Strong winds aloft combined with a passing upper level disturbance and tight surface pressure gradient generated gusty winds over portions of southeast Wyoming.
Every event with a place to put it; 7 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 CYS wrote it up.
Strong winds aloft combined with a passing upper level disturbance and tight surface pressure gradient generated gusty winds over portions of southeast Wyoming.
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 Cheyenne, WY wrote its last area forecast discussion before the first event at Dec 25, 11:54 PM MST, 3 hours 31 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHEYENNE WY 1154 PM MST SUN DEC 25 2011 .AVIATION...06Z TAFS VFR CONDITIONS EXPECTED NEXT 24 HOURS. WINDS WILL BE ON THE INCREASE THROUGH THE NEXT 24 HOURS AND WILL LIKELY CONTINUE THROUGH THE WEEK. CLAYCOMB && PREV DISCUSSION... /ISSUED / SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT...WATER VAPOR IMAGERY SHOWS SHORTWAVE TROUGH ENTERING THE PAC NW TODAY WITH OROGRAPHIC CIRRUS SPILLING OVER THE CANADIAN ROCKIES AND DOWNWARD INTO THE NORTHERN PLAINS. STARTING TO SEE SOME GOOD SFC PRESSURE FALLS ACROSS THE REGION...WITH 4 TO 5 MB/HR ACROSS THE EASTERN HALF OF THE CWA AND STRETCHING NORTHWARD INTO MONTANA. THIS IS STRENGTHENING THE PRESSURE GRADIENT ACROSS SOUTHEAST WYOMING AND SETTING THE STAGE FOR STRONG WINDS TO OCCUR TONIGHT. CROSS SECTION PLOTS FROM ARLINGTON TO TORRINGTON CONTINUE TO SHOW WESTSOUTHWEST WINDS INCREASING IN THE 600-700 MB LAYER WITH 50 TO 60KT BARBS COMMON OVERNIGHT. AN INCREASINGLY STRONG INVERSION IS NOW EVIDENT IN THIS LAYER WHICH IS LIKELY CONTRIBUTING TO THE STRONGER WINDS...IN ADDITION TO THE SHORTWAVE APPROACHING THE REGION FROM THE NW. WITH THE INVERSION...GOING TO SEE TRAPPING OF THE STRONGER FLOW IN THE LLVLS WITH LOCALIZED FORCING OF WINDS THROUGH THE GAPS. THEREFORE HIGH WIND WARNING LOOKS GOOD TO CAPTURE THIS EVENT...WITH WINDY CONDITIONS ALBEIT NOT AS STRONG OCCURRING IN THE FOOTHILLS OF THE SOUTHERN LARAMIE RANGE THROUGH MONDAY MORNING AS WELL. AS THE SHORTWAVE CONTINUES TO TREK EAST ON MONDAY...WILL SEE THE LEE TROUGH MOVE EAST AS WELL WITH WEAK HIGH PRESSURE AND COOLER TEMPS BUILDING IN FROM THE NORTHWEST. WINDS WILL DECREASE QUITE A BIT AS THIS OCCURS. 80 TO 100KT NW WINDS AT 250MB WILL MOVE OVERHEAD MONDAY NIGHT AS A SHORTWAVE RIDGE BUILDS ACROSS THE WEST. YET ANOTHER SHORTWAVE CLIPPER SYSTEM WILL MOVE TOWARD THE ROCKIES EARLY TUESDAY MORNING AND WILL BE OVER WYOMING/WESTERN NEBRASKA BY THE EARLY AFTERNOON. SO WILL ONCE AGAIN SEE WINDS ON THE INCREASE THRU THIS TIME PERIOD. LOOKS LIKE ANOTHER ROUND OF HIGH WIND WARNINGS MAY BE NEEDED FOR TUESDAY MORNING. HIGH PRESSURE WILL BUILD FURTHER SOUTH THIS TIME ACROSS UTAH AND COLORADO...SO EVEN THOUGH THE LEE TROUGH LOOKS TO SHIFT EAST AGAIN WITH THE SHORTWAVE IN THE AFTERNOON...THE GRADIENT WILL NOT RELAX MUCH. THUS STRONG AND GUSTY WINDS WILL VERY LIKELY PERSIST IN THE WIND CORRIDOR THROUGH TUESDAY NIGHT. SOME DEEPER MOISTURE WILL BE ASSOCIATED WITH THIS SYSTEM SO COULD SQUEEZE OUT SOME SNOWFALL ALONG THE WESTERN SLOPES OF THE MOUNTAINS ON TUESDAY. TEMPERATURES OVERALL WILL REMAIN ON THE MILD SIDE IN THE 30S AND 40S FROM WEST TO EAST. LONG TERM...WEDNESDAY THROUGH SATURDAY... CHANGE IN THE WEATHER PATTERN UNDER WAY FROM SPLIT FLOW TO STRONG ZONAL FLOW OVER THE NORTHERN CONUS. THIS WILL HAVE IMPLICATIONS THROUGH THE EXTENDED FORECAST PERIOD. THE LAST OF SEVERAL CLOSED AND CUT OFF LOWS WHICH CYCLED DOWN THE WEST COAST AND INTO THE PLAINS WILL MOVE OUT INTO THE PLAINS MONDAY. AT THE SAME TIME ONE OF SEVERAL SHORTWAVES LINED UP ACROSS THE PACIFIC WILL MOVE ASHORE OVER THE PACIFIC NORTHWEST. FAST MOVING ZONAL FLOW WILL ALLOW ONE SHORTWAVE AFTER THE OTHER TO AFFECT THE FORECAST AREA RIGHT INTO NEXT WEEKEND. CHANCES FOR PRECIPITATION IN THIS WEATHER PATTERN WILL BE MINIMAL WITH THE EXCEPTION OF UPSLOPE FAVORED AREAS ACROSS THE SNOWY AND SIERRA MADRES. THE BIGGEST CHANGE WITH THE ZONAL FLOW PATTERN WILL BE WIND SPEEDS. EXPECTING SEVERAL DAYS WITH VERY STRONG WESTERLY WINDS. WINDS WILL COMMONLY REACH SUSTAINED 30 TO 40 MPH WITH GUSTS OF 50 TO 60 MPH ACROSS MUCH OF SOUTHEAST WYOMING...ESPECIALLY IN FAVORED HIGH WIND LOCATIONS SUCH AS VEEDAWOO...ARLINGTON...AND BORDEAUX. 70 MPH OR GREATER GUSTS ARE A POSSIBILITY IN THESE LOCATIONS AS WELL...BUT TIMING OF WHEN THAT MAY OCCUR IS YET TO BE DETERMINED...AS EXACT TIMING OF SHORTWAVE ENERGY IS MUCH TO BE DESIRED IN THIS WEATHER PATTERN. IN SUMMARY...DRY AND VERY WINDY THROUGH THE NEXT 7 DAYS. ALSO OF NOTE...TEMPERATURES AT TO ABOVE NORMAL THROUGH THE EXTENDED PERIOD. FIRE WEATHER...NO FIRE WEATHER CONCERNS EXPECTED FOR THE NEAR FUTURE DUE TO THE RECENT SNOWFALL...NON CRITICAL FUELS AND MINIMUM RELATIVE HUMIDITIES THAT WILL BE 25 PERCENT OR GREATER THROUGH THE WEEK. WINDY CONDITIONS WILL BEGIN LATER TONIGHT FOR THE TYPICAL WINDY AREAS FROM ARLINGTON THROUGH BORDEAUX. THESE WINDS WILL PERSIST PERIODICALLY THROUGH ALL OF NEXT WEEK. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...HIGH WIND WARNING UNTIL 9 AM MONDAY FOR WYZ106-WYZ110. NE...NONE. && SHORT TERM/FIRE WEATHER...RJM LONG TERM/AVIATION...LIEBL
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHEYENNE WY 955 PM MST SUN DEC 25 2011 WYZ101>119-270500- CONVERSE COUNTY LOWER ELEVATIONS-NIOBRARA COUNTY- NORTH LARAMIE RANGE-FERRIS/SEMINOE/SHIRLEY MOUNTAINS- SHIRLEY BASIN-CENTRAL LARAMIE RANGE AND SOUTHWEST PLATTE COUNTY- EAST PLATTE COUNTY-GOSHEN COUNTY-CENTRAL CARBON COUNTY- NORTH SNOWY RANGE FOOTHILLS-SOUTHWEST CARBON COUNTY- SIERRA MADRE RANGE-UPPER NORTH PLATTE RIVER BASIN-SNOWY RANGE- LARAMIE VALLEY-SOUTH LARAMIE RANGE-SOUTH LARAMIE RANGE FOOTHILLS- CENTRAL LARAMIE COUNTY-EAST LARAMIE COUNTY- 955 PM MST SUN DEC 25 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST CENTRAL WYOMING... SOUTH CENTRAL WYOMING AND SOUTHEAST WYOMING. .DAY ONE...TONIGHT STRONG WINDS WILL DEVELOP ACROSS THE WIND CORRIDOR OF SOUTHEAST WYOMING TONIGHT AND CONTINUE THROUGH MONDAY MORNING. THIS INCLUDES THE ARLINGTON AREA EASTWARD TO INTERSTATE 25 NEAR THE BORDEAUX EXIT. A HIGH WIND WARNING IS IN EFFECT FOR THIS AREA THROUGH 9AM MONDAY FOR SOUTHWEST WINDS EXPECTED TO BE SUSTAINED AT 35 TO 45 MPH WITH GUSTS APPROACHING 60 MPH. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY WINDY CONDITIONS WILL CONTINUE ACROSS THE WIND CORRIDOR OF SOUTHEAST WYOMING...AND SPREAD TO THE EASTERN FOOTHILLS OF THE LARAMIE RANGE AND ADJACENT PLAINS AT TIMES DURING THE WEEK. STRONGEST WINDS CONTINUE TO LOOK LIKELY IN THE WEDNESDAY THROUGH FRIDAY TIMEFRAME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TONIGHT. && THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC...AND CLIMATE INFORMATION IS AVAILABLE ON THE WEB AT... HTTP://WEATHER.GOV/CHEYENNE NEZ002-003-019>021-054-055-095-096-270500- DAWES-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-KIMBALL-CHEYENNE- NORTH SIOUX-SOUTH SIOUX- 955 PM MST SUN DEC 25 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA PANHANDLE. .DAY ONE...TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY THE PROBABILITY OF WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TONIGHT. && THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC...AND CLIMATE INFORMATION IS AVAILABLE ON THE WEB AT... HTTP://WEATHER.GOV/CHEYENNE
The national radar mosaic for the moment the first event began.
7 high wind. Local standard time, as filed.
The WYDOT site at Halleck Ridge measured sustained winds of 40 mph or greater, with a peak gust of 59 mph at 26/0410L.
The WYDOT site at Arlington measured sustained winds of 40 mph or greater, with a peak gust of 60 mph at 26/0721L.
The UPR site at Emkay measured sustained winds of 40 mph or greater, with a peak gust of 69 mph at 26/0430L.
The WYDOT site at Wyoming Hill measured wind gusts of 60 mph.
The WYDOT site at Bordeaux measured wind gusts to 58 mph.
The UPR site at Lynch measured sustained winds of 40 mph or greater, with a peak gust of 59 mph at 26/0545L.
The WYDOT site at Strouss Hill measured wind gusts of 63 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2011Every state in 2011This day in weather historyWarnings in Wyoming, December 2011
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: 353256, 353255, 353260, 353261, 353254, 353259, 353257.