A favorable combination of strengthening winds aloft and a tightening pressure gradient produced high wind in central Wyoming. Wind gusts of 58 to 69 mph were recorded for six consecutive hours.
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The episode as NWS RIW wrote it up.
A favorable combination of strengthening winds aloft and a tightening pressure gradient produced high wind in central Wyoming. Wind gusts of 58 to 69 mph were recorded for six consecutive hours.
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 1, 2:31 PM MST, 10 hours 39 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 231 PM MST WED DEC 1 2010 SHORT TERM...TONIGHT THROUGH SATURDAY FIRST PERIOD OF ISENTROPIC UPGLIDE AND PERHAPS EVEN A LITTLE JET SUPPORT BROUGHT 3 TO 5 INCHES TO THE TETONS WITH 1 TO 3 INCHES ACROSS THE LOWER ELEVATIONS. A LITTLE MORE MAY HAVE FALLEN AROUND ALPINE WHERE MODERATE SNOW PERSISTED FOR A LARGE PORTION OF THE DAY. LIGHT SNOW WILL PERSIST ACROSS THE WEST TONIGHT BUT AMOUNTS LOOK TO BE A LITTLE LIGHTER. OUR NEXT SYSTEM IS STILL POISED TO MOVE INTO THE FAR WEST AFTER 18Z THURSDAY AND CONTINUE INTO FRIDAY MORNING. ISENTROPIC UPGLIDE INCREASING AS DOES PW. 110KT JET WILL ALSO SAG SWD OVER THE AREA WHICH MAY PROVIDE BETWEEN 6 AND 12 HOURS OF UPPER DIVERGENCE. COMBINATION OF UPGLIDE...JET SUPPORT...OROGRAPHICS AND HIGHER THAN AVERAGE PW'S UP TO .40 SHOULD PROVIDE FOR THE POTENTIAL FOR HEAVY SNOW CENTERED ON TETON COUNTY. THE HEAVIER SNOW COULD EXTEND INTO YNP AND AS FAR SOUTH AS THE STAR VALLEY...ESPECIALLY THE NORTH HALF. HAVE DECIDED TO ISSUE A WINTER STORM WATCH FOR ZONES 12 AND 13. THE NEXT SHIFT CAN LOOK FURTHER AT THE POTENTIAL IN YNP AND THE STAR VALLEY. I THINK ALPINE WILL SEE POTENTIAL WARNING AMOUNTS BUT NOT CONFIDENT ENOUGH FOR THE SRN PORTION YET TO ISSUE ANY WATCHES. YNP LOOKS GOOD FOR THE NORMALLY SNOWY SOUTH BUT NOT SURE THE 12 INCH AMOUNTS WILL BE WIDESPREAD ENOUGH. WE CAN ALWAYS ADD THEM IN YET OR JUST GO WITH AN ADVISORY DOWN THE ROAD WITH 12 INCH PLUS AMOUNTS INDICATED IN THE NORMALLY SNOWY SRN AREAS. WINDS WILL ALSO BE A PROBLEM WITH THIS STORM AS MTN TOP FLOW INCREASES TO 40KTS PLUS AND APPROACHING FRONT SHOULD ALLOW EVEN THE VALLEYS TO PICK UP THURSDAY NIGHT. SNOW SHOULD TAPER OFF LATE FRIDAY MORNING WITH ANOTHER ROUND OF LIGHT ISENTROPIC UPGLIDE PCPN QUICKLY REDEVELOPING ON SATURDAY IN THE FAR WEST. EAST OF THE DIVIDE...THE MAIN CONCERN WILL BE THE WIND POTENTIAL THURSDAY NIGHT INTO FRIDAY MORNING. GOOD GAP FLOW EVENT DEVELOPING AGAIN FOR THE CODY FOOTHILLS THURSDAY NIGHT WITH THE POTENTIAL FOR MTN WAVE ACTIVITY WITH STABLE MTN TOP LAYER...SUFFICIENT FLOW INTO THE BARRIER AND A FROUDE NUMBER CALCULATED TO BE NEAR 1. LCL WRF IS NOT SHOWING ANY WAVE BREAKING IN ITS RUN BUT IT DOES SHOW 40 TO 50 KT AT THE BOUNDARY LAYER PUSHING INTO CODY AND SOUTH OF CLARK ON THE 06Z RUN. THE 18Z IS CONFINED MORE TO CODY. ENOUGH CONFIDENCE IN AT LEAST A GAP FLOW EVENT TO ISSUE A HIGH WIND WATCH FOR THIS TIME PERIOD. RIGHT FRONT QUAD OF APPROACHING JET MAY ALSO PROVIDE SOME DOWNWARD FORCING THURSDAY NIGHT. WE ALSO ARE SEEING SOME MTN WAVE POTENTIAL ALONG THE EAST SLOPE OF THE WIND RIVER MTNS THURSDAY NIGHT AS 30KT INBOUND FLOW BECOMES 70KTS ON THE LCL WRF IN THE HIGHER FOOTHILLS AND JUST DOWNWIND OF THE CREST. IT DOES NOT SHOW IT MOVING INTO LANDER OR FT. WASHAKIE BUT IT COULD BE VERY WINDY OVER SOUTH PASS AND OVER THE EAST SLOPE OF THE WINDS THURSDAY NIGHT INTO SUNRISE FRIDAY. OUR WIND CORRIDOR SHOULD ALSO SEE A DRAMATIC INCREASE THURSDAY EVENING AS INCREASING WSW H7 FLOW AND FALLING PRESSURE CREATE ENOUGH POTENTIAL FOR HIGH WINDS IN AT LEAST THE GREENS AND RATTLESNAKES. THE NEXT SHIFT CAN ALSO LOOK AT THE LOWER ELEVATIONS OF NATRONA COUNTY. NOT SURE IF THE SURFACE PRESSURE GRADIENT WILL BE ENOUGH TO PUSH IT INTO HIGH WINDS OR JUST VERY WINDY. COLD FRONT THEN MOVES DOWN EAST OF THE DIVIDE FRIDAY MORNING IN THE FAR NORTH AND IN THE SOUTH BY AFTERNOON OR EARLY EVENING. A CHANCE OF SNOW LOOKS GOOD IN THE NRN ZONES FRIDAY AFTERNOON BUT NOT IN OUR CENTRAL ZONES AS OF NOW. BRIEF SHORTWAVE RIDGING FRIDAY NIGHT WITH ANOTHER ROUND OF ISENTROPIC UPGLIDE POSSIBLY MOVING BACK INTO THE WEST SATURDAY ALREADY FOR MORE LIGHT SNOW. LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY MOSTLY DRY CONDITIONS WITH NEAR OR SLIGHTLY BELOW NORMAL TEMPERATURES ARE EXPECTED ACROSS THE NORTH CENTRAL THROUGH THIS PERIOD. CHANCES OF LIGHT SNOW ACROSS THE WEST AND SOUTH ARE FORECAST SATURDAY THROUGH MONDAY WITH MORE SIGNIFICANT SNOWFALL POSSIBLE ACROSS THE WEST TUESDAY AND WEDNESDAY. MEDIUM-RANGE GLOBAL MODELS SHOW QUITE A BIT OF SPREAD FROM THE OUTSET THIS MORNING. THE OVERALL PATTERN WILL INITIALLY CONSIST OF A BUILDING RIDGE OVER WEST CENTRAL CANADA OVER THE WEEKEND FLANKED BY UPPER LOWS OVER THE GULF OF ALASKA AND THE NE COAST. ECMWF SHOWS STRONGER CLIPPER SYSTEM DIVING INTO NORTHERN PLAINS EARLY SUNDAY THAT WOULD PUSH A BACKDOOR COLD FRONT ACROSS THE NE HALF OF THE CWA. GFS TRAPS THIS ENERGY UNDER A MORE CLOSED UPPER HIGH OVER THE NORTHERN ROCKIES. THE NEXT BIG DIFFERENCES ARISE WITH PROGRESSION OF SW LOW. ECMWF/GEM/GFS ALL HAVE THIS SYSTEM NEAR 32N/130W 12Z SUNDAY WITH GFS KICKING OPEN WAVE ACROSS FOUR CORNERS AREA BY 12Z MONDAY WHILE ECMWF AND GEM KEEP THIS ENERGY OFFSHORE THROUGH 12Z MONDAY. KICKER CROSSING 140W WOULD TEND TO FAVOR GFS THOUGH CONFIDENCE REMAINS LOW WITH DETAILS OF TIMING. GFS LIKELY TO WET ACROSS MOST OF WYOMING IN THIS SPLIT FLOW REGIME AND FORECAST KEEPS LOW-END POPS CONFINED TO THE FAR WEST AND SOUTH SUNDAY. UPPER RIDGE OVER WEST CENTRAL CANADA SUNDAY AND MONDAY WILL TEND TO KEEP MOST OF NORTHERN WYOMING DRY WITH LIGHT FLOW ALOFT...POOR MIXING WITH INVERSIONS AND THE POSSIBILITY OF PATCHY FOG IN THE NORTHERN BASINS. UPPER RIDGE BEGINS TO PROGRESS AND BREAKDOWN TUESDAY AND WEDNESDAY WITH A MORE WESTERLY DIFLUENT FLOW SETTING UP OVER THE REGION. THIS SCENARIO WILL RESULT IN A BETTER CHANCE FOR MORE SIGNIFICANT SNOWFALL ACROSS THE WEST AND BREEZY TO WINDY AND MILDER...BETTER MIXED...CONDITIONS ACROSS CENTRAL WYOMING. AVIATION... SNOWFALL WILL CONTINUE ACROSS MUCH OF WESTERN WYOMING THROUGH THE FORECAST PERIOD. THIS SNOWFALL WILL BRING PERIODS OF MVFR TO IFR CONDITIONS...ESPECIALLY AT KJAC. SNOWFALL RATES WILL INCREASE AFTER 18Z THURSDAY ACROSS THE WEST...WHICH MAY RESULT IN SOME PERIODS OF LIFR CONDITIONS OVER IMPACTED AIRPORTS. AREAS EAST OF THE CONTINENTAL DIVIDE ARE EXPECTED TO REMAIN UNDER MVFR CONDITIONS THROUGH THURSDAY AFTERNOON. CLOUD COVER WILL INCREASE ACROSS THE AREA...BUT SNOWFALL IS EXPECTED TO STAY WEST. MOUNTAIN TOPS WILL BE OBSCURED IN SNOWFALL AND LOW CLOUDS...AND ICING WILL REMAIN POSSIBLE ACROSS THE WESTERN AND SOUTHERN PORTIONS OF THE STATE. FIRE WEATHER... WINDS WILL BE ON THE INCREASE AGAIN THURSDAY INTO THURSDAY NIGHT ACROSS THE WIND CORRIDOR FROM THE RED DESERT TO CASPER AND ALSO IN THE CODY FOOTHILLS. THE WIND WILL ALSO BE ON THE INCREASE ALONG THE EAST SLOPE OF THE WIND RIVER AND BIGHORN MOUNTAINS. THE WEST WILL CONTINUE WITH SNOW. THE SNOW MAY BE HEAVY AT TIMES THURSDAY AFTERNOON THROUGH FRIDAY MORNING. A COLD FRONT WILL SLIDE DOWN EAST OF THE DIVIDE ON FRIDAY. && .RIW WATCHES/WARNINGS/ADVISORIES... HIGH WIND WATCH FROM THURSDAY AFTERNOON THROUGH FRIDAY MORNING WYZ003-015-019. WINTER STORM WATCH FROM THURSDAY MORNING THROUGH FRIDAY MORNING WYZ012-013. && SHORT TERM...SKRBAC LONG TERM...AEM AVIATION...BRANHAM FIRE WEATHER...SKRBAC
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 313 PM MST WED DEC 1 2010 WYZ001>020-022>030-021200- 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 WED DEC 1 2010 ...WINTER STORM WATCH IN MOST OF TETON COUNTY THURSDAY NIGHT AND FRIDAY MORNING... ...HIGH WIND WATCH FOR PORTIONS OF CENTRAL WYOMING THURSDAY NIGHT INTO FRIDAY MORNING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY A STORM SYSTEM COULD BRING THE NEXT ROUND OF SIGNIFICANT SNOWFALL TO FAR WESTERN WYOMING THURSDAY AFTERNOON THROUGH FRIDAY MORNING. SNOWFALL OF 6 TO 12 INCHES ARE POSSIBLE IN THE FAR WESTERN MOUNTAINS WITH HEAVIER AMOUNTS POSSIBLE IN THE TETON MOUNTAINS. THE JACKSON VALLEY MAY SEE 5 TO 9 INCHES WITH 3 TO 6 INCHES IN THE STAR VALLEY. YELLOWSTONE NATIONAL PARK MAY ALSO SEE 6 TO 12 INCHES OF SNOW WITH LOCALLY HIGHER AMOUNTS IN THE SOUTHERN PART OF THE PARK. HIGH WINDS ARE ALSO POSSIBLE IN THE CODY FOOTHILLS...EAST SLOPE OF THE WIND RIVER MOUNTAINS AND THE GREEN MOUNTAINS AND RATTLESNAKE RANGE THURSDAY NIGHT AND EARLY FRIDAY. SOUTHWEST WINDS OF 30 TO 40 MPH WITH GUSTS TO 60 OR 65 MPH ARE POSSIBLE ACROSS THE LOWER ELEVATIONS OF THE WATCH AREA WITH GUSTS UP TO 80 MPH IN THE MOUNTAINS. .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.
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 2010Every state in 2010This day in weather historyWarnings in Wyoming, December 2010
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: 265163.