Strong southwest flow ahead of an approaching cold front brought high winds to portions of central Wyoming. The strongest winds were recorded in western Natrona County.
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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.
Strong southwest flow ahead of an approaching cold front brought high winds to portions of central Wyoming. The strongest winds were recorded in western Natrona County. In that region, sustained winds of 40 mph or more and gusts to 63 mph were measured during the late morning and early afternoon.
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 Nov 21, 3:34 AM MST, 5 hours 56 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 334 AM MST WED NOV 21 2012 .SHORT TERM...TODAY THROUGH FRIDAY NIGHT STRONG SOUTHWEST FLOW AHEAD OF AN APPROACHING TROUGH WILL LEAD TO AREAS OF STRONG WIND TODAY AND TONIGHT...ESPECIALLY ACROSS SOUTHEAST FREMONT COUNTY AND IN NATRONA COUNTY AS SOUTHWEST WINDS INCREASE TO 30 TO 40 MPH WITH GUSTS AROUND 60 MPH THIS AFTERNOON AND EVENING...THE HIGHEST WINDS IN NATRONA COUNTY ARE EXPECTED TO REMAIN OUTSIDE OF THE POPULATED AREAS BUT WITH INCREASED TRAVEL NEAR THE THANKSGIVING HOLIDAY...IT WAS DECIDED TO ERROR ON THE SIDE OF CAUTION. WINDS WILL ALSO INCREASE ACROSS THE HIGHER ELEVATIONS WITH 60-70 MPH WIND GUSTS BECOMING FREQUENT IN ALL MOUNTAIN RANGES AS AN UPPER LEVEL JET SAGS INTO THE REGION AND LEE SIDE TROUGHING STRENGTHENS THE SURFACE GRADIENT. THE APPROACHING JET STREAK WILL ALSO ENHANCE PRECIPITATION ACROSS THE NORTHWEST TODAY AND TONIGHT AS ISENTROPIC UPGLIDE PERSISTS IN AN EVER INCREASING SUPPLY OF PACIFIC MOISTURE. A COLD FRONT ASSOCIATED WITH THE UPPER LEVEL TROUGH WILL ARRIVE IN THE WEST THIS EVENING...LOWERING SNOW LEVELS AND PROVIDING AN ADDED SOURCE OF LIFT. HAVE ISSUED WINTER WEATHER ADVISORIES FOR THE FAR NORTHWESTERN HIGH ELEVATION ZONES FOR MODERATE SNOW AND STRONG WINDS CAUSING BLOWING SNOW AND DIFFICULT TRAVEL ACROSS TOGWOTEE AND TETON PASS OVERNIGHT...AS WELL AS THROUGHOUT THE PARK. PERIODS OF MODERATE SNOW WILL ALSO MOVE INTO THE ABSAROKAS AND COMBINE WITH STRONG WIND...BUT THE VERY WARM SOUTHWEST FLOW WILL LIKELY PREVENT MUCH ACCUMULATION AS YOU MOVE FURTHER EAST...AND SOUTH INTO THE WYOMING AND SALTS. THE HIGH WIND WATCH WAS LEFT ALONE FOR THE UPPER WIND RIVER BASIN...INCLUDING DUBOIS. THE POTENTIAL FOR VERY STRONG POST FRONTAL WINDS THROUGH THE DUBOIS AREA AS 100KT WINDS AT 500MB ALIGN PERFECTLY WITH THE BASIN...HOWEVER THE SURFACE GRADIENT REMAINS ORIENTED A LITTLE TOO WESTERLY...SO THE HIGH WIND WATCH REMAINS FOR TONIGHT. ELSEWHERE...MOST AREAS WILL BE WINDY WITH FROPA AND IN THE HOURS AHEAD OF AND IMMEDIATELY BEHIND...GENERALLY JUST KEEPING GUSTS IN THE 40-50 MPH RANGE FOR NOW IN UNWARNED AREAS THAT FAVOR SOUTHWEST TO WESTERLY FLOW...A VERY WINDY DAY BUT PERHAPS NOT WORTHY OF A HIGH WIND WARNING. ANOTHER POTENTIAL TRAVEL ISSUE WILL BE IN NORTHERN JOHNSON COUNTY ON THURSDAY ALONG AS THE CANADIAN FRONT MOVES IN FROM THE NORTH...WITH A QUICK BLAST OF SNOW AND A PERIOD OF STRONG NORTHWESTERLY WINDS COMING AROUND THE BIGHORNS. CLEARING AND COLD THURSDAY NIGHT WITH WARM ADVECTION MOVING IN ALOFT. LITTLE BIT OF FRESH SNOW AND THIS DEVELOPING INVERSION AND SUBSIDING WINDS MAY RESULT IN SOME MORE FOG IN THE WESTERN VALLEYS/BASINS. FRIDAY WILL BE DRY WITH WARMING TEMPERATURES... ESPECIALLY MOUNTAINS...FOOTHILLS AND BREEZY AREAS AS THE LEE TROUGH REDEVELOPS AND TURNS WINDS BACK ON IN THE ROCK SPRINGS TO CASPER CORRIDOR...THOUGH THEY WILL BE LESS EXTREME THAN WHAT WILL BE EXPERIENCED TODAY AND TONIGHT. .LONG TERM...SATURDAY THROUGH WEDNESDAY MEDIUM RANGE MODELS BEGIN THE PERIOD IN GOOD AGREEMENT WITH LARGE-SCALE FEATURES ON SATURDAY SHOWING...FROM WEST TO EAST...AN UPPER HIGH OVER THE BERING STRAIT WITH A TROUGH UNDERNEATH ACROSS THE ALEUTIAN CHAIN...AMPLIFYING RIDGE ACROSS THE EASTERN PACIFIC WITH GULF OF ALASKA LOW OPENING UP AND SLIDING DOWN FRONT SIDE OF RIDGE ALONG THE BRITISH COLUMBIA COAST. DRY AND MILD WESTERLY FLOW PREVAILS OVER WYOMING EARLY SATURDAY WITH COLD FRONT AND PACIFIC MOISTURE FETCH SAGGING SOUTH ACROSS NORTHERN WYOMING DURING THE DAY. THIS WILL BRING INCREASING SNOW TO THE NW MOUNTAINS WITH POSSIBLY A RAIN SNOW MIX IN JACKSON HOLE DURING THE AFTERNOON. UPPER TROUGH CONTINUES TO DIG SE ACROSS THE INTERMOUNTAIN WEST SATURDAY NIGHT INTO THE NORTHERN GREAT BASIN LATE SUNDAY. AT THE SURFACE...ARCTIC FRONT DOES NOT BLAST ACROSS THE AREA ON SUNDAY AS IN 20/00Z RUNS...BUT PUSHES TO VICINITY CASPER-RIVERTON LINE BY 00Z MONDAY WITH THE SURFACE LOW OVER SOUTH CENTRAL WYOMING. THIS WILL MAKE PRECIPITATION TYPE MORE TRICKY WITH PRECIPITATION STARTING OUT AS A MIX OF RAIN/SNOW ACROSS THE NORTHERN BASINS SATURDAY NIGHT AND SUNDAY...CHANGING TO SNOW THROUGH THE DAY SUNDAY. BREEZY/WINDY AND TEMPERATURES IN THE 40S TO PREVAIL SOUTH OF THE FRONT SUNDAY WITH INCREASING SHOWERS AND EVEN A FEW THUNDERSTORMS...AND A MIXTURE OF PRECIPITATION ALONG THE FRONTAL BOUNDARY WITH POSSIBLY BRIEF FREEZING RAIN. STRONG LEE- CYCLOGENESIS OVER EASTERN COLORADO BY SUNDAY NIGHT WILL DRAG THE FRONT SOUTH ACROSS THE AREA WITH A CHANGE TO ALL SNOW...TEMPERATURES FALLING INTO THE TEENS TO LOWER 20S. MODEL SPREAD INCREASES MONDAY THROUGH WEDNESDAY WITH GFS REINFORCING COLD UPPER TROUGH WITH A CLIPPER DIVING SOUTH INTO THE NORTHERN ROCKIES ON MONDAY. ECMWF IS QUICKER TO DISLODGE UPPER LOW OVER THE ALEUTIANS...DEVELOPING A DRIER WESTERLY FLOW ACROSS WYOMING ON MONDAY. FORECAST PREFERS SLOWER PROGRESSION OF UPPER TROUGH THOUGH CONFIDENCE IS LOW IN THE DETAILS. FORECAST KEEPS CHANCES FOR LIGHT FLUFFY SNOW ACROSS THE AREA MONDAY IN THE HEART OF COLD TROUGH WITH A GRADUAL TAPERING OFF OF SNOW AND SLIGHT MODERATION OF TEMPERATURES TUESDAY. FORECAST LEANS TOWARD GEFS MEAN ON WEDNESDAY WITH WESTERLY FLOW...TEMPERATURES RECOVERING TO NEAR SEASONAL NORMALS AND CHANCES OF SNOW IN THE WEST. && .AVIATION.../12Z ISSUANCE/ EAST OF THE DIVIDE...VFR CONDITIONS...BUT WINDY IN SPOTS ARE EXPECTED AHEAD OF AN APPROACHING TROUGH TODAY. STRONG SOUTHWEST WINDS ARE EXPECTED IN TYPICAL AREAS...SUCH AS AT THE KCPR TERMINAL...AND ALONG EASTERN SLOPES OF MOUNTAIN RANGES TODAY. THIS WILL RESULT IN AREAS OF TURBULENCE AS WELL AS SOME LOW LEVEL SHEAR TODAY ESPECIALLY ON THE LEE SIDE OF MOUNTAIN RANGES. AFTER 00Z...A STRONG COLD FRONT WILL PUSH EAST AND SOUTH...BRINGING A WIND SHIFT AND WINDY NORTHWEST WIND...MAINLY ACROSS THE WIND RIVER BASIN AND NORTHERN JOHNSON COUNTY. SOME SHOWER ACTIVITY IS EXPECTED TO SPILL EAST OF THE DIVIDE TONIGHT...WITH MUCH OF THE IMPACT ACROSS THE BIGHORN MTS...WHERE IFR/MVFR CONDITIONS ARE LIKELY. SOME LOW CLOUDS COULD OCCUR IN WAKE OF THE COLD FRONT...BUT CONFIDENCE IS NOT HIGH ENOUGH TO INSERT THEM AT AREA TERMINALS AT THE MOMENT. ALONG AND WEST OF THE DIVIDE...PRECIPITATION WILL BECOME WIDESPREAD ACROSS NORTHWEST WYOMING THIS MORNING...RESULTING IN MOUNTAIN OBSCURATIONS IN IFR CONDITIONS. AS THE STORM SYSTEM BEGINS TO PULL ACROSS THE REGION...PRECIPITATION/LOW CLOUDS WILL EXPAND FARTHER SOUTH IN THE AFTERNOON...WITH THE HEAVIEST PRECIPITATION OCCURRING PROBABLY BETWEEN 21Z WEDNESDAY AND 03Z THURSDAY AS THE FRONTAL ZONE PUSHES ACROSS WESTERN WYOMING. SNOW LEVELS WILL BE RELATIVELY HIGH INITIALLY WITH ALL RAIN IN THE VALLEYS...BUT SNOW LEVELS SHOULD DROP TO VALLEY FLOORS BY AROUND 00Z THURSDAY. KJAC WILL BE MOST IMPACTED WITH THIS SYSTEM WITH PERIODS OF MVFR/IFR CONDITIONS THIS AFTERNOON AND EVENING...WITH LESS IMPACTS FARTHER SOUTH WITH THE LEAST IMPACT AT KRKS. IMPROVING CONDITIONS ARE EXPECTED AFTER 06Z THURSDAY AS THE SYSTEM PULLS AWAY...BUT SOME MOUNTAIN OBSCURATIONS WILL REMAIN. TURBULENCE AND ICING CONCERNS WILL INCREASE TODAY...AND PLEASE SEE THE LATEST STATEMENTS ISSUED BY THE AVIATION WEATHER CENTER FOR THE MOST UP TO DATE INFORMATION ON THESE TOPICS. && .FIRE WEATHER... WINDY TO VERY WINDY ACROSS MOST OF THE MOUNTAINS THROUGH THURSDAY MORNING AND ALSO ALONG THE WIND CORRIDOR FROM JEFFREY CITY TO CASPER. A STORM SYSTEM WILL MOVE IN QUICKLY THIS MORNING WITH SNOW DEVELOPING IN THE NORTHWEST MOUNTAINS AND THEN GRADUALLY SPREADING SOUTH LATE IN THE DAY INTO THE EVENING. A STRONG COLD FRONT WILL PUSH INTO THE WEST LATE IN THE AFTERNOON AND SWING EAST OF THE DIVIDE IN THE EVENING. AFTER ANOTHER MILD DAY EAST OF THE DIVIDE TODAY...IT WILL COOL SHARPLY ON THURSDAY BY ABOUT 20 DEGREES IN MOST AREAS. && .RIW WATCHES/WARNINGS/ADVISORIES... HIGH WIND WARNING FROM 8 AM THIS MORNING TO 2 AM MST THURSDAY WYZ019-020. HIGH WIND WATCH FROM THIS EVENING THROUGH THURSDAY MORNING WYZ016. WINTER WEATHER ADVISORY FROM 11 AM THIS MORNING TO 2 AM MST THURSDAY WYZ001-012. && SHORT TERM...ALLEN LONG TERM...AEM AVIATION...WM FIRE WEATHER...ALLEN
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 500 AM MST WED NOV 21 2012 WYZ001>020-022>030-221200- 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 MST WED NOV 21 2012 ...HIGH WIND WARNING FOR NATRONA COUNTY AND SOUTHEAST FREMONT COUNTY 8 AM THIS MORNING UNTIL 2 AM THURSDAY... ...WINTER WEATHER ADVISORY FOR PORTIONS OF NORTHWEST WYOMING FROM 11 AM THIS MORNING UNTIL 2 AM THURSDAY... ...HIGH WIND WATCH FOR UPPER WIND RIVER BASIN TONIGHT THROUGH EARLY THURSDAY MORNING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT STRONG WINDS EXPECTED IN SOUTHEAST FREMONT COUNTY AND NATRONA COUNTY TODAY...WINDS WILL ALSO BE STRONG OVER THE HIGHER ELEVATIONS ACROSS THE STATE WITH GUSTS OVER 60 MPH COMMON. SNOW INCREASING ACROSS THE NORTHWEST TODAY AND TONIGHT WILL INTERACT WITH THESE WINDS CREATING DIFFICULT TRAVEL OVER TETON PASS...TOGWOTEE PASS...AND THROUGHOUT YELLOWSTONE NATIONAL PARK. VERY STRONG WINDS ALSO POSSIBLE BETWEEN CROWHEART AND DUBOIS TONIGHT. A COLD FRONT MOVING THROUGH TONIGHT WILL DROP TEMPERATURES ACROSS THE STATE...CREATING WIND CHILL AS LOW AS TEN BELOW IN THE WESTERN MOUNTAINS. .DAYS TWO THROUGH SEVEN...THANKSGIVING DAY THROUGH TUESDAY THANKSGIVING MORNING...STRONG WINDS AND PERIODS OF SNOW MAY CAUSE DIFFICULT TRAVEL NEAR BUFFALO. STRONG WINDS...COLD TEMPERATURES AND LIGHT SNOW WILL CONTINUE IN THE ABSAROKAS AND NORTHERN BIGHORNS. SNOW AND WIND WILL TAPER OFF BY NOON. SATURDAY NIGHT AND SUNDAY...SNOW WILL INCREASE ACROSS THE WEST SATURDAY NIGHT AND CONTINUE THROUGH SUNDAY. A CANADIAN COLD FRONT WILL SPREAD RAIN AND SNOW ACROSS NORTH AND CENTRAL WYOMING SUNDAY WITH BRIEF PERIODS OF FREEZING RAIN POSSIBLE. ROADS WILL LIKELY BECOME ICY AND SNOW-COVERED THROUGH THE DAY SUNDAY ACROSS NORTH AND CENTRAL WYOMING...MAKING TRAVEL HAZARDOUS. SUNDAY NIGHT AND MONDAY...MUCH COLDER WITH AREAS OF LIGHT SNOW. EXPECT ICY AND SNOW-COVERED ROADS. .SPOTTER INFORMATION STATEMENT... PLEASE REPORT ANY WIND GUSTS OF 50 MPH OR HIGHER...OR ANY WIND DAMAGE. THANK YOU. TEAM RIVERTON
The national radar mosaic for the moment the first event began.
2 high wind. Local standard time, as filed.
The Wyoming Department of Transportation wind sensor measured 40 mph to 42 mph sustained winds intermittently at Hiland.
Fales Rock RAWS reported numerous wind gusts of over 58 mph including a peak wind gust of 63 mph on November 21.
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, November 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: 416231, 416230.