The combination of a slow moving upper level low passing over Utah and Colorado, powerful jet dynamics, and favorable northerly upslope flow produced very heavy snow across portions of western and central Wyoming. Fremont and Natrona counties were the hardest hit areas.
Every event with a place to put it; 14 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 a slow moving upper level low passing over Utah and Colorado, powerful jet dynamics, and favorable northerly upslope flow produced very heavy snow across portions of western and central Wyoming. Fremont and Natrona counties were the hardest hit areas. Around two feet of snow fell in Lander and the surrounding foothills with 12 to 18 inches around Riverton. The 15.4 inches of snow measured by the cooperative observer in Riverton was the most in a single storm since 1999. In Natrona County, 10 to 18 inches fell in and around Casper with up to 30 inches on Casper Mountain. More impressively, most of the snow in Natrona County fell in a 12-hour period. Widespread snowfall totals of 12 to 20 inches were recorded in the Wind River, Salt River, Wyoming, and Absaroka mountain ranges. The heavy snow, falling temperatures, and gusty wind of 15 to 25 mph combined to close several roads at the height of the storm. These roads included interstates 25 and 90, US Highway 20/26, and State Highway 28 over South Pass.
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 Mar 27, 11:07 PM MST, 53 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE RIVERTON WY 1207 AM MDT MON MAR 28 2016 .UPDATE...UPDATED TO INCLUDE 06Z AVIATION DISCUSSION. && .AVIATION.../06Z ISSUANCE/ WEST OF THE CONTINENTAL DIVIDE...KJAC/KRKS/KPNA/KBPI ROUTES A COLD FRONT WILL DRIVE WIDESPREAD MVFR/IFR -SN INTO THE FAR WEST EARLY MONDAY MORNING...VCNTY AND NORTH OF A KAFO-KPNA LINE BY 10Z...WITH MTNS BECOMING MOSTLY OBSCURED. THERE SHOULD BE SOME IMPROVEMENT ACROSS THE NORTHWEST AFTER 12Z MONDAY AS DRIER AIR PUSHES INTO THE AREA. AN UPPER LOW PRESSURE SYSTEM WILL THEN DIG INTO THE WESTERN GREAT BASIN MONDAY NIGHT WITH RAIN AND SNOW SPREADING FROM SW-NE ACROSS THE AREA MONDAY AFTERNOON AND EVENING. KJAC SHOULD SEE INCREASING DOWNSLOPE NE WINDS AFTER 06Z AND SOME IMPROVEMENT...WHILE WIDESPREAD IFR/MVFR CONDITIONS ARE EXPECTED ACROSS OTHER AREAS SOUTH AND EAST OF KJAC MONDAY NIGHT. EAST OF THE CONTINENTAL DIVIDE...KCPR/KCOD/KRIW/KWRL/KLND ROUTES A COLD FRONT WILL SAG SOUTH INTO NORTHERN WYOMING MONDAY MORNING BRINGING AREAS OF MVFR/IFR -RASN VCNTY AND NORTH OF A KCOD-KGEY LINE BY 12Z MON. THIS FRONT WILL CONTINUE TO PUSH SOUTH SPREADING AREAS OF IFR -SN SOUTH ALONG THE CODY FOOTHILLS...AND MAINLY MVFR -RASN SOUTH ACROSS KWRL-KRIW-KLND 21Z-00Z MON. WIDESPREAD IFR -SN IS EXPECTED TO PREVAIL ACROSS MUCH OF THE AREA 3Z-12Z MONDAY...EXCEPT ACROSS EAST CENTRAL WY WHERE WARMER AIR WILL BRING RAIN OR A RAIN SNOW MIX INTO VCNTY KCPR...THOUGH CIGS ARE STILL EXPECTED TO BE LOW MVFR OR IFR. && .PREV DISCUSSION... /ISSUED 317 PM MDT SUN MAR 27 2016/ SHORT TERM...TONIGHT THROUGH MONDAY WINTER STORM WATCH HIGHLIGHTS EXPANDED EASTWARD FOR TUESDAY OR TUESDAY NIGHT THROUGH WEDNESDAY. WINTER STORM WATCHES REMAIN FOR THE CENTRAL ZONES. WINTER STORM WARNINGS WILL BE ISSUED IN THE SOUTHWEST ZONES FOR MONDAY THROUGH TUESDAY. SPECIAL WEATHER STATEMENT FOR THE REMAINING ZONES NOT INCLUDED IN A HIGHLIGHT. CLOUDS INCREASING IN THE WEST THIS AFTERNOON WITH A CLEAR TO PARTLY CLOUDY SKY EAST OF THE DIVIDE WITH SOME HIGH CLOUDS. BREEZY TO WINDY AREAS IN THE FAVORED WIND PRONE AREAS AND MILD TEMPS. A STORM SYSTEM IS MOVING INTO THE NW U.S. TONIGHT AND THIS WILL BE THE MAIN WEATHER ISSUE FROM LATER TONIGHT THROUGH WEDNESDAY. THE FIRST ROUND OF PRECIP MOVES INTO WESTERN WY LATER THIS EVENING AND CONTINUES INTO MONDAY MORNING. SNOW FOR THE MOUNTAINS WITH SOME SNOW IN THE FAR WEST VALLEYS. THERE LOOKS TO BE BREAK OR LESS INTENSE SNOW MIDDAY MONDAY UNTIL MONDAY NIGHT WHEN THE NEXT ROUND OF SNOW IS EXPECTED. COLDER HIGH TEMPS MONDAY. EAST OF THE DIVIDE...DRY TONIGHT WITH POSSIBLE RAIN OR SNOW SHOWERS IN THE FAR NORTH LATE TONIGHT AS A COLD FRONT DROPS TO THE NORTHERN BORDER AT 12Z MONDAY. ON MONDAY THIS FRONT SAGS SOUTH DURING THE DAY. THE FRONT WILL MOVE INTO THE WIND RIVER BASIN MONDAY AFTERNOON AND TO NEAR CASPER BY 00Z TUE. ISOLATED RAIN SHOWERS WILL OCCUR MONDAY AFTERNOON EAST OF THE DIVIDE. COOLER TEMPS IN THE NORTH MONDAY AND STILL MILD IN THE CENTRAL AND SOUTH. LONG TERM...MONDAY NIGHT THROUGH SUNDAY MOTHER NATURE LOOKS TO BE THROWING A TANTRUM WE HAVE NOT SEEN IN A WHILE WITH A GOOD SNOW STORM FOR MANY PORTIONS OF THE AREA. PRECIPITATION WILL BEGIN SPREADING ACROSS THE AREA MONDAY NIGHT WITH AN INITIAL SHOT OF WARM ADVECTION/OVERRUNNING. WITH FAIRLY MILD TEMPERATURES ON MONDAY...MUCH OF THE EVENING COULD HAVE RAIN UNTIL COLDER AIR AND DYNAMIC COOLING WORK IN AND CHANGE THE RAIN TO SNOW. WITH 700 MILLIBAR FLOW EXPECTED TO TURN EAST TO SOUTHEAST WITH HEAVIEST SNOW MONDAY NIGHT LOOKS TO BE ACROSS THE WIND RIVER BASIN AS WELL AS THE LANDER FOOTHILLS AND AND INTO THE EAST SLOPES OF THE WIND RIVER RANGE AS WELL AS THE EASTERN SALT AND WYOMING RANGE. THE EAST SLOPES OF THE BIG HORN RANGE COULD ALSO SEE SOME SNOW AS WELL AS THE CODY FOOTHILLS. THE LEAST WOULD BE IN THE EASTERN BIG HORN BASIN AS WELL NEAR CASPER AD THE JACKSON ALLEY WITH THE DOWNSLOPING FLOW. THERE IS STILL A BIT OF UNCERTAINTY HOW MUCH SNOW WOULD FALL DURING THE DAY ON TUESDAY THOUGH. THE NAM AND EUROPEAN TAKE THE BEST LIFT NORTH OF THE AREA. IT WILL STILL BE SNOWING...BUT MAYBE NOT AS HARD AS ON MONDAY NIGHT. IN ADDITION...WITH THE STRONG LATE MARCH SUN A LOT OF SNOW COULD MELT OR AT LEAST SETTLED AND LIMIT ACCUMULATION A BIT. AS A RESULT...WE DID CUT BACK QPF A BIT DURING THE DAY TUESDAY. MEANWHILE...ACROSS EASTERN PORTIONS OF THE AREA TEMPERATURES WILL STILL BE BORDERLINE FOR SNOW SO THERE COULD END UP BEING A RAIN/SNOW MIX AND NOT SEE MUCH ACCUMULATION DURING THE DAYLIGHT HOURS. WE DID THE OPPOSITE FOR TUESDAY NIGHT HOWEVER. A DEFORMATION ZONE HAS THE POTENTIAL TO SET UP OVER CENTRAL WYOMING. THIS...COMBINED WITH WINDS TURNING TO A NORTH TO NORTHEASTERLY WIND COULD BRING SOME HEAVY SNOW FROM THE EAST SLOPES OF THE WINDS THROUGH CASPER AND CASPER MOUNTAIN. THE GFS AND ESPECIALLY THE NAM HAVE SOME HEAVY QPF NEAR CASPER WITH THE NAM HAVING NEARLY AN INCH! THIS MAY BE A BIT OVERDONE BUT THIS LOOKS LIKE THE BEST CHANCE FOR HEAVY SNOW FOR NATRONA COUNTY. AS A RESULT...WE UPPED THE QPF FOR TUESDAY NIGHT ACROSS MUCH OF CENTRAL WYOMING. WEDNESDAY SHOULD BE THE WINDING DOWN DAY AS THE STORM MOVES AWAY TO THE SOUTH AND EAST AND SHEARS OUT. CONDITIONS SHOULD IMPROVE FROM NORTH TO SOUTH THROUGH THE DAY ALTHOUGH SOME HEAVIER SNOW COULD LINGER ACROSS CENTRAL WYOMING INTO THE MORNING. WE LOWERED TEMPERATURES SOMEWHAT TO ACCOUNT FOR THE FRESH SNOW. GIVEN THE CONCERNS THROUGH WEDNESDAY...WE DID NOT TAKE A LONG LOOK FROM THURSDAY AND ON. ANOTHER FRONT AND SHORTWAVE WILL ROTATE IN FOR THURSDAY BUT AT THIS POINT IT APPEARS MOISTURE STARVED AND ANY PRECIPITATION AMOUNTS WOULD NOT BE EXCEPTIONAL. DRY WEATHER SHOULD THEN MOVE IN FOR FRIDAY AND INTO THE WEEKEND. ANOTHER SYSTEM MAY MOVE INTO THE WEST SUNDAY BUT FOR NOW WE LEFT CONTINUITY GIVEN MORE IMPORTANT THINGS TO WORRY ABOUT IN THE SHORTER RANGE.&& AVIATION.../00Z ISSUANCE/ WEST OF THE CONTINENTAL DIVIDE...KJAC/KRKS/KPNA/KBPI ROUTES VFR CONDITIONS WILL PREVAIL THROUGH 06Z. ISOLATED TO SCATTERED RAIN AND SNOW SHOWERS WILL OCCUR THROUGH 03Z...THEN INCREASING COVERAGE OF PRECIPITATION THROUGH 12Z. THE JACKSON TERMINAL SITE WILL BE SEE MVFR/IFR CONDITIONS AROUND 06Z AND THIS WILL CONTINUE THROUGH 00Z TUE. THE KPNA/KBPI TERMINAL SITES WILL SEE MVFR CONDITIONS AROUND 12Z MON THROUGH 00Z TUE. KRKS WILL REMAIN VFR THROUGH THE PERIOD. EXPECT THE WESTERN MOUNTAINS TO BE FREQUENTLY OBSCURED LATER TONIGHT THROUGH MONDAY WITH IFR/LIFR CONDITIONS. EAST OF THE CONTINENTAL DIVIDE...KCPR/KCOD/KRIW/KWRL/KLND ROUTES VFR CONDITIONS WILL PREVAIL THROUGH 00Z TUESDAY AT THE TERMINAL SITES. SCATTERED RAIN OR SNOW IS EXPECTED TO OCCUR IN FAR NORTHERN WY TOWARD 12Z WITH LOCAL MVFR CONDITIONS THROUGH 17Z. A COLD FRONT WILL PUSH INTO NORTHERN WY AROUND 12Z MON WITH AREAS OF LOWER CLOUDS FORMING DURING THE DAY MONDAY CREATING LOCAL MVFR CONDITIONS. THIS INCLUDES KBYG AIRPORT. IN CENTRAL WY MONDAY AFTERNOON ISOLATED SHOWERS WILL DEVELOP AFTER 20Z. THE WIND WILL GRADUALLY TURN TO THE NORTH IN CENTRAL WY MONDAY AFTERNOON. FIRE WEATHER... DRY EAST OF THE DIVIDE TONIGHT EXCEPT FOR SOME RAIN OR SNOW SHOWERS IN THE FAR NORTH AFTER MIDNIGHT. IN THE WEST...ISOLATED RAIN AND SNOW SHOWERS WILL OCCUR THIS EVENING. THEN SNOW WILL PREVAIL AFTER MIDNIGHT IN THE WESTERN MOUNTAINS AND FAR WEST VALLEYS. ON MONDAY PERIODS OF SNOW FOR THE WEST THROUGH MONDAY NIGHT INTO TUESDAY. EAST OF THE DIVIDE MONDAY...MOSTLY DRY WITH A SLIGHT CHANCE OF RAIN SHOWERS MONDAY AFTERNOON. RAIN AND SNOW INCREASE MONDAY NIGHT EAST OF THE DIVIDE AND THIS CONTINUES THROUGH TUESDAY. && .RIW WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM THIS EVENING THROUGH WEDNESDAY AFTERNOON FOR WYZ002-003-005-007-015>019. WINTER STORM WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY MORNING FOR WYZ008>011. WINTER STORM WARNING FROM 6 AM THIS MORNING TO 6 PM MDT TUESDAY FOR WYZ014-024. WINTER STORM WARNING FROM NOON TODAY TO 6 PM MDT TUESDAY FOR WYZ025-026. WINTER STORM WARNING FROM 9 AM THIS MORNING TO 6 PM MDT TUESDAY FOR WYZ023-027. WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON FOR WYZ020-022. && SHORT TERM...AR LONG TERM...HATTINGS AVIATION...AEM FIRE WEATHER...AR
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE RIVERTON WY 502 PM MDT SUN MAR 27 2016 WYZ001>020-022>030-281200- 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- 502 PM MDT SUN MAR 27 2016 ...WINTER STORM WARNINGS FOR PARTS OF WEST AND SOUTHWEST WYOMING MONDAY THROUGH TUESDAY AFTERNOON... ...WINTER STORM WATCHES FOR PORTIONS OF CENTRAL WYOMING MONDAY NIGHT THROUGH WEDNESDAY AFTERNOON... THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT SNOW OCCURS OVER THE WESTERN MOUNTAINS TONIGHT. AREAS OF SNOW IN THE FAR WEST VALLEYS AROUND MIDNIGHT OR AFTER MIDNIGHT. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY WEST OF THE DIVIDE...SIGNIFICANT SNOWFALL MONDAY THROUGH TUESDAY. EAST OF THE DIVIDE...SIGNIFICANT SNOW EXPECTED AS EARLY AS MONDAY NIGHT...ACROSS THE WIND RIVER BASIN AND THE CODY FOOTHILLS AS WELL AS OVER THE ADJACENT MOUNTAINS. THEN SNOW WILL EXPAND TO THE BIGHORN MOUNTAINS AND TO JOHNSON AND NATRONA COUNTIES TUESDAY OR TUESDAY NIGHT THROUGH WEDNESDAY AFTERNOON. .SPOTTER INFORMATION STATEMENT... SPOTTER ARE ENCOURAGED TO REPORT ANY SNOWFALL AMOUNTS. THANK YOU. TEAM RIVERTON
The national radar mosaic for the moment the first event began.
14 winter storm. Local standard time, as filed.
Trained spotters reported 6-8 inches of snowfall throughout the Star Valley.
The SNOTEL at Indian Creek measured 22 inches of new snow. The Kelly Ranger Station had 12 inches of new snow.
Heavy snow fell across the Upper Wind River basin with common totals of 6 to 9 inches.
Several SNOTEL sites in the southeastern Bighorn Mountains recorded over a foot of new snow. The highest snowfall total was 14 inches at Cloud Peak.
Very heavy snow fell along the east slopes of the Wind River Range. Some of the heaviest amounts include 32 inches at the Hobbs Creek SNOTEL and 23 inches at Bruce's Campground in Sinks Canyon State Park.
Heavy snow fell in portions of the Absarokas. Some of the heaviest amounts included 19 inches at the Marquette and Kirwin SNOTEL sites.
Route 28 over South Pass was closed for over 18 hours due to heavy snow and blowing snow.
Very heavy snow fell in the Lander Foothills. One to two feet was commonplace with an official measurement of 19.4 inches at the Lander airport.
A trained spotter measured 10 inches of snow at Jeffrey City.
At the Riverton airport 16 inches of snow was measured. Around Riverton, 12 to 18 inches of snow was measured. Lighter amounts fell in Shoshoni where only 2.4 inches was measured.
Around Thermopolis 6 to 8 inches of snow was measured.
Snowfall of 7.5 inches was recorded 2 miles southwest of Cody.
Heavy snow fell throughout Natrona County, with highest amounts in the foothills of Casper Mountain. Total amounts ranged from 6 inches at Midwest, to 10.8 inches at the Casper airport, to 18 inches along Outer Drive.
A trained spotter measured 30 inches of snow on Casper Mountain. The SNOTEL estimated 22 inches of new snow.
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, March 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: 618214, 618213, 618216, 618359, 618215, 618219, 618212, 618218, 618220, 618217, 618222, 618221, 618360, 618361.