Heavy rain brought flooding in portions of Johnson County north of Buffalo. Highway 193 near Fort Phil Kearney was closed due to flooding from Rock Creek.
Every event with a place to put it. 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.
Heavy rain brought flooding in portions of Johnson County north of Buffalo. Highway 193 near Fort Phil Kearney was closed due to flooding from Rock Creek. Water was also crossing Old Highway 87. No structural damage was reported.
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 28, 1:51 AM MST, 6 hours 9 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 251 AM MDT Mon May 28 2018 .SHORT TERM...(Today through Wednesday night) The band of thunderstorms that moved north across Wyoming east of the divide has become more stratiform in nature and is now relegated to our northeast zones as a 700mb circulation tries to become established over North Central Wyoming. During the heyday of this area of convection, it produced a strong destructive northbound outflow boundary that seemed to gain momentum as it plowed north across the Big Horn Basin with 78 mph winds recorded at the Greybull airport. Most of the lightning has moved northeast of our CWA. Another area of convection is seen creeping north across Sweetwater County probably tied in with another developing 700mb circulation close to the Colorado border. The models want to retrograde the 700mb low over our north central zones northwest into Montana today. Because the jet stream is north of this low, it will take its time exiting back to the east which will likely occur Tuesday. So in the meantime, widespread showers will continue this morning, with another round of convection expected this afternoon and evening with more widespread convective activity expected across the northern two thirds of Wyoming, closer to the mid level low. The strongest thunderstorms this afternoon and evening should take place in Johnson County where lifted indices are progged to be around -5. Southeast Natrona County is in a slight risk today with Casper just barely inside the area. By Tuesday, a dirty northwest flow will become established behind the exiting low/trough which will initiate additional convection Tuesday, but not quite as widespread as today. Then on Wednesday, much drier air will work into the area as a ridge builds in from the west. On Wednesday night, a southwest flow will ensue on the backside of the ridge, drawing in more moisture resulting in a slight chance of thunderstorms in the far west Wednesday night. A warm up will begin Wednesday with high temps recovering back up into the 70s with some 80s in the Big Horn Basin. As for any flooding concerns, we decided to drop the flash flood watch from Natrona County as most of the heavy rainfall has already occurred there earlier this evening. However, Johnson County is seeing the bands of rainfall slowing its forward progression and is spreading back toward the west in response to the circulation around the aforementioned mid level low. Around three tenths of an inch of rainfall has been occurring there, but rainfall rates are tapering off; thus, the Flash Flood threat has been significantly reduced early this morning. The flood watch has been reduced to just cover an area from the Big Horn Mtns west to the Absarokas. Rain on snow at the higher elevations is no longer as much of a concern since snow falling on snow has been occurring over 9K including Togwotee Pass, and the snow level will likely lower briefly to elevations of around 7K or so as h7 temps drop to around 3.5C this morning. With that said, less high elevation snow melt would occur, even where precip is expected to fall. .LONG TERM...(Thursday through Monday) A Pacific cold front will move east across the area Thursday night. A warm, dry southwest flow will prevail across south and central Wyoming ahead of the front on Thursday, with chances of afternoon evening thunderstorms across the northwest and far north. The better instability, potential for strong/severe thunderstorms will be mainly across SE Montana and the High Plains on Thursday, but higher CAPES could wrap back into northern Johnson county and the northern Big Horn Basin. A cooler, more stable airmass will prevail behind the cold front on Friday, except possibly along and east of the Bighorn mountains, where slight chances of thunderstorms will linger through Friday evening. A dry southwest flow will then reestablish over the area next weekend. Deterministic models show a sub-tropical low lifting from southern California into the area, but substantial differences in track and timing lead us to discount any effects of this system for this forecast package. && .AVIATION...(For the 12Z TAFS through 12Z Tuesday morning) |est of the Continental Divide...KJAC/KBPI/KPNA/KRKS Expect lingering showers through 18Z. Then scattered showers and thunderstorms will develop over the area after 18Z. The activity will decrease after 03Z to isolated showers. VFR conditions will prevail through the period. Local MVFR to IFR conditions will occur in thunderstorms. Mountains will be obscured at times. East of the Continental Divide...KCPR/KCOD/KRIW/KLND/KWRL Expect lingering showers through 18Z. Scattered showers and thunderstorms will develop over the region after 18Z. The activity will decrease after 06Z Tue. VFR conditions will prevail through the period. MVFR to IFR conditions will occur in thunderstorms. Mountains will be obscured at times. 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 203 AM MDT Mon May 28 2018 As for any flooding concerns, we decided to drop the flash flood watch from Natrona County as most of the heavy rainfall has already occurred there earlier this evening. However, Johnson County is seeing the bands of rainfall slowing its forward progression and is spreading back toward the west in response to the circulation around the aforementioned mid level low. Around three tenths of an inch of rainfall has been occurring there. The flash flood watch expires at 12Z this morning. However, The flood watch has been reduced to just cover an area from the Big Horn Mtns west to the Absarokas. Rain on snow at the higher elevations is no longer as much of a concern since snow falling on snow has been occurring over 9K including Togwotee Pass, and the snow level will likely lower briefly to elevations of around 7K or so as h7 temps drop to around 3.5C this morning. With that said, less high elevation snow melt would occur, even where precip is expected to fall. && .RIW WATCHES/WARNINGS/ADVISORIES... Flood Watch through this afternoon for WYZ002>004-006-008-009. && SHORT TERM...Lipson LONG TERM...Meunier AVIATION...Ross FIRE WEATHER...Lipson
Hazardous Weather Outlook National Weather Service Riverton WY 309 AM MDT Mon May 28 2018 WYZ001>020-022>030-291100- 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- 309 AM MDT Mon May 28 2018 ...Flood Watch in effect through 6 PM MDT this evening for portions of Northern Wyoming east of the Continental Divide... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Scattered showers and thunderstorms developing over most of the area. Isolated severe thunderstorms possible in east central areas. Locally heavy rain may elevate the flood threat along rivers and creeks already running high from snowmelt. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. Tuesday...Isolated to scattered showers and thunderstorms across the area. Thursday...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. TEAM RIVERTON
The national radar mosaic for the moment the first event began.
1 flood. Local standard time, as filed.
Emergency management reported flooding near Fort Phil Kearney that covered old Highway 87 and temporarily closed Highway 193.
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: 749621.