A strong pressure gradient developed as a deep low pressure system approached central Wyoming. This brought widespread south to southwest high wind to much of the area east of the Continental Divide.
Every event with a place to put it; 8 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 strong pressure gradient developed as a deep low pressure system approached central Wyoming. This brought widespread south to southwest high wind to much of the area east of the Continental Divide. Wind gusts as high as 85 mph were recorded in the Green Mountains. Gusts to 79 mph along U.S. Highway 20/26 blew over a horse trailer and forced into a ditch the truck that was towing it. Several reports of wind damage were received in the Wind River Basin where gusts to 64 mph caused roof damage in Riverton and knocked down a portion of a decaying brick building in Shoshoni.
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 Mar 26, 11:00 AM MST, 5 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 1200 PM MDT MON MAR 26 2012 .SHORT TERM...MONDAY THROUGH WEDNESDAY NIGHT UPDATED TO BOTH UPGRADE ALL WATCHES TO WARNINGS AND TO START A FEW A LITTLE EARLIER. BUFFALO ALREADY GUSTING TO 51 MPH. ALSO STARTED THE DUBOIS ZONE AT 18Z WITH THE POTENTIAL STARTING A LITTLE EARLIER THAN 21Z WITH FROPA. ALSO UPDATED THE SOUTHWEST TO INDICATE RAPIDLY FALLING TEMPERATURES WITH SNOW DEVELOPING. IT'S ALREADY SNOWING IN EVANSTON AND HIGH TEMPS WILL BE MET SOON BEFORE FALLING. QUITE A BUSY WEATHER DAY THIS MORNING WITH A LOT GOING ON. ALL IS FAIRLY QUIET RIGHT NOW BUT THINGS WILL CHANGE AS LOW PRESSURE DEVELOPS AND DEEPENS OVER WYOMING TODAY AND MOVES OFF TO THE NORTHEAST INTO SOUTHEASTERN WYOMING. A COLD FRONT WILL ALSO MOVE INTO WESTERN PORTIONS OF THE CWA DURING THE MORNING HOURS AND THEN CROSS THE AREA THIS AFTERNOON AND INTO THE EARLY EVENING HOURS. ACROSS THE WESTERN MOUNTAINS...RAIN SHOWERS WILL BREAK OUT ACROSS THE AREA THIS MORNING AND THEN CHANGE TO SNOW AS SNOW LEVELS LOWER BEHIND THE COLD FRONT. THERE COULD BE A BRIEF PERIOD OF HEAVY SNOW THAT COULD BRING A FEW INCHES OF SNOW TO THE HIGHER ELEVATIONS BUT AMOUNTS SHOULD REMAIN BELOW ADVISORY LEVEL. A FEW SNOW SHOWERS COULD EVEN MAKE INTO PLACES LIKE PINEDALE OR BIG PINEY BEFORE ENDING THIS EVENING. FOR AREAS EAST OF THE DIVIDE TODAY...THE BIG STORY WILL BE WIND. AS THE LOW DEEPENS AND MOVES TO THE NORTHEAST THE PRESSURE GRADIENT WILL RAPIDLY INCREASE DURING THE MORNING HOURS. MODELS ALSO CONTINUE TO SHOW 60 KNOT WINDS IN SOME AREAS AT LATE THIS AFTERNOON AT 700 MB ACROSS CENTRAL WYOMING. SATELLITE IMAGERY SHOWS SOME CLEARING APPROACHING FROM THE WEST AND SHOULD BE HERE IN THE MORNING. AS A RESULT DAYTIME HEATING WILL INCREASE MIXING IN THE ATMOSPHERE. GFS MOS IS VERY IMPRESSIVE SHOWING WINDS OF OVER 50 KNOTS THIS AFTERNOON AT BOTH CASPER AND ROCK SPRINGS AIRPORTS. AS A RESULT WE HAVE RAISED THE HIGH WIND WATCHES TO HIGH WIND WARNINGS ACROSS MUCH OF THE AREA FROM 9 AM TO 9 PM TODAY. THE COLD FRONTAL PASSAGE LOOKS BE LARGELY DRY EAST OF THE DIVIDE BUT WE DID STILL LEAVE A SLIGHT CHANCE OF A SHOWER OR THUNDERSTORM WITH ITS PASSAGE. MAIN THREAT FROM THE STORMS IS OBVIOUSLY DOWNBURST WINDS. WITH THE STRONG WINDS...WARM TEMPERATURES AND LOW RELATIVE HUMIDITIES AHEAD OF THE FRONT WE HAVE ALSO POSTED RED FLAG WARNINGS FOR NATRONA AND JOHNSON COUNTIES INTO THE AFTERNOON. AFTER THE FRONTAL PASSAGE ANY PRECIPITATION WILL END WITH THE EXCEPTION OF SOME LIGHT SNOW SHOWERS WITH UPSLOPE FLOW ACROSS THE WESTERN MOUNTAINS. ON TUESDAY A RIDGE WILL MOVE ACROSS THE STATE AND BRING MAINLY DRY AND QUIET WEATHER WITH LESS WIND. TEMPERATURES WILL BE COOLER ALTHOUGH STILL AT ABOVE NORMAL LEVELS. A TROUGH THEN APPROACHES THE WESTERN AREAS ON WEDNESDAY WITH A CHANCE OF SHOWERS WHILE EAST OF THE DIVIDE EXPECT A WARMER DAY WITH MORE WIND AS THE PRESSURE GRADIENT TIGHTENS ONCE AGAIN. .LONG TERM...THURSDAY THROUGH MONDAY GLOBAL MODELS ARE SHOWING A MAINLY ZONAL FLOW PATTERN ACROSS THE REGION THURSDAY AND FRIDAY. THERE SHOULD BE A COUPLE SHORTWAVES IN THIS FLOW...WHICH SHOULD RESULT IN SOME PRECIPITATION...MAINLY ALONG AND WEST OF THE DIVIDE. EAST OF THE DIVIDE...MAINLY DRY CONDITIONS ARE EXPECTED WITH ABOVE AVERAGE TEMPERATURES CONTINUING. GLOBAL MODELS ARE STRUGGLING ON THE EVOLUTION OF A TROUGH PUSHING ACROSS THE WEST SATURDAY AND SUNDAY. THE 00Z GFS AND GEM ARE MUCH MORE AMPLIFIED WITH THIS TROUGH THAN THE 00Z ECMWF. THUS...THE ECMWF IS A BIT QUICKER THAN THE GFS AND MUCH QUICKER THAN THE SLOWEST GEM SOLUTION. EITHER WAY...IT APPEARS THAT SATURDAY WILL BE MAINLY DRY...WITH ABOVE AVERAGE TEMPERATURES AND BREEZY TO WINDY CONDITIONS. AFTER SATURDAY...CONFIDENCE IS EXTREMELY LOW ON HOW THIS TROUGH WILL EVOLVE. HAVE GONE WITH A BLENDED FORECAST...WITH THE MAIN IMPACT FROM THIS TROUGH AND ASSOCIATED COLD FRONT OCCURRING IN THE LATE SATURDAY NIGHT AND SUNDAY TIME FRAME. WILL KEEP LOW POPS ONGOING FOR MONDAY DUE TO THE LARGE SPREAD IN MODEL SOLUTIONS FOR THIS UPCOMING TROUGH. IF THE 00Z OPERATIONAL GFS COMES TO FRUITION THAN THAN THE LOWER ELEVATIONS EAST OF THE DIVIDE COULD SEE SOME SNOW SUNDAY NIGHT/MONDAY...AS THE TROUGH BECOMES CUT OFF ACROSS THE FOUR CORNERS AREA WITH UPSLOPE DEVELOPING. ELEVATED FIRE WEATHER BEHAVIOR WILL BE OBSERVED AT TIMES ACROSS THE LOWER ELEVATIONS SOUTH AND EAST OF THE DIVIDE THROUGH SATURDAY DUE TO CONTINUED ABOVE AVERAGE TEMPERATURES...RELATIVELY LOW RH AND CRITICALLY DRY FUELS. HOWEVER...THE MOST EXTREME FIRE BEHAVIOR IN THE EXTENDED SHOULD OCCUR ON SATURDAY AHEAD OF THE TROUGH. WELL ABOVE AVERAGE TEMPERATURES ARE EXPECTED THURSDAY THROUGH SATURDAY WITH THE WARMEST DAY EXPECTED TO OCCUR ON SATURDAY. RECORD HIGHS COULD BE IN JEOPARDY ONCE AGAIN ON SATURDAY. IN WAKE OF THE COLD FRONT DURING THE WEEKEND...BELOW AVERAGE TEMPERATURES WILL BE POSSIBLE SUNDAY AND/OR MONDAY. .AVIATION.../18Z ISSUANCE/ A STORM SYSTEM WILL MOVE ACROSS WY TODAY AND INTO EASTERN MONTANA THIS EVENING. STRONG SOUTH WINDS WILL BLOW AHEAD OF THE FRONT AND STRONG WEST WINDS BEHIND A COLD FRONT TODAY AS IT MOVES FROM WEST TO EAST ACROSS THE STATE. RAIN SHOWERS WILL RAPIDLY TURN TO SNOW SHOWERS FROM WEST TO EAST ACROSS WESTERN WYOMING AS WELL AS SWEETWATER COUNTY ALONG WITH AREAS OF MVFR CONDITIONS AND LOCAL IFR CONDITIONS. ISOLATED THUNDERSTORMS MAY OCCUR IN THE WEST UNTIL 20Z. THE PRECIPITATION WILL LINGER IN THE WEST THROUGH 00Z TUESDAY...THEN DECREASE. EAST OF THE DIVIDE...ISOLATED SHOWERS AND THUNDERSTORMS WILL OCCUR AFTER 18Z ALONG AND AHEAD OF THE COLD FRONT AS IT SWINGS EAST ACROSS CENTRAL WY. LOCAL MVFR CONDITIONS WILL BE POSSIBLE. THE SHOWER ACTIVITY WILL END AFTER 00Z. EXPECT SOME MOUNTAIN WAVE ACTION...TURBULENCE...AND MOUNTAIN OBSCURATION MONDAY INTO MONDAY NIGHT DUE TO THIS STORM SYSTEM. LOOK FOR RAPIDLY CHANGING WEATHER CONDITIONS ACROSS THE REGION. AFTER 06Z VFR CONDITIONS WILL OCCUR WITH WINDY AREAS AND ISOLATED SNOW SHOWERS IN THE NORTHWEST WY MOUNTAINS. .FIRE WEATHER... CRITICAL FIRE WEATHER CONDITIONS WILL CONTINUE ACROSS MUCH OF THE AREA EAST OF THE DIVIDE INTO MONDAY AHEAD OF A STRONG STORM SYSTEM AND COLD FRONT...MAINLY NATRONA AND JOHNSON COUNTIES WHERE RED FLAG WARNINGS HAVE BEEN ISSUED. PLEASE SEE THE FIRE WEATHER PRODUCTS FOR DETAILS. THIS COLD FRONT IS EXPECTED TO ARRIVE IN THE RED DESERT MONDAY MORNING...MOVE EAST AND NORTHEAST INTO CENTRAL WYOMING IN THE AFTERNOON AND INTO THE NORTHEASTERN PART OF THE DISTRICT BY LATE AFTERNOON. A VERY DRY ATMOSPHERE WITH RH'S OF 10 TO 15 PERCENT AND VERY STRONG IF NOT HIGH WINDS ARE EXPECTED AHEAD OF THIS FRONT ALONG WITH THE POTENTIAL FOR ISOLATED DRY LIGHTNING. BEHIND THE FRONT...WINDS WILL SHIFT FROM A SOUTHERLY DIRECTION TO MORE OF A WEST TO SOUTHWEST DIRECTION AND CONTINUE VERY STRONG WITH AN INCREASE IN RELATIVE HUMIDITIES. STRONG WINDS WILL CONTINUE MONDAY NIGHT AND MAY BE VERY STRONG IN JOHNSON AND PARK COUNTIES AND THE UPPER WIND RIVER BASIN FOOTHILLS. LESS WIND AND HIGHER RH'S ARE EXPECTED ON TUESDAY ALONG WITH TEMPERATURES THAT WILL BE 10 TO 15 COOLER THAN MONDAY. FIRE DANGER MAY ELEVATE AGAIN EAST OF THE DIVIDE ON WEDNESDAY AS TEMPERATURES WARM AND WINDS INCREASE ONCE AGAIN AS A TROUGH APPROACHES FROM THE WEST. && .RIW WATCHES/WARNINGS/ADVISORIES... HIGH WIND WARNING UNTIL 9 PM MDT THIS EVENING WYZ015-017>020-030. HIGH WIND WARNING UNTIL 6 AM MDT TUESDAY WYZ009>011. RED FLAG WARNING UNTIL 6 PM MDT THIS EVENING WYZ281-285. HIGH WIND WARNING UNTIL 6 AM MDT TUESDAY WYZ016. HIGH WIND WARNING FROM 3 PM THIS AFTERNOON TO 6 AM MDT TUESDAY WYZ002-003. RED FLAG WARNING UNTIL 3 PM MDT THIS AFTERNOON WYZ280-300. && UPDATE...SKRBAC SHORT TERM...HATTINGS LONG TERM...WM AVIATION...LIPSON FIRE WEATHER...HATTINGS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 1048 AM MDT MON MAR 26 2012 WYZ001>020-022>030-271100- 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- 1048 AM MDT MON MAR 26 2012 ...RED FLAG WARNINGS IN EFFECT TODAY FOR THE LOWER ELEVATIONS OF JOHNSON AND NATRONA COUNTIES... ...NUMEROUS HIGH WIND WARNINGS FOR AREAS EAST OF THE DIVIDE AS WELL AS SWEETWATER COUNTY TODAY AND TONIGHT... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT CRITICAL FIRE WEATHER BEHAVIOR FOR JOHNSON COUNTY...THE LOWER ELEVATIONS OF THE SOUTHERN BIG HORN MOUNTAINS AND NATRONA COUNTY TODAY. SEE FIRE WEATHER PRODUCTS FOR DETAILS. ALSO VERY STRONG WINDS WILL OCCUR TODAY ACROSS MUCH OF CENTRAL AND SOUTHERN WYOMING. SEE THE HIGH WIND WARNING STATEMENTS FOR MORE DETAILS. ALSO ISOLATED THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON. THE MAIN HAZARD FROM THESE THUNDERSTORMS WILL BE THE LOCAL ENHANCEMENT OF THE ALREADY VERY STRONG WINDS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY WEDNESDAY THROUGH SATURDAY...ELEVATED TO EXTREME FIRE WEATHER BEHAVIOR POSSIBLE AT TIMES ACROSS THE LOWER ELEVATIONS EAST OF THE DIVIDE...AS WELL AS SWEETWATER COUNTY. THE MOST EXTREME FIRE WEATHER BEHAVIOR IS EXPECTED ON SATURDAY. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE URGED TO REPORT ANY WIND GUSTS OVER 50 MPH OR ANY DAMAGE CAUSED BY THE VERY STRONG WINDS. THANK YOU. TEAM RIVERTON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 1130 AM MDT MON MAR 26 2012 WYZ028>030-262100- EAST SWEETWATER COUNTY-FLAMING GORGE-ROCK SPRINGS AND GREEN RIVER- 1130 AM MDT MON MAR 26 2012 A STRONG COLD FRONT WILL BLAST THROUGH SWEETWATER COUNTY FROM WEST TO EAST THROUGH MID AFTERNOON TODAY. STRONG SOUTH WINDS OF 30 TO 40 MPH WITH GUSTS TO 50 MPH ALONG WITH HIGHER WIND GUSTS OF 60 MPH IN THE EASTERN PORTION OF THE COUNTY WILL BE REPLACED BY STRONG WEST WINDS OF 25 TO 35 MPH WITH GUSTS TO 50 MPH WHICH WILL USHER IN SHARPLY COLDER TEMPERATURES FROM THE WEST. RAIN SHOWERS ASSOCIATED WITH THE COLD FRONT WILL CHANGE RAPIDLY TO SNOW WHICH WHICH WILL ACCUMULATE AROUND AN INCH BY MID AFTERNOON ALONG WITH LOCAL ACCUMULATIONS OF 2 INCHES. A RUMBLE OF THUNDER OR TWO IS ALSO POSSIBLE. BECAUSE OF THE RAPIDLY COOLING ROAD SURFACES... ANY SLUSH FROM THE BRIEF HEAVY SNOW SHOWERS THAT FALL THIS AFTERNOON WILL TURN TO ICE. WITH ADDITIONAL SNOW FALLING ON THE ICE...VERY SLIPPERY ROAD CONDITIONS ARE EXPECTED ON AREA HIGHWAYS INCLUDING INTERSTATE 80 ACROSS SWEETWATER COUNTY THIS AFTERNOON. IN ADDITION TO THE SLIPPERY ROAD CONDITIONS...THE VISIBILITY WILL BE REDUCED TO BELOW ONE QUARTER OF A MILE AT TIMES DURING THE HEAVIER SNOW SQUALLS EXPECTED. IF TRAVELING THROUGHOUT SWEETWATER COUNTY THIS AFTERNOON... ANTICIPATE DANGEROUS CROSS WINDS AS WELL AS A RAPID RETURN TO WINTER DRIVING CONDITIONS. LIPSON
The national radar mosaic for the moment the first event began.
8 high wind. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2012Every state in 2012This day in weather historyWarnings in Wyoming, March 2012
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: 362930, 362928, 362927, 362925, 362929, 362921, 362923, 362920.