Strong mountain top wind from the west-northwest produced sustained wind of 89 mph over Chief Joseph Pass along State Highway 296. The sustained speed over the pass was almost continuously above 60 mph for about seven hours.
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The episode as NWS RIW wrote it up.
Strong mountain top wind from the west-northwest produced sustained wind of 89 mph over Chief Joseph Pass along State Highway 296. The sustained speed over the pass was almost continuously above 60 mph for about seven hours. Southwest of Cody, a gust to 65 mph was measured about six miles up the valley of the South Fork of the Shoshone River.
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 Jan 12, 3:25 PM MST, 3 hours 15 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 325 PM MST MON JAN 12 2009 .SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT DRY NORTH-NORTHWEST FLOW ALOFT CURRENTLY OVER WESTERN AND CENTRAL WYOMING. CLEAR TO MOSTLY CLEAR SKY WILL ALLOW MOST VALLEY LOCATIONS TO COOL OFF EFFICIENTLY TONIGHT. FLOW BEGINS TO BACK TONIGHT AHEAD OF ANOTHER SHORT-WAVE TROUGH MOVING THROUGH NORTHERN ALBERTA. THIS FEATURE WILL INCREASE THE SURFACE PRESSURE GRADIENT OVER WYOMING TONIGHT. BREEZY CONDITIONS WILL KEEP THE TEMPERATURE IN THE MOUNTAINS AND BREEZY AREAS FROM FALLING MUCH. LOCAL 18Z WRF MODEL PROGGING CRITICAL LAYER ALONG WITH 70KT WIND SPEED JUST ABOVE THE NORTHERN ABSAROKA CREST LATE TONIGHT THROUGH TUESDAY. WRF MODEL OMEGA FIELD ALSO INDICATING A MOUNTAIN WAVE WILL SURFACE ALONG THE EASTERN SLOPES OF THE ABSAROKA IMPACTING TRAVEL ALONG THE CHIEF JOSEPH HIGHWAY WITH BLOWING SNOW AND POOR VISIBILITY. ISSUED HIGH WIND WATCH FOR WYZ002 AS A RESULT OF THE GOOD POTENTIAL FOR THE HIGH WIND TO SURFACE IN THE HIGHER TERRAIN. WINDY CONDITIONS ARE EXPECTED IN THE CODY FOOTHILLS BUT LATEST DATA SUGGESTING THE HIGH WIND VELOCITIES WILL REMAIN ABOVE THE BASIN FLOOR. STRONG SURFACE PRESSURE GRADIENT DEVELOPS OVER THE REGION TONIGHT AS A SURFACE LEE TROUGH DEVELOPS IN RESPONSE TO THE BACKING FLOW ALOFT. WINDY CONDITIONS EXPECTED TONIGHT AND TUESDAY IN THE USUAL PLACES...FROM JUST NORTHEAST OF ROCK SPRINGS TO CASPER. SEVERAL HOURS OF MARGINAL HIGH WIND POSSIBLE IN THE BEAVER RIM...GREEN MOUNTAINS AND RATTLESNAKE MOUNTAINS AREAS TUESDAY AFTERNOON BUT DECIDED TO FORGO HIGHLIGHTS BASES ON MARGINAL POTENTIAL AND A SOUTHWEST SFC PRESSURE GRADIENT WITH NORTHWEST WIND @ H7. ABOVE MENTIONED SHORT- WAVE TROUGH DIGGING SOUTHEASTWARD INTO THE NORTHERN PLAINS MOVES WELL NORTHEAST OF THE STATE BUT SENDS A CANADIAN COLD FRONT THROUGH JOHNSON NORTHEAST JOHNSON COUNTY EARLY WEDNESDAY MORNING. GOOD SURFACE CONVERGENCE ALONG WITH NORTHEAST UPSLOPE FLOW WILL PRODUCE WIDESPREAD LIGHT SNOW OVER THE BIGHORN MOUNTAINS AND ADJACENT JOHNSON COUNTY PLAINS BEGINNING EARLY WEDNESDAY MORNING. THE BOUNDARY SAGS SOUTHWARD INTO NATRONA COUNTY SOMETIME WEDNESDAY. GIVEN THE DEPTH AND STRENGTH OF MODIFIED ARCTIC AIRMASS CURRENTLY OVER THE NORTH- CENTRAL CANADA...EXPECTING THE COLD AIR TO PUSH SLIGHTLY FARTHER WEST THAN CURRENT MODEL SOLUTIONS WOULD INDICATE. TRENDED FORECAST TEMPERATURES IN THE CENTRAL BASINS SLIGHTLY DOWNWARD WEDNESDAY AND WEDNESDAY NIGHT WITH THE POTENTIAL FOR THE COLD AIR TO SLIDE SOUTHWARD THROUGH THE BIG HORN BASIN AND INTO THE WIND RIVER BASIN WEDNESDAY EVENING. NOT CONFIDENT INTRODUCING SLIGHT SNOW CHANCES JUST YET BUT EXPECTING AT LEAST A BRIEF SHOT FOR SOME SHALLOW MODIFIED ARCTIC AIR TO MAKE IT TO THE EASTERN SLOPES OF THE ABSAROKA...OWL CREEK AND WIND RIVER MOUNTAINS WEDNESDAY EVENING AND WEDNESDAY NIGHT. LONG TERM...THURSDAY THROUGH MONDAY EXTENDED FORECAST PRETTY QUIET AS WEST COAST RIDGE INCHES EAST...KICKING ANY RESIDUAL MOISTURE IN THE NORTHWEST FLOW OUT INTO THE PLAINS. NORTHWEST FLOW WILL BRING IN WARMER AIR FOR FRIDAY UNDER GOOD WARM AIR ADVECTION. MODELS BRINGING THROUGH A CLIPPER SHORTWAVE SATURDAY INTO SATURDAY NIGHT. THE MAIN IMPACT FROM THIS WILL BE SLIGHTLY COOLER TEMPERATURES AND SOME HIGH CLOUDS PASSING THROUGH. BY SUNDAY...THE DRY NORTHWEST FLOW RESUMES WITH MILD TEMPERATURES RETURNING. && .AVIATION... DRY NORTHWEST FLOW ALOFT WILL PRODUCE VFR CONDITIONS ACROSS WESTERN AND CENTRAL WYOMING TONIGHT. SURFACE LOW PRESSURE WILL DEVELOP ACROSS EASTERN WYOMING LATE TONIGHT AND DEEPEN IN THE NORTHERN PLAINS TUESDAY...WHILE STRONG SURFACE HIGH PRESSURE WILL MOVE EASTWARD INTO THE INTERIOR PACIFIC NORTHWEST AND THE NORTHERN GREAT BASIN. GUSTY WEST TO SOUTHWEST WINDS WILL DEVELOP ACROSS SWEETWATER COUNTY AND NATRONA COUNTY LATE TONIGHT AND TUESDAY BETWEEN LOW PRESSURE TO THE EAST AND HIGH PRESSURE TO THE WEST. KRKS AND KCPR CAN EXPECT SUSTAINED WINDS OF 20 TO 30 KT TUESDAY WITH GUSTS TO AROUND 40 KT. LIMITED MOISTURE IN NORTHWEST FLOW WILL PRODUCE SCATTERED MOUNTAIN OBSCURATIONS IN WESTERN WYOMING TUESDAY...BUT OTHERWISE SCATTERED MID TO HIGH LEVEL CLOUDS WILL MOVE ACROSS WYOMING WITH CONTINUED VFR CONDITIONS EXPECTED. && .FIRE WEATHER... STRONG WEST AND SOUTHWEST WIND WILL DEVELOP OVER PORTIONS OF CENTRAL WYOMING TONIGHT AND CONTINUE INTO TUESDAY. HIGH WIND IS POSSIBLE IN THE EASTERN ABSAROKA MOUNTAINS TONIGHT THROUGH TUESDAY. A BACKDOOR COLD FRONT WILL BRING COLDER TEMPERATURES AND SNOW TO THE BIGHORN MOUNTAINS AND JOHNSON COUNTY TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. AREAS OF LIGHT SNOW WILL CONTINUE OVER THE NORTHWEST MOUNTAINS TONIGHT THROUGH WEDNESDAY. && .RIW WATCHES/WARNINGS/ADVISORIES... HIGH WIND WATCH FROM 2 AM MST TUESDAY MORNING THROUGH TUESDAY AFTERNOON FOR WYZ002. && SHORT TERM...CHURCH LONG TERM...TWB AVIATION...SMITH FIRE WEATHER...CHURCH
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 428 AM MST MON JAN 12 2009 WYZ001>020-022>030-131300- 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- 428 AM MST MON JAN 12 2009 ...WINTER WEATHER ADVISORY THROUGH 11 AM FOR THE WESTERN BIGHORN MOUNTAINS... ...WINTER WEATHER ADVISORY UNTIL 9 AM MONDAY FOR NORTHERN JOHNSON COUNTY... ...WINTER WEATHER ADVISORY UNTIL 9 AM MONDAY FOR HOT SPRINGS COUNTY AND OWL CREEK/BRIDGER MOUNTAINS... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT ANOTHER STORM SYSTEM WILL BRING A QUICK ROUND OF SNOW TO NORTH-CENTRAL AND EAST-CENTRAL WYOMING THIS MORNING. THE HARDEST HIT AREAS WILL BE HOT SPRINGS COUNTY...NORTHERN JOHNSON COUNTY...THE OWL CREEK/BRIDGER MOUNTAINS AND THE WESTERN BIG HORN MOUNTAINS. WINTER WEATHER ADVISORIES ARE IN EFFECT FOR THESE AREAS THIS MORNING. SNOWFALL OF 6 TO 12 INCHES IN THE MOUNTAINS...WITH 3 TO 5 INCHES OVER LOWER ELEVATIONS CAN BE EXPECTED. TRAVEL WILL BECOME SNOWPACKED AND TREACHEROUS OVER THE PASSES TONIGHT IN THESE AREAS. AN INCH OR TWO CAN BE EXPECTED ELSEWHERE IN NORTH-CENTRAL AND EAST- CENTRAL WYOMING THIS MORNING. THE SNOW WILL WIND DOWN BY NOON... WITH SOME LINGERING LIGHT SNOW SHOWERS POSSIBLE. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SATURDAY THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT. 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 2009Every state in 2009This day in weather historyWarnings in Wyoming, January 2009
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: 142212, 142213.