Scattered strong to severe thunderstorms impacted portions of southeast Wyoming from the mid afternoon through the early evening hours on 6/30, producing several instances of large hail in excess of one inch in diameter as well as wind gusts between 60 and 70 MPH. Most notably, a cluster of intense thunderstorms tracked across central Laramie County roughly between 7 PM and 9 PM MDT, producing…
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS CYS wrote it up.
Scattered strong to severe thunderstorms impacted portions of southeast Wyoming from the mid afternoon through the early evening hours on 6/30, producing several instances of large hail in excess of one inch in diameter as well as wind gusts between 60 and 70 MPH. Most notably, a cluster of intense thunderstorms tracked across central Laramie County roughly between 7 PM and 9 PM MDT, producing 70 to 80 MPH wind gusts and reportedly damaging several outbuildings in the northern outskirts of Cheyenne.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Cheyenne, WY wrote its last area forecast discussion before the first event at Jun 30, 10:55 AM MST, 2 hours 41 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Cheyenne WY 1155 AM MDT Sun Jun 30 2024 .KEY MESSAGES... - A few strong to severe thunderstorms this afternoon and evening. Maybe better chances for severe thunderstorms Monday afternoon and evening. - Cooler week ahead before strong ridge and toasty temperatures return for the weekend. && .SHORT TERM /THROUGH TUESDAY/... Issued at 300 AM MDT Sun Jun 30 2024 Frontal boundary lays along a line from northeast New Mexico...north along the front range to Laramie and eventually north central Wyoming this morning. Southeasterly low level winds have raised dewpoints this morning east of this front. Seeing mid 50 dewpoints in the Panhandle so far this morning with low 50s here at Cheyenne. West of the front...dewpoints in the 40s being reported across Carbon County. Dilemma of the day will be whether severe storms are going to form or not. Looks like the Panhandle stays pretty capped through 00Z today. Towards 00Z...low level capping inversion finally break...with GFS MUCAPE increasing to around 1500 J/KG over Sidney. NAM MUCAPE more unstable with a narrow band of 2000 J/KG developing near the Wyoming/Nebraska state line. HRRR/RAP simulated radar showing storms developing over the Laramie Range around the 19Z to 20Z timeframe...drifting eastward. Certainly possible for some of these storms to become supercells. Not the greatest environment...but can't rule out a few severe storms. Large hail and strong downburst winds will be the primary hazards with these storms. Better day Monday for storms as upper shortwave tracks across the CWA and front gets forced east. Northern Panhandle seeing much better instability with MUCAPE near 2500 J/KG Monday afternoon. Much drier Tuesday as westerly winds return to the area. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Issued at 111 AM MDT Sun Jun 30 2024 A cooler, active week is in store for southeast Wyoming and western Nebraska. Upper-level troughing turns upper-level winds northwesterly for Wednesday. Northwesterly flow will usher in cooler air in the region, but not without the threat for strong to severe thunderstorms. Southerly surface flow develops Wednesday, advecting in additional moisture from the Gulf of Mexico ahead of an incoming cold front. The GFS and ECMWF are both on board with a strong dryline developing off the Laramie Range Wednesday afternoon, but the exact position of this boundary is uncertain. Right now, it looks to set up along the Wyoming/Nebraska border, bringing the best storm chances to the Panhandle, with southeast Wyoming missing out once more. However, a slight westerly shift of this dryline will drastically change the output, with much of southeast Wyoming experiencing an increased chance for showers and thunderstorms. At this time, kept PoPs confined mostly to the Panhandle with low end values, around 25-40%. This setup will continue to be monitored as northwest flow tends to produce ample convection to the CWA. Westerly, upper-level flow returns to the region for Thursday through the end of the work week. Relatively benign weather is expected for the latter half of the week, with only slight chances for precipitation in portions of the Panhandle. The cold front that passes through Wednesday will drop temperatures back into the 70s and 80s for Thursday and Friday. Model disagreement returns for the weekend, with the previously advertised ridge now stuck over the Pacific Ocean just off the coast of California for the weekend. Despite this, 700mb temperatures will increase back into the 10-15C range and surface temperatures return to the 80s and 90s once more. Little to no precipitation chances exist at this time for Friday and Saturday, with significant model disagreement in play for Sunday. Kept temperatures for Sunday near the NBM, as the GFS suggests 700mb temperatures in the single digits, whereas the ECMWF keeps 700mb temperatures around 15-16C. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1148 AM MDT Sun Jun 30 2024 The main aviation concern today will be scattered showers and thunderstorms currently developing in Wyoming. Multiple rounds of showers/storms will be possible this afternoon, spreading into Nebraska in the late afternoon and evening. Storms will probably struggle after moving east of the WY/NE border, so confidence is lower that they will make it to KCDR, KAIA, and KSNY. Where confidence is higher, added TEMPO groups for VIS reductions and gusty/erratic winds during the most likely time period for impacts. Storms may also bring hail. Activity should last well into the evening hours, and possibly after midnight in the NE panhandle and near KRWL. Low clouds may creep into the eastern panhandle late tonight into early Monday morning. MVFR to IFR CIGs are possible for the High Plains terminals, but confidence is highest for this occurring at KAIA and KSNY. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && SHORT TERM...GCC LONG TERM...AM AVIATION...MN
Hazardous Weather Outlook National Weather Service Cheyenne WY 719 AM MDT Sun Jun 30 2024 NEZ002-003-019>021-054-055-095-096-WYZ101>119-011330- Dawes County-Box Butte County-Scotts Bluff County-Banner County- Morrill County-Kimball County-Cheyenne County- Northern Sioux County-Southern Sioux County- Converse County Lower Elevations-Niobrara County- North Laramie Range-Ferris/Seminoe/Shirley Mountains- Shirley Basin-Central Laramie Range and Southwest Platte County- East Platte County-Goshen County-Central Carbon County- North Snowy Range Foothills-Southwest Carbon County- Sierra Madre Range-Upper North Platte River Basin-Snowy Range- Laramie Valley-South Laramie Range-South Laramie Range Foothills- Central Laramie County-East Laramie County- 719 AM MDT Sun Jun 30 2024 This hazardous weather outlook is for portions of panhandle Nebraska...east central Wyoming...south central Wyoming and southeast Wyoming. .DAY ONE...TODAY AND TONIGHT Showers and thunderstorms will develop late this morning and track east through the afternoon and evening hours. A few of these storms will be strong to marginally severe and contain strong gusty winds and possibly large hail. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY Expect daily chances for afternoon and evening thunderstorms for the upcoming work week...mainly east of Interstate 25. Thunderstorm coverage should become more isolated by Tuesday and Wednesday. .Spotter information statement... Spotter activation will not be needed.
Special Weather Statement
National Weather Service Cheyenne WY
208 PM MDT Sun Jun 30 2024
WYZ106-107-117-118-302100-
East Platte County WY-
Central Laramie Range and Southwest Platte County WY-
Central Laramie County WY-South Laramie Range Foothills WY-
208 PM MDT Sun Jun 30 2024
...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN GOSHEN...
NORTHWESTERN LARAMIE AND SOUTHERN PLATTE COUNTIES THROUGH 300 PM
MDT...
At 207 PM MDT, Doppler radar was tracking a strong thunderstorm 13
miles east of Sybille Canyon, or 25 miles south of Wheatland, moving
northeast at 35 mph.
HAZARD...Wind gusts up to 50 mph and penny size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
Locations impacted include...
Chugwater and Slater.
This includes Interstate 25 in Wyoming between mile markers 42 and
70.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4155 10516 4169 10527 4202 10481 4178 10465
4159 10465
TIME...MOT...LOC 2007Z 233DEG 31KT 4170 10513
MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH
NatoliThe Cheyenne radar (KCYS), 56 km away, was scanning. The volume nearest the first event began at 20:36 UTC.
6 thunderstorm wind, 2 hail. Local standard time, as filed.
A wind gust to 68 MPH was recorded at the Bear Creek WYDOT sensor 8 miles S of Chugwater.
A wind gust to 65 MPH was recorded at the Bear Creek WYDOT sensor 8 miles S of Chugwater.
Guernsey State Park officials reported quarter sized hail 2 miles NNW of Guernsey.
The public reported ping pong ball sized hail in Hartville.
An NWS Employee estimated wind gusts near 70 MPH 5 miles NNW of Cheyenne.
The public reported an estimated wind gust to 65 MPH 6 miles NNW of Cheyenne.
A trained weather spotter reported pole barns destroyed northeast of the intersection of Iron Mountain Road and Powderhouse Road in North Cheyenne. Wind gusts were estimated at 80 MPH.
An NWS Employee measured a wind gust to 66 MPH with a handheld Kestrel weather instrument 3 miles E of Cheyenne.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2024Every state in 2024This day in weather historyWarnings in Wyoming, June 2024
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1182504, 1182505, 1182506, 1182507, 1182508, 1182509, 1182510, 1182511.