A surge of sub-tropical moisture combined with a trough moving south out of Canada to bring heavy snow to many areas east of the Continental Divide. Snowfall exceeding six inches was fairly widespread.
Every event with a place to put it; 6 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 surge of sub-tropical moisture combined with a trough moving south out of Canada to bring heavy snow to many areas east of the Continental Divide. Snowfall exceeding six inches was fairly widespread. The highest amounts fell in the favored north to northeast upslope locations such as Lander, the southern Big Horn Basin, and the Casper area. The highest snowfall total was 13 inches northeast of Thermopolis near the community of Lucerne. Portions of Casper received 10 inches of snow with areas around Lander receiving 6 to 9 inches.
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 13, 10:20 PM MST, 2 hours 40 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 1020 PM MST SAT DEC 13 2014 .SHORT TERM...TONIGHT THROUGH SUNDAY (ISSUED AT 219 PM MST) MAIN LONG WAVE TROUGH EXTENDS SOUTH FROM BRITISH COLUMBIA SOUTH THROUGH ARIZONA INTO NORTHWEST MEXICO. SOUTHERN PORTION OF LOW OVER NORTHWEST ARIZONA BEGINNING PROCESS OF CUTTING OFF WHILE NORTHERN PORTION OF THE TROUGH OVER THE PACIFIC NORTHWEST AND NORTHERN ROCKIES SHOWING SIGNS OF SLOWING DOWN WITH TROUGH BECOMING NEGATIVELY TILTED AS THE SOUTHERN PORTION MOVES MUCH FASTER TO THE EAST. VERY STRONG UPPER DIVERGENCE AND DEEPER SUBTROPICAL PACIFIC MOISTURE DEVELOPING DEEP CONVECTION TO THE EAST OF THE SOUTHERN PORTION OF THE TROUGH OVER NORTHWEST ARIZONA...EASTERN UTAH AND WESTERN WYOMING SPREADING NORTH INTO SOUTHWEST WYOMING. ONE AREA OF MORE WIDESPREAD SNOW SHOWERS MOVED THROUGH THE WEST AND SOUTHWEST THIS MORNING WITH A GREATER AREA NOW FORMING OVER NORTHERN UTAH AND NORTHWEST COLORADO SHOULD SWEEP NORTH INTO SOUTHWEST WYOMING THIS AFTERNOON AND THIS EVENING WITH MORE WIDESPREAD AND POSSIBLY HEAVY SNOW SPREADING NORTH ACROSS SWEETWATER COUNTY INTO SOUTHERN FREMONT AND SOUTHERN NATRONA COUNTIES. SURFACE PRESSURE FALLS ARE WIDESPREAD FROM NORTHERN MEXICO INTO SOUTHERN SASKATCHEWAN EAST OF THE UPPER LEVEL LOW PRESSURE TROUGH. DEVELOPMENT OF A SURFACE TO 700 MB LOW IS EXPECTED OVER NORTHWEST COLORADO WITH AN OCCLUSION AND TROWAL DEVELOPING ACROSS SOUTHERN WYOMING. THIS DEVELOPMENT WHICH HAS BEEN SHOWN BY THE MODELS SINCE THURSDAY WITH VARYING DEGREES OF CHANGE FROM MODEL RUN TO MODEL RUN WILL BE THE MOST CRITICAL FEATURE DRIVING THE CURRENT FORECAST OF SNOW AND WIND WITH THE WINTER WEATHER ADVISORIES IN PLACE. AT THIS TIME THE RAPIDLY COOLING CLOUD TOPS AND DEEP CONVECTION DEVELOPING IN THIS GENERAL AREA INCREASES THE CURRENT CONFIDENCE IN THE OVERALL DEVELOPMENT ACTUALLY OCCURRING TONIGHT AND SUNDAY. .LONG TERM...SUNDAY NIGHT THROUGH SATURDAY SNOWFALL ASSOCIATED WITH THE AREA OF LOW PRESSURE WILL REMAIN PEGGED TO CENTRAL AND EASTERN WYOMING SUNDAY NIGHT. THE AREA OF LOW PRESSURE WILL MOVE FURTHER INTO THE CENTRAL PLAINS...HELPING TO ALLEVIATE SNOWFALL ACTIVITY ACROSS THE STATE BY MONDAY AFTERNOON. A TRANSITORY RIDGE WORKS TO BUILD OVER THE STATE MONDAY NIGHT HELPING TO KEEP DRY...AND SLIGHTLY WARMER CONDITIONS ACROSS CENTRAL AND WESTERN WYOMING. MEANWHILE...THE NEXT APPROACHING WAVE OF LOW PRESSURE WILL MOVE OFF THE CALIFORNIA COAST TUESDAY EVENING. THIS SYSTEM WILL MOVE FURTHER EASTWARD THROUGH THE OVERNIGHT HOURS...HELPING TO BRING SOME LIGHT SNOWFALL ACROSS THE WESTERN MOUNTAINS AND VALLEYS BY WEDNESDAY MORNING. MODELS DIVERGE A BIT ON THIS SYSTEM...ESPECIALLY WHEN DECIDING HOW FAR SOUTH THE SYSTEM WILL DIVE WEDNESDAY NIGHT THROUGH THURSDAY MORNING. RESULTING PLACEMENT ALTERS SNOWFALL COVERAGE ACROSS THE STATE...BUT WITH MOST SOLUTIONS WE STILL SEE SOME SNOWFALL ACROSS THE WESTERN MOUNTAINS AND VALLEYS PERSISTING INTO THURSDAY. ANOTHER WEAK TRANSITORY RIDGE BUILDS OVER THE INTERMOUNTAIN WEST THURSDAY EVENING AND INTO FRIDAY...WITH DRIER CONDITIONS MOVING IN TO THE CWA BY FRIDAY MORNING AND AFTERNOON. AGAIN...MODELS DIVERGE ON THE PATH AND SPEED OF THE NEXT SYSTEM. THE GFS CLOSES OFF THE ENERGY INTO A LOW PRESSURE SYSTEM AND HAS IT DIVING MUCH FURTHER SOUTH. THIS SOLUTION WOULD KEEP ANY SNOWFALL ACROSS THE CWA MAINLY ACROSS THE SOUTHWESTERN CORNER. THE ECMWF MEANWHILE...KEEPS THE SYSTEM AN OPEN WAVE...WITH SNOWFALL IMPACTING THE WESTERN MOUNTAINS AND VALLEYS THROUGH THE WEEKEND. FORECAST KEEPS MENTION OF LIGHT POPS ACROSS THE AREA WHILE MODELS WORK OUR THEIR DISAGREEMENTS. ALMOST REGARDLESS OF SOLUTION...TEMPERATURES ARE EXPECTED TO COOL A BIT THROUGH THE PERIOD...WITH SLIGHT WARMUP ANTICIPATED DURING THE TRANSITORY RIDGES. && .AVIATION.../06Z ISSUANCE/ EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES AS SNOW DEVELOPS OVERNIGHT...MVFR AND IFR CONDITIONS WILL PREVAIL BY 12Z OVER THE REGION. THESE CONDITIONS WILL CONTINUE THROUGH 06Z MONDAY IN MOST LOCATIONS. EXPECT MOUNTAIN OBSCURATION THROUGH THE PERIOD. WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES AREAS OF SNOW WILL CONTINUE OVERNIGHT AND THROUGH SUNDAY. SNOW SHOWERS WILL OCCUR SUNDAY NIGHT. EXPECT SOME MOUNTAIN OBSCURATION AS WELL AS AREAS OF MVFR AND IFR CONDITIONS. && .FIRE WEATHER... COLD WINDY SNOWY WEATHER IS IN STORE FOR THE AREA TONIGHT THROUGH SUNDAY EVENING WITH GRADUALLY IMPROVING CONDITIONS STARTING IN THE WEST AND GRADUALLY SPREADING EAST SUNDAY AFTERNOON AND EVENING. TEMPERATURES WILL BE COLDER ACROSS THE AREA. LOW MIXING HEIGHTS WILL RESULT IN POOR SMOKE DISPERSAL OVER THE AREA. PLEASE REFER TO THE WINTER WEATHER ADVISORIES AND SPECIAL WEATHER STATEMENTS THAT HAVE BEEN ISSUED FOR DETAILS OF FORECAST SNOWFALL AND WIND IN YOUR SPECIFIC AREA. && .RIW WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 5 PM MST SUNDAY WYZ020-022. WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 3 PM MST SUNDAY WYZ015-017>019-030. && SHORT TERM...C.BAKER LONG TERM...BRANHAM AVIATION...AR FIRE WEATHER...C.BAKER
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 500 AM MST SAT DEC 13 2014 WYZ001>020-022>030-141200- 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 SAT DEC 13 2014 THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. ...WINTER WEATHER ADVISORY FOR EASTERN SWEETWATER...SOUTHERN AND EASTERN FREMONT AND SOUTHERN NATRONA COUNTIES FROM MIDNIGHT TONIGHT THROUGH SUNDAY AFTERNOON... .DAY ONE...TODAY AND TONIGHT INCREASING LIGHT TO OCCASIONALLY MODERATE SNOW ACROSS THE WEST. HEAVIEST SNOW IS EXPECTED FROM THE SOUTHWEST MOUNTAINS NORTH TO SOUTHWESTERN YELLOWSTONE NATIONAL PARK THIS MORNING...BEFORE SHIFTING ACROSS WESTERN SWEETWATER COUNTY AS WELL AS PORTIONS OF THE UPPER GREEN RIVER BASIN AND WESTERN WIND RIVER MOUNTAINS THIS AFTERNOON. TONIGHT...SOME POSSIBLE RAIN EARLY WILL MIX WITH SNOW BEFORE BECOMING ALL SNOW EAST OF THE DIVIDE OVERNIGHT. SNOW MAY BECOME HEAVY AT TIMES BEFORE SUNRISE. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY SUNDAY AND SUNDAY NIGHT...LIGHT SNOW ACROSS THE WEST. MODERATE TO OCCASIONALLY HEAVY SNOW CONTINUES FOR MANY AREAS EAST OF THE DIVIDE AND SOUTH OF THE BIGHORN BASIN...WITH THE BEST CHANCE FOR SEVERAL INCHES OF SNOWFALL LOCATED SOUTH AND EAST OF LANDER...TO WORLAND...TO GILLETTE LINE...INCLUDING PORTIONS OF INTERSTATE 80 EAST OF ROCK SPRINGS AND THE INTERSTATE 25 CORRIDOR NORTH OF CASPER. SNOW WILL TAPER OFF SUNDAY NIGHT. .SPOTTER INFORMATION STATEMENT... PLEASE REPORT SNOWFALL AMOUNTS. THANK YOU. TEAM RIVERTON
The national radar mosaic for the moment the first event began.
6 winter storm. Local standard time, as filed.
Trained spotters measured 6 to 7 inches of snow in Jeffrey City and Sweetwater Station.
Snowfall in the vicinity of Lander generally ranged from 5 to 9 inches.
Snowfall amounts across the southeast Big Horn Basin ranged from 7 inches near Worland to 12 inches south of Ten Sleep in the Upper Nowood Valley.
Trained spotters reported 6 inches of snow in Cody. The highest amount in the area was report east of Cody where over 10 inches fell.
The observer at Casper airport measured 9.3 inches of snow. Other locations around Casper measured from 7 to 11 inches of snow.
Heavy snow fell across portions of Hot Springs County. The highest amount was 9 miles NE of Thermopolis near Lucerne where 13 inches of snow was measured.
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: 548998, 548999, 549001, 549002, 548997, 549000.