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000
FXUS65 KCYS 061727
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1027 AM MST FRI DEC 6 2013

.SHORT TERM...(TODAY AND THROUGH SATURDAY NIGHT)
ISSUED AT 303 AM MST FRI DEC 6 2013

CONTINUED VERY COLD CONDITIONS CAN BE EXPECTED THROUGH SATURDAY
NIGHT. IN ADDITION...SKIES WILL BE MOSTLY CLOUDY WITH INCREASING
CHANCES FOR SNOW.

TEMPERATURES EARLY THIS MORNING ACROSS THE CWA WERE BELOW ZERO WITH
BITTER COLD WIND CHILLS IN SOME AREAS. THE LARAMIE VALLEY WAS THE
COLDEST AREA...WITH WIND CHILL VALUES AT KLAR AT 09Z OF 45 BELOW
ZERO. CLOUD COVER IN SOME AREAS HAS KEPT TEMPERATURES A BIT WARMER
THAN THOSE OF LAST NIGHT. WILL CONTINUE THE WIND CHILL WARNINGS AND
ADVISORIES GOING THROUGH 15Z.

THE FLOW ALOFT SLOWLY BACKS THROUGH SATURDAY IN ADVANCE OF A
DEVELOPING SHORTWAVE TROUGH. BY 00Z SUNDAY...MODELS HAVE THE TROUGH
AXIS FROM WESTERN MONTANA TO NEVADA. AHEAD OF THE FEATURE WILL BE
SEVERAL WEAKER SHORTWAVE TROUGHS AND AN INCREASINGLY DIFFLUENT FLOW
ALOFT. THE INITIAL SHORTWAVE TROUGH WAS OVER WESTERN WYOMING EARLY
THIS MORNING AND WILL MOVE EAST OF THE CWA BY 00Z. MOSTLY CLOUDY
SKIES AND AREAS OF LIGHT SNOW OR FLURRIES CAN BE EXPECTED TODAY.
THE ACTIVITY WILL SHIFT TO MORE OF THE WEST AND NORTH PARTS OF THE
CWA TONIGHT AND SATURDAY MORNING AS THE FLOW ALOFT BACKS. BY
SATURDAY AFTERNOON...THE MORE FAVORABLE DYNAMICS WILL BE OVER THE
ENTIRE CWA WITH THE LIGHT SNOW INCREASING IN COVERAGE. THE TROUGH
AXIS MOVES OVER WESTERN WYOMING SATURDAY NIGHT AND WILL HELP CREATE
EVEN BETTER CHANCES FOR LIGHT SNOW.

SURFACE HIGH PRESSURE WILL BE OVER THE PLAINS THROUGH SATURDAY...
WITH A SOUTHEASTERLY SURFACE PRESSURE GRADIENT OVER THE CWA. THE
WEAK SURFACE FORCING AND ISENTROPIC UPGLIDE WILL ALSO HELP TO
PRODUCE THE CLOUDS AND LIGHT SNOW THROUGH SATURDAY. SURFACE
CYCLOGENESIS TAKES PLACE OVER SOUTHERN COLORADO SATURDAY NIGHT...
WITH SURFACE FORCING INCREASING.

BASED ON THE ABOVE...HAVE BUMPED UP POPS AND SNOW AMOUNTS FOR
MAINLY SATURDAY AND SATURDAY NIGHT OVER THE CWA. THE LOWER
ELEVATIONS MAY RECEIVE BETWEEN 1 AND 3 INCHES OF SNOW...WITH LARGER
AMOUNTS IN THE MOUNTAINS. OUTSIDE OF THE MOUNTAINS...MOST OF THE
SNOW WILL FALL SATURDAY AFTERNOON AND SATURDAY NIGHT. THE WARM
AIR ADVECTION IN THE MID LEVELS AND THE CLOUD COVER WILL HELP TO
SLOWLY MODERATE THE TEMPERATURES THROUGH 12Z SUNDAY.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 303 AM MST FRI DEC 6 2013

SUNDAY...SHORTWAVE TROUGH ALOFT MOVES FROM WESTERN COLORADO IN THE
MORNING TO NEBRASKA AND KANSAS IN THE AFTERNOON. AT LEAST A
SCATTERED COVERAGE OF LIGHT SNOW WILL OCCUR ACROSS OUR
COUNTIES...WITH A DECREASE IN COVERAGE IN THE AFTERNOON...THOUGH
STILL ENHANCED BY CYCLONIC FLOW ALOFT.

MONDAY...WINDY AND SLIGHTLY WARMER AS STRONG NORTHWEST FLOW ALOFT
DEVELOPS IN THE WAKE OF THE TROUGH ALOFT PASSAGE...PRODUCING STRONG
SURFACE TO 700 MB FLOW AND A STRENGTHENING SURFACE LEE TROUGH.

TUESDAY-THURSDAY...FLOW ALOFT GRADUALLY BACKS TO WEST...AND WITH
AIRMASS MODIFICATION AND RISING HEIGHTS AND THICKNESSES...WILL
FINALLY SEE TEMPERATURES MODERATE TO NEAR NORMAL. DRY PERIOD WITH
LIMITED LOW AND MID LEVEL MOISTURE AND MINIMAL LIFT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY MORNING)
ISSUED AT 1027 AM MST FRI DEC 6 2013

AREAS OF MAINLY MVFR CIGS WILL PERSIST INTO SATURDAY ACROSS THE AREA
WITH LIGHT SFC WINDS.  PATCHY FLURRIES AND FOG WILL ALSO CREATE SOME
MVFR/LCL IFR VISIBILITIES AT TIMES.

&&

.FIRE WEATHER...
ISSUED AT 303 AM MST FRI DEC 6 2013

FIRE WEATHER CONCERNS WILL BE MINIMAL THROUGH NEXT WEEK.
TEMPERATURES WILL BE WELL BELOW NORMAL THROUGH EARLY NEXT WEEK...
THEN READINGS WILL MODERATE TO AT OR ABOVE NORMAL STARTING ON
WEDNESDAY. THE WIDESPREAD SNOW COVER WILL PERSIST THROUGH THE EARLY
PART OF NEXT WEEK. STRONG WINDS WILL BE POSSIBLE IN AREAS ALONG
AND WEST OF THE LARAMIE RANGE ON MONDAY AND TUESDAY.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...

WY...NONE.
NE...NONE

&&

$$

SHORT TERM...WEILAND
LONG TERM...RUBIN
AVIATION...RE
FIRE WEATHER...WEILAND