An area of low pressure moving into Wyoming from the southwest combined with a moist atmosphere to produce strong afternoon thunderstorms across northern Wyoming.
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.
An area of low pressure moving into Wyoming from the southwest combined with a moist atmosphere to produce strong afternoon thunderstorms across northern Wyoming.
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 11, 1:33 PM MST, 1 hour 5 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 233 PM MDT TUE JUN 11 2013 .SHORT TERM...TONIGHT AND WEDNESDAY UPPER CIRCULATION IS WEAKENING BUT PASSING ACROSS OUR SERN ZONES WITH A NWRN EXTENSION OF THE TROUGH AT BOTH THE SURFACE AND ALOFT. STORMS FIRING ACROSS THE NW AND N WITH POTENTIAL FOR A FEW STRONG TO SEVERE STORMS. ANY STORM COULD PRODUCE VERY STRONG AND ERRATIC WIND GUSTS OVER 50 MPH. VERY DRY AIR ADVANCING FROM THE SW WITH TEEN AND 20S DEW POINTS COVERING MUCH OF THE SWRN HALF. 50+ DEW POINTS HOLDING IN THE FAR NCNTRL AND NERN ZONES BUT SOME OF THOSE WILL ERODE. STORM POTENTIAL WILL CONTINUE HIGHEST IN NRN JOHNSON AND ALONG THE MONTANA BORDER IN THE NRN BIG HORN BASIN. APPROACHING JET STREAK ON WEDNESDAY WILL BRING THE THREAT OF SOME STRONG THUNDERSTORMS ACROSS THE NW WHERE THE JET SUPPORT MAY COME INTO PLAY ALONG WITH A LITTLE BETTER PW VALUES AND POTENTIALLY AGAIN IN THE NRN BIG HORN BASIN AND JOHNSON COUNTY. THE SOUTH WILL CONTINUE DRY ...VERY WARM AND WINDY. .LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY STUCK BETWEEN A DIRTY RIDGE AND LARGE TROUGH TO THE WEST. LOW PRESSURE RIGHT OVER THE GUT OF CENTRAL WY...WITH EASTERLY TO SOUTHEASTERLY SFC FLOW ACROSS PARTS OF NATRONA AND JOHNSON COUNTIES...MAXIMIZING SHEAR IN THIS AREA BUT WITH MARGINAL MOISTURE TO WORK WIT. STILL POTENTIAL FOR LOW END SEVERE IN THIS AREA EXISTS WEDNESDAY NIGHT...ESPECIALLY FOR SEVERE WINDS. BETTER MOISTURE WILL BE PRESENT OVER NWRN WY...BUT LESS SHEAR. OVERALL...POTENTIAL WILL EXIST ACROSS THE NORTHERN TIER OF COUNTIES FROM WEST TO EAST. THURSDAY... THE SFC LOW AND AND DRY SOUTHWEST FLOW INCHES NORTHWARD AND WILL EFFECTIVE LIMIT CONVECTIVE ACTIVITY TO VERY HIGH BASED STORMS ALONG SPEED CONVERGENCE AND ELEVATED TERRAIN REGIONS OF SWEETWATER AND NATRONA COUNTIES...AND ADDITIONALLY ALONG/NEAR THE WY/MT BORDER...ESPECIALLY IN AND NEAR YELLOWSTONE...THEN EASTWARD TO THE BIG HORNS. NO SEVERE HOWEVER IS EXPECTED IN OUR CWA. FRIDAY...BEST UPPER LEVEL SHORTWAVE TROUGH SWINGS THROUGH NW CORNER OF CWA...BUT WILL HAVE VERY LITTLE TO WORK WITH...SO ONLY SMALL POPS OVER EXTREME NW CWA AT THIS TIME. COLD FRONT ALSO FINALLY MOVES THROUGH...BRINGING DOWN HIGH TEMPS SOME 10 TO 12 DEG. BIGGEST CONCERN FOR THURSDAY AND FRIDAY WILL BE WARM DRY BREEZY TO WINDY CONDITIONS ACROSS SWEETWATER AND PORTIONS OF NATRONA COUNTIES...POSSIBLY RAISING SOME FIRE WX CONCERNS TO NEAR RED FLAG CONDITIONS DEPENDING ON FUEL STATUS. SATURDAY THROUGH TUESDAY...FLAT UPPER FLOW SAT REPLACE BY RIDGING SUN AND MON DEMARKS THE TEMPERATURE TREND...WITH UPPER 80S TO AROUND 90 RETURNING ONCE AGAIN TO THE FORECAST SUNDAY AND MONDAY BEFORE TEMPS BEHIND ANOTHER WEAK COLD FRONT. SLIGHT CHANCES FOR POPS WILL EXIST SUN MON AND TUES AFTERNOONS OVER MAINLY THE THE MOUNTAINS...BUT GENERALLY ROBUST UPPER LEVEL RIDGING WILL PREVAIL OVER THIS PERIOD WITH LITTLE CHANCES FOR PRECIPITATION EXCEPT OVER THE HIGH TERRAIN...UNTIL THE CLOSED TROUGH OVER THE PAC NW REGION FEELS THE NEED MOVE THIS WAY. ATTM...MODELS ARE NOT SHOW IT LIFTING OUT UNTIL MID TO END OF NEXT WEEK. .AVIATION.../00Z ISSUANCE/ SOUTHWEST FLOW AT 15 TO 25KT ACROSS THE SOUTHERN WIND CORRIDOR FROM KRKS TO KCPR BEGINS FAIRLY EARLY...TURNING WEST AFTER 21Z AS ANOTHER ROUND OF SHOWERS AND THUNDERSTORM MOVE INTO THE WEST AROUND 18Z SPREADING EAST THROUGH 00Z WEDNESDAY. AGAIN THE BEST CHANCE FOR RAIN AND HAIL WILL BE ACROSS THE NORTH...VCNTY KCOD KWRL AND KBYG...WHILE HIGHER BASED THUNDERSTORMS IN CENTRAL AREAS WILL PRODUCE VERY STRONG OUTFLOW WINDS...IT WILL LIKELY BE TOO DRY FOR STORMS VCNTY KRKS AND KCPR. STORMS WILL EXIT THE AREA AFTER 03Z LEAVING BEHIND A FEW HIGHER CLOUDS AND LIGHT WINDS. .FIRE WEATHER... A SERIES OF SYSTEMS WILL BRING SHOWERS AND THUNDERSTORMS ACROSS NORTHERN AND WESTERN WYOMING OVER THE NEXT FEW DAYS. TUESDAY AND WEDNESDAY MAY SEE SOME STRONGER STORM DEVELOPMENT ACROSS JOHNSON COUNTY. THESE STRONGER WIND MAY HAVE SIGNIFICANT AND ERRATIC WIND WITH INCREASED HAIL...IN ADDITION TO PERIODS OF HEAVY RAINFALL. AREAS OF SOUTHERN WYOMING WILL AGAIN HAVE A WARM AND GENERALLY DRY DAY...WITH HUMIDITY AGAIN DIPPING INTO THE SINGLE DIGITS THIS AFTERNOON. HOWEVER...TEMPERATURES WILL COOL OVER THE NEXT COUPLE OF DAYS UNDER THE INFLUENCE OF THESE SYSTEMS. && .RIW WATCHES/WARNINGS/ADVISORIES...NONE. && SHORT TERM...SKRBAC LONG TERM...BRAUN AVIATION...SKRBAC FIRE WEATHER...SKRBAC
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 126 PM MDT TUE JUN 11 2013 WYZ001>020-022>030-121200- 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- 126 PM MDT TUE JUN 11 2013 ...SEVERE THUNDERSTORM WATCH FOR JOHNSON COUNTY UNTIL 9 PM MDT... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE ACROSS JOHNSON COUNTY AND THE BIG HORN BASIN THIS AFTERNOON AND EVENING. LARGE HAIL AND DAMAGING WINDS COULD OCCUR WITH A FEW STORMS IN THESE AREAS. VERY HEAVY RAINFALL COULD ALSO OCCUR...WITH LOCALIZED FLASH FLOODING POSSIBLE. BURN SCAR AREAS ARE PARTICULARLY SUSCEPTIBLE TO FLASH FLOODING...INCLUDING THE GILEAD BURN SCAR IN NORTHWEST JOHNSON COUNTY. ELSEWHERE...THE PRIMARY HAZARD FROM THUNDERSTORMS WILL BE VERY GUSTY WINDS. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY WEDNESDAY...WIDELY SCATTERED MOUNTAIN THUNDERSTORMS WITH ISOLATED THUNDERSTORMS ACROSS THE NORTH HALF OF THE REGION. SOME STORMS MAY BECOME STRONG TO SEVERE IN THE AFTERNOON...ESPECIALLY ACROSS THE NORTHERN THIRD OF THE STATE. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ENCOURAGED TO REPORT THUNDERSTORM WIND GUSTS OVER 40 MPH...ANY HAIL...FLOODING...OR ANY DAMAGE. THANK YOU. TEAM RIVERTON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 146 PM MDT TUE JUN 11 2013 WYZ003-005>007-112030- CODY FOOTHILLS WY-OWL CREEK AND BRIDGER MOUNTAINS WY-SOUTHEAST BIG HORN BASIN WY-SOUTHWEST BIG HORN BASIN WY- 146 PM MDT TUE JUN 11 2013 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN WASHAKIE...NORTHERN HOT SPRINGS AND EXTREME SOUTHEASTERN PARK COUNTIES UNTIL 230 PM MDT... AT 142 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR HWY JCT 431 AND 120...OR 18 MILES SOUTHEAST OF MEETEETSE...MOVING EAST AT 15 MPH. HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM. THIS STORM WILL BE NEAR... STATE HWY 120 MILE MARKER 30 AND STATE HWY 171 AROUND 155 PM MDT. HWY JCT 171 AND 120 AROUND 210 PM MDT. STATE HWY 431 MILE MARKER 20 AND SAND DRAW RD AROUND 225 PM MDT. LOWER COTTONWOOD CREEK RD AROUND 230 PM MDT. IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A STURDY BUILDING. REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN RIVERTON AT 1-800-211-1448. LAT...LON 4415 10818 4377 10830 4391 10875 4416 10862 TIME...MOT...LOC 1946Z 283DEG 12KT 4397 10860 SKRBAC
The Riverton/Lander radar (KRIW), 139 km away, was scanning. The volume nearest the first event began at 21:36 UTC.
2 hail. Local standard time, as filed.
A trained spotter reported nickel sized hail along the Nowood River Road northwest of Ten Sleep.
A spotter reported hail from pea to penny size a few miles north of Buffalo.
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, June 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: 447074, 447075.