Severe Storms

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Mon Sep 04 2023 Valid 042000Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN PLAINS/NORTHERN AND CENTRAL HIGH PLAINS... ...SUMMARY... Isolated severe wind gusts and large hail remain possible over parts of the northern Plains this afternoon and evening, particularly from parts of eastern Wyoming to the Dakotas. ...Discussion... Little change appears necessary to the ongoing outlook at this time, as the convective scenario across the U.S. continues to largely evolve as expected. The primary change has been to extend severe risk southward across more of the central High Plains region. Here, scant low-level moisture and limited CAPE, but a dry sub-cloud layer may support gusty/isolated damaging wind gusts where storms are currently developing. ..Goss.. 09/04/2023 .PREV DISCUSSION... /ISSUED 1141 AM CDT Mon Sep 04 2023/ ...Northern Plains... An upper trough over the Intermountain West/north-central Rockies will continue northeastward toward the Dakotas, with thunderstorms expected to increase near/behind an advancing cold front this afternoon, initially across interior/eastern portions of Wyoming and far southeast Montana. Strengthening winds aloft, steep lapse rates, and modest overall buoyancy will support high-based storms capable of large hail and strong wind gusts. Storms will likely further increase, aggregate, and grow upscale into northeast Wyoming/western South Dakota and eventually North Dakota this evening, with the potential for severe-caliber wind gusts expected to steadily increase accordingly. This also includes some potential for significant wind gusts (65+ kt). ...Ozarks/Mid-South... Widely scattered to scattered, multicellular thunderstorms are expected to increase across the region this afternoon with the potential for localized wind damage, and possibly some sporadic hail near severe limits. This will be as the upper low transitions northeastward toward the region and interfaces with a moderately to strongly unstable boundary layer, with moderately strong winds aloft (25-30 kt at 500 mb? likely contributing to some semi-sustained multicells. Any such severe risk should diminish by around sunset. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Mon Sep 04 2023 Valid 042000Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN PLAINS/NORTHERN AND CENTRAL HIGH PLAINS... ...SUMMARY... Isolated severe wind gusts and large hail remain possible over parts of the northern Plains this afternoon and evening, particularly from parts of eastern Wyoming to the Dakotas. ...Discussion... Little change appears necessary to the ongoing outlook at this time, as the convective scenario across the U.S. continues to largely evolve as expected. The primary change has been to extend severe risk southward across more of the central High Plains region. Here, scant low-level moisture and limited CAPE, but a dry sub-cloud layer may support gusty/isolated damaging wind gusts where storms are currently developing. ..Goss.. 09/04/2023 .PREV DISCUSSION... /ISSUED 1141 AM CDT Mon Sep 04 2023/ ...Northern Plains... An upper trough over the Intermountain West/north-central Rockies will continue northeastward toward the Dakotas, with thunderstorms expected to increase near/behind an advancing cold front this afternoon, initially across interior/eastern portions of Wyoming and far southeast Montana. Strengthening winds aloft, steep lapse rates, and modest overall buoyancy will support high-based storms capable of large hail and strong wind gusts. Storms will likely further increase, aggregate, and grow upscale into northeast Wyoming/western South Dakota and eventually North Dakota this evening, with the potential for severe-caliber wind gusts expected to steadily increase accordingly. This also includes some potential for significant wind gusts (65+ kt). ...Ozarks/Mid-South... Widely scattered to scattered, multicellular thunderstorms are expected to increase across the region this afternoon with the potential for localized wind damage, and possibly some sporadic hail near severe limits. This will be as the upper low transitions northeastward toward the region and interfaces with a moderately to strongly unstable boundary layer, with moderately strong winds aloft (25-30 kt at 500 mb? likely contributing to some semi-sustained multicells. Any such severe risk should diminish by around sunset. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Mon Sep 04 2023 Valid 042000Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN PLAINS/NORTHERN AND CENTRAL HIGH PLAINS... ...SUMMARY... Isolated severe wind gusts and large hail remain possible over parts of the northern Plains this afternoon and evening, particularly from parts of eastern Wyoming to the Dakotas. ...Discussion... Little change appears necessary to the ongoing outlook at this time, as the convective scenario across the U.S. continues to largely evolve as expected. The primary change has been to extend severe risk southward across more of the central High Plains region. Here, scant low-level moisture and limited CAPE, but a dry sub-cloud layer may support gusty/isolated damaging wind gusts where storms are currently developing. ..Goss.. 09/04/2023 .PREV DISCUSSION... /ISSUED 1141 AM CDT Mon Sep 04 2023/ ...Northern Plains... An upper trough over the Intermountain West/north-central Rockies will continue northeastward toward the Dakotas, with thunderstorms expected to increase near/behind an advancing cold front this afternoon, initially across interior/eastern portions of Wyoming and far southeast Montana. Strengthening winds aloft, steep lapse rates, and modest overall buoyancy will support high-based storms capable of large hail and strong wind gusts. Storms will likely further increase, aggregate, and grow upscale into northeast Wyoming/western South Dakota and eventually North Dakota this evening, with the potential for severe-caliber wind gusts expected to steadily increase accordingly. This also includes some potential for significant wind gusts (65+ kt). ...Ozarks/Mid-South... Widely scattered to scattered, multicellular thunderstorms are expected to increase across the region this afternoon with the potential for localized wind damage, and possibly some sporadic hail near severe limits. This will be as the upper low transitions northeastward toward the region and interfaces with a moderately to strongly unstable boundary layer, with moderately strong winds aloft (25-30 kt at 500 mb? likely contributing to some semi-sustained multicells. Any such severe risk should diminish by around sunset. Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0216 PM CDT Mon Sep 04 2023 Valid 061200Z - 121200Z The potential for critical fire weather conditions appears low through the extended period. Long-range guidance continues to show a building upper ridge over northern Mexico and into the Southwest region through the mid/late week period, which will maintain warm and dry conditions from west TX to the Four Corners. There is a signal in ensemble guidance for 15-25 mph winds across the greater Four Corners region D3/Wednesday into D4/Thursday as a shortwave trough passes through the Pacific Northwest and augments the regional pressure gradient. However, recent reports and ERC analyses indicate fuels are not currently receptive and may require multiple days of drying before supporting a fire weather concern. Across the Plains where fuels are currently dry, ensemble clusters show a reasonably good signal for increasing rain chances across the Plains starting D5/Friday into early next week. While some areas may remain dry, the potential for wetting rain over the broader region limits confidence in the overall fire weather threat at this range. ..Moore.. 09/04/2023 ...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 0216 PM CDT Mon Sep 04 2023 Valid 061200Z - 121200Z The potential for critical fire weather conditions appears low through the extended period. Long-range guidance continues to show a building upper ridge over northern Mexico and into the Southwest region through the mid/late week period, which will maintain warm and dry conditions from west TX to the Four Corners. There is a signal in ensemble guidance for 15-25 mph winds across the greater Four Corners region D3/Wednesday into D4/Thursday as a shortwave trough passes through the Pacific Northwest and augments the regional pressure gradient. However, recent reports and ERC analyses indicate fuels are not currently receptive and may require multiple days of drying before supporting a fire weather concern. Across the Plains where fuels are currently dry, ensemble clusters show a reasonably good signal for increasing rain chances across the Plains starting D5/Friday into early next week. While some areas may remain dry, the potential for wetting rain over the broader region limits confidence in the overall fire weather threat at this range. ..Moore.. 09/04/2023 ...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 0216 PM CDT Mon Sep 04 2023 Valid 061200Z - 121200Z The potential for critical fire weather conditions appears low through the extended period. Long-range guidance continues to show a building upper ridge over northern Mexico and into the Southwest region through the mid/late week period, which will maintain warm and dry conditions from west TX to the Four Corners. There is a signal in ensemble guidance for 15-25 mph winds across the greater Four Corners region D3/Wednesday into D4/Thursday as a shortwave trough passes through the Pacific Northwest and augments the regional pressure gradient. However, recent reports and ERC analyses indicate fuels are not currently receptive and may require multiple days of drying before supporting a fire weather concern. Across the Plains where fuels are currently dry, ensemble clusters show a reasonably good signal for increasing rain chances across the Plains starting D5/Friday into early next week. While some areas may remain dry, the potential for wetting rain over the broader region limits confidence in the overall fire weather threat at this range. ..Moore.. 09/04/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1250 PM CDT Mon Sep 04 2023 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... The previous forecast remains on track. Latest guidance continues to show poor spatial and temporal overlap of strong winds and sub-25% RH across the southern/central Plains ahead of and behind a southeastward moving cold front. Isolated thunderstorms along the front are also possible by late afternoon across northwest TX into OK, which may further limit the fire weather threat. While a few dry thunderstorms are possible on the southwestern fringe of the front across west TX, confidence in storm coverage is too limited for highlights. ..Moore.. 09/04/2023 .PREV DISCUSSION... /ISSUED 1256 AM CDT Mon Sep 04 2023/ ...Synopsis... The upper-level trough in the central/northern Plains will continue to the northeast on Tuesday. This trough and an attendant surface cyclone will move into the upper Midwest by the afternoon. A cold front will progress into the central Plains and parts of the southern Plains. ...Northwest Texas into Kansas... Breezy conditions appear probable ahead of and behind the cold front. The strongest winds are expected Tuesday morning, particularly over eastern Kansas where the low-level jet will be strongest. By the afternoon, the surface pressure gradient will weaken. Given the poor overlap of stronger winds and lower RH, elevated fire weather is only expected on a localized basis. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1250 PM CDT Mon Sep 04 2023 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... The previous forecast remains on track. Latest guidance continues to show poor spatial and temporal overlap of strong winds and sub-25% RH across the southern/central Plains ahead of and behind a southeastward moving cold front. Isolated thunderstorms along the front are also possible by late afternoon across northwest TX into OK, which may further limit the fire weather threat. While a few dry thunderstorms are possible on the southwestern fringe of the front across west TX, confidence in storm coverage is too limited for highlights. ..Moore.. 09/04/2023 .PREV DISCUSSION... /ISSUED 1256 AM CDT Mon Sep 04 2023/ ...Synopsis... The upper-level trough in the central/northern Plains will continue to the northeast on Tuesday. This trough and an attendant surface cyclone will move into the upper Midwest by the afternoon. A cold front will progress into the central Plains and parts of the southern Plains. ...Northwest Texas into Kansas... Breezy conditions appear probable ahead of and behind the cold front. The strongest winds are expected Tuesday morning, particularly over eastern Kansas where the low-level jet will be strongest. By the afternoon, the surface pressure gradient will weaken. Given the poor overlap of stronger winds and lower RH, elevated fire weather is only expected on a localized basis. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1250 PM CDT Mon Sep 04 2023 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... The previous forecast remains on track. Latest guidance continues to show poor spatial and temporal overlap of strong winds and sub-25% RH across the southern/central Plains ahead of and behind a southeastward moving cold front. Isolated thunderstorms along the front are also possible by late afternoon across northwest TX into OK, which may further limit the fire weather threat. While a few dry thunderstorms are possible on the southwestern fringe of the front across west TX, confidence in storm coverage is too limited for highlights. ..Moore.. 09/04/2023 .PREV DISCUSSION... /ISSUED 1256 AM CDT Mon Sep 04 2023/ ...Synopsis... The upper-level trough in the central/northern Plains will continue to the northeast on Tuesday. This trough and an attendant surface cyclone will move into the upper Midwest by the afternoon. A cold front will progress into the central Plains and parts of the southern Plains. ...Northwest Texas into Kansas... Breezy conditions appear probable ahead of and behind the cold front. The strongest winds are expected Tuesday morning, particularly over eastern Kansas where the low-level jet will be strongest. By the afternoon, the surface pressure gradient will weaken. Given the poor overlap of stronger winds and lower RH, elevated fire weather is only expected on a localized basis. ...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 1230 PM CDT Mon Sep 04 2023 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER MISSISSIPPI VALLEY VICINITY... ...SUMMARY... Isolated severe storms -- accompanied primarily by hail/wind potential -- will be possible on Tuesday across parts of the Upper Mississippi Valley. ...Upper Mississippi Valley... Thunderstorms -- and some hail risk -- may be ongoing at the start of the period across portions of the eastern Dakotas and northwestern Minnesota, near an advancing cold front and associated short-wave advancing eastward across the Plains. Convection should gradually increase through the day across the Minnesota vicinity as daytime heating fosters moderate warm-sector destabilization. As stronger mid-level southwesterlies associated with the advancing trough spread into/atop the region, isolated stronger storms are forecast to evolve during the afternoon, with a few rotating storms possibly evolving. Large hail and damaging winds will be the primary risks, though a brief tornado cannot be ruled out. With time, some upscale growth of convection into an MCS may occur, spreading eastward into northern Wisconsin and possibly western Upper Michigan into the overnight hours. ..Goss.. 09/04/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Mon Sep 04 2023 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER MISSISSIPPI VALLEY VICINITY... ...SUMMARY... Isolated severe storms -- accompanied primarily by hail/wind potential -- will be possible on Tuesday across parts of the Upper Mississippi Valley. ...Upper Mississippi Valley... Thunderstorms -- and some hail risk -- may be ongoing at the start of the period across portions of the eastern Dakotas and northwestern Minnesota, near an advancing cold front and associated short-wave advancing eastward across the Plains. Convection should gradually increase through the day across the Minnesota vicinity as daytime heating fosters moderate warm-sector destabilization. As stronger mid-level southwesterlies associated with the advancing trough spread into/atop the region, isolated stronger storms are forecast to evolve during the afternoon, with a few rotating storms possibly evolving. Large hail and damaging winds will be the primary risks, though a brief tornado cannot be ruled out. With time, some upscale growth of convection into an MCS may occur, spreading eastward into northern Wisconsin and possibly western Upper Michigan into the overnight hours. ..Goss.. 09/04/2023 Read more

WW 0664 Status Updates
STATUS REPORT ON WW 664 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 45 WSW U31 TO U31 TO 35 NNE U31 TO 35 ESE BAM TO 5 NW EKO TO 45 N EKO TO 40 NE OWY. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 2077 ..JEWELL..09/03/23 ATTN...WFO...LKN...VEF...SLC... STATUS REPORT FOR WS 664 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NVC007-011-015-017-023-033-032340- NV . NEVADA COUNTIES INCLUDED ARE ELKO EUREKA LANDER LINCOLN NYE WHITE PINE UTC003-005-011-023-027-029-033-035-045-049-057-032340- UT . UTAH COUNTIES INCLUDED ARE BOX ELDER CACHE DAVIS JUAB MILLARD MORGAN RICH SALT LAKE TOOELE UTAH WEBER THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL Read more

WW 664 SEVERE TSTM NV UT 031930Z - 040300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 664 NWS Storm Prediction Center Norman OK 1230 PM PDT Sun Sep 3 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Central and Eastern Nevada Western and Northern Utah * Effective this Sunday afternoon and evening from 1230 PM until 800 PM PDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Strong to severe thunderstorms will continue to increase across the region, supported by a very moist air mass and strong winds aloft ahead of an approaching upper-level system. The severe thunderstorm watch area is approximately along and 120 statute miles east and west of a line from 85 miles north of Wendover UT to 80 miles east southeast of Tonopah NV. 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 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 23030. ...Guyer Read more

MD 2077 CONCERNING SEVERE THUNDERSTORM WATCH 664...665... FOR FAR NORTHEAST NEVADA AND NORTHERN UTAH INTO EASTERN IDAHO
Mesoscale Discussion 2077 NWS Storm Prediction Center Norman OK 0520 PM CDT Sun Sep 03 2023 Areas affected...far northeast Nevada and northern Utah into eastern Idaho Concerning...Severe Thunderstorm Watch 664...665... Valid 032220Z - 040145Z The severe weather threat for Severe Thunderstorm Watch 664, 665 continues. SUMMARY...Strong to severe storms will move out of Utah and into eastern Idaho producing a few damaging gusts or marginal hail. DISCUSSION...A cluster of storms is currently moving rapidly northward across Box Elder County UT, with indications of severe gust and marginal hail potential. Visible imagery shows an area of relatively better heating extending into eastern ID, with is also within the surface theta-e plume. Given the meridional deep-layer shear vector orientation and values over 40 kt, the severe threat is expected to increase through this corridor over the next few hours. ..Jewell.. 09/03/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...RIW...SLC...PIH...LKN... LAT...LON 41471415 41751408 42001361 42281323 43031272 43711245 44091235 44311202 44371165 44221111 43461085 42161131 41761155 41371196 41241239 41141292 41121329 41071362 41111389 41471415 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0312 PM CDT Sun Sep 03 2023 Valid 051200Z - 111200Z The potential for widespread critical fire weather conditions appears limited through the extended period, though regional concerns may emerge across the southern Plains on D3/Tuesday. Long-range guidance depicts reasonably good agreement in the evolution of the synoptic regime through the middle/late work week as upper-level ridging becomes re-established over northern Mexico into NM/TX. This will displace stronger mid-level flow over the northern CONUS with sporadic rain chances across the Rockies into the central and eastern U.S. Ensemble guidance shows low probability for wetting rainfall and warm temperatures across TX into the Four Corners region, which should facilitate fuel drying through the week. However, the building ridge will also limit the potential for strong pressure-gradient winds with few strong wind signals noted in ensemble guidance after D3/Tuesday. Additionally, fuels to the west of the Plains likely require several days of drying in order to support a robust fire weather threat. While localized fire weather concerns may emerge across parts of the southern Plains and perhaps northern MT (where fuels are also fairly dry), confidence in critical fire weather conditions for any one day is fairly low. ...D3/Tuesday - Southern High Plains... A cold front is expected to push southeast across KS into OK and perhaps far north TX through D3/Tuesday. Breezy winds immediately ahead and behind the front may support a few hours of elevated fire weather conditions from north TX into northeast OK and eastern KS. However, deterministic solutions hint at a displacement of the stronger winds across KS with the hotter/drier conditions across TX/OK. Ensemble guidance supports this idea with relatively low probabilities for combined 15+ mph winds and sub-25% RH across this region. While confidence in the overall threat is limited for this outlook, highlights may be needed in subsequent updates if guidance trends towards a better overlap of dry/windy conditions. ..Moore.. 09/03/2023 ...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 0300 PM CDT Sun Sep 03 2023 Valid 032000Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE GREAT BASIN/INTERMOUNTAIN WEST... ...SUMMARY... Thunderstorms capable of severe wind gusts and hail remain possible across much of the Great Basin and Intermountain West this afternoon and evening, especially across parts of Nevada and Utah into southeast Idaho. ...20Z Update... The Slight Risk has been expanded slightly into a larger part of southeast ID and far western WY. Also, a small 15% hail area has been added where somewhat greater potential for supercells is expected later this afternoon. Otherwise, no changes have been made. Thunderstorms will continue to gradually increase in coverage and intensity this afternoon from NV into northwest UT and southern ID, as a seasonably strong mid/upper-level shortwave trough moves across the northern Great Basin. Moderate deep-layer shear and sufficient instability will continue to support the potential for organized storm clusters and a few supercells, with a threat of strong/severe gusts and some hail. See the previous discussion below for more information. Also refer to MCD 2076, WW 664, and WW 665 for more information regarding the short-term threat. ..Dean.. 09/03/2023 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Sep 03 2023/ ...Great Basin/Intermountain West... An upper trough centered over northern California early today will continue to spread east-northeastward over the Great Basin. Preceding the upper trough, 12z observed soundings from locations such as Elko NV, Boise ID, and Salt Lake City UT sampled a very moist air mass with Precipitable Water values generally ranging from 0.80-1.25 inches. Some stronger thunderstorms are already evident early today across western Nevada, and a further increase in coverage and intensity is likely regionally into the afternoon as the boundary layer heats, with plentiful cloud breaks noted across eastern Nevada into Utah this morning. Hail and strong/severe-caliber winds will be possible across a broad region, but the most organized and sustained storms, including some supercells, should occur across the eastern half of Nevada into western/north Utah and possibly southeast Idaho where effective shear should be around 35-45 kt. ...North Texas... Thunderstorms should increase this afternoon, at least in a widely scattered sense, on the immediate eastern periphery of an upper low centered across north Texas. Vertical shear will be weak, and overall buoyancy will be limited as compared to typical summertime standards. However, a pocket of cool mid-level temperatures (around -10C at 500 mb) could support some stronger (low-topped but high-based) storms as the boundary layer heats. A few storms could produce severe-caliber wind gusts. Read more

WW 0665 Status Updates
STATUS FOR WATCH 0665 HAS NOT BEEN ISSUED YET Read more

WW 665 SEVERE TSTM ID WY 031955Z - 040400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 665 NWS Storm Prediction Center Norman OK 155 PM MDT Sun Sep 3 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southern and Eastern Idaho Western Wyoming * Effective this Sunday afternoon and evening from 155 PM until 1000 PM MDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Scattered large hail events to 1.5 inches in diameter possible SUMMARY...Widely scattered thunderstorms will continue to intensify across the region, potentially including a few supercells given a very moist air mass and strong winds aloft. Storms should become more scattered/numerous by late afternoon and early evening, with continued large hail and severe wind gust potential as storms move northeastward across the region. The severe thunderstorm watch area is approximately along and 70 statute miles east and west of a line from 45 miles north of Jackson WY to 20 miles southwest of Malad City ID. 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 664... AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 24030. ...Guyer Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0117 PM CDT Sun Sep 03 2023 Valid 041200Z - 051200Z The Elevated risk area has been expanded to include portions of western KS, and an isolated dry thunderstorm risk area has been introduced to the TX Panhandle region. Latest forecast guidance continues to show reasonably good agreement in increasing winds across the Plains with high probability for 15+ mph sustained winds from west TX into parts of the upper MS River Valley. Additionally, a slight drying trend has been noted across western KS in most solutions over the past 6-12 hours, which increases confidence in more locations maintaining 20-25% RH. Consequently, the risk areas have been conjoined to include areas of western KS where elevated fire weather conditions appear probable. Recent CAM guidance has also begun to show a stronger signal for very isolated convection across the greater TX Panhandle region Monday afternoon. Forecast thermodynamic profiles still appear only marginally supportive for convection, but feature deep, well-mixed boundary layers conducive for dry lightning. This factor, along with the potential for strong thunderstorm outflows and antecedent dry fuels, supports introducing a dry-thunderstorm risk area. ..Moore.. 09/03/2023 .PREV DISCUSSION... /ISSUED 0130 AM CDT Sun Sep 03 2023/ ...Synopsis... On Monday, the upper-level trough within the Four Corners will continue to move eastward while beginning to lift northward as well. The surface trough will sharpen across the Plains. ...Southern High Plains... Fuels have continued to dry with the hot temperatures and lack of precipitation. Surface winds near the surface trough will increase to 15-20 mph (perhaps locally higher) with some gust potential given stronger flow at 850 mb. RH will fall to 15-20%. There is a weak signal for mid-level convection to occur along the trough. Profiles are not overly conducive to lightning production, so the threat for lightning ignitions appears low at this time. However, gusty outflow winds are still possible from this activity. Fire weather concerns will be elevated for a few hours during the afternoon. ...Missouri Valley Vicinity... Winds are expected to be slightly stronger in the region Monday as compared to Sunday. 15-20 mph will be most common, but locally stronger sustained winds are possible as well as a few gusts. RH will remain the biggest question once again. Areas of 15-25% are possible, but the northward and eastward extents are still uncertain. ...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 1228 PM CDT Sun Sep 03 2023 Valid 041200Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF NORTHWEST SD...SOUTHWEST ND...EXTREME NORTHEAST WY...EXTREME SOUTHEAST MT... ...SUMMARY... Thunderstorms capable of producing isolated to widely scattered severe wind and hail will be possible Monday afternoon and evening across parts of the northern Plains. ...Northern Plains... Multiple rounds of strong to potentially severe thunderstorms will be possible across parts of the northern Plains Monday afternoon/evening, as a mid/upper-level shortwave trough ejects northeastward out of the Intermountain West. Initial diurnal storm development is expected across the higher terrain of WY, which will spread northeastward into an increasingly warm and unstable environment across the Dakotas. Low-level moisture is expected to remain somewhat limited, which will result in a tendency for convection to be relatively high-based, but increasing deep-layer shear will support organized storm structures, including the potential for organized clusters and potentially a few supercells. The greatest coverage of storms is expected near and just north of a frontal zone draped from western SD into southern ND, with a more conditional risk of isolated storm development near a surface low that will be located near the ND/MN/MB border Monday afternoon. Severe gusts may be the most prominent hazard, given the potential for relatively organized and high-based convection. However, any sustained supercells will also pose some hail potential, especially near the front where buoyancy will be maximized. Convection may tend to be more disorganized with southward extent, but strong pre-convective heating/mixing will support a threat of isolated outflow-driven severe gusts into southern SD and western NE. ...AR into southern MO... An upper-level low initially over north TX is forecast to move northeastward toward the Ozarks through the day on Monday. This will result in somewhat colder temperatures aloft and steeper midlevel lapse rates overspreading relatively rich low-level moisture across parts of AR and southern MO. MLCAPE will increase to near or above 2000 J/kg, in conjunction with a modest increase in deep-layer southerly flow east of the upper low track. A few stronger multicell clusters will be possible during the afternoon and evening, posing a threat of isolated damaging gusts and perhaps some hail. ..Dean.. 09/03/2023 Read more