Slow moving thunderstorms brought locally heavy rain to portions of Fremont County, Wyoming. The worst flooding was east of DuBois, Wyoming, where mud flows caused by a clogged culvert closed US 20 26 for three hours.
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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.
Slow moving thunderstorms brought locally heavy rain to portions of Fremont County, Wyoming. The worst flooding was east of DuBois, Wyoming, where mud flows caused by a clogged culvert closed US 20 26 for three hours. Some flooding was also noted along Red Canyon Road in the Lander, Wyoming Foothills.
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 22, 1:57 PM MST, 1 hour 3 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 257 PM MDT Mon Jul 22 2019 .SHORT TERM...(This evening through Tuesday) Issued at 221 PM MDT Mon Jul 22 2019 Thunderstorms starting to percolate along the higher elevations this afternoon, being buoyed by midlevel impulse and daytime heating reaching the mid 80s in places. Steering flow is not very strong, so some storms may produce some brief heavy downpours. As the wave shifts east, some showers may continue for Natrona county well into this evening before dissipating. Conditions tomorrow will be similar to today, with daytime heating sparking thunderstorms on the higher elevations, and slowly drifting east during the afternoon. .LONG TERM...(Tuesday night through Monday) Issued at 221 PM MDT Mon Jul 22 2019 By Wednesday the ridge will begin to break down, with a cold front moving across the area. Isolated convection will possible through Thursday but mainly limited to higher elevations and across southern Wyoming. Moisture will return by Friday evening, as models continue to show a shortwave in relatively zonal flow kicking off perhaps more widespread convection coverage Friday night through the weekend. Despite the chances for thunderstorms each day, many locations will remain dry. This means continued drying of fuels, and coupled with lightning and gusty thunderstorm winds, fire weather conditions will need to be closely monitored. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) Issued at 1210 PM MDT Mon Jul 22 2019 Mainly VFR conditions expected today. There will likely be afternoon and evening high- based thunderstorms, mainly along and east of the Divide. Very brief IFR/MVFR conditions are possible in convection. Wind will be relatively light today, but breezy easterly winds are expected to develop this evening mainly across Natrona and Sweetwater counties. && .FIRE WEATHER... Issued AT 221 PM MDT Mon Jul 22 2019 Warm to hot weather continues the next several days. Scattered showers and thunderstorms are expected the rest of today and again tomorrow during peak heating. Thunderstorms are expected to be slow movers, so risk of dry lightning is slightly lessened. Humidity will again fall below 20 percent for all lower elevations due to higher temperatures. Lack of defined weather systems nearby will keep winds low for all areas, except for near thunderstorms. Mixing and smoke dispersion will range from fair to very good. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...Straub LONG TERM...Myers AVIATION...Myers FIRE WEATHER...Straub
Hazardous Weather Outlook National Weather Service Riverton WY 327 AM MDT Mon Jul 22 2019 WYZ001>020-022>030-230930- 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- 327 AM MDT Mon Jul 22 2019 This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight Isolated late day and evening thunderstorms, most numerous East of the Divide. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Tuesday and Wednesday...Isolated to widely scattered thunderstorms in the afternoon and evening. Friday...Isolated late afternoon and evening thunderstorms over the far west. Saturday...Isolated to widely scattered thunderstorms over central and southern portions. .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 235 PM MDT Mon Jul 22 2019 WYZ015-017>019-222115- Wind River Basin-Wind River Mountains East-Green Mountains and Rattlesnake Range-Lander Foothills- 235 PM MDT Mon Jul 22 2019 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN FREMONT COUNTY UNTIL 315 PM MDT... At 233 PM MDT, Doppler radar was tracking an areas of strong thunderstorms near Lander, moving northeast at 25 mph. Pea size hail and winds in excess of 30 mph will be possible with this storm. LAT...LON 4251 10848 4286 10898 4305 10850 4272 10799 TIME...MOT...LOC 2033Z 238DEG 20KT 4276 10860 Myers
Special Weather Statement
National Weather Service Riverton WY
324 PM MDT Mon Jul 22 2019
WYZ019-222200-
Green Mountains and Rattlesnake Range-
324 PM MDT Mon Jul 22 2019
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN FREMONT COUNTY UNTIL
400 PM MDT...
At 324 PM MDT, Doppler radar was tracking a strong thunderstorm 8
miles southeast of Sand Draw, which is 18 miles northwest of Jeffrey
City, moving east at 10 mph.
Half inch hail and winds in excess of 30 mph will be possible with
this storm.
This storm will remain over mainly rural areas of southeastern
Fremont County.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.
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.
&&
LAT...LON 4256 10776 4264 10811 4276 10810 4276 10799
4275 10798 4276 10796 4276 10793 4277 10792
4278 10783 4277 10781 4277 10779 4273 10775
TIME...MOT...LOC 2124Z 278DEG 8KT 4269 10805
MyersSpecial Weather Statement National Weather Service Riverton WY 330 PM MDT Mon Jul 22 2019 WYZ002-003-222215- Cody Foothills-Absaroka Mountains- 330 PM MDT Mon Jul 22 2019 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN PARK COUNTY UNTIL 415 PM MDT... At 330 PM MDT, Doppler radar was tracking a strong thunderstorm 10 miles east of Valley, which is 26 miles west of Meeteetse, moving east at 20 mph. Half inch hail and winds in excess of 40 mph will be possible with this storm. This storm will remain over mainly rural areas of southeastern Park County, including the following locations... Sunshine Reservoir. PRECAUTIONARY/PREPAREDNESS ACTIONS... Brief heavy rainfall is also occurring with this storm. && LAT...LON 4408 10948 4426 10951 4430 10897 4404 10896 TIME...MOT...LOC 2130Z 265DEG 19KT 4418 10940 AR
Special Weather Statement
National Weather Service Riverton WY
347 PM MDT Mon Jul 22 2019
WYZ019-222230-
Green Mountains and Rattlesnake Range-
347 PM MDT Mon Jul 22 2019
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN FREMONT AND
NORTHEASTERN SWEETWATER COUNTIES UNTIL 430 PM MDT...
At 346 PM MDT, Doppler radar was tracking an area of strong
thunderstorms near Jeffrey City, moving east at 25 mph.
Half inch hail and winds in excess of 30 mph will be possible with
this storm.
This strong thunderstorm will be near...
Jeffrey City around 355 PM MDT.
Split Rock around 425 PM MDT.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.
&&
LAT...LON 4243 10752 4223 10752 4218 10767 4215 10788
4232 10795 4241 10802 4253 10802 4259 10789
4259 10755 4243 10751
TIME...MOT...LOC 2146Z 258DEG 20KT 4248 10788
MyersThe Riverton/Lander radar (KRIW), 45 km away, was scanning. The volume nearest the first event began at 22:00 UTC.
2 flash flood. Local standard time, as filed.
Some flooding occurred along Red Canyon Road to the south of Lander, Wyoming.
Heavy rain and a clogged culvert caused rain and mud to flow across US Route 20 26 about 13 miles east of Dubois, Wyoming between mile markers 69 and 70. The Wyoming Department of Transportation had bring out plow trucks to remove the mud.
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, July 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: 839496, 839495.