A strong cold front moved across Wyoming on August 26th. Strong cold advection and strong mid level winds mixing to the surface brought high winds to some locations.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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 strong cold front moved across Wyoming on August 26th. Strong cold advection and strong mid level winds mixing to the surface brought high winds to some locations. The strongest wind gust was recorded at Red Canyon where a wind gust to 74 mph was recorded. In Natrona County, a 60 mph wind was recorded at the Natrona County airport.
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 Aug 26, 11:10 AM MST, 1 hour 25 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1210 PM MDT Sun Aug 26 2018 .SHORT TERM...Today and Tuesday night Warm, dry and breezy conditions will continue across much of the forecast area today. The approaching trough, currently over ID, will move over the area between 15Z and 21Z, increasing winds with gusts of 30 to 40 mph across much of the forecast area. Temperatures will also stay warm (except northwest portions), with little to no precipitation. Another shortwave will follow behind this one, bringing the bulk of colder temperatures and precipitation with it. Showers will begin to increase over northwest portions Sunday night, as snow levels drop to 9000 to 10k feet by 12Z Monday. This trend will spread across western portions through the morning hours, as the associated cold front makes its way east of the Divide. West to southwest winds ahead of the cold front will be strong again, with gusts of 30 to 45 mph. The strongest gusts will be over wind prone locations, like the Wind Corridor. Isolated to scattered showers will occur over northern and central portions Monday afternoon. Snow levels over the western mountains will generally stay between 9000 and 10k feet, with portions of Yellowstone and northern Absaroka Mountains dropping to 8500 feet. Snow levels in the Bighorns will range between 10k and 11k feet. With all that said, confidence is low for high snowfall amounts during the day Monday. As snow levels continue to drop Monday night, precipitation will end from west to east. A few showers may linger over the northern mountains Tuesday, otherwise conditions will be dry and unseasonably cool (although doubt anyone is going to complain about highs in the 60s for late August). .LONG TERM...Wednesday through Sunday Dry Wednesday and warmer high temps but still pleasant for late summer. Dry on Thursday for most places. Isolated showers or storms over the northwest and north mountains may occur in the afternoon and evening. Warm high temps on Thurs. The next weather system that may impact the north half of the region is slated for Friday into Fri night. The GFS is now weaker with most of the energy moving through Montana. The ECMWF is stronger with the potential for more weather over northern WY as it passes by. Will add low chance of showers and storms over the far north with dry weather elsewhere on Fri into Fri evening. A little cooler highs on Fri. Will see how the models handle this weather system in the upcoming days and make adjustments as needed. Saturday looks to be dry with mild high temps. Next Sunday, the GFS model has another weather system moving through the area with some showers and storms developing. The ECMWF model is dry. Will keep the low chance of showers and storms in the forecast per the GFS, but confidence is low. && .AVIATION...For the 18Z TAFS through 18Z Monday The main aviation concern will be windy southwest to west wind continuing to develop early this afternoon across much of the area and will continue until around sunset. After 00Z Monday, an approaching storm system will increase cloudiness from west to east with widespread showers developing after 06Z Monday across the far west/northwest with mountain obscurations. MVFR ceilings with rainfall could impact KJAC after about 09Z Monday, but will only hint at this for now in the JAC TAF. && .FIRE WEATHER... Red Flag conditions will continue across central and southern zones today, as RH values remain in the lower teens. Have added Zone 288 to the Red Flag Warnings. In addition, west to southwest winds with gusts of 30 to 40 mph will occur over much of the area. Conditions will remain dry for much of the day, with increasing chances over northwest portions late Sunday night into Monday. These showers will spread south and east through Monday morning, staying confined over all but southern portions. && .RIW WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 9 PM MDT this evening for WYZ277>279-288- 289. Red Flag Warning from noon today to 9 PM MDT this evening for WYZ280-281-283-300-414. && SHORT TERM...LaVoie LONG TERM...AR AVIATION...Murrell/Lipson FIRE WEATHER...LaVoie
Hazardous Weather Outlook National Weather Service Riverton WY 245 AM MDT Sun Aug 26 2018 WYZ001>020-022>030-271100- Yellowstone National Park-Absaroka Mountains-Cody Foothills- North Big Horn Basin-Southwest Big Horn Basin- Southeast Big Horn 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- 245 AM MDT Sun Aug 26 2018 ...Red Flag Warning for today for much of southern...central and eastern Wyoming... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Critical fire weather conditions will occur in central and south today and this evening. Very low relative humidity and gusty winds with warm temperatures will create this hazard. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Monday...Scattered showers with isolated thunderstorms over north and central portions. Snow in the highest elevations of the northern and western mountains. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed.
The national radar mosaic for the moment the first event began.
2 high wind. Local standard time, as filed.
Several wind gusts over 58 mph were recorded at Red Canyon, including a maximum wind gust of 74 mph.
The Natrona County airport reported a wind gust to 60 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2018Every state in 2018This day in weather historyWarnings in Wyoming, August 2018
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: 780411, 780412.