A fast moving Pacific storm system brought moderate to heavy snowfall and gusty westerly winds of 35 to 45 mph to the Snowy and Sierra Madre ranges. Snow totals were estimated between 6 and 12 inches.
Every event with a place to put it; 7 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 CYS wrote it up.
A fast moving Pacific storm system brought moderate to heavy snowfall and gusty westerly winds of 35 to 45 mph to the Snowy and Sierra Madre ranges. Snow totals were estimated between 6 and 12 inches. Blowing snow and reduced visibilities caused hazardous travel for mountain passes.
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 Cheyenne, WY wrote its last area forecast discussion before the first event at Apr 12, 5:41 PM MST, 2 hours 19 minutes earlier.
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</html>HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHEYENNE WY 912 AM MDT FRI APR 12 2013 NEZ002-003-019>021-054-055-095-096-WYZ102-131515- DAWES-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-KIMBALL-CHEYENNE- NORTH SIOUX-SOUTH SIOUX-NIOBRARA COUNTY- 912 AM MDT FRI APR 12 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA PANHANDLE AND EAST CENTRAL WYOMING. .DAY ONE...TODAY AND TONIGHT RAIN AND SNOW SHOWERS LOOK LIKELY TODAY...PARTICULARLY FOR THE SOUTHERN PANHANDLE SOUTH OF A LINE FROM ALLIANCE TO SCOTTSBLUFF. SIGNIFICANT ACCUMULATIONS ARE NOT EXPECTED...BUT ROADS COULD BECOME SLICK IN AREAS IF HEAVIER SNOW SHOWERS PASS OVER A PARTICULAR STRETCH OF ROAD. USE CAUTION IF TRAVELING THIS MORNING AND AFTERNOON. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY WINDY CONDITIONS ARE EXPECTED ACROSS MUCH OF THE AREA SUNDAY. A SLOW MOVING LOW PRESSURE SYSTEM IS EXPECTED TO AFFECT THE AREA MONDAY THROUGH WEDNESDAY BRINGING RAIN AND SNOW. SIGNIFICANT ACCUMULATING SNOWS ARE POSSIBLE ESPECIALLY OVER HIGHER TERRAIN. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT. && THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC...AND CLIMATE INFORMATION IS AVAILABLE ON THE WEB AT... HTTP://WEATHER.GOV/CHEYENNE WYZ101-103>119-131515- CONVERSE COUNTY LOWER ELEVATIONS-NORTH LARAMIE RANGE- FERRIS/SEMINOE/SHIRLEY MOUNTAINS-SHIRLEY BASIN- CENTRAL LARAMIE RANGE AND SOUTHWEST PLATTE COUNTY- EAST PLATTE COUNTY-GOSHEN COUNTY-CENTRAL CARBON COUNTY- NORTH SNOWY RANGE FOOTHILLS-SOUTHWEST CARBON COUNTY- SIERRA MADRE RANGE-UPPER NORTH PLATTE RIVER BASIN-SNOWY RANGE- LARAMIE VALLEY-SOUTH LARAMIE RANGE-SOUTH LARAMIE RANGE FOOTHILLS- CENTRAL LARAMIE COUNTY-EAST LARAMIE COUNTY- 912 AM MDT FRI APR 12 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST CENTRAL WYOMING... SOUTH CENTRAL WYOMING AND SOUTHEAST WYOMING. .DAY ONE...TODAY AND TONIGHT A FAIRLY STRONG UPPER LEVEL DISTURBANCE WILL MOVE THROUGH SOUTHEAST WYOMING TODAY...BRINGING WIDESPREAD SNOW SHOWERS. SNOW SHOWERS COULD BECOME HEAVY AT TIMES LATER THIS MORNING AND PERSIST THROUGH THE AFTERNOON. AREAS ALONG AND EAST OF THE LARAMIE RANGE COULD SEE MODERATE TO HEAVY SNOW WITH SIGNIFICANT ACCUMULATIONS. A SNOW ADVISORY IS IN EFFECT FOR THE INTERSTATE 25 CORRIDOR FROM THE COLORADO STATE LINE TO DOUGLAS. SNOW WILL SLOWLY EASE TOWARDS LATE AFTERNOON. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY BREEZY TO WINDY CONDITIONS ARE EXPECTED OVER THE AREA SATURDAY AND SUNDAY WITH LOCAL GUSTS IN EXCESS OF 50 MPH POSSIBLE. A SLOW MOVING LOW PRESSURE SYSTEM IS EXPECTED TO AFFECT THE AREA MONDAY THROUGH WEDNESDAY BRINGING PERIODS OF SNOW. SIGNIFICANT ACCUMULATING SNOWS ARE POSSIBLE DUE TO THE SLOW MOVEMENT OF THIS SYSTEM. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT. WE WOULD APPRECIATE ANY REPORTS ON NEW SNOW ACCUMULATIONS THIS AFTERNOON THOUGH TO HELP US GAGE THE INTENSITY OF THIS SNOW EVENT. PLEASE PASS YOUR SNOW REPORTS TO THE NATIONAL WEATHER SERVICE IN CHEYENNE. && THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC...AND CLIMATE INFORMATION IS AVAILABLE ON THE WEB AT... HTTP://WEATHER.GOV/CHEYENNE
The national radar mosaic for the moment the first event began.
7 winter weather. Local standard time, as filed.
The Old Battle SNOTEL site (elevation 10000 ft) estimated six inches of snow.
The Whiskey Park SNOTEL site (elevation 8950 ft) estimated eleven inches of snow.
The Blackhall Mountain SNOTEL site (elevation 9820 ft) estimated nine inches of snow.
The South Brush Creek SNOTEL site (elevation 8440 ft) estimated eight inches of snow.
The North French Creek SNOTEL site (elevation 10130 ft) estimated eleven inches of snow.
The Sand Lake SNOTEL site (elevation 10050 ft) estimated seven inches of snow.
The Brooklyn Lake SNOTEL site (elevation 10240 ft) estimated seven inches of snow.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2013Every state in 2013This day in weather historyWarnings in Wyoming, April 2013
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 2026-10-01. Each event’s entry at NCEI: 436747, 436748, 436750, 436752, 436753, 436757, 436759.