Two storm systems moved across western and central Wyoming and brought heavy snow and high wind to the region. The higher elevations of northwest Wyoming saw 12 to 15 inches of snow.
Every event with a place to put it; 4 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.
Two storm systems moved across western and central Wyoming and brought heavy snow and high wind to the region. The higher elevations of northwest Wyoming saw 12 to 15 inches of snow. Snow totals in Star Valley reached 8 inches in a swath from Thayne to Star Valley Ranch. Wind gusts around 60 mph were common in the Teton Range and east of the Continental Divide in central Wyoming ahead of the storm.
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 7, 2:52 AM MST, 7 hours 8 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 252 AM MST FRI DEC 7 2012 .SHORT TERM...FRIDAY THROUGH SUNDAY NIGHT IT LOOKS LIKE ANOTHER COMPLICATED AND ACTIVE WEATHER PATTERN FOR THE SHORT TERM SO WE WILL DIVIDE THE FORECAST INTO WEST OF THE DIVIDE AND EAST OF THE DIVIDE. WEST OF THE DIVIDE...THE SYSTEM THAT BROUGHT SOME LIGHT SNOW TO THE AREA HAS MOVED TO THE EAST WITH ONLY SOME LIGHT UPSLOPE SNOW IN SOME AREAS. HOWEVER...THE NEXT SYSTEM WILL BE CLOSE ON ITS HEELS AND IS NOW DROPPING THROUGH NORTHERN IDAHO AND WILL BEGIN TO PUSH INTO WESTERN WYOMING THIS AFTERNOON. THIS ONE LOOKS MUCH MORE IMPRESSIVE WITH A VERY STRONG JET TO WORK WITH WITH WINDS OF 125 KNOTS AT THE CORE. MUCH OF WESTERN WYOMING LOOKS TO BE IN THE FAVORED LEFT FRONT QUADRANT OF THE JET TONIGHT AND TOMORROW MORNING FOR SOME MID AND UPPER LEVEL DIVERGENCE. THERE IS NO QUESTION WITH PRECIPITATION TYPE WITH THIS SYSTEM WITH MUCH COLDER AIR IN PLACE SO ALMOST ALL PRECIPITATION WILL FALL AS SNOW. WITH THE COLD AIR IN PLACE SNOW RATIOS LOOK TO BE FAIRLY HIGH AS WELL. THE ONE LIMITING FACTOR WILL BE THE SYSTEM IS FAIRLY FAST MOVING SO NORTHWESTERN WYOMING LOOKS TO HAVE HEAVIER SNOW END BY MORNING AND ACROSS SOUTHWESTERN WYOMING SATURDAY MORNING. THERE WILL ALSO BE A FAIR AMOUNT OF WIND WITH THE SYSTEM AND WITH THE LIGHTER SNOW BLOWING AND DRIFTING SNOW WILL BE A PROBLEM AS WELL. WITH HIGH CONFIDENCE WE WILL GO AHEAD AND UPGRADE THE WINTER STORM WATCHES TO WARNINGS THIS MORNING. WE WILL ALSO POST WINTER WEATHER ADVISORIES FOR YELLOWSTONE PARK...THE ABSAROKAS AND JACKSON HOLE. WE DEBATED A WINTER STORM WARNING FOR THE JACKSON VALLEY BUT DECIDED TO GO WITH AN ADVISORY FOR NOW. HOWEVER...THERE COULD BE VERY ROUGH TRAVEL CONDITIONS NORTH OF JACKSON NEAR TETON PARK WHERE STRONG NORTHWEST WINDS MAY PRODUCE NEAR WHITE OUT CONDITIONS AT TIMES. FUTURE SHIFTS WILL HAVE TO WATCH THIS CLOSELY. ACCUMULATION AMOUNTS LOOKED REASONABLE SO FEW CHANGES WERE MADE. SNOW SHOULD TAPER OFF FOR MOST AREAS SATURDAY AFTERNOON BUT COLD CYCLONIC FLOW WILL KEEP SOME SNOW SHOWERS AROUND INTO SATURDAY NIGHT. SATURDAY NIGHT COULD BE ESPECIALLY CHILLY IF THERE IS ANY CLEARING WITH BELOW ZERO TEMPERATURES ACROSS THE WESTERN VALLEYS AND MUCH OF YELLOWSTONE. SUNDAY LOOKS TO HAVE A LULL IN ACTIVITY BEFORE THE NEXT SYSTEM APPROACHES FROM THE NORTHWEST SUNDAY NIGHT. MODELS ARE A BIT SLOWER SO WE TRIMMED BACK POPS A BIT FOR SUNDAY EVENING BUT UPPED THEM FOR SUNDAY NIGHT. EAST OF THE DIVIDE...AN SYSTEM AIDED BY A JET CORE IS NOW MOVING ACROSS NORTHERN WYOMING AND BRINGING SOME LIGHT SNOW TO AREAS MAINLY NORTH OF THE OWL CREEK RANGE. AMOUNTS ARE STILL EXPECTED TO REMAIN BELOW ADVISORY LEVEL ALTHOUGH AREAS IN NORTHERN JOHNSON COUNTY AND ALONG THE BORDER WITH MONTANA WILL LIKELY PICK UP A COUPLE OF INCHES. THIS SNOW SHOULD END THIS MORNING WITH MAINLY DRY WEATHER EXPECTED THE REST OF THE DAY. WINDS WILL BE GUSTY ACROSS THE FAVORED LOCATIONS IN THE SOUTHWESTERN WIND CORRIDOR BUT SHOULD REMAIN BELOW WARNING CRITERIA. THE COLD FRONT WILL DROP ACROSS THE AREA ON SATURDAY AND BRING GUSTY WINDS AS WELL AS FALLING TEMPERATURES. MODELS ARE STILL SPLIT ON HOW MUCH PRECIPITATION FALLS EAST OF THE DIVIDE THOUGH. WE WILL HAVE VERY COLD AIR ALOFT AND CYCLONIC FLOW OVER THE AREA BUT NOT A LOT OF MOISTURE TO WORK WITH. ALSO...THERE WILL BE STRONG DOWNSLOPING FLOW. FOR NOW...WE CUT BACK POPS JUST A BIT ON SATURDAY BUT KEPT AT LEAST CHANCE FOR MOST AREAS. WITH THE COLD AIR IN PLACE ANY SNOW THAT FALLS WILL BE HIGH RATIO BUT AMOUNTS LOOKS TO REMAIN BELOW ADVISORY LEVEL AT THIS TIME. SATURDAY NIGHT LOOKS TO BE VERY COLD WITH SINGLE DIGITS COMMONPLACE FOR MOST AREAS. SUNDAY WILL BE QUITE COLD AS WELL SO TEMPERATURES WERE KEPT CLOSE TO CONTINUITY. .LONG TERM...MONDAY THROUGH FRIDAY MODELS ARE CLOSE WITH A WEATHER SYSTEM MONDAY AND MONDAY NIGHT IN THE NW FLOW ALOFT. THIS SYSTEM DROPS SOUTH SOUTHEAST THROUGH THE AREA AND HANGS AROUND UNTIL MIDDAY TUESDAY BEFORE EXITING AROUND 00Z WED. BEST CHANCE OF SNOW WILL BE IN THE MOUNTAINS WITH SCATTERED AREAS OF LIGHT SNOW FOR THE LOWER ELEVATIONS. THIS SYSTEM WILL ALSO BRING ANOTHER SHOT OF COLD AIR TO THE AREA FOR TUESDAY. THERE IS SOME MODEL DIFFERENCES WED THROUGH FRI. THE GFS AND CANADIAN MODELS BRING THE NEXT SYSTEM INTO THE PAC NW WED AND BRING PRECIP INTO WESTERN WY WED PM AND WED NIGHT. THE ECMWF IS SLOWER AND MORE SPLIT WITH THIS SYSTEM WED PM/WED NIGHT...WHICH MEANS LESS PRECIP IN THE WEST. HAVE KEPT THE PRECIP CHANCE IN THE WEST WED AND WED NIGHT. FOR THE EAST MOSTLY DRY WED UNTIL LATE WED NIGHT WHEN A SLIGHT CHANCE OF PRECIP IS FORECAST. TEMPS A LITTLE WARMER ON WED. THE GFS HAS UNSETTLED WEATHER ON THURS WITH THE WEATHER SYSTEM MOVING THROUGH THE AREA. THE ECMWF HAS A WEAKER WEATHER SYSTEM MOVING THROUGH THE AREA THURS WHILE DIGGING THE SOUTHERN ENERGY INTO SOUTHERN CALIFORNIA. KEEPING THE BEST CHANCE OF SNOW IN THE MOUNTAINS WHILE THE LOWER ELEVATIONS WILL SEE SCATTERED AREAS OF LIGHT SNOW. COOLER HIGHS ON THURS. THEN NEXT FRI THE ECMWF IS MOSTLY DRY WHILE THE GFS BRING A WEAK DISTURBANCE INTO NW WY LATE IN THE DAY FRIDAY WITH PRECIP IN THE NW. FOR NOW LOW CHANCE OF PRECIP IN THE WEST AND MOSTLY DRY IN THE EAST. TEMPS A LITTLE MILDER NET FRI. && .AVIATION.../12Z ISSUANCE/ EAST OF THE CONTINENTAL DIVIDE... A WEAK COLD FRONT WILL SLOWLY PUSH SOUTH TO VCNTY KRIW-KCPR LINE BY 12Z. AREAS OF IFR/MVFR -SN...VCNTY AND NORTH OF A KCOD-KGEY-KBYG LINE...WILL GRADUALLY IMPROVE FROM THE WEST THOUGH 12Z...HOWEVER AREAS OF MVFR/LOCAL IFR CIGS WILL FILL IN BEHIND THE FRONT...AND THEN LIFT AND DISSIPATE 14Z-17Z. THE NEXT STRONGER STORM SYSTEM WILL BRING INCREASING WINDS ALOFT WITH AREAS OF LLWS DEVELOPING 00Z-06Z SAT ALONG THE LEE SLOPES OF THE DIVIDE...VCNTY KCOD-KLND...AND IN THE VCNTY OF THE BIGHORN MTNS. MTS WILL BECOME INCREASINGLY OBSCURED OVERNIGHT FRIDAY WITH AREAS OF MVFR/IFR -SN DEVELOPING VCNTY AND NORTH OF A KCOD-KBYG LINE BY 12Z SAT. WEST OF THE CONTINENTAL DIVIDE...A BRIEF PERIOD OF IMPROVEMENT WILL OCCUR THROUGH 18Z FRIDAY WITH MOST HIGHER MTNS REMAINING OBSCURED IN -SN. THE NEXT MORE POWERFUL PACIFIC STORM SYSTEM WILL SPREAD RAPIDLY DETERIORATING CONDITIONS IN SN/BLSN INTO NW WYOMING THIS AFTERNOON TO VCNTY KJAC BY 21Z. WIDESPREAD IFR/LIFR CONDITIONS IN SN/BLSN ARE EXPECTED WEST OF THE DIVIDE FRIDAY NIGHT WITH MTN TOP WINDS INCREASING TO NEAR 50KTS ALONG WITH AREAS OF LLWS. && .FIRE WEATHER... STRONG AND GUSTY SOUTHWEST WINDS WILL DEVELOP IN MOST AREAS TODAY IN ADVANCE OF A NEW STORM SYSTEM THAT WILL USHER IN SHARPLY COLDER CONDITIONS WITH SNOW OUT WEST AND SOME AREAS OF LIGHT SNOW EAST OF THE DIVIDE LATER FRIDAY NIGHT THROUGH SATURDAY NIGHT. GUSTY WINDS WILL CONTINUE INTO SATURDAY AS WELL. EXPECT LIGHTER WINDS ON SUNDAY. && .RIW WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO 11 AM MST SATURDAY WYZ001-002-013. WINTER STORM WARNING FROM 5 PM THIS AFTERNOON TO 5 PM MST SATURDAY WYZ023-024. WINTER STORM WARNING FROM 2 PM THIS AFTERNOON TO 11 AM MST SATURDAY WYZ012. && SHORT TERM...HATTINGS LONG TERM...AR AVIATION...AEM FIRE WEATHER...HATTINGS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 527 AM MST FRI DEC 7 2012 WYZ001>020-022>030-081300- 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- 527 AM MST FRI DEC 7 2012 ...WINTER STORM WARNING FOR THE TETONS FROM 2 PM TODAY UNTIL 11 AM SATURDAY... ...WINTER STORM WARNING FOR THE SALT AND WYOMING RANGES AND NEARBY STAR VALLEY FROM 5 PM FRIDAY TO 5 PM SATURDAY... ...WINTER WEATHER ADVISORY FOR YELLOWSTONE PARK...THE ABSAROKAS AND JACKSON HOLE FROM 2 PM TODAY UNTIL 11 AM SATURDAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT TODAY AND TONIGHT...SIGNIFICANT SNOWFALL AND WIND LIKELY...ACROSS THE WEST LATE THIS AFTERNOON AND TONIGHT. PLEASE SEE WINTER WEATHER PRODUCTS FOR DETAILS. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY SATURDAY...SNOW WILL CONTINUE IN WEST AND NORTHWEST WYOMING WITH WINDY CONDITIONS. TRAVEL MAY BE HAZARDOUS OVER MOUNTAIN PASSES DUE TO LOW VISIBILITY AND BLOWING AND DRIFTING SNOW. SUNDAY...COLD WITH HIGH TEMPERATURES 10 TO 20 DEGREES BELOW NORMAL. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ENCOURAGED TO REPORT SNOWFALL AMOUNTS OVER THE NEXT FEW DAYS. TEAM RIVERTON
The national radar mosaic for the moment the first event began.
3 winter storm, 1 high wind. Local standard time, as filed.
The Jackson Hole Ski Resort reported 12-15 inches of new snow.
The Snider Basin SNOTEL site reported 14 inches of snow. Other SNOTEL sites also received close to a foot of new snow.
A trained spotter reported 7 inches of snow 4.7 miles NE of Thayne.
The observing station at Camp Creek recorded wind gusts of 61 and 58 mph.
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, December 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: 416810, 416811, 416812, 417040.