Strong westerly flow produced high wind over Chief Joseph Pass where sustained wind was measured between 50 and 70 mph along State Highway 296.
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The episode as NWS RIW wrote it up.
Strong westerly flow produced high wind over Chief Joseph Pass where sustained wind was measured between 50 and 70 mph along State Highway 296.
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 23, 2:50 AM MST, 55 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 250 AM MST SUN DEC 23 2007 .SHORT TERM...TODAY THROUGH TUESDAY NIGHT AREAS OF LIGHT SNOW BEGINNING TO DEVELOP EARLY THIS MORNING AS SHORT-WAVE DROPS INTO WESTERN WYOMING FROM THE NORTHWEST. MOISTURE QUITE LIMITED WITH THIS FEATURE AND NOT EXPECTING MUCH SNOWFALL AFTER SUNRISE. THE ONE EXCEPTION WILL BE 1 TO 3 INCH AMOUNTS OVER SOUTHERN NATRONA COUNTY WHERE LIFT AND MOISTURE COMBINE TO PRODUCE AN AREA OF MODERATE SNOWFALL DURING THE MORNING HOURS. LOWERED PRECIP CHANCES MOST AREAS FOR TODAY AS LATEST UPSTREAM OBSERVATIONS AND THE 00Z GFS DRIER IN THE UNSTABLE LAYER JUST NEAR H7 TODAY. COULD NOT RULE OUT SNOW SHOWER DEVELOPMENT ALL TOGETHER THOUGH WITH A 140 KT DUE NORTHERLY JET POISED OVER THE WESTERN HALF OF THE STATE AROUND MID-DAY. ATTENTION QUICKLY TURNS TO THE NEXT UPSTREAM TROUGH WHICH IS EXPECTED TO BRING ANOTHER ROUND OF SIGNIFICANT SNOW TO THE WESTERN MOUNTAINS BEGINNING TONIGHT AND CONTINUING THROUGH CHRISTMAS EVE. LATEST GFS AND ECMWF SIMILAR WITH THE UPPER LEVEL PATH AND THE RESULTING SURFACE SNOWFALL. DECIDED ON A WINTER STORM WATCH FOR THE WESTERN MOUNTAIN ZONES...EXCLUDING YELLOWSTONE PARK FOR TONIGHT THROUGH MONDAY EVENING. WIDESPREAD 12-16 INCH AMOUNTS EXPECTED IN THE HIGHER TERRAIN WITH 4-8 INCHES IN THE JACKSON AND STAR VALLEYS. ISENTROPIC UPGLIDE BEGINS TO COMMENCE OVER THE WEST TONIGHT CONTINUING THROUGH FORENOON MONDAY BEFORE A STRONG COLD FRONT PLOWS THROUGH THIS AREA MONDAY AFTERNOON. GOOD JET LIFT/DYNAMICS ALONG WITH STRONG OROGRAPHICS AND A GOOD VERTICAL TEMPERATURE PROFILE FOR LIGHT FLUFFY POWDER. STRONG FRONTOGENESIS TAKES PLACES OVER THE NORTH MONDAY AFTERNOON WITH A STRONG COLD FRONT BLASTING SOUTHWARD EAST OF THE DIVIDE DURING THE EVENING. INCREASED PRECIP CHANCES FOR MAY AREAS ALONG AND EAST OF THE DIVIDE WITH THE GFS HINTING AT AN ORGANIZED MID-LEVEL CIRCULATION OVERCOMING ANY DOWNSLOPING EFFECTS MOVING THROUGH AND PRODUCING BANDS OR AN AREA OF SNOW...SIMILAR TO THURSDAY EVENINGS OCCURRENCE. MOST LOCATIONS IN THE COUNTY WARNING AREA EXPECTED TO RECEIVED AT LEAST SOME SNOWFALL ON MONDAY MAKING FOR A PICTURESQUE CHRISTMAS DAY. TRAVELERS...HOWEVER...WILL LIKELY EXPERIENCE DELAYS WITH SNOW COVERED ROADWAYS. MODERATE TO STRONG SOUTHWEST WINDS WILL ACCOMPANY THIS SYSTEM...CREATING AREAS OF BLOWING AND DRIFTING SNOW AND POOR VISIBILITIES MONDAY AND MONDAY NIGHT. CHRISTMAS DAY IS EXPECTED TO BE BREEZY AND COLD WITH AREAS OF BLOWING AND DRIFTING SNOW CONTINUING IN THE WIND CORRIDOR FROM THE RED DESERT EAST TO CASPER AS H7 WINDS BEGIN TO INCREASE ONCE AGAIN. .LONG TERM...WEDNESDAY THROUGH SATURDAY THE PARADE OF PACIFIC STORM SYSTEMS COMING OUT OF THE GULF OF ALASKA WILL CONTINUE THROUGH THE LONG TERM...AFFECTING THE FORECAST AREA ABOUT EVERY 24 TO 36 HOURS OR SO. THESE SYSTEMS...AND ASSOCIATED COLD FRONTS WILL KEEP TEMPERATURES BELOW AVERAGE FOR THE EXTENDED TIME FRAME. THE FIRST SYSTEM IN THE EXTENDED WILL AFFECT THE AREA WEDNESDAY THROUGH EARLY THURSDAY. ON WEDNESDAY...MOST OF THE SNOW WILL BE WEST OF THE DIVIDE...SPILLING EAST OF THE DIVIDE WEDNESDAY NIGHT...AS A COLD FRONT PUSHES SOUTH...EAST OF THE DIVIDE. THE PRECIPITATION WITH THIS SYSTEM SHOULD GRADUALLY EXIT THE AREA THURSDAY MORNING. CURRENTLY...IT APPEARS THIS SYSTEM WILL ONLY PRODUCE SOME LIGHT SNOW ACROSS THE AREA. THE NEXT SHORTWAVE TROUGH IS EXPECTED TO AFFECT THE AREA FRIDAY INTO EARLY SATURDAY. HOWEVER...THIS ONE APPEARS TO BE WEAK...WITH MAINLY ISENTROPIC UPGLIDE AFFECTING THE WESTERN WYOMING...AHEAD OF THE TROUGH...WITH LITTLE PRECIP EAST OF THE DIVIDE. BEYOND SATURDAY...MODELS DIVERGE CONSIDERABLE WITH THE NEXT SYSTEM...WITH THE OPERATIONAL GFS MUCH SLOWER THAN THE ECMWF WITH NEXT STORM SYSTEM. HAVE KEPT SOME SMALL POPS...ACROSS THE WEST FOR SUNDAY...FOR DECENT WESTERLY FLOW...AND/OR ISENTROPIC UPGLIDE ASSOCIATED AHEAD OF THE NEXT TROUGH. && .AVIATION... AN UPPER LEVEL DISTURBANCE WILL MOVE QUICKLY ACROSS THE REGION THROUGH THE MORNING. IT WILL PRIMARILY IMPACT WESTERN WYOMING...AND MVFR CIGS AND VSBYS ARE EXPECTED IN LIGHT SNOW AT KJAC THROUGH 18Z. OTHERWISE VFR CONDITIONS ARE EXPECTED ACROSS THE REST OF THE STATE WITH VICINITY SNOW SHOWERS IN THE FORECAST FOR THE REMAINING TAF SITES...MAINLY BETWEEN 12Z AND 18Z. STRONG SFC HIGH IN THE GREAT BASIN WILL REMAIN NEARLY STATIONARY THROUGH THE DAY...WHILE STRONG LOW PRESSURE WILL DEVELOP IN THE UPPER PLAINS STATES. THE PRESSURE GRADIENT BETWEEN THESE SYSTEMS WILL PRODUCE 15 TO 25 KT WINDS AT KCPR AND KRKS WITH GUSTS TO BETWEEN 30 AND 35 KT. KCOD WILL HAVE WEST WINDS AT 10 TO 15 KT WITH GUSTS TO AROUND 20 KT UNTIL AROUND 19Z DUE TO STRONG WEST WINDS ALOFT. WINDS AT THE REMAINING TAF SITES WILL GENERALLY BE BETWEEN 5 AND 10 KT. && .FIRE WEATHER... WIDESPREAD AND POSSIBLY SIGNIFICANT SNOWFALL IS EXPECTED ONCE AGAIN OVER WESTERN AND CENTRAL WYOMING LATE TONIGHT THROUGH MONDAY EVENING. STRONG WEST WINDS WILL ACCOMPANY THIS SYSTEM AS LOW PRESSURE DEVELOPS OVER EASTERN WYOMING MONDAY AFTERNOON. THE STRONG WINDS WILL CONTINUE MONDAY NIGHT INTO TUESDAY IN THE WIND CORRIDOR FROM THE RED DESERT TO CASPER. ANOTHER PACIFIC STORM IS EXPECTED ON WEDNESDAY. && .RIW WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM THIS EVENING THROUGH MONDAY EVENING FOR WYZ012-013-023-024. && SHORT TERM...CHURCH LONG TERM...WM AVIATION...C.BAKER FIRE WEATHER...CHURCH
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 313 PM MST SAT DEC 22 2007 WYZ001>020-022>030-231200- 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- 313 PM MST SAT DEC 22 2007 THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT A PACIFIC WEATHER SYSTEM WILL LIKELY DELIVER 1 TO 3 INCHES OF SNOWFALL TO THE WESTERN VALLEYS TONIGHT ALONG WITH 3 TO 5 INCHES OF SNOW TO THE WESTERN MOUNTAINS. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY A MAJOR WINTER STORM IS POSSIBLE FOR CHRISTMAS EVE IN WESTERN WYOMING WITH AT LEAST 3 TO 6 INCHES OF SNOW POSSIBLE IN THE WESTERN VALLEYS AND AS MUCH AS 6 TO 10 INCHES POSSIBLE IN THE WESTERN MOUNTAINS. ON CHRISTMAS EVE NIGHT AND INTO CHRISTMAS MORNING...SIGNIFICANT SNOWFALL WILL ALSO BE POSSIBLE EAST OF THE DIVIDE. ANOTHER POTENTIALLY STRONG STORM SYSTEM IS EXPECTED TO AFFECT THE COWBOY STATE WEDNESDAY AND THURSDAY. PLEASE STAY TUNED THIS HOLIDAY SEASON FOR THE LATEST FORECASTS AS A SERIES OF STORM SYSTEMS WILL CONTINUE TO IMPACT WESTERN AND CENTRAL WYOMING. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ENCOURAGED TO REPORT ANY SNOWFALL AMOUNTS TO THE NATIONAL WEATHER SERVICE THROUGH TONIGHT. THANK YOU. TEAM RIVERTON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE RIVERTON WY 323 AM MST SUN DEC 23 2007 WYZ012-013-023-024-027-231300- JACKSON HOLE-SALT RIVER AND WYOMING RANGES-SOUTH LINCOLN COUNTY- STAR VALLEY-TETON AND GROS VENTRE MOUNTAINS- 323 AM MST SUN DEC 23 2007 THROUGH DAYBREAK...LIGHT TO MODERATE SNOW WILL CONTINUE ACROSS FAR WESTERN WYOMING. TWO TO THREE INCHES OF SNOW COULD ACCUMULATE...WITH ISOLATED HIGHER AMOUNTS...ACROSS JACKSON HOLE AND STAR VALLEY. THE WESTERN MOUNTAINS COULD RECEIVE BETWEEN 3 AND 6 INCHES OF SNOW. HOLIDAY TRAVELLERS WILL EXPERIENCE SLICK AND SNOWPACKED ROADWAYS... INCLUDING TETON AND TOGWOTEE PASSES. IN ADDITION...VISIBILITY WILL BE REDUCED TO LESS THAN A MILE AT TIMES. MOST OF THE SNOW IS EXPECTED TO TAPER OFF BY MID MORNING. WYZ019-028>030-231300- EAST SWEETWATER COUNTY-FLAMING GORGE- GREEN MOUNTAINS AND RATTLESNAKE RANGE-ROCK SPRINGS AND GREEN RIVER- 323 AM MST SUN DEC 23 2007 ...VERY STRONG WEST WINDS ACROSS SWEETWATER COUNTY... VERY STRONG WEST WINDS ARE EXPECTED TO CONTINUE ACROSS SWEETWATER COUNTY THROUGH DAYBREAK. WEST WINDS SUSTAINED BETWEEN 30 AND 40 MPH...WITH GUSTS TO AROUND 55 MPH ARE EXPECTED TO CONTINUE FOR THE NEXT COUPLE OF HOURS. TRAVELLERS ON AREA ROADWAYS...ESPECIALLY ON NORTH TO SOUTH HIGHWAYS...WILL NEED TO BE READY FOR THESE STRONG CROSSWINDS. 21
The national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2007Every state in 2007This day in weather historyWarnings in Wyoming, December 2007
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: 65561.