Severe Storms

WW 0689 Status Updates
STATUS REPORT ON WW 689 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 2176 ..MOORE..09/22/23 ATTN...WFO...CYS...LBF...UNR... STATUS REPORT FOR WS 689 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NEC007-013-033-045-069-105-123-157-161-165-222340- NE . NEBRASKA COUNTIES INCLUDED ARE BANNER BOX BUTTE CHEYENNE DAWES GARDEN KIMBALL MORRILL SCOTTS BLUFF SHERIDAN SIOUX SDC033-047-102-222340- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE CUSTER FALL RIVER OGLALA LAKOTA WYC005-009-011-015-027-045-222340- WY . WYOMING COUNTIES INCLUDED ARE Read more

WW 689 SEVERE TSTM NE SD WY 221935Z - 230300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 689 NWS Storm Prediction Center Norman OK 135 PM MDT Fri Sep 22 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Western Nebraska Southwest South Dakota Eastern Wyoming * Effective this Friday afternoon and evening from 135 PM until 900 PM MDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2.5 inches in diameter possible Isolated damaging wind gusts to 70 mph possible A tornado or two possible SUMMARY...Isolated severe thunderstorms including some supercells are expected to develop through mid/late afternoon and spread east-northeastward across the region through early evening. The severe thunderstorm watch area is approximately along and 70 statute miles east and west of a line from 35 miles east northeast of Gillette WY to 55 miles south southeast of Scottsbluff NE. 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. && AVIATION...A few severe thunderstorms with hail surface and aloft to 2.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 450. Mean storm motion vector 24025. ...Guyer Read more

WW 689 SEVERE TSTM NE SD WY 221935Z - 230300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 689 NWS Storm Prediction Center Norman OK 135 PM MDT Fri Sep 22 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Western Nebraska Southwest South Dakota Eastern Wyoming * Effective this Friday afternoon and evening from 135 PM until 900 PM MDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2.5 inches in diameter possible Isolated damaging wind gusts to 70 mph possible A tornado or two possible SUMMARY...Isolated severe thunderstorms including some supercells are expected to develop through mid/late afternoon and spread east-northeastward across the region through early evening. The severe thunderstorm watch area is approximately along and 70 statute miles east and west of a line from 35 miles east northeast of Gillette WY to 55 miles south southeast of Scottsbluff NE. 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. && AVIATION...A few severe thunderstorms with hail surface and aloft to 2.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 450. Mean storm motion vector 24025. ...Guyer Read more

MD 2176 CONCERNING SEVERE THUNDERSTORM WATCH 689... FOR SOUTHEAST WYOMING INTO THE NEBRASKA PANHANDLE
Mesoscale Discussion 2176 NWS Storm Prediction Center Norman OK 0526 PM CDT Fri Sep 22 2023 Areas affected...Southeast Wyoming into the Nebraska Panhandle Concerning...Severe Thunderstorm Watch 689... Valid 222226Z - 230030Z The severe weather threat for Severe Thunderstorm Watch 689 continues. SUMMARY...The severe risk continues across WW 689, with the greatest near-term severe risk downstream of a supercell across the northwestern Nebraska Panhandle and perhaps across far the far southwestern Nebraska Panhandle. Large to very large hail will be the primary threat. DISCUSSION...Over the past hour, a pair of supercells have matured across the NE Panhandle with multiple reports of 1-2.5 inch hail. Elongated hodographs across the region remain very favorable for supercell maintenance with effective bulk shear values upwards of 50 knots. However, the recent demise of the supercell over the southern NE Panhandle, coupled with several failed attempts at additional convective initiation over southeast WY, hints that thermodynamics are a modulating factor in this environment. The expectation over the next 1-2 hours is for the greatest severe risk to reside downstream of the supercell over the northwestern NE Panhandle where ascent along a subtle surface confluence axis will likely compensate for diminishing downstream buoyancy. Given the favorable wind profiles and steep mid-level lapse rates, large to very large hail should be the primary concern. Elsewhere across WW 689, signs of upstream ascent in regional reflectivity trends, persistent agitated cumulus clusters, and several recent attempts at convective initiation all suggest that additional storm development is possible. Recent GOES imagery shows the deepest cumulus/ the most robust CI attempts are occurring across far southeast WY and the far southwestern NE Panhandle where low-level convergence is regionally maximized. Hence, the severe threat may be locally higher downstream of this cumulus cluster over the next 1-2 hours if a supercell can become established. However, the probability of surface-based CI occurring may begin to wane beyond the next couple of hours with the onset of nocturnal cooling shortly after sunset. ..Moore.. 09/22/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...UNR...BOU...CYS... LAT...LON 40790253 40840345 41530460 42710525 43290581 43580570 43660540 43110386 42400273 41800228 41440210 41010213 40840228 40790253 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0402 PM CDT Fri Sep 22 2023 Valid 241200Z - 301200Z Shortwave ridging over the western US will quickly breakdown ahead of a Pacific trough moving onshore late this weekend into early next week. As the upper ridge breaks down and strong flow aloft moves overhead, localized dry and breezy conditions are possible across parts of the Northwest, Great Basin, and Rockies. By mid week next week, rain chances are forecast to increase limiting fire-weather concerns over much of the Northwest. Some fire concerns may linger over the Great Basin and Rockies, but confidence is low. ...Northern Great Basin and Rockies... Early next week, enhanced mid-level flow associated with the Pacific trough will begin to overspread much of the western CONUS including the Great Basin and northern Rockies. While temperatures and humidity are not expected to be overly warm/dry, the increase in southwesterly flow aloft may support localized pockets of dry and breezy conditions (winds 15-20 mph and RH below 25%) as early as D3/Sunday, continuing trough midweek. Fuels across much of the region have not been overly favorable for fire spread in recent weeks from precipitation and cooler temperatures. Further uncertainty exists regarding the chance for additional precipitation with the trough as it continues to move eastward through the week. However, the introduction of gusty winds may allow for some drying of fine fuels enough to support a low chance for fire-weather conditions through the forecast period. Ensemble and deterministic guidance suggest the most likely corridors for low-end fire-weather conditions will exist across portions of northern CA/NV into southern ID, and across parts of the Rockies in northern CO/southern WY, and western MT. However, with the uncertainties regarding fuel availability and precipitation chances, confidence in sustained critical fire-weather conditions is low. Towards the end of the extended forecast period, model guidance diverges on the overall amplification of the upper-level flow pattern and the subsequent risk for critical fire-weather conditions. Some indications for a return to strong ridging may favor a slow increase in fire-weather concerns late in the month. Conversely, a cut-off low or persistent troughing, as indicated by some ensemble guidance, may also allow for cooler and wetter conditions across the western US into October. ..Lyons.. 09/22/2023 ...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 Fri Sep 22 2023 Valid 222000Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS...AND THE COASTAL MID-ATLANTIC... ...SUMMARY... Severe thunderstorms are possible across parts of the north-central High Plains this afternoon and this evening. A few tornadoes are also possible over the coastal southern Mid-Atlantic/Tidewater region overnight into tomorrow morning. ...20Z Update... ...North-Central High Plains... As mentioned in recently issued MCD #2174, the severe-thunderstorm threat is expected to increase with time across the region this afternoon. Wind profiles will become increasingly favorable for organized storms, and a couple of supercells may evolve with time. Steep midlevel lapse rates and cool temperatures aloft will support large hail of 1.5 to 2 inches in diameter, conditional on supercell development. A tornado or two will also be possible if multiple sustained supercells can develop and mature. Severe Thunderstorm Watch #689 was recently issued to cover the potential risk across the region. ...Coastal southern Mid-Atlantic/Tidewater... No significant changes have been made by NHC to the forecast track of Tropical Storm Ophelia, with the system still expected to be onshore over the central NC coast by 12Z tomorrow. Stable conditions are in place across this region now, but an increasingly moist and buoyant boundary layer is expected to advect into the region overnight. This could support a few stronger convective cores, which, given the strong low-level wind fields, could then produce brief tornadoes. ..Mosier.. 09/22/2023 .PREV DISCUSSION... /ISSUED 1134 AM CDT Fri Sep 22 2023/ ...North-central High Plains... Scattered thunderstorms are still ongoing at midday across western portions of Nebraska/South Dakota, generally in association with a lead shortwave trough downstream of a more prominent upper trough over the northern Intermountain region. In this wake of this activity, the primary corridor of diurnal destabilization will be focused in a northwest/southeast-oriented corridor across eastern Wyoming into the Nebraska Panhandle and extreme southwest South Dakota. Aided by low-level upslope flow/differential heating and the approach of the upstream trough/speed max, the aforementioned corridor is where at least isolated severe storms are expected to develop into mid/late afternoon, and subsequently move through this relatively narrow corridor of modest instability (MLCAPE 750-1250 J/kg). Long hodographs with 40+ kt effective shear will support supercells capable of large hail (locally significant 2+ inch), and possibly some tornado risk given the relatively moist environment. These storms should spread east-northeastward across much of the north-central Plains tonight, with the potential for large hail and locally damaging winds continuing possibly into the overnight. ...Coastal southern Mid-Atlantic/Tidewater... The potential for supercells and a few tornadoes is expected to increase late tonight as Potential Tropical Cyclone 16 approaches the coast. Reference the National Hurricane Center for the latest track/intensity forecast details. While inland areas are currently stable with respect to surface-based convection, higher theta-e air will accompany a warm front shifting toward the coast late tonight, all while low/mid-level winds strengthen on the northern periphery of the Potential Tropical Cyclone. Supercell-favorable ingredients are expected to be maximized across coastal eastern North Carolina into far southeast Virginia. This is where MLCAPE in the 500-1500 J/kg range is possible, despite midlevel lapse rates only slightly greater than moist adiabatic. Enlarging and well-curved hodographs are expected, with effective SRH of 300-500 m2/s2. A few tornadoes are possible mainly during the overnight into early Saturday. ...Iowa... An MCV continues to drift east-northeastward across western Iowa at midday. While plentiful cloud cover and some showers/thunderstorms precede the MCV, modest destabilization should gradually occur mainly across eastern Iowa this afternoon. Some stronger to locally severe storms could develop accordingly, aided by influences of the MCV. ...Eastern Oklahoma/ArkLaTex... While a few stronger storms could occur today, severe potential is expected to remain very limited across the region as warm advection abates and mid-level lapse rates remain modest. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0241 PM CDT Fri Sep 22 2023 Valid 231200Z - 241200Z ...NO CRITICAL AREAS... ...20z Update... No changes will be made to the current outlook. Overall fire-weather concerns are expected to remain below Elevated criteria and localized across the lee of the Rockies and northern Great Basin. See the previous discussions for more information. ..Lyons.. 09/22/2023 .PREV DISCUSSION... /ISSUED 0130 AM CDT Fri Sep 22 2023/ ...Synopsis... Fire weather concerns should remain fairly localized for Saturday along the High Plains. A surface low and an attendant surface trough are forecast to deepen as they migrate east across the Plains on Saturday. This will establish a zonal flow regime across much of the Rockies and High Plains by late morning. Downslope warming/drying along the CO Front Range and in the lee of the Sangre de Cristo and Sandia/Manzano Mountains, augmented by diurnal heating, should promote areas of 15-25% RH as winds increase to 15-20 mph (with locally drier/windier in terrain-favored locations). Somewhat meager mid to upper-level winds should confine the strongest surface winds close to terrain features - with the exception of southeast WY into adjacent portions of NE/northeast CO where surface gradient winds will be stronger. This, combined with somewhat marginal fuel status outside of far northeast NM and southern CO, will limit the coverage of elevated conditions and the overall fire weather threat. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0688 Status Updates
STATUS REPORT ON WW 688 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..LYONS..09/21/23 ATTN...WFO...GID... STATUS REPORT FOR WT 688 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS KSC089-123-141-183-220040- KS . KANSAS COUNTIES INCLUDED ARE JEWELL MITCHELL OSBORNE SMITH NEC001-019-035-061-079-099-129-181-220040- NE . NEBRASKA COUNTIES INCLUDED ARE ADAMS BUFFALO CLAY FRANKLIN HALL KEARNEY NUCKOLLS WEBSTER 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 688 TORNADO KS NE 212150Z - 220300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 688 NWS Storm Prediction Center Norman OK 450 PM CDT Thu Sep 21 2023 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of North central Kansas South central Nebraska * Effective this Thursday afternoon and evening from 450 PM until 1000 PM CDT. * Primary threats include... A couple tornadoes possible Scattered large hail and isolated very large hail events to 2.5 inches in diameter possible Scattered damaging wind gusts to 70 mph possible SUMMARY...Supercells will persist into this evening along a stationary front across southern Nebraska, with the potential to produce a couple of tornadoes and isolated very large hail of 2 to 2.5 inches in diameter. Some clustering of storms is expected later this evening into early tonight, with some increase in the threat for damaging winds as storms spread east-southeastward along the Nebraska/Kansas border. The tornado watch area is approximately along and 35 statute miles east and west of a line from 25 miles north of Kearney NE to 90 miles south of Hastings NE. 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 687... AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 2.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 26010. ...Thompson Read more

WW 0687 Status Updates
STATUS REPORT ON WW 687 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..LYONS..09/21/23 ATTN...WFO...GLD...GID...LBF... STATUS REPORT FOR WT 687 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS KSC039-063-065-109-137-147-153-163-179-193-220040- KS . KANSAS COUNTIES INCLUDED ARE DECATUR GOVE GRAHAM LOGAN NORTON PHILLIPS RAWLINS ROOKS SHERIDAN THOMAS NEC005-029-041-047-049-063-065-069-073-075-083-085-087-091-101- 111-113-117-135-137-145-171-220040- NE . NEBRASKA COUNTIES INCLUDED ARE ARTHUR CHASE CUSTER DAWSON DEUEL FRONTIER FURNAS GARDEN GOSPER GRANT HARLAN HAYES HITCHCOCK HOOKER KEITH LINCOLN LOGAN MCPHERSON PERKINS PHELPS RED WILLOW THOMAS Read more

WW 687 TORNADO KS NE 211950Z - 220300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 687 NWS Storm Prediction Center Norman OK 250 PM CDT Thu Sep 21 2023 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Northwest Kansas Southwest Nebraska * Effective this Thursday afternoon and evening from 250 PM until 1000 PM CDT. * Primary threats include... A few tornadoes possible Scattered large hail likely with isolated very large hail events to 3 inches in diameter possible Scattered damaging wind gusts to 70 mph possible SUMMARY...Thunderstorms are expected to rapidly develop this afternoon along a dryline and warm front lying across the area. Supercells capable of very large hail and a few tornadoes are expected. The tornado watch area is approximately along and 60 statute miles east and west of a line from 35 miles south southwest of Hill City KS to 60 miles north northwest of North Platte NE. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU7). 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. && AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 3 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 28025. ...Hart Read more

MD 2172 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EASTERN KANSAS INTO FAR NORTHEAST OKLAHOMA
Mesoscale Discussion 2172 NWS Storm Prediction Center Norman OK 0518 PM CDT Thu Sep 21 2023 Areas affected...Eastern Kansas into far northeast Oklahoma Concerning...Severe potential...Watch unlikely Valid 212218Z - 220015Z Probability of Watch Issuance...20 percent SUMMARY...A few strong to severe storms appear probable this evening with an attendant risk for damaging winds and large hail. However, this risk should remain sufficiently isolated to preclude watch issuance. DISCUSSION...Over the past hour, isolated thunderstorms have initiated across eastern KS with somewhat rapid cloud top cooling noted in IR imagery (approximately 20 C over a 20 minute window). Broken cloud cover through the afternoon has muted diurnal destabilization to some degree, but seasonally rich low-level moisture (mid 60s dewpoints) is supporting MLCAPE values upwards of 2000 J/kg. Additionally, southeasterly low-level flow under southwesterly winds aloft is supporting effective bulk shear values near 35 knots - sufficiently for organized cells. Although the regional environment is supportive of supercells with an attendant hail/wind risk, east/southeast KS is on the periphery of stronger mesoscale and synoptic ascent to the northwest across northern KS and NE. This casts uncertainty onto storm coverage, and slow storm motions should limit the potential for storm interactions/upscale growth. Consequently, this threat should remain fairly isolated, and a watch will likely not be needed. ..Moore/Thompson.. 09/21/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...SGF...EAX...TSA...TOP...ICT... LAT...LON 37089605 37569650 38159697 38739706 38929702 39139669 39079624 38679546 38159501 37569460 37149449 36759460 36649505 36709542 37089605 Read more

MD 2171 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EASTERN NEW MEXICO INTO THE OKLAHOMA AND TEXAS PANHANDLES
Mesoscale Discussion 2171 NWS Storm Prediction Center Norman OK 0443 PM CDT Thu Sep 21 2023 Areas affected...Eastern New Mexico into the Oklahoma and Texas Panhandles Concerning...Severe potential...Watch unlikely Valid 212143Z - 212345Z Probability of Watch Issuance...20 percent SUMMARY...Thunderstorms will increase in coverage over the next few hours, and a few strong to severe storms appear likely. Severe wind and large hail will be the primary threats, but confidence in the coverage/duration of this threat is limited and watch issuance is not anticipated. DISCUSSION...Convective initiation is well underway across central to eastern NM within the left-exit region of an approaching upper jet. This high-based activity is developing on the western fringe of the low-level moisture plume over the Plains with dewpoints in the upper 40s to low 50s and dewpoint depressions upwards of 40-50 F noted in latest surface obs. Although buoyancy profiles are somewhat meager (MLCAPE between 500-1000 J/kg), the deeply-mixed low-level thermodynamic profile is conducive for strong to severe downburst winds. Combined with weak low-level flow, this may favor undercutting outflows and storm clustering with time, which limits confidence in the duration of any particular strong/severe storm. However, strong speed shear in the 0-6 km layer will support initial cell organization with an attendant hail risk. The expectation over the next several hours is for additional storms to develop across eastern NM, slowly intensifying (with perhaps some clustering/upscale growth) as they migrate into the TX/OK Panhandles where low-level moisture improves. However, increasing inhibition closer to the TX/western OK border and the onset of nocturnal cooling later this evening may limit the eastward extent of the threat. ..Moore/Thompson.. 09/21/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DDC...LUB...AMA...MAF...PUB...ABQ...EPZ... LAT...LON 33500539 33750532 36570391 36760369 37300238 37370157 37160094 36540052 35430051 34140145 33480266 33120417 33040464 33020500 33100523 33300532 33500539 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0359 PM CDT Thu Sep 21 2023 Valid 231200Z - 291200Z ...Day 3/Saturday... On the backside of a midlevel low tracking northeastward across the northern Plains, strong deep-layer northwesterly flow will overspread the northern/central High Plains. As a result, 25+ mph sustained west-northwesterly surface winds (with higher gusts) are expected across portions of southern WY, western NE, and far northeastern CO. While these winds could briefly overlap 20-30 percent RH over the area, marginal fuels should generally limit the fire-weather risk. ...Days 4-5/Sunday-Monday... Southwesterly midlevel flow will gradually strengthen across the Northwest on Days 4-5/Sunday-Monday, favoring breezy southwesterly surface winds across portions of northeastern CA, northwestern NV, and far southeastern OR -- where 15-20 percent RH is possible. With that said, fuels are generally unsupportive of large fires over these areas -- precluding Critical probabilities. ...Days 6-8/Tuesday-Thursday... The potential for dry/breezy conditions should focus over portions of the Southwest and Great Basin late in the extended forecast period, and potentially over the High Plains depending on moisture return. However, additional rainfall over already marginal fuels across these areas cast uncertainty on the fire-weather risk. ..Weinman.. 09/21/2023 ...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 0249 PM CDT Thu Sep 21 2023 Valid 212000Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF WESTERN KS AND WESTERN/CENTRAL NE...AND OVER PARTS OF SOUTHERN OK AND NORTH TX... ...SUMMARY... Widely scattered strong to severe thunderstorms are possible this afternoon into tonight across parts of the southern and central Plains. ...20Z Update... ...NE/KS... Recent surface analysis places a low near the CO/NE/KS border intersection, with a dryline extending southward across western KS. As mentioned in recently issued MCD #2168, storm initiation appears probable in the next couple of hours across parts of southwestern Nebraska. The deepening surface low is supporting robust southeasterly flow and strong low-level shear. Moderate westerly flow exists atop this low-level southeasterly flow, supporting 30 to 40 kt of effective bulk shear. Strong buoyancy has also developed ahead of the dryline, with recent mesoanalysis estimating 1500 to 2500 J/kg MLCAPE across western KS and western/central NE. The overall environment supports supercells capable of all severe hazards including large to very-large (1-3 in.) hail, severe wind gusts (60-70 mph), and tornadoes. The tornado threat will generally be maximized near the warm front where surface winds remain more backed. ...Southern OK/North TX... Despite widespread clouds, temperatures have reached the upper 80s/low 90s across much of the region. Dewpoints are in the upper 60s/low 70s, and this combination of temperatures and dewpoints is supporting strong buoyancy. Recent mesoanalysis estimates MLCAPE is around 2000-2500 J/kg. Vertical shear is modest, but sufficient for some updraft organization. As such, a few strong to severe thunderstorms remain possible, with large hail and damaging gusts as the primary threats. ..Mosier.. 09/21/2023 .PREV DISCUSSION... /ISSUED 1112 AM CDT Thu Sep 21 2023/ ...Central and Southern Plains... Morning water vapor imagery shows a subtle shortwave trough crossing the Rockies of central CO. This feature will move eastward and provide weak large scale ascent across much of the central Plains this afternoon and evening. Morning model solutions are diverse in placement/timing of thunderstorm activity, but generally show a larger envelope of potential risk. Therefore have expanded the MRGL to include much more of the central and southern Plains. ...NE/KS... A rather pronounced surface dryline is expected to develop later today from western NE southward into western KS, with dewpoints in the 60s and MLCAPE values of over 2500 J/kg to the east of the boundary. Given the weak forcing and some cap, the areal coverage of convective initiation is uncertain. However, any storm that forms along this axis will have a conditional threat of very large hail and a tornado or two. These storms may persist for several hours after dark and track eastward into parts of north central KS and central NE. ...OK/TX... A weak sub-tropical shortwave trough is moving into west TX. Lift ahead of this feature is resulting in a large region of accas and a few showers and thunderstorms moving into southwest OK/northwest TX. Continued daytime heating is expected to lead to convective intensification by late afternoon across north TX and southern OK. The strongest cells in this area may produce hail and gusty winds for a few hours into this evening. ...Eastern NC... The outer bands of the strengthening tropical system off the southeast Atlantic coast are forecast to still be well offshore by Fri/12z. Therefore will defer any increasing tornado risk to the Day2 period. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0207 PM CDT Thu Sep 21 2023 Valid 221200Z - 231200Z The latest fuels information suggests that fine fuels have dried sufficiently over portions of the mountains/I-25 corridor in southern Colorado to support some fire potential. Given the expectation for sustained southwesterly surface winds of 15-25 mph (with higher gusts) and around 10 percent RH, the Elevated highlights were expanded westward into this area. Over the southeast Colorado plains, the Elevated highlights were trimmed as the latest guidance suggests sustained surface winds will be too weak for an appreciable fire-weather risk. For additional details, see the previous discussion below. ..Weinman.. 09/21/2023 .PREV DISCUSSION... /ISSUED 0157 AM CDT Thu Sep 21 2023/ ...Synopsis... An upper low across eastern Oregon will start to fill during the day Friday and eventually become a negatively tilted open wave across the central/northern Rockies. As this upper-level pattern evolves, lee troughing is expected, which will bring some breezy conditions from the Southwest into the central Rockies and also the central High Plains and the central Plains. Farther west in Arizona and Utah, fuels are too moist to support fire spread. However, in the plains across southeast Colorado and northeast New Mexico and vicinity, some drier fuels are present. These fuels will likely dry further with single-digit relative humidity. Therefore, an Elevated area has been added for portions of the central High Plains for Friday. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook AMEND 1 NWS Storm Prediction Center Norman OK 0127 PM CDT Thu Sep 21 2023 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL/SOUTHERN PLAINS INTO PARTS OF MO/IA/SOUTHERN MN... AMENDED TO ADD SEVERE PROBABILITIES OVER THE COASTAL MID-ATLANTIC ...SUMMARY... Severe thunderstorms are possible on Saturday across parts of the central and southern Plains into Iowa and Missouri. ...Coastal Mid-Atlantic... Recently issued track of Potential Tropical Cyclone 16 brings it onshore over coastal NC early Saturday morning, and then northward into the Chesapeake Bay by Saturday evening. Recent guidance suggests the warm sector to the north and east of the system's center should penetrate far enough inland to support modest buoyancy and deeper convective cores. Given the strong low to mid-level wind fields, any updrafts that are able to deepen and mature could produce tornadoes. Mesoscale details, in particular how much buoyancy develops inland, remain uncertain enough to introducing only a Marginal/Level 2 risk with this amendment. -- PREVIOUS DISCUSSION -- ...Great Plains into parts of MN/IA/MO... A seasonably strong mid/upper-level cyclone is forecast to move eastward across SD on Saturday. The primary surface low attendant to this mid/upper cyclone is forecast to move from the central Plains into the Dakotas as the system begins to occlude, while secondary surface low development is possible along the trailing front across the southern Plains. Moderate to locally strong buoyancy is expected to develop across a broad area of the Great Plains on Saturday, east of the cold front and outside of any areas where outflow persists from morning convection. One notable midlevel jet maximum is forecast to move from the central Plains into the Dakotas, while a southern-stream jet maximum will begin to impinge upon parts of the southern Plains. Organized convection will be possible Saturday into Saturday night across a broad region from the Great Plains into parts of MN/IA/MO, with a mixture of supercells and organized clusters possible along/east of a cold front. Initial development is most likely closer to the mid/upper-level low across the central/northern Plains, with storm development into parts of the southern Plains expected by early Saturday evening. All severe hazards will be possible, though primary storm mode and evolution of mesoscale details remain uncertain at this forecast range. ...Eastern NC into the Mid Atlantic... A surface low is forecast to move from near or just offshore of eastern NC into parts of the Mid Atlantic on Saturday. Depending on the westward extent of the track, richer low-level moisture may spread into coastal areas of the Mid Atlantic region, potentially accompanied by increasing low-level flow/shear and some threat for a brief tornado or two. Depending on the ultimate track and intensity of this system, severe probabilities may eventually be needed for some part of this region. ..Mosier/Dean.. 09/21/2023 Read more

No watches are valid as of Wed Sep 20 22:31:02 UTC 2023.

No Mesoscale Discussions are in effect as of Wed Sep 20 22:31:02 UTC 2023.

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0324 PM CDT Wed Sep 20 2023 Valid 221200Z - 281200Z ...Day 3/Friday... A strong westerly mid/upper-level jet streak, accompanying a deep midlevel low tracking eastward across the northern Rockies, will impinge on the central Rockies and adjacent High Plains on Day 3/Friday. A related surface low will deepen over the KS/CO border, yielding a tightening surface pressure gradient across the region. Downslope warming/drying (10-15 percent RH) over northeast NM, the western TX/OK Panhandles, and southeastern CO, combined with breezy/gusty westerly surface winds, will support elevated to locally critical fire-weather conditions. The primary limiting factor is marginal fuels across the area, precluding 70-percent Critical probabilities. Beyond Day 3/Friday, the potential for critical meteorological conditions over dry fuels appears low. ..Weinman.. 09/20/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more