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000
FXUS65 KCYS 041734
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1034 AM MST WED DEC 4 2013

.UPDATE...
ISSUED AT 1031 AM MST WED DEC 4 2013

LATEST RADAR MOSAIC SHOWING SNOW REALLY TAPERING OFF. BUT WE STILL
HAVE SOME PRETTY STRONG WINDS EAST OF THE LARAMIE RANGE THIS
AFTERNOON. LATEST WYDOT WEBCAMS SHOWING SHARPLY REDUCED
VISIBILITIES. SINCE THE WINTER STORM WARNING WAS GOING TO
EXPIRE...WENT AHEAD AND ISSUED A BLOWING SNOW ADVISORY FOR THE
REST OF THE AFTERNOON. UPDATES SENT.

UPDATE ISSUED AT 847 AM MST WED DEC 4 2013

WENT AHEAD AND STARTED CANCELLING WESTERN PORTIONS OF THE WINTER
STORM WARNING THIS MORNING. WYDOT WEBCAMS SHOWING FAIRLY GOOD
VISIBILITIES OUT BY RAWLINS. RADAR SHOWING HEAVIEST BANDS OF SNOW
EAST OF THE LARAMIE RANGE AND IR SATELLITE SHOWING COLDEST TOPS
NOW OUT OVER THE PANHANDLE...DOWN TO CHEYENNE. MAY NEED TO EXTEND
THE WARNING OUT IN THE PANHANDLE IF THE MODERATE SNOW CONTINUES.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY NIGHT)
ISSUED AT 326 AM MST WED DEC 4 2013

THE SNOW...COLD AND BRISK WINDS CONTINUE EARLY THIS MORNING OVER
THE CWA. THE WINTRY WEATHER WILL LAST TODAY WITH THE COLD LASTING
TO 12Z FRIDAY AND BEYOND.

THE UPPER LEVEL CIRCULATION CURRENTLY OVER EASTERN MONTANA AND
NORTHWEST WYOMING IS SLOWLY FILLING AND BECOMING MORE ELONGATED.
THAT TREND WILL CONTINUE AS THE FEATURE MOVES EAST AND OVER THE
PLAINS TODAY THIS EVENING. AT THE SURFACE...UPSLOPE WINDS WILL
WEAKEN OVER THE AREA TODAY AS HIGH PRESSURE BUILDS INTO THE CWA
FROM THE NORTH. THE 300 MB JET WHICH IS CURRENTLY IN A FAVORABLE
POSITION FOR SYNOPTIC LIFT WILL SLOWLY MOVE SOUTHEAST AHEAD OF THE
UPPER LEVEL TROUGH AXIS. AT THE SAME TIME...MID LEVEL TEMPERATURES
CONTINUE TO COOL AND BEOME TOO COOL FOR FAVORABLE DENDRITIC
GROWTH. AS THE DYNAMICS WEAKEN OVER THE CWA TODAY...THE SNOW WILL
GRADUALLY TAPER OFF BEFORE GENERALLY ENDING EARLY TONIGHT. THROUGH
MID MORNING...A BAND OF HEAVIER SNOW FROM SOUTHWEST OF KCYS TO
NEAR KBFF WILL PERSIST WITH HIGHER HOURLY SNOWFALL RATES. IN GENERAL
AN ADDITIONAL 1 TO 3 INCHES OF SNOW WILL FALL THROUGH MIDDAY. WITH
THE SNOWFALL TAPERING OFF AS THE DAY GOES ON...WITH MOVE UP THE
EXPIRATION TIME OF THE CURRENT HIGHLIGHTS TO 19Z.

NORTHERLY SURFACE WINDS WILL GUST AS HIGH AS 30 OR 35 MPH TODAY
OVER MAINLY THE EAST PART OF THE CWA. THAT WILL HELP KEEP WIND
CHILL VALUES BETWEEN 20 BELOW ZERO AND 10 BELOW ZERO TODAY. THE
AMBIENT TEMPERATURES WILL NOT RISE MUCH TODAY AND HIGHS GENERALLY
IN THE SINGLE DIGITS.

COLD WILL THEN BE THE MAIN WEATHER MESSAGE FOR TONIGHT THROUGH
THURSDAY NIGHT OVER THE CWA. HIGHS ON THURSDAY WILL STILL BE IN THE
SINGLE DIGITS. LOWS WILL BE WELL BELOW ZERO AND WILL DEPEND ON THE
AMOUNT OF CLOUD COVER. THE SURFACE HIGH MOVES OVER THE CWA TONIGHT
AND THEN MOVES SLOWLY EAST AND OVER THE PLAINS. MEANWHILE...
MODELS MOVE ANOTHER SHORTWAVE TROUGH OVER THE CWA THURSDAY AND
THURSDAY NIGHT. THE ADDED MOISTURE AND WEAK LIFT MAY HELP CLOUDS
AND EVEN SOME FLURRIES TO FORM OVER THE THE SOUTHWEST HALF OF THE
CWA THURSDAY AND THURSDAY NIGHT. THAT SHOULD MAKE TONIGHT THE
COLDEST NIGHT...WITH LOWS AS COLD AS NEAR 30 BELOW ZERO IN THE
LARAMIE VALLEY. WITH THAT IN MIND...EXPECTED WIND CHILL VALUES
WILL BE AS LOW AS 45 BELOW ZERO IN THAT AREA. LATER SHIFTS MAY BEED
TO CONSIDER A WIND CHILL HIGHLIGHT FOR TONIGHT IN PARTS OF THE
CWA.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 326 AM MST WED DEC 4 2013

FRIDAY...DESPITE ZONAL FLOW ALOFT...STILL QUITE COLD WITH COLD
MASSIVE SURFACE HIGH PRESSURE PREVAILING ACROSS THE NORTHERN
ROCKIES...KEEPING COLD AIR BANKED UP TO THE MOUNTAINS. ALTHOUGH THE
ATMOSPHERE REMAINS MOIST...MINIMAL LIFT WILL PRODUCE LITTLE IN THE
WAY OF SNOW.

SATURDAY...DIGGING SHORTWAVE TROUGH ALOFT APPROACHING FROM WESTERN
COLORADO WILL HELP SPREAD LIGHT SNOW ACROSS OUR COUNTIES...THOUGH
ACCUMULATIONS LOOK MINIMAL WITH LIMITED LOW AND MID LEVEL MOISTURE
AND COLD AIR HOLDING LITTLE MOISTURE.

SUNDAY...DIMINISHING SNOW CHANCES...THOUGH CYCLONIC FLOW ALOFT WILL
HELP GENERATE AT LEAST A SLIGHT CHANCE OF SNOW SHOWERS. CONTINUED
QUITE COLD WITH CLOUD COVER AND PROGGED THICKNESSES AND 700 MB
TEMPERATURES.

MONDAY...COLD AND WINDY AS BRISK NORTHWEST FLOW ALOFT PREVAILS...
PRODUCING A RELATIVELY STRONG SURFACE TO 700 MB GRADIENT.

TUESDAY...NORTHWEST FLOW ALOFT CONTINUES...THOUGH WITH SLIGHT
AIRMASS MODIFICATION AS HEIGHTS ALOFT AND THICKNESSES SLOWLY RISE.
SNOW CHANCES QUITE SLIM WITH LACK OF LOW AND MID LEVEL MOISTURE AND
LIMITED LIFT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY MORNING)
ISSUED AT 1035 AM MST WED DEC 4 2013

SNOW WILL TAPER OFF THIS AFTERNOON WITH IFR VSBYS AND MAINLY MVFR
CIGS GRADUALLY IMPROVING TO VFR BY THIS EVENING...AND CONTINUING VFR
INTO THURSDAY.  GUSTY SFC WINDS EAST OF THE MTNS THIS AFTERNOON WILL
DIMINISH AROUND SUNSET.


&&

.FIRE WEATHER...
ISSUED AT 326 AM MST WED DEC 4 2013

FIRE WEATHER CONCERNS WILL BE MINIMAL THROUGH EARLY NEXT WEEK.
TEMPERATURES WILL BE VERY COLD DURING THAT TIME ALONG WITH
PERIODS OF SNOW TODAY. NORTHERLY SURFACE WINDS WILL GUST AS HIGH
AS 35 MPH TODAY OVER AREAS EAST OF THE LARAMIE RANGE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR WYZ102-
     106>108-115>119.

NE...WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR NEZ002-
     003-019>021-054-095-096.

&&

$$

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