The first in a series of strong Pacific storm systems slammed western Wyoming with one to two feet of mountain snow. Snowfall in the Jackson and Star valleys commonly ranged from 10 to 18 inches.
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.
The first in a series of strong Pacific storm systems slammed western Wyoming with one to two feet of mountain snow. Snowfall in the Jackson and Star valleys commonly ranged from 10 to 18 inches. Some notable totals were 25 inches at Snow King Ski Area and nearly 18 inches just southeast of Thayne.
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 21, 3:13 PM MST, 2 hours 47 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 313 PM MST SUN DEC 21 2008 .SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT A PACIFIC STORM OVER THE PACIFIC NORTHWEST MOVING INTO IDAHO WILL MOVE EAST THROUGH THE NIGHT. LIGHT SNOWFALL WAS ALREADY FALLING OVER MUCH OF THE WESTERN MOUNTAINS. AREAS OF HEAVIER SNOWFALL OVER IDAHO AND NORTHERN UTAH WILL MOVE EAST THIS EVENING. WINTER STORM WARNINGS ARE IN EFFECT FOR THE WESTERN MOUNTAINS AND VALLEYS TONIGHT AND MONDAY. WINTER WEATHER ADVISORIES ARE IN EFFECT FARTHER TO THE EAST ACROSS THE WIND RIVER MOUNTAINS AND THE ABSAROKA MOUNTAINS...WHERE 5 TO 10 INCHES OF SNOW IS EXPECTED... AS WELL AS THE UPPER GREEN RIVER BASIN WHERE 3 TO 6 INCHES ARE EXPECTED. SNOWFALL OF 10 TO 18 INCHES ARE EXPECTED IN THE TETON MOUNTAINS WITH 5 TO 10 INCHES IN THE VALLEYS. 8 TO 15 INCHES OF SNOW IS EXPECTED ACROSS YELLOWSTONE NATIONAL PARK AS WELL AS THE WYOMING AND SALT RANGES. A COLD FRONT WILL PASS THROUGH MONDAY AFTERNOON. BEHIND THE COLD FRONT...THE SNOWFALL AMOUNTS ARE EXPECTED TO DECREASE WITH SOME LIGHT SNOWFALL INTO MONDAY NIGHT. THE COLD FRONT WILL BRING A CHANCE OF SNOW EAST OF THE CONTINENTAL DIVIDE MONDAY NIGHT AND TUESDAY. IN THE SHORT TERM TEMPERATURES WILL RISE WITH THE INCOMING STORM SYSTEM. THE COLD FRONT WILL MOVE SOUTH ACROSS THE EAST TUESDAY INTO CENTRAL WYOMING THEN MOVE SOUTH TUESDAY NIGHT WITH A RETURN TO COLDER TEMPERATURES FOR TUESDAY NIGHT. MODELS IN FAIRLY GOOD AGREEMENT THROUGH THE SHORT TERM. AS SNOW SHIFTS EAST SNOWFALL WILL PICK UP IN THE BIGHORN MOUNTAINS WITH POTENTIAL ADVISORY AMOUNTS THERE ON MONDAY AFTERNOON AND MONDAY NIGHT. .LONG TERM...WEDNESDAY THROUGH SATURDAY GOOD OVERALL RUN TO RUN MODEL CONSISTENCY EARLY THIS MORNING WITH GLOBAL MODEL SOLUTIONS LOCKED ON TO PROGRESSIVE SHORT-WAVE TROUGHS MOVING THROUGH THE QUASI-PERMANENT LONG-WAVE TROUGH OVER THE WESTERN U.S. BOTH GFS AND ECMWF SOMEWHAT WEAKER AND SLOWER REGARDING THE WARM ADVECTION AHEAD OF A SHORT-WAVE TROUGH MOVING THROUGH SOUTHERN CALIFORNIA CHRISTMAS EVE. SLOWED THE ONSET AND DECREASED SNOW CHANCES SOMEWHAT FOR THE ISENTROPIC ASCENT SNOWFALL EXPECTED OVER THE WEST ON CHRISTMAS EVE. THE WIDESPREAD WARM ADVECTIVE SNOWFALL EVENT STILL GETS WELL UNDERWAY BY CHRISTMAS MORNING AS A MUCH STRONGER NORTHERN SHORT- WAVE TROUGH BEGINS TO DIG INTO THE INLAND NORTHWEST. EXCELLENT CHANCES FOR A TRUE WHITE CHRISTMAS CONTINUE FOR MOST LOCATIONS ALONG AND WEST OF THE DIVIDE. STRONG FRONTOGENETIC FORCING PROGGED OVER SWEETWATER COUNTY CHRISTMAS DAY AS THE MAIN PORTION OF THE TROUGH DIGS SOUTHWARD THROUGH THE WESTERN GREAT BASIN. THE TROUGH ORIENTATION AND TRAJECTORY SHOULD RESULT IN GOOD TO EXCELLENT SNOW CHANCES ON CHRISTMAS FOR SWEETWATER COUNTY...TYPICALLY IMPACTED BY DOWNSLOPING EFFECTS. THE BASINS EAST OF THE DIVIDE WILL REMAIN MAINLY DRY AS STRONG DOWNSLOPING WESTERLY FLOW WRINGS OUT MOISTURE. MAIN AREA OF ATMOSPHERIC ASCENT DUE TO JET DYNAMICS AND QG FORCING MOVE DUE SOUTH INTO ARIZONA AND NEW MEXICO BY FRIDAY MORNING. VERY COLD CONDITIONS EXPECTED STATEWIDE FRIDAY WITH ISOLATED LIGHT SNOW SHOWERS EXPECTED OVER THE SOUTH. OPERATIONAL GFS AND ECMWF IN EXCEPTIONAL AGREEMENT NEXT WEEKEND WITH A WARM AND MOIST NEAR ZONAL FLOW DEVELOPING OVER THE PACIFIC NORTHWEST AND NORTHERN ROCKIES. AT LEAST A BRIEF BREAK IN BETWEEN TROUGHS IS BECOMING MORE LIKELY AS AN OMEGA BLOCK DEVELOPS OVER SIBERIA AND THE CURRENT UPPER LEVEL FLOW PATTERN SHIFTS FARTHER WEST. && .AVIATION... STRONG PACIFIC STORM SYSTEM WILL MOVE EASTWARD INTO THE PACIFIC NORTHWEST TONIGHT AND INTO NORTHERN IDAHO/WESTERN MONTANA BY MONDAY EVENING. WEST FLOW AND INCREASING PACIFIC MOISTURE WILL BRING OVERRUNNING LIGHT TO MODERATE SNOW TO WESTERN WYOMING TONIGHT THROUGH MONDAY EVENING. MVFR CONDITIONS AT KJAC...KBPI AND KPNA WILL PREVAIL THIS EVENING AND THEN DETERIORATE TO IFR AFTER MIDNIGHT AND PERSIST THROUGH EARLY MONDAY EVENING. MOUNTAIN OBSCURATIONS ARE EXPECTED TONIGHT THROUGH MONDAY EVENING. VFR CONDITIONS AND LIGHT WINDS WILL PREVAIL AT MOST LOCATIONS EAST OF THE DIVIDE TONIGHT. THE EXCEPTION WILL BE AT KCPR...WHERE SOUTH WINDS WILL GUST TO 25 KT WITH SURFACE LOW PRESSURE DEVELOPING IN NORTHWESTERN MONTANA. AS THE UPPER LOW MOVES EASTWARD MONDAY...SNOW WILL MOVE INTO SOUTHWESTERN WY WITH KRKS BECOMING MVFR/IFR IN LIGHT SNOW AFTER 13Z. AS SURFACE LOW MOVES ACROSS EASTERN WY MONDAY...WINDS AT KCPR WILL SHIFT TO THE SOUTH SOUTHWEST WITH GUSTS TO NEAR 40 KT. A COLD FRONT WILL MOVE INTO THE BIGHORN BASIN MONDAY AFTERNOON WITH A WIND SHIFT TO THE NORTHWEST AT KCOD AT AROUND 20Z AND A WIND SHIFT TO THE NORTH AT KWRL AT 21Z. && .FIRE WEATHER...TEMPERATURES WILL REMAIN COLD WITH HIGH HUMIDITY. THE WEST IS EXPECTED TO RECEIVE PERIODS OF SNOW THROUGH MONDAY WITH LOCAL AMOUNTS NEAR 18 INCHES IN THE TETONS. MIXING HEIGHTS WILL BE LOW WITH LOW CLOUDS AND SNOWFALL. THE SOUTH WILL BE BREEZY TO WINDY. && .RIW WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 5 PM MST MONDAY FOR WYZ002-014>016- 026. WINTER STORM WARNING UNTIL 5 PM MST MONDAY FOR WYZ001-012-013- 023>025-027. && SHORT TERM...C.BAKER LONG TERM...CHURCH AVIATION...SMITH FIRE WEATHER...C.BAKER
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 312 PM MST SUN DEC 21 2008 WYZ001>020-022>030-221300- 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- 312 PM MST SUN DEC 21 2008 ...WINTER STORM WARNINGS AND WINTER WEATHER ADVISORIES FOR WESTERN WYOMING THIS AFTERNOON THROUGH MONDAY AFTERNOON... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...THIS AFTERNOON AND TONIGHT SIGNIFICANT SNOWFALL WILL RETURN TO THE WESTERN MOUNTAINS AND VALLEYS LATE THIS AFTERNOON. SNOWFALL IS EXPECTED TO BEGIN DURING THE LATE AFTERNOON HOURS...AND WILL CONTINUE TONIGHT AND INTO MONDAY AFTERNOON. SNOWFALL MAY BE HEAVY AT TIMES...AND WILL CAUSE SLICK AND DIFFICULT TRAVEL OVER THE WESTERN MOUNTAIN PASSES. MOTORISTS ARE ENCOURAGED TO CHECK CURRENT CONDITIONS AND WINTER WEATHER PRODUCTS BEFORE TRAVELING. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY SNOWFALL WILL CONTINUE THROUGH MONDAY AFTERNOON. TOTAL ACCUMULATION OF 10 TO 18 INCHES OF SNOW IS EXPECTED IN THE WESTERN MOUNTAINS WITH 5 TO 10 INCHES OF SNOW IN THE WESTERN VALLEYS BY MONDAY AFTERNOON. THE SNOW WILL SPREAD INTO NORTH-CENTRAL AND NORTHEAST WYOMING MONDAY NIGHT. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ENCOURAGED TO REPORT SNOWFALL AMOUNTS THIS AFTERNOON AND TONIGHT. THANK YOU. TEAM RIVERTON
The national radar mosaic for the moment the first event began.
6 winter storm. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2008Every state in 2008This day in weather historyWarnings in Wyoming, December 2008
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: 142170, 142171, 142172, 142173, 142174, 142169.