The combination of ample Pacific moisture, good upper level divergence and an approaching Arctic Front brought heavy snow to many portions of western and central Wyoming. The heaviest snow fell in the western Mountains where many locations eclipsed 2 feet of new snow, with the highest amount of 32 inches at Lewis Lake Divide in Yellowstone Park.
Every event with a place to put it; 13 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.
The combination of ample Pacific moisture, good upper level divergence and an approaching Arctic Front brought heavy snow to many portions of western and central Wyoming. The heaviest snow fell in the western Mountains where many locations eclipsed 2 feet of new snow, with the highest amount of 32 inches at Lewis Lake Divide in Yellowstone Park. Meanwhile, East of the Divide, the heaviest snow fell around the Cody area, where over a foot of snow was common. The snow was accompanied by gusty winds that brought blowing and drifting snow that closed many roads for a time, including Interstate 25 in the vicinity 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 14, 11:11 AM MST, 3 hours 49 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1111 AM MST Wed Dec 14 2016 .SHORT TERM...Today through Friday night The first surge of Pacific moisture is beginning to move into far western WY this morning, stretching into southern portions of the Pacific near 20N lat. This moisture is expected to continue across western portions through the day today, as a warm front begins to lift toward from northern UT. Light showers have developed over northern UT and will expand northward through the day today. This precipitation is expected to stay west of the Divide during the day today, before sliding eastward along the warm front. An arctic boundary that penetrated northern and central portions east of the Divide Tuesday night will remain in place over these areas during the day today. Overrunning precipitation is expected tonight east of the Divide, with only light snow accumulations expected. The plume of moisture will persist over NW WY tonight into Thursday, as areas east of the Divide mix out early Thursday morning. H7 winds of 50-60kt over the Wind River Mountains are progged again, which will aid in the mixing of those winds to the surface and warm temperatures into the lower to middle 40s. A surface low is still progged to form somewhere near northern portions of the Wind River Basin or southern portions of the Big Horn Basin. The lee side cyclogenesis of this low on Thursday will be key to how far north the warm air invades. Precipitation will re-enter southwestern portions late Thursday afternoon into the overnight hours, as embedded shortwaves move over southern ID/OR. A developing surface low will form over SE ID by 12Z, which will aid in the precipitation across southern portions Thursday night. The aforementioned arctic boundary will retreat to northern WY by Thursday, before surging southward once again early Friday morning. Precipitation will form along this boundary as well, bringing widespread snow east of the Divide through the day on Friday. This system will finally begin to exit the state by 00z Saturday, with dry, arctic air invading the forecast area and quickly ending the snow. Once again have several forecast challenges for this package. The first will be the chances for precipitation across southwestern WY behind the warm front Wednesday night into Thursday. This will include the Star Valley and the Salt and Wyoming Ranges. For now, have left scattered to numerous PoPs in these areas. This also includes the possibility for the warm, southerly winds to warm the Star Valley above freezing and introduce a rain/snow mix to the valley. The second challenge will be the extent of the winds Thursday, especially for the Lander Foothills. Have kept them out of the High Wind Watch due to H7 winds staying westerly. Have 50/50 confidence with respect to snow amounts at KDUB. 1 to 2 inches could fall Wednesday night, before subsiding to flurries on Thursday. This will be under the southwest flow, before turning northerly behind the arctic front. Confidence has lowered a bit for enough upslope flow and moisture to reach that far up the Wind River Basin in this pattern, but have issued a long-fuse Advisory to cover both sides of the event. .LONG TERM...Saturday through Wednesday The major winter storm in the short term will be down to some very light snow or flurries Saturday morning with a quick drying trend expected. Although the snowfall has ended, the bitter cold temperatures will remain for at least a few days. Temperatures Saturday and Sunday will be 20 to 30 degrees below average with highs struggling to even get above zero in a few spots. A warming trend is expected early next week especially in the mountains and typical mixed (windy) lower elevations. Could see some fog formation in trapped basins Sunday night and/or Monday night, but confidence not high enough to put into the weather grids this far out. Medium range models then show a shortwave trough in the northwest flow impacting the area in the Tuesday/Wednesday time frame. Last night both of them had this system impacting the area Tuesday, while 00Z runs tonight have the ECMWF keeping about the same timing while the GFS does not have this feature impacting the area until late Wednesday into next Thursday. && .AVIATION.../18Z Issuance/ West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals Light snow along the I-80 corridor from KEVW to KRKS late this morning. IFR conditions expected off-and-on through the afternoon at KRKS. This warm-frontal type snow band will lift north later this afternoon and early this evening. MVFR to IFR conditions will persist from 00Z-06Z/Thu at KBPI and KPNA, while the snow will begin to decrease between 00Z-03Z/Thu at KRKS. These three terminals should improve to at least low-end VFR after 06Z/Thu with those conditions continuing through 18Z/Thu. At KJAC, the snow is expected to pick-up again this afternoon with little let-up through the rest of the foreast period. IFR/LIFR conditions expected after 00Z/Thu with occasional improvement to MVFR. Mountain obscurations, especially across northwest Wyoming, will be widespread. Expect southwest wind to increase late tonight. While the strongest winds are not likely to reach the surface, the stage is set for LLWS in the lowest 1,000 to 1,500 feet. Enough wind at KJAC Thursday morning to produce BLSN and LIFR visibilities. East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals VFR conditions are anticipated through about 01Z/Thu before snow band associated with north-moving warm front moves across central Wyoming. Looks difficult to get much snow or MVFR conditions at KRIW and KLND as this wave lifts north. However, it does appear KCPR will fare better between about 02Z-08Z/Thu with the best chance between 04Z-07Z/Fri. Have IFR conditions during this 6-hour period. Wave continues to lift north through KWRL and KCOD with MVFR and IFR conditions possible, respectively. Wave should clear these terminals by 10Z/Thu. Mountain obscurations will be frequent during the 02Z- 10Z timeframe. Also expect southwest wind to increase late tonight. While the strongest winds are not likely to reach the surface except at KCPR, the stage is set for LLWS in the lowest 1,000 to 1,500 feet. Have 20-30kt winds in KCPR forecast by 12Z/Thu and continuing through 18Z/Thu. && .FIRE WEATHER... Snow will develop out across the west today and continue through Friday with significant accumulation. An arctic cold front will hover around Central Wyoming today before lifting north tonight. Strong southwest wind will develop along the lee of the Wind River Mountains and wind corridor from Jeffrey City to near Casper late tonight through Thursday. Some brief snow will fall east of the divide Wednesday night. More significant snow and bitterly cold air will arrive Friday. && .RIW WATCHES/WARNINGS/ADVISORIES... High Wind Watch from this evening through Thursday afternoon for WYZ015-019. Winter Storm Watch from late Thursday night through Friday evening for WYZ003>007-010-011-015-017>020-022. Winter Storm Warning from noon today to 5 PM MST Friday for WYZ001-002-012>014-024-025. Winter Weather Advisory from 5 PM this afternoon to midnight MST Friday night for WYZ016. Winter Weather Advisory from noon today to 5 PM MST Friday for WYZ023. Winter Storm Watch from this evening through Friday evening for WYZ008-009. && SHORT TERM...LaVoie LONG TERM...WM AVIATION...CNJ FIRE WEATHER...LaVoie
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 215 PM MST WED DEC 14 2016 WYZ001>020-022>030-151200- 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- 215 PM MST WED DEC 14 2016 ...NUMEROUS WINTER STORM AND HIGH WIND PRODUCTS FOR A MAJOR WINTER STORM IMPACTING THE WEST THIS AFTERNOON THROUGH FRIDAY, AND THE EAST MAINLY THURSDAY NIGHT INTO FRIDAY NIGHT... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT SIGNIFICANT SNOW DEVELOPING OVER WESTERN WYOMING THIS AFTERNOON AND BECOMING MORE WIDESPREAD AND HEAVIER THIS EVENING. STRONG TO HIGH WINDS OVER THE EASTERN SLOPES OF THE WIND RIVER MOUNTAINS AND SOUTHEAST FREMONT COUNTY. PLEASE SEE THE WINTER WEATHER AND HIGH WIND PRODUCTS FOR MORE DETAILS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THURSDAY AND FRIDAY...SIGNIFICANT WINTER STORM CONTINUES OVER WESTERN WYOMING. AN ARCTIC COLD FRONT WILL DROP SOUTH...EAST OF THE DIVIDE THURSDAY NIGHT. THIS WILL RESULT IN SHARPLY COLDER AIR AND THE POTENTIAL FOR SIGNIFICANT SNOWFALL IN SOME LOCATIONS EAST OF THE DIVIDE LATE THURSDAY NIGHT THROUGH MUCH OF FRIDAY NIGHT. HIGH WINDS CONTINUE OVER THE EAST SLOPE OF THE WIND RIVER...GREEN MOUNTAINS AND RATTLESNAKE RANGE THROUGH THURSDAY EVENING. SATURDAY AND SUNDAY...BITTERLY COLD...WITH TEMPERATURES 20 TO 30 DEGREES BELOW AVERAGE. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE ENCOURAGED TO REPORT ANY SNOWFALL BY CALLING 1-800-211-1448.
The national radar mosaic for the moment the first event began.
13 winter storm. Local standard time, as filed.
Heavy snow fell in northern portions of this zone with 17 inches of snow in Bondurant and 9 inches at Daniel. Further south, the snow mixed with rain and held accumulaitons down with only 3 inches at Pinedale.
Very heavy snow fell in Yellowstone Park. Some of the higher amounts included 32 inches at the Lewis Lake Divide SNOTEL and 30 inches at the Snake River Ranger Station.
Heavy snow though portions of the Jackson Valley. Amounts ranged from 4 inches in Jackson to 19 inches near Wilson.
Heavy snow fell throughout the Salt and Wyoming Range. Some of the largest accumulations were 25 inches at the Blind Bull Summit and Indian Creek SNOTEL sites.
Heavy snow fell in the Absarokas. Some of the higher amounts included 27 inches at the Beartooth Lake SNOTEL and 24 inches at the Blackwater Lake SNOTEL.
Heavy snow fell through the Tetons and Gros Ventres. The highest amount was 31 inches, which fell at Jackson Hole Ski Resort and the Grassy Lake SNOTEL.
The Gunsite Pass SNOTEL recorded 15 inches of new snow.
Heavy snow fell in the Cody Foothills. The highest amounts were around Wapati where 27 inches of new snow fell. Over a foot of new snow was common across the city of Cody.
Heavy snow fell in and around Lovell where 8 to 11 inches of snow occurred. Lesser amounts fell further south.
Heavy snow fell through the east slopes of the Wind River Range. Some of the highest amounts included 28 inches at the South Pass SNOTEL and 18 inches at Atlantic City.
Trained spotters measured anywhere from 6 to 10 inches across the city of Buffalo.
The Casper Mountain SNOTEL recorded 12 new inches of snow.
Across the city of Casper, 6 to 10 inches of new snow occurred. The snow was accompanied by gusty winds that brought blowing and drifting snow, closing Interstate 25 and US 20 26 for several hours.
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, December 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: 665916, 665910, 665913, 665914, 665911, 665912, 665915, 665917, 665918, 665922, 665919, 665921, 665920.