SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Mon Aug 12 2024 Valid 131200Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE EASTERN GREAT BASIN INTO THE NORTHERN/CENTRAL ROCKIES AND ADJACENT HIGH PLAINS...AND ACROSS PARTS OF SOUTH CAROLINA AND VICINITY... ...SUMMARY... Isolated severe thunderstorms appear possible Tuesday across parts of the eastern Great Basin into the northern/central High Plains, as well as portions of South Carolina and vicinity. ...Eastern Great Basin to the Northern/Central High Plains... Upper ridging will remain over much of the Plains on Tuesday, while a mid-level shortwave trough develops northeastward from the interior Pacific Northwest across the northern Rockies and adjacent High Plains. Modest low-level mass response ahead of this shortwave trough should encourage the development/sharpening of a weak surface low and associated lee trough extending southward along much of the length of the northern/central High Plains. Northward advance of low-level moisture is expected across these areas, along and east of the lee trough. Steepened mid-level lapse rates and daytime heating of this moistening airmass should support moderate instability developing by late Tuesday afternoon. Although mid-level flow is not forecast to be overly strong in association with the mid-level shortwave trough, gradual veering and modest strengthening of the wind field with height through mid/upper levels should foster sufficient deep-layer shear for some thunderstorm organization. An isolated threat for hail and severe winds should exist with any robust cores that can develop along the length of the lee trough and subsequently spread eastward Tuesday afternoon through evening. Confidence in a more focused area of severe potential remains too low to include greater severe probabilities at this time. There also appears to be some chance for stronger thunderstorms to occur across the eastern Great Basin into parts of the northern/central Rockies. While low-level moisture will generally be more limited compared to the High Plains, sufficient instability and deep-layer shear to support modestly organized convection are forecast. Isolated hail and strong to severe wind gusts may occur with this high-based activity as it spreads east-northeastward through Tuesday afternoon and early evening. Therefore, the Marginal Risk has been expanded westward to include more of WY, southern MT, eastern ID, and northern/eastern UT based on latest guidance trends. ...South Carolina and Vicinity... As a mid/upper-level trough persists over the eastern states, some enhancement to west-northwesterly winds will occur across parts of the OH/TN Valleys into the Carolinas and Southeast on Tuesday. Deep-layer shear should be strong enough for modestly organized convection. But, poor lapse rates aloft may tend to limit instability to some extent across SC and vicinity Tuesday afternoon. Regardless, confidence has increased that isolated to scattered thunderstorms capable of producing occasionally strong to damaging winds should occur, and a Marginal Risk has been introduced to account for this potential. ..Gleason.. 08/12/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1252 AM CDT Mon Aug 12 2024 Valid 131200Z - 141200Z ...NO CRITICAL AREAS... ...Synopsis... On Tuesday, the upper trough will lift out of the northern Great Basin and into the northern High Plains, all while losing amplitude. While some increase in mid-level winds may occur over the Great Basin, this will not occur until late in the period. At the surface, the pressure pattern will be more disorganized than Monday and stronger winds will likely be diurnally/terrain-driven. ...Nevada... Areas of locally elevated fire weather are possible as RH will still fall to 15-20% during the afternoon. Slightly stronger winds appear possible in southern Nevada, but fuels are also less receptive than farther north. Sustained elevated conditions are not currently expected. ...Central Idaho... With the mid-level trough moving through early in the period, mid/upper-level cloud cover will be possible. This may impact destabilization enough to reduce potential storm coverage during the afternoon. Should storms occur, some could be dry. Confidence in coverage is too low for highlights. ..Wendt.. 08/12/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1242 AM CDT Mon Aug 12 2024 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL ROCKIES/HIGH PLAINS REGION AND COASTAL CAROLINAS... ...SUMMARY... A few marginally severe gusts are possible with convection across portions of the CONUS this afternoon. However, organized severe is not currently anticipated. ...Rockies/Central High Plains Region... Upper anticyclone is expected to refocus itself over north TX by the end of the period as west coast troughing helps to nudge the Rockies ridge east a bit. Latest model guidance suggests several weak disturbances will eject across the Great Basin toward the central Rockies, and these features should encourage convection during the afternoon/evening. While mid-level flow is not forecast to be particularly strong, boundary-layer heating across the interior Rockies region will contribute to adequate buoyancy for robust convection. Forecast soundings across UT into eastern ID favor gusty winds with afternoon/evening convection as low-level lapse rates will be steep. Downstream along the CO Front Range, southeasterly low-level flow will maintain upslope convergence into the higher terrain and scattered thunderstorms will develop as convective temperatures are breached, likely by 21-22z. This activity will spread/propagate toward the High Plains aided by 25kt 500mb westerly flow. LLJ should increase across the TX Panhandle into southwest KS during the evening and this will encourage eastward propagation across the central High Plains during the overnight hours. ...Coastal Carolinas... Southern influence of eastern US trough will affect the Carolinas later today. Models suggest 20-30kt mid-level flow will extend across a frontal zone that will be draped over coastal regions. Scattered thunderstorms should develop along this boundary by early afternoon then propagate toward and off the coast by early evening. Marginally severe gusts could be noted with the strongest storms. ..Darrow/Wendt.. 08/12/2024 Read more

MD 1884 CONCERNING SEVERE THUNDERSTORM WATCH 619... FOR WEST-CENTRAL NEBRASKA...NORTHWEST KANSAS
Mesoscale Discussion 1884 NWS Storm Prediction Center Norman OK 0747 PM CDT Sun Aug 11 2024 Areas affected...West-central Nebraska...Northwest Kansas Concerning...Severe Thunderstorm Watch 619... Valid 120047Z - 120245Z The severe weather threat for Severe Thunderstorm Watch 619 continues. SUMMARY...A threat for isolated large hail and severe wind gusts will likely continue for an hour or two, before becoming marginal. No additional weather watch issuance is expected. DISCUSSION...Mosaic radar imagery shows scattered to widely scattered strong to severe storms located from north-central Nebraska into far northwest Kansas. The storms are located to the east of an axis of moderate instability, where the RAP has MLCAPE in the 1000 to 2000 J/kg range. This, combined with moderate deep-layer shear, evident on regional WSR-88D VWPs, will continue to be favorable for severe storms over the next couple of hours. Severe wind gusts and isolated large hail will be the primary threats. However, the storms will move eastward into the central Plains, where instability is weaker and a capping inversion is present. This will result in a gradual weakening trend during the mid to late evening. ..Broyles.. 08/12/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GID...LBF...DDC...GLD... LAT...LON 42180005 41940074 41300108 39750174 39120182 38760162 38660110 38730055 39220024 41709934 42180005 Read more

WW 0619 Status Updates
STATUS REPORT ON WW 619 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 NNE AKO TO 30 S VTN. ..BROYLES..08/12/24 ATTN...WFO...GLD...BOU...LBF... STATUS REPORT FOR WS 619 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC017-063-095-115-120240- CO . COLORADO COUNTIES INCLUDED ARE CHEYENNE KIT CARSON PHILLIPS SEDGWICK KSC109-181-193-199-120240- KS . KANSAS COUNTIES INCLUDED ARE LOGAN SHERMAN THOMAS WALLACE NEC029-091-101-117-135-120240- NE . NEBRASKA COUNTIES INCLUDED ARE CHASE HOOKER KEITH MCPHERSON PERKINS Read more

WW 619 SEVERE TSTM CO KS NE 112040Z - 120300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 619 NWS Storm Prediction Center Norman OK 240 PM MDT Sun Aug 11 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northeast Colorado Northwest Kansas Western Nebraska * Effective this Sunday afternoon and evening from 240 PM until 900 PM MDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2 inches in diameter possible Scattered damaging wind gusts to 70 mph possible A tornado or two possible SUMMARY...Thunderstorms are strengthening across the Nebraska panhandle and northeast Colorado. This activity will spread eastward through the afternoon, posing a risk of large hail and damaging wind gusts. The severe thunderstorm watch area is approximately along and 50 statute miles east and west of a line from 75 miles north northwest of Mullen NE to 40 miles south of Burlington CO. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU9). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 618... 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 500. Mean storm motion vector 29025. ...Hart Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 PM CDT Sun Aug 11 2024 Valid 120100Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Scattered severe thunderstorms will continue across parts of the central High Plains early this evening. Other storms with strong wind gusts may affect parts of Utah, northern Arizona, and western Colorado for the next few hours. ...01z Update... Early-evening water-vapor imagery depicts a well-defined short-wave trough digging southeast across the High Plains of SD/NE. This feature is forecast to approach the mid MO Valley by sunrise. Scattered convection developed in response to the short wave across SD/NE with more isolated activity noted into eastern CO. Over the last hour or so, the primary corridor of robust updrafts is focusing along an instability axis that extends from western NE into western KS. These storms will continue to propagate south along this zone of stronger buoyancy, especially as northwesterly flow dominates the High Plains in the wake of the short wave. Boundary-layer airmass over much of the lower central Plains is not particularly unstable so convection is expected to weaken as it advances atop this cooler, more stable air. For the next few hours hail/wind could accompany the storms from north of LBF to south of GLD. Gusty winds may also be noted with convection across the Great Basin into western CO for the next few hours. Numerous showers/thunderstorms have developed across southern UT/northern AZ into western CO. 00z sounding from GJT exhibits around 400 J/kg MLCAPE with steep 0-3km lapse rates. After sunset low-levels should cool and the prospects for severe gusts should diminish. ..Darrow.. 08/12/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 PM CDT Sun Aug 11 2024 Valid 120100Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Scattered severe thunderstorms will continue across parts of the central High Plains early this evening. Other storms with strong wind gusts may affect parts of Utah, northern Arizona, and western Colorado for the next few hours. ...01z Update... Early-evening water-vapor imagery depicts a well-defined short-wave trough digging southeast across the High Plains of SD/NE. This feature is forecast to approach the mid MO Valley by sunrise. Scattered convection developed in response to the short wave across SD/NE with more isolated activity noted into eastern CO. Over the last hour or so, the primary corridor of robust updrafts is focusing along an instability axis that extends from western NE into western KS. These storms will continue to propagate south along this zone of stronger buoyancy, especially as northwesterly flow dominates the High Plains in the wake of the short wave. Boundary-layer airmass over much of the lower central Plains is not particularly unstable so convection is expected to weaken as it advances atop this cooler, more stable air. For the next few hours hail/wind could accompany the storms from north of LBF to south of GLD. Gusty winds may also be noted with convection across the Great Basin into western CO for the next few hours. Numerous showers/thunderstorms have developed across southern UT/northern AZ into western CO. 00z sounding from GJT exhibits around 400 J/kg MLCAPE with steep 0-3km lapse rates. After sunset low-levels should cool and the prospects for severe gusts should diminish. ..Darrow.. 08/12/2024 Read more

WW 0618 Status Updates
STATUS REPORT ON WW 618 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 ENE CDR TO 40 NW PHP. ..BROYLES..08/11/24 ATTN...WFO...UNR... STATUS REPORT FOR WS 618 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS SDC007-055-071-093-095-102-103-121-112340- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE BENNETT HAAKON JACKSON MEADE MELLETTE OGLALA LAKOTA PENNINGTON TODD 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

MD 1883 CONCERNING SEVERE THUNDERSTORM WATCH 618...619... FOR FAR SOUTHWEST SOUTH DAKOTA...WESTERN NEBRASKA...NORTHEAST COLORADO...FAR NORTHWEST KANSAS
Mesoscale Discussion 1883 NWS Storm Prediction Center Norman OK 0518 PM CDT Sun Aug 11 2024 Areas affected...Far Southwest South Dakota...Western Nebraska...Northeast Colorado...Far Northwest Kansas Concerning...Severe Thunderstorm Watch 618...619... Valid 112218Z - 120015Z The severe weather threat for Severe Thunderstorm Watch 618, 619 continues. SUMMARY...A threat for large hail and severe wind gusts will continue across the central Plains over the next few hours. There is a localized potential for hail over 2 inches in diameter. DISCUSSION...Water vapor imagery shows northwest flow over much of the central U.S., with a subtle shortwave trough moving through the central High Plains. At the surface, a quasi-stationary front is located from southwestern South Dakota extending southward into far eastern Colorado. Scattered to widely scattered thunderstorms are ongoing just to the east of the boundary. The RAP suggests that the storms are near an axis of instability, with MLCAPE just to the east of the front estimated to be in the 1000 to 2000 J/kg range. In addition, regional WSR-88D VWPs also show moderate deep-layer shear in place across much of the central High Plains. 0-6 km shear appears to be in the 40 to 50 knot range along and near the instability axis. This will continue to support supercell development over the next few hours. Severe wind gusts and isolated large hail will be the primary threats. Hailstones of greater than 2 inches in diameter will be possible locally, mainly over far northeast Colorado and far northwest Kansas, where the combination of instability and shear appears to be maximized. ..Broyles.. 08/11/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...UNR...GLD...BOU... LAT...LON 41640244 40420263 39900254 39570221 39510183 39620134 40040105 41390060 42350032 42910030 43230057 43410129 43350191 43170218 42840231 41640244 Read more

WW 0618 Status Updates
STATUS REPORT ON WW 618 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 ENE CDR TO 40 NW PHP. ..BROYLES..08/11/24 ATTN...WFO...UNR... STATUS REPORT FOR WS 618 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS SDC007-055-071-093-095-102-103-121-112340- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE BENNETT HAAKON JACKSON MEADE MELLETTE OGLALA LAKOTA PENNINGTON TODD 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 618 SEVERE TSTM SD WY 111830Z - 120100Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 618 NWS Storm Prediction Center Norman OK 1230 PM MDT Sun Aug 11 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southwest South Dakota Northeast Wyoming * Effective this Sunday afternoon and evening from 1230 PM until 700 PM MDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2 inches in diameter possible Scattered damaging wind gusts to 70 mph possible A tornado or two possible SUMMARY...Thunderstorms will increase in coverage and intensity through the afternoon across the watch area. A few severe storms are expected, capable of large hail and damaging wind gusts. The severe thunderstorm watch area is approximately along and 40 statute miles north and south of a line from 50 miles west of Rapid City SD to 65 miles southeast of Philip SD. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU8). 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 500. Mean storm motion vector 28030. ...Hart Read more

WW 0619 Status Updates
STATUS REPORT ON WW 619 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..BROYLES..08/11/24 ATTN...WFO...GLD...BOU...LBF... STATUS REPORT FOR WS 619 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC017-063-075-095-115-121-125-112240- CO . COLORADO COUNTIES INCLUDED ARE CHEYENNE KIT CARSON LOGAN PHILLIPS SEDGWICK WASHINGTON YUMA KSC023-109-153-181-193-199-112240- KS . KANSAS COUNTIES INCLUDED ARE CHEYENNE LOGAN RAWLINS SHERMAN THOMAS WALLACE NEC005-029-031-049-057-069-075-087-091-101-117-135-161-112240- NE . NEBRASKA COUNTIES INCLUDED ARE ARTHUR CHASE CHERRY DEUEL DUNDY GARDEN Read more

WW 619 SEVERE TSTM CO KS NE 112040Z - 120300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 619 NWS Storm Prediction Center Norman OK 240 PM MDT Sun Aug 11 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northeast Colorado Northwest Kansas Western Nebraska * Effective this Sunday afternoon and evening from 240 PM until 900 PM MDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2 inches in diameter possible Scattered damaging wind gusts to 70 mph possible A tornado or two possible SUMMARY...Thunderstorms are strengthening across the Nebraska panhandle and northeast Colorado. This activity will spread eastward through the afternoon, posing a risk of large hail and damaging wind gusts. The severe thunderstorm watch area is approximately along and 50 statute miles east and west of a line from 75 miles north northwest of Mullen NE to 40 miles south of Burlington CO. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU9). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 618... 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 500. Mean storm motion vector 29025. ...Hart Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0344 PM CDT Sun Aug 11 2024 Valid 131200Z - 191200Z The potential for widespread critical fire weather conditions remains limited for the upcoming work week and into next weekend. The upper-level shortwave trough currently deepening across the Pacific Northwest is forecast to propagate into the central CONUS by the start of the forecast period. In its wake, a highly amplified upper ridge will likely become established over the central Plains/Rockies with mean troughing along the West Coast. This synoptic pattern will favor rain/thunderstorm chances for much of the country with the exception of central TX and much of NV and CA. ...Nevada and California... Cooling temperatures across NV/CA should modulate fire concerns to some degree, but the mean trough along the West Coast will favor the passage of embedded shortwave troughs across the region. Such features have inherent low predictability at this range, but will support breezy conditions over a region with dry fuels. Consequently, localized fire weather concerns are possible later this week, but confidence remains low for any particular day. ...Pacific Northwest... Deterministic models and ensemble guidance continue to show considerable spread regarding precipitation totals across the Pacific Northwest for the upcoming work week. The typically drier GFS/GEFS solutions hint at the potential for thunderstorms, including dry thunderstorms, around mid-week, most likely on D6/Thursday afternoon. Ensembles hint at the potential for wetting rainfall, so confidence in the dry thunderstorm threat is too low for highlights, but given recent lightning-related fire starts, trends will be monitored. ...Central Texas... The probability for widespread wetting rainfall appears limited through the end of the upcoming work week across central to western TX as the upper-level ridge begins to build. Likewise, temperatures are forecast to climb back into the low 100s, which should act to cure fine fuels. Weak pressure gradient winds under the ridge should limit fire concerns, but trends in wind speeds and fuels will be monitored. ..Moore.. 08/11/2024 ...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 0252 PM CDT Sun Aug 11 2024 Valid 112000Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Scattered severe thunderstorms are expected across parts of the central High Plains this afternoon into the early evening. Other storms with strong wind gusts may affect parts of Utah, northern Arizona, and western Colorado. Expanded the Marginal and Slight Risk farther north into South Dakota where severe thunderstorm watch 618 is in effect and severe storms are ongoing. Otherwise, no changes were necessary. For more discussion on the watch 618, see MCD 1879 and for discussion farther south where storms are starting to develop in northeastern Colorado and vicinity, see MCD 1880. A few stronger storms have developed in Upstate New York. However, given the weak buoyancy, expect any severe threat to remain marginal and isolated. ..Bentley.. 08/11/2024 .PREV DISCUSSION... /ISSUED 1111 AM CDT Sun Aug 11 2024/ ...High Plains... Morning water vapor loops show a shortwave trough and associated mid-level speed max moving across WY. This feature and its associated lift will move into the High Plains this afternoon, promoting widely scattered thunderstorm development. Forecast soundings from southwest SD southward into western NE/KS show steep mid-level lapse rates, considerable deep layer shear, and pockets of MLCAPE of 1500-2500 J/kg. This will be sufficient for supercell structures capable of large hail and eventually damaging winds during the late afternoon and evening. ...Great Basin... Ample mid-level moisture is present today across much of southern UT, northern AZ, and western CO. Strong heating should lead to scattered afternoon thunderstorms throughout the region. Steep low/mid level lapse rates and sufficient westerly flow aloft will pose a risk of damaging winds in the strongest cores. Read more

MD 1879 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS OF SOUTHWESTERN SD AND NORTHWESTERN NE
Mesoscale Discussion 1879 NWS Storm Prediction Center Norman OK 0117 PM CDT Sun Aug 11 2024 Areas affected...Portions of southwestern SD and northwestern NE Concerning...Severe potential...Watch possible Valid 111817Z - 112015Z Probability of Watch Issuance...40 percent SUMMARY...Portions of southwestern South Dakota into northwestern Nebraska are being monitored for a possible Severe Thunderstorm Watch. DISCUSSION...Isolated to widely scattered thunderstorms are evolving over far northeastern WY and over the Black Hills early this afternoon -- likely aided by ascent preceding a midlevel shortwave trough (and associated MCV) tracking eastward across southwest MT, and heating over the higher terrain. Continue diurnal heating/destabilization amid middle/upper 50s to lower 60s dewpoints will continue to erode boundary-layer inhibition and contribute to 500-1000 J/kg MLCAPE. This, coupled with long/mostly straight hodographs (around 40-45 kt of effective shear), will support a gradual increase in thunderstorm intensity/organization through the afternoon. The primary concern with any initial semi-discrete/splitting supercell structures is large hail (generally 1.5-1.75 inches) and locally severe gusts. Thunderstorms will generally track southeastward into northwestern Nebraska through the afternoon, where continued heating will support a corridor of sufficient (albeit weak) surface-based instability for a continued severe risk. There is uncertainty on the overall coverage of severe thunderstorms across the area, and the need for a watch is uncertain. ..Weinman/Hart.. 08/11/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...UNR...CYS... LAT...LON 43810397 44330401 44510388 44650348 44600304 44410225 44060146 43400067 42800059 42200073 41920133 41770240 41950340 42380361 43370387 43810397 Read more

MD 1880 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR NORTHEAST CO...SOUTHWEST NE...FAR SOUTHEAST WY...AND FAR NORTHWEST KS
Mesoscale Discussion 1880 NWS Storm Prediction Center Norman OK 0217 PM CDT Sun Aug 11 2024 Areas affected...Northeast CO...southwest NE...far southeast WY...and far northwest KS Concerning...Severe potential...Watch possible Valid 111917Z - 112115Z Probability of Watch Issuance...40 percent SUMMARY...The potential for a few severe thunderstorms capable of producing large hail and severe wind gusts will increase over the next few hours. A watch may eventually be needed for parts of the area. DISCUSSION...Boundary-layer cumulus is gradually deepening and expanding along an east/west-oriented confluence zone extending from southeastern WY into the southwestern NE Panhandle -- and isolated convective initiation is underway here. Additional attempts at development are ongoing along a lee trough extending northward across southwest WY. Given this focused mesoscale ascent and continued diurnal heating of a relatively moist boundary layer (middle/upper 50s to lower 60s dewpoints), current expectation is for a few thunderstorms to evolve/intensify during the next couple hours before spreading east-southeastward. The CYS VWP is sampling a unidirectional westerly shear profile (around 35 kt of 0-6 km shear), and this will continue increasing to around 40-50 kt with the approach of a midlevel jet. As a result, a few thunderstorms may intensify into organized clusters and/or supercell structures, posing a risk of large hail (generally up to 2 inches in diameter) and severe wind gusts to around 70 mph. Modest large-scale ascent and substantial MLCINH with eastward extent cast uncertainty on the overall coverage of the severe threat, though trends are being monitored for a possible watch this afternoon. ..Weinman/Hart.. 08/11/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...GLD...BOU...CYS... LAT...LON 40690381 40960413 41270421 41630423 41970412 42180382 42190335 41670208 40830143 39410123 39000162 38940247 39190294 40240355 40690381 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0208 PM CDT Sun Aug 11 2024 Valid 121200Z - 131200Z ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEVADA... A critical risk area has been introduced to portions of northwest NV. Recent deterministic solutions hint that the primary axis of the upper-level trough (and attendant mid-level cold front) should be impinging along/just east of the northern Sierra around peak heating Monday afternoon. Stronger mid-level flow associated with this feature should bolster downslope winds, resulting in sustained winds above 20 mph with gusts upwards of 30-35 mph possible. This trend is reflected in recent ensemble guidance, which shows high (60+ %) probability for winds over 20 mph. Given antecedent dry fuels and RH values in the low teens, a Critical risk area appears warranted. Additionally, confidence in thunderstorm development has increased for late Monday afternoon into early Tuesday morning as the upper trough deepens and shifts east towards the northern Rockies. Forecast soundings suggest a mixture of wet/dry thunderstorms is most probable, but recent lightning starts in the region under similar thermodynamic regimes suggest that any isolated convection will pose a fire weather concern. ..Moore.. 08/11/2024 .PREV DISCUSSION... /ISSUED 1258 AM CDT Sun Aug 11 2024/ ...Synopsis... A compact shortwave trough will pivot northeastward into the northern Great Basin on Monday. This feature will push a surface boundary into the Northwest. Dry and windy conditions are most likely ahead of the surface boundary across a large portion of Nevada into southern Idaho. Along with a stronger pressure gradient, mid-level winds will also be enhanced with the trough overhead leading to stronger gusts as well. Winds will reach 15-20 mph with some local areas of 20-25 mph. RH will fall into the 10-15% by the afternoon. Elevated fire weather is expected. Forcing for ascent in the Northwest will be relatively weak as the trough will be displaced to the south. There is some potential for isolated thunderstorms developing in central/eastern Oregon. Storm motions would be fast enough that some of this activity could be dry if it develops, but confidence in that scenario is low. ...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 0208 PM CDT Sun Aug 11 2024 Valid 121200Z - 131200Z ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEVADA... A critical risk area has been introduced to portions of northwest NV. Recent deterministic solutions hint that the primary axis of the upper-level trough (and attendant mid-level cold front) should be impinging along/just east of the northern Sierra around peak heating Monday afternoon. Stronger mid-level flow associated with this feature should bolster downslope winds, resulting in sustained winds above 20 mph with gusts upwards of 30-35 mph possible. This trend is reflected in recent ensemble guidance, which shows high (60+ %) probability for winds over 20 mph. Given antecedent dry fuels and RH values in the low teens, a Critical risk area appears warranted. Additionally, confidence in thunderstorm development has increased for late Monday afternoon into early Tuesday morning as the upper trough deepens and shifts east towards the northern Rockies. Forecast soundings suggest a mixture of wet/dry thunderstorms is most probable, but recent lightning starts in the region under similar thermodynamic regimes suggest that any isolated convection will pose a fire weather concern. ..Moore.. 08/11/2024 .PREV DISCUSSION... /ISSUED 1258 AM CDT Sun Aug 11 2024/ ...Synopsis... A compact shortwave trough will pivot northeastward into the northern Great Basin on Monday. This feature will push a surface boundary into the Northwest. Dry and windy conditions are most likely ahead of the surface boundary across a large portion of Nevada into southern Idaho. Along with a stronger pressure gradient, mid-level winds will also be enhanced with the trough overhead leading to stronger gusts as well. Winds will reach 15-20 mph with some local areas of 20-25 mph. RH will fall into the 10-15% by the afternoon. Elevated fire weather is expected. Forcing for ascent in the Northwest will be relatively weak as the trough will be displaced to the south. There is some potential for isolated thunderstorms developing in central/eastern Oregon. Storm motions would be fast enough that some of this activity could be dry if it develops, but confidence in that scenario is low. ...Please see www.spc.noaa.gov/fire for graphic product... Read more