A low pressure system brought light to moderate snow to the Snowy and Sierra Madre ranges. Snowfall estimates of four to ten inches were reported.
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The episode as NWS CYS wrote it up.
A low pressure system brought light to moderate snow to the Snowy and Sierra Madre ranges. Snowfall estimates of four to ten inches were reported.
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 20, 9:43 PM MST, 7 hours 17 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHEYENNE WY 1043 PM MDT WED MAR 20 2013 .AVIATION...06Z TAFS EXPECTING DETERIORATING CONDITIONS WEST OF THE LARAMIE RANGE THROUGH THE MORNING HOURS. THIS IN RESPONSE TO A COLD FRONT APPROACHING FROM THE WEST. THERE WERE SOME THUNDERSTORMS WITH THE FRONT OVER IDAHO AND WESTERN MONTANA YESTERDAY...SO EXPECTING PRECIP TO BE CONVECTIVE ONCE IT STARTS. PRECIP SPREADS INTO THE RAWLINS AREA TOWARDS THE 10-12Z TIME FRAME...SPREADING EAST TO LARAMIE BY LATE MORNING. COULD SEE SOME THUNDERSTORMS THURSDAY AFTERNOON...BUT STILL TOO FAR OUR TO ADD INTO TAFS. CLAYCOMB && PREV DISCUSSION... /ISSUED 332 PM MDT WED MAR 20 2013/ SHORT TERM...TONIGHT THROUGH FRIDAY... AREA OF SNOW SHOWERS SPREAD INTO THE FAR WEST PART OF THE CWA EARLY THIS AFTERNOON. AS OF 20Z...ASSOCIATED CLOUD TOPS HAVE BEEN WARMING AS THE SHOWERS MOVE EAST. THE KCYS RADAR STILL HAS SOME SHOWERS... MAINLY FROM NEAR KRWL TO KTOR. THE ACTIVITY WILL CONTINUE TO SPREAD EAST THROUGH THE EVENING IN ADVANCE OF A SHORTWAVE TROUGH. THAT FEATURE WILL BE EAST OF THE CWA EARLY THURSDAY MORNING. THE PRECIPITATION WILL TAPER OFF AN END OVER THE EAST PART OF THE CWA FROM LATE EVENING THROUGH EARLY THURSDAY MORNING. SOME SHOWERS WILL LINGER OVER MAINLY CARBON COUNTY THE REST OF THE NIGHT. PRECIPITATION TYPE WILL BE A MIX OF RAIN AND SNOW THROUGH THE EVENING DUE TO STILL MILD SURFACE AND 700 MB TEMPERATURES. HOWEVER...THE DRY LOW LEVELS SHOULD ALLOW FOR THE PRECIPITATION TO WET BULB OUT AND BECOME MORE SNOW THROUGH THAT TIME. AS THE PRECIPITATION HEADS EAST...FORECAST PROFILES SUGGEST THE POSSIBILITY OF FREEZING RAIN FROM LATE THIS EVENING THROUGH EARLY THURSDAY MORNING OVER PARTS OF THE PANHANDLE. THE OTHER CONCERN FOR TONIGHT WILL BE THE WINDS. SOUTHWEST SURFACE WINDS WERE GUSTING AS HIGH AS 48 MPH CURRENTLY NEAR KARL. THE LOW LEVEL HEIGHT DIFFERENCES AND SUBSIDENCE SHOULD INCREASE BY LATE EVENING WITH THE PASSAGE OF THE SHORTWAVE TROUGH. WILL GO AHEAD AND UPGRADE THE HIGH WIND WATCH TO A HIGH WIND WARNING FOR THE KARL AREA FROM 03Z TO 15Z THURSDAY AS THAT AREA LOOKS MOST LIKELY TO REACH HIGH WIND CRITERIA. THE REST OF THE FORECAST WILL REMAIN UNSETTLED. A SHORTWAVE TROUGH CURRENTLY ENTERING THE PACIFIC NORTHWEST MOVES ACROSS THE CENTRAL AND NORTHERN ROCKIES THURSDAY. STRONG COLD AIR ADVECTION WITH THE FEATURE...JET DYNAMICS AND SURFACE FORCING SHOULD ALLOW FOR ANOTHER ROUND OF SHOWERS BY THE AFTERNOON HOURS. THE ATMOSPHERE BECOMES UNSTABLE AND SO RAIN AND SNOW SHOWERS...SLEET AND ICE PELLETS WILL BE POSSIBLE. TEMPERATURES WILL STILL BE ABOVE FREEZING OVER THE LOWER ELEVATIONS ON THURSDAY ADDING TO THE PRECIPITATION TYPE CONCERNS. GUSTY NORTH TO NORTHWEST WINDS TO 45 MPH CAN ALSO BE EXPECTED. MOST LOCATIONS WILL RECEIVE ONLY A DUSTING OF SNOW...WITH THE MOUNTAINS RECEIVING 2 TO 4 INCHES OF NEW SNOW. CONDITIONS FOR AT LEAST BRIEF PERIODS WILL BE POOR IN THE AFTERNOON HOURS WITH THE WINDS AND VISIBILITY RESTRICTIONS. BY FRIDAY...ANOTHER SHORTWAVE TROUGH ROTATES AROUND THE NEWLY FORMED NORTHERN HIGH PLAINS CLOSED LOW. THAT WILL CREATE MORE SHOWERS AND GUSTY WINDS. TEMPERATURES WILL BE COOLER ON FRIDAY AND WILL ALLOW FOR SMALL ACCUMULATIONS OF SNOW OVER THE LOWER ELEVATIONS AND ANOTHER FEW INCHES OVER THE MOUNTAINS. EACH SHORTWAVE TROUGH WILL DEVELOP A SURFACE LOW OVER EASTERN COLORADO. IN GENERAL...INCREASED POPS AND MOUNTAIN SNOW AMOUNTS AND WINDS AND LOWERED TEMPERATURES. LONG TERM...FRIDAY NIGHT THROUGH NEXT WEDNESDAY...COLD AND SNOWY WEATHER PATTERN APPEARS MORE LIKELY THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK AS A STORM SYSTEM AND SEVERAL DISTURBANCES IMPACTING THE REGION. ACROSS PORTIONS OF SOUTHEAST WYOMING...MAY SEE SNOWFALL EVERY DAY THROUGH MONDAY AFTERNOON AS THE LAST DISTURBANCE ALOFT PUSHES ACROSS THE AREA. THE MAIN FORECAST CONCERN IS THE NEARLY STATIONARY UPPER LEVEL POLAR LOW ACROSS THE NORTHERN ROCKIES AND NORTHERN PLAINS INTO NEXT WEEK. MODELS SHOW A VIGOROUS SHORTWAVE PUSHING SOUTHEAST ON THE WESTERN SIDE OF THIS POLAR LOW THROUGH FRIDAY NIGHT. WITH AMPLE JET ENERGY ALOFT AND THE TROUGH DIGGING SOUTHWARD INTO THE CENTRAL ROCKIES...AND THEN EJECTING EASTWARD...THERE IS THE POTENTIAL FOR WINTER STORM ACROSS THE MOUNTAINS OF SOUTHEAST WYOMING AND HIGH PLAINS EAST OF THE LARAMIE RANGE. MOST MODELS ARE IN GOOD AGREEMENT...INCLUDING THE GEM AND ECMWF WHICH ARE THE MOST AGGRESSIVE WITH PRECIP AMOUNTS...UPWARDS OF 0.50 TO 0.75 INCHES OF LIQUID. THE NAM STILL SHOWS WIDESPREAD SNOW BUT NOT AS INTENSE AND MOSTLY DUE TO A FRONTAL BOUNDARY STALLING ACROSS THE AREA ALONG WITH UPSLOPE FLOW. THE GFS IS THE LEAST AGGRESSIVE AND MOST PROGRESSIVE SOLUTION...SHOWING THE SHORTWAVE REMAINING AS AN OPEN WAVE AS IT QUICKLY MOVES EASTWARD INTO THE PLAINS BY SATURDAY. HOWEVER...THE GFS ENSEMBLES ARE IN POOR AGREEMENT AND SHOW SEVERAL SOLUTIONS COMPARABLE TO THE ECMWF AND GEM. INCREASED POP BETWEEN 50 TO 80 PERCENT AS SNOW FALL LOOKS LIKELY LATE FRIDAY AND SATURDAY. TOO EARLY TO COMMIT TO SNOW ACCUMULATIONS...ALTHOUGH MODERATE SNOW ACCUMULATIONS LOOK GOOD AT THIS TIME. HIGH TEMPERATURES IN THE 20S TO LOW 30S WILL BE COMMON ALL WEEKEND WITH LOWS LIKELY IN THE SINGLE DIGITS AND TEENS BY SUNDAY MORNING. THE UPPER LEVEL LOW NEAR THE CANADIAN BORDER WILL REMAIN STATIONARY INTO EARLY NEXT WEEK. JET AND SHORTWAVE ENERGY WILL CONTINUE TO ROTATE AROUND THIS MAIN LOW WHICH WILL RESULT IN PERIODS OF SNOW SHOWERS ON SUNDAY...AND THEN AGAIN ON MONDAY. WITH DECENT LLVL INSTABILITY...BRIEF BUT HEAVY SNOW IS POSSIBLE EACH DAY WITHIN THE HEAVIEST SHOWERS WHICH MAY RESULT IN A QUICK INCH OR TWO OF ADDITIONAL SNOW ACCUMULATION. IT WILL REMAIN COLD INTO TUESDAY WITH HIGH TEMPERATURES BARELY CLIMBING INTO 30S. MODELS SHOW THE POLAR UPPER LOW FINALLY PROGRESSING EASTWARD ON WEDNESDAY AS HIGH TEMPERATURES INCREASE INTO THE UPPER 30S TO MID 40S ACROSS THE AREA. FIRE WEATHER...COOLER WEATHER WILL AFFECT THE CWA THROUGH EARLY NEXT WEEK. A SERIES OF STORM SYSTEMS WILL ALSO PRODUCE SHOWERS OVER THE REGION THROUGH FRIDAY...WITH ACCUMULATING SNOW OVER THE MOUNTAINS. MORE WIDESPREAD AND ACCUMULATING SNOW WILL AFFECT THE CWA FRIDAY NIGHT AND SATURDAY. GUSTY WINDS WILL OCCUR IN AREAS ALONG AND WEST OF THE LARAMIE RANGE TONIGHT AND THEN OVER THE ENTIRE CWA THURSDAY THROUGH SATURDAY. WARMER AND DRIER WEATHER WILL RETURN TO THE REGION BY NEXT WEDNESDAY. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...HIGH WIND WARNING UNTIL 9 AM THURSDAY FOR WYZ110. NE...NONE. && SHORT TERM/FIRE WEATHER...WEILAND LONG TERM/AVIATION...TJT
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHEYENNE WY 328 PM MDT WED MAR 20 2013 WYZ101>119-211230- 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- 328 PM MDT WED MAR 20 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST CENTRAL WYOMING... SOUTH CENTRAL WYOMING AND SOUTHEAST WYOMING. .DAY ONE...THIS AFTERNOON AND TONIGHT WEST TO SOUTHWEST WINDS WILL GUST AS HIGH AS 45 MPH IN AREAS ALONG AND WEST OF THE LARAMIE RANGE THROUGH TONIGHT. THE WINDS WILL BE STRONGER WITH GUSTS TO 60 MPH POSSIBLE AFTER 9 PM IN THE ARLINGTON AREA. A HIGH WIND WARNING HAS BEEN ISSUED FOR THAT AREA STARTING AT 9 PM. AREAS OF RAIN AND SNOW SHOWERS WILL OCCUR OVER THROUGH THIS EVENING. THE SHOWERS WILL BE ALL SNOW OVER AND NEAR THE MOUNTAINS THROUGH TONIGHT. TWO TO FOUR INCHES OF NEW SNOW ARE EXPECTED BY SUNRISE OVER THE SNOWY AND SIERRA MADRE RANGES. UP TO ONE HALF INCH OF NEW SNOW IS EXPECTED OVER THE NEARBY LOWER ELEVATIONS. THE SNOW AND WINDS WILL CREATE AREAS OF BLOWING AND DRIFTING SNOW AND REDUCED VISIBILITIES OVER THOSE MOUNTAINS TONIGHT. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY SNOW SHOWERS WILL CONTINUE IN THE MOUNTAINS AND NEARBY VALLEYS ON THURSDAY AND AGAIN ON FRIDAY. RAIN AND SNOW SHOWERS WILL OCCUR OVER THE LOWER ELEVATIONS MIXED AT TIMES WITH SLEET. THE MOUNTAINS WILL RECEIVE AN ADDITIONAL 2 TO 4 INCHES OF SNOW ON THURSDAY. A STORM SYSTEM WILL BRING WIDESPREAD ACCUMULATING SNOW TO SOUTHEAST WYOMING FRIDAY NIGHT AND SATURDAY. WEST TO NORTHWEST WINDS WILL GUST AS HIGH AS 45 MPH OVER SOUTHEAST WYOMING ON THURSDAY. STRONGER WINDS...WITH GUSTS TO 60 MPH WILL STILL BE POSSIBLE IN THE ARLINGTON AREA THROUGH 9 AM THRUSDAY. A HIGH WIND WARNING IS IN EFFECT FOR THAT AREA THROUGH 9 AM THURSDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED THIS AFTERNOON 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>021-054-055-095-096-211230- DAWES-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-KIMBALL-CHEYENNE- NORTH SIOUX-SOUTH SIOUX- 328 PM MDT WED MAR 20 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA PANHANDLE. .DAY ONE...THIS AFTERNOON AND TONIGHT SNOW SHOWERS ARE POSSIBLE FROM LATE THIS EVENING THROUGH EARLY THURSDAY MORNING OVER THE PANHANDLE. ANY ACCUMULATIONS WILL BE LESS THAN ONE HALF INCH. IN ADDITION...AREAS OF FREEZING RAIN WILL BE POSSIBLE LATE THIS EVENING THROUGH EARLY THURSDAY MORNING. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY RAIN AND SNOW SHOWERS WILL OCCUR OVER THE PANHANDLE MIXED AT TIMES WITH SLEET. A STORM SYSTEM WILL BRING WIDESPREAD ACCUMULATING SNOW TO THE WESTERN NEBRASKA PANHANDLE FRIDAY NIGHT AND SATURDAY. NORTHWEST WINDS WILL GUST AS HIGH AS 40 MPH OVER THE PANHANDLE ON THURSDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED THIS AFTERNOON AND TONIGHT. && THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC...AND CLIMATE INFORMATION IS AVAILABLE ON THE WEB AT... HTTP://WEATHER.GOV/CHEYENNE WEILAND
The national radar mosaic for the moment the first event began.
6 winter weather. Local standard time, as filed.
The Sage Creek Basin SNOTEL site (elevation 7850 ft) estimated six inches of snow.
The Divide Peak SNOTEL site (elevation 8880 ft) estimated eight inches of snow.
The Sandstone Ranger Station SNOTEL site (elevation 8150 ft) estimated six inches of snow.
The Whiskey Park SNOTEL site (elevation 8950 ft) estimated ten inches of snow.
The Blackhall Mountain SNOTEL site (elevation 9820 ft) estimated six inches of snow.
The North French Creek SNOTEL site (elevation 10130 ft) estimated eight 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, 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: 432554, 432555, 432556, 432557, 432558, 432559.