A slow-moving storm system moved out of Utah and across southern Wyoming producing a period of heavy snow on Christmas Day. Low-to-mid level wind flow was from the northeast and favored upslope conditions across Hot Springs, Fremont, and Natrona counties.
Every event with a place to put it; 10 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 slow-moving storm system moved out of Utah and across southern Wyoming producing a period of heavy snow on Christmas Day. Low-to-mid level wind flow was from the northeast and favored upslope conditions across Hot Springs, Fremont, and Natrona counties. Snow totals ranged from 7 to 13 inches in these areas. The northern portions of both the Jackson and Star valleys reported snowfall of around one foot. The highest amounts of one to two feet fell in the foothills of the Wind River Range near Lander and on Casper Mountain. The same cold front that produced the favorable upslope flow also brought gusty northeast winds to the basins east of the Continental Divide beginning early Christmas morning. Northeast wind of 20 to 30 mph was common. The strongest wind was in Sweetwater County where sustained speeds of 30 to 40 mph and gusts to 51 mph combined with the snow to produce treacherous driving conditions on Interstate 80.
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 Dec 24, 3:07 PM MST, 53 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 307 PM MST WED DEC 24 2014 .SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT THE LONG AWAITED CHRISTMAS SNOW STORM IS NIPPING AT OUR HEELS WITH SNOW ALREADY FALLING IN CENTRAL IDAHO AS OF EARLY WEDNESDAY AFTERNOON. THIS SWATH OF INITIAL SNOW WILL OVERSPREAD THE WESTERN MOUNTAINS BY MIDNIGHT TONIGHT WITH SOME SNOW BEGINNING TO WRAP AROUND INTO NORTHERN WYOMING SHORTLY THEREAFTER. THERE WILL BE A GOOD BURST OF SNOW WITH THE FRONT AS IT DROPS SOUTH INTO THE REGION OVERNIGHT...THROUGH THE BIGHORN BASIN EARLY IN THE MORNING AND THEN THROUGH THE CENTRAL BASINS AROUND SUNRISE CHRISTMAS MORNING. THERE WILL BE SEVERAL HOURS OF STEADY SNOW BEHIND THE FRONT AS REINFORCEMENTS ARRIVE AS THE UPPER WAVE ARRIVES ALONG WITH A GOOD SWATH OF STRONG QG FORCING. LAYER TEMPERATURES ALL THE WAY THROUGH THE ATMOSPHERE WILL BE FAVORABLE FOR DENDRITIC GROWTH AS THE FRONT PASSES AS WELL AS SEVERAL HOURS AFTERWARD. HOWEVER THE ATMOSPHERE BECOMES COOLER AND DRYER AFTER 21Z THURSDAY WHICH WILL INCREASE SNOW RATIOS BUT IT WILL END THE FAVORABLE HEAVY SNOW ENVIRONMENT. WINDS WILL BE FAIRLY STEADY WITH THE FRONT AT 15 TO 25 MPH IN MOST AREAS WITH SOME GUSTY SPOTS...SPECIFICALLY AROUND COWLEY AND BUFFALO AS WELL AS THROUGH WIND RIVER CANYON EARLY IN THE MORNING. THE GUSTY WIND WILL THEN SHIFT TO SOUTH PASS AND INTO EASTERN SWEETWATER COUNTY...LIKELY IMPACTING TRAVEL ALONG INTERSTATE 80 EAST OF ROCK SPRINGS THROUGH THE DAY. IN ADDITION...THERE WILL BE SIGNIFICANT BLOWING SNOW THROUGH JOHNSON AND NATRONA COUNTIES IN THE AFTERNOON AS NORTH WINDS BECOME STEADY AT AROUND 25MPH. THE SNOW WILL TAPER OFF CHRISTMAS NIGHT INTO FRIDAY WITH SNOW CLEARING FROM NORTH TO SOUTH. WINDS WILL BE RELATIVELY LIGHT ON FRIDAY WITH SKIES REMAINING PARTLY TO MOSTLY CLOUDY AS ANOTHER WEAK DISTURBANCE SWINGS SOUTH. IT WILL NOT RESULT IN MUCH ADDITIONAL SNOWFALL BUT THERE COULD BE SOME FLURRIES IN THE MOUNTAINS WITH THIS WAVE. IT WILL HOWEVER KEEP THE TEMPERATURES FROM BOTTOMING OUT BEHIND THE EXITING SYSTEM FRIDAY NIGHT. .LONG TERM...SATURDAY THROUGH THURSDAY BY 00Z FRIDAY...THE SNOWFALL WILL SLOWLY BEGIN TO END FROM NORTH TO SOUTH AND DECREASE IN INTENSITY SOMEWHAT...EXCEPT IN THE UPSLOPE FAVORED REGIONS EAST OF THE DIVIDE. THE MID LEVEL CIRCULATION WILL STILL BE OVER SOUTHWEST WY AT 00Z FRIDAY ALONG WITH LINGERING ISENTROPIC LIFT FROM NORTH TO SOUTH AS WELL AS LINGERING SUFFICIENT QG FORCING. WE WILL BEGIN TO LOSE THESE DYNAMICS AFTER FEW HOURS AFTER SUNSET AS THE SYSTEM PULLS AWAY TO THE SOUTHEAST. HOWEVER...AS THE 700MB LEVEL LOW MOVES OFF TO OUR SOUTH OVER COLORADO...THE WINDS WILL BACK TO THE NORTHEAST AT 700MB AND INCREASE FOR ENHANCED UPSLOPE FLOW IN AREAS LIKE LANDER...CASPER AND THERMOPOLIS. AFTER 06Z...THE SNOWFALL SHOULD DECREASE EVERYWHERE. ON FRIDAY...EXCEPT FOR SOME LINGERING ISOLATED MTNS FLURRIES...EXPECT DRY WEATHER. DRY WEATHER IS EXPECTED FRIDAY NIGHT. ON SATURDAY...LIGHT SNOW WILL ONCE AGAIN DEVELOP IN FAR WEST WYOMING AS A VORT LOBE IN THE NORTHWEST FLOW ON THE BACKSIDE OF THE MAIN EXITING TROUGH TRACKS ACROSS THE AREA AND THE INCREASINGLY DIFLUENT NW FLOW INCREASES THE UPSLOPE POTENTIAL. THIS UPSLOPE FLOW WILL INCREASE SATURDAY NIGHT WITH SNOW INCREASING IN THE WEST AS THE TROUGH...NOW JUST EAST OF THE ALEUTIANS...DIVES SOUTHEAST AND DEEPENS OVER THE PACIFIC NORTHWEST. BY SUNDAY MORNING...THE TROUGH WILL BEGIN TO CLOSE OFF ALONG THE WASHINGTON OREGON BORDER AND SNOWFALL WILL BECOME MORE WIDESPREAD AND INTENSIFY OVER THE WEST. BY SUNDAY AFTERNOON...SNOWFALL WILL BEGIN TO SPILL OVER EAST OF THE DIVIDE WITH THE H5 AND THE H7 LOW OVER IDAHO PER GFS SOLN. THEN THE ENERGY WITH THE ASCT TROUGH WILL SPLIT WITH THE IDAHO LOW TRACKING DOWN TO VEGAS BY 12Z TUESDAY. BY THIS TIME THE TROUGH AXIS WILL BE OVERHEAD. THE NORTHERN STREAM ENERGY WILL PULL DOWN THE COLDEST ARCTIC AIR OF THE SEASON INTO WYOMING TUESDAY. BITTER COLD ADVECTION WILL ACCOMPANY THE FRONT MON/TUESDAY. IN THE MEANTIME...CHC POPS ARE IN THE FORECAST FOR MOST AREAS WITH THE APPROACHING TROUGH FOR SUNDAY NIGHT WITH LIKELY POPS IN THE WEST AND BIG HORN MTNS. SNOW WILL DECREASE MONDAY AS THE ENERGY SPLITS. AS ALLUDED TO ABOVE...TUE WILL FEATURE STEADY OR FALLING TEMPERATURES AFTER A FRIGID MORNING WITH VERY COLD WIND CHILLS AS THE POST FRONTAL AIR WORKS ITS WAY INTO THE NORTH AS A 1048MB SFC HIGH DRIVES THE FRIGID AIR SOUTH. TEMPS WILL CONTINUE TO DROP TUESDAY NIGHT AS SKIES CLEAR AND WINDS DIMINISH. WARM AIR ADVECTION ALOFT IS EXPECTED FROM THE NW WEDNESDAY WHICH WILL ONLY STRENGTHEN THE COLD AIR INVERSIONS IN THE BASINS AND VALLEYS FOR WEDNESDAY MORNING WITH SOME AREAS EAST AND WEST OF THE DIVIDE SEEING TEMPS AS LOW AS 30 BELOW OR A LITTLE COLDER. THE EURO...ON THE OTHER HAND...UNLIKE YESTERDAYS RUN...IS DIVERGING AWAY FROM THE GFS SOLN WHICH IS TO BRING A SHORTWAVE TROUGH THROUGH SUNDAY AND ANOTHER ONE TUESDAY. AM IGNORING THIS SOLN ATTM BUT...IF NOTHING ELSE...IS ANOTHER REASON TO SAVE THE COLDEST AIR FOR WEDNESDAY MORNING IN THE FORECAST AFTER THE COLDEST WIND CHILLS OCCUR TUESDAY MORNING. THE GFS IS ADVERTISING H7 TEMPS OF -28C WITH THE EURO SHOWING -32C MOVING INTO WY FROM THE NORTH AT H7 ON TUE. && .AVIATION.../00Z ISSUANCE/ A TROUGH OF LOW PRESSURE WILL MOVE ONTO THE GREAT BASIN TONIGHT. EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES A LEE SIDE SURFACE TROUGH WILL CONTINUE TO COINCIDE WITH SOUTHWEST WINDS OF 25 TO 35 KTS MPH WITH GUSTS OF 40 TO 45 KTS THROUGH 02Z THIS EVENING FROM VCNTY 50NE KRKS- KCPR. GUSTY W-SW WINDS ALONG THE EAST SLOPES OF THE DIVIDE WILL ALSO RESULT IN SOME LLWS FROM VCNTY KCOD-KLND DURING THIS TIME FRAME. A COLD FRONT WILL PUSH SOUTH INTO NORTHERN WYOMING 3-6Z TONIGHT AND TO A VCNTY KLND-KCPR LINE 10Z-12Z THURSDAY. WIDESPREAD MVFR/IFR CIGS AND VSBYS IN -SN...HIGHER TERRAIN OBSCD...WILL SPREAD ACROSS THE AREA WITH THE FRONTAL PASSAGE. WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES VCNTY KJAC- KAFO...-SN EXPECTED OVR THE MTNS BECOMING INCREASINGLY OBSCURED THROUGH 01Z THIS EVENING AS THE SNOWFALL MAKES ITS WAY ONTO THE VALLEY FLOORS DURING THIS TIME FRAME. MORE WIDESPREAD IFR SN WILL SPREAD NW-SE ACROSS THE WEST AFTER 01Z THIS EVENING...SPREADING SOUTH OF A KEVW-KBPI LINE MAINLY AFTER 06Z THURSDAY. && .FIRE WEATHER... WIDESPREAD SNOW AND GUSTY WIND THROUGH EARLY FRIDAY MORNING. BASINS AND VALLEYS WILL QUICKLY BECOME TRAPPED ON FRIDAY NIGHT WITH VERY POOR SMOKE DISPERSION. ON SATURDAY...MILDER AIR MOVES IN ALONG WITH SOME STRONGER WINDS THAT WILL ENCOURAGE SOME MIXING. ANOTHER SNOW STORM IS POSSIBLE ON SUNDAY INTO MONDAY. && .RIW WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING FROM 5 AM TO 11 PM MST THURSDAY WYZ015-017>020-022-027>030. WINTER WEATHER ADVISORY UNTIL 8 PM MST THURSDAY WYZ001-002-012>014-023-024. WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 8 PM MST THURSDAY WYZ003-004-006-008>011-016. WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 8 PM MST THURSDAY WYZ025-026. WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 8 PM MST THURSDAY WYZ005-007. && SHORT TERM...ALLEN LONG TERM...LIPSON AVIATION...LIPSON FIRE WEATHER...ALLEN
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 1259 PM MST WED DEC 24 2014 WYZ001>020-022>030-251300- 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- 1259 PM MST WED DEC 24 2014 ...WINTER STORM WARNINGS AND WINTER WEATHER ADVISORIES FOR WESTERN AND CENTRAL WYOMING FROM TONIGHT THROUGH CHRISTMAS DAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT SNOW WILL DEVELOP ACROSS THE WEST LATER THIS AFTERNOON AND SPREAD EAST OF THE DIVIDE LATE TONIGHT. SEE WINTER WEATHER PRODUCTS FOR DETAILS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY CHRISTMAS DAY...A WINTER STORM IS LIKELY WITH SEVERAL INCHES OF SNOW LIKELY. PLEASE SEE WINTER WEATHER PRODUCTS FOR DETAILS. SATURDAY NIGHT...SNOW DEVELOPS OVER THE WEST. SUNDAY AND SUNDAY NIGHT...A NEW WEATHER SYSTEM SPREADS SNOW ACROSS THE REGION. TRAVEL MAY BE IMPACTED BY THIS SYSTEM...ESPECIALLY SUNDAY NIGHT. MONDAY AND TUESDAY...SNOW DECREASES MONDAY AFTERNOON. VERY COLD TEMPERATURES WILL OCCUR MONDAY AND TUESDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT. TEAM RIVERTON
The national radar mosaic for the moment the first event began.
10 winter storm. Local standard time, as filed.
Heavy snow fell in the Jackson Valley. Some amounts included 12 inches in Moose and 9 inches in the city of Jackson.
Heavy snow fell across the northern Star Valley. Alpine had 12 inches of snow with 8 inches at Star Valley Ranch. Lesser amounts fell farther south where Afton only measured 2.5 inches of snow.
Heavy snow fell in portions of the Upper Green River Foothills. The heaviest amounts fell west of Daniel where 16 inches was measured. Around a foot of snow was measured around Bondurant. Lesser amounts were noted around Pinedale.
Heavy snow fell in the eastern slopes of the Wind River Range. The highest amounts fell in Sinks Canyon State Park where snowfall of 14 to 20 inches was measured.
Heavy snow fell in portions of Casper nearest Casper Mountain. Snowfall in this area ranged from 7 to 11 inches. Lesser amounts of 4 to 6 inches fell in other portions of the Casper area.
Snowfall of 12 to 18 inches was measured on Casper Mountain.
Heavy snow fell throughout Hot Springs County. The heaviest amounts were near Thermopolis where totals were 12 to 16 inches.
The cooperative observer in Jeffrey City measured 6 inches of snow.
In Lander, 7 to 10 inches of new snow fell across town.
Trained spotters measured 5 inches of snow in Green River and Rock Springs. The snow combined with northeast wind of 30 to 40 mph with gusts as high as 51 mph to make for treacherous travel on Interstate 80 across Sweetwater County.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2014Every state in 2014This day in weather historyWarnings in Wyoming, December 2014
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: 549633, 549634, 549635, 549620, 549624, 549626, 549612, 549631, 549629, 549632.