Favorable southwest flow increased significantly over central Wyoming in advance of a powerful Pacific storm. The winds were strongest across Natrona County where sustained speeds of 40 mph with gusts over 65 mph were common Christmas Day.
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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.
Favorable southwest flow increased significantly over central Wyoming in advance of a powerful Pacific storm. The winds were strongest across Natrona County where sustained speeds of 40 mph with gusts over 65 mph were common Christmas Day. The wind ripped a portion of a roof from a house in southwest Casper and downed a power line in downtown Casper. At the Natrona County International Airport a peak wind speed of 68 mph was recorded at 0946 and 1049MST Christmas Day. A peak gust to 75 mph was clocked the same morning at Fales Rock RAWS.
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, 9:00 AM MST, 4 hours earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 900 AM MST WED DEC 24 2008 .UPDATE...STRONG GRADIENT CONTINUES TO DEVELOP ACROSS CENTRAL WYOMING. THIS WILL LEAD TO HIGH WINDS ACROSS THE GREEN MOUNTAINS AND NATRONA COUNTY OVERNIGHT INTO CHRISTMAS DAY. THE WINDS WILL LIKELY SLACKEN OVERNIGHT SOME TO SUB WARNING OVER NATRONA COUNTY...BUT WILL KEEP IT GOING TO EASE CONFUSION. SOUTHWEST WINDS OF 35 TO 50 MPH WILL BE COMMON WITH FREQUENT GUSTS OVER 60 MPH. .SHORT TERM...TODAY THROUGH FRIDAY NIGHT LOW CLOUDS AND SOME LIGHT SNOW CURRENTLY LOCATED ACROSS PORTIONS OF THE WESTERN BASINS THIS MORNING. OTHERWISE...GENERALLY DRY CONDITIONS ARE CURRENTLY PRESENT...AHEAD OF THE NEXT APPROACHING PACIFIC TROUGH. IR SATELLITE SHOWING ADDITIONAL CLOUD COVER ASSOCIATED WITH THIS PACIFIC TROUGH IS STREAMING INTO WESTERN IDAHO...WITH A PENDING ARRIVAL INTO WESTERN WYOMING DURING THE MORNING HOURS TODAY. LIGHT SNOW WILL BE FOUND TODAY ACROSS THE WEST...WITH SNOW COVERAGE INCREASING THROUGH THE AFTERNOON HOURS. THE BRUNT OF THE SYSTEM IS ANTICIPATED TO ARRIVE WEDNESDAY EVENING AND INTO THE OVERNIGHT HOURS. SNOWFALL RATES IN EXCESS OF AN INCH AN HOUR WILL BE FOUND ACROSS THE WESTERN MOUNTAINS AND VALLEYS DURING THE MORNING HOURS OF CHRISTMAS...WHICH SHOULD RESULT IN THE MAJORITY OF SNOWFALL ASSOCIATED WITH THIS STORM...ESPECIALLY WITH SOME INSTABILITY TO HELP BRING INTENSIFIED SNOWFALL ACROSS PORTIONS OF THE WEST. ISENTROPIC LIFT WILL ALSO PLAY A GOOD PART IN THE SNOWFALL OVER THE NEXT COUPLE OF DAYS. THE STRONGEST ISENTROPIC LIFT EXPECTED DURING THE EVENING HOURS TODAY AND WILL CONTINUE THROUGH THURSDAY MORNING. THE BRUNT OF THE SNOWFALL SHOULD FALL BEFORE THURSDAY EVENING...AND COVERAGE AND INTENSITY WILL WEAKEN ONCE THE INSTABILITY WEAKENS ALONG WITH THE ISENTROPIC LIFT THURSDAY EVENING. LIGHT SNOWFALL IS EXPECTED TO CONTINUE INTO THE OVERNIGHT HOURS AS THE TROUGH MOVES FURTHER EAST. BY THE TIME THE TROUGH AXIS MOVES FURTHER EAST...STORM TOTALS OF 12 TO 20 INCHES WILL BE POSSIBLE ACROSS THE WESTERN MOUNTAINS...WITH SOME AREAS OF THE WYOMING SALT RANGE EXPECTED TO SEE HIGHER AMOUNTS. STAR VALLEY IS ANTICIPATED TO SEE ANOTHER STORM TOTAL OF 10 TO 15 INCHES...AND JACKSON VALLEY WILL SEE 7 TO 10 INCHES...INCLUDING AROUND 8 INCHES IN THE TOWN OF JACKSON. LESSER AMOUNTS WILL BE FOUND IN THE ABSAROKA MOUNTAINS...AND UPPER GREEN RIVER BASIN WHERE ADVISORY AMOUNTS ARE ANTICIPATED. THE SOUTHWESTERN CORNER OF THE ABSAROKA MOUNTAINS FAVORED TO RECEIVE NEAR WARNING AMOUNTS OF 10 TO 14 INCHES...HOWEVER THESE AMOUNTS WILL BE LOCALIZED...AND SNOWFALL AMOUNTS OF 4 TO 7 INCHES WILL BE MORE COMMON ACROSS TRAVELED AREAS OF THE MOUNTAINS. THE WINTER STORM WATCH REMAINS IN EFFECT FOR THESE AREAS...WHICH ALLOWS THE UPCOMING SHIFT ONE LAST LOOK FOR SNOW TOTALS AND LAST CHECKS ON THE DEVELOPMENT OF THE SYSTEM AS IT MOVES FURTHER INLAND. AS OF NOW...ISSUANCE OF WARNINGS AND ADVISORIES ARE ANTICIPATED. ALONG WITH SNOW...STRONG WINDS ARE ANTICIPATED ACROSS THE WIND CORRIDOR BETWEEN ROCK SPRINGS AND CASPER. THESE INCREASED WINDS WILL DEVELOP THIS AFTERNOON...AND WILL CONTINUE OFF AND ON THROUGH CHRISTMAS DAY. THE MAIN LULL IN THESE STRONGER WINDS WILL OCCUR DURING THE OVERNIGHT HOURS BEFORE RETURNING DURING THE LATE MORNING AND AFTERNOON. AS THIS SYSTEM MOVES FURTHER EAST...THE BIG HORN BASIN...BIG HORN MOUNTAINS...AND NORTHERN JOHNSON COUNTY SHOULD AGAIN SEE AN INCREASED OPPORTUNITY FOR SNOWFALL. JOHNSON COUNTY AND THE MOUNTAINS WILL ESPECIALLY SEE THIS CHANCE DURING THURSDAY NIGHT AND INTO FRIDAY WHEN SNOWFALL WILL BE LIKELY. SNOWFALL AMOUNTS EXPECTED TO RANGE BETWEEN 2 AND 4 INCHES IN THE LOWER ELEVATIONS...WITH 4 TO 6 INCHES FOUND OVER THE BIG HORN MOUNTAINS. .LONG TERM...SATURDAY THROUGH WEDNESDAY GFS AND ECMWF BOTH AGREE THAT A STRONG W TO NW FLOW WILL DOMINATE THE MEDIUM RANGE PERIOD. THE RESULT WILL BE PERIODS OF SNOW WEST OF THE DIVIDE AND WINDY EAST OF THE DIVIDE. RIDGE FLATTENS SATURDAY BEHIND OUR BIG CHRISTMAS STORM ALLOWING THE FIRST GOOD SHOT OF SNOW OUT WEST ESPECIALLY BY SATURDAY NIGHT AND CONTINUING THROUGH SUNDAY. AFTER THAT...THE SNOW SPIGOT WILL BE HARD TO TURN OFF OUT WEST WITH SNOW OFF AND ON...MORE ON...THROUGH THE REMAINDER OF THE PERIOD. GENERAL LIGHT SNOW WILL PREVAIL WITH PERIODS OF MODERATE OR GREATER SNOW WITH EVERY PASSING DISTURBANCE WHICH WILL BE HARD TO TIME THIS FAR OUT. AREAS EAST OF THE DIVIDE SHOULD SEE PLENTY OF WIND... ESPECIALLY THE WIND CORRIDOR AND CODY FOOTHILLS BUT EVEN THE WIND RIVER BASIN WILL LIKELY MIX OUT IN FAVORABLE WNW TO NW MID LEVEL FLOW. TEMPERATURES WILL THUS BE TRICKY DEPENDING ON HOW MUCH WIND OCCURS VS THE BASIN INVERSIONS THAT WILL TRY TO STAY IN PLACE. HAVE PUT THE LEAST AMOUNT OF WIND IN THE BIG HORN BASIN ALONG WITH THE COOLEST TEMPS. IF THE HIGHS ERROR...IT WILL LIKELY STILL BE ON THE COOL SIDE...ESPECIALLY IF MORE AREAS SEE THE WIND OFF AND ON. H7 TEMPS VARY QUITE A BIT AT TIMES BETWEEN THE GFS AND THE EURO BUT ARE GENERALLY IN THE -4 TO -8C RANGE EAST OF THE DIVIDE WITH THE EXCEPTION OF A SHORTWAVE THAT THE MODELS HAVE PASSING BY TO THE NORTH EITHER TUESDAY...GFS...OR WEDNESDAY...ECMWF...WHEN H7 TEMPS DROP TO BELOW -10C ACROSS THE NORTH HALF. WESTERN VALLEY TEMPS WILL ALSO BE TRICKY AS MEX GUIDANCE IS GENERALLY IN THE SINGLE DIGITS EVERY NIGHT EVEN WITH SNOW FALLING. HAVE SIDED WITH WARMER TEMPS THAN GUIDANCE WITH PLENTY OF CLOUD COVER AND OFF AND ON SNOW...SIMILAR TO WHAT HAPPENED RECENTLY WITH RELATIVELY MILD OVERNIGHT LOWS IN JAC. && .AVIATION... A LEE SIDE SURFACE TROUGH WILL INTENSIFY ACROSS CENTRAL WYOMING TODAY WITH SOUTHWEST WIND INCREASING TO 30-35KT WITH GUSTS NEAR 50KT BTWN KRKS-KCPR. ALSO EXPECT AREAS OF LLWS FM VCNTY KCOD-KLND AFTER 18Z AS SW WINDS 7K-8KFT ASL INCREASE TO 30-40KTS OVER COLD AIR TRAPPED IN THE BASINS. CLOUD DECKS WILL GRADUALLY THICKEN LOWER OVER AND WEST OF THE DIVIDE THROUGH THE DAY WITH LIGHT SNOW AND MOUNTAIN OBSCURATIONS INCREASING THROUGH THE AFTERNOON. AFTER 00Z THURSDAY WIDESPREAD MVFR/AREAS OF IFR CONDITIONS ARE EXPECTED IN THE WEST WITH SNOWFALL RAPIDLY INCREASING OVERNIGHT. THE HEAVIEST SNOWFALL AND IFR/LIFR CONDITIONS ARE EXPECTED 06Z-18Z THURSDAY AFFECTING KJAC-KPNA-KBPI WITH POSSIBLE CLOSURES. && .FIRE WEATHER... THE NEXT PACIFIC TROUGH WITH ASSOCIATED HEAVY SNOWFALL WILL BEGIN TO MOVE INTO WESTERN WYOMING LATE THIS AFTERNOON AND INTO THE EVENING. SNOWFALL COVERAGE WILL INCREASE DURING THE OVERNIGHT HOURS...AND SNOWFALL RATES WILL INCREASE THROUGH THE MORNING HOURS. THIS SYSTEM IS ANTICIPATED TO BRING SIGNIFICANT SNOWFALL ACROSS THE WESTERN MOUNTAINS AND VALLEYS...SIMILAR TO THE STORM WHICH MOVED THROUGH LAST SUNDAY THROUGH TUESDAY. THE BRUNT OF SNOWFALL ACROSS THE WESTERN MOUNTAINS AND VALLEYS WILL OCCUR THROUGH THE LATE MORNING HOURS OF CHRISTMAS WITH LIGHTER SNOWFALL CONTINUING INTO THE EVENING HOURS. AHEAD OF THIS PACIFIC SYSTEM...WINDS ACROSS THE CORRIDOR BETWEEN ROCK SPRINGS AND CASPER WILL INCREASE THIS AFTERNOON...AND REMAIN ELEVATED THROUGH THE EVENING BEFORE EXPERIENCING A BRIEF LULL DURING THE OVERNIGHT HOURS. STRONG WINDS WILL AGAIN DEVELOP DURING THE AFTERNOON OF CHRISTMAS. SNOWFALL ASSOCIATED WITH THE TROUGH WILL SPREAD EAST OF THE DIVIDE ON THURSDAY...ESPECIALLY IMPACTING THE BIG HORN MOUNTAINS AND JOHNSON COUNTY. FOR FURTHER DETAILS REGARDING POTENTIAL HIGHLIGHTS FOR WINTER WEATHER AND HIGH WINDS...PLEASE SEE THE APPROPRIATE PRODUCTS...WSWRIW FOR WINTER WEATHER INFORMATION... AND NPWRIW FOR WIND INFORMATION. && .RIW WATCHES/WARNINGS/ADVISORIES... HIGH WIND WARNING THIS AFTERNOON THROUGH THURSDAY AFTERNOON FOR WYZ019-020. WINTER STORM WATCH FROM THIS EVENING THROUGH LATE THURSDAY NIGHT FOR WYZ001-002-012>015-023>027. && UPDATE...TWB SHORT TERM...BRANHAM LONG TERM...SKRBAC AVIATION...AEM FIRE WEATHER...BRANHAM
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 913 AM MST WED DEC 24 2008 WYZ001>020-022>030-251200- 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- 913 AM MST WED DEC 24 2008 ...WINTER STORM WATCHES FOR MOST OF WESTERN WYOMING 6 PM TODAY THROUGH CHRISTMAS NIGHT... ...HIGH WIND WARNING FOR EAST CENTRAL WYOMING INCLUDING CASPER THIS AFTERNOON THROUGH CHRISTMAS DAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT SNOWFALL WILL BECOME WIDESPREAD OVER WESTERN WYOMING BY THIS AFTERNOON AND WILL INTENSIFY TONIGHT. THIS SNOWFALL WILL CAUSE ROADWAYS...ESPECIALLY MOUNTAINS PASSES ACROSS WESTERN WYOMING TO BECOME SNOW PACKED AND SLICK. ADDITIONALLY...STRONG WINDS WILL BE FOUND OVER THE WIND CORRIDOR FROM THE GREEN MOUNTAINS TO CASPER. SOUTHWEST WINDS WILL INCREASE TO 35 TO 45 MPH...WITH GUSTS TO 60 MPH FROM THIS AFTERNOON THROUGH TONIGHT. THOSE TRAVELING ACROSS WESTERN WYOMING...OR IN HIGH PROFILE VEHICLES ACROSS EASTERN WYOMING WILL WANT TO CHECK CURRENT CONDITIONS AND FORECASTS BEFORE TRAVELING TODAY. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY SNOWFALL ACROSS WESTERN WYOMING WILL CONTINUE CHRISTMAS DAY AND INTO EARLY FRIDAY MORNING. THIS SYSTEM HAS THE POTENTIAL TO BRING SIGNIFICANT SNOWFALL ACROSS THE WESTERN MOUNTAINS AND VALLEYS. SNOWFALL OF 15 TO 25 INCHES IN THE MOUNTAINS IS LIKELY...WITH 2 TO 3 FEET POSSIBLE OVER THE SALT RIVER...WYOMING AND WESTERN WIND RIVER RANGES. THE WESTERN VALLEYS COULD RECEIVE 8 TO 15 INCHES. SOUTHWEST TO WEST WINDS ARE EXPECTED AS WELL PRODUCING BLOWING AND DRIFTING SNOW. SIGNIFICANT IMPACT TO TRAVEL OVER WESTERN WYOMING IS HIGHLY LIKELY. SEE WINTER STORM WATCH PRODUCT FOR MORE INFORMATION. STRONG SOUTHWEST WINDS ACROSS EAST CENTRAL WYOMING WILL CONTINUE THROUGH THURSDAY AFTERNOON. HIGH WIND...SUSTAINED WIND SPEEDS OF 40 MPH OR GREATER WITH GUSTS OF 60 MPH OR GREATER...ARE EXPECTED. SEE THE HIGH WIND WARNING PRODUCT FOR MORE INFORMATION. ANOTHER STORM SYSTEM WILL BRING YET ANOTHER ROUND OF SNOW TO THE FAR WEST OVER THE WEEKEND. HOLIDAY TRAVELLERS SHOULD CHECK THE LATEST FORECAST AND ROAD CONDITIONS BEFORE VENTURING OUT. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ENCOURAGED TO REPORT SNOWFALL AMOUNTS AND WIND SPEEDS TODAY. THANK YOU. TEAM RIVERTON
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 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: 142156, 142157.