An upper-level disturbance and associated strong mid and upper-level winds moved across Wyoming and produced high winds in northwest and central portions of the state. The highest winds were in the Absaroka Range where winds were sustained as high as 73 mph.
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The episode as NWS RIW wrote it up.
An upper-level disturbance and associated strong mid and upper-level winds moved across Wyoming and produced high winds in northwest and central portions of the state. The highest winds were in the Absaroka Range where winds were sustained as high as 73 mph. Gusts on Chief Joseph Pass roared past hurricane force with a maximum of 96 mph. In addition, mountain wave activity produced high winds near Clark and Lander, where maximum gusts of 86 mph and 59 mph were recorded, respectively. Across central Wyoming, a tight pressure gradient produced high winds in Natrona County. A peak gust of 70 mph was registered along Outer Drive on the south side of Casper.
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 6, 5:57 PM MST, 44 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 557 PM MST SUN DEC 6 2015 .UPDATE... UPGRADED HIGH WIND WATCH TO A WARNING FOR THE CODY FOOTHILLS...AND CANCELLED THE OTHER HIGH WIND WATCHES FOR THE EAST SLOPES OF THE DIVIDE. ALSO ADJUSTED TIMES FOR HIGH WIND WATCH FOR NATRONA AND SOUTHERN FREMONT COUNTY THAT WILL LIKELY SEE STRONGEST WINDS FROM LATE MONDAY MORNING THROUGH MONDAY EVENING. && .PREV DISCUSSION... /ISSUED 152 PM MST SUN DEC 6 2015/ SHORT TERM...TONIGHT THROUGH MONDAY HIGH WIND THREAT WITH POTENTIAL MO0UNTAIN WAVES FORMING THIS EVENING ALONG AND NEAR THE EAST SLOPES OF THE ABSAROKA AND WIND RIVER MOUNTAINS WITH HIGH WINDS POTENTIALLY PROPAGATING EAST ACROSS SOUTHERN FREMONT AND NATRONA COUNTIES. LARGE AREA OF DRYING ON WATER VAPOR OVER OREGON AND NORTHERN NEVADA MOVING INTO WESTERN IDAHO INDICATING SIGNIFICANT DOWNWARD MOTION IN THE RIGHT FRONT REGION OF THE JET. THIS EXTRAPOLATES TO THE CONTINENTAL DIVIDE AROUND 06Z. WINDS HAVE BEEN ELEVATED IN SOUTHERN NATRONA COUNTY AT OUTER DRIVE SOUTH SIDE OF CASPER AND NOT A BIG JUMP TO REACH THE WARNING THRESHOLD. WILL KEEP HIGH WIND WATCH FOR NOW AND LET EVENING SHIFT DETERMINE IF UPGRADING IS NEEDED. WEST OF THE CONTINENTAL DIVIDE PACIFIC MOISTURE AND STRONG ZONAL FLOW WILL PRODUCE SNOWFALL THIS EVENING THROUGH MONDAY WITH 4 TO 6 INCHES IN THE MOUNTAINS AND 2 TO 3 INCHES IN THE VALLEYS EXPECTED AT THIS TIME. THERE SHOULD BE A BREAK MONDAY AFTERNOON BEFORE MORE SNOW MOVES IN THROUGH THE EVENING. WIND... CLOUDS AND PRECIPITATION WILL HELP MODERATE TEMPERATURES. MAY SEE SOME RAIN MIXED WITH SNOW IN STAR VALLEY AND JACKSON HOLE IN THE AFTERNOON HOURS. LONG TERM...MONDAY NIGHT THROUGH SUNDAY BUSY PATTERN IN THE LONG TERM WITH SEVERAL WAVES OF SNOW ACROSS THE WEST...POSSIBLY MIXED WITH RAIN IN THE LOW ELEVATIONS AT TIMES... WITH PLENTY OF WINDY DAYS AHEAD ACROSS THE AREA. TIMING THESE SYSTEMS AND PINNING DOWN WHEN THE PATTERN AMPLIFIES A BIT NEXT WEEK WILL BE THE MAIN FORECAST CHALLENGES. THE FIRST PUSH OF MOISTURE DURING THE LONG TERM PERIOD WILL MOVE OVER THE NORTHWEST MONDAY EVENING CONTINUING THROUGH TUESDAY. THERE COULD BE SOME SIGNIFICANT ACCUMULATIONS IN THE TETONS AND SOUTHERN YELLOWSTONE NATIONAL PARK...AT LEAST OVER 10 INCHES...WITH 4 INCHES POSSIBLE IN THE VALLEYS. A MILD AIRMASS WILL MOVE IN FOR TUESDAY...POSSIBLY CHANGING SNOW TO RAIN DURING THE DAY ON TUESDAY...REFREEZING OVERNIGHT DURING A LULL IN THE ACTION. THIS COULD CAUSE SOME ICY AREAS AND DIFFICULT DRIVING CONDITIONS. IT WILL CONTINUE TO BE VERY WINDY EAST OF THE DIVIDE WITH SOME 50KT NORTHWEST WIND BARBS SHOWING UP EARLY ON TUESDAY. SURFACE FLOW WILL BE MORE WEST TO SOUTHWESTERLY BUT A FEW OF THOSE GUSTS COULD MIX DOWN INTO THE FOOTHILLS AND WILL BE COMMON AGAIN IN THE MOUNTAINS. THERE WILL BE A BIT OF A LULL ON WEDNESDAY AHEAD OF THE NEXT SYSTEM. ANOTHER WAVE ARRIVES LATE WEDNESDAY NIGHT AS ANOTHER SHORT WAVE ZIPS BY...SPREADING SNOW AND RAIN A LITTLE FURTHER SOUTH WHILE IT REMAINS VERY WINDY EAST OF THE DIVIDE...50KT WIND BARBS COMMON AT H7 WEDNESDAY NIGHT WITH SOME 70-80KT BARBS ALONG THE BIGHORNS AND I25 CORRIDOR WITH A VERY TIGHT GRADIENT REMAINING AT THE SURFACE. THE PATTERN BEGINS TO AMPLIFY AS A TROUGH DIGS ACROSS THE WEST ON THURSDAY...LIKELY BRINGING SOME MORE WIDESPREAD PRECIPITATION INTO THE REGION ON THURSDAY NIGHT OR FRIDAY. THIS SYSTEM IS SPLITTING LIKE MOST SYSTEMS THIS TIME OF YEAR...SO THE ULTIMATE IMPACT OF THE SYSTEM WILL DEPEND ON HOW FAR IT TAKES THE DYNAMIC ENERGY AWAY FROM OUR AREA. AS IT APPEARS NOW...THERE COULD BE SOME SIGNIFICANT SNOW IN THE WESTERN MOUNTAINS WITH A CHANCE FOR SOME SNOW AND RAIN MOVING ACROSS THE SOUTH AND EAST OF THE DIVIDE ON FRIDAY. COLD NORTHERLY FLOW COULD FOLLOW FOR SATURDAY WITH LITTLE PRECIPITATION TO SPEAK OF. FLOW BECOMES MORE NORTHWESTERLY AGAIN ON SUNDAY WITH ANOTHER STORM ON THE WAY FOR EARLY NEXT WEEK...WITH MORE SNOW POSSIBLE ON BOTH SIDES OF THE DIVIDE. THIS LAST SYSTEM WILL BE COLDER SO IT WILL LIKELY BE ALL SNOW. AVIATION.../00Z ISSUANCE/ WEST OF THE CONTINENTAL DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES WEST TO SOUTHWEST FLOW ALOFT WITH INCREASING PACIFIC MOISTURE WILL BRING INCREASED MID AND HIGH CLOUDS TO WESTERN WYOMING. CEILINGS WILL BEGIN TO LOWER AROUND 00Z WITH AREAS OF IFR TO MVFR CEILINGS AND VISIBILITY REDUCED IN SNOW INCREASING THROUGH THE NIGHT AND IMPACTING KJAC AND KAFO BY 05Z. MOUNTAINS WILL BECOME OBSCURED. SNOW SHOWERS EXPECTED VICINITY KPNA 09Z AND KBPI 13Z. AREAS OF LOW LEVEL WIND SHEAR WILL BECOME WIDESPREAD OVER AND NEAR THE MOUNTAINS. EAST OF THE CONTINENTAL DIVIDE...KCPR/KCOD/KLND/KRIW/KRIW ROUTES WEST TO SOUTHWEST FLOW ALOFT WITH INCREASING PACIFIC MOISTURE WILL BRING INCREASED MID AND HIGH CLOUDS TO WESTERN WYOMING. VFR CONDITIONS ARE EXPECTED AT THE AIRPORTS...ACROSS ALL OF THE LOWER ELEVATIONS. OVER THE MOUNTAINS ALONG AND NEAR THE CONTINENTAL DIVIDE MVFR/IFR CEILINGS WILL INCREASE 00Z TO 06Z WITH VISIBILITY REDUCED IN SNOW OBSCURING MOUNTAINS. ALONG AND NEAR THE MOUNTAINS STRONG WINDS WILL CAUSE LOW LEVEL WIND SHEAR. FIRE WEATHER... HIGH WIND THREAT WITH POTENTIAL MO0UNTAIN WAVES FORMING THIS EVENING ALONG AND NEAR THE EAST SLOPES OF THE ABSAROKA AND WIND RIVER MOUNTAINS WITH HIGH WINDS POTENTIALLY PROPAGATING EAST ACROSS SOUTHERN FREMONT AND NATRONA COUNTIES. LARGE AREA OF DRYING ON WATER VAPOR OVER OREGON AND NORTHERN NEVADA MOVING INTO WESTERN IDAHO INDICATING SIGNIFICANT DOWNWARD MOTION IN THE RIGHT FRONT REGION OF THE JET. THIS EXTRAPOLATES TO THE CONTINENTAL DIVIDE AROUND 06Z. WINDS HAVE BEEN ELEVATED IN SOUTHERN NATRONA COUNTY AT OUTER DRIVE SOUTH SIDE OF CASPER AND NOT A BIG JUMP TO REACH THE WARNING THRESHOLD. WILL KEEP HIGH WIND WATCH FOR NOW AND LET EVENING SHIFT DETERMINE IF UPGRADING IS NEEDED. WEST OF THE CONTINENTAL DIVIDE PACIFIC MOISTURE AND STRONG ZONAL FLOW WILL PRODUCE SNOWFALL THIS EVENING THROUGH MONDAY WITH 4 TO 6 INCHES IN THE MOUNTAINS AND 2 TO 3 INCHES IN THE VALLEYS EXPECTED AT THIS TIME. THERE SHOULD BE A BREAK MONDAY AFTERNOON BEFORE MORE SNOW MOVES IN THROUGH THE EVENING. WIND... CLOUDS AND PRECIPITATION WILL HELP MODERATE TEMPERATURES. MAY SEE SOME RAIN MIXED WITH SNOW IN STAR VALLEY AND JACKSON HOLE IN THE AFTERNOON HOURS. WHILE MIXING HEIGHTS WILL BE RELATIVELY LOW...STRONG TRANSPORT WINDS SHOULD BUMP SMOKE DISPERSAL INTO LOW END GOOD THRESHOLD...EXPECT WHERE SNOWFALL IS OCCURRING AND THERE SMOKE DISPERSAL WILL REMAIN POOR. && .RIW WATCHES/WARNINGS/ADVISORIES... HIGH WIND WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING FOR WYZ019-020. HIGH WIND WARNING UNTIL NOON MST MONDAY FOR WYZ003. UPDATE...AEM SHORT TERM...C.BAKER LONG TERM...ALLEN AVIATION...C.BAKER FIRE WEATHER...C.BAKER
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 550 PM MST SUN DEC 6 2015 WYZ001>020-022>030-071200- YELLOWSTONE NATIONAL PARK-ABSAROKA MOUNTAINS-CODY FOOTHILLS- NORTH BIG HORN BASIN-SOUTHWEST BIG HORN BASIN- SOUTHEAST BIG HORN BASIN-OWL CREEK AND BRIDGER MOUNTAINS- BIGHORN MOUNTAINS WEST-BIGHORN MOUNTAINS SOUTHEAST- NORTHEAST JOHNSON COUNTY-SOUTHEAST JOHNSON COUNTY- TETON AND GROS VENTRE MOUNTAINS-JACKSON HOLE- WIND RIVER MOUNTAINS WEST-WIND RIVER MOUNTAINS EAST- UPPER WIND RIVER BASIN-WIND RIVER BASIN-LANDER FOOTHILLS- GREEN MOUNTAINS AND RATTLESNAKE RANGE- NATRONA COUNTY LOWER ELEVATIONS-CASPER MOUNTAIN-STAR VALLEY- SALT RIVER AND WYOMING RANGES-UPPER GREEN RIVER BASIN FOOTHILLS- UPPER GREEN RIVER BASIN-SOUTH LINCOLN COUNTY- ROCK SPRINGS AND GREEN RIVER-FLAMING GORGE-EAST SWEETWATER COUNTY- 550 PM MST SUN DEC 6 2015 ...HIGH WIND WARNING FOR THE CODY FOOTHILLS UNTIL NOON MST MONDAY... ...HIGH WIND WATCH FOR MOST OF NATRONA COUNTY AND PORTIONS OF SOUTHERN FREMONT COUNTY LATE MONDAY MORNING THROUGH MONDAY EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WEST AND CENTRAL WYOMING. .DAY ONE...TONIGHT STRONG WIND GUSTS OF 60 TO 75 MPH ALONG THE CODY FOOTHILLS TONIGHT THROUGH MONDAY MORNING. SEE HIGH WIND WARNING FOR MORE INFORMATION. SNOWFALL OF 2 TO 4 INCHES OVER THE NORTHWEST MOUNTAINS INCLUDING TOGWOTEE AND TETON PASSES TONIGHT WITH MOST OF THE SNOW EXPECTED DURING THE EVENING. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY MONDAY...STRONG WIND GUSTS OF 60 TO 75 MPH IN THE CODY FOOTHILLS IN THE MORNING. HIGH WINDS DEVELOPING ACROSS SOUTHERN FREMONT AND MOST OF NATRONA COUNTY LATE MONDAY MORNING AND CONTINUING THROUGH MONDAY EVENING. PLEASE SEE HIGH WIND WATCHES AND WARNINGS FOR THE LATEST INFORMATION. MONDAY NIGHT AND TUESDAY...SNOW INCREASING ACROSS THE WESTERN MOUNTAINS AND FAR WEST VALLEYS MONDAY NIGHT AND CONTINUING THROUGH TUESDAY. AREAS OF BLOWING SNOW OVER OPEN AREAS. VERY WINDY CONDITIONS CONTINUE ALONG THE CODY FOOTHILLS AND FROM THE RED DESERT TO THE CASPER AREA. WEDNESDAY THROUGH THURSDAY NIGHT...A COUPLE OF QUICK MOVING SYSTEMS COULD BRING SIGNIFICANT SNOW AND...OR BLOWING SNOW OVER THE FAR WEST. EAST OF THE DIVIDE...STRONG TO POSSIBLY HIGH WIND COULD OCCUR AT TIMES IN THE CODY FOOTHILLS...AND THE WIND CORRIDOR FROM JEFFREY CITY TO CASPER. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ALSO ASKED TO REPORT ANY WIND GUSTS GREATER THAN 50 MPH. THANK YOU.
The national radar mosaic for the moment the first event began.
6 high wind. Local standard time, as filed.
The wind sensor 5 miles west-northwest of Clark recorded wind gusts of 81 and 76 mph.
Strong winds occurred along the Chief Joseph highway. Winds were sustained as high as 73 mph. Many gusts over hurricane force were recorded, including a maximum of 96 mph.
Several wind gusts over 58 mph were recorded on Outer Drive north of Casper, including a maximum gust of 70 mph.
The RAWS site at Fales Rock recorded several wind gusts over 58 mph including a maximum of 68 mph.
The wind sensor 5 miles west-northwest of Clark recorded several wind gusts in excess of hurricane force with a peak of 86 mph.
The wind sensor along the North Fork of the Popo Agie river recorded wind gusts of 58 and 59 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2015Every state in 2015This day in weather historyWarnings in Wyoming, December 2015
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: 607079, 607086, 607084, 607082, 612579, 607085.