Severe Storms

MD 1933 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF SOUTHEAST WYOMING INTO EXTREME NORTHEAST COLORADO...FAR SOUTHWESTERN SOUTH DAKOTA AND THE NEBRASKA PANHANDLE
Mesoscale Discussion 1933 NWS Storm Prediction Center Norman OK 0314 PM CDT Thu Aug 10 2023 Areas affected...portions of southeast Wyoming into extreme northeast Colorado...far southwestern South Dakota and the Nebraska Panhandle Concerning...Severe potential...Watch unlikely Valid 102014Z - 102245Z Probability of Watch Issuance...5 percent SUMMARY...A couple instances of severe hail/wind may accompany the stronger storms. A WW issuance is not expected. DISCUSSION...Convective initiation/intensification is underway across the Higher Terrain of WY/CO. Ahead of the developing storms, a well-mixed boundary layer has materialized, characterized by 30 F surface temperature/dewpoint spreads and 9-10 C/km 0-3 km lapse rates (per 20Z mesoanalysis). Forecast soundings depict around 500 J/kg of tall/thin MLCAPE, distributed in roughly the 700-300 mb layer. Given elongated hodographs, storms that can mature in this environment may produce a couple instances of severe hail/wind. However, the severe threat should be sparse and a WW issuance is not anticipated. ..Squitieri/Guyer.. 08/10/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...UNR...GLD...BOU...CYS... LAT...LON 40140221 40290348 40450419 40930471 41900547 42770588 43240579 43460519 43540445 43400372 43050327 42420276 41750235 40960217 40140221 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0245 PM CDT Thu Aug 10 2023 Valid 102000Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MID MISSOURI VALLEY AND VICINITY... ...SUMMARY... Isolated severe thunderstorms remain possible over parts of the eastern and central states this afternoon into tonight, including eastern North Carolina/southeast Virginia and parts of the Upper Midwest vicinity. ...Discussion... The main outlook adjustment being implemented in this update, aside from minor/local tweaks of the areal outlines, is an expansion of MRGL risk across the Iowa vicinity. Expectations are that an at least loosely organized MCS will move across the Iowa vicinity overnight, and that local/low-end severe potential may accompany the strongest cells. Otherwise, no appreciable changes appear necessary at this time. ..Goss.. 08/10/2023 .PREV DISCUSSION... /ISSUED 1139 AM CDT Thu Aug 10 2023/ ...Eastern Carolinas/southeast Virginia... A convectively augmented shortwave trough over the southern/central Appalachians will continue eastward today. A cluster of thunderstorms, likely MCV aided, is ongoing across coastal areas of the Carolinas at late morning. Although considerable cloud cover immediately preceding the cluster may be a thermodynamic hindrance, more appreciable destabilization is expected in more immediate coastal areas. Where storms intensify, a seasonally strong/cyclonically curved belt of westerlies (50+ kt at 500 mb) would support organized storms including the possibility of a few supercells and well-organized/moderately fast-moving clusters capable of wind damage and some tornado risk. Although uncertain, there is a scenario is which a secondary round of regional convective development occurs late this afternoon near the southeastward-moving weak front and/or preceding surface trough. While deep-layer shear will tend to weaken late this afternoon/early evening, wind profiles should conditionally remain supportive of well-organized storms, potentially including a few supercells. This could yield some storms capable of damaging winds, hail, and possibly a tornado, prior to the risk abating/shifting offshore by mid-evening. ...Dakotas/Upper Midwest and eastern Nebraska... As a mid/upper ridge shifts east, a low-amplitude trough will overspread the northern Great Plains. This will help induce a weak surface cyclone over western North Dakota with a surface trough arcing south into central Nebraska and a warm front extending southeast through southern Minnesota. Relatively modest boundary-layer moisture and deep-layer shear will be limiting factors to a more prolific severe threat across the region. But steeper mid-level lapse rates within an elevated mixed layer will spread east across most of South Dakota and much of Nebraska by early evening and support a confined corridor of moderate buoyancy with MLCAPE of 1000-2000 J/kg. Effective bulk shear of 25-35 kts should support a mixed mode of a few supercells and multicell clusters. The most likely zone for scattered thunderstorm development in the late afternoon should be near the surface trough/warm front intersection in the northeast South Dakota border area with ND/MN. Increasingly isolated development should trail south along the trough. A mix of large hail and severe wind gusts will be the main threats, with some potential that an MCS evolves and continues southeastward this evening. ...Mid-South/Tennessee Valley... Modifying outflow from early day thunderstorms should serve as a focus for redevelopment later this afternoon, along the remnant front to the north. Additionally, another round of low-level warm theta-e advection-driven storms should occur after sunset tonight. A modest combination of mid-level lapse rates and vertical shear should support a mainly isolated severe threat, with sporadic instances of damaging gusts and marginal hail possible. ...Coastal Mid-Atlantic/southern New England... Low-level warm theta-e advection will strengthen today and translate northeast from the Mid-Atlantic across New England this afternoon and evening. Low-topped convection (perhaps void of lighting flashes in some cases) should develop amid meager surface-based instability as thermodynamic profiles become saturated. Aside from localized wind damage, the potential for a brief tornado also exists owing to enlarged low-level hodograph curvature. ...Central High Plains... Isolated high-based thunderstorms should develop off the higher terrain of southeast Wyoming and far north-central Colorado near a lee surface trough. A deep mixed boundary layer along the adjacent High Plains could support a few severe wind gusts during the late afternoon to early evening. ...West-central/northwest Texas... Hot surface temperatures along the dryline may support isolated thunderstorm development late this afternoon and early evening. Should deep convection become sustained, the very deeply mixed boundary layer could yield a few severe-caliber wind gusts. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0247 PM CDT Thu Aug 10 2023 Valid 111200Z - 121200Z There are no changes needed to the current D2 Fire Weather Outlook. See previous discussion below. ..Thornton.. 08/10/2023 .PREV DISCUSSION... /ISSUED 0152 AM CDT Thu Aug 10 2023/ ...Synopsis... Fire weather concerns will persist across parts of Texas on Friday with more localized concerns possible over northern Montana. Broad northwesterly flow aloft over the northern half of the country will continue to support breezy conditions at the surface. Across the southern CONUS, monsoonal thunderstorms are expected across the Southwest with another day of anomalously hot temperatures over the southern Plains. ...Texas... Weak lee troughing along the High Plains will induce a broad southerly flow regime across the southern Plains. This will advect unseasonably hot temperatures northward into northwest TX/western OK where high temperatures are expected to peak near 105 F. Forecast guidance suggests winds will be regionally augmented in proximity to a thermal low over northwest TX and/or the TX Panhandle, which will increase the fire weather potential. Maximum sustained winds near 15 mph appear probable with afternoon RH in the 20-30% range. Recent reports from the region indicate that these wind/RH conditions are sufficient for active fire behavior, warranting highlights. Thunderstorms developing along the lee trough and/or in proximity to the low will pose a threat for gusty outflow winds and perhaps dry lightning strikes (ensemble guidance shows low probability for wetting rainfall Friday afternoon). ...Northern Montana... Dry northwesterly low to mid-level flow will persist across north-central MT from Thursday into Friday afternoon. A few deterministic solutions suggest that elevated fire weather conditions are possible with 15-20 mph winds and RH values falling into the low 20s. However, ensemble guidance shows considerably more spread in the wind/RH forecast with limited probability for sustained elevated conditions. This hinders confidence in a robust fire threat, but receptive fuels over northern MT will support a fire concern if confidence in elevated conditions improves. ...Dry Thunderstorms... Monsoonal moisture will linger across AZ into western NM with decreasing column moisture with northern extent into NV, UT, and CO. While wetting thunderstorms are probable across the Southwest, PWAT values between 0.5 to 0.75 inches over the Great Basin/central Rockies will support another day of dry thunderstorm potential. Upper ridging over the region will limit broad scale ascent, but orographic lift will be sufficient for isolated thunderstorms. Although current fuel moisture values are sufficiently high to preclude a more robust fire concern, fuel trends will be monitored and may necessitate highlights if they become sufficiently receptive to lightning starts. ...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 1234 PM CDT Thu Aug 10 2023 Valid 111200Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MID AND UPPER MISSISSIPPI AND LOWER MISSOURI VALLEYS... ...SUMMARY... Severe thunderstorms capable of large hail, damaging gusts, and perhaps a tornado or two are possible across portions of the Mid and Upper Mississippi Valley and Lower Missouri Valley areas on Friday. ...Mid and Upper Mississippi/Lower Missouri Valleys... Ongoing thunderstorms -- and some lingering severe potential -- are expected at the start of the period over the southern Wisconsin/eastern Iowa/northwestern Illinois/northern Missouri vicinity. This convection is forecast to continue moving east/southeastward across the central Illinois vicinity through midday. The strongest storms may be capable of producing locally damaging winds and marginal hail. Over southern portions of the SLGT risk area -- i.e. the Mid Mississippi and Lower Missouri Valleys and vicinity -- redevelopment of convection near a roughly west-to-east outflow is expected during the afternoon, and continuing into the evening (aided by southwesterly low-level jet development). With moderate (30 to 40 kt) mid-level northwesterlies, organized/locally severe storms are expected, with locally damaging wind gusts and hail expected. Risk may persist into the overnight hours as storms move southeastward. Farther north, over the Upper Mississippi Valley area, afternoon storm redevelopment is expected, as short-wave mid-level troughing shifts southeastward out of Canada. With daytime heating resulting in ample destabilization, and strong (40 to 50 kt) mid-level northwesterly flow, organized storms capable of producing locally damaging wind gusts and hail are expected to evolve, spreading eastward/southeastward through the evening. Local risk may extend as far east as Lower Michigan into the overnight hours. ...The Southeast... As a weak short-wave trough crosses the Southeast, and a very weak/outflow-reinforced surface front lingers, afternoon heating of the moist boundary layer in place will result in moderate destabilization. This will help to foster redevelopment of storms from the central Gulf Coast states eastward to the southern Atlantic Coast. With moderate lower- to mid-level west-southwesterly flow (around 30 kt), some potential for upscale linear growth/forward propagation is evident, which suggests strong/gusty winds across the area, including a few gusts which may approach severe levels during the afternoon and into the evening hours. ..Goss.. 08/10/2023 Read more

MD 1922 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR THE RED RIVER VALLEY REGION
Mesoscale Discussion 1922 NWS Storm Prediction Center Norman OK 0520 PM CDT Wed Aug 09 2023 Areas affected...The Red River Valley region Concerning...Severe potential...Watch possible Valid 092220Z - 100015Z Probability of Watch Issuance...40 percent SUMMARY...Thunderstorms developing along the Red River Valley will pose a risk for severe winds over the next several hours. Watch issuance is possible. DISCUSSION...Robust convective initiation is underway along a surface trough draped from eastern OK into north/northwest TX. 12 UTC soundings from OUN and FWD sampled high PWAT values generally near 1.75 inches, but recent surface observations are showing high dewpoint depressions on the order of 40-50 F. This suggests that the low-level thermodynamic environment is very deeply mixed and should support accelerating downdrafts. A mix of wet/dry downbursts appear possible with an attendant risk for severe winds. Trends will be monitored, and watch issuance is possible if it becomes evident the severe threat will be sufficiently widespread and persistent. ..Moore/Thompson.. 08/09/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...SHV...TSA...FWD...OUN...SJT... LAT...LON 33159767 32589859 32239920 32089977 32310009 32679983 33419888 33959814 34249771 34629699 34709622 34639533 34019517 33439542 33289645 33159767 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0452 PM CDT Wed Aug 09 2023 Valid 111200Z - 171200Z ...Texas... Extremely dry and warm conditions, with daily highs 100+ F degrees, will continue across central and southern Texas through the extended period. While light rainfall will be possible across portions of southwest/north central Texas, much of central Texas will likely remain dry through D8. High pressure building in across the Four Corners to the Southern Plains will keep winds mostly light, though locally breezy conditions may occur. Elevated to locally Critical fire weather concerns will be likely daily, with low confidence in any one corridor where sustained winds will support Critical risk probabilities. Though the winds will largely stay below criteria, expect continued potential for new fire starts and rapid fire growth in hot and unstable conditions and extremely critically dry fuels. ...Pacific Northwest... Building high pressure will bring warming across the Pacific Northwest. Initial thunderstorm development will be possible as tropical moisture extends northward D4 - Saturday lingering into D7 - Tuesday (detailed below). Beyond the early week thunderstorm activity, thermal troughing may increase. This may lead to increased fire weather concerns in the extended. Confidence is low at this time in placement and strength and as a result impacts. ...Dry Thunderstorms... Potential remnants of tropical storm activity will spread northward into California and southern Oregon beginning D2 - Thursday through D3 - Friday. Recent model runs have been slower and drier with northern extent of the incoming moisture. Initial activity across central/northern California will likely be isolated, with low potential for a dry thunderstorm or two. Potential for thunderstorms will increase into D4 - Saturday and D5 - Sunday as better instability spreads across northern California. A mix of wet/dry storms with gusty and erratic winds may be possible. Confidence in coverage remains too low to include any areas at this time but this will be monitored in the coming days. ..Thornton.. 08/09/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0617 Status Updates
STATUS REPORT ON WW 617 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 45 SSE MKL TO 15 W CHA. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1920 ..WEINMAN..08/09/23 ATTN...WFO...BMX...HUN...MEG...OHX... STATUS REPORT FOR WS 617 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ALC009-019-033-043-049-055-057-059-071-075-077-079-083-089-093- 095-103-127-133-092340- AL . ALABAMA COUNTIES INCLUDED ARE BLOUNT CHEROKEE COLBERT CULLMAN DEKALB ETOWAH FAYETTE FRANKLIN JACKSON LAMAR LAUDERDALE LAWRENCE LIMESTONE MADISON MARION MARSHALL MORGAN WALKER WINSTON MSC003-057-117-141-092340- MS . MISSISSIPPI COUNTIES INCLUDED ARE ALCORN ITAWAMBA PRENTISS TISHOMINGO Read more

WW 617 SEVERE TSTM AL MS TN 091850Z - 100100Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 617 NWS Storm Prediction Center Norman OK 150 PM CDT Wed Aug 9 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northern Alabama Northeast Mississippi Middle Tennessee * Effective this Wednesday afternoon and evening from 150 PM until 800 PM CDT. * Primary threats include... Scattered damaging wind gusts to 65 mph likely Isolated large hail events to 1.5 inches in diameter possible A tornado or two possible SUMMARY...Storms are expected to increase and intensify along a warm front/instability gradient across the region, with wind profiles supportive of a few supercells and bowing segments. The severe thunderstorm watch area is approximately along and 55 statute miles north and south of a line from 40 miles west northwest of Muscle Shoals AL to 50 miles north northeast of Gadsden AL. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU7). 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. && AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 55 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 28025. ...Guyer Read more

WW 0618 Status Updates
STATUS FOR WATCH 0618 HAS NOT BEEN ISSUED YET Read more

WW 618 TORNADO AR KS MO OK 092105Z - 100300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 618 NWS Storm Prediction Center Norman OK 405 PM CDT Wed Aug 9 2023 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Northwest Arkansas Far Southeast Kansas Southwest Missouri Eastern Oklahoma * Effective this Wednesday afternoon and evening from 405 PM until 1000 PM CDT. * Primary threats include... A couple tornadoes possible Scattered damaging wind gusts to 65 mph likely Scattered large hail and isolated very large hail events to 2 inches in diameter possible SUMMARY...The air mass in the wake of storms earlier today continues to gradually destabilize, with severe storms expected to increase mainly near a front through late afternoon and early evening. Strong wind profiles will support initial supercells. The tornado watch area is approximately along and 65 statute miles east and west of a line from 40 miles north northeast of Springfield MO to 30 miles south southeast of Mcalester OK. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU8). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and 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. && OTHER WATCH INFORMATION...CONTINUE...WW 617... AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 55 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 28025. ...Guyer Read more

MD 1921 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF EXTREME EASTERN MONTANA...SOUTHERN NORTH DAKOTA...NORTHERN SOUTH DAKOTA
Mesoscale Discussion 1921 NWS Storm Prediction Center Norman OK 0359 PM CDT Wed Aug 09 2023 Areas affected...portions of extreme eastern Montana...southern North Dakota...northern South Dakota Concerning...Severe potential...Watch unlikely Valid 092059Z - 092330Z Probability of Watch Issuance...5 percent SUMMARY...An instance or two of severe hail or wind may occur later this afternoon into early evening. The severe threat should remain isolated and a WW issuance is not expected. DISCUSSION...Agitated cumulus, along with sparse areas of convective initiation, are underway ahead of a diffuse trailing cold front from extreme eastern MT, eastward along the SD/ND border. Ample heating has mixed the boundary layer, with observed upper 70s/low 80s F temperatures amid low 60s F dewpoints, overspread by 8.5+ C/km boundary-layer lapse rates (20Z mesoanalysis). Given the dry boundary layer, RAP forecast soundings depict the 1000 J/kg MLCAPE (currently in place) distributed in tall/skinny profiles, though unidirectional speed shear is in place. As such, a few multicells or transient supercells may become sustained and support an instance or two of severe hail/wind. Since the severe threat should be sparse, a WW issuance is not expected. ..Squitieri/Guyer.. 08/09/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FGF...ABR...BIS...UNR...BYZ...GGW... LAT...LON 47890494 47620358 46419934 46079728 45589689 45069696 44809822 44880039 45290175 46080364 46640481 47450509 47890494 Read more

MD 1920 CONCERNING SEVERE THUNDERSTORM WATCH 617... FOR PORTIONS OF NORTHERN ALABAMA...SOUTHERN TENNESSEE...NORTHWEST GEORGIA
Mesoscale Discussion 1920 NWS Storm Prediction Center Norman OK 0342 PM CDT Wed Aug 09 2023 Areas affected...Portions of northern Alabama...southern Tennessee... northwest Georgia Concerning...Severe Thunderstorm Watch 617... Valid 092042Z - 092245Z The severe weather threat for Severe Thunderstorm Watch 617 continues. SUMMARY...The primary hazard within WW 617 will remain damaging wind gusts with an organized linear segment along the AL/TN border. A new severe thunderstorm watch may be needed downstream as the airmass destabilizes further. A tornado threat may also be developing along the outflow from this cluster from northeast Mississippi into northern Alabama. DISCUSSION...An organized cluster/linear segment of storms continues east along the Alabama/Tennessee border. With temperatures warming into the mid/upper 80s F in parts of southeastern Tennessee and northwest Georgia, this activity may be able to persist and pose a threat for wind damage into these areas. A downstream severe thunderstorm watch may be needed later this afternoon into parts of southeast Tennessee and northwest Georgia. Along the outflow to the southwest, one storm has initiated in northeast Mississippi with other deepening cumulus in the vicinity. These storms will likely be more discrete and pose a threat for a tornado or two as well as large hail and damaging winds. Convective trends will need to be monitored with this activity to determine if a more substantive tornado threat will develop in the next few hours. ..Wendt.. 08/09/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MRX...FFC...OHX...BMX...HUN...MEG... LAT...LON 34188860 34928766 35218742 35698727 35418465 35168400 34328389 33728433 33688649 33998834 34188860 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Wed Aug 09 2023 Valid 101200Z - 111200Z No changes are needed to the current D2 Fire Weather Outlook risk areas. See previous discussion for more information. Additional information on thunderstorm chances below. ...Mix of Wet/Dry Thunderstorms North Central Texas... High-based scattered thunderstorm activity will be possible across north-central Texas Thursday afternoon. Lightning activity is expected along with gusty outflow winds. Rainfall amounts overall are expected to be brief and light. Additionally, some portion of this region has seen light rain in the last few days. Given the extremely dry fuels, new starts will be possible with locally gusty conditions leading to increased fire behavior. No areas were included at this time as confidence in where dry over wet thunderstorm activity will be is low. ..Thornton.. 08/09/2023 .PREV DISCUSSION... /ISSUED 0152 AM CDT Wed Aug 09 2023/ ...Synopsis... Fire weather concerns will be more limited Thursday compared to previous days with the greatest threat most likely to emerge out of southern to central TX. Elsewhere across the country, localized elevated fire weather conditions may develop across the Snake River Plain in eastern Idaho, as well as the Wyoming Basin in southwest Wyoming, but unreceptive fuels will limit the fire weather threat. ...Texas... As with previous days, hot conditions are forecast again across much of the state with afternoon RH values falling into the 20-30% range. Fuels should remain critically dry despite isolated rain/thunderstorm chances across north TX on Wednesday. However, winds will generally be benign (between 10-15 mph). There is modest probability for sustained winds near 15 mph from the Big Bend region into west central TX in the vicinity of a weak confluence axis. An Elevated risk area is introduced to highlight this corridor where at least 2-3 hours of winds near 15 mph are possible during peak heating. Thunderstorms developing along the boundary by late afternoon will pose a risk of gusty, erratic outflow winds. ...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 0253 PM CDT Wed Aug 09 2023 Valid 092000Z - 101200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERN OKLAHOMA EASTWARD ACROSS THE TENNESSEE VALLEY... ...SUMMARY... Severe thunderstorms capable of producing damaging winds, large hail, and a few tornadoes remain possible from the Ozarks to the Tennessee Valley this afternoon into tonight. ...Discussion... Aside from minor line adjustments -- including a slight southward shift of the risk areas across the Ozarks/Arkansas area and also over northern Lower Michigan -- no appreciable changes appear necessary to the ongoing outlook at this time. ..Goss.. 08/09/2023 .PREV DISCUSSION... /ISSUED 1141 AM CDT Wed Aug 09 2023/ ...Ozarks/Mid-South/Tennessee Valley... Today's severe-weather scenario remains rather complex, largely owing to persistent regenerative precipitation through midday across the Ozarks southwestward into eastern Oklahoma. Short-term guidance appears to be reflecting typical biases/tendencies regarding later-day destabilization, with the 12z NAM likely too aggressive in destabilization (especially with northward extent), with recent RAP runs much more muted buoyancy-wise and southward focused. Regardless of some uncertainties as far as thermodynamic details and meso-beta spatial preferred severe corridors, rather active severe-weather potential still appears likely across the region later today into tonight, especially in deference to seasonally strong wind fields. Initially, ongoing convection across the Mid-South, in vicinity of far eastern Arkansas and western Tennessee at late morning, may intensify and gradually become surface-based this afternoon as it progresses generally eastward across the Tennessee Valley, especially on the southwest flank of these storms in proximity to the warm front. A favorable wind profile, increasing low-level moisture, and the eastern edge of steeper lapse rates aloft (reference 12z observed soundings from Little Rock and Jackson) will support some supercells capable of large hail, along with some tornado potential. Damaging winds will also be possible as activity congeals into clusters across the Tennessee Valley through the afternoon. For additional short-term details (through early afternoon), see Mesoscale Discussion 1914. After a relatively short convective lull (a few hours at most), a secondary round of severe thunderstorms is expected to initiate near/ahead of the surface cold front/inverted trough across parts of central to southern Missouri into eastern Oklahoma during the late afternoon, with outflow/meso-beta zones of differential heating influential as well. As related to the previously discussed thermodynamic uncertainties, the northward-extent (namely across Missouri) of the more intense/higher-coverage severe storms will be highly dependent upon relatively quick/substantive clearing this afternoon. Deep-layer shear vectors will be at least semi-orthogonal to the initiating front and should support initially discrete supercells amid 45-60 kt effective bulk shear. Strengthening low-level southwesterlies during the evening will further enlarge hodograph curvature across southern Missouri and northern Arkansas. This could foster potential for a couple strong tornadoes, but some of this depends on the evolution of the low-level thermodynamic fields in the wake of early day convection. Where storms intensify/mature, upscale growth is likely this evening as low to mid-level flow fields strengthen ahead of the shortwave trough tracking towards the middle Mississippi Valley. This should result in an MCS tracking southeast along the baroclinic zone trailing northwest in the wake of the early-day storms. The spatial extent and amplitude of severe wind gusts will be modulated by cold pools from prior convection and background nocturnal stabilization to some degree. But given 65-80 kt rear-inflow low-level winds depicted in some guidance, there is conditional potential for a more widespread damaging wind threat with embedded significant severe surface gusts and QLCS tornadoes amid bowing structures/mesovortices. ...Upper Midwest from eastern Dakotas to northern Michigan... Thunderstorms are expected to develop/increase by late afternoon along a southward sagging front across a broad west-to-east expanse, likely in a very isolated manner across the Dakotas with a bit more of a concentration (scattered) across eastern Minnesota into northwest/north-central Wisconsin, and possibly northern Michigan. These storms will mature in an environment with only modest buoyancy (MLCAPE between 500-1000 J/kg), but effective shear values between 30-35 kt. Given storm motions and deep-layer shear vectors largely off the front, discrete to semi-discrete storms are probable. Isolated instances of severe hail and wind are possible, mainly late this afternoon through early evening. Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Wed Aug 09 2023 Valid 101200Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CAROLINAS AND SOUTHEASTERN VIRGINIA...AND OVER PORTIONS OF THE NORTHERN PLAINS/MID MISSOURI VALLEY AREA... ...SUMMARY... Strong to severe thunderstorms are possible across parts of the northern Plains, and from the Alabama vicinity to the coastal Carolinas/southeast Virginia on Thursday. ...Synopsis... Within the belt of moderate west-southwesterly mid-level flow across the U.S. Thursday, two short-wave troughs will be associated with two distinct areas of convective/severe potential. The first of these troughs is expected to cross the central and southern Appalachians region during the day, and then should move off the Mid-Atlantic/Carolina Coasts during the evening. Meanwhile, the second trough -- expected over the northern and central High Plains area early in the day --will move east-southeastward across the Plains through the afternoon, and to the Mid and Upper Mississippi Valley region by the end of the period. At the surface, a compact low/frontal system is forecast to cross the central and southern Appalachians region early, and then across Virginia and the Carolinas through the day. The front should clear the East coast from New Jersey southward through late afternoon/early evening, with the low then continuing across southern New England into the overnight hours. Meanwhile, a weaker low/trough is forecast to cross the Plains through the afternoon/evening hours. ...Parts of the Southeast and Mid-Atlantic regions... Thunderstorms -- possibly in the form of an at least loosely organized band -- will likely be ongoing at the start of the period across the western Carolinas vicinity. These storms may be accompanied by ongoing risk for locally damaging wind gusts, and possibly a tornado. Some decrease in intensity may occur with this convection into the afternoon, though indications are that subsequent storm redevelopment may occur across the southeastern Virginia/eastern Carolinas area during the afternoon, ahead of the advancing cold front. These storms would also likely pose a risk for damaging winds locally, along with potential for hail and a tornado or two before storms move offshore during the evening. ...Northern Plains and Mid-Missouri Valley area... Diurnal heating ahead of an advancing/weak cool front will result in moderate afternoon warm-sector destabilization across the central and northern Plains region. As the boundary advances in tandem with weak upper short-wave troughing, isolated to widely scattered storm development is expected by latter stages of the afternoon period. CAM output from various models differs, with respect to storm coverage, though several suggest upscale/linear growth with time, and possibly even an eventual southeastward-moving, bowing MCS across the Mid-Missouri Valley area during the evening and possibly into the overnight hours. In any case, with 35 to 45 kt mid-level west-northwesterlies across the area, atop low-level southerly warm-sector winds, shear will support potential for organized storms, and attendant risks for locally damaging wind gusts, and severe-caliber hail. A tornado cannot be ruled out, mainly across the eastern South Dakota vicinity where slightly backed low-level flow is anticipated ahead of the weak surface low. While storm coverage remains uncertain, current indications are that upgrade to SLGT risk is warranted for the afternoon and evening hours. ...Southern New England... As a deepening surface low crosses southern New England during the second half of Thursday, meager CAPE may support a few thunderstorms. Within the northeast quadrant of the low -- across southeastern New England -- a very favorable flow field is anticipated, with low-level winds veering/increasing rapidly with height. While the thermodynamic deficiency that is anticipated should substantially limit overall potential, conditional risk for a couple of stronger wind gusts and/or a tornado or two is evident, mainly from late afternoon through late evening, until the low and associated front sweep northeastward/offshore. ..Goss.. 08/09/2023 Read more

No Mesoscale Discussions are in effect as of Tue Aug 8 22:16:12 UTC 2023.

WW 0614 Status Updates
STATUS REPORT ON WW 614 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..WEINMAN..08/08/23 ATTN...WFO...BOU...GLD...LBF...CYS... STATUS REPORT FOR WS 614 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC001-005-017-039-063-073-075-087-095-115-121-123-125-082240- CO . COLORADO COUNTIES INCLUDED ARE ADAMS ARAPAHOE CHEYENNE ELBERT KIT CARSON LINCOLN LOGAN MORGAN PHILLIPS SEDGWICK WASHINGTON WELD YUMA KSC023-153-181-193-199-082240- KS . KANSAS COUNTIES INCLUDED ARE CHEYENNE RAWLINS SHERMAN THOMAS WALLACE NEC005-007-013-029-031-033-045-049-057-069-075-085-087-091-101- 105-111-113-117-123-135-157-161-165-171-082240- NE . NEBRASKA COUNTIES INCLUDED ARE Read more

WW 614 SEVERE TSTM CO KS NE WY 082035Z - 090400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 614 NWS Storm Prediction Center Norman OK 235 PM MDT Tue Aug 8 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northeast Colorado Northwest Kansas Western Nebraska Southeast Wyoming * Effective this Tuesday afternoon and evening from 235 PM until 1000 PM MDT. * Primary threats include... Scattered large hail likely with isolated very large hail events to 3.5 inches in diameter possible Scattered damaging winds and isolated significant gusts to 75 mph possible A tornado or two possible SUMMARY...Widely scattered severe storms will develop through late afternoon/early evening across the region, including supercells capable of very large hail and some tornado risk, especially with the storms across far northeast Colorado/far northwest Kansas/far southwest Nebraska. Storms will gradually cluster by early evening with an increased potential for damaging winds, some of them capable of significantly strong and destructive winds. The severe thunderstorm watch area is approximately along and 135 statute miles north and south of a line from 70 miles south southwest of Torrington WY to 45 miles northeast of Imperial NE. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU4). 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 613... AVIATION...A few severe thunderstorms with hail surface and aloft to 3.5 inches. Extreme turbulence and surface wind gusts to 65 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 28025. ...Guyer Read more

WW 0613 Status Updates
STATUS REPORT ON WW 613 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 10 ENE CEW TO 20 S DHN TO 15 WNW ABY TO 25 NW MCN. ..WEINMAN..08/08/23 ATTN...WFO...BMX...TAE...FFC... STATUS REPORT FOR WS 613 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ALC069-082240- AL . ALABAMA COUNTIES INCLUDED ARE HOUSTON FLC059-063-131-133-082240- FL . FLORIDA COUNTIES INCLUDED ARE HOLMES JACKSON WALTON WASHINGTON GAC007-017-019-021-023-027-071-075-079-081-087-091-093-095-099- 131-153-155-173-177-185-193-201-205-225-235-253-261-271-275-277- 287-289-315-321-082240- GA . GEORGIA COUNTIES INCLUDED ARE BAKER BEN HILL BERRIEN Read more

WW 613 SEVERE TSTM AL FL GA 081905Z - 090100Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 613 NWS Storm Prediction Center Norman OK 305 PM EDT Tue Aug 8 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southeast Alabama Florida Panhandle Southern Georgia * Effective this Tuesday afternoon and evening from 305 PM until 900 PM EDT. * Primary threats include... Scattered damaging wind gusts to 65 mph possible SUMMARY...Within a hot/very moist air mass, storms should continue to intensify across the region as they move eastward, including the potential development of some semi-organized clusters capable of wind damage. The severe thunderstorm watch area is approximately along and 65 statute miles north and south of a line from 15 miles south of Troy AL to 60 miles northeast of Moultrie GA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU3). 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. && AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 55 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 26025. ...Guyer Read more