Storng westerly flow aloft brought a brief Pacific storm to western Wyoming. Snowfall amounts ranged from 6 to 12 inches.
Every event with a place to put it; 3 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.
Storng westerly flow aloft brought a brief Pacific storm to western Wyoming. Snowfall amounts ranged from 6 to 12 inches. Wind gusts of 60 to 80 mph were recorded by automatic sensors.
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 Feb 7, 2:22 PM MST, 10 hours 38 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
222 PM MST THU FEB 7 2002
MID/HIGH CLOUDS CONTINUE TO STREAM EAST ACROSS THE CWFA AT 21Z.
OBSERVATIONS NOT DETECTING MUCH BELOW 12K FT MSL. WIND SPEEDS
GENERALLY 20 TO 35 MPH AT FAVORED LOCATIONS. WELL-DEFINED SHORTWAVE
SEEN ON WATER VAPOR LOOP APPROACHING THE OREGON COAST. THIS WAVE
BEING EJECTED FROM UPPER LOW SITUATED AROUND 50N/135W. THIS WILL BE
THE MAJOR WEATHER MAKER AND CONCERN THROUGH FRIDAY NIGHT. MAIN ISSUES
TO ADDRESS ARE SNOWFALL AMOUNTS AND TIMING OF CLEARING ON SATURDAY.
CROSS SECTIONS INDICATE THAT DEPTH OF MOISTURE INCREASES
SIGNIFICANTLY OVER THE WEST BEGINNING TONIGHT...ESPECIALLY AFTER
MIDNIGHT. STRONG WESTERLY FLOW WILL INCREASE TO 40-50 KTS LATE
TONIGHT AND EARLY FRIDAY MORNING. HOWEVER...TROUGH PASSAGE OCCURS
OVER THE WEST BY MIDDAY FRIDAY AND BEST DIV-Q REMAINS NORTH OF THE
CWFA. THUS...WITH LIMITED DYNAMICS BEST CHANCE FOR ACCUMULATING SNOWS
WILL ONLY BE THE 12 HOUR PERIOD FROM 06Z-18Z/FRI. BELIEVE THAT THE
MAIN CAUSE FOR SNOWFALL WILL BE OROGRAPHICS WITH 80%+ RH THROUGH
500MB...7/5 LYR LAPSE RATES IN THE 7-8C/KM RANGE AND STRONG 700 MB
WINDS. SURFACE WINDS IN THE WESTERN VALLEYS WILL ALSO INCREASE FROM
THE SSW LATE TONIGHT. WITH ALL OF THIS IN MIND WILL ISSUE WINTER WX
ADV FOR MUCH OF THE WEST LATE TONIGHT AND FRIDAY. BELIEVE THAT
SNOWFALL AMOUNTS WILL BE AT THE LOW END OF ADVISORY CRITERIA...BUT
THAT WIND AND BLOWING SNOW WILL BE SIGNIFICANT ENOUGH TO WARRANT
HIGHLIGHTS. EAST HALF OF THE CWFA WILL SEE COOL DOWN AND A SHIFT TO
NORTHWEST WINDS FRIDAY AFTERNOON AS FRONTAL BOUNDARY SWEEPS THROUGH.
THIS WILL FAVOR INCREASED WIND IN THE RIW CORRIDOR AND BIG HORN
BASIN. BYG AREA BEARS WATCHING FOR STRONG POST FRONTAL WINDS LATE
FRIDAY AND FRIDAY EVENING. LOWER ATMOSPHERIC FLOW NEVER BECOMES NORTH
OR NORTHEAST...SO SNOWFALL WILL BE LIMITED IN NATRONA AND JOHNSON
COUNTIES. 500MB COLD POOL OF -34C WILL DRIFT ACROSS THE AREA FRIDAY
NIGHT AND EARLY SATURDAY MORNING. THIS CONVECTIVE ELEMENT WILL HELP
ENHANCE SNOW SHOWERS INTO SATURDAY MORNING OVER THE EAST HALF.
DEFORMATION AXIS WILL SHIFT EAST OF THE CWFA ON SATURDAY AFTERNOON AS
TROUGH DIGS IN THE CENTRAL PLAINS. DRY AND MOSTLY SUNNY CONDITIONS
WILL THEREFORE SPREAD FROM WEST TO EAST DURING THE MORNING AND EARLY
AFTERNOON. DRY SURFACE HIGH TO THEN ENTRENCH ITSELF OVER THE AREA
WITH UPPER RIDGE BUILDING IN THE GREAT BASIN. DRIER AND LESS WINDY
CONDITIONS EXPECTED FOR SUNDAY.
IN THE EXTENDED...ALL MODELS QUITE SIMILAR THROUGH TUESDAY.
SHORTWAVE WILL PASS NORTH ACROSS THE NORTHERN ROCKIES ON MONDAY.
LEE TROUGH LOOKS TO BE SETTING UP...SO WILL WORD FOR BREEZY/WINDY
CONDITIONS OVER THE EAST. THIS LOOKS TO BE THE WARMEST DAY OF THE
PERIOD. THE SHORTWAVE WILL THEN DIVE INTO THE NORTHERN PLAINS
TUESDAY ALLOWING FOR A MORE ZONAL FLOW ACROSS WYOMING. SURFACE HIGH
REMAINING OVER THE INTERMOUNTAIN WEST WILL PROVIDE DRY CONDITIONS.
BETTER ORGANIZED TROUGH EXPECTED TO TRAVERSE THE STATE ON
WEDNESDAY...SO WILL ISSUE CHANCE POPS MOUNTAINS AND WEST WITH SLIGHT
CHANCE LOWER ELEVATIONS. COOLER TEMPERATURES WILL FOLLOW BEHIND
THIS FEATURE ON THURSDAY...BUT DRYING CONDITIONS ARE EXPECTED WITH
SHORTWAVE RIDGE IN PLACE. CNJ
.RIW...WINTER WEATHER ADVISORY LATE TONIGHT AND FRIDAY
WY ZONES 1>3...6...7...16...17.The national radar mosaic for the moment the first event began.
3 winter storm. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2002Every state in 2002This day in weather historyWarnings in Wyoming, February 2002
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: 5283262, 5283263, 5283264.