A strong area of low pressure passed to the north of the area and whipped a cold front across Wyoming. The tight pressure gradient as it passed through brought high winds to portions of Sweetwater County with a wind gust of 59 mph reported at the Rock Springs airport.
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The episode as NWS RIW wrote it up.
A strong area of low pressure passed to the north of the area and whipped a cold front across Wyoming. The tight pressure gradient as it passed through brought high winds to portions of Sweetwater County with a wind gust of 59 mph reported at the Rock Springs airport. In Lincoln County, a strong thunderstorm brought a 65 mph wind gust to the Fossil Butte National Monument.
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 Sep 29, 3:12 AM MST, 6 hours 13 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 412 AM MDT Sun Sep 29 2019 .SHORT TERM...Today through Tuesday night We are finally seeing a downward trend in showers East of the Divide at this time as the best energy shifts further west. All in all, for areas East of the Divide should have a drier day than yesterday. But notice how I said drier, not dry. All areas will have a chance of showers and thunderstorms once again, but for most areas it should be dry most of the time. In addition, we will have the added threat of high winds today in areas prone to southwest flow ahead of cold front passages. With 700 millibar winds around 50 to 55 knots and decent downward forcing, we hoisted high wind warnings for Natrona County and eastern Sweetwater County. However, this will be borderline and largely confined to the more wind prone areas like Wyoming Boulevard and more eastern portions of Sweetwater County near Wamsutter. There is also the chance of strong wind gusts with any shower to thunderstorm that fires as a cold front moves across the area. Colder air will move in tonight, but moisture should be exiting so most lower elevation areas will only see flurries at most as snow levels drop. Meanwhile, out west rain and high elevation snow continues this morning. The models remain consistent and having the heaviest precipitation this morning then a gradual drying trend from south to north as the deepest moisture moves into Montana. The Winter Weather Advisories and Flood Watches looked fairly good so we continued them as is for now. The afternoon should feature a gradually decreasing coverage of showers. As for snow in the valleys, there was some briefly in the morning yesterday and there could be some starting around late morning as colder air moves in following the cold front. Any accumulation would be minor at best since the deeper moisture will likely be moving away and ground temperatures still warm. Just about all the showers should end by later Sunday night. Things look cool but not as active for Monday and Tuesday. Another system will move up from Utah for Monday. This one is a fast mover and does not have a ton of moisture to work with though. With the colder air in place, much of the precipitation will fall as snow in the west but amounts should remain sub advisory. Meanwhile, East of the Divide showers should be confined to the north. Even here, the lower elevations could see a few snow flurries at times. Tuesday looks to be coolest day of the period. Another wave will be in the area this day but has even less moisture with it so any precipitation is expected to be of the light variety. .LONG TERM...Wednesday through Saturday Some lingering showers are possible Wednesday as the upper low moves out of the area, but most locations will be drying out. With moderate ridging building a warming trend will occur through the end of the work week with temperatures rising to near normal. The next system bringing precipitation will approach the region by next weekend, but models are not yet in agreement with timing and coverage. In particular, the ECMWF is indicating Friday afternoon could see scattered showers across the northern half of the area while the GFS is dry. Have kept precip chances more in line with the ECMWF for now. Gusty afternoon winds will likely return next weekend across southern Wyoming. && .AVIATION...12Z Issuance Rain and mountain snow will occur along and west of the continental divide through the day. MVFR conditions will be widespread through 00Z with areas of IFR conditions. Rain and snow will decrease after 00Z with VFR to MVFR conditions occurring. Mountains will be frequently obscured. Isolated rain and snow showers will occur after 01Z. Along and east of the continental divide, scattered showers and isolated thunderstorms will occur through 00Z. The cold front will move east through this area from 21Z through 01Z. The showers and storms will decrease after 00Z with only isolated activity by 06Z. VFR to MVFR conditions will occur through 00Z with local IFR conditions in areas of heavier precipitation. Mountains will be frequently obscured. && .FIRE WEATHER... A cold front will move across the state today. Rain and mountain snow will continue in the west with the heaviest in the morning. Showers and isolated thunderstorms will be possible East of the Divide as the front moves through. Breezy to windy conditions will be found across much of the area with high winds possible in portions of Sweetwater and Natrona Counties. Relative humidity will remain above critical levels. Mixing and smoke dispersal will be range from poor in the northern basins to excellent in the eastern and southern locations. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 6 PM MDT this evening for WYZ001- 002-012-014. Flash Flood Watch until noon MDT today for WYZ013-023>025. High Wind Warning from noon today to 7 PM MDT this evening for WYZ020. High Wind Warning from 9 AM this morning to 7 PM MDT this evening for WYZ030. && SHORT TERM...Hattings LONG TERM...Myers AVIATION...Ross FIRE WEATHER...Hattings
Hazardous Weather Outlook National Weather Service Riverton WY 401 AM MDT Sun Sep 29 2019 WYZ001>020-022>030-301015- 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- 401 AM MDT Sun Sep 29 2019 ...Winter Weather Advisory for the Northwestern Mountains through today... ...Flash Flood Watch for Lower Elevations across parts of Western Wyoming through this Morning... ...High Wind Warning for Natrona County and Eastern Sweetwater County today... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Today...The coverage and intensity of the precipitation will decrease during Sunday morning. Strong to possibly high wind could occur mainly between Rock Springs and Casper. Sunday night...A first, widespread freeze is likely over the west and south in places that have not hit freezing this season. A light freeze could occur in some locations east of the Divide with the Upper Wind River Basin Foothills, and Cody Foothills the most likely area to see a widespread freeze. .DAYS TWO THROUGH SEVEN...Monday through Saturday. Monday...Snow showers likely over northwestern Wyoming. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures.
The Riverton/Lander radar (KRIW), 160 km away, was scanning. The volume nearest the first event began at 16:24 UTC.
1 high wind, 1 thunderstorm wind. Local standard time, as filed.
A 59 mph wind gust was reported at the Rock Springs airport.
A Park Service employee reported a 65 mph wind gust at the Fossil Butte National Monument.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2019Every state in 2019This day in weather historyWarnings in Wyoming, September 2019
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: 854753, 854754.