An area of low pressure moved out of the Great Basin and passed across Colorado with another low developing in the lee of the Rockies. With ample Pacific moisture available, heavy snow fell across much of Sweetwater and Natrona counties.
Every event with a place to put it; 5 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS RIW wrote it up.
An area of low pressure moved out of the Great Basin and passed across Colorado with another low developing in the lee of the Rockies. With ample Pacific moisture available, heavy snow fell across much of Sweetwater and Natrona counties. The heaviest snow fell around Casper where favorable north to northeast low-level upslope flow brought over a foot of snow to parts of the city. Nearby Casper Mountain received as much as two feet of snow. Heavy snow also fell in Sweetwater County where reports of 5 to 10 inches were common. The snow was accompanied by occasional wind gusts over 40 mph, which reduced visibility and created treacherous road conditions. This combination of snow and wind led to the closure of Interstate 80.
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 31, 11:11 PM MST, 49 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RIVERTON WY 1111 PM MST SUN JAN 31 2016 .SHORT TERM...TONIGHT THROUGH MONDAY ISSUED WINTER WEATHER ADVISORY FROM MONDAY MORNING THROUGH TUESDAY MORNING FOR SNOW AND BLOWING SNOW ACROSS NATRONA... FREMONT...SWEETWATER AND SOUTHERN LINCOLN COUNTIES. CENTRAL AND SOUTHERN WYOMING WILL BE ON THE NORTHWEST EDGE OF A LARGE WINTER STORM THAT WILL BE MOVING THROUGH THE SOUTHERN AND CENTRAL ROCKIES MONDAY AND MONDAY NIGHT. NATRONA...FREMONT... SWEETWATER AND SOUTHERN LINCOLN COUNTIES ARE EXPECTED TO SEE SNOW DEVELOP MONDAY MORNING WITH BRISK NORTHEAST WINDS. BY MONDAY AFTERNOON SIGNIFICANT SNOW AND BLOWING SNOW IS EXPECTED. THE SNOW AND BLOWING SNOW SHOULD CONTINUE THROUGH MONDAY NIGHT AND TAPER OFF TUESDAY MORNING. TO THE NORTH SCATTERED SNOW SHOWERS ARE EXPECTED WITH COLDER TEMPERATURES. .LONG TERM...MONDAY NIGHT THROUGH SUNDAY BY EARLY MONDAY EVENING THE SNOWFALL WILL CONTINUE MAINLY SOUTH OF A LINE FROM KMM TO FT WASHAKIE...RIW AND TO KAYCEE AS THE ISENTROPIC LIFT CONTINUES TO PENETRATE NORTH TO THIS LINE ALONG WITH SOME Q VECTOR FORCING. THESE DYNAMICS WILL SEED THE LOWER DECK OF STRATOCU IN PLACE THAT WILL BE ASCT WITH THE LOW LEVEL UPSLOPE FLOW AFFECTING THE AREA FROM LND TO CPR. BY 00Z TUE...THE MAIN LOW WILL BE UNDERGOING CYCLOGENESIS OVER SE COLORADO AND WILL BECOME MORE OR LESS VERTICALLY STACKED. THE INFLUENCE OF THE STRONG CYCLONIC FLOW AROUND THE BACKSIDE OF THE LOW WILL STILL BE ENCOMPASSING THESE AFOREMENTIONED AREAS. SNOW AND BLOWING SNOW WILL CONTINUE IN THESE REGIONS IN THE ADVISORY THROUGH MONDAY NIGHT WITH SNOW TOTALS OF UP TO 4 INCHES IN LANDER AND CASPER BY 15Z TUESDAY ALONG WITH 1 TO 2 INCHES IN RIVERTON...UP TO 6 INCHES ON THE EAST SLOPE OF THE WIND RVR MTNS AND 8 INCHES ON CASPER MTN. AREAS JUST TO THE NORTH OF RIVERTON SHOULD SEE VERY LITTLE IN THE WAY OF SNOWFALL DUE TO BEING TOO FAR NORTH OF THE DYNAMICS AND THE OWL CREEK MTN SNOW SHADOW EFFECT. THE UPPER GREEN RVR BASIN WILL GET SHADOWED BY THE WIND RVR MTNS AS WELL. WINTER WEATHER ADVISORIES WILL BE IN EFFECT TIL 15Z TUESDAY. BY 15Z TUE...THE LOW WILL BE WAY OUT OVER CENTRAL KANSAS BUT THERE SHOULD BE ENOUGH LIGHT SNOWFALL AND LINGERING BLOWING SNOW TO WARRANT HAVING THE ADVISORY EXTEND THROUGH THE RUSH HOUR FOR THOSE SOUTH AND SOUTHEAST ZONES. THEN BY TUESDAY AFTERNOON...OUR ATTENTION WILL SHIFT TO WESTERN WY WHERE A SHORTWAVE TROUGH RIDING DOWN THE BACK SIDE OF THE MAIN EXITING TROUGH WILL CAUSE THE FLOW TO BECOME INCREASINGLY DIFLUENT FROM THE NNW WITH SNOWFALL INCREASING IN FAR WESTERN WY BY LATE TUESDAY AFTERNOON. SNOWFALL WILL CONTINUE TUESDAY NIGHT THROUGH WEDNESDAY IN THE WEST. A BIT TOO EARLY TO FINE TUNE SNOW AMNTS WITH THIS FEATURE FOR NOW. THEN BEHIND THIS SHORTWAVE...TEMPS WILL BEGIN TO WARM AS THE JET STREAM SHIFTS TO OUR NORTHEAST. A TEMPERATURE INVERSION SHOULD BE IN PLACE BY 12Z WED IN THE VALLEYS AND BASINS BUT ELECTED TO HOLD OFF ON MENTION OF PATCHY FOG IN THE WIND RIVER BASIN FOR NOW IN SPITE OF THE FRESH SNOW COVER AS FCST SOUNDINGS ARE NOT IDEAL FOR THAT TIME FRAME. THE NEXT SHORTWAVE IN THE NW FLOW WILL GIVE THE FAR WEST MORE SNOWFALL THURSDAY THROUGH FRIDAY. THEN ANOTHER...MORE VIGOROUS SHORTWAVE TROUGH...THAT WILL BE ASCT WITH A STRONG NW DIFLUENT FLOW...WILL SWING A 700MB COLD FRONT NOSING RIGHT INTO CENTRAL WY LATER SATURDAY...WHICH TENDS TO BE AN INDICATION THAT CENTRAL WY EAST OF THE DVD COULD GET SOME PRECIP ACDG TO THE GFS BUT WE WILL HAVE TO WAIT FOR MORE RUN TO RUN CONSISTENCY. THE ECMWF TAKES THIS FEATURE FARTHER SOUTH. THE GFS HAS THE TROUGHPA SAY NT AND THE ECMWF SUNDAY...SO AGAIN...WE WILL WAIT FOR A BIT MORE CONSISTENCY TO MAKE ANY WHOLE SALE CHANGES TO THE POP/SNOWFALL GRIDS FOR NEXT WEEKEND. && .AVIATION.../06Z ISSUANCE/ RAPIDLY DETERIORATING CONDITIONS FROM SOUTH TO NORTH MONDAY MORNING AS A LARGE WINTER STORM IMPACTS THE CENTRAL AND SOUTHERN ROCKIES. WIDESPREAD IFR CONDITIONS IN VSBY REDUCTIONS IN SNOW ARE EXPECTED TO DEVELOP MONDAY MORNING...AND REMAIN FOR MUCH OF THE TAF FORECAST PERIOD ALONG AND SOUTHEAST OF KEMM-KLND-KBYG LINE. ALSO STRONG NORTH TO NORTHEAST WINDS WILL OCCUR IN MUCH OF THE SAME AREA CAUSING CONSIDERABLE BLOWING SNOW. AIRFIELD MINIMUMS COULD OCCUR FOR SEVERAL HOURS AT KRKS DUE TO VSBY RESTRICTIONS IN SN AND BLSN WITH THE BEST CHANCE BETWEEN 19Z AND 01Z. ALSO CPR COULD ALSO SEE AIRFIELD MINIMUMS...BUT CONFIDENCE IS NOT AS HIGH AS KRKS. HAVE KEPT BOTH TERMINALS JUST ABOVE AIRFIELD MINIMUMS FOR NOW. KPNA MAIN ISSUE WILL BE LOW LEVEL WIND SHEAR FROM THE NORTHEAST TODAY...AS DOWNSLOPING SHOULD KEEP THEM DRY. KJAC TERMINAL WILL BE LEAST IMPACTED FROM THIS SYSTEM WITH ONLY SOME SNOW SHOWERS IMPACTING THE AREA...WITH VFR CONDITIONS EXPECTED WITH A BREEZY FROM THE NORTH. PLEASE SEE THE AVIATION WEATHER CENTER FOR THE LATEST INFORMATION ON ICING AND TURBULENCE FORECASTS. && .FIRE WEATHER... ISSUED WINTER WEATHER ADVISORY FROM MONDAY MORNING THROUGH TUESDAY MORNING FOR SNOW AND BLOWING SNOW ACROSS NATRONA... FREMONT...SWEETWATER AND SOUTHERN LINCOLN COUNTIES. CENTRAL AND SOUTHERN WYOMING WILL BE ON THE NORTHWEST EDGE OF A LARGE WINTER STORM THAT WILL BE MOVING THROUGH THE SOUTHERN AND CENTRAL ROCKIES MONDAY AND MONDAY NIGHT. NATRONA...FREMONT... SWEETWATER AND SOUTHERN LINCOLN COUNTIES ARE EXPECTED TO SEE SNOW DEVELOP MONDAY MORNING WITH BRISK NORTHEAST WINDS. BY MONDAY AFTERNOON SIGNIFICANT SNOW AND BLOWING SNOW IS EXPECTED. THE SNOW AND BLOWING SNOW SHOULD CONTINUE THROUGH MONDAY NIGHT AND TAPER OFF TUESDAY MORNING. TO THE NORTH SCATTERED SNOW SHOWERS ARE EXPECTED WITH COLDER TEMPERATURES. HIGH RELATIVE HUMIDITY WITH LOW MIXING HEIGHTS AND POOR SMOKE DISPERSAL IS EXPECTED THROUGH TUESDAY. && .RIW WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 9 AM MONDAY TO 9 AM MST TUESDAY FOR WYZ015-018>020-022-027>030. && SHORT TERM...C.BAKER LONG TERM...LIPSON AVIATION...WM FIRE WEATHER...C.BAKER
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 101 PM MST SUN JAN 31 2016 WYZ001>020-022>030-012015- 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- 101 PM MST SUN JAN 31 2016 THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. ...WINTER WEATHER ADVISORIES HAVE BEEN ISSUED FOR NATRONA... FREMONT...SWEETWATER AND SOUTHERN LINCOLN COUNTIES MONDAY INTO TUESDAY MORNING... .DAY ONE...THIS AFTERNOON AND TONIGHT SNOW IS EXPECTED TO DEVELOP ACROSS NATRONA...SWEETWATER...FREMONT AND SOUTHERN LINCOLN COUNTIES WITH INCREASING NORTHEAST WINDS LATE TONIGHT. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY SNOW AND BLOWING SNOW IS EXPECTED ACROSS NATRONA...SWEETWATER...FREMONT AND SOUTHERN LINCOLN COUNTIES WITH INCREASING NORTHEAST WINDS OF 25 TO 35 MPH WITH STRONGER GUSTS. TO THE NORTH AND WEST OF THESE COUNTIES STRONG WIND WITH AREAS OF LIGHT SNOW CAN BE EXPECTED. WEDNESDAY AND THURSDAY WILL BE COLDER WITH BELOW ZERO LOWS IN THE WESTERN VALLEYS. THERE IS A CHANCE OF MORE SNOW BY FRIDAY. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE URGED TO REPORT SNOWFALL AMOUNTS. THANK YOU. TEAM RIVERTON
The national radar mosaic for the moment the first event began.
5 winter storm. Local standard time, as filed.
Heavy snow fell in portions of the area. Between 5 and 8 inches of snow were measured across Green River. In addition, Interstate 80 was closed for several hours due to snow and blowing snow.
A trained spotter reported 10 inches of snow at the Buckboard Marina.
The cooperative observer in Wamsutter measured 10 inches of snow. In addition, the combination of snow and blowing snow closed Interstate 80 and other area roads for several hours.
A trained spotter measured 24 inches of new snow on Casper Mountain. SNOTEL sites on the mountain estimated from 12 to 21 inches of snow.
Heavy snow fell across much of Natrona County, with the highest amounts closer to Casper Mountain. Amounts ranged from 6 inches at Midwest, to 12.5 inches at the Casper Airport, to 13 inches in south Casper near the foothills.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2016Every state in 2016This day in weather historyWarnings in Wyoming, February 2016
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: 610075, 610076, 610077, 610074, 610073.