A tight pressure gradient coupled with a favorable jet to produce high wind across the Green Mountains and Rattlesnake Hills and the Casper area. Gusts of 72 and 76 mph were recorded in the Rattlesnake Hills, while gusts in Casper topped 60 mph.
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The episode as NWS RIW wrote it up.
A tight pressure gradient coupled with a favorable jet to produce high wind across the Green Mountains and Rattlesnake Hills and the Casper area. Gusts of 72 and 76 mph were recorded in the Rattlesnake Hills, while gusts in Casper topped 60 mph. Mountain wave activity further enhanced the wind in and lee of the Absaroka Range in Northern Wyoming. A 122 mph gust was recorded in the Clark area and a gust of 94 mph was recorded along Chief Joseph Highway. The wind caused roof damage to a few buildings, blew part of a grain silo onto a highway, toppled power lines, and blew over several mailboxes around Clark and Cody.
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 Feb 11, 2:52 PM MST, 5 hours 48 minutes earlier.
AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE RIVERTON WY 252 PM MST FRI FEB 11 2011 UPDATED AVIATION DISCUSSION .SHORT TERM...TONIGHT THROUGH MONDAY VERY WINDY PATTERN SHAPING UP AS RIDGE OVER THE EASTERN PACIFIC SHIFTS INLAND...WITH A STRONG 150+KT JET MOVING INLAND ALONG THE SOUTHERN BC COAST. THE JET WILL CREST THE RIDGE NOSING INTO WYOMING OVERNIGHT INCREASING THE FLOW AND TIGHTENING THE GRADIENT AS IT DOES. SURFACE WIND SPEEDS INCREASE SIGNIFICANTLY TONIGHT IN THE USUAL PLACES...BUT ESPECIALLY OVER THE ABSAROKAS/CODY FOOTHILLS/GREEN MOUNTAINS/AND LOWER ELEVATIONS OF NATRONA COUNTY. WITH THE INITIAL NOSE OF THE JET COMING THROUGH...EXPECT HIGH WINDS IN THE ABSAROKAS AND CODY FOOTHILLS FROM JUST AFTER MIDNIGHT THROUGH MID/LATE MORNING. THERE IS ALSO POTENTIAL FOR THE GREEN MOUNTAINS AND NATRONA COUNTY AS WELL...THOUGH NOT UNTIL AROUND 6 AM AS THE JET NOSES DOWN THERE. ALSO...THE FLOW TAKES A LITTLE MORE TIME TO BACK THERE. WILL SEE A LULL IN BOTH AREAS LATE SATURDAY MORNING AND AFTERNOON AS THE INITIAL JET SHIFTS EAST. THE NEXT JET...MORE WEST TO EAST ORIENTED...MOVES INLAND SATURDAY AFTERNOON AND EVENING ACROSS THE US/CAN BORDER...REALLY TIGHTENING THE GRADIENT ACROSS WYOMING. H7 WINDS OF 40 TO 65 KTS...PER NAM12...WILL INCREASE THE WINDS AND KEEP THEM GOING SATURDAY NIGHT THROUGH MID DAY SUNDAY. THERE IS GOOD POTENTIAL FOR MOUNTAIN WAVE ACTIVITY SATURDAY NIGHT...PEAKING AROUND MIDNIGHT AS THE BEST MOUNTAIN TOP INVERSION AND ISENTROPIC FOLDING OCCURS THEN. SO THOSE FAVORED AREAS AROUND CLARK AS WELL AS THOSE ADJACENT TO CARTER AND CEDAR MOUNTAINS COULD SEE SOME WAVE BREAKING. THE JET SHIFTS EAST BY SUNDAY AFTERNOON WITH THE GRADIENT SLACKING QUICKLY BY EARLY EVENING. WILL GO AHEAD AND UPGRADE THE HIGH WIND WATCH TO A WARNING FOR THE ABSAROKAS AND CODY FOOTHILLS...WHICH STARTS AT MIDNIGHT TONIGHT AND CONTINUES THROUGH NOON SUNDAY. WILL MENTION THE LULL EXPECTED LATE SAT MORNING AND AFTERNOON. WILL LET THE WATCH RIDE FOR THE GREENS AND NATRONA COUNTY...WHICH IS IN EFFECT FROM 6 AM SATURDAY THROUGH NOON SUNDAY. THE REST OF THE AREA WILL BE QUITE WINDY AS WELL. EAST SLOPES OF THE BIGHORNS...WINDS AND THE UPPER WIND RIVER BASIN COULD COME CLOSE TO HIGH WIND...AND WILL NEED TO BE WATCHED. ISENTROPIC LIFT WILL BRING THE CHANCE OF LIGHT SNOW TO THE NORTHWEST MOUNTAINS TONIGHT AND AGAIN SATURDAY NIGHT. LIGHT SNOW IS POSSIBLE SUNDAY AS THE JET MOVES THROUGH SUNDAY. HOWEVER...IT IS QUITE DRY...SO DONT EXPECT MUCH ACCUMULATION. IT WILL BE MILD THE NEXT FEW DAYS WITH MOST AREAS IN THE 30S AND 40S...AND EVEN SOME LOWER 50S. RIDGE ACROSS THE ROCKIES MONDAY WITH WINDS INCREASING. THE MILD TEMPS CONTINUE. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY UNSEASONABLY MILD WEATHER TO PREVAIL OVER MUCH OF THE AREA THROUGH MID-WEEK WITH INCREASING CHANCES OF MOUNTAIN SNOW AND VALLEY RAIN/SNOW ACROSS THE WEST TUESDAY AND WEDNESDAY. SLOWER PROGRESSION OF COLD FRONT EXPECTED LATE IN THE WEEK WITH PACIFIC COLD FRONT NOW EXPECTED THROUGH AREA THURSDAY NIGHT...ALONG WITH CHANCES OF RAIN AND SNOW SHOWERS AND COOLER TEMPERATURES SPREADING EAST OF THE DIVIDE THURSDAY NIGHT AND FRIDAY. MEDIUM-RANGE GLOBAL MODELS SHOW INCREASING SPREAD THROUGH THIS PERIOD WITH GFS ON FAST END OF GUIDANCE WITH SHORTWAVES BREAKING DOWN UPPER RIDGE OVER ROCKIES ALONG WITH MAIN PACIFIC TROUGH GETTING KICKED INLAND ACROSS THE ROCKIES. ECMWF ON THE SLOW END OF GUIDANCE AND TRENDING SLOWER WITH ITS SOLUTION PREFERRED THROUGH THE PERIOD. LATEST ECMWF GUIDANCE IS 12-18 HOURS SLOWER THAN 24 HOURS AGO WITH PACIFIC FRONTAL PASSAGE TIMED FOR THURSDAY NIGHT. THUS...MAIN CHANGES TO FORECAST TONIGHT INVOLVE WARMING TEMPERATURES UP IN PREFRONTAL SW FLOW THURSDAY AND DELAYING COOL DOWN UNTIL FRIDAY. BEFOREHAND...UPPER TROUGH SHARPENS ACROSS EASTERN PACIFIC MONDAY AND BEGINS TO EJECT A SERIES OF SUCCESSIVELY STRONG SHORTWAVES UP BACKSIDE OF DOWNSTREAM RIDGE. FIRST SHORTWAVE WILL STAY WELL NORTH OF THE AREA MONDAY WITH A DRY WARM AIRMASS PREVAILING OVER THE AREA. SECOND SHORTWAVE WILL BRING SOME MOISTURE AND CHANCES OF PRECIPITATION INTO THE NORTHWEST TUESDAY AND BREEZY TO WINDY CONDITIONS EAST OF THE DIVIDE. UPPER RIDGE REBUILDS SOMEWHAT OVER AREA WEDNESDAY WITH UPPER TROUGH GETTING KICKED INLAND THURSDAY AND ACROSS ROCKIES THURSDAY NIGHT. && .AVIATION... VFR CONDITIONS WILL OCCUR TONIGHT OVER MOST OF THE REGION. WINDY CONDITIONS WILL CONTINUE AT KCOD...KCPR AND KRKS WITH POSSIBLE MOUNTAIN WAVE ACTION DEVELOPING ALONG THE ABSAROKAS OVERNIGHT. OTHERWISE VERY STRONG WINDS EXPECTED TO DEVELOP AT RIDGE TOP ALONG MOUNTAIN RANGES AND FROM THE KRKS TO KCPR CORRIDOR BEGINNING THIS EVENING AND PEAKING ON SATURDAY NIGHT INTO SUNDAY. LLWS COULD ALSO BE AN ISSUE IN MOST BASINS BEFORE INVERSIONS BREAK. WIND DIRECTIONS WILL BE DIFFICULT TO PIN DOWN IN THE WIND RIVER BASIN...STRONG NW WINDS WILL BLOW DOWN VALLEY THROUGH DUBOIS WHILE STRONG WESTERLIES WILL FLOW THROUGH THE WIND RIVER RANGE WHILE SW WINDS WILL BLOW ALONG THE RED DESERT...WHICH COULD WRAP AROUND THE WIND RIVER MTS AND FORCE SOUTHERLY WINDS OVER KRIW...WILL MOST CERTAINLY BE A TURBULENT DAY FOR AVIATION. && .FIRE WEATHER... IT WILL BE VERY WINDY ACROSS WESTERN AND CENTRAL WYOMING OVER THE WEEKEND. STRONG WINDS ARE EXPECTED IN THE ABSAROKAS AND CODY FOOTHILLS...WITH POTENTIAL IN THE GREENS AND RATTLESNAKES AS WELL AS THE LOWER ELEVATIONS OF NATRONA COUNTY. IT WILL BE MOSTLY DRY WITH ONLY A CHANCE OF LIGHT SNOW IN THE NORTHWEST TONIGHT...AND SATURDAY NIGHT AND SUNDAY. EXPECT THE WARMING TREND TO CONTINUE. && .RIW WATCHES/WARNINGS/ADVISORIES... HIGH WIND WARNING FROM MIDNIGHT TONIGHT THROUGH NOON MST SUNDAY WYZ002-003. HIGH WIND WATCH FROM SATURDAY MORNING THROUGH SUNDAY MORNING WYZ019-020. && SHORT TERM...TWB LONG TERM...AEM AVIATION...ALLEN FIRE WEATHER...TWB
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 309 PM MST FRI FEB 11 2011 WYZ001>020-022>030-121200- 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- 309 PM MST FRI FEB 11 2011 ...HIGH WIND WARNING FOR THE ABSAROKAS AND CODY FOOTHILLS AND FROM EARLY SATURDAY THROUGH MIDDAY SUNDAY... ...HIGH WIND WATCH FOR PARTS OF CENTRAL WYOMING FROM EARLY SATURDAY THROUGH MIDDAY SUNDAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TONIGHT STRONG WINDS ARE EXPECTED TO DEVELOP OVER THE ABSAROKA MOUNTAINS AND THE CODY FOOTHILLS AROUND MIDNIGHT. WEST WINDS OF 45 TO 55 MPH WITH GUSTS TO 80 MPH IN THE MOUNTAINS...WITH 35 TO 45 MPH WITH GUSTS TO 60 MPH ARE EXPECTED. PLEASE CHECK THE LATEST HIGH WIND WARNING FOR UPDATES...CYSNPWRIW. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY A BRIEF LULL IN THE WINDS ARE EXPECTED LATE SATURDAY MORNING AND AFTERNOON...BEFORE RESUMING SUNDAY NIGHT THROUGH MID DAY SUNDAY... POSSIBLY STRONGER. THOSE TRAVELING IN THESE AREAS WILL ENCOUNTER STRONG CROSS WINDS...ESPECIALLY ON 120 AND OVER CHIEF JOSEPH PASS. ALSO...HIGH WINDS MAY DEVELOP SATURDAY MORNING AND LAST THROUGH SUNDAY MORNING OVER SOUTHEAST FREMONT AND MUCH OF NATRONA COUNTY. SOUTHWEST WINDS OF 30 TO 40 MPH WITH GUSTS OVER 60 MPH ARE POSSIBLE. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE URGED TO REPORT WINDS GREATER THAN 40 MPH TONIGHT AS WELL AS ANY WIND DAMAGE. THANK YOU. TEAM RIVERTON
The national radar mosaic for the moment the first event began.
6 high wind. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2011Every state in 2011This day in weather historyWarnings in Wyoming, February 2011
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: 274826, 274831, 274829, 274832, 274827, 274830.