A tight pressure gradient across the area allowed strong southwest wind to develop along the Green Mountains northeast through Natrona County. Gusts to 64 mph were recorded for several hours in the mountains and sustained wind over 40 mph was measured along Interstate 25 north of Casper.
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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.
A tight pressure gradient across the area allowed strong southwest wind to develop along the Green Mountains northeast through Natrona County. Gusts to 64 mph were recorded for several hours in the mountains and sustained wind over 40 mph was measured along Interstate 25 north of Casper.
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 27, 10:15 AM MST, 35 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 1115 AM MDT SUN MAY 27 2012 .SHORT TERM...TODAY THROUGH TUESDAY NIGHT AFTER A WET FEW DAYS OVER MOST OF THE CWA...SHOWERS ARE ENDING EAST OF THE CONTINENTAL DIVIDE AS A DRY SLOT MOVES IN FROM THE SOUTH. THE MAIN UPPER LOW IS OVER NORTHERN UTAH THIS MORNING. AREAS OF FOG ARE POSSIBLE INTO MID MORNING EAST OF THE DIVIDE DUE TO THE HIGH AMOUNTS OF RESIDUAL LL MOISTURE. SNOW SHOWERS WILL INCREASE ACROSS THE WESTERN MOUNTAINS TODAY SO HAVE LEFT WINTER WEATHER ADVISORY IN EFFECT THROUGH THIS AFTERNOON. THE UPPER LOW WILL MIGRATE NORTH AND EAST TODAY PUSHING A COLD FRONT THROUGH THE AREA. ALTHOUGH A COLD FRONT WILL MOVE THROUGH...WARMER TEMPERATURES ARE EXPECTED EAST OF THE DIVIDE AS THE FRONT SCOURS OUT THE INVERSIONS THAT HAVE BEEN IN PLACE THE LAST FEW DAYS. MARGINAL INSTABILITY AND FRONTAL FORCING WILL BRING A CHANCE FOR ISOLATED SHOWERS AND THUNDERSTORMS OVER THE CENTRAL BASINS. WIND WILL INCREASE ACROSS THE SOUTHERN WIND CORRIDOR FROM ROCK SPRINGS TO CASPER AS LL FLOW VEERS FROM SOUTH TO SOUTHWEST. A HIGH WIND WARNING HAS BEEN ISSUED FOR THE GREEN MOUNTAINS AND RATTLESNAKE HILLS AS WELL AS THE LOWER ELEVATIONS OF NATRONA COUNTY. COOL CONDITIONS WILL CONTINUE THROUGH THE MEMORIAL DAY HOLIDAY WITH MOUNTAIN SHOWERS AND DRIER CONDITIONS IN THE BASINS. WARM ADVECTION WITH A WEAK AND MOSTLY FLAT RIDGE WILL BRING TEMPERATURES UP ABOUT TEN DEGREES FOR TUESDAY BUT A SHORTWAVE TROUGH WILL BRING SOME SHOWER ACTIVITY TO THE NORTH WITH THE GREATEST COVERAGE OVER THE MOUNTAINS. THE SHOWERS WILL DECREASE OVERNIGHT INTO WEDNESDAY MORNING. .LONG TERM...WEDNESDAY THROUGH SUNDAY RIDGE BUILDS INTO THE WESTERN U.S TO START THE MEDIUM RANGE PERIOD LEAVING OUR AREA IN NW FLOW AND SUSCEPTIBLE TO A COUPLE OF SEWD MOVING CLIPPER TYPE SYSTEMS. TIMING AND STRENGTH VARY BETWEEN THE GFS AND ECMWF BUT THE GENERAL CONSENSUS POINTS TO A CHANCE OF SHOWERS AND SOME LATE DAY THUNDERSTORMS ACROSS THE NORTHERN MOUNTAINS WITH AT LEAST ISOLATED IF NOT SCATTERED SHOWERS DURING SHORTWAVE PASSAGE ACROSS THE LOWER ELEVATIONS OF THE NORTH AND EAST WED AND THU. RIDGE THEN MOVES CLOSER AND EVENTUALLY OVERHEAD ON SATURDAY FOR WARMER AND DRIER WEATHER. HOWEVER...IN THE WEST BY SATURDAY...A STRONGER UPPER LEVEL TROUGH OVER THE PACNW WILL BEGIN TO IMPACT AT LEAST THE NWRN ZONES WITH AN INCREASING CHANCE OF SHOWERS AND THUNDERSTORMS. THE MODELS ARE KEEPING MOST OF THE ENERGY FROM OUR FAR NRN ZONES UP INTO MONTANA ATTM BUT WE'LL HAVE TO WATCH THIS OVER THE NEXT FEW DAYS. WILL PUT IN A SLIGHT CHANCE ACROSS THE ERN ZONES FOR SUNDAY WITH POTENTIAL FROPA. OTHERWISE...THE MAIN EFFECT FOR AT LEAST THE SRN HALF WILL BE WINDY CONDITIONS OVER THE WEEKEND. TEMPERATURES WILL PEAK SATURDAY AND THEN BEGIN COOLING FROM WEST TO EAST ON SUNDAY. && .AVIATION.../18Z ISSUANCE/ AN UPPER LOW PRESSURE SYSTEM WILL LIFT NORTH ACROSS MONTANA TODAY. WRAPAROUND PRECIPITATION WITH WIDESPREAD MVFR CONDITIONS IN -SN AND MOUNTAIN OBSCURATIONS ACROSS THE WESTERN MOUNTAINS...AREAS OF IFR/LIFR CONDITIONS IN SN WILL PREVAIL...ESPECIALLY AROUND KJAC. BRIEF IFR IS POSSIBLE AT KPNA AND KBPI WITH SNOW SHOWERS. WITH GRADUAL IMPROVEMENT OF CONDITIONS FROM THE SOUTH AND WEST SUNDAY NIGHT. EAST OF THE DIVIDE AND SWEETWATER COUNTY...WEST SOUTHWEST WINDS WILL INCREASE TO 20-35 KTS ACROSS SOUTH AND CENTRAL WYOMING WITH THE STRONGEST WINDS GUSTING NEAR 50KTS ALONG A LINE VCNTY KCPR TO 90NM SOUTHWEST. AFTER BRIEFLY LIFTING NORTHWARD...A COLD FRONT WILL PUSH SOUTH ACROSS NORTHERN WYOMING DURING THE AFTERNOON WITH AREAS OF MVFR/LOCAL IFR RAIN AND SNOW BEHIND THE FRONT. CONDITIONS WILL GRADUALLY IMPROVE IN THE NORTH SUNDAY NIGHT WHILE WINDS GRADUALLY DIMINISH ACROSS SOUTHERN AND CENTRAL WYOMING. SHOWERS WILL BE IN THE VICINITY OF MOST TAF SITES THIS AFTERNOON AND EARLY EVENING. && .FIRE WEATHER... HIGH HUMIDITY AND LINGERING SHOWER ACTIVITY WILL KEEP FIRE WEATHER CONCERNS LOW FOR MOST OF THE AREA. DRIER CONDITIONS ARE EXPECTED OVER SWEETWATER COUNTY WITH WINDY CONDITIONS DEVELOPING TODAY. HIGH WIND IS POSSIBLE OVER THE GREEN MOUNTAINS THROUGH CASPER TODAY BUT HUMIDITY WILL BE VERY HIGH IN THOSE AREAS. && .RIW WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING WYZ001-002-012. HIGH WIND WARNING FROM 9 AM THIS MORNING TO 9 PM MDT THIS EVENING WYZ019-020. && SHORT TERM...BERC LONG TERM...SKRBAC AVIATION...HATTINGS FIRE WEATHER...BERC
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 334 AM MDT SUN MAY 27 2012 WYZ001>020-022>030-281200- 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- 334 AM MDT SUN MAY 27 2012 ...WINTER WEATHER ADVISORY FOR THE NORTHWEST MOUNTAINS REMAINS IN EFFECT THROUGH THIS AFTERNOON... ...HIGH WIND WARNING IS IN EFFECT FOR NATRONA COUNTY AND THE GREEN MOUNTAINS THROUGH THIS EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT SIGNIFICANT SNOW IS EXPECTED ACROSS THE MOUNTAINS OF NORTHWEST WYOMING THROUGH THIS AFTERNOON. PLEASE SEE WINTER WEATHER ADVISORY PRODUCT FOR MORE INFORMATION. STRONG WIND WILL DEVELOP ACROSS SOUTHERN WYOMING WITH THE STRONGEST WIND AFFECTING THE GREEN MOUNTAINS AND RATTLESNAKE HILLS. AND PORTIONS OF NATRONA COUNTY. PLEASE SEE HIGH WIND WARNING PRODUCT FOR MORE INFORMATION. .DAYS TWO THROUGH SEVEN...MEMORIAL DAY THROUGH SATURDAY MEMORIAL DAY THROUGH THURSDAY...ISOLATED THUNDERSTORMS ARE POSSIBLE ACROSS NORTHERN WYOMING. SATURDAY...A COLD FRONT WILL MOVE INTO NORTHWEST WYOMING LEADING TO AN INCREASING CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ENCOURAGED TO REPORT SNOWFALL ACCUMULATION...STRONG WIND GUSTS OR ANY WIND DAMAGE. THANK YOU. TEAM RIVERTON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 606 AM MDT SUN MAY 27 2012 WYZ010-271400- NORTHEAST JOHNSON COUNTY- 606 AM MDT SUN MAY 27 2012 AREAS OF FOG WILL CONTINUE IN PARTS OF NORTHERN JOHNSON COUNTY THIS MORNING. VISIBILITY WILL BE REDUCED TO UNDER ONE MILE...WITH SOME PLACES SEEING VISIBILITY AS LOW AS ONE QUARTER MILE. MOTORISTS SHOULD BE PREPARED FOR RAPIDLY CHANGING CONDITIONS DUE TO THE FOG... ESPECIALLY ALONG INTERSTATE 90. THE FOG IS EXPECTED TO LIFT AND GRADUALLY DISSIPATE BY 9 AM. SKRBAC
The national radar mosaic for the moment the first event began.
2 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, May 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: 380570, 380573.