Severe Storms

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0449 PM CDT Sat Aug 26 2023 Valid 281200Z - 031200Z ...D3/Mon - D5/Wed - Southern Plains... Dry and breezy post-frontal flow in the southern Plains will lead to an extended period of elevated to potentially critical fire weather conditions in a region with ongoing extreme to exceptional drought. Thunderstorms today and Sunday may improve fuel state in some localized regions, but it is not expected to be widespread enough to have a significant impact on fuel receptiveness. ...D3/Mon - D5/Wed - Northwest... A negatively tilted mid-level trough will start to proceed inland across the Pacific Northwest on Monday. As this occurs, some thunderstorms will be possible across the Cascade crests during the day and much of western Washington overnight. PWAT values are expected to be around 1 inch with storms likely more wet. However, storm speeds will be in excess of 30 mph, which could increase the threat for dry thunderstorms somewhat. As this trough advances east, some breezy conditions are expected in the higher terrain on the western slopes of the Cascades and through the Cascade gaps. The significant moisture surge with this system may keep relative humidity higher and thus keep the fire weather threat somewhat more subdued than otherwise may be expected. These dry and breezy conditions will expand into the Great Basin and Columbia Basin on Tuesday and Wednesday. At this time, no 40 percent probabilities have been added as relative humidity is forecast to stay 30%+ where fuel are critically dry. ...D4/Tue - D5/Wed - Montana... There will be some potential for critical fire weather conditions on Tuesday on Wednesday across portions of northern Montana both ahead and behind the surface front. Fuels had moistened recently in the area but are starting to dry once again. If fuels continue to dry and winds/relative humidity continue to show worsening conditions, a 40% probability may be needed in later outlooks. ..Bentley.. 08/26/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 2056 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF EASTERN OREGON AND SOUTH CENTRAL IDAHO
Mesoscale Discussion 2056 NWS Storm Prediction Center Norman OK 0332 PM CDT Sat Aug 26 2023 Areas affected...portions of eastern Oregon and south central Idaho Concerning...Severe potential...Watch unlikely Valid 262032Z - 262230Z Probability of Watch Issuance...20 percent SUMMARY...Isolated high-based strong to severe storms are possible this afternoon and evening. Damaging gusts and small hail are possible with the strongest storms. A WW is unlikely. DISCUSSION...Across the northern Intermountain west, broad southerly flow ahead of a mid-level trough was transporting monsoon moisture northward into portions of eastern OR and southern ID. At the nose of this surge, visible imagery showed new thunderstorm development ongoing across parts of far northern NV/UT into southern ID. Clear skies have allowed for strong diurnal heating and destabilization with MUCAPE of 1000-15000 J/kg observed via SPC mesoanalysis. As remaining inhibition is removed ahead of the northward lifting trough, thunderstorms should continue to develop and mature through the afternoon. Vertical shear of 30-35 kt should support some storm organization/longevity into organized multicells and perhaps transient supercell structures. Likely high based with LCLs near or exceeding 2500 m, the primary risk will be damaging outflow gusts from the more persistent storms. However, some small accumulating hail may also be possible given relatively steep mid-level lapse rates and the presence of a few longer-lived, and stronger updrafts. The primary uncertainty with regard to the severe threat this afternoon/evening is the coverage of severe storms. While a few stronger updrafts are likely to evolve, broader synoptic forcing for ascent is still relatively modest. This suggests a generally more isolated threat related to individual storm evolution through much of the day. Given this uncertainty, a new WW appears unlikely, but convective trends will be monitored. ..Lyons/Thompson.. 08/26/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PIH...MSO...BOI...PDT... LAT...LON 44541421 43601328 43111328 42791353 42581434 42551518 42791597 43481753 43911823 44211862 44801846 45041784 45041672 44941587 44541421 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Sat Aug 26 2023 Valid 262000Z - 271200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING ACROSS THE SOUTHEAST MO/NORTHEAST AR VICINITY... ...SUMMARY... Occasional damaging gusts will be possible this afternoon and evening across southeast Missouri/northeast Arkansas and vicinity, with more isolated strong winds possible into the southern Appalachians and across parts of Idaho and Oregon. ...20Z Update... Overall, no changes are needed to the previous outlook. More forecast details provided below and in the appended outlook. ...Southeast MO/northeast AR area this afternoon/evening... As mentioned in recently issued MCD #2054, thunderstorms capable of producing isolated to scattered damaging winds will become increasingly possible later this afternoon across parts of southern MO/IL, northern AR, and western KY/TN. Strong heating and large PW will support a threat of at least isolated wet microbursts as these storms sag southward through the afternoon. ...Southern Appalachians into the Central Carolinas... As discussed in MCD #2055, strong heating ahead of an eastward-progressing MCV, along with typical diurnal terrain circulations should support additional thunderstorm development through this afternoon. Moderate buoyancy (1000-2000 J/kg of MLCAPE) and fairly steep low-level lapse rates should support occasional strong updrafts. As result, isolated strong to severe storms, with the potential for a few damaging downburst gusts, will be possible this afternoon and evening across the region. ...Southern ID/Eastern OR... Thunderstorm development has already be observed across the region ahead of the approaching speed max, with additional storm development still possible this afternoon/evening. Modest vertical shear could help organize updrafts, with high cloud bases and steep low-level lapse rates contributing to the potential for isolated strong/severe outflow. ..Mosier.. 08/26/2023 .PREV DISCUSSION... /ISSUED 1127 AM CDT Sat Aug 26 2023/ ...Southeast MO/northeast AR area this afternoon/evening... The persistent midlevel high continues to slowly weaken over the southern Plains, while a series of MCVs rotate around the northern and eastern periphery of the high, from KS to the southern Appalachians. The most pronounced MCV is now moving southeastward over northwest MO and will interact with the unstable warm sector this afternoon in the vicinity of southeast MO, where additional thunderstorm development is expected south of the ongoing convection near Saint Louis. Daytime heating in cloud breaks and boundary-layer dewpoints in the mid 70s will result in MLCAPE of 2500-3000 J/kg, and lapse rate profiles will also favor strong downdrafts (DCAPE of 1000-1500 J/kg). Primarily multicell clusters are expected as a result of weak vertical shear in the warm sector ahead of the MCV. Damaging outflow winds will be the main severe threat from mid-late afternoon into this evening. ...Southern ID/eastern OR this afternoon/evening... A weak mid-upper speed max is translating northward around the western periphery of the ridge from the southern Plains into the Rockies. A band of ascent and midlevel moisture, coincident with surface heating in cloud breaks, will support scattered thunderstorm development this afternoon into this evening. Typical inverted-V profiles and some modest enhancement to deep-layer vertical shear will support somewhat organized cells (and perhaps a low-end supercell) capable of producing isolated strong-severe outflow gusts. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0226 PM CDT Sat Aug 26 2023 Valid 271200Z - 281200Z Added an Elevated delineation for portions of central and northern Texas and southwest Oklahoma. Given the extreme to exceptional drought ongoing, northerly winds behind the cold front (15 gust 25 mph) may be sufficiently strong to support an increased fire weather threat despite only marginally dry relative humidity (30-35 percent). Elsewhere, the forecast remains on track with relatively benign fire weather conditions. ..Bentley.. 08/26/2023 .PREV DISCUSSION... /ISSUED 0148 AM CDT Sat Aug 26 2023/ ...Synopsis... On Sunday, the central/western US upper-level ridge will shift westward across the Four Corners. A cold front will sag southward across the Southern Plains bringing a shift to northerly flow, cooling temperatures, and rain and thunderstorm chances. While this looks like a better chance for more widespread wetting rainfall across Central Texas and southern Louisiana, more appreciable totals will likely remain somewhat localized. Due to the extremely critical nature of fuels, areas that receive very little rainfall will likely not see much change in fuel status and potential for new lightning starts. Humidity will increase with cooler temperatures behind the front. Relative humidity will be around 20 percent across central Texas ahead of the passing front, which may allow for some locally Elevated conditions. Overall, the threat is too centralized for inclusion of any Elevated highlights. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Fri Aug 25 22:26:02 UTC 2023.

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0442 PM CDT Fri Aug 25 2023 Valid 271200Z - 021200Z ...D5/Tue-D6/Wed - Texas into Louisiana... A cold front will move through the southern Plains on Sunday. In the wake of this cold front, a dry, continental airmass will move into place across much of the Plains and into parts of the Southeast. The lowest RH is expected across the regions of severe to exceptional drought across portions of Texas and Louisiana. Initially, winds behind the front will be weak on Sunday and Monday. However, on Tuesday and Wednesday, northerly/northeasterly winds will strengthen as the pressure gradient tightens between High Pressure in the central High Plains and a developing tropical system in the Gulf of Mexico. Elevated to potentially critical conditions are likely on Tuesday and Wednesday amid these strengthening post-frontal winds. ...D5/Tue - Northwest... On Tuesday, a strong mid-level trough will move across the Northwest. This system will bring the potential for thunderstorms. Any thunderstorms in western Oregon and Washington could have some concern for new lightning starts. However, less favorable fuels east of the Cascades, combined with 1+ inch PWAT values should mitigate the threat somewhat. In addition, strong winds are expected to develop as the pressure gradient tightens across the Cascades. The strongest winds will likely be in the higher terrain of the Cascades, in the Cascade gaps and in the Columbia Basin. At this time it does not appear relative humidity will be low enough, particularly where fuels are dry, to support Critical probabilities. ...D6/Wed - Northern Rockies... On Wednesday, the strong mid-level jet will move east and affect a large portion of Montana. Dry and breezy conditions are expected with some critical conditions likely. However, fuels in this area are not that favorable for large fire spread. Some drying of fuels may occur by then, and a greater threat may materialize, but for now there is enough uncertainty about fuels to preclude any Critical probabilities. ..Bentley.. 08/25/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 2048 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR WESTERN KS INTO EXTREME SOUTHERN NE
Mesoscale Discussion 2048 NWS Storm Prediction Center Norman OK 0354 PM CDT Fri Aug 25 2023 Areas affected...Western KS into extreme southern NE Concerning...Severe potential...Watch unlikely Valid 252054Z - 252300Z Probability of Watch Issuance...20 percent SUMMARY...Storms capable of hail and isolated severe gusts may increase through late afternoon. DISCUSSION...Storms are gradually increasing in coverage this afternoon from southwest NE into northwest KS, near/north of a surface low near the CO/KS state line. Thus far, the strongest storms have been to the cool side of a surface boundary across extreme southwest NE, where otherwise-weak deep-layer shear is slightly stronger due to surface northeasterly winds. Occasional strong multicells in this region may pose an isolated hail and severe gusts threat through the afternoon. Additional deepening cumulus is noted within the hot/well-mixed environment south of the surface boundary into a larger portion of western KS. As storms deepen/mature within this regime, inverted-V profiles will support a threat of isolated severe downbursts through late afternoon. Outflow consolidation may eventually result in a loosely organized cluster, but the short-term threat is expected to remain disorganized and rather isolated, rendering watch issuance unlikely. ..Dean/Thompson.. 08/25/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TOP...ICT...GID...LBF...DDC...GLD... LAT...LON 37900120 39040184 39940165 40510114 40219778 39559755 39019775 38399831 38039963 37980047 37900120 Read more

MD 2047 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF SOUTHERN IL/IN
Mesoscale Discussion 2047 NWS Storm Prediction Center Norman OK 0325 PM CDT Fri Aug 25 2023 Areas affected...Parts of southern IL/IN Concerning...Severe potential...Watch unlikely Valid 252025Z - 252230Z Probability of Watch Issuance...20 percent SUMMARY...Isolated severe storms are possible later this afternoon into the evening, with a threat of locally damaging wind and perhaps some hail. DISCUSSION...A strong thunderstorm has recently developed across south-central IL, with an increasing cumulus field noted farther east along a surface boundary into southeast IL and southern IN. Strong to extreme buoyancy has developed within a very hot/moist environment, with MLCAPE in the 3000-4500 J/kg range per recent mesoanalyses and also noted regionally on the 18 UTC ILN sounding. While deep-layer shear is rather weak (with effective shear generally less than 25 kt), the favorable buoyancy will support a threat of isolated hail and localized downbursts with any sustained development through the afternoon. Storm coverage through the afternoon remains somewhat uncertain, with generally limited large-scale ascent and weak convergence along the boundary. With the threat expected to remain somewhat isolated, watch issuance in the short-term is considered unlikely. ..Dean/Thompson.. 08/25/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ILN...LMK...IND...PAH...ILX...LSX... LAT...LON 39808935 39378766 39558605 39338490 38848482 38178595 38078740 38458936 38918970 39128986 39808935 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Fri Aug 25 2023 Valid 252000Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL ILLINOIS INTO PARTS OF INDIANA... ...SUMMARY... Isolated to scattered thunderstorms associated with strong wind gusts and marginally severe hail are possible this afternoon and evening from Kansas to Virginia and across Upper Michigan, with the somewhat greater threat focused from central Illinois into southwest Indiana. Only minor changes were made at 20Z, including adjusting low probabilities farther across eastern Upper MI ahead of a frontal wave, and expanding a low wind threat into more of southeast KS and southern MO where a few storms have formed within the hot air mass. A small 2% tornado area has also been added for the area from far southern OH into a small part of northeast KY. Here, objective analysis indicates 0-1 SRH near 100 m2/s2, which may aid rotation potential in the area north of the primary KY MCS. ..Jewell.. 08/25/2023 .PREV DISCUSSION... /ISSUED 1127 AM CDT Fri Aug 25 2023/ ...IL/IN this afternoon/evening... An outflow-reinforced front extends from WV/southern OH to central IL, while a second outflow surge is moving southeastward into northern MO and west central IL. The merger zone of these two boundaries appears to be the more probable area for thunderstorm development this afternoon into IL, along the north gradient of the 78-80 F boundary-layer dewpoints. Modified 12z soundings and short-term model forecasts suggest that MLCAPE could exceed 4000 J/kg with weakening convective inhibition, while steep midlevel lapse rates will also result in large DCAPE (> 1200 J/kg). With most of the vertical shear (25-30 kt magnitudes) concentrated in the lowest 3 km, the primary convective mode is expected to be multicell clusters and perhaps a relatively short-lived supercell or two capable of producing damaging outflow winds. ...Eastern KY to VA through this evening... The remnants of overnight convection persist from WV into eastern KY. The warmest surface temperatures and higher dewpoints to the west across KY suggest that the preferred development of new storms will also be toward the west and southwest this afternoon, where isolated strong downburst winds will be possible. Farther east into VA, somewhat lesser boundary-layer moisture (mixed mainly into the mid-upper 60s) and lesser midlevel lapse rates will support weaker buoyancy (MLCAPE in the 1500-2000 J/kg range) compared to KY/southern OH. Despite the early passage of the convectively-enhanced midlevel trough, 25-30 kt midlevel flow will linger over VA/MD this afternoon. Thunderstorm development will be possible this afternoon along a weak lee trough, as well as any persistent differential heating zones (mainly across southwest VA) and along a cold front moving southeastward from PA. The overall threat for damaging winds with downbursts still appears to be best categorized as MRGL, so will maintain the 5% wind probabilities. ...Northeast MN into Upper MI this afternoon/evening... A pronounced midlevel shortwave trough is moving east-southeastward over the MN Arrowhead/Lake Superior. A narrow zone of destabilization coincident with a band of ascent will support at least widely thunderstorms through the afternoon. Though buoyancy will be modest (MLCAPE of 500-1000 J/kg), long hodographs will support organized/supercell storms capable of producing isolated wind damage and marginally severe hail. ...Eastern CO to KS/NE border this afternoon/evening... As the surface warms with daytime heating, high-based thunderstorm development is expected along a slow-moving front in KS and in a zone of low-level upslope flow in CO by mid-late afternoon. Vertical shear will be relatively weak, but deep inverted-V profiles with large DCAPE will support the potential for strong to isolated severe outflow gusts this afternoon into this evening. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0205 PM CDT Fri Aug 25 2023 Valid 261200Z - 271200Z ...NO CRITICAL AREAS... No changes. See previous discussion below. ..Bentley.. 08/25/2023 .PREV DISCUSSION... /ISSUED 0116 AM CDT Fri Aug 25 2023/ ...Synopsis... Strong upper-level ridging across the central/western US will generally keep winds light across much of the CONUS where fuels are the driest on Saturday. A weak disturbance moving across northern Montana may lead to locally breezy and dry conditions but relative humidity looks to stay largely above 20 percent. Hot and dry conditions will continue across portions of Texas and Louisiana where well below normal rainfall has led to extreme to exceptional drought and extremely critically dry fuels. Winds within this region will remain light and preclude the need to include any areas at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0655 Status Updates
STATUS FOR WATCH 0655 HAS NOT BEEN ISSUED YET Read more

WW 655 SEVERE TSTM IL WI LM 242205Z - 250300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 655 NWS Storm Prediction Center Norman OK 505 PM CDT Thu Aug 24 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northeast Illinois Southern Wisconsin Lake Michigan * Effective this Thursday afternoon and evening from 505 PM until 1000 PM CDT. * Primary threats include... Scattered damaging winds and isolated significant gusts to 80 mph possible Isolated very large hail events to 2 inches in diameter possible A tornado or two possible SUMMARY...Thunderstorms are rapidly developing across southern Wisconsin. These storms will track southeastward across the watch area this afternoon and early evening, posing a risk of locally damaging wind gusts and hail. The severe thunderstorm watch area is approximately along and 80 statute miles east and west of a line from 35 miles west northwest of Milwaukee WI to 30 miles southeast of Janesville WI. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU5). 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 654... AVIATION...A few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 70 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 24035. ...Hart Read more

WW 0654 Status Updates
STATUS REPORT ON WW 654 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..SPC..08/24/23 ATTN...WFO...FGF...BIS... STATUS REPORT FOR WS 654 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NDC005-009-019-025-027-031-049-055-057-061-065-069-071-079-083- 095-101-103-242340- ND . NORTH DAKOTA COUNTIES INCLUDED ARE BENSON BOTTINEAU CAVALIER DUNN EDDY FOSTER MCHENRY MCLEAN MERCER MOUNTRAIL OLIVER PIERCE RAMSEY ROLETTE SHERIDAN TOWNER WARD WELLS 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 654 SEVERE TSTM ND 241945Z - 250100Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 654 NWS Storm Prediction Center Norman OK 245 PM CDT Thu Aug 24 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of West-central to northeast North Dakota * Effective this Thursday afternoon and evening from 245 PM until 800 PM CDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2 inches in diameter possible Isolated damaging wind gusts to 70 mph possible A tornado or two possible SUMMARY...A few supercells should persist along and ahead of a surface cold front with threats of large hail, along with isolated severe gusts, and a brief tornado. The severe thunderstorm watch area is approximately along and 45 statute miles north and south of a line from 55 miles west of Garrison ND to 25 miles northeast of Devils Lake ND. 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. && 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 450. Mean storm motion vector 26025. ...Grams Read more

MD 2039 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR SOUTHERN LOWER MI...NORTHEAST IN...NORTHWEST OH
Mesoscale Discussion 2039 NWS Storm Prediction Center Norman OK 0344 PM CDT Thu Aug 24 2023 Areas affected...Southern Lower MI...Northeast IN...Northwest OH Concerning...Severe potential...Watch likely Valid 242044Z - 242315Z Probability of Watch Issuance...95 percent SUMMARY...Potential for severe thunderstorms will increase throughout the afternoon and into the evening across Lower MI and adjacent portions of northeast IN and northwest OH. All severe hazards are possible, including significant wind gusts and tornadoes. DISCUSSION...Visible satellite imagery has shown significant erosion of the stratus across southwest Lower MI as the differential heating zone becomes an effective warm front amid strong southwesterly surface winds. Dewpoints are now in the upper 70s with temperatures in the upper 80s/low 90s across southwest Lower MI. Temperatures are still in the upper 70s/low 80s farther north and east, with lower dewpoints there as well. Even with the more moist and warmer conditions, some convective inhibition currently still remains across southwest Lower MI, evidenced by the billow clouds on visible imagery. Additional heating, coupled with low-level moisture convergence over the region, may be able to overcome this convective inhibition, promoting warm-sector thunderstorm development. There is some uncertainty regarding this scenario, but any warm-sector storms that do form would likely be supercellular and capable of all severe hazards, including tornadoes. Even if warm-sector development is not realized, additional forcing for ascent attendant to subtle vorticity maximum should spread across the area this evening. This forcing for ascent is just now reaching southern WI and is responsible for the developing storms in that region now. Expectation is that any storms ongoing ahead of this vorticity max will intensify as they enter southern Lower MI, with some in-situ development possible as well. Upscale growth appears probable, with the resultant convective line then progressing eastward/southeastward. Damaging gusts would be the main severe threat, but hail and a tornado or two are possible as well. It is feasible that a robust rear-inflow jet develops, resulting in the potential for significant wind gusts and QLCS tornadoes. ..Mosier/Grams.. 08/24/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CLE...DTX...IWX...GRR... LAT...LON 42078654 42608634 43468614 43528482 42568330 41838318 41338381 41448535 41808627 42078654 Read more

MD 2038 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR THE WESTERN DAKOTAS INTO NORTHWEST NEBRASKA
Mesoscale Discussion 2038 NWS Storm Prediction Center Norman OK 0341 PM CDT Thu Aug 24 2023 Areas affected...The western Dakotas into northwest Nebraska Concerning...Severe potential...Watch unlikely Valid 242041Z - 242245Z Probability of Watch Issuance...20 percent SUMMARY...Isolated thunderstorms are expected to develop through the late afternoon and into the early evening. Thunderstorm coverage will likely remain too limited to warrant watch issuance, but strong to severe winds and large hail are possible. DISCUSSION...Latest GOES visible imagery shows gradually deepening cumulus along a surface trough from southwest ND into western NE/southeast WY. Parts of this region - mainly the SD/NE border area - have been slow to destabilize due to residual cloud cover, but MLCIN has been steadily diminishing amid boundary-layer warming as temperatures climb into the upper 80s and low 90s. Recent forecast soundings suggest temperatures in the low 90s are required to completely remove mixed-layer inhibition, which is slowly ongoing per recent surface observations. Consequently, thermodynamic profiles should steadily become more favorable for initiation and maintenance of convection over the next couple of hours. Forcing for ascent over the region is expected to remain fairly modest as the main synoptic trough passes to the north along the international border. This will likely limit storm coverage and maintain an fairly isolated severe threat, and storm motions off the surface trough will favor more initially discrete storm modes. 30-40 knot mid-level flow on the southern periphery of the upper wave will support effective bulk shear values near 35 knots, favorable for supercells with an attendant severe wind/hail risk. More deeply mixed low-level profiles across southwest SD into NE will likely support accelerating downdrafts via evaporative cooling processes. In turn, this may support a locally-higher potential for strong to severe gusts. Regardless, given the expected limited coverage of storms, watch issuance is not anticipated. ..Moore/Grams.. 08/24/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ABR...BIS...LBF...UNR...CYS... LAT...LON 43560378 45000355 46110332 46640274 46620139 45900099 44550128 43150162 41790267 41770316 42020365 42220427 42620450 43560378 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0255 PM CDT Thu Aug 24 2023 Valid 242000Z - 251200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN LOWER MICHIGAN INTO WESTERN PENNSYLVANIA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER NORTH DAKOTA...AND FROM LAKE MICHIGAN TO CENTRAL PENNSYLVANIA AND WESTERN NEW YORK... ...SUMMARY... A swath of severe thunderstorms appears increasingly likely to occur across parts of southern Lower Michigan through northern Ohio and northwest Pennsylvania this evening. Damaging winds with localized significant severe wind gusts in excess of 75 mph along with a few tornadoes should be the primary hazards. ...Great Lakes Region... Little change was needed for the 20Z update. A very unstable air mass will continue to develop northeastward across Lower MI, Lake Erie and southwest Ontario through this evening, as heights begin to fall ahead of a developing shortwave trough to the northwest. A leading disturbance will likely aid storm formation close to Lake MI later this afternoon. This activity is likely to grow upscale during the evening and into the night as it moves southeastward out of Lower MI. Damaging winds will be likely given the extreme instability and expected MCS mode. Swaths of significant gusts are possible given the steep midlevel lapse rates and substantial precipitable water aiding updraft/downdraft potential. A few of the stronger storms may additionally produce large hail, especially the early development from southeast WI into western Lower MI later this afternoon. For more information see MCD 2037. ...Northern Plains... Scattered severe cells producing hail appear likely this afternoon from ND into northwest MN as a cold front interacts with a destabilizing air mass and an upper trough grazes the region. Hail potential will be aided by substantial hodograph length with effective shear around 50 kt, along with steep lapse rates. See MCD 2036 for more information. ..Jewell.. 08/24/2023 .PREV DISCUSSION... /ISSUED 1130 AM CDT Thu Aug 24 2023/ ...Central to Lower Great Lakes and Upper OH Valley... In the wake of decaying elevated convection earlier this morning, substantially decreasing cloudiness is well underway across most of OH into southern Lower MI. A very moist boundary layer persists to the west of an arcing convective outflow bisecting IN that will largely mix out and advect east this afternoon. This increasing moisture coupled with rather steep mid-level lapse rates sampled in the 12Z DTX/GRB soundings, in conjunction with the surface heating recovery will yield a plume of very large MLCAPE spreading into southern Lower MI. This will result in a substantial MLCAPE gradient from south to north across the lower peninsula, with a more west to east gradient farther east downstream of the Lower Great Lakes. A low-amplitude mid-level disturbance and related speed max over eastern ON into Upper MI should progress into southeast ON, with trailing belt of weakly forced ascent aiding in a minor frontal wave over south-central WI tracking towards southwest Lower MI by early evening. The west-east corridor ahead of this wave across southern Lake MI, southern/central Lower Michigan toward the Lake Erie vicinity is where deep convection is most likely to initiate towards 00Z. Intense storm development can be expected including some initial supercells capable of large hail and possibly a tornado threat, which could somewhat focus across southeast Lower MI near the warm front/surface wave. Storms should quickly increase and organize through the evening toward the Lake Erie vicinity including northern OH/western PA, with damaging wind potential becoming more prevalent. Given the very large instability, some threat for localized gusts in excess of 75 mph will exist as an MCS matures, with the possibility of a QLCS-related tornado risk also persisting. The severe wind threat should continue through the evening into and across parts of the upper Ohio Valley and central Appalachians before convection eventually weakens. Confidence is adequate to warrant an upgrade of damaging wind probabilities for a level 3 of 5 severe risk. ...ND and northwest MN... A shortwave trough over southwest SK should track east-southeast into southeast MB through tonight. Ascent associated with this trough along with modest low-level convergence along a weak front, should encourage convection to develop late this afternoon across parts of ND. Weak to moderate buoyancy and strong deep-layer shear will support organized updrafts with a few supercells and multicell clusters expected. Scattered large hail and isolated severe wind gusts should be the main threat with these thunderstorms as they move eastward into parts of northwest MN through this evening. Confidence is adequate to warrant an upgrade of the large hail probabilities for a level 2 of 5 severe risk. ...Western SD/NE... At least isolated high-based convection should form towards late afternoon near the Black Hills and along a lee trough. While deep-layer shear should be weaker with southward extent across this area relative to ND, it may still be sufficient for loosely organized multicells posing an isolated severe wind and marginal severe hail threat through the early evening. ...Central/Southern Appalachians... A pair of remnant MCVs and related convective outflows from early-day convection should spread south within a modest mid-level northerly flow regime. Ahead of these features, continued boundary-layer heating within the west/east-oriented MLCAPE gradient should support some threat for loosely organized multicells capable of producing sporadic strong to damaging wind gusts. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0255 PM CDT Thu Aug 24 2023 Valid 242000Z - 251200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN LOWER MICHIGAN INTO WESTERN PENNSYLVANIA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER NORTH DAKOTA...AND FROM LAKE MICHIGAN TO CENTRAL PENNSYLVANIA AND WESTERN NEW YORK... ...SUMMARY... A swath of severe thunderstorms appears increasingly likely to occur across parts of southern Lower Michigan through northern Ohio and northwest Pennsylvania this evening. Damaging winds with localized significant severe wind gusts in excess of 75 mph along with a few tornadoes should be the primary hazards. ...Great Lakes Region... Little change was needed for the 20Z update. A very unstable air mass will continue to develop northeastward across Lower MI, Lake Erie and southwest Ontario through this evening, as heights begin to fall ahead of a developing shortwave trough to the northwest. A leading disturbance will likely aid storm formation close to Lake MI later this afternoon. This activity is likely to grow upscale during the evening and into the night as it moves southeastward out of Lower MI. Damaging winds will be likely given the extreme instability and expected MCS mode. Swaths of significant gusts are possible given the steep midlevel lapse rates and substantial precipitable water aiding updraft/downdraft potential. A few of the stronger storms may additionally produce large hail, especially the early development from southeast WI into western Lower MI later this afternoon. For more information see MCD 2037. ...Northern Plains... Scattered severe cells producing hail appear likely this afternoon from ND into northwest MN as a cold front interacts with a destabilizing air mass and an upper trough grazes the region. Hail potential will be aided by substantial hodograph length with effective shear around 50 kt, along with steep lapse rates. See MCD 2036 for more information. ..Jewell.. 08/24/2023 .PREV DISCUSSION... /ISSUED 1130 AM CDT Thu Aug 24 2023/ ...Central to Lower Great Lakes and Upper OH Valley... In the wake of decaying elevated convection earlier this morning, substantially decreasing cloudiness is well underway across most of OH into southern Lower MI. A very moist boundary layer persists to the west of an arcing convective outflow bisecting IN that will largely mix out and advect east this afternoon. This increasing moisture coupled with rather steep mid-level lapse rates sampled in the 12Z DTX/GRB soundings, in conjunction with the surface heating recovery will yield a plume of very large MLCAPE spreading into southern Lower MI. This will result in a substantial MLCAPE gradient from south to north across the lower peninsula, with a more west to east gradient farther east downstream of the Lower Great Lakes. A low-amplitude mid-level disturbance and related speed max over eastern ON into Upper MI should progress into southeast ON, with trailing belt of weakly forced ascent aiding in a minor frontal wave over south-central WI tracking towards southwest Lower MI by early evening. The west-east corridor ahead of this wave across southern Lake MI, southern/central Lower Michigan toward the Lake Erie vicinity is where deep convection is most likely to initiate towards 00Z. Intense storm development can be expected including some initial supercells capable of large hail and possibly a tornado threat, which could somewhat focus across southeast Lower MI near the warm front/surface wave. Storms should quickly increase and organize through the evening toward the Lake Erie vicinity including northern OH/western PA, with damaging wind potential becoming more prevalent. Given the very large instability, some threat for localized gusts in excess of 75 mph will exist as an MCS matures, with the possibility of a QLCS-related tornado risk also persisting. The severe wind threat should continue through the evening into and across parts of the upper Ohio Valley and central Appalachians before convection eventually weakens. Confidence is adequate to warrant an upgrade of damaging wind probabilities for a level 3 of 5 severe risk. ...ND and northwest MN... A shortwave trough over southwest SK should track east-southeast into southeast MB through tonight. Ascent associated with this trough along with modest low-level convergence along a weak front, should encourage convection to develop late this afternoon across parts of ND. Weak to moderate buoyancy and strong deep-layer shear will support organized updrafts with a few supercells and multicell clusters expected. Scattered large hail and isolated severe wind gusts should be the main threat with these thunderstorms as they move eastward into parts of northwest MN through this evening. Confidence is adequate to warrant an upgrade of the large hail probabilities for a level 2 of 5 severe risk. ...Western SD/NE... At least isolated high-based convection should form towards late afternoon near the Black Hills and along a lee trough. While deep-layer shear should be weaker with southward extent across this area relative to ND, it may still be sufficient for loosely organized multicells posing an isolated severe wind and marginal severe hail threat through the early evening. ...Central/Southern Appalachians... A pair of remnant MCVs and related convective outflows from early-day convection should spread south within a modest mid-level northerly flow regime. Ahead of these features, continued boundary-layer heating within the west/east-oriented MLCAPE gradient should support some threat for loosely organized multicells capable of producing sporadic strong to damaging wind gusts. Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0227 PM CDT Thu Aug 24 2023 Valid 261200Z - 011200Z Upper ridging will prevail across the south-central CONUS through the remainder of this week into the middle of next week, with multiple mid-level perturbations expected to crest the ridge through the forecast period. Through the upcoming weekend, hot and dry surface conditions will persist across the Southern Plains into the Lower Mississippi Valley, with little appreciable rainfall expected. Medium-range guidance is in fair agreement that a pronounced mid-level impulse will pivot around the upper ridge, encouraging the southward surging of a cold front across the southern Plains around Day 6/Tuesday. Dry northwesterly surface winds will accompany the cold front, especially across northern TX on Tuesday, where 40 percent Critical Probabilities have been added. Meanwhile. multiple mid-level troughs will encourage occasional bouts of thunderstorms and windy/potentially dry surface conditions across portions of the Pacific Northwest into the northern Plains through the period. However, lack of widespread receptive fuels east of the Cascades, and uncertainty in coverage of thunderstorms or dry/breezy conditions west of the Cascades, precludes Critical probabilities this outlook. ..Squitieri.. 08/24/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0227 PM CDT Thu Aug 24 2023 Valid 261200Z - 011200Z Upper ridging will prevail across the south-central CONUS through the remainder of this week into the middle of next week, with multiple mid-level perturbations expected to crest the ridge through the forecast period. Through the upcoming weekend, hot and dry surface conditions will persist across the Southern Plains into the Lower Mississippi Valley, with little appreciable rainfall expected. Medium-range guidance is in fair agreement that a pronounced mid-level impulse will pivot around the upper ridge, encouraging the southward surging of a cold front across the southern Plains around Day 6/Tuesday. Dry northwesterly surface winds will accompany the cold front, especially across northern TX on Tuesday, where 40 percent Critical Probabilities have been added. Meanwhile. multiple mid-level troughs will encourage occasional bouts of thunderstorms and windy/potentially dry surface conditions across portions of the Pacific Northwest into the northern Plains through the period. However, lack of widespread receptive fuels east of the Cascades, and uncertainty in coverage of thunderstorms or dry/breezy conditions west of the Cascades, precludes Critical probabilities this outlook. ..Squitieri.. 08/24/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more