A Pacific storm system produced a prolong period of snow in the higher elevations of southeast Wyoming. A stationary frontal boundary stretching across the area was the focal point for the majority of the snow.
Every event with a place to put it; 13 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.
A Pacific storm system produced a prolong period of snow in the higher elevations of southeast Wyoming. A stationary frontal boundary stretching across the area was the focal point for the majority of the snow.
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 18, 3:13 AM MST, 1 hour 47 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
313 AM MST SAT DEC 18 2010
.SHORT TERM...TODAY THROUGH MONDAY AFTERNOON...CURRENT IR
SATELLITE LOOP SHOWS SKIES BECOMING PARTLY TO MOSTLY
CLOUDY...ESPECIALLY ACROSS WYOMING WITH VERY CHILLY TEMPS EARLY
THIS MORNING. OBS SHOW TEMPS IN THE SINGLE DIGITS AND TEENS...WITH
SOME AREAS NORTHEAST OF I80 BELOW ZERO THIS MORNING WHERE SKIES
ARE MOSTLY CLEAR. LIGHT SNOW IS DEVELOPING ACROSS THE MOUNTAINS
AND POINTS WEST ACROSS WRN WYOMING...UTAH...AND NEVADA. RAWLINS
HAS EVEN REPORTED SOME LIGHT SNOW AROUND MIDNIGHT AS WELL. THIS
ACTIVITY IS AHEAD OF A WARM FRONT PUSHING EASTWARD ACROSS THE WRN
UNITED STATES AND IS ASSOCIATED WITH A STRONG STORM SYSTEM ACROSS
THE EASTERN PACIFIC. THIS FRONT IS EXPECTED TO STALL ACROSS
SOUTHEAST WYOMING AS VIGOROUS UPPER LEVEL DISTURBANCES EMBEDDED IN
A STRONG PACIFIC JET ALOFT PUSH EAST NORTHEASTWARD ACROSS THE
REGION THROUGH SUNDAY AND MONDAY. FOR TODAY...EXPECT CLOUDS TO
CONTINUE TO INCREASE ACROSS THE AREA WITH LIGHT SNOW IN THE
MOUNTAINS AND PERIODS OF LIGHT SNOW IN THE VALLEYS OF CARBON AND
ALBANY COUNTY DUE TO WARM AIR ADVECTION ALOFT AND OVERRUNNING.
PRECIP IS EXPECTED TO BE LIGHT THROUGH THIS EVENING WITH 3 TO 6
INCHES OF SNOW IN THE MOUNTAINS...AND MAYBE UP TO AN INCH OF SNOW
IN THE VALLEYS WEST OF THE LARAMIE RANGE. A DUSTING TO MAYBE A
HALF INCH OF SNOW IS POSSIBLE EAST OF THE LARAMIE RANGE WHERE POP
IS THE LOWEST...AROUND 20 PERCENT INTO THIS EVENING. HIGH TEMPS
WILL REMAIN WELL BELOW NORMAL ACROSS THE REGION WITH 20S AND
AROUND 30 EXPECTED.
BY LATE TONIGHT...THE FRONTAL BOUNDARY WILL STALL ACROSS SOUTHERN
WYOMING WITH MODELS SHOWING STRONG UPSLOPE FLOW AND LLVL
CONVERGENCE ACROSS SOUTHERN CARBON AND ALBANY COUNTIES. WITH
FAVORABLE LLVL AND UPPER LEVEL DYNAMICS...ISSUED A WINTER STORM
WATCH FOR THE SIERRA MADRE AND SNOW RANGES STARTED 12Z
SUNDAY...AND CONTINUING THROUGH SUNDAY NIGHT INTO MONDAY FOR A
PROLONGED PERIOD OF MODERATE TO HEAVY SNOWFALL. GFS AND NAM SHOW
700-500MB OMEGA BETWEEN 10 TO 15 UB/S IN THIS AREA WITH OMEGA
NEAR 20 UB/S AT TIMES SUNDAY NIGHT. EXPECT HEAVY SNOWFALL IN THE
MOUNTAINS WITH SNOW ACCUMULATIONS OVER ONE FOOT ACROSS WEST FACING
SLOPES THROUGH MONDAY MORNING. THE VALLEYS OF CARBON AND ALBANY
COUNTY WILL BE TRICKY DUE TO DOWNSLOPE WINDS...BUT MAY NEED A
WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW SUNDAY NIGHT AND
MONDAY WITH A FEW INCHES OF SNOW EXPECTED AND STRONG WESTERLY
WINDS. THE HIGH PLAINS EAST OF THE LARAMIE RANGE WILL NEED TO BE
MONITORED AS WELL...SINCE AN ARCTIC BOUNDARY WILL REMAIN OVER THE HIGH
PLAINS NORTHEAST OF A LINE FROM DOUGLAS TO ALLIANCE. GFS SHOWS
SIGNIFICANT PRECIP SUNDAY NIGHT WITH ACCUMULATING SNOW POSSIBLE
ALONG AND NORTH OF THE PINE RIDGE. FOR NOW...INCREASED POP IN MOST
LOCATIONS...ESPECIALLY WEST OF THE LARAMIE RANGE AND NORTH OF THE
NORTH PLATTE RIVER VALLEY ACROSS THE HIGH PLAINS WHERE THE BEST
CHANCES OF ACCUMULATING SNOWFALL WILL BE. BELIEVE ENOUGH WARMER
AIR WILL PUSH INTO EXTREME SOUTHEAST WYOMING AND THE SRN NEBRASKA
PANHANDLE TO CHANGE ANY SNOW TO RAIN OR A RAIN/SNOW MIX NEAR THE
SOUTHERN LARAMIE RANGE. TEMPS WILL BE NEAR OR SLIGHTLY ABOVE
NORMAL NEAR THE COLORADO BORDER...BUT WILL REMAIN BELOW NORMAL
NORTH OF THE NORTH PLATTE RIVER.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY
THE 00Z GFS...ECMWF AND GEM MODELS ARE IN GENERAL AGREEMENT THIS
FORECAST PERIOD WILL BE LARGELY DOMINATED BY A MEAN LONGWAVE
MID/UPPER TROUGH OVER THE EASTERN PACIFIC. THIS TROUGH WILL
CONTINUE TO EJECT SEVERAL SHORTWAVES ACROSS THE GREAT BASIN AND
ROCKIES THROUGH MUCH OF THE UPCOMING WEEK BEFORE CHRISTMAS. THE
EXACT TIMING AND INTENSITY OF THESE SHORTWAVES AND THEIR IMPACTS
ON OUR CWA WILL BE CHALLENGING. THE FIRST SHORTWAVE WILL BE MOVING
NORTHEAST OVER THE CENTRAL ROCKIES AND HIGH PLAINS EARLY IN THE
PERIOD. THE "PINEAPPLE CONNECTION" OR PLUME OF MOISTURE ORIGINATING
FROM THE CENTRAL AND EASTERN PACIFIC WILL STREAM ACROSS CENTRAL AND
SOUTHERN CALIFORNIA AND FOUR CORNERS REGION INTO WYOMING AND
COLORADO. MOST OF THE SIGNIFICANT SNOWFALL WILL BE CONCENTRATED
OVER AND WEST OF THE LARAMIE RANGE MONDAY NIGHT AND TUESDAY...WITH
RAIN/SNOW MIX TO THE EAST WHERE WARMER TEMPERATURES WILL RESIDE.
THE PRECIPITATION WILL SPREAD TO THE NORTHEAST INTO PORTIONS OF
THE NEBRASKA PANHANDLE TUESDAY NIGHT. THE NEXT SHORTWAVE WILL
QUICKLY FOLLOW BEHIND THE FIRST...SPREADING MORE WINTRY PRECIPITATION
ACROSS ALL BUT THE SOUTHEAST THIRD OF THE CWA. THIS SHORTWAVE WILL
EXIT EAST OF THE CWA THURSDAY NIGHT WITH PRECIPITATION ENDING FOR
ALL BUT THE MOUNTAINS OF CARBON COUNTY WHERE OROGRAPHIC SNOW
SHOWERS WILL PERSIST. DRIER CONDITIONS WILL RETURN FRIDAY AND
SATURDAY AS A MID/UPPER RIDGE OVER THE GREAT BASIN MOVES EAST TO
THE CONTINENTAL DIVIDE. TEMPERATURES DURING THE EXTENDED FORECAST
PERIOD WILL AVERAGE 5 TO 10 DEGREES ABOVE NORMAL.
&&
.AVIATION...12Z TAF ISSUANCE
A CHALLENGING FORECAST WITH ONGOING VLIFR CIG/VSBY AT KCDR. MVFR
OR LOWER MAY IMPACT KAIA AND KBFF TOWARD MORNING. CONDITIONS HAVE
IMPROVED TO VFR AT KRWL AFTER A PERIOD OF LOW CIGS AND LIGHT SNOW.
THIS WILL BE TEMPORARY AS MORE MOISTURE WILL SURGE EAST INTO
WYOMING...RESULTING IN DETERIORATING CIGS/VSBYS THERE BY LATE
MORNING...AND KLAR BY MID AFTERNOON. MVFR CIGS AND LIGHT SNOW WILL
GRADUALLY SPREAD EAST INTO EXTREME SOUTHEAST WYOMING AND THE
WESTERN NEBRASKA PANHANDLE DURING LATE AFTERNOON AND EVENING
HOURS. WINDS WILL REMAIN LIGHT AND VARIABLE EAST OF THE LARAMIE
RANGE...BUT INCREASE OUT OF THE SOUTHWEST OVER CARBON COUNTY WITH
GUSTS AOA 25 KT DURING THE AFTERNOON.
&&
.FIRE WEATHER...NO FIRE WEATHER CONCERNS EXPECTED THROUGH THE
WEEKEND AND INTO EARLY NEXT WEEK WITH HIGH HUMIDITIES...COOL
TEMPERATURES...AND PERIODS OF SNOW/RAIN EXPECTED.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WATCH FROM 5 AM SUNDAY TO 11 AM MONDAY FOR WYZ112-
WYZ114.
NE...NONE.
&&
SHORT TERM/FIRE WEATHER...TJT
LONG TERM/AVIATION...JAMSKIThe national radar mosaic for the moment the first event began.
12 winter storm, 1 high wind. Local standard time, as filed.
The SNOTEL at Sage Creek Basin estimated 16 inches of snow for the event.
A COOP observer in Rawlins reported 6 inches of snow. Parts of Rawlins lost power.
Whiskey Park SNOTEL estimated 27 inches of snow for the event.
Little Snake River SNOTEL estimated 31 inches of snow for the event.
Webber Springs SNOTEL estimated 31 inches of snow for the event.
Old Battle SNOTEL estimated 31 inches of snow for the event.
Divide Peak SNOTEL estimated 20 inches of snow for the event.
Brooklyn Lake SNOTEL estimated 32 inches of snow for the event.
Sand Lake SNOTEL estimated 35 inches of snow for the event.
North French Creek SNOTEL estimated 31 inches of snow for the event.
Cinnabar SNOTEL estimated 34 inches of snow for the event.
COOP observer reported 38 inches of snow for event.
A COOP observer recorded a gust of 68 mph 12 SSE of Horse Creek.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2010Every state in 2010This day in weather historyWarnings in Wyoming, December 2010
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: 266826, 266827, 266828, 266829, 266830, 266831, 266832, 266833, 266834, 266835, 266836, 269187, 266837.