A deep trough moved into Wyoming and was supportive of numerous showers and thunderstorms. The strongest storms moved through Fremont and Natrona Counties, where wind gusts of over 70 mph were reported.
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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 RIW wrote it up.
A deep trough moved into Wyoming and was supportive of numerous showers and thunderstorms. The strongest storms moved through Fremont and Natrona Counties, where wind gusts of over 70 mph were reported. In Hudson, numerous trees were uprooted or snapped. In Lander, a tree was uprooted and fell on a truck. Maximum measured wind gusts included 72 mph near Lander and 70 mph on the east side of Casper. A spotter estimated a wind gust of 77 mph in Bar Nunn.
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 Riverton, WY wrote its last area forecast discussion before the first event at Jul 15, 12:43 PM MST, 37 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Riverton WY 143 PM MDT Mon Jul 15 2024 .KEY MESSAGES... - Scattered thunderstorms will produce brief heavy rain and gusty outflow wind of 35 to 45 mph through early Monday evening. - A secondary surge of northerly surface wind arrives Tuesday afternoon and evening. This will allow wildfire smoke to increase along the Interstate 25 corridor in Johnson and Natrona Counties. Oregon wildfire smoke will reach western Wyoming tonight and Tuesday. - Temperatures at or just above seasonal averages along with typical diurnal convection prevails much of the period. && .DISCUSSION... Issued at 143 PM MDT Mon Jul 15 2024 Scattered convection is ongoing as of 130 PM Monday across western and central Wyoming. The strongest storms and greatest areal coverage is across southwest Wyoming where a lack of cloud cover earlier today has allowed for better destabilization as mid-level lapse rates are ranging from 8-9C/km. Further destabilization is expected across central Wyoming through mid-afternoon as solar radiation has increased the past few hours. With precipitable water values topping 0.80 inches, these storms will be producing rain Monday afternoon and early evening. Temperature-dew point spreads favor wind gusts 35 to 45 mph with the stronger convection. CAMS show most of the stronger storms relegated to locations over Natrona and eastern Sweetwater Counties by 5-6 PM. Showers and isolated storms eventually develop over northcentral Wyoming late this afternoon. This activity tracks east-southeast through the evening, lingering longest in Natrona County. To the west, drier westerly flow aloft brings an earlier end to the convection this evening. However, western wildfire smoke, mainly from Oregon, is likely to filter into the region in this flow regime. Tuesday finds enough lingering mid-level moisture to trigger convection around midday. Orographics favor the Absaroka and Wind River Mountains for the best coverage Tuesday afternoon. Drier west- northwest flow aloft should limit convection in the basins east of the Continental Divide. Surface high pressure dropping south through the Northern Plains provides a secondary surge of northerly surface wind east of the Divide Tuesday afternoon. Wildfire smoke from southern Montana fires is likely to make a push farther south into central Wyoming along the Interstate 25 corridor in Johnson and Natrona Counties given this wind direction. Temperatures will be around seasonal normals with the exception of cooler readings in Johnson County. The north to northeast wind reaches Sweetwater County and points westward Tuesday evening, but speeds will generally be only 10 to 15 mph. Convection decreases in coverage early Tuesday evening leaving a clearing sky and seasonal temperatures overnight. The remainder of the week finds a building ridge across the Great Basin, which retrogrades closer to the West Coast late in the forecast period. For the most part, temperatures at or just above seasonal averages prevail through next weekend. Enough mid-level moisture remains trapped under the ridge to keep isolated/scattered diurnal convection in the forecast through at least Friday. As the ridge retrogrades, Wyoming may end up in northerly flow aloft with any southerly moisture surge possibly being tempered. Therefore, next weekend may end up a bit drier. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 1145 AM MDT Mon Jul 15 2024 With slightly above normal atmospheric moisture and moderate instability, scattered to widespread showers and thunderstorms are expected this afternoon across the entire forecast area. The primary threats are brief heavy rain and gusty outflow over 40 kts. Some of the storms in central WY (KCPR-KBYG) may become stronger and also produce hail over one inch. For the most part, the convection will end before sunset with lingering showers possible from west-central WY toward east-central WY. VFR conditions are generally expected, though MVFR conditions are likely if showers/thunderstorms move directly over or near TAF sites. Some mid-level clouds will remain overnight and move southward before sunrise. As the storm-producing weather system moves eastward, some northerly flow will move into sites east of the divide and increase Tuesday afternoon. WNW winds will increase west of the divide. Isolated showers and thunderstorms are expected over the southern Absarokas and Wind Rivers and other mountain areas during the afternoon with sites across central and southern WY the most likely to see isolated storms. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on smoke, icing, and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... Air Quality Alert until 1 PM MDT Tuesday for WYZ010-023-024- 027. && DISCUSSION...CNJ AVIATION...McDonald
Hazardous Weather Outlook National Weather Service Riverton WY 256 AM MDT Mon Jul 15 2024 WYZ001>020-022>030-161300- Yellowstone National Park-Absaroka Mountains-Cody Foothills- North Bighorn Basin-Southwest Bighorn Basin-Southeast Bighorn Basin- Owl Creek and Bridger Mountains-Bighorn Mountains West- Bighorn Mountains Southeast-Northeast Johnson County- Southeast Johnson County-Teton and Gros Ventre Mountains- Jackson Hole-Wind River Mountains West-Wind River Mountains East- Upper Wind River Basin-Wind River Basin-Lander Foothills- Green Mountains and Rattlesnake Range- Natrona County Lower Elevations-Casper Mountain-Star Valley- Salt River and Wyoming Ranges-Upper Green River Basin Foothills- Upper Green River Basin-South Lincoln County- Rock Springs and Green River-Flaming Gorge-East Sweetwater County- 256 AM MDT Mon Jul 15 2024 This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and tonight. Widespread showers and thunderstorms this afternoon and evening. Brief heavy downpours and strong outflows of 40+ mph are the main concerns with the stronger storms that develop. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. Tuesday and Wednesday...Scattered showers and thunderstorms continue through the first half of the week. Strong storms will bring a continued gusty outflow wind threat. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to Standard Operating Procedures.
Special Weather Statement
National Weather Service Riverton WY
150 PM MDT Mon Jul 15 2024
WYZ002-005-007-014>019-026-152015-
Wind River Mountains West-Owl Creek and Bridger Mountains-Wind River
Basin-Upper Green River Basin-Southwest Bighorn Basin-Upper Wind
River Basin-Wind River Mountains East-Green Mountains and Rattlesnake
Range-Absaroka Mountains-Lander Foothills-
150 PM MDT Mon Jul 15 2024
...STRONG THUNDERSTORMS WILL IMPACT WESTERN HOT SPRINGS...
SOUTHEASTERN SUBLETTE...CENTRAL FREMONT AND SOUTHEASTERN PARK
COUNTIES THROUGH 215 PM MDT...
At 149 PM MDT, Doppler radar was tracking strong thunderstorms along
a line extending from 16 miles south of Meeteetse to 6 miles north of
Fort Washakie to 11 miles northeast of Big Sandy Recreational Area.
Movement was east at 30 mph.
HAZARD...Wind gusts up to 40 mph.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects.
Strong thunderstorms will be near...
Fort Washakie, Morton, Anchor Dam, and Pilot Butte Reservoir
around 155 PM MDT.
Ethete, Upper Silas Lake, Worthen Meadows Reservoir, and Christina
Lake around 200 PM MDT.
Frye Lake around 205 PM MDT.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
Persons in campgrounds should consider seeking sturdy shelter until
these storms pass.
&&
LAT...LON 4391 10843 4390 10839 4315 10845 4227 10879
4227 10957 4306 10924 4396 10926 4397 10907
4394 10909 4397 10904 4397 10899 4395 10897
4396 10893 4393 10893 4397 10891 4399 10843
TIME...MOT...LOC 1949Z 261DEG 24KT 4392 10892 4310 10892 4233 10923
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH
McDonaldSpecial Weather Statement
National Weather Service Riverton WY
214 PM MDT Mon Jul 15 2024
WYZ017-018-152045-
Wind River Basin-Lander Foothills-
214 PM MDT Mon Jul 15 2024
...A STRONG THUNDERSTORM WILL IMPACT CENTRAL FREMONT COUNTY THROUGH
245 PM MDT...
At 213 PM MDT, Doppler radar was tracking a strong thunderstorm near
Fort Washakie, moving east at 25 mph.
HAZARD...Wind gusts up to 50 mph and half inch hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor hail damage to vegetation is
possible.
This strong thunderstorm will be near...
Ethete around 220 PM MDT.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
&&
LAT...LON 4313 10859 4285 10851 4282 10886 4286 10889
4287 10891 4288 10892 4305 10896
TIME...MOT...LOC 2013Z 260DEG 21KT 4296 10885
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH
McDonaldThe Riverton/Lander radar (KRIW), 29 km away, was scanning. The volume nearest the first event began at 20:18 UTC.
3 thunderstorm wind. Local standard time, as filed.
Maximum wind gusts of 72 mph were reported to the northwest of Lander.
A severe thunderstorm moved from Lander to Hudson and brought high winds, including a maximum wind gust of 67 mph at the Lander airport. The wind blow a tree on a truck at the Lander courthouse. In Hudson, numerous trees were uprooted or snapped.
A line of severe thunderstorms moved across Natrona County and brought high wind gusts to many locations. The public estimated a 77 mph wind gust in Bar Nunn. Wind gusts from Hiland to Near Bar Nun and Evansville generally ranged from 60 to 70 mph.
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, July 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: 1200577, 1200578, 1200886.