A combination of rain and snow melt produced minor flooding around Medicine Lodge Creek as the creek rose to flood stage. Flooding remained in low lying areas and caused no damage.
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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 combination of rain and snow melt produced minor flooding around Medicine Lodge Creek as the creek rose to flood stage. Flooding remained in low lying areas 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 May 26, 10:11 PM MST, 1 hour 49 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1111 PM MDT Sat May 26 2018 .SHORT TERM...This evening through Tuesday Issued at 141 PM MDT Sat May 26 2018 A weak high pressure ridge with southwest flow aloft over the area will limit moisture and instability supporting isolated to widely scattered showers and thunderstorms mainly over the mountains this evening. As a Pacific low pressure trough over the western Great Basin shifts slowly east, moisture and instability will increase in the southwest flow bringing a significant increase in showers and thunderstorms on Sunday. Temperatures will begin to cool tonight and more on Sunday. The warm temperatures and breezy conditions tonight will accelerate snow melt runoff with most rivers and streams expected to rise to near bankfull with some flooding. Please check on local flood products in your area. Sunday and Monday significant rainfall of 1 to 2 inches will be possible adding to flooding concerns. Showers and isolated thunderstorms will decrease in overall coverage on Tuesday with warming temperatures. .LONG TERM...Tuesday night through Saturday Issued at 141 PM MDT Sat May 26 2018 A few lingering showers from the exiting system Tuesday night followed by a weak ridge Wednesday. Wednesday should be warm and dry for the most part, then we repeat the setup from the previous system Thursday. Split trough/upper low riding over the Great Plains ridge Thursday bringing more showers and storms to the west and north. Most activity will be in the afternoon and evening of Thursday and Friday followed by another weak ridge on Saturday. One area that looks to be mostly spared from this system is Southeast Sweetwater County. This area looks to get strong winds, low RH and little if any precip on Thursday/Friday which could lead to fire weather concerns down the road. && .AVIATION...For the 06Z TAFS through 06Z Monday Issued at 1045 PM MDT Sat May 26 2018 West of the Continental Divide...KJAC/KBPI/KPNA/KRKS Isolated showers will occur overnight into Sunday morning. Scattered showers and thunderstorms will develop over the west around 18Z and continue through 06Z Monday. Wind gusts to 35 knots and small hail will be likely with stronger storms. Mountains will be obscured at times. Expect VFR conditions at the terminal sites, but MVFR conditions will occur in thunderstorms. East of the Continental Divide...KCPR/KCOD/KRIW/KLND/KWRL Isolated showers will occur overnight into Sunday morning. Scattered showers and thunderstorms will develop over the region around 18Z and continue through 06Z Monday. Wind gusts to 35 knots and hail will be likely with stronger storms. Mountains will be obscured at times. Expect VFR conditions at the terminal sites, but MVFR conditions will occur in thunderstorms. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Issued AT 141 PM MDT Sat May 26 2018 A weak high pressure ridge with southwest flow aloft over the area will limit moisture and instability supporting isolated to widely scattered showers and thunderstorms mainly over the mountains this evening. As a Pacific low pressure trough over the western Great Basin shifts slowly east, moisture and instability will increase in the southwest flow bringing a significant increase in showers and thunderstorms on Sunday. Temperatures will begin to cool tonight and more on Sunday. The warm temperatures and breezy conditions tonight will accelerate snow melt runoff with most rivers and streams expected to rise to near bankfull with some flooding. Please check on local flood products in your area. Sunday and Monday significant rainfall of 1 to 2 inches will be possible adding to flooding concerns. Showers and isolated thunderstorms will decrease in overall coverage on Tuesday with warming temperatures. Mixing heights in the afternoons should be high enough for good smoke dispersal except in areas with heavier precipitation. && .RIW WATCHES/WARNINGS/ADVISORIES... Flood Watch from Sunday morning through Monday afternoon for WYZ002>004-006-008-009-012-015>017. && SHORT TERM...Baker LONG TERM...Hulme AVIATION...AR FIRE WEATHER...Baker
Hazardous Weather Outlook National Weather Service Riverton WY 307 AM MDT Sat May 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- 307 AM MDT Sat May 26 2018 This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight Isolated to scattered afternoon and evening thunderstorms mainly in western Wyoming. Isolated storms may be strong to severe across Grand Teton and Yellowstone National Park. .DAYS TWO THROUGH SEVEN...Sunday through Friday Sunday and Monday...Scattered showers and thunderstorms developing over most of the area. Locally heavy rain may elevate the flood threat along rivers and creeks already running high from snowmelt. Isolated strong to severe thunderstorms are possible on Sunday in central Wyoming, especially Johnson County. Tuesday...Isolated to scattered showers and thunderstorms across the area. Wednesday through Friday...Isolated to scattered showers and thunderstorms mainly in the north and west. .SPOTTER INFORMATION STATEMENT... Spotters are urged to report hail, wind gusts past 45 mph and any flooding. Thank you.
Special Weather Statement National Weather Service Riverton WY 1133 PM MDT Sat May 26 2018 WYZ009>011-270730- Bighorn Mountains Southeast-Northeast Johnson County- Southeast Johnson County- Including the cities of Buffalo and Kaycee 1133 PM MDT Sat May 26 2018 Thunderstorms will move from south to north across Johnson county through 130 AM. Some storms will have brief heavy rain, small hail and wind gusts around 30 mph. Frequent lightning will also occur with the stronger storms. Take safe shelter indoors when storms approach your location. AR
The national radar mosaic for the moment the first event began.
1 flood. Local standard time, as filed.
The Medicine Lodge Creek rose to flood stage briefly on the morning of May 27th.
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, May 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: 749614.