a pocket of dry/well-mixed air in the vicinity of Wichita. Greater moisture exists along an axis from Great Bend to Pratt. It is likely that this supercell will continue to track south to perhaps a bit southwest this afternoon. Strong effective shear and buoyancy will continue to support a threat for large/very large hail and severe wind gusts. Additional convection has attempted to develop and mature farther west along the outflow boundary. Should that occur some upscale growth is possible and severe winds would become more probable. Low-level shear is weak per area VAD profiles, and the tornado threat is generally low as a result. The exception would be along the outflow into southeastern Kansas, though storms are not likely to develop there in the near term. Eastern portions of WW 500 will likely not see much activity in the short term. With a modest increase in the low-level jet expected this evening, the outflow boundary will need to be monitored for convective development. Forecast soundings suggest those potential storms would pose a similar threat of large hail and severe/damaging winds. ..Wendt.. 07/16/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TOP...ICT...GID...DDC... LAT...LON 38469965 38999919 39179876 39249842 39259818 39229789 39099780 37759797 37409800 37119830 37129913 37659982 38469965 Read more

WW 0501 Status Updates
STATUS REPORT ON WW 501 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..DEAN..07/16/23 ATTN...WFO...JAN...LCH...LIX... STATUS REPORT FOR WS 501 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ARC003-162240- AR . ARKANSAS COUNTIES INCLUDED ARE ASHLEY LAC009-025-029-035-037-041-065-067-077-079-083-091-107-123-125- 162240- LA . LOUISIANA PARISHES INCLUDED ARE AVOYELLES CATAHOULA CONCORDIA EAST CARROLL EAST FELICIANA FRANKLIN MADISON MOREHOUSE POINTE COUPEE RAPIDES RICHLAND ST. HELENA TENSAS WEST CARROLL WEST FELICIANA MSC001-005-021-029-037-049-055-063-085-113-149-157-162240- MS . MISSISSIPPI COUNTIES INCLUDED ARE Read more

WW 501 SEVERE TSTM AR LA MS 162050Z - 170300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 501 NWS Storm Prediction Center Norman OK 350 PM CDT Sun Jul 16 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Extreme southeast Arkansas Northeast and east-central Louisiana Southwest Mississippi * Effective this Sunday afternoon and evening from 350 PM until 1000 PM CDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible SUMMARY...A fast-moving complex of severe thunderstorms will move southeast across the watch area through early this evening with a risk for damaging winds. The severe thunderstorm watch area is approximately along and 75 statute miles north and south of a line from 55 miles northwest of Natchez MS to 45 miles east of Natchez MS. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU1). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 498...WW 499...WW 500... AVIATION...A few severe thunderstorms with hail surface and aloft to 0.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 29035. ...Bunting Read more

WW 0498 Status Updates
STATUS REPORT ON WW 498 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 WNW IER TO 40 NNE IER TO 40 SW MLU TO 25 SW MLU TO 20 NW MLU TO 20 NNE ELD. ..DEAN..07/16/23 ATTN...WFO...SHV... STATUS REPORT FOR WS 498 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ARC139-162240- AR . ARKANSAS COUNTIES INCLUDED ARE UNION LAC021-043-059-069-073-111-127-162240- LA . LOUISIANA PARISHES INCLUDED ARE CALDWELL GRANT LA SALLE NATCHITOCHES OUACHITA UNION WINN THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 0499 Status Updates
STATUS REPORT ON WW 499 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 5 SSW UNO TO 15 S ALN TO 20 WSW SPI. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1582 ..DEAN..07/16/23 ATTN...WFO...LSX...SGF... STATUS REPORT FOR WS 499 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC005-027-051-117-119-121-133-135-157-163-189-162240- IL . ILLINOIS COUNTIES INCLUDED ARE BOND CLINTON FAYETTE MACOUPIN MADISON MARION MONROE MONTGOMERY RANDOLPH ST. CLAIR WASHINGTON MOC093-179-186-187-203-162240- MO . MISSOURI COUNTIES INCLUDED ARE IRON REYNOLDS STE. GENEVIEVE ST. FRANCOIS SHANNON THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES Read more

WW 499 SEVERE TSTM IL MO 161920Z - 170200Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 499 NWS Storm Prediction Center Norman OK 220 PM CDT Sun Jul 16 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Western Illinois Central and eastern Missouri * Effective this Sunday afternoon and evening from 220 PM until 900 PM CDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Scattered severe thunderstorms will move east-southeast a cross the watch area this afternoon and evening with a risk for damaging winds, and isolated large hail. The severe thunderstorm watch area is approximately along and 55 statute miles east and west of a line from 20 miles north northeast of Alton IL to 40 miles south of Fort Leonard Wood MO. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU9). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 498... AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 28025. ...Bunting Read more

WW 0500 Status Updates
STATUS REPORT ON WW 500 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..WENDT..07/16/23 ATTN...WFO...ICT...TOP...DDC...GLD...GID... STATUS REPORT FOR WS 500 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS KSC009-015-017-027-029-041-047-051-053-055-057-061-063-065-069- 079-083-095-097-101-105-113-115-123-127-135-141-143-145-151-155- 159-161-163-165-167-169-171-173-179-185-195-162240- KS . KANSAS COUNTIES INCLUDED ARE BARTON BUTLER CHASE CLAY CLOUD DICKINSON EDWARDS ELLIS ELLSWORTH FINNEY FORD GEARY GOVE GRAHAM GRAY HARVEY HODGEMAN KINGMAN KIOWA LANE LINCOLN MCPHERSON MARION MITCHELL MORRIS NESS OSBORNE OTTAWA PAWNEE PRATT RENO RICE RILEY ROOKS RUSH RUSSELL SALINE SCOTT SEDGWICK SHERIDAN STAFFORD TREGO THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES Read more

WW 500 SEVERE TSTM KS 162025Z - 170300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 500 NWS Storm Prediction Center Norman OK 325 PM CDT Sun Jul 16 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Western and central Kansas * Effective this Sunday afternoon and evening from 325 PM until 1000 PM CDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2 inches in diameter possible Scattered damaging wind gusts to 70 mph possible SUMMARY...Severe thunderstorms will move southeast across the watch area the remainder of this afternoon and evening with a risk for large hail and damaging wind gusts. The severe thunderstorm watch area is approximately along and 60 statute miles north and south of a line from 70 miles northwest of Dodge City KS to 40 miles south southeast of Manhattan KS. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU0). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 498...WW 499... AVIATION...A few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 29025. ...Bunting Read more

MD 1582 CONCERNING SEVERE THUNDERSTORM WATCH 499... FOR FAR SOUTHEASTERN MO AND SOUTHERN IL
Mesoscale Discussion 1582 NWS Storm Prediction Center Norman OK 0400 PM CDT Sun Jul 16 2023 Areas affected...Far southeastern MO and southern IL Concerning...Severe Thunderstorm Watch 499... Valid 162100Z - 162230Z The severe weather threat for Severe Thunderstorm Watch 499 continues. SUMMARY...The severe-wind risk continues across Severe Thunderstorm Watch 499 this afternoon. Convective trends are being monitored for a possible downstream watch. DISCUSSION...Latest radar data from KLSX depicts a broken line of thunderstorms tracking eastward across parts of southeastern MO into southwestern IL this afternoon -- where several wind-damage reports and measured severe gusts have occurred. In the short-term, severe winds and sporadic large hail will remain possible with this activity -- aided by a unidirectional westerly wind profile characterized by 30 kt of 0-6 km bulk shear (per KLSX VWP data) oriented perpendicular to the larger outflow boundary. As these storms continue east out of Severe Thunderstorm Watch 499, it is unclear if storms will maintain intensity (especially along the southern parts of the broken line) where deep-layer shear is weaker. However, steep low-level lapse rates and favorable deep-layer shear downstream of the northern part of the line may continue to support organized clusters capable of wind damage. Convective trends are being monitored for a downstream watch. ..Weinman/Bunting.. 07/16/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PAH...ILX...LSX... LAT...LON 37729068 38069060 39188979 39518950 39638910 39648851 39538797 39228770 38788776 38428795 37938827 37518874 37358910 37278950 37239018 37349051 37549068 37729068 Read more

MD 1580 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF WESTERN SD INTO FAR NORTHWESTERN NE
Mesoscale Discussion 1580 NWS Storm Prediction Center Norman OK 0331 PM CDT Sun Jul 16 2023 Areas affected...Parts of western SD into far northwestern NE Concerning...Severe potential...Watch unlikely Valid 162031Z - 162300Z Probability of Watch Issuance...20 percent SUMMARY...Isolated large hail and locally severe gusts are possible with any storms that can develop across the area this afternoon. DISCUSSION...Latest visible satellite imagery indicates deepening boundary-layer cumulus generally focused over the Black Hills and a NW/SE-oriented pre-frontal confluence zone over southwestern SD this afternoon. Modified RAP forecast soundings over this area depict an uncapped air mass, characterized by steep midlevel lapse rates atop moist northeasterly low-level flow. Continued heating over the higher terrain and along the confluence zone may support isolated thunderstorm development during the next couple of hours, though storm coverage is uncertain given weak large-scale ascent over the area. If storms can develop, a long/straight hodograph (50-60 kt of effective shear) would support splitting supercells capable of producing large hail and locally severe gusts. Additionally, a back-door cold front will approach the area during the next few hours, which may also support an uptick in thunderstorms though the evening. While a watch is not currently expected given uncertainty on storm development/coverage, trends will be monitored. ..Weinman/Bunting.. 07/16/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...UNR...CYS... LAT...LON 42720350 42980373 43250389 43550399 43860401 44170402 44440401 44740397 44930377 45000343 44820296 44420227 43870163 43400133 43010140 42590189 42420233 42390281 42550324 42720350 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Jul 16 2023 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM KANSAS INTO MISSOURI...AND OVER NORTHERN LOUISIANA... ...SUMMARY... A brief/weak tornado will be possible across portions of the Northeast this afternoon, while scattered large hail and severe wind will be possible across the Central Plains and portions of the Midwest. ...Northeast... Low-level shear continues to decrease over New England, though instability remains. As such have reduced tornado probabilities, although heating over NY/VT may yield a few strong cells in the weaker shear area. The strong low-level shear has shifted primarily northeast of where the more favorable instability resides. ...Sabine Valley into the mid MS Valley... A corridor of strong instability exists ahead of ongoing strong to severe storms now near the AR/LA border. These may pose a damaging wind threat as they likely persist today, traveling southeastward across northern LA. For more information see mesoscale discussion 1578. Farther north, scattered strong cells persist over east-central MO, where strong outflow winds have been observed. The air mass remains unstable eastward into IL, and both strong gusts and marginal hail may occur with MLCAPE to 2000 J/kg and around 30 kt effective shear. ...Central/Northern Plains... Strong heating continues over the region, with increasing CU noted on satellite near the boundary in KS. Convection is also growing over the Black Hills area, through storm coverage should remain isolated there. Favorable 50 kt effective shear will conditionally favor hail cells. The greatest threat area continues to be over KS where heating continues and the air mass is most unstable south of the front. For more information see mesoscale discussion 1579. ..Jewell.. 07/16/2023 .PREV DISCUSSION... /ISSUED 1137 AM CDT Sun Jul 16 2023/ ...Northeast/Southern New England and Mid-Atlantic States... Widespread precipitation, with embedded stronger convective elements, continues across eastern portions of the mid-Atlantic region northeast into New England at 16z. Widespread cloud cover/limited heating has tempered destabilization of a very moist air mass (PW in excess of 2 inches), however weak MLCAPE (500 to locally near 1000 J/kg) is expected through this afternoon, which will remain sufficient for a few stronger storms to persist. Low-level shear will also remain supportive of mostly transient low-level rotation and some continued tornado risk through mid afternoon. ...Central Plains/Midwest... A persistent low-level jet will continue to provide a moist/unstable inflow into the MCS over eastern KS/western MO, and diurnal heating downstream over central MO will result in moderate/strong MLCAPE as this MCS continues moving east-southeast over the next few hours. Mid-level flow of 30-40 kts will provide sufficient shear to maintain some degree of organization with at least some risk for damaging winds this afternoon. The Marginal Risk has been expanded northwest towards the Black Hills Region of SD, where isolated thunderstorms may develop this afternoon/evening. Northwesterly mid-level flow of 40-50 kts will support supercell potential with a risk for severe hail and strong wind gusts. ...North Texas/Southern Oklahoma to ArkLaTex/Middle Gulf Coast... A persistent MCS continues along the Red River late this morning, with isolated severe winds reported over the past hour. Daytime heating of an exceptionally moist air mass will contribute to strong/locally extreme instability by afternoon downstream towards the Arklatex, and despite marginal shear this convective system will likely maintain its structure while moving southeast this afternoon. At least isolated damaging winds will be possible with this MCS through the afternoon, and also with additional storms/clusters that may develop towards the middle Gulf Coast within an uncapped air mass. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0154 PM CDT Sun Jul 16 2023 Valid 171200Z - 181200Z A belt of enhanced low-level flow will develop across portions of northeast Utah, northwest Colorado, and southern Wyoming. Here winds around 20-25 mph (with stronger gusts) will develop during the afternoon, in the presence of relative humidity around 10 percent. The result will be critical meteorological conditions. However, NFDRSv4 derived ERC percentiles are still only in the 60-80 percent range. Thus have opted to go with an Elevated area instead of Critical. Elsewhere, only minor changes were made to the periphery of the Elevated area in the Pacific Northwest to bring into better alignment with the latest guidance. ..Marsh.. 07/16/2023 .PREV DISCUSSION... /ISSUED 0140 AM CDT Sun Jul 16 2023/ ...Synopsis... Strong cyclonic flow will remain present over the Northwest on Monday. A cold front will accompany the trough passage in the Northwest and will progress into the Great Basin. ...Columbia Basin... Surface winds behind the cold front will likely reach 15-20 mph. For areas near the terrain, 20-25 mph could also occur. Temperatures will be slightly cooler and some mid/high-level cloud cover will be possible as well. Due to those factors, RH will likely only be marginally dry. Most areas will reach around 20% during the afternoon. Despite winds being stronger on a broader scale, only elevated fire weather conditions are expected due marginal RH. ...Great Basin... The shortwave trough moving through northern California late Sunday will continue into the northern Basin on Monday. This may promote isolated thunderstorms during the afternoon. These storms will be fast moving and produce limited precipitation. With fuels only marginally dry at best from northern Nevada into southern Idaho, the threat of lightning ignitions should remain low. Ahead of the cold front, southwesterly winds will increase across southern and central Nevada. Current guidance shows 10-20% RH will occur during the afternoon. The strongest winds, however, will occur over central Nevada where fuels are not critically dry. Locally elevated conditions will remain possible in southern Nevada where fuels are cured. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0497 Status Updates
STATUS REPORT ON WW 497 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 15 ENE BOS TO 20 N BOS TO 35 NNW PWM. WW 497 WILL BE ALLOWED TO EXPIRE AT 161900Z. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1576 ..GLEASON..07/16/23 ATTN...WFO...OKX...BOX...ALY...GYX... STATUS REPORT FOR WT 497 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MEC005-031-161900- ME . MAINE COUNTIES INCLUDED ARE CUMBERLAND YORK MAC009-161900- MA . MASSACHUSETTS COUNTIES INCLUDED ARE ESSEX NHC015-017-161900- NH . NEW HAMPSHIRE COUNTIES INCLUDED ARE Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Sun Jul 16 2023 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE BLACK HILLS SOUTHEASTWARD INTO NEBRASKA... ...SUMMARY... Severe storms producing damaging hail and wind gusts are most likely from the Black Hills area southeastward into northern Nebraska late Monday. Other strong wind gusts or marginal hail will be possible from parts of Kentucky and Tennessee northeastward into western Pennsylvania. ...Synopsis... A large upper trough will remain situated from Ontario into the Great Lakes, providing cool air aloft and a cyclonic flow regime from Mid and Upper MS Valley into the Northeast. To the west, a shortwave trough will affect parts of the Pacific Northwest and into MT, with strong westerly flow aloft. East of there, a northwest flow regime will exist over the northern and central Plains, with embedded waves developing from eastern WY/MT into SD/NE in association with areas of storms late. At the surface, dry air will exist behind a cold front which will extend from northern KS/MO into northern IL/IN, with a plume of mid to upper 60s dewpoints ahead of it. Westerly flow around 850 mb will maintain an unstable air mass from KY/TN into OH and western PA, beneath moderate mid to upper level flow. ...Northern Plains... Ahead of the upper wave and near a deepening surface trough, storms are likely to develop over southeast MT and northern WY during the afternoon, moving southeast across SD through late evening and continuing into east-central/northeast NE overnight. Initial activity is likely to produce large hail with long hodographs and steep lapse rates aloft, although some of the activity may be elevated. Even so, substantial, penetrating downdrafts may yield wind damage as well, especially as storm mode transitions to MCS overnight into NE. ...KY/TN into western PA... Areas of storms may be ongoing Monday morning over parts of western KY and TN, and these would move into a destabilizing air mass during the day. As such, a few damaging gusts may occur assuming stronger instability develops ahead this potential activity. Forecast soundings show modest deep-layer shear around 30 kt, but steep lapse rates and sufficient mean wind to produce mobile cold pools and locally damaging winds. In addition, sporadic marginal hail will be possible with the more cellular activity given cool air aloft. Farther east, additional activity is possible from WV into eastern OH and western PA where heating will steep low-level lapse rates, and colder air aloft will exist near the midlevel temperature gradient. Marginal hail and locally strong gusts will be possible. ..Jewell.. 07/16/2023 Read more

No Mesoscale Discussions are in effect as of Sat Jul 15 22:15:24 UTC 2023.

No Mesoscale Discussions are in effect as of Sat Jul 15 22:15:24 UTC 2023.

WW 0495 Status Updates
STATUS REPORT ON WW 495 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..DEAN..07/15/23 ATTN...WFO...PUB...ABQ... STATUS REPORT FOR WS 495 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC071-152240- CO . COLORADO COUNTIES INCLUDED ARE LAS ANIMAS NMC007-019-021-033-037-047-059-152240- NM . NEW MEXICO COUNTIES INCLUDED ARE COLFAX GUADALUPE HARDING MORA QUAY SAN MIGUEL UNION THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more