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000
FXUS65 KCYS 252209
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
309 PM MST WED FEB 25 2015

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 309 PM MST WED FEB 25 2015

SFC COLD FRONT HAS SLID SOUTH OF THE CWFA TODAY LEAVING NORTHERLY
LLVL WINDS IN ITS WAKE. MODERATE TO AT TIMES HEAVY BANDS OF SNOW
DEVELOPED INITIALLY OVR THE HIER TERRAIN AS WELL AS ACROSS
NORTHEASTERN LARAMIE COUNTY. THIS POCKET OF MODERATE SNOW EXPANDED
AS IT SHIFTED WEST THRU MUCH OF THE DAY WITH THE MOST INTENSE AXIS
AT 21Z SETTLING ON THE SRN LARAMIE RANGE. LATEST SATELLITE PIX
SHOW CONVECTIVE ELEMENTS ESPECIALLY OVR THE HIER TERRAIN OF SRN
CARBON COUNTY WHERE INSTABILITY WAS PROGD TO BE THE GREATEST.
AREAS OF BLOWING SNOW IS ALSO A CONCERN WITH RECENT WIND GUSTS
OBSERVED AT 25- 35 MPH ACROSS SE WYOMING. IN AN EARLIER UPDATE
EXPANDED THE WINTER WEATHER ADVISORY INTO ARLINGTON AS WELL AS OVR
THE SRN LARAMIE RANGE FOOTHILLS LARAMIE COUNTY...WHERE SNOWFALL
RATES FROM BOTH WEBCAMS AND KCYS RADAR RETURNS WERE THE GREATEST.
THESE SNOWFALL RATES WILL WANE SOMEWHAT WITH INSTABILITY LOSS THIS
EVENING...THOUGH LINGERING LIGHT SNOW WILL STILL BE A GOOD
POSSIBILITY. IF SNOWFALL RATES ALLOW...EVENING SHIFT MAY BE ABLE
TO CANX THE ADVISORY EARLY. A COLD NIGHT AHEAD...ESPECIALLY ACROSS
SOUTHEAST WYOMING WHERE THE COMBINATION OF FRESH SNOWPACK AND SOME
LLVL CAA PLUMMET LOW TEMPERATURES TO AROUND 0F IN THE LARAMIE
VALLEY AND SINGLE DIGITS ELSEWHERE.

ALTHOUGH BEST SHORTWAVE ENERGY SHIFTS SOUTH OVERNIGHT...LLVL
FRONT WILL BECOME STATIONARY ACROSS CARBON COUNTY AT LEAST THRU
THE DAY ON THURSDAY. MODELS SUGGEST A SECONDARY SHORTWAVE WILL
PUSH ATOP THE FRONT PRODUCING SOME PERIODS OF LIGHT SNOW OR
FLURRIES. HIER ELEVATIONS AND AREAS NR THE CO/WY STATELINE WILL
HAVE THE BEST OPPORTUNITY TO SEE LT SNOW ON THURSDAY. ANY
ACCUMULATIONS WILL BE VERY LIGHT WITH PERHAPS UP TO AN INCH
POSSIBLE. THURSDAY WILL BE COLDER HOWEVER WITH HIGHS THAT WILL
RISE GENERALLY JUST INTO THE TEENS.

THE PATTERN BEGINS TO FLATTEN ON FRIDAY AS THE NEXT UPSTREAM
TROUGH CARVES TOWARDS THE GREAT BASIN. LLVL FLOW TURNS SOUTHEAST
AHEAD OF IT WHICH IS TYPICALLY A FAVORABLE FOG PATTERN FOR THE
CHEYENNE RIDGE AND LARAMIE COUNTY. SO IT WILL LIKELY BE A
CLOUDY/FOGGY START TO THE DAY FOR FRIDAY. FLATTENING FLOW WILL
PUSH THE FRONT EAST TO AROUND THE LARAMIE RANGE BY LATE FRIDAY.
THIS WILL HELP TEMPERATURES UP A FEW DEGREES WITH TEENS AND 20S
EXPECTED MOST AREAS. OUTSIDE OF MOUNTAIN LOCATIONS...SNOW CHANCES
WILL BE MINIMAL ON FRIDAY.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 309 PM MST WED FEB 25 2015

SATURDAY...ARCTIC AIR REMAINS ENTRENCHED THUS STILL WELL BELOW
NORMAL TEMPERATURES. SUFFICIENTLY MOIST AIRMASS PROGGED AND WITH
SOUTHWEST FLOW ALOFT AND AN APPROACHING SHORTWAVE TROUGH ALOFT AND
OROGRAPHICS...WILL SEE WIDESPREAD SNOWS OVER THE SNOWY AND SIERRA
MADRE RANGES WITH SCATTERED SNOW SHOWERS NEARBY.

SUNDAY...MOIST SOUTHWEST FLOW ALOFT CONTINUES PRODUCING WIDESPREAD
OROGRAPHIC SNOWS OVER OUR NORTHERN LARAMIE...SNOWY AND SIERRA MADRE
RANGES WITH MOSTLY DRY CONDITIONS ELSEWHERE. CONTINUED COLD WITH
ARCTIC AIR ENTRENCHED.

MONDAY...ARCTIC AIR WILL RETREAT EASTWARD WITH TEMPERATURES WARMING.
GFS LOOKS OVERDONE WITH QPF WITH THE SHORTWAVE TROUGH ALOFT MOVING
ACROSS AND PREFER THE LESS AMPLIFIED AND DRIER ECMWF VERSION WHICH
MESHES WELL WITH OUR SURROUNDING NEIGHBORING OFFICES...THUS EXPECT
SCATTERED OROGRAPHIC SNOWS OVER THE SNOWY AND SIERRA MADRE RANGES
AND DRY ELSEWHERE.

TUESDAY...COLD TEMPERATURES CONTINUE IN THE WAKE OF ANOTHER PASSING
ARCTIC COLD FRONT. MOIST WEST FLOW ALOFT AND ADEQUATE LOW AND MID
LEVEL MOISTURE WILL KEEP SCATTERED SNOWS WEST OF INTERSTATE 25 AND
MOSTLY DRY ELSEWHERE DUE TO DOWNSLOPING MID LEVEL WINDS.

WEDNESDAY...FLOW ALOFT TURNS NORTHWEST. NOW THE ECMWF LOOKS OVERDONE
WITH RESPECT TO QPF AND PREFER THE DRIER GFS VERSION SHOWING DRY AND
COLD NORTHWEST FLOW ALOFT...THUS EXPECT A WINDY DAY WITH PERHAPS A
FEW MOUNTAIN SNOW SHOWERS...AND DRY ELSEWHERE...WHICH MESHES WELL
WITH OUR SURROUNDING NEIGHBORING OFFICES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1125 AM MST WED FEB 25 2015

ARCTIC COLD FRONT SWEPT THROUGH WITH COLD AIR PLUNGING SOUTH.
VFR AND MVFR PREVAILS THIS AFTERNOON...WITH AREAS OF IFR AND
MOUNTAIN OBSCUREMENT IN SNOW SHOWERS AND FOG AND BLOWING SNOW...
THEN MVFR PREVAILS TONIGHT WITH AREAS OF IFR IN SNOW...FOG AND
LOW CLOUDS...WITH IMPROVING CEILINGS AND VISIBILITIES AFTER
DAYBREAK ON THURSDAY...WITH LOCALIZED IFR IN SNOW SHOWERS AND
FOG.

&&

.FIRE WEATHER...
ISSUED AT 309 PM MST WED FEB 25 2015

COLD TEMPERATURES AND UNSETTLED CONDITIONS WILL HOLD ANY FIRE
WEATHER CONCERNS AT BAY FOR THE FORESEEABLE FUTURE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER WEATHER ADVISORY UNTIL 2 AM MST THURSDAY FOR WYZ110-
     114>117.

NE...NONE.

&&

$$

SHORT TERM...CAH
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...CAH