Very warm temperatures caused rapid snowmelt in the Bighorn Mountains and brought minor flooding around Medicine Lodge State Park. The flooding remained in the low lying areas near the Big Horn River and caused no damage.
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The episode as NWS RIW wrote it up.
Very warm temperatures caused rapid snowmelt in the Bighorn Mountains and brought minor flooding around Medicine Lodge State Park. The flooding remained in the low lying areas near the Big Horn River and caused no damage.
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 Jun 3, 10:09 PM MST, 1 hour 51 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1109 PM MDT Thu Jun 3 2021 .SHORT TERM...This evening through Friday night Strong ridging continues over most of the western CONUS today. This will keep the CWA hot and dry the rest of this afternoon, with many locations nearing or exceeding high temperature records. The ridge will flatten somewhat on Friday, but 700mb temperatures will generally peak Friday afternoon in the 16C to 18C range as this occurs; Friday will be the hottest day of the year thus far with likely widespread broken or near-broken high temperature records. With the flattening ridge and weak instability, isolated convection does look more likely Friday, mainly across the north. A weak cold front will arrive Friday evening which will keep isolated showers and thunderstorm chances across the far northwest through early Saturday morning. .LONG TERM...Saturday through Wednesday A ridge will be in place over the Northern Plains/central Canada Saturday, as a storm system digs over the EPAC. This will result in southwest flow aloft over the Cowboy State. This overall pattern will be in place through the period. Near record highs remain possible Saturday, with temperatures staying above normal through the forecast period. 700mb temperatures of 13C to 16C will also remain in place Saturday, as another cold front clips northern portions of the forecast area. This front will be supported by a relatively strong jet, as the associated trough clips northwestern portions of Yellowstone. This will result in a windier day across much of the forecast area, with gusts up to 35 mph possible. This looks to be a dry front, with any thunderstorm activity over the High Plains/eastern border of WY. Cooler conditions will be possible over far northern portions Sunday, in the wake of the front. Gusty afternoon winds will then become likely over the Wind Corridor. The ridge rebuilds over the Northern/Central Plains Monday, blocking the EPAC storm system from progressing eastward. Dry, hot and windy conditions look likely Sunday through Wednesday, leading to elevated fire conditions for central and southern portions. Record high temperatures will be possible Tuesday, as 700mb temperatures increase to 17C to 19C. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 1107 PM MDT Thu Jun 3 2021 VFR conditions will prevail across all TAF sites through the period. Light and variable winds can be expected at all terminals before picking up across all TAF sites after 18Z. Wind gust could exceed 25 knots at sites KBPI, KCOD, KLND, KPNA, KRIW AND KRKS. Site KWRL could see a few gusts up to 20 knots. Those winds are expected to diminish after 03Z. A few low clouds may sneak into the region after 18Z and sticking around through the period. Have added VCTS at site KCOD for the potential of scattered thunderstorms after 21Z. && .FIRE WEATHER... Issued at 1059 AM MDT Thu Jun 3 2021 Hot and dry conditions across the area today. Winds will generally be light and terrain driven in the mountains. Smoke dispersal will generally be good in most locations, despite the light winds. Near record high temperatures are expected Friday, with a slight chance of a thunderstorm over the northwest and north. Although critical relative humidity values will occur in the lower elevations east of the Divide and the southwest both days, winds will not meet critical fire weather thresholds. Elevated fire weather conditions, due to critical RH values, southwest winds gusts over 25 mph and above normal temperatures, are expected at times this weekend into early next week over central and southern areas. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...Myers LONG TERM...LaVoie AVIATION...Vorst FIRE WEATHER...Murrell/LaVoie
Hazardous Weather Outlook National Weather Service Riverton WY 145 AM MDT Thu Jun 3 2021 WYZ001>020-022>030-041200- 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- 145 AM MDT Thu Jun 3 2021 This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight Unseasonably warm temperatures will result in rapid snowmelt across the high-elevation mountains. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Friday...Unseasonably warm with daytime highs climbing to 15 to 20 degrees above normal. Active snowmelt in the mountains will result in rising water on creeks, streams, and rivers. The North Fork Shoshone River, the upper Wind River around Dubois, and Shell Creek remain the most likely candidates for rising water levels given the snowpack that remains above 9,000 feet. Saturday through Tuesday...Continued warm. Elevated fire weather conditions are possible across southwest Wyoming as a west to southwest wind increases. Mountain snowmelt continues with rising water levels on creeks, streams, and rivers. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions.
The national radar mosaic for the moment the first event began.
1 flood. Local standard time, as filed.
Please see episode for event description.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2021Every state in 2021This day in weather historyWarnings in Wyoming, June 2021
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: 956976.