A persistent, moist, north-northwest flow aloft brought heavy snow to the northern Bighorn Mountains, especially above about 8500 feet. Two day snowfall amounts ranged from 2 to 3 feet in the vicinity of Bald Mountain near US Highway 14A.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. 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.
A persistent, moist, north-northwest flow aloft brought heavy snow to the northern Bighorn Mountains, especially above about 8500 feet. Two day snowfall amounts ranged from 2 to 3 feet in the vicinity of Bald Mountain near US Highway 14A. The snow toppled trees and caused damage to trailers located at a lodge.
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 29, 10:36 PM MST, 2 hours 24 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 1136 PM MDT WED MAY 29 2013 .UPDATE... ADDED 06Z TAF DISCUSSION... && .PREV DISCUSSION... /ISSUED 241 PM MDT WED MAY 29 2013/ SHORT TERM...TONIGHT AND THURSDAY UPPER LOW IS GRADUALLY LIFTING NWD AND APPEARS TO BE JUMPING OVER THE OWL CREEKS AND REDEVELOPING OVER THE WRN HOT SPRINGS COUNTY. VERY COOL AND UNSETTLED AROUND THIS LOW WITH THUNDERSTORMS EAST OF IT AND WIDESPREAD SHOWERS ALL AROUND IT. SNOW CONTINUES IN THE NW MOUNTAINS WITH BEARTOOTH PASS RECEIVING HEAVY SNOW. PLENTY OF SNOTELS INDICATING 4-8 INCHES OF SNOW OR MORE AS OF THIS MORNING. IT WAS CLOSED EARLY TODAY AND REMAINS SO. THE ADVISORY WAS EXTENDED UNTIL 6 PM FOR THE ABSAROKAS BUT ALLOWED TO EXPIRE FOR THE TETONS AND YNP. THE UPPER LOW SHOULD CONTINUE TO SLOWLY LIFT NEWD INTO THURSDAY WITH A SIGNIFICANT SHORTWAVE ROTATING AROUND THE LOW AND COMING DOWN FROM THE NORTH JUST BEYOND THIS PERIOD. THE SMALL STREAM FLOOD ADVISORY WAS ALLOWED TO EXPIRE AT 3 PM AS THE RAIN HAS DECREASED AND THERE HAS BEEN PLENTY OF ELAPSED TIME FOR THE FLOOD WATERS TO DRAIN INTO THE BIGGER STEM RIVERS. SOME HIGH WATER AND MUDDY OR WATER FILLED ROADS WILL LIKELY CONTINUE INTO THE EVENING BUT THE HIGHER THREAT HAS ENDED. LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY THE AREA OF LOW PRESSURE WILL CONTINUES TO MOVE NORTHEAST ON THURSDAY EVENING...WITH CONTINUED SHOWER ACTIVITY EXPECTED ACROSS THE NORTH AND EAST. AS THE SYSTEM CONTINUES...EXPECT WRAP AROUND MOISTURE TO IMPACT THE NORTHEAST...WITH POTENTIALLY SIGNIFICANT SNOWFALL ACTIVITY ACROSS THE BIGHORN MOUNTAINS LATE THURSDAY AND CONTINUING THROUGH FRIDAY EVENING. SHOWER ACTIVITY WILL TAPER OFF BY SATURDAY MORNING AS THE SYSTEM MOVES FURTHER INTO THE MIDWEST. AS THE LOW PRESSURE SYSTEM LOSES ITS INFLUENCE OVER THE AREA...A BUILDING AREA OF HIGH PRESSURE WILL BEGIN TO MOVE INTO THE STATE. GENERALLY DRY CONDITIONS ANTICIPATED WITH THIS RIDGE OF HIGH PRESSURE SATURDAY NIGHT AND INTO SUNDAY. ANOTHER APPROACHING AREA OF LOW PRESSURE WILL MOVE ACROSS NORTHWESTERN MONTANA BY SUNDAY EVENING...WITH SOME SHOWER ACTIVITY POSSIBLE TO REACH INTO NORTHWESTERN WYOMING. ASSOCIATED SHOWERS WILL SPREAD ACROSS NORTHERN WYOMING THROUGH SUNDAY NIGHT. MODELS VARY A FAIR AMOUNT WITH THIS SYSTEM BY TUESDAY MORNING. THOUGH THEY APPEAR TO AGREE THAT CORE OF THE LOW PRESSURE WILL STAY NORTH OF WYOMING...THE DEPTH THAT THE ASSOCIATED TROUGH DIGS REMAINS UP FOR DEBATE. HOW MUCH THIS SYSTEM DIGS WILL ALTER TEMPERATURES AND ASSOCIATED SHOWER ACTIVITY. THE GOING FORECAST KEEPS MOST OF THE PRECIPITATION CONFINED TO THE NORTH...WITH SHOWERS SPREADING ACROSS THE EAST ON WEDNESDAY AS THE SYSTEM CONTINUES ON ITS EASTWARD PROGRESSION. AVIATION.../06Z ISSUANCE/ THE MOUNTAIN SNOW/VALLEY RAIN SHOWERS THROUGH THE PERIOD WILL BE CONCENTRATED ACROSS THE BIGHORN MOUNTAINS AND NORTHEAST BIG HORN BASIN AND NORTHERN JOHNSON COUNTY. ISOLATED SHOWER ACTIVITY COULD BE FOUND AS FAR SOUTH AS ROUGHLY FROM KJAC THROUGH KLND TO KCPR. VERY ISOLATED THUNDERSTORMS WILL REMAIN POSSIBLE IN THOSE AREAS MENTIONED ABOVE. COULD SEE SOME MVFR CEILINGS ACROSS THE FAR WESTERN VALLEYS...INCLUDING KJAC...THURSDAY MORNING BEFORE LIFTING BY MID TO LATE MORNING...THEN THE BULK OF THE MVFR/IFR CONDITIONS WILL BE CONCENTRATED WITH THE PRECIP ACROSS THE BIGHORN MTS AND SURROUNDING LOWER ELEVATIONS. WINDY WEST TO NORTHWEST WINDS WILL DEVELOP BY MIDDAY THURSDAY OVER MUCH OF THE REGION...MORE SOUTH TO SOUTHWEST IN JACKSON HOLE. PLEASE SEE THE AVIATION WEATHER CENTER FOR THE LATEST INFORMATION ON ICING AND TURBULENCE FORECASTS. FIRE WEATHER... IT WILL CONTINUE COOL AND UNSETTLED THE NEXT COUPLE DAYS ALONG WITH AREAS OF STRONG WEST TO NORTHWEST WIND. THE NORTHERN MOUNTAINS WILL CONTINUE WITH PERIODS OF SNOW ABOVE 8000 TO 9000 FEET...ESPECIALLY THROUGH THIS EVENING AND AGAIN THURSDAY NIGHT AND FRIDAY. IT WILL BE DRIER IN THE SOUTH WITH GUSTY WEST WINDS. ISOLATED THUNDERSTORMS WILL CONTINUE THIS EVENING AND RETURN EAST OF THE DIVIDE ON THURSDAY. && .RIW WATCHES/WARNINGS/ADVISORIES...NONE. && SHORT TERM...SKRBAC LONG TERM...BRANHAM AVIATION...WM FIRE WEATHER...SKRBAC
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 601 PM MDT WED MAY 29 2013 WYZ001>020-022>030-301200- ABSAROKA MOUNTAINS-BIGHORN MOUNTAINS SOUTHEAST- BIGHORN MOUNTAINS WEST-CASPER MOUNTAIN-CODY FOOTHILLS- EAST SWEETWATER COUNTY-FLAMING GORGE- GREEN MOUNTAINS AND RATTLESNAKE RANGE-JACKSON HOLE-LANDER FOOTHILLS- NATRONA COUNTY LOWER ELEVATIONS-NORTH BIG HORN BASIN- NORTHEAST JOHNSON COUNTY-OWL CREEK AND BRIDGER MOUNTAINS- ROCK SPRINGS AND GREEN RIVER-SALT RIVER AND WYOMING RANGES- SOUTH LINCOLN COUNTY-SOUTHEAST BIG HORN BASIN- SOUTHEAST JOHNSON COUNTY-SOUTHWEST BIG HORN BASIN-STAR VALLEY- TETON AND GROS VENTRE MOUNTAINS-UPPER GREEN RIVER BASIN- UPPER GREEN RIVER BASIN FOOTHILLS-UPPER WIND RIVER BASIN- WIND RIVER BASIN-WIND RIVER MOUNTAINS EAST-WIND RIVER MOUNTAINS WEST- YELLOWSTONE NATIONAL PARK- 601 PM MDT WED MAY 29 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT ISOLATED THUNDERSTORMS WILL REMAIN POSSIBLE THROUGH ABOUT 10 PM. HEAVY RAIN WILL BE THE MAIN HAZARD. THIS COULD CAUSE LOCALIZED FLASH FLOODING AND DEBRIS FLOWS...ESPECIALLY ON ANY BURN SCARS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THURSDAY AND FRIDAY...SEVERAL INCHES OF ADDITIONAL SNOW IN THE NORTHERN MOUNTAINS ABOVE 8000 FEET WITH THE MORE SIGNIFICANT AMOUNTS SHIFTING EAST INTO THE NORTHERN BIGHORN RANGE. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ENCOURAGED TO REPORT RAINFALL AMOUNTS. TEAM RIVERTON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 140 AM MDT THU MAY 30 2013 WYZ010-302200- NORTHEAST JOHNSON COUNTY- 140 AM MDT THU MAY 30 2013 A STRONG LATE SEASON WINTER STORM WILL INCREASE WIND SPEEDS TODAY OUT OF THE NORTHWEST BY MID DAY OVER NORTHERN JOHNSON COUNTY. WIND SPEEDS CAN BE EXPECTED TO BLOW STEADY AT 25 TO 35 MPH WITH GUSTS TO AROUND 45 MPH INTO THIS EVENING. BRAUN
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 145 AM MDT THU MAY 30 2013 WYZ019-028>030-302200- EAST SWEETWATER COUNTY-FLAMING GORGE- GREEN MOUNTAINS AND RATTLESNAKE RANGE-ROCK SPRINGS AND GREEN RIVER- 145 AM MDT THU MAY 30 2013 A STRONG LATE SEASON WINTER STORM WILL INCREASE WIND SPEEDS TODAY OUT OF THE WEST BY MID MORNING OVER MUCH OF SWEETWATER COUNTY. WIND SPEEDS CAN BE EXPECTED TO BLOW STEADY AT 30 TO 35 MPH WITH GUSTS BETWEEN 45 AND 50 MPH INTO THIS EVENING. BRAUN
The national radar mosaic for the moment the first event began.
1 heavy snow. Local standard time, as filed.
A trained spotter reported 36 inches of snow at the High Country Lodge in the Big Horn Mountains. The Bald Mountain SNOTEL at 9380 feet elevation had an estimated 26 inches of snow.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2013Every state in 2013This day in weather historyWarnings in Wyoming, May 2013
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: 446141.