A fast moving low pressure system increased the pressure gradient over southeast Wyoming. The result was a brief period of strong gap winds through the wind corridors.
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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 low pressure system increased the pressure gradient over southeast Wyoming. The result was a brief period of strong gap winds through the wind corridors.
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 Feb 18, 9:39 PM MST, 5 hours 16 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHEYENNE WY 939 PM MST WED FEB 18 2015 .UPDATE... ISSUED AT 932 PM MST WED FEB 18 2015 NO BIG CHANGES TO TONIGHTS FORECAST. MARGINAL SHORT LIVED HIGH WIND EVENT STILL EXPECTED TONIGHT. BASED ON THE LATEST MODEL RUNS THE STRONGEST WINDS WILL BE BETWEEN 3 AM MST AND 9 AM MST. NO CHANCES FOR PRECIPITATION TONIGHT ONLY SOME MID LEVEL CLOUDS OVER THE NEBRASKA PANHANDLE WHICH WILL CLEAR FROM WEST TO EAST AND EVENTUALLY LET TEMPERATURES FALL INTO THE TEENS LATE TONIGHT. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 429 PM MST WED FEB 18 2015 THE ARCTIC BOUNDARY CURRENTLY BISECTS THE FORECAST AREA NORTHWEST-SOUTHEAST THIS AFTERNOON...WITH TEMPS HOLDING IN THE LOW/MID 30S TO THE EAST OF THE BOUNDARY AND 30S/40S TO THE WEST. WINDS ARE ALSO QUITE BREEZY TO THE WEST AS THIS BOUNDARY REMAINS QUASI-STATIONARY...WITH GUSTS OF 40 TO 50 MPH QUITE COMMON ALONG AND WEST OF I-25. THIS TREND WILL CONTINUE THROUGH THIS EVENING AS THE BOUNDARY HOLDS POSITION. A RELATIVELY WEAK SHORTWAVE TROUGH WILL APPROACH FROM THE NORTHWEST TONIGHT AND WILL DEEPEN THE LEESIDE PRESSURE TROUGH THROUGH EARLY THURSDAY MORNING. THE LLVL GRADIENT IS PROGGED TO REMAIN ON THE MARGINAL SIDE AROUND 50 DAM...BUT MODELS STILL PEG WINDS JUST OFF THE SURFACE TO BE IN THE VICINITY OF 50 TO 60 KTS FROM 09-18Z. THINK THAT THE SHORTWAVE PASSAGE IN COMBINATION WITH A DEVELOPING MOUNTAIN WAVE WILL BE JUST ENOUGH TO FORCE THESE STRONG WINDS TO THE SFC IN THE WIND PRONE AREAS. SO WENT AHEAD AND ISSUED A HIGH WIND WARNING FOR THE TYPICAL ARLINGTON-VEDAUWOO- BUFORD-BORDEAUX AREAS WITH HIGHEST CONFIDENCE THAT WINDS WILL BE STRONGEST ALONG THE I-80 CORRIDOR. THINK HIGHEST GUSTS WILL REMAIN AROUND 60 MPH. THE GRADIENT WILL RELAX SOMEWHAT THRU THE REMAINDER OF THURSDAY AS THE BOUNDARY SHIFTS WELL EAST OF THE AREA WITH THE DEPARTING SHORTWAVE...ALTHOUGH WINDS WILL REMAIN BREEZY. TEMPS WILL BE QUITE MILD IN THE 40S AND 50S WITH DRY CONDITIONS. ATTENTION THEN TURNS TOWARD A MAJOR PATTERN STARTING FRIDAY AS A DEEP UPPER LEVEL TROUGH BEGINS TO DIG INTO THE WESTERN CONUS. THE LEADING EDGE SHORTWAVE TROUGH WILL SLIDE SOUTHEAST INTO THE GREAT BASIN ON FRIDAY WITH SURFACE CYCLOGENESIS OCCURRING OVER SOUTHEAST COLORADO FRIDAY AFTERNOON IN ADVANCE OF THIS WAVE. SFC WINDS OVER THE CWA WILL SHIFT TO THE NORTH IN RESPONSE TO THE DEVELOPING LOW AND WILL DRAW A COLD FRONT SOUTH ACROSS THE AREA IN THE LATE AFTERNOON. THE ASSOCIATED MOISTURE PLUME WILL OVERSPREAD THE REGION AS THE SHORTWAVE APPROACHES...SO EXPECTING PRECIP TO DEVELOP ACROSS THE CWA THROUGH THE DAY. MODELS HOLD OFF ON ADVECTING THE DEEPER MOISTURE UNTIL LATER FRIDAY AFTERNOON SO WILL BACK OFF POPS A BIT FOR FRIDAY MORNING AND EARLY AFTERNOON OVER THE PLAINS...BUT WILL MAINTAIN AS IS FOR THE MOUNTAINS. TEMPS WILL BE SUFFICIENTLY COLD ENOUGH OVER THE HIGH COUNTRY TO KEEP MOSTLY SNOW OR A RAIN/SNOW MIX...WHILE CHANCES ARE THAT MOST OF THE ACTIVITY OVER THE PLAINS WILL REMAIN RAIN. ONCE THE FRONT ROLLS THROUGH IN THE AFTERNOON THOUGH...EXPECT A RAPID CHANGEOVER TO SNOW AS FORECAST SOUNDINGS ILLUSTRATE A QUICK DROP IN TEMPERATURE. LIKELY TO SEE A FEW INCHES OF SNOW ACCUMULATION IN THE MOUNTAINS THROUGH THE DAY...WITH NOT MUCH EXPECTED IN THE LOWER ELEVATIONS UNTIL FRIDAY NIGHT. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 429 PM MST WED FEB 18 2015 MAIN FORECAST CHALLENGES EARLY IN THE PERIOD WILL DEAL WITH ACCUMULATING SNOWFALL AND WINDS. LATEST GFS/ECMWF MODEL SOLUTIONS ARE IN REASONABLE AGREEMENT WITH THE POSITION AND STRENGTH OF THE LONG WAVE TROUGH OVER MUCH OF THE LOWER 48 THIS WEEKEND INTO EARLY NEXT WEEK. LEAD SHORTWAVE WILL DIVE SOUTHEAST FROM THE GREAT BASIN ACROSS THE FOUR CORNERS REGION FRIDAY NIGHT AND SATURDAY. ARCTIC COLD FRONT WILL BE MOVING SOUTH INTO NORTHERN COLORADO FRIDAY NIGHT WITH UPSLOPE NORTHEASTERLY FLOW...MOISTURE AND OMEGA ENHANCING SNOWFALL OVER MUCH OF SOUTHEAST WY AND WESTERN NE. BETTER LIFT AND UPSLOPE WILL BE MAXIMIZED SOUTH OF THE WY-CO BORDER...HOWEVER ACCUMULATING SNOWFALL WILL LIKELY OCCUR ALONG THE INTERSTATE 80 CORRIDOR. GUSTY NORTHEAST WINDS WILL DEVELOP SATURDAY AS 700MB WINDS PEAK AROUND 30 KT. THE COMBINATION OF FALLING AND BLOWING SNOW WILL RESULT IN HAZARDOUS TRAVEL. STILL TOO EARLY TO PIN DOWN EXACT SNOW TOTALS WITH THIS SYSTEM...BUT LOOKING AT ADVISORY SNOWFALL AMOUNTS OUTSIDE THE MOUNTAINS WITH POTENTIAL 3-6". THE SNOWY/SIERRA MADRE AND SOUTHERN LARAMIE RANGES COULD MEASURE 8-12". WILL BE REFINING THESE AMOUNTS AND TIMING AS THE EVENT DRAWS CLOSER. MUCH COLDER TEMPERATURES ARE FORECAST FOR SATURDAY WITH HIGHS IN THE 20S TO LOWER 30S WITH WIND CHILLS IN THE SINGLE DIGITS AND TEENS. SNOW WILL CONTINUE SATURDAY NIGHT AND GRADUALLY TAPER OFF FROM NORTH TO SOUTH SUNDAY. 1045MB SURFACE HIGH MOVES ACROSS THE DAKOTAS INTO MN/IA SUNDAY NIGHT. SURFACE WINDS WILL VEER AROUND TO SOUTHERLY... BUT WILL HAVE LITTLE EFFECT ON HIGH TEMPERATURES. STRONG NORTHERLY FLOW ALOFT AND COLD AIR ADVECTION WILL KEEP SUNDAY/S HIGHS IN THE MID TEENS TO MID 20S. CLEARING SKIES AND LIGHTER WINDS ALONG WITH FRESH SNOWPACK WILL CAUSE LOW TEMPERATURES SUNDAY NIGHT TO BOTTOM OUT INTO THE SINGLE DIGITS...WITH A FEW SUB-ZERO READINGS FOR THE VALLEYS WEST OF THE LARAMIE RANGE. TEMPERATURES EARLY NEXT WEEK WILL SLOWLY MODERATE BUT AVERAGE BELOW SEASONAL NORMALS /HIGHS MOSTLY 30S AND LOWS MOSTLY TEENS/. ANOTHER COLD FRONT MOVES THROUGH THE PLAINS TUESDAY WITH GUSTY NORTHWEST WINDS BUT NO PRECIPITATION. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 932 PM MST WED FEB 18 2015 VFR ACROSS SOUTHEAST WYOMING AND NEBRASKA PANHANDLE TONIGHT AND THURSDAY WITH CLEAR TO PARTLY CLOUDY SKIES. LIGHT WINDS TONIGHT FOR MOST LOCATIONS EAST OF THE LARAMIE RANGE BUT BREEZY TO WINDY CONDITIONS WILL BE FOUND TO THE WEST. MAIN AVIATION CONCERN WILL BE THE FAVORED WINDY AREAS IN SOUTHEAST WYOMING WHERE WESTERLY WINDS WILL GUST BETWEEN 40 AND 50 KTS LATE TONIGHT THROUGH THURSDAY MORNING. THESE STRONG WINDS WILL AFFECT THE NORTHERN SNOWY RANGE FOOTHILLS...THE SOUTHERN LARAMIE RANGE AND FOOTHILLS...AND WILL ALSO IMPACT AREAS NEAR BORDEAUX. SNOW IS EXPECTED TO DEVELOP OVER MUCH OF THE FORECAST AREA LATE FRIDAY WITH WIDESPREAD IFR DEVELOPING FRIDAY NIGHT THROUGH SATURDAY FOR AREAS NEAR THE COLORADO BORDER. && .FIRE WEATHER... ISSUED AT 429 PM MST WED FEB 18 2015 BREEZY TO WINDY CONDITIONS WILL CONTINUE THROUGH THURSDAY ALTHOUGH HUMIDITIES REMAINING IN THE 20S-40S WILL KEEP FIRE WEATHER CONCERNS MINIMAL. THE NEXT CHANCE FOR ACCUMULATING SNOW LOOKS TO BEGIN FRIDAY AS ANOTHER COLD FRONT MOVES INTO THE AREA FROM THE NORTH. SIGNIFICANT SNOW ACCUMULATIONS ARE POSSIBLE FOR THE I-80 CORRIDOR FROM SIDNEY TO RAWLINS THROUGH SUNDAY. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...HIGH WIND WARNING UNTIL NOON MST THURSDAY FOR WYZ106-110-116-117. NE...NONE. && UPDATE...SML SHORT TERM...RJM LONG TERM...MJ AVIATION...SML FIRE WEATHER...RJM
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHEYENNE WY 300 PM MST WED FEB 18 2015 NEZ002-003-019>021-054-055-095-096-WYZ101>105-107>109-111>115-118- 119-192200- DAWES-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-KIMBALL-CHEYENNE- NORTH SIOUX-SOUTH SIOUX-CONVERSE COUNTY LOWER ELEVATIONS- NIOBRARA COUNTY-NORTH LARAMIE RANGE- FERRIS/SEMINOE/SHIRLEY MOUNTAINS-SHIRLEY BASIN-EAST PLATTE COUNTY- GOSHEN COUNTY-CENTRAL CARBON COUNTY-SOUTHWEST CARBON COUNTY- SIERRA MADRE RANGE-UPPER NORTH PLATTE RIVER BASIN-SNOWY RANGE- LARAMIE VALLEY-CENTRAL LARAMIE COUNTY-EAST LARAMIE COUNTY- 300 PM MST WED FEB 18 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF WESTERN NEBRASKA...EAST CENTRAL WYOMING...SOUTH CENTRAL WYOMING AND SOUTHEAST WYOMING. .DAY ONE...THIS AFTERNOON AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY SNOW IS EXPECTED TO RETURN TO THE AREA BY LATE FRIDAY AND PERSIST THROUGH SATURDAY NIGHT BEFORE ENDING SUNDAY. ACCUMULATING SNOWS LOOK LIKELY OVER MANY AREAS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED. WYZ106-110-116-117-192200- CENTRAL LARAMIE RANGE AND SOUTHWEST PLATTE COUNTY- NORTH SNOWY RANGE FOOTHILLS-SOUTH LARAMIE RANGE- SOUTH LARAMIE RANGE FOOTHILLS- 300 PM MST WED FEB 18 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST CENTRAL WYOMING...SOUTH CENTRAL WYOMING AND SOUTHEAST WYOMING. .DAY ONE...THIS AFTERNOON AND TONIGHT WEST TO NORTHWEST WINDS OF 35 TO 45 MPH WITH GUSTS AROUND 60 MPH ARE EXPECTED AFTER MIDNIGHT TONIGHT FOR THE INTERSTATE 80 CORRIDOR FROM CHEYENNE TO LARAMIE AND IN THE ARLINGTON AREA...AND THE INTERSTATE 25 CORRIDOR FROM WHEATLAND TO CHUGWATER. A HIGH WIND WARNING IS IN EFFECT FROM MIDNIGHT TONIGHT THROUGH NOON THURSDAY FOR THESE AREAS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY SNOW IS EXPECTED TO RETURN TO THE AREA BY LATE FRIDAY AND PERSIST THROUGH SATURDAY NIGHT BEFORE ENDING SUNDAY. ACCUMULATING SNOWS LOOK LIKELY OVER MANY AREAS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED.
The national radar mosaic for the moment the first event began.
7 high wind. Local standard time, as filed.
The WYDOT sensor at Strouss Hill measured peak wind gusts of 60 mph.
The WYDOT sensor at Cooper Cove measured sustained winds of 40 mph or higher, with a peak gust of 60 mph at 19/0305 MST.
The WYDOT sensor at Arlington measured peak wind gusts of 58 mph.
The WYDOT sensor at Halleck Ridge measured peak wind gusts of 58 mph.
The UPR sensor at Lynch measured sustained winds of 40 mph or higher.
The WYDOT sensor at Wildcat Trail measured peak wind gusts of 58 mph.
The UPR sensor at Emkay measured sustained winds of 40 mph or higher.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2015Every state in 2015This day in weather historyWarnings in Wyoming, February 2015
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: 559666, 559655, 559650, 559661, 559686, 559710, 559713.