Strong northwest wind aloft coupled with a favorable atmosphere near mountaintop-level set the stage for another mountain wave near Clark. Very strong winds in excess of hurricane force blew in a narrow band near the foothills of the Absaroka Range during the early morning hours of Sunday, November 1.
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The episode as NWS RIW wrote it up.
Strong northwest wind aloft coupled with a favorable atmosphere near mountaintop-level set the stage for another mountain wave near Clark. Very strong winds in excess of hurricane force blew in a narrow band near the foothills of the Absaroka Range during the early morning hours of Sunday, November 1. The strongest gust was 88 mph at 0215MST, with multiple gusts exceeding 70 mph over about a 5-hour period. Other mesonet stations in Clark and along State Highway 120 south of Clark registered peak gusts around 60 mph between about 0400 and 0500MST.
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 Oct 31, 10:47 PM MST, 2 hours 43 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 1147 PM MDT SAT OCT 31 2015 .SHORT TERM...TONIGHT THROUGH SUNDAY (ISSUED AT 316 PM MDT) FIRST FOR THE ALL IMPORTANT HALLOWEEN NIGHT FORECAST. FOR THE KIDS TRICK OR TREATING...IT DOES LOOK DRY AND MILD. HOWEVER...IT WILL BE WINDY ACROSS THE USUAL AREAS LIKE ROCK SPRINGS TO CASPER AND IN THE LEE OF THE ABSAROKAS SO HOLD ON TO ANY HATS. FOR THE BIGGER KIDS GOING OUT LATER...IT LOOKS MAINLY DRY WITH COOLER TEMPERATURES. THE WIND SHOULD DECREASE A BIT WITH THE LOSS OF DAYTIME HEATING BUT IT WILL STILL BE BREEZY TO WINDY IN A LOT OF AREAS. A FAIRLY SIMILAR SITUATION TO YESTERDAY IN THAT THE MAJOR ISSUES THROUGH THE SHORT TERM ARE WIND EAST OF THE DIVIDE AND RAIN AND SNOW TO THE EAST. AS FOR WEST OF THE DIVIDE...RADAR CONTINUES TO SHOW SOME RAIN AND SNOW FALLING..ESPECIALLY ACROSS THE NORTHWEST. SNOW LEVELS HAVE RISEN FAIRLY HIGH HOWEVER...AROUND 7500 TO 8000 FEET AS OF AROUND NOON. WE EXPECT THE BEST SNOW TO BE THIS AFTERNOON BEFORE THE OFFENDING SHORTWAVE MOVES OUT AND THE SHOWERS TAPER OFF LATER THIS EVENING AND INTO TONIGHT. LIKE YESTERDAY...AMOUNTS SHOULD REMAIN BELOW ADVISORY CRITERIA. BY SUNDAY...ANOTHER WAVE WILL DROP IN COMBINED WITH SOME WARM ADVECTION TO PRODUCE ANOTHER SHOT OF RAIN AND SNOW SHOWERS ACROSS NORTHWESTERN WYOMING. AND...LIKE TODAY...THE AIRMASS SHOULD REMAIN FAIRLY WARM SO SNOW LEVELS SHOULD REMAIN RELATIVELY HIGH. THERE WILL ALSO BE GUSTY WINDS AROUND AS WELL WITH THE PRESSURE GRADIENT REMAINING TIGHT...ESPECIALLY ACROSS SOUTHERN AREAS. MEANWHILE...FURTHER EAST THE CONCERN CONTINUES TO BE THE WIND. SO FAR TODAY...THE WIND HAS BEHAVED FOR THE MOST PART WITH A SPECIAL WEATHER STATEMENT COVERING THINGS FAIRLY WELL. HOWEVER...THE USUAL PROBLEM CHILD...CLARK...HAS HAD SOME GUSTS OVER 50 MPH. GIVEN THE POTENTIAL FOR ANOTHER MOUNTAIN WAVE AND 700 MILLIBAR WINDS EXPECTED TO RISE ABOVE 60 KNOTS ONCE AGAIN...WE WILL HOIST ANOTHER HIGH WIND WARNING FOR THE CODY FOOTHILLS FOR LATER THIS AFTERNOON THROUGH TONIGHT. AS FOR DUBOIS...THE 700 MILLIBAR WINDS ARE NOT QUITE LINED UP CORRECTLY FOR THE STRONGEST WINDS. HOWEVER...FOR REASONS SO ELOQUENTLY WRITTEN BY COLLEAGUE KELLY ALLEN LAST NIGHT...WE WILL CONTINUE THE WARNING THIS AFTERNOON. ELSEWHERE...IT WILL BE WINDY BUT PROBABLY NOT HIGH WIND...ALTHOUGH AN ISOLATED GUST TO AROUND 58 MPH CAN NOT BE RULED OUT IN PLACES LIKE OUTER DRIVE IN CASPER. THE OTHER STORY WILL BE FOR ANOTHER DAY OF VERY WARM TEMPERATURES WITH HIGHS IN THE 60S FAIRLY WIDESPREAD ACROSS THE LOWER ELEVATIONS. .LONG TERM...SUNDAY NIGHT THROUGH SATURDAY PATTERN CHANGE IS STILL UNDERWAY AS WE TRANSITION FROM A LONGWAVE RIDGE OVER THE WEST TO LONGWAVE TROUGH THAT LOOKS TO PERSIST THROUGH THE UPCOMING WEEK IF NOT LONGER. APPROACHING TROUGH/LOW MOVING TOWARDS THE WRN B.C. COAST WILL START MOVING MORE SE AS THE UPSTREAM RIDGE BUILDS. THE LEADING EDGE OF THE BAROCLINIC BOUNDARY WITH POSSIBLE JET SUPPORT FROM EXITING JET AND NEW APPROACHING JET WILL PROBABLY ARRIVE LATE SUNDAY NIGHT OR TOWARDS SUNRISE MONDAY IN THE FAR SW/WCNTRL AREAS AND THEN INCREASE IN COVERAGE AND LIFT NWD DURING THE DAY. INTENSIFYING SURFACE LOW OVER NRN UT WILL MOVE INTO SWRN IF NOT THE FAR WESTERN PARTS OF CENTRAL WYO LATE MONDAY. WEAK PASSING WAVE TO THE NORTH COMBINED WITH THIS SURFACE LOW WILL DEVELOP A WEAK NLY FLOW WITH SOME UPSLOPE IN THE FAR NORTH. POSSIBLY STRONG ENOUGH WITH COLD AIR POOLING ALONG THE CODY FOOTHILLS TO WORRY ABOUT SNOW AS EARLY AS MONDAY MORNING. GUIDANCE TEMPS ARE KEEPING IT TOO WARM BUT IF THE PCPN HITS BY SUNRISE MONDAY...IT WILL DEFINITELY HAVE TO BE WATCHED. OUT WEST...SNOW WILL BE WIDESPREAD ON MONDAY IN THE FOOTHILLS AND MOUNTAINS WITH THE VALLEYS A TOUGH CALL. MODERATE TO HEAVY PCPN EARLY ENOUGH MONDAY COULD GET THE STAR AND JACKSON VALLEYS CHANGING OVER TO SNOW AND KEEPING THEM SNOW DURING THE DAY. ANY GAP IN PCPN OF DEPICTION LIKE THE NAM SHOWS WITH THE BAROCLINIC BOUNDARY LIFTING NWD DURING THE DAY SHUTTING DOWN PCPN WOULD NOT BE FAVORABLE. KEEPING PCPN GOING MONDAY WITH SNOW IN THE MORNING...CHANGING TO A MIXTURE IN THE VALLEYS IN THE AFTERNOON. TOUGH CALL. THIS INITIAL SHORTWAVE WEAKENS AS THE MORE DOMINANT SRN PART OF THE TROUGH COMES INTO PLAY MONDAY NIGHT AND TUESDAY. MODELS VARY SIGNIFICANTLY ON THE TRACK OF THIS MAIN UPPER LOW WITH MOST TAKING IT ACROSS NWRN WYOMING ON TUESDAY WHILE THE GFS AND 12Z NAM WHERE TRACKING IT A LITTLE FURTHER EAST AND MORE FAVORABLE FOR PARTS OF CENTRAL WYOMING FOR COLD PCPN TUESDAY INTO TUESDAY EVENING. 18Z NAM HAS TRENDED TOWARDS THE GEM AND ECMWF OVER WITH THE MID LEVEL CIRCULATION BEING OVER NWRN WYO TUESDAY AFTERNOON. THE NAM IS STILL KEEPING THE SURFACE LOW OVER SRN WYO ON TUESDAY. COLDER AIR USHERED IN WITH THIS TROUGH TUESDAY WITH SNOW TO THE VALLEY FLOOR OUT WEST AND LIKELY ABOVE 5K OR SO IN NCNTRL WYO. RAIN MAY ALSO CHANGE OVER TO SNOW IN PARTS OF CENTRAL WYOMING...ESPECIALLY AROUND THE LANDER FOOTHILLS TO DUBOIS TUESDAY AND POSSIBLY ACROSS THE BASIN FOR A LITTLE EITHER LATE IN THE AFTERNOON OR EARLY EVENING. A LOT WILL DEPEND ON THE CIRCULATION LOCATION. PCPN CONTINUES IN THE NORTH HALF TUESDAY NIGHT BEFORE DECREASING. COLD TROUGH SWINGS ACROSS WEDNESDAY NIGHT WITH A CHANCE OF LIGHT SNOW OR FLURRIES...MAINLY MTNS AND SOUTH. COLD NW FLOW THURSDAY AHEAD OF ANOTHER POTENTIAL SEWD MOVING SHORTWAVE FOR FRIDAY. GENERAL CONSENSUS WITH THE MODELS IS FOR THE BRUNT OF THE ENERGY TO MOVE JUST EAST OF US BUT STILL CLOSE ENOUGH TO PRODUCE AT LEAST MTN SNOW SHOWERS FRIDAY. WITH MEAN TROUGH STILL IN THE BIG PICTURE...WE'LL STILL HAVE TO WATCH THAT THIS WAVE DOESN'T END UP A LITTLE FURTHER WEST WITH TIME GIVING MORE OF THE AREA A CHANCE OF SNOW. OTHERWISE...THE MILD OCTOBER WEATHER GIVES WAY TO A MUCH COLDER AND UNSETTLED EARLY NOVEMBER. AN SPS IS BEING ISSUED TO PUT SOME PRELIMINARY SNOWFALL AMOUNTS IN FOR THE WEST OVER TO THE CODY FOOTHILLS MONDAY INTO TUESDAY. && .AVIATION.../06Z ISSUANCE EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST PERIOD. KCOD AND KCPR ARE TO HAVE THE GUSTY WIND THROUGH SUNDAY. A GUSTY WIND AT KRIW AND KLND SUNDAY AFTERNOON. THE WIND WILL DECREASE AFTER 01Z MONDAY. THE STRONG WIND ALOFT OVER WY WILL CONTINUE THROUGH SUNDAY NIGHT. SOME MOUNTAIN WAVE ACTIVITY WILL RESULT AND AREAS OF MOUNTAIN TURBULENCE AND SOME LLWS ON THE LEE SIDE OF MOUNTAIN RANGES CAN BE EXPECTED. PLEASE SEE THE AVIATION WEATHER CENTER FOR THE LATEST TURBULENCE FORECAST. WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES MVFR CONDITIONS WILL OCCUR OVER NW WY WITH SOME IFR CONDITIONS THROUGH SUNDAY NIGHT. THIS WILL INCLUDE THE KJAC TERMINAL SITE. RAIN AND MOUNTAIN SNOW WILL DEVELOP BY 12Z IN NW WY AND CONTINUE INTO SUNDAY NIGHT. IN SOUTHWEST WY...VFR CONDITIONS WILL OCCUR THROUGH 15Z. THEN VFR TO MVFR CONDITIONS WILL OCCUR AFTER 15Z THROUGH 06Z MONDAY. SCATTERED RAIN SHOWERS WILL DEVELOP AFTER 18Z SUNDAY IN SW WY WITH SNOW IN THE HIGHER MOUNTAINS. A GUSTY WIND WILL OCCUR MAINLY AFTER 17Z SUNDAY UNTIL 01Z MONDAY AT THE THREE TERMINAL SITES IN SW WY. EXPECT MOUNTAIN TURBULENCE DUE TO THE STRONG WIND ALOFT. PLEASE SEE THE AVIATION WEATHER CENTER FOR THE LATEST ICING AND TURBULENCE FORECAST FOR WESTERN WY. && .FIRE WEATHER... A SERIES OF UPPER LEVEL DISTURBANCES WILL BRING A CONTINUED CHANCE OF SHOWERS TO AREAS WEST OF THE DIVIDE...ESPECIALLY ACROSS NORTHWESTERN WYOMING THROUGH MONDAY. DRY AND WINDY WEATHER WITH ABOVE NORMAL TEMPERATURES WILL CONTINUE EAST OF THE DIVIDE THROUGH THE WEEKEND. HOWEVER...RELATIVE HUMIDITY IS EXPECTED TO REMAIN ABOVE CRITICAL LEVELS. THE CHANCE FOR A WETTING RAIN AND SNOW BECOMES MORE LIKELY WEST OF THE DIVIDE FOR MONDAY AND FOR MOST AREAS ON TUESDAY. && .RIW WATCHES/WARNINGS/ADVISORIES... HIGH WIND WARNING UNTIL 5 AM MST SUNDAY FOR WYZ003. HIGH WIND WARNING UNTIL 5 AM MST SUNDAY FOR WYZ016. && SHORT TERM...HATTINGS LONG TERM...SKRBAC AVIATION...AR FIRE WEATHER...HATTINGS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 259 PM MDT SAT OCT 31 2015 WYZ001>020-022>030-012100- 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- 259 PM MDT SAT OCT 31 2015 ...HIGH WIND WARNING FOR THE CODY FOOTHILLS AND UPPER WIND RIVER BASIN THROUGH 5AM SUNDAY MORNING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TONIGHT STRONG WINDS WITH WIND GUSTS OVER 60 MPH ARE LIKELY ALONG THE CODY FOOTHILLS AND UPPER WIND RIVER BASIN THROUGH TONIGHT. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY SUNDAY...GUSTY WEST WINDS CONTINUE ACROSS MUCH OF THE AREA WITH STRONGEST WINDS IN THE MOUNTAINS. MORE SNOW POSSIBLE ACROSS THE NORTHWEST WITH ACCUMULATION POSSIBLE ABOVE 8000 FEET. SUNDAY NIGHT AND MONDAY... A COLD FRONT WILL BRING INCREASING RAIN AND SNOW ACROSS THE WEST SUNDAY NIGHT WITH SNOW LEVELS LOWERING TO VALLEY FLOORS BY SUNDAY EVENING.. TUESDAY AND WEDNESDAY...A CANADIAN COLD FRONT WILL SPREAD AREAS OF SNOW AND COLDER TEMPERATURES SOUTH ACROSS CENTRAL WYOMING TUESDAY MORNING. AREAS OF SNOW WILL CONTINUE INTO WEDNESDAY WITH THE HEAVIEST SNOW POSSIBLE TUESDAY AND TUESDAY NIGHT...ESPECIALLY IN UPSLOPE FAVORED AREAS OR ALONG NORTH AND EAST FACING SLOPES. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ENCOURAGED TO REPORT SNOW AMOUNTS AND WIND GUSTS OVER 55 MPH AS WELL AS ANY WIND DAMAGE. THANK YOU.
The national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
The wind prone areas near Clark had several wind gusts past 58 mph. The maximum wind gust was 88 mph to the west of Clark at 0215MST.
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, November 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: 603516.