Thunderstorms developed over the Wind River Mountains and moved into the Lander Foothills and Wind River Basin. Strong winds aloft were brought to the surface by thunderstorm downdrafts.
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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.
Thunderstorms developed over the Wind River Mountains and moved into the Lander Foothills and Wind River Basin. Strong winds aloft were brought to the surface by thunderstorm downdrafts. Wind speeds in and near the Lander Foothills topped out at 62 to 64 mph. The wind spread northeast across the Wind River Basin with a peak wind of 59 mph clocked at the Riverton NWS office.
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 Apr 14, 10:55 AM MST, 1 hour 30 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 1155 AM MDT THU APR 14 2016 .SHORT TERM...TODAY THROUGH SATURDAY NIGHT IMAGERY CONTINUES TO SHOW SPLIT FLOW NOW ACROSS THE CNTRL CONUS WITH RIDGE OVR LOW....WHILE THE WRN CONUS IS FEELING THE INFLUENCE OF A RELATIVELY STRONG UPSTREAM TROF COMING INTO THE PAC NW. THE JET ASSOCIATED W/ THIS TROF CURRENTLY STRETCHES FROM UNDER THE BASE OF THE TROF...THRU NRN CA/NRN NV/AND INTO CNTRL CNTRL ID. SFC HAS GENERALLY WEAK P GRAD ACROSS THE WEST ATTM...WITH WEAK LEE SIDE TROFFING ACROSS ERN WY AND A WEAK SFC FRONT ACROSS CNTRL WY. LIGHT RAIN SHOWER ACTIVITY ACROSS SOUTHWEST WY INCLUDING THE UPR GREEN BASIN...WITH SOME CLEARING FURTHER TO THE WEST. VERY COMPLEX WX SYSTEM CONTINUES OVER THE NEXT FEW DAYS. TODAY...INCREASING ASCENT WITH UPPER DIFFLUENCE AHEAD OF THE NEXT MAJOR TROF WILL ALLOW FOR INCREASING PRECIP WITH CONVECTIVE ATTRIBUTES ACROSS WRN WY AS VIGOROUS FRONTOGENESIS TAKES PLACE JUST TO THE WEST...ARRIVING NEAR THE WRN BORDER BY MID-DAY. CYCLOGENESIS WILL ALSO PROCEED ACROSS NRN/NERN WY TODAY...WITH SECONDARY CYCLOGENESIS JUST BEGINNING TO THE SOUTH ACROSS ERN CO. AS THE FRONT PUSHES INTO THE WEST...PRECIP POTENTIAL WILL INCREASE QUICKLY...MOVING E OF THE DIVIDE BY THIS AFTERNOON...THEN MOSTLY OUT OF WY AFTER MIDNIGHT TONIGHT. SNOWFALL POTENTIAL OUT WEST WILL BE GREATEST THIS MORNING THRU EARLY AFTERNOON WITH TOTAL ACCUMULATIONS BY THIS EVENING REACHING TO 6 INCHES OVER THE HIGHER MOUNTAINS...AND FROM A HALF TO 2 INCHES IN THE VALLEYS. E OF THE DIVIDE...SHOWERS AND EMBEDDED THUNDERSTORMS WILL RULE BY MID TO LATE AFTERNOON AND INTO THE EARLY EVENING PERIOD. THUNDERSTORMS WILL GENERALLY HAVE MODEST MOISTURE AND LOW CAPE TO WORK WITH...BUT MODEST TO HIGH SHEAR KEEPING THINGS GOING ANYWAY...ESPECIALLY JUST AHEAD OF AND AT THE FRONT WHERE SFC BACKING OCCURS. STRONGER STORMS OF THE DAY WILL LIKELY BE FOUND FROM CNTRL TO ERN FREMONT COUNTY AND INTO WRN NATRONA COUNTY...THEN NORTH ACROSS JOHNSON COUNTY...WITH SMALL HAIL AND VERY GUSTY WINDS POSSIBLE. ATTM...JOHNSON COUNTY LOOKS TO HAVE THE BEST...BUT STILL LOW PROBABILITY...CHANCE FOR SUSTAINED STORM ROTATION AND THEREFORE THE BEST CHANCE FOR AN ISOLATED SVR STORM OR TWO...WITH (NEAR) LARGE HAIL...STRONG WINDS...AND EVEN A FUNNEL CLOUD OR BRIEF TORNADO. OTHERWISE...HEAVIER SHOWERS MOVE E INTO THE HIGH/CNTRL PLAINS OVERNIGHT WITH THE FRONT AS A LOSS OF ASCENT OCCURS ACROSS THE WEST WHILE THE TROF AXIS APPROACHES AND HIGH P BUILDS OVR THE REGION. AS MOST OF THE COLDER AIR WILL NOT ARRIVE UNTIL AFTER FRONTAL PASSAGE...RAIN MIXED WITH SNOW OR JUST SOME WET SNOW WILL NOT ARRIVE UNTIL AFTER MIDNIGHT FOR MOST OF CNTRL/SRN WY. SO...SNOW ACCUMULATION SHOULD RANGE FROM A HALF INCH OR LESS FOR MOST LOCATIONS...TO PERHAPS AN INCH ACROSS SRN SWEETWATER COUNTY. THRU FRI MORNING...ANOTHER INCH OR SO OF SNOW COULD FALL ACROSS SRN SWEETWATER COUNTY. OTHERWISE...THE UPR TROF NOW LOOKS TO DEVELOP TWO CLOSED CIRCULATIONS...ONE ACROSS MT AND THE OTHER OVR THE SW CONUS...WITH STILL TWO AREAS OF VIGOROUS CYCLOGENESIS LIKELY TO OCCUR...ONE TO THE S OVER SERN COLORADO/NRN NM...AS THE BASE OF THE TROF AND JET SWINGS TO THE WEST OF THAT AREA....THE OTHER WELL TO THE NE INTO WRN ND. AN ELONGATED PLUME OF MOISTURE WILL BE CO- LOCATED WITH A WCB FROM/ACROSS THE SRN ROCKIES...NE ALL THE WAY TO MINNESOTA. WHILE A RATHER VIGOROUS RETURN OF MOISTURE CAN STILL BE EXPECTED NEAR OUR FA...MOST OF IT LOOKS TO EXIST ACROSS PORTIONS OF ERN/SERN WY FROM LATE FRIDAY AFTERNOON TO THE END OF THE FCST. THE SECONDARY CIRCULATION OVR MT WILL ALLOW FOR ONLY MODEST CHCS FOR PRECIP ACROSS THE NRN MOUNTAINS AND ADJACENT AREAS OVR THE SAME PERIOD WITH MUCH LESS MOISTURE TO WORK WITH. TO THE SOUTH...THE AREA EAST OF A LINE FROM NEAR EVANSTON TO MIDWEST...NORTH OF THE NEARLY STATIONARY FRONT...WILL BE THE AREA WITH THE BEST OVERALL PRECIP POTENTIAL UNDER THE AREA OF GREATEST ASCENT OVR WY. WHILE RAIN OR RAIN MIXED WITH SNOW WILL BE MOST PREVALENT FOR MOST OF PRECIP FRIDAY AFTERNOON...BY FRI EVENING...CHANGEOVER TO ALL SNOW WILL PROBABLY OCCUR FAIRLY QUICKLY WITH H7 TEMPS QUICKLY DECREASING TO -5 TO -6 DEG C. OVERNIGHT FRIDAY THRU SAT MORNING...CURRENTLY EXPECTING GENERALLY LESS THAN AN INCH FOR MOST LOCATIONS E AND W OF THE DIVIDE...BUT ANOTHER 1 TO 2 INCHES POSSIBLE FOR AREAS BETWEEN ERN SWEETWATER...AND SRN NATRONA COUNTY...1 TO 3 INCHES OVR THE BIGHORN MOUNTAINS...AND UP TO 4 INCHES OVER CASPER MOUNTAIN. SAT THRU SAT NIGHT...WITH SOME ADVANCEMENT OF THE UPR TROF TO THE EAST...THE MID LVL SFC FRONT...ALTHOUGH STILL NEARLY STATIONARY...SHOULD SAG S AND E SOME...KEEPING LOW END CHCS FOR PRECIP...MIXED RAIN/SNOW...TO ALL SNOW...ACROSS SRN AND ECNTRL WY...WITH BEST CHCS OCCURRING FROM EXTREME ERN SWEETWATER COUNTY ACROSS SRN NATRONA COUNTY. HEAVIEST SNOWFALL WILL BE LOCATED OVR CYS'S AREA FOR THE MOST PART...HOWEVER SWEETWATER...ERN FREMONT...AND NATRONA COUNTIES MAY ALL SEE FROM A HALF TO 2 INCHES OF HEAVY WET SNOWFALL BY SUNRISE SUNDAY. .LONG TERM...SUNDAY THROUGH THURSDAY SYNOPSIS...UPPER LOW PRESSURE SYSTEM OVER THE FOUR CORNERS AREA WILL GRADUALLY WEAKEN AND MOVE OUT INTO THE PLAINS BY MIDWEEK. CHANCES OF RAIN AND SNOW SHOWERS WILL CONTINUE THROUGH MONDAY MAINLY ALONG AND SOUTH OF A CASPER TO ROCK SPRINGS LINE WITH DRY AND MILDER CONDITIONS ACROSS THE NORTHWEST HALF OF THE AREA. DRY AND MILDER WEATHER UNDER A RIDGE OF HIGH PRESSURE WILL PREVAIL TUESDAY THROUGH THURSDAY. DISCUSSION...UPPER LOW PRESSURE SYSTEM OVER NORTHWEST NEW MEXICO SUNDAY MORNING IS FORECAST BY ALL MEDIUM-RANGE GUIDANCE TO GRADUALLY FILL AND FRAGMENT SUNDAY AND MONDAY UNDER UPPER RIDGE FOLDING ACROSS THE NORTHERN ROCKIES. SURFACE HIGH PRESSURE OVER THE NORTHERN PLAINS WILL KEEP COOL LOW LEVEL NORTHEAST FLOW ACROSS THE CENTRAL AND SOUTH THROUGH MONDAY. GFS AND ECMWF SHOW SOME DIFFERENCES IN PRECIPITATION PLACEMENT AS UPPER LOW FRAGMENTS INTO CENTRAL ROCKIES WITH ECMWF WRAPPING MORE PRECIPITATION BACK INTO EAST CENTRAL AND SOUTHWEST WYOMING ON MONDAY. THERE IS LOW CONFIDENCE IN MODELS DEPICTION OF A NICE NEAT COMMA HEAD WRAPPING BACK FROM LINE OF CONVECTION ACROSS THE SOUTHERN/CENTRAL PLAINS AS THINGS WILL INEVITABLY GET A LITTLE MESSIER. FORECAST PUTS HIGHER CHANCE POPS ALONG AND SOUTH OF A CASPER TO ROCK SPRINGS LINE ON SUNDAY WITH AN OVERALL DECREASING TREND FROM THE SOUTHWEST SUNDAY NIGHT AND MONDAY. TEMPERATURES ALOFT WILL REMAIN COLD ENOUGH FOR MOSTLY SNOW FROM EASTERN SWEETWATER COUNTY ACROSS NATRONA COUNTY INTO MONDAY MORNING...BUT SNOWFALL AMOUNTS SHOULD BE LIGHT. HIGH OVER LOW PATTERN IS EXPECTED TO SLOWLY PROGRESS INTO THE HIGH PLAINS ON TUESDAY WITH WARMER AIRMASS AND MID-APRIL SUN BRINGING MILDER MORE SPRING-LIKE TEMPERATURES INTO THE SOUTH AND EAST CENTRAL. GFS IS QUICKER TO FLATTEN UPPER RIDGE OVER THE ROCKIES ON THURSDAY...BRINGING THE FIRST IN A SERIES OF NORTHERN STREAM SHORTWAVES IN SPLIT FLOW INTO THE NORTHERN ROCKIES. ECWMF SHOWS SLOWER PROGRESSION...WEAKER NORTHERN STREAM IN THIS SPLIT FLOW. FORECAST BRINGS SLIGHT CHANCE POPS INTO NW MTNS THURSDAY. WARMING TREND WILL CONTINUE ACROSS THE REST OF THE AREA WITH MOST LOWER CENTRAL BASINS SEEING HIGHS IN THE 70S ON THURSDAY. && .AVIATION.../18Z ISSUANCE/ WEST OF THE CONTINENTAL DIVIDE...KJAC/KRKS/KPNA/KBPI ROUTES A COLD FRONT CONTINUES TO MOVE THROUGH THE AREA...AND WILL CONTINUE THROUGH 00Z THIS EVENING FOR THE WESTERN TERMINALS. SOME TERMINALS HAVE ALREADY SEEN THE FRONT PASSAGE...WITH THE RESULTANT SHOWERS AND THUNDERSTORMS AND WIND SHIFT. MVFR TO IFR CONDITIONS WILL BE POSSIBLE IN SHOWER ACTIVITY. AS THE FRONT PROGRESSES...THESE SHOWERS WILL BECOME MORE WIDESPREAD...WITH GUSTY WINDS POSSIBLE AT REMAINING TERMINALS. MOUNTAIN TOPS WILL REMAIN OBSCURED IN ONGOING PRECIPITATION. MUCH OF THE SHOWER ACTIVITY DOES LOOK TO RELAX AFTER 00Z THIS EVENING...THOUGH SOME ISOLATED ACTIVITY WILL REMAIN THROUGH THE REMAINDER OF THE FORECAST PERIOD. EAST OF THE CONTINENTAL DIVIDE...KCPR/KCOD/KRIW/KWRL/KLND ROUTES TODAY REMAINS THE MAIN PERIOD OF CONCERN...AS A COLD FRONT PROGRESSES THROUGH THE AREA. SHOWERS AND THUNDERSTORMS WILL SPREAD EAST OF THE DIVIDE THIS AFTERNOON...WITH EASTERN WYOMING SEEING THE FRONTAL PASSAGE BY 04Z THIS EVENING. THOUGH SHOWER ACTIVITY WILL WEAKEN OVERNIGHT...SOME LINGERING SHOWERS WILL BE POSSIBLE. ANY TERMINALS EXPERIENCING SHOWER ACTIVITY MAY SEE MVFR TO IFR CONDITIONS IN ANY HEAVIER RAIN. THE MOUNTAIN PASSES WILL SEE THE CONVERSION TO SNOWFALL OVERNIGHT...WITH THE AVIATION PASSES BECOMING HAZARDOUS AT TIMES. MOUNTAIN TOPS WILL BE OBSCURED WITH THE FRONT PASSAGE AND LINGERING SHOWER ACTIVITY. && .FIRE WEATHER... TODAY...SEASONALLY WARM EAST OF THE DIVIDE...COOL TO COLD ACROSS THE WEST. MODERATE FIRE DANGER OVER PORTIONS EAST OF THE DIVIDE DUE TO A VERY GUSTY WEST TO SOUTHWEST WIND DEVELOPING FROM SOUTHERN LINCOLN COUNTY...NORTHEAST ACROSS NATRONA AND JOHNSON COUNTIES. RELATIVE HUMIDITY...HOWEVER... WILL ONLY BOTTOM OUT IN THE MID 20S AT BEST TODAY. ISOLATED THUNDER WILL BE A POSSIBILITY ACROSS MOST OF WYOMING TODAY...WITH A FEW STRONG THUNDERSTORMS FOUND ACROSS JOHNSON COUNTY LATER THIS AFTERNOON AND EARLY EVENING. FIRE DANGER WILL BE LOW FOR ALL LOCATIONS ON FRIDAY WITH INCREASED MOISTURE...LOW RH VALUES AND RELATIVELY BENIGN WINDS. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...BRAUN LONG TERM...AEM AVIATION...BRANHAM FIRE WEATHER...BRAUN
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 252 AM MDT THU APR 14 2016 WYZ001>020-022>030-151200- 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- 252 AM MDT THU APR 14 2016 THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT SNOW SHOWERS WEST...RAIN SHOWERS WITH A FEW EMBEDDED THUNDERSTORMS EAST. SOME STORMS COULD BE STRONG...PRODUCING SMALL HAIL AND STRONG WIND GUSTS. STRONGEST STORMS OF THE DAY ARE EXPECTED ACROSS NORTHERN JOHNSON COUNTY...WHERE NEAR SEVERE HAIL...WIND GUSTS TO 50 MPH...AND EVEN A FUNNEL CLOUD OR TWO MAY BE FOUND. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY FRIDAY...A CHANCE OF RAIN AND SNOW...BEST ACROSS THE NORTHWEST. FRIDAY NIGHT AND SATURDAY...STRONG NORTHEAST WIND COMBINED WITH SNOW SHOWERS...CAUSING SLICK CONDITIONS AND LIMITED VISIBILITY...WILL BE POSSIBLE ALONG INTERSTATE 80 FROM ROCK SPRINGS EASTWARD. ACCUMULATING SNOW AND SLICK CONDITIONS ALSO POSSIBLE ACROSS EASTERN FREMONT COUNTY AND MOST OF NATRONA COUNTY...ESPECIALLY THE CASPER AND CASPER MOUNTAIN AREA. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE URGED TO REPORT HAIL OR WIND GUSTS OVER 45 MPH. THANK YOU.
The Riverton/Lander radar (KRIW), 37 km away, was scanning. The volume nearest the first event began at 19:26 UTC.
2 thunderstorm wind. Local standard time, as filed.
An automated sensor along the North Fork of the Popo Agie River had a peak wind of 64 mph at 1225MST. This gust was followed at 1228MST by a 62 mph gust at the ASOS at Lander Hunt Field.
A calibrated anemometer at the NWS office near Riverton registered a 59 mph wind gust.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2016Every state in 2016This day in weather historyWarnings in Wyoming, April 2016
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: 619671, 632666.