Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 221156
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
556 AM MDT WED OCT 22 2014

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 253 AM MDT WED OCT 22 2014

CURRENT IR SATELLITE LOOP SHOWS THE UPPER LEVEL TROUGH AXIS
CURRENTLY OVER WESTERN WYOMING EARLY THIS MORNING WITH RADAR
SHOWING RAIN SHOWERS PUSHING NORTHEAST INTO WESTERN NEBRASKA.
DRIER AIR HAS ALREADY PUSHED INTO CASPER AT THIS HOUR...AND WILL
CONTINUE TO PUSH ACROSS EAST CENTRAL WYOMING AND THE NORTHERN
PANHANDLE TODAY. THIS DRIER AIR IS ALSO BEHIND THE MAIN COLD
FRONT...WHICH IS RATHER WEAK THIS MORNING BUT GENERALLY ACROSS
NORTHERN CARBON COUNTY EXTENDING NORTHEAST ACROSS CONVERSE AND
NIOBRARA COUNTIES. THIS COLD FRONT WILL CONTINUE TO PUSH SOUTHEAST
ACROSS THE REGION THIS MORNING AS THE TROUGH AXIS SWINGS THROUGH
THE AREA. TEMPERATURES WILL BE 5 TO 10 DEGREES COOLER ON
TODAY BEHIND THE FRONT...BUT WILL STILL BE SEASONABLE FOR THIS
TIME OF THE YEAR AND GENERALLY IN THE MID 50S TO MID 60S. KEPT POP
BELOW 15 PERCENT ON WEDNESDAY...BUT WILL HAVE TO WATCH THE I80
CORRIDOR NEAR THE COLORADO BORDER FOR SOME ISOLATED SHOWERS AND
PERHAPS A FEW LIGHTNING STRIKES DUE TO LLVL INSTABILITY AND THE
FRONT STALLING ACROSS THE COLORADO MOUNTAINS. THIS MAY PROVIDE
JUST ENOUGH CONVERGENCE TO TRIGGER A FEW AFTERNOON SHOWERS...BUT
KEPT POP BELOW 15 PERCENT ALONG I80 FOR NOW DUE TO LOW CONFIDENCE.

ANOTHER WARMING TREND IS EXPECTED TO BEGIN ON THURSDAY AS A BROAD
UPPER LEVEL RIDGE BEGINS TO EXTEND NORTHWARD ACROSS THE CENTRAL
ROCKY MOUNTAIN REGION. HIGH TEMPERATURES IN THE UPPER 60S TO UPPER
70S ARE EXPECTED LATE THIS WEEK...WITH A FEW LOWER ELEVATION
LOCATIONS BELOW 4500 FEET REACHING 80 DEGREES BY FRIDAY. POP WILL
BE NEAR ZERO BOTH THURSDAY AND FRIDAY WITH INTERVALS OF DENSE HIGH
CLOUDS POSSIBLE.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 300 AM MDT WED OCT 22 2014

MEDIUM RANGE GUIDANCE CONTINUES TO SHOW A BIG CHANGE IN THE
WEATHER IN THE EXTENDED.

STARTING OFF FRIDAY NIGHT INTO SATURDAY...CWFA UNDER AN UPPER
RIDGE. RIDGE AXIS PASSES OVER THE CWFA EARLY SATURDAY MORNING WITH
700MB WINDS INCREASING OUT OF THE WEST TO 30-35KTS. SATURDAY
SHOULD BE A BREEZY DAY. DOWNSLOPING OFF THE LARAMIE RANGE SHOULD
GIVE US SOME PRETTY WARM TEMPERATURES WITH MID TO UPPER 70S OUT IN
THE PANHANDLE AND LOW 70S OUT WEST.

STILL SOME DIFFERENCES BETWEEN THE GFS AND ECMWF FOR SUNDAY. ECMWF
SHOWS THE APPROACHING SHORTWAVE FURTHER SOUTH...TRACKING ACROSS
NORTHERN UTAH. GFS HAS THE SHORTWAVE TRACKING ACROSS WESTERN
MONTANA. BASED FORECAST OFF THE ECMWF AND HAVE SHOWERS DEVELOPING
OVER OUR WESTERN ZONES AS EARLY AS SUNDAY MORNING. SHOULD THE GFS
SOLUTION COME TRUE...WE WILL BE WINDY AND DRY.

MODELS ALSO DIFFER ON 700MB TEMPERATURES. WITH THE MORE NORTHERLY
TRACK...THE GFS IS FORECASTING 700MB TEMPERATURES OF +4 TO +10C
OVER THE CWFA FOR SUNDAY AFTERNOON. ECMWF SHOWING -2C TO +4C OVER
THE AREA. SO WE COULD SEE A PRETTY BIG CHANCE FOR A TEMPERATURE
BUST ON FORECAST HIGHS SUNDAY.

COLDER TEMPERATURES FOR MONDAY AS BOTH MODELS SHOW 700MB
TEMPERATURES RANGING FROM -4 TO -8C OVER SOUTHEAST WYOMING. SPLIT
FLOW WITH ENERGY FROM THE SHORTWAVE TRACKING INTO CENTRAL
COLORADO. BOTH MODELS SHOWING THIS FOR MONDAY. SINCE THIS IS QUITE
DIFFERENT FROM PREVIOUS MODEL RUNS...DECIDED TO KEEP LOW END
CHANCE POPS IN FOR ANOTHER FORECAST CYCLE BEFORE CHANGING THE
WEATHER DRASTICALLY. SHOULD BE COLD ENOUGH FOR MOST PRECIP TO FALL
AS SNOW FOR MOST OF MONDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 554 AM MDT WED OCT 22 2014

LATEST RADAR LOOP SHOWING SHOWERS COMING TO AN END OUT OVER THE
PANHANDLE. SHOULD SEE DRY CONDITIONS THE NEXT 24 HOURS WITH
SCATTERING CLOUDS THROUGH THE MORNING HOURS. VFR CONDITIONS
EXPECTED.

&&

.FIRE WEATHER...
ISSUED AT 153 AM MDT WED OCT 22 2014

MINIMAL FIRE WEATHER CONCERNS THIS WEEK AND THIS WEEKEND. DAYTIME
HUMIDITIES WILL LOWER INTO THE 15 TO 25 PERCENT RANGE TODAY AND
THURSDAY AS DRIER AIR PUSHES INTO THE AREA...BUT WINDS WILL BE
RELATIVELY LIGHT AND NOT MUCH OF A FACTOR. COOLER TEMPERATURES AND
HIGHER HUMIDITIES ARE EXPECTED BY LATE THIS WEEKEND.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...TJT
LONG TERM...CLAYCOMB
AVIATION...CLAYCOMB
FIRE WEATHER...TJT






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