Thunderstorms fired across much of western and central Wyoming on the afternoon and evening of August 1. The strongest storm formed east of the Absaroka Range and become severe as it moved east into Big Horn County.
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.
Thunderstorms fired across much of western and central Wyoming on the afternoon and evening of August 1. The strongest storm formed east of the Absaroka Range and become severe as it moved east into Big Horn County. This storm caused crop damage and produced penny sized hail near Hyattville. The storm then took on supercell characteristics as it moved into Johnson County. Hail one inch in diameter was reported and winds were estimated at 60 to 70 mph at a rural ranch.
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 Aug 1, 2:07 PM MST, 1 hour 34 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 307 PM MDT THU AUG 1 2013 .SHORT TERM...TONIGHT THROUGH FRIDAY THE BIG PICTURE...STILL THE BOOKS BETWEEN TWO BOOK END LOWS ALOFT...WITH RIDGE AXIS CUTTING RIGHT UP THROUGH THE CENTER OF THE STATE FROM SOUTH TO NORTH...OR NEARLY SO. LAST NIGHT'S SW AXIS ROTATING THRU RIDGE...EXTENDING FROM OUR NERN CWA...STRETCHING DOWN TO SWRN WY THIS MORNING...WITH SHOWERS AND THUNDER ONGOING FROM NRN BIG HORN BASIN TO THE EAST AND OVER NRN JOHNSON COUNTY. ADDITIONALLY...SW ROUNDING BASE OF WRN NW CONUS TROF CURRENTLY EXITING NRN CA AND ENTERING NW NVSW ID. DRYING CAN ALREADY BE SEEN MOVING ACROSS THE CWA FROM THE SW FROM OUT OF THE GREAT BASIN. AT THE SFC...LOW PRESSURE OFF TO THE WEST CENTERED OVER THE UT/ID BORDER REGION THIS MORNING...AND SEEMINGLY PERPETUAL HIGH CENTERED OVER CNTRL CO. NEARLY STATIONARY FRONT DRAPED ACROSS SRN WY FROM WEST TO EAST...MARKING A POSSIBLE FOCUS AND NRN EXTENT FOR PRECIP CHCS IN THE SRN CWA...WITH ANOTHER FRONT/TROF BOUNDARY TO OUR NW IN WRN WA ATTM...EXPECTED TO APPRAOCH OUR NWRN REGION OF THE YELLOWSTONE AREA THIS EVENING. BOTH POSITIONS OF UPR AND LL PRESSURE PATTERNS MAKING FOR INTERESTING FLOW/MOISTURE REGIME THRU DEPTH. TODAY/TONIGHT...AS ALLUDED TO ABOVE...DEEPER RELATIVELY DRY SWRLY FLOW TAKING OVER MUCH OF THE REGION TODAY. HOWEVER THERE AREA A COUPLE OF AREAS THAT WILL BE PRIVY TO MORE AVAILABLE MOISTURE THAT WILL NOT HAVE BEEN SCOURED OUT. 1 SOMEWHAT BETTER LL MOISTURE POOLING THAT WILL BE TRAPPED AND/OR REINFORCED BY BUILDING SFC LOW PRESSURE INTO CNTRL WY IN THE NRN BIG HORN BASIN...TRAPPED ON THE WEST BY THE MOUNTAINS...AND WHICH WILL ALSO ALLOW A SERLY TO ERLY LL PUSH INTO JOHNSON AND NRN NATRONA COUNTIES. 2 MID LVL MOISTURE INFLITRATING OUR NW CORNER AHEAD OF TONIGHT'S SW...AND SOME MODEST MOISTURE RETURN FROM OUR FRIENDS AND FLOW PATTERN TO THE SOUTH. SO NATURALLY THESE WILL BE THE AREAS MOST HIGHLIGHTED TODAY AND THIS EVENING. OTHERWISE...OVERNIGHT TONIGHT IF SFC LOW CAN PROGRESS FAR ENOUGH E OR NE INTO CWA...AND SW MENTIONED ABOVE ARRIVES FROM THE WRN GREAT BASIN AREA ON TIME...BETTER SHOWER AND SOME THUNDER WILL BE POSSIBLE INTO THE UPR GREEN RIVER BASIN...WIND RIVER MOUNTAINS AND PERHAPS EVEN INTO...ALTHOUGH TO A LESSER EXTENT...THE WIND RIVER BASIN IN THE AFTER MIDNIGHT PERIOD. WITH GOOD SOLAR INSOLATION TODAY AND MODERATELY COOL UPPER LEVELS WILL PROVIDE STEEP TO VERY STEEP LAPSE RATES ACROSS THE CWA...BUT WE HAVE BEEN THERE BEFORE. ONE THING THAT WILL KEEP CONVECTION FROM HAPPENING EVERYWHERE TODAY IS THE SW RIDGE THAT IS CURRENTLY ON ITS WAY THRU THE STATE FROM THE SW...PUSHING INTO CNTRL WY ATTM...BOTH WARMING AND DRYING DURING THE DAY. MAIN FOCUS FOR STRONG OR SEVERE STORMS WILL BE IN AND NEAR JOHNSON COUNTY THIS AFTERNOON...WHICH SEEM TO HAVE THE BEST OF THE BEST AS FAR AS OVERALL DYNAMICS...INCLUDING ML CAPE NEAR 750-1000 J/KG AND EFFECTIVE SHEAR WITH THIS CAPE RUNNING 35 TO 40 KTS. THERE ALSO SEEMS TO BE CONVERGENCE BOUNDARY THAT HAS SET UP FROM MORNING CONVECTION THAT TRACKED THROUGH THE NRN PORTION OF THE COUNTY THIS MORNING...RIGHT NOW LOCATED FROM EAST TO WEST NEAR BUFFALO WY. PROBLEM ATTM WILL BE THAT IT WILL HAVE TO HAPPENED FAIRLY SOON AS UPR LEVEL WARMING IS STARTING TO EDGE IN THERE TOO...OR WAIT UNTIL EARLY THIS EVENING AHEAD SO IF THE CAP WILL POP...COULD BE A BIG IF...THIS AFTERNOON OR GET A STORM OFF THE BIG HORNS...CONCERNS WILL INCLUDE HEAVY RAIN WITH PWS OVER AN INCH HERE...HAIL TO AN INCH IN SIZE...WINDS APPROACHING SEVERE...MAYBE STRONGER IN A MICROBURST SITUATION...AND EVEN FUNNEL CLOUDS/ETC. IN BACKED SFC FLOW AND NICE VEERING ABOVE. TONADOES WILL BE TOUGH TO GET ON THE GROUND AS LCLS ARE A BIT TOO HIGH. AS EVENING GETS HERE...LOOK FOR STORMS ON THE STRONGER SIDE MAINLY NORTH OF A DUBOIS TO WORLAND TO BUFFALO THEN EAST LINE. SMALL HAIL AND GUSTY WINDS TO 40 MPH CANBE EXPECTED WITH THESE. WILL ALSO HAVE TO WATCH THE NORTHWEST CORNER OF OF THE CWA...THROUGH YELLOWSTONE...TO SEE IF SFC FROM PUSHES INTO THE AREA WHILE NOCTURNAL SW MOVES THROUGH...STRONGER MORE LONG LIVED STORMS COULD MOVE THROUGH THE PARK ALONG AND NORTH OF THIS BOUNDARY. FRIDAY...MUCH OF CWA WILL BE STORM FREE THIS DAY WITH ISOLATED AREAS FOR STORMS OCCURRING MAINLY WELL NORTH NEAR THE MT/WY BORDER...THE HIGHER NORTHERN MOUNTAINS INCLUDING THE BIG HORNS...AND AGAIN NORTHERN JOHNSON COUNTY COULD PRODUCE. HAVE KEPT THE VERY SMALL CHCS CURRENTLY IN THE FCST THAT TRAIL OFF TO THE SOUTH OF THESE AREAS AS MUCH WILL BE DETERMINED BY FINAL SET UP OF BOUNDARIES FROM TODAY'S STORMS AND JUST WHERE EXITING SFC LOW AND TRAILING FRONT GOES. .LONG TERM...FRIDAY NIGHT THROUGH THURSDAY NIGHT FRIDAY NIGHT THROUGH MONDAY SHOW LITTLE CHANGE IN THE MAIN UPPER AIR PATTERN WITH DRY AND WARMER SOUTHWEST FLOW ALOFT IN THE SOUTH AND WEST BATTLING COOLER AND MOISTER EST NORTHEAST LOW LEVEL FLOW IN THE EAST AND NORTH. EXPECT ISOLATED CONVECTION TO FIRE OFF OVER THE CENTRAL AND NORTHWEST MOUNTAINS IN THE SOUTHWEST FLOW AND ADVECT NORTHEAST AND INTENSIFY IN COVERAGE AND STRENGTH WHEN COLLIDING WITH THE MOISTER AIR MASS AND LOW LEVEL CONVERGENCE BOUNDARY. CONVECTION COULD LINGER PAST MIDNIGHT IN THE NORTH AND EAST THROUGH THIS PERIOD. BOTH THE GFS AND ECMWF ADVERTISE A PATTERN CHANGE BEGINNING TUESDAY WITH A COLD FRONT COMING SOUTH AND WEST FROM MONTANA AND THE DAKOTAS AS AN UPPER LEVEL LOW DEEPENS OVER CENTRAL CANADA AND MOVES SOUTH SOUTHEAST TOWARDS THE NORTHERN PLAINS AND GREAT LAKES. ALSO A LOW OFF THE CENTRAL CALIFORNIA COAST WRAPS UP TURNING THE SOUTHWEST FLOW OVER THE GREAT BASIN SO THE FLOW MOVES FARTHER WEST OF WYOMING INTO OREGON AND SOUTHERN IDAHO. THIS WILL ALLOW MORE SUBTROPICAL MOISTURE OVER NEW MEXICO AND EASTERN ARIZONA TO MOVE NORTH REPLACING THE DRY SLOT. BY WEDNESDAY BOTH THE GFS AND ECMWF BECOME QUITE WET ALONG AND NORTH OF THE CONTINENTAL DIVIDE WITH SIGNIFICANT COOLING IN THE NORTH AND EAST. THE UPPER 50S THE ECMWF MOS FORECASTS AT BYG SEEMS TO BE A TAD TOO COOL WITH THE GFS MEX IN THE MID 70S MAYBE A BIT TOO WARM. COULD SEE LOWER 70S BUT NOT UPPER 50S FOR HIGHS WEDNESDAY OR THURSDAY. BOTH MODELS HAVE SIGNIFICANT BULLS EYES OF QPF AND EXPECT THEY ARE BOTH WELL OVERDONE IN COVERAGE OF HEAVY PRECIPITATION. && .AVIATION.../00Z ISSUANCE/ VFR CONDITIONS WILL PREVAIL THROUGH 12Z FRIDAY. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO FORM OVER THE NORTHWEST... NORTH...AND NORTHEAST...CONTINUING IN AREAS OCCASIONALLY THROUGH 12Z FRIDAY MORNING BEFORE CLEARING. A COUPLE OF THESE STORMS COULD BE STRONG...WITH GUSTY WINDS TO 50 MPH AND HAIL TO 3/4 INCH. LARGER HAIL MAY BE POSSIBLE ACROSS EASTERN WYOMING TONIGHT. OTHERWISE...ISOLATED STORMS WILL BE FOUND TO THE SOUTH NEAR KRKS...BUT WILL TAKE WELL INTO THE EVENING BEFORE ANY OF THE CENTRAL TERMINALS ARE AFFECTED. AGAIN...SOME THUNDERSTORMS MAY BRIEFLY REDUCE MVFR CONDITIONS DUE TO LOWERED VISIBILITY AND LOWERED CEILINGS. ALL TERMINALS HAVE A HIGH LIKELIHOOD ON FRIDAY TO BE RAIN FREE AS ATMOSPHERE BOTH STABILIZES AND DRIES OUT. && .FIRE WEATHER... HIGH TEMPERATURES ARE GENERALLY RUNNING SOME 2 TO 8 DEGREES HIGHER TODAY THAN ON WEDNESDAY...BUT WILL COOL BY SOME 3 TO 5 DEGREES ON FRIDAY. ISOLATED TO SCATTERED CHANCES FOR THUNDERSTORMS WILL BE POSSIBLE ACROSS THE NORTHERN DISPATCH ZONES...WITH ISOLATED CHANCES ALSO BE POSSIBLE OVER SWEETWATER COUNTY AGAIN...MUCH AS YESTERDAY. THERE WILL BE LITTLE CHANCE IF ANY IN BETWEEN DURING THE DAY AS UPPER LEVEL RIDGING PROCEEDS...USABLE MOISTURE BECOMES SPLIT AND UPPER LEVELS WARM. THE MAIN CONCERN AT THIS TIME WILL BE THE GUSTY ERRATIC WINDS TO 40 MPH CAN BE EXPECTED AT TIMES WITH SOME OF THESE STORMS. STRONG TO SEVERE POTENTIAL EXISTS IN ZONE 281 TODAY IF A THUNDERSTORM DEVELOPS THIS AFTERNOON OR EVENING. OTHER STRONGER STORMS MAY BE EXPECTED OVER ZONES 140...275...276 AND 281 THIS AFTERNOON AND THROUGH THE EVENING. FRIDAY...DRY WEST TO SOUTHWEST WINDS WILL INFILTRATE FURTHER INTO THE STATE FROM THE WEST...EFFECTIVELY CUTTING OF MOST PRECIPITATION CHANCES EXCEPT FOR PORTIONS OF ZONE 281. FORECAST RH VALUES AND WINDS CONTINUE LOOK TO HOLD JUST HIGH ENOUGH TO PRECLUDE EXTREME FIRE WEATHER CONCERNS...BUT WILL HAVE TO WATCH THE ALL ZONES...ESPECIALLY THOSE IN THE SOUTHERN PART OF THE STATE...AS THERE MAY BE SHORT PERIODS WHERE FIRE WEATHER PARAMETERS BECOME CRITICAL. WILL ALSO MONITOR CLOSELY THROUGH THE WEEKEND AS A GENERAL DRYING TREND CONTINUES OVER THE SOUTHERN AND SOUTHWESTERN ZONES. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...BRAUN LONG TERM...C.BAKER AVIATION...BRAUN FIRE WEATHER...BRAUN
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 500 AM MDT THU AUG 1 2013 WYZ001>020-022>030-021100- 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- 500 AM MDT THU AUG 1 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT ISOLATED TO SCATTERED THUNDERSTORMS...ESPECIALLY OVER THE NORTH. SOME STORMS COULD BE STRONG ACROSS THE NORTH AND EAST. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY FRIDAY...NEAR CRITICAL FIRE WEATHER CONDITIONS POSSIBLE ACROSS THE SOUTHWEST. SATURDAY...A FEW STRONG THUNDERSTORMS POSSIBLE ACROSS EAST CENTRAL WYOMING. WEDNESDAY...ISOLATED TO SCATTERED THUNDERSTORMS ACROSS MOST AREAS. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ENCOURAGED TO REPORT WINDS OVER 45 MPH...AND HAIL OF ANY SIZE. THANK YOU! TEAM RIVERTON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 236 PM MDT THU AUG 1 2013 WYZ003-004-006-012115- CODY FOOTHILLS WY-NORTH BIG HORN BASIN WY-SOUTHEAST BIG HORN BASIN WY- 236 PM MDT THU AUG 1 2013 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN BIG HORN AND NORTHWESTERN WASHAKIE COUNTIES IN NORTH CENTRAL WYOMING...AND EASTERN PARK COUNTY IN NORTHWEST WYOMING UNTIL 315 PM MDT... AT 234 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR STATE HWY 120 MILE MARKER 60...OR NEAR MEETEETSE...MOVING NORTHEAST AT 30 MPH. HAIL UP TO THREE-EIGHTS INCH IN DIAMETER AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. THIS STORM WILL BE NEAR... STATE HWY 30 MILE MARKER 120 AROUND 315 PM MDT. IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A STURDY BUILDING. IN ADDITION...THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS... FOR ADDITIONAL INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE. BRIEF HEAVY RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY. REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN RIVERTON AT 1-800-211-1448. LAT...LON 4472 10841 4409 10805 4410 10888 4426 10898 TIME...MOT...LOC 2036Z 247DEG 27KT 4422 10880 BRAUN
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 238 PM MDT THU AUG 1 2013 WYZ028>030-012200- EAST SWEETWATER COUNTY-FLAMING GORGE-ROCK SPRINGS AND GREEN RIVER- 238 PM MDT THU AUG 1 2013 ISOLATED THUNDERSTORMS WILL BE MOVING NORTHEAST AT AROUND 20 MPH THROUGH THE AREA ALONG AND SOUTH OF INTERSTATE 80 THROUGH 400 PM. GUSTY WINDS BETWEEN 30 AND 40 MPH...BRIEF HEAVY RAIN AND FREQUENT LIGHTNING WILL BE THE MAIN THREATS FROM THE STORMS. SEEK SAFE SHELTER INDOORS WHEN STORMS APPROACH. JB
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 311 PM MDT THU AUG 1 2013 WYZ003-004-006-012200- CODY FOOTHILLS WY-NORTH BIG HORN BASIN WY-SOUTHEAST BIG HORN BASIN WY- 311 PM MDT THU AUG 1 2013 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN BIG HORN AND NORTHWESTERN WASHAKIE COUNTIES IN NORTH CENTRAL WYOMING...AND EASTERN PARK COUNTY IN NORTHWEST WYOMING UNTIL 400 PM MDT... AT 308 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 11 MILES EAST OF STATE HWY 120 MILE MARKER 60... OR 13 MILES NORTHEAST OF MEETEETSE...MOVING EAST AT 30 MPH. HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. THIS STORM WILL BE NEAR... STATE HWY 30 MILE MARKER 110 AROUND 355 PM MDT. IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A STURDY BUILDING. IN ADDITION...THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS... FOR ADDITIONAL INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE. BRIEF HEAVY RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY. REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN RIVERTON AT 1-800-211-1448. LAT...LON 4470 10821 4410 10787 4413 10871 4430 10877 TIME...MOT...LOC 2111Z 256DEG 24KT 4424 10861 BRAUN
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 330 PM MDT THU AUG 1 2013 WYZ030-012200- EAST SWEETWATER COUNTY WY- 330 PM MDT THU AUG 1 2013 ...SIGNIFICANT WEATHER ADVISORY FOR EASTERN SWEETWATER COUNTY UNTIL 400 PM MDT... AT 327 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 12 MILES NORTHEAST OF ADOBE TOWN RIM...OR 25 MILES SOUTHWEST OF WAMSUTTER...MOVING NORTHEAST AT 30 MPH. HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 45 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH FREQUENT DANGEROUS LIGHTNING. THIS STORM WILL BE NEAR... RURAL EASTERN SWEETWATER COUNTY THROUGH 400 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 4123 10824 4139 10834 4164 10793 4125 10792 TIME...MOT...LOC 2130Z 245DEG 26KT 4135 10817 C. BAKER
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 339 PM MDT THU AUG 1 2013 WYZ019-028-030-012230- EAST SWEETWATER COUNTY WY-GREEN MOUNTAINS AND RATTLESNAKE RANGE WY-ROCK SPRINGS AND GREEN RIVER WY- 339 PM MDT THU AUG 1 2013 ...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL SWEETWATER COUNTY UNTIL 430 PM MDT... AT 337 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 5 MILES NORTH OF I80 EXIT 111...OR 8 MILES NORTHEAST OF ROCK SPRINGS...MOVING EAST AT 60 MPH. HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 45 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH FREQUENT DANGEROUS LIGHTNING. THIS STORM WILL BE NEAR... SUPERIOR AND I80 EXIT 122 AROUND 345 PM MDT. POINT OF ROCKS AROUND 355 PM MDT. THIS INCLUDES INTERSTATE 80 IN WYOMING BETWEEN MILE MARKERS 109 AND 151. 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 4211 10843 4165 10820 4157 10917 4176 10928 TIME...MOT...LOC 2139Z 251DEG 51KT 4170 10909 C. BAKER
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 354 PM MDT THU AUG 1 2013 WYZ004-006-008-012300- BIGHORN MOUNTAINS WEST WY-NORTH BIG HORN BASIN WY-SOUTHEAST BIG HORN BASIN WY- 354 PM MDT THU AUG 1 2013 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN BIG HORN AND NORTHERN WASHAKIE COUNTIES IN NORTH CENTRAL WYOMING UNTIL 500 PM MDT... AT 354 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 11 MILES WEST OF HWY 16/20/789 MILE MARKER 190... OR 15 MILES SOUTHWEST OF BASIN...MOVING EAST AT 25 MPH. HAIL UP TO THE SIZE OF NICKELS AND WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. THIS STORM WILL BE NEAR... HWY 16/20/789 MILE MARKER 190 AROUND 420 PM MDT. MANDERSON AND STATE HWY 432 MILE MARKER 10 AROUND 430 PM MDT. HWY 16/20/789 MILE MARKER 180 AROUND 435 PM MDT. STATE HWY 31 MILE MARKER 10 AROUND 445 PM MDT. STATE HWY 31 MILE MARKER 20 AND HYATTVILLE AROUND 500 PM MDT. IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A STURDY BUILDING. IN ADDITION...THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS... FOR ADDITIONAL INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE. BRIEF HEAVY RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY. REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN RIVERTON AT 1-800-211-1448. LAT...LON 4461 10756 4400 10750 4414 10838 4432 10839 TIME...MOT...LOC 2154Z 267DEG 23KT 4423 10826 BRAUN
The Riverton/Lander radar (KRIW), 143 km away, was scanning. The volume nearest the first event began at 22:39 UTC.
3 thunderstorm wind, 2 hail. Local standard time, as filed.
A trained spotter estimated wind gusts of 60 mph.
Wind-driven hail up to the size of pennies caused corn crop damage west of Hyattville.
Wind gusts at a ranch near the Powder River were estimated to be 60 to 70 mph.
Hail up to the size of quarters was reported at a rural eastern Johnson County ranch.
A collapsing shower produced a wind gust of 58 mph at the Lander Airport.
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, August 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: 458770, 474574, 458771, 474567, 458772.