A tight pressure gradient ahead of an approaching winter storm brought high wind to Natrona and southeast Fremont counties. A tractor-trailer was toppled in Casper by the high wind.
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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 tight pressure gradient ahead of an approaching winter storm brought high wind to Natrona and southeast Fremont counties. A tractor-trailer was toppled in Casper by the high wind.
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 28, 2:38 AM MST, 6 hours 32 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 238 AM MST TUE DEC 28 2010 .SHORT TERM...TODAY THROUGH THURSDAY NIGHT SIGNIFICANT WINTER STORM TO IMPACT THE CWA LATE TONIGHT THROUGH THE REMAINDER OF THE SHORT TERM. IT WILL BRING DECENT SNOWFALL TO THE WEST LATE TONIGHT INTO WEDNESDAY NIGHT...THEN TO AREAS EAST OF THE DIVIDE TO FAVORED UPSLOPE AREAS EARLY THURSDAY MORNING THROUGH THURSDAY NIGHT. VERY COLD AIR WILL MOVE IN AS WELL. STORM SYSTEM MOVING THROUGH THE ALEUTIANS THIS MORNING AND WILL RAPIDLY DRIVE SOUTHEAST TODAY...MOVING ONSHORE EARLY THIS EVENING. IT SPINS UP INTO A CLOSED LOW AS IT MOVES INTO THE CENTRAL GREAT BASIN WEDNESDAY NIGHT/THURSDAY MORNING. IT THEN BEGINS TO LIFT NORTHEAST ACROSS THE CENTRAL ROCKIES INTO SE WY AND NE CO BY 12Z FRIDAY...WITH PRECIPITATION WINDING DOWN. WARM AIR PRECEDES THE SYSTEM WITH TEMPERATURES IN THE 30S AND LOWER 40S EAST OF THE DIVIDE...WITH 20S TO LOWER 30S OVER THE WEST. GUSTY SOUTHWEST TO WEST WINDS WILL BE COMMON TODAY OVER THE EAST SLOPES OF THE WIND RIVERS AND ABSAROKAS AS WELL AS ADJACENT BASIN LOCATIONS. THE UPPER WIND RIVER BASIN AND CENTRAL WIND CORRIDOR WILL ALSO GET GOING AS WELL. WILL SEE WEAK ISENTROPIC LIFT OVER THE NORTHWEST TODAY AND THIS EVENING WITH SOME LIGHT SNOW/FLURRIES FALLING THERE WITH LOCALLY AN INCH OR TWO. MOISTURE INCREASES THIS EVENING AS WELL AS THE SYSTEM APPROACHES. SW-NE ORIENTED JET STREAK MOVES INTO THE WEST AFTER 06Z WEDNESDAY WITH WIDESPREAD SNOW DEVELOPING OVER MUCH OF FAR WESTERN WYOMING...SPREADING ACROSS THE REMAINDER OF THE WEST THROUGH 12Z. THE JET SLOWLY SHIFTS EAST DURING THE DAY WEDNESDAY...WITH THE SNOW WINDING DOWN DURING THE EVENING. MAINLY LIGHT SNOW WILL PERSIST OVERNIGHT AS UPPER DYNAMICS SHIFT SOUTH AND EAST. HAVE ISSUED WINTER STORM WATCHES FOR THE TETONS...SALTS AND THE STAR VALLEY WHICH SHOULD SEE THE BEST SNOWFALL THERE FROM MIDNIGHT WEDNESDAY THROUGH MIDNIGHT THURSDAY. 12-18 INCHES IS LIKELY IN THE SALTS WITH AROUND 12 INCHES IN THE TETONS...WITH 5 TO 8 INCHES IN THE STAR VALLEY. OTHER AREAS WILL LIKELY BE IN NEED OF ADVISORIES. COLD FRONT DRIVES SOUTH ACROSS WYOMING LATE WEDNESDAY AFTERNOON OVERNIGHT INTO THURSDAY MORNING. THE ACTION SHIFTS EAST OF THE DIVIDE AS SNOW DEVELOPS IN THE FAVORED UPSLOPE AREAS BEHIND THE FRONT...WHICH CONTINUES TO FALL THROUGH THURSDAY...TAPERING TO LIGHT SNOW/FLURRIES THURSDAY NIGHT. VERY COLD AIR MOVES IN BEHIND THE FRONT WITH SOME HIGH SNOW RATIOS OF 20:1 TO 25:1 EXPECTED. THOSE AREAS ALONG THE EASTERN ABSAROKAS...OWL CREEKS...EASTERN WIND RIVERS...GREEN MOUNTAINS...CASPER MOUNTAIN AND SOUTHERN BIGHORNS AND ADJACENT LOWER ELEVATIONS WILL LIKELY SEE SIGNIFICANT SNOW...ALBEIT LOW MOISTURE CONTENT FLUFF. WATCHES WILL LIKELY BE NEEDED FOR THESE AREAS. TEMPERATURES FALL INTO THE SINGLE DIGITS TO MID TEENS FOR HIGHS THURSDAY...WITH WIDESPREAD SUB ZERO OVERNIGHT LOWS FRIDAY MORNING. LONG TERM...FRIDAY THROUGH TUESDAY WINTER STORM WILL LIKELY STILL BE IMPACTING OUR ERN AND SRN ZONES THROUGH FRIDAY WITH BITTER COLD TEMPS...BREEZY TO LOCALLY WINDY AREAS AND AT LEAST LIGHT SNOWFALL. HAVE BUMPED UP POPS INTO THE HIGH CHANCE RANGE IN THE LOWER ELEVATIONS AND LIKELY IN THE MTNS. WE WILL LIKELY NEED TO HIT THESE HARDER IN THE SHORT TERM...ESPECIALLY WITH THE SLOWER ECMWF AND EVEN SLOWER YET NAM. GFS SEEMED ODD TONIGHT WITH FRACTURED LOOK AND DID NOT MATCH THE OVERALL MODEL OF WHAT A CLASSIC CLOSING OFF LOW SHOULD LOOK LIKE. THE ECMWF...NAM AND EVEN THE GEM MATCHED MUCH CLOSER WHAT THIS STORM SHOULD END UP LOOKING LIKE. OVERALL PATTERN HAS CHANGED LITTLE SINCE WE STARTED FOLLOWING THIS THE MIDDLE OF LAST WEEK. THIS STORM ORIGINATED IN THE POLAR REGIONS AND THE CENTRAL PACIFIC STORM SYSTEM WILL PUMP UP THE RIDGE ON THE BACKSIDE ALLOWING THIS STORM TO DIG QUICKLY INTO THE GREAT BASIN WEDNESDAY NIGHT BEFORE STALLING OUT OVER UT ON THURSDAY. THE SYSTEM WILL THEN LIKELY LIFT NE POSSIBLY BECOME MORE DISORGANIZED AS MANY INTENSE UPPER LOWS DO AFTER 18-24 HOURS. BITTER COLD AIR WILL THEN BECOME ENTRENCHED OVER THE AREA FOR A COUPLE DAYS WITH THE SNOW COVERED BASINS AND VALLEYS BECOMING BITTER COLD. COULD SEE 15 TO 25 BELOW ZERO EAST OF THE DIVIDE AND 25 TO 35 BELOW WEST OF THE DIVIDE. WINDS WILL TURN QUICKLY TO THE SW IN THE WIND CORRIDOR BY SATURDAY WITH A RAW DAY IN STORE FROM NE SWEETWATER COUNTY OVER TO CPR AND THE LEE OF THE MTN RANGES LIKE THE EAST SLOPE OF THE ABSAROKAS. MODELS DIFFER ON THE NEXT SHORTWAVE COMING DOWN WITH THE ECMWF HOLDING OFF UNTIL MONDAY AND THE GFS SHOWING SUNDAY. USUALLY...THESE SHORTWAVES FOLLOW WITHIN 48 HOURS SO WE WILL NEED TO WATCH THIS. THE GFS IS ALSO MUCH WETTER WITH A MOIST ISENTROPIC UPGLIDE PATTERN EARLY NEXT WEEK THAT THE ECMWF REALLY DOESN'T SHOW. THE END OF THE YEAR WILL DEFINITELY GO OUT ON A BITTER COLD NOTE WITH ALL THE EXPECTED FRESH SNOW COVER AND -20C H7 AIR OR COLDER THROUGH FRI NIGHT. && .AVIATION... WEST-NORTHWEST FLOW WILL BRING INCREASING MOISTURE TO AREAS WEST OF THE DIVIDE LATE THIS MORNING AND THIS AFTERNOON. BY 00Z/WED...MVFR CONDITIONS AT KJAC AND THE FAR WEST VALLEYS. LOWERING CEILINGS ANTICIPATED AT KBPI AND KPNA AFTER THIS TIME...WITH MVFR POSSIBLE LATE IN THE FORECAST PERIOD AT KPNA. BETTER CHANCE FOR LOWERING VISIBILITY AND CEILINGS IN -SN AFTER 06Z/WED...ESPECIALLY AT KJAC. TO THE EAST...VFR CONDITIONS TO PREVAIL. THE MAIN HAZARD WILL BE GUSTY SURFACE WIND AT KCPR WHERE SOUTHWEST WIND 25-35KTS WILL BE COMMON DURING THE DAYLIGHT HOURS. WIDESPREAD MOUNTAIN TOP OBSCURATIONS LIKELY ALONG AND WEST OF THE DIVIDE BY 18Z/TUE. SAME AREA TO BE THE MOST PRONE FOR ICING AFTER ABOUT 15Z/TUE. && .FIRE WEATHER... A SIGNIFICANT STORM SYSTEM WILL IMPACT THE REGION TONIGHT THROUGH THURSDAY NIGHT. GUSTY SOUTHWEST TO WEST WINDS ARE EXPECTED TODAY IN THE USUAL PLACES. WIDESPREAD SNOW WILL DEVELOP IN THE WEST TONIGHT AND CONTINUE HEAVY AT TIMES THROUGH WEDNESDAY EVENING...BEFORE TAPERING TO LIGHT SNOW/FLURRIES. A STRONG COLD FRONT WILL MOVE THROUGH THE DISTRICT WEDNESDAY NIGHT BRINGING SIGNIFICANT SNOW TO AREAS EAST OF THE DIVIDE AS WELL. VERY COLD AIR MOVES IN BEHIND THE FRONT. && .RIW WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY EVENING WYZ012-023-024. && SHORT TERM...TWB LONG TERM...SKRBAC AVIATION...CNJ FIRE WEATHER...TWB
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 500 AM MST TUE DEC 28 2010 WYZ001>020-022>030-291200- 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 TUE DEC 28 2010 ...WINTER STORM WATCHES FOR PORTIONS OF WESTERN WYOMING LATE TONIGHT THROUGH WEDNESDAY EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT A SIGNIFICANT STORM SYSTEM WILL MOVE INTO THE GREAT BASIN TONIGHT... WITH SIGNIFICANT MODERATE TO POSSIBLY HEAVY SNOW DEVELOPING OVER FAR WESTERN WYOMING AROUND MIDNIGHT. THE SNOW IS EXPECTED TO CONTINUE INTO WEDNESDAY THERE. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THE SNOW WILL CONTINUE OVER WESTERN WYOMING THROUGH WEDNESDAY EVENING BEFORE TAPERING TO LIGHT SNOW. SNOWFALL OF A FOOT OR MORE IS POSSIBLE IN THE TETONS AND THE SALT RIVER RANGE...WITH A HALF FOOT OR BETTER IN THE STAR VALLEY. LESSER AMOUNTS ARE POSSIBLE ELSEWHERE ACROSS WESTERN WYOMING. SOUTHWEST WINDS WILL CAUSE SOME BLOWING AND DRIFTING SNOW. A LARGE UPPER LOW WILL THEN DEVELOP OVER UTAH WEDNESDAY NIGHT INTO THURSDAY. AT THE SAME TIME...A STRONG COLD FRONT WILL MOVE SOUTH OUT OF MONTANA WEDNESDAY NIGHT SHIFTING THE SNOW TO AREAS EAST OF THE DIVIDE AND OVER SWEETWATER COUNTY. THE SNOW...POSSIBLY HEAVY AT TIMES...WILL CONTINUE THROUGH THURSDAY EVENING BEFORE TAPERING TO LIGHT SNOW OR FLURRIES. SIGNIFICANT SNOWFALL IN EXCESS OF 6 INCHES IS QUITE POSSIBLE IN THE FAVORED UPSLOPE AREAS...ESPECIALLY LANDER...RIVERTON...CASPER AND THERMOPOLIS. HEAVY SNOW IS ALSO AS FAR SOUTH AS SWEETWATER COUNTY. NORTH TO NORTHEAST WINDS IN THESE AREAS WILL CAUSE AREAS OF BLOWING AND DRIFTING SNOW. THE COLDEST AIR OF THE SEASON WILL MOVE IN BEHIND THIS STORM SYSTEM. HIGHS THURSDAY WILL LIKELY BE DROPPING DURING THE DAY IN MOST AREAS WITH ONLY SINGLE DIGITS EXPECTED THURSDAY AFTERNOON. BY FRIDAY MORNING...LOWS WILL BE 5 TO 15 BELOW EAST OF THE DIVIDE AND 15 TO 25 BELOW WEST OF THE DIVIDE. THE WESTERN AND CENTRAL BASINS AND VALLEYS WILL BE COLDER STILL ON SATURDAY MORNING WITH 10 TO 20 BELOW ZERO COMMON IN THE WIND RIVER AND BIGHORN BASINS AND 20 TO 30 BELOW ZERO WEST OF THE DIVIDE. TRAVEL WILL BE IMPACTED OVER THE WEST FROM TONIGHT THROUGH WEDNESDAY NIGHT AND FROM WEDNESDAY NIGHT THROUGH AT LEAST THURSDAY NIGHT OR FRIDAY MORNING EAST OF THE DIVIDE. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ASKED TO REPORT SNOWFALL OVER WESTERN WYOMING TONIGHT. THANK YOU. TEAM RIVERTON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 522 AM MST TUE DEC 28 2010 WYZ001>020-022>030-282300- 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- 522 AM MST TUE DEC 28 2010 ...WINTER STORM HEADING FOR THE COWBOY STATE ALONG WITH BITTER COLD TEMPERATURES... A DEVELOPING STORM SYSTEM ALONG THE PACIFIC COAST WILL STRENGTHEN AND MOVE SOUTHEAST INTO UTAH BY WEDNESDAY NIGHT. THE STORM WILL MOVE VERY LITTLE THURSDAY BEFORE TRACKING ACROSS CENTRAL COLORADO THURSDAY NIGHT AND THEN OFF INTO THE WESTERN HIGH PLAINS ON FRIDAY. THIS EXPECTED STORM TRACK IS FAVORABLE FOR HEAVY SNOW ACROSS THE SOUTHERN TWO-THIRDS OF THE AREA. THE STORM WILL IMPACT WESTERN WYOMING STARTING TONIGHT WITH THE HEART OF THE STORM IMPACTING THE WEST WEDNESDAY INTO WEDNESDAY EVENING. THE WEST WILL SEE DECREASING SNOW ON THURSDAY. AS THE STORM STRENGTHENS OVER CENTRAL UTAH WEDNESDAY NIGHT AND THURSDAY...SNOW WILL DEVELOP EAST OF THE CONTINENTAL DIVIDE AND ACROSS THE SOUTH. IT APPEARS THIS AREA WILL SEE THE WORST OF THE STORM ON THURSDAY INTO THURSDAY NIGHT. THE SNOW WILL TAPER OFF EAST OF THE DIVIDE ON FRIDAY AFTERNOON AS THE STORM HEADS INTO THE PLAINS. EARLY INDICATIONS POINT TO THE POTENTIAL FOR MORE THAN 6 INCHES OF SNOW FOR LANDER...RIVERTON...CASPER AND THERMOPOLIS. SWEETWATER COUNTY...INCLUDING ROCK SPRINGS MAY ALSO SEE AROUND 6 INCHES. HEAVIER SNOW IN EXCESS OF A FOOT IS POSSIBLE NEAR THE EAST SLOPE OF THE MOUNTAINS...INCLUDING ABOVE LANDER AND ON CASPER MOUNTAIN. IN ADDITION TO THE SNOW...ARCTIC AIR WILL BE PLUNGING SOUTH INTO WYOMING THURSDAY THROUGH FRIDAY. A NORTH TO NORTHEAST WIND OF 15 TO 30 MPH WITH HIGHER GUSTS WILL USHER IN THE BITTER COLD AIR THURSDAY. THERE WILL BE AREAS OF BLOWING AND DRIFTING SNOW WHICH WILL MAKE TRAVEL HAZARDOUS. FORECAST HIGH TEMPERATURES ON FRIDAY WILL ONLY BE IN THE SINGLE DIGITS WITH MANY MOUNTAIN LOCATIONS REMAINING BELOW ZERO. LOWS THURSDAY NIGHT WILL DROP TO BETWEEN 5 AND 15 DEGREES BELOW ZERO EAST OF THE DIVIDE WITH 15 TO 25 BELOW ZERO WEST OF THE DIVIDE. BY SATURDAY MORNING...TEMPERATURES ARE EXPECTED TO PLUMMET TO BETWEEN 10 AND 20 BELOW ZERO IN THE WIND RIVER AND BIGHORN BASINS WITH 20 TO 30 BELOW ACROSS THE WESTERN VALLEYS AND BASINS. HOLIDAY TRAVELERS AND RESIDENTS SHOULD BEGIN PREPARATIONS FOR THIS UPCOMING WINTER STORM. A MAJOR IMPACT TO TRAVEL WILL LIKELY OCCUR WITH THIS STORM...BEGINNING IN THE WEST LATE TONIGHT THROUGH WEDNESDAY...AND THEN OVER MUCH OF THE REGION THURSDAY THROUGH FRIDAY MORNING. SKRBAC
The national radar mosaic for the moment the first event began.
2 high wind. Local standard time, as filed.
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: 270235, 270238.