A strong upper level disturbance, instability and low level upslope flow generated several convective bands of moderate to heavy snow across the Laramie Valley, southern Laramie Range and Snowy Range. Snowfall measured between four to ten inches, with estimates of as much as 14 inches over the Snowy Range.
Every event with a place to put it; 4 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 strong upper level disturbance, instability and low level upslope flow generated several convective bands of moderate to heavy snow across the Laramie Valley, southern Laramie Range and Snowy Range. Snowfall measured between four to ten inches, with estimates of as much as 14 inches over the Snowy Range. Interstate 80 between Cheyenne and Sinclair was closed in both directions due to moderate to heavy snow, strong winds and blowing snow.
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 Mar 11, 2:25 AM MST, 8 hours 35 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHEYENNE WY 325 AM MDT MON MAR 11 2013 .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT... SATELLITE PIX EARLY THIS MORNING SHOW AN UPSTREAM SHORTWAVE OVER MONTANA BEING DRIVEN SOUTHEAST BY A JET STREAK OF WHICH 00Z UPPER AIR ANALYSIS OBSERVED AT AROUND 120-140 KNOTS ACROSS SOUTHERN BRITISH COLUMBIA. THIS SHORTWAVE WILL ACCELERATE SOUTHEAST THROUGH THE REGION LATER TODAY AND TONIGHT PRODUCING A PERIOD OF SHOWER ACTIVITY. UPSTREAM RADARS AT BILLINGS AND RIVERTON ARE ALREADY RETURNING LIGHT ECHOES...THOUGH OBSERVATION SITES HAVE YET TO CONFIRM ANY PRECIPITATION HAS REACHED THE GROUND. THIS IS EXPECTED TO CHANGE ACROSS EAST CENTRAL WYOMING THIS MORNING AS LLVL FORCING ALONG THE ASSOCIATED COLD FRONT COMBINES WITH THE FAVORABLE NOSE OF THE AFOREMENTIONED JET STREAK. ALTHOUGH SHOWERY...PRECIPITATION WILL BECOME MORE WIDESPREAD THIS AFTERNOON AS H7/H5 LAPSE RATES STEEPEN TO NEAR 8C/KM AND LIFTED INDICES FALL TO ZERO. MODELS EVEN SHOW SOME SBCAPE VALUES OF AROUND 100 J/KG ACROSS THE EASTERN PLAINS BY THIS AFTERNOON. ALTHOUGH NOT CONFIDENT ENOUGH TO INCLUDE IN THE FORECAST AT THIS TIME...WOULD NOT BE SURPRISED TO SEE A FEW LIGHTNING STRIKES LATER TODAY. PRECIPITATION PHASE WILL BE TRICKY AS SFC TEMPERATURES WILL BE PLENTY WARM FOR RAIN INITIALLY. HOWEVER...EVAPORATIVE COOLING WITHIN THE COLUMN WILL BE SUFFICIENT TO MIX OR TURN TO SNOW... ESPECIALLY IN MORE INTENSE CONVECTION. MODELS ALSO POINT TO A BROAD AREA OF NEGATIVE EPV CO-LOCATED WITH AN AREA OF LLVL FRONTOGENESIS WHICH WILL FURTHER STRENGTHEN THE CONVECTIVE SHOWERS IN AREAS OF ENHANCED CSI. THIS AREA OF BEST LIFT WILL DRIFT INTO EXTREME SOUTHEAST WYOMING AND THE SOUTHERN NEBRASKA PANHANDLE BY AROUND MIDNIGHT. AS SUCH WILL SEE A GRADUAL DECREASE IN SHOWER COVERAGE FROM NORTH TO SOUTH LATER TONIGHT. SNOWFALL AMOUNTS OF AN INCH OR TWO WILL DEFINITELY BE A POSSIBILITY WITHIN THESE HEAVIER BANDS ESPECIALLY AS TEMPERATURES FALL THIS EVENING. COULD EVEN SEE LOCALLY HIGHER AMOUNTS IF ANY OF THESE BANDS BECOME STATIONARY. VISIBILITIES WILL DROP WITHIN THESE HEAVIER BANDS THIS AFTERNOON AND WITH TEMPERATURES THAT WILL FALL BELOW FREEZING AFTER SUNSET...MAY SEE SOME POOR TRAVELLING CONDITIONS FOR A TIME THIS EVENING. MOSTLY DRY CONDITIONS WILL RETURN FOR TUESDAY AND WEDNESDAY AS NORTHWEST FLOW ENSUES ACROSS THE REGION. WILL SEE PERIODIC BOUTS WITH CLOUD COVER...ESPECIALLY TUESDAY NIGHT AND AGAIN WEDNESDAY NIGHT. HOWEVER...WITH THE JET AND STORM TRACK KEPT AT BAY NORTH OF THE CWFA...DO NOT EXPECT SUFFICIENT LIFT TO WARRANT ANY PRECIPITATION CHANCES. TEMPERATURES WILL IMPROVE DRAMATICALLY AS WELL AS H7 TEMPERATURES CLIMB FROM -6C TODAY AND TUESDAY TO NEAR FREEZING BY WEDNESDAY. SO HIGH TEMPERATURES WILL BE IN THE 40S TODAY AND TUESDAY...WITH 50S AND 60S RETURNING FOR WEDNESDAY. .LONG TERM...THURSDAY THROUGH SUNDAY... UPPER RIDGE WILL BE OVER THE REGION THURSDAY THROUGH FRIDAY WHILE SLOWLY DEAMPLIFYING AS SHORTWAVE ENERGY RIDES ALONG THE NORTHERN PARTS OF THE RIDGE. QUITE MILD TEMPERATURES WILL BE OVER THE CWA THURSDAY AND FRIDAY WITH MAXS LIKELY REACHING THE 70S OVER THE PLAINS... ESPECIALLY PARTS OF THE NEBRASKA PANHANDLE. MODELS THEN BEGIN DIVERGING ON SOLUTIONS WITH RESPECT TO HANDLING OF SHORTWAVE ENERGY OFF THE NORTHEAST PACIFIC BEGINNING OVER THE WEEKEND WITH THE ECMWF BUILDING AN UPPER RIDGE OVER THE WESTERN CONUS SUNDAY WHILE THE GFS CARVES OUT A TROF. ECMWF ALSO DRIVES A COUPLE OF SHORTWAVES ACROSS THE CWA SATURDAY AND SUNDAY WHILE GFS IS FARTHER NORTH WITH THE FIRST ONE AND MUCH SLOWER WITH THE SECOND. WILL GO WITH SOME LOW POPS MAINLY OVER WESTERN AND NORTHERN PARTS OF THE CWA WHERE AGREEMENT IS SOMEWHAT BETTER THOUGH STILL NOT ALL THAT GOOD AS WELL AS COOL THINGS DOWN SOME AS HEIGHTS LOWER. && .AVIATION...12Z TAF ISSUANCE... VFR EXPECTED OVER ALL TERMINALS MOST OF TODAY WITH VARYING AMOUNTS OF MAINLY MID LEVEL CLOUDS. GUSTY WEST TO NORTHWEST WINDS ESPECIALLY NEAR THE MTNS THROUGH THIS AFTERNOON. SFC COLD FRONT WILL PUSH SOUTH ACROSS THE PLAINS THIS EVENING LOWERING CIGS BEHIND IT...WITH WIDESPREAD MVFR/IFR CIGS TONIGHT ESPECIALLY FROM KRWL TO KCYS ALONG WITH DEVELOPING AREAS OF LIGHT SNOW. && .FIRE WEATHER... RELATIVELY COOL AND SHOWERY CONDITIONS TODAY WILL KEEP ANY FIRE WEATHER CONCERNS DOWN. CONDITIONS WILL BEGIN TO DRY OUT FOR TUESDAY...ALTHOUGH TEMPERATURES WILL CONTINUE TO BE COOL ACROSS THE DISTRICT. HIGH TEMPERATURES WILL ONLY REACH THE 40S EACH DAY...WHICH WILL RESULT IN MINIMUM RELATIVE HUMIDITIES DROPPING INTO 30 TO 40 PERCENT RANGE. TEMPERATURES WILL TURN WARMER FOR WEDNESDAY THROUGH FRIDAY WITH DRY CONDITIONS CONTINUING. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && SHORT TERM/FIRE WEATHER...HAHN LONG TERM/AVIATION...RE
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHEYENNE WY 1135 AM MDT MON MAR 11 2013 NEZ020-054-WYZ101>119-121100- BANNER-KIMBALL-CONVERSE COUNTY LOWER ELEVATIONS-NIOBRARA COUNTY- 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- 1135 AM MDT MON MAR 11 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA PANHANDLE...EAST CENTRAL WYOMING...SOUTH CENTRAL WYOMING AND SOUTHEAST WYOMING. .DAY ONE...THIS AFTERNOON AND TONIGHT A HIGH WIND WARNING IS IN EFFECT UNTIL 4 PM MDT THIS AFTERNOON FOR THE SOUTHERN LARAMIE RANGE...THE SOUTHERN LARAMIE RANGE FOOTHILLS AND CENTRAL LARAMIE COUNTY INCLUDING CHEYENNE. THE HIGH WIND WARNING ALSO INCLUDES THE SUMMIT OF INTERSTATE 80...INCLUDING BUFORD AND VEDAUWOO...AS WELL AS INTERSTATE 25 OVER LARAMIE COUNTY. EXPECT NORTHWEST WINDS 30 TO 40 MPH WITH GUSTS TO 60 MPH. SCATTERED TO NUMEROUS RAIN AND SNOW SHOWERS WILL OCCUR THIS AFTERNOON...MOST NUMEROUS OVER THE NORTHERN LARAMIE RANGE...THE SIERRA MADRE RANGE AND SNOWY RANGE...AND ALSO WEST OF INTERSTATE 25. SNOWFALL ACCUMULATIONS OF 2 TO 5 INCHES WILL OCCUR OVER THE MOUNTAINS SCATTERED SNOW SHOWERS WILL OCCUR THIS EVENING...MOST NUMEROUS EAST OF INTERSTATE 25 AND OVER THE SNOWY AND SIERRA MADRE RANGES. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .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 NEZ002-003-019-021-055-095-096-121100- DAWES-BOX BUTTE-SCOTTS BLUFF-MORRILL-CHEYENNE-NORTH SIOUX- SOUTH SIOUX- 1135 AM MDT MON MAR 11 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA PANHANDLE. .DAY ONE...THIS AFTERNOON AND TONIGHT ISOLATED TO SCATTERED RAIN AND SNOW SHOWERS WILL OCCUR THIS AFTERNOON...MOST NUMEROUS FROM NORTHERN SIOUX COUNTY TO NEAR SCOTTSBLUFF ALONG THE WYOMING STATE LINE. SCATTERED SNOW SHOWERS WILL OCCUR THIS EVENING THEN END AFTER MIDNIGHT. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .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 RUBIN
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE CHEYENNE WY 609 AM MDT MON MAR 11 2013 WYZ110-116-117-111500- NORTH SNOWY RANGE FOOTHILLS-SOUTH LARAMIE RANGE- SOUTH LARAMIE RANGE FOOTHILLS- INCLUDING THE CITIES OF...ARLINGTON...ELK MOUNTAIN...VEDAUWOO... BUFORD...PUMPKIN VINE...HORSE CREEK...HARRIMAN...WHITAKER 609 AM MDT MON MAR 11 2013 ...GUSTY WINDS ALONG PORTIONS OF INTERSTATE 80 THIS MORNING.. WEST WINDS OF 30 TO 35 WITH GUSTS OF 45 TO 55 MPH WILL OCCUR ALONG THE INTERSTATE 80 CORRIDOR THIS MORNING. MOTORISTS TRAVELING IN LIGHTWEIGHT OR HIGH PROFILE VEHICLES SHOULD BE PREPARED TO ENCOUNTER THESE STRONG AND GUSTY WINDS ALONG INTERSTATE 80 AROUND ARLINGTON AND BETWEEN CHEYENNE AND LARAMIE. WINDS WILL REMAIN BREEZY THROUGH THE AFTERNOON AND DECREASE SOME BY TONIGHT. THE WYOMING DEPARTMENT OF TRANSPORTATION ADVISES NO LIGHT TRAILER TRAFFIC DUE TO WIND SPEEDS ABOVE 50 MPH. THESE WINDS MAY CAUSE LOSS OF VEHICLE CONTROL OR A BLOW OVER TO HIGH PROFILE VEHICLES TRAVELING EMPTY OR WITH A LIGHT LOAD. DRIVERS OF SUCH VEHICLES ARE ADVISED TO DELAY TRAVEL. HAHN
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE CHEYENNE WY 1037 AM MDT MON MAR 11 2013 WYZ116>118-111800- SOUTH LARAMIE RANGE-SOUTH LARAMIE RANGE FOOTHILLS- CENTRAL LARAMIE COUNTY- INCLUDING THE CITIES OF...VEDAUWOO...BUFORD...PUMPKIN VINE... HORSE CREEK...HARRIMAN...WHITAKER...CHEYENNE 1037 AM MDT MON MAR 11 2013 ...STRONG WINDS NEAR THE SUMMIT OF INTERSTATE 80 THIS MORNING... WATCH FOR NORTHWEST WINDS OF 30 TO 45 MPH WITH VERY LOCALIZED GUSTS UP TO 60 MPH THIS MORNING OVER THE SUMMIT OF INTERSTATE 80 BETWEEN CHEYENNE AND LARAMIE...AS WELL AS OVER THE EASTERN FOOTHILLS OF WESTERN LARAMIE COUNTY TO THE WEST OF CHEYENNE ALONG INTERSTATE 80. IF YOU ARE DRIVING OVER THE SUMMIT OF INTERSTATE 80...OR OVER THE EASTERN FOOTHILLS OF THE LARAMIE RANGE OVER WESTERN LARAMIE COUNTY WEST OF CHEYENNE...WATCH FOR THE STRONG NORTHWEST WINDS AND SUDDEN GUSTS. THE WYOMING DEPARTMENT OF TRANSPORTATION ADVISES NO LIGHT TRAILER TRAFFIC DUE TO WIND SPEEDS ABOVE 50 MPH. THESE WINDS MAY CAUSE LOSS OF VEHICLE CONTROL OR A BLOW OVER TO HIGH PROFILE VEHICLES TRAVELING EMPTY OR WITH A LIGHT LOAD. DRIVERS OF SUCH VEHICLES ARE ADVISED TO DELAY TRAVEL. RUBIN
The national radar mosaic for the moment the first event began.
4 winter storm. Local standard time, as filed.
The Medicine Bow SNOTEL site (elevation 10500 ft) estimated a foot of snow.
The Brooklyn Lake SNOTEL site (elevation 10240 ft) estimated a foot of snow.
The Snowy Range ski resort measured 14 inches of snow.
There were several reports of six to nine inches of snow in and surrounding Laramie.
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, March 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 2026-09-24. Each event’s entry at NCEI: 432495, 432496, 432497, 432498.