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000
FXUS65 KCYS 100907
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
200 AM MST WED FEB 10 2010

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT...
MAINLY DRY AND QUIET WEATHER EXPECTED ACROSS THE CWA THROUGH
THURSDAY NIGHT UNDER NW FLOW ALOFT.  SOME SNOW SHOWERS SHOULD OCCUR
FROM TIME TO TIME OVER THE HIGHER MTNS AS A FEW WEAK IMPULSES IN THE
FLOW INTERACT WITH OROGRAPHICS BUT SNOWFALL AMOUNTS WILL BE LIGHT.
TEMPERATURES WILL TURN WARMER TODAY AS COLD SFC HIGH OVER THE
CENTRAL PLAINS SHIFTS EASTWARD AND WESTERLY DOWNSLOPE FLOW SPREADS
INTO THE HIGH PLAINS. MAXS A BIT WARMER ON THURSDAY AS THICKNESS
RIDGE MOVES OVER THE HIGH PLAINS BUT INCREASED CLOUD COVER SHOULD
ACT TO LIMIT WARMING SOMEWHAT.

.LONG TERM...FRIDAY THROUGH TUESDAY...
MODELS DIFFER FOR THIS PART OF THE FORECAST MAINLY IN REGARDS TO
TIMING OF THE SHORTWAVE TROUGHS AND THEIR MOISTURE.  HOWEVER...THERE
ARE SOME GENERAL AGREEMENTS FROM MODELS.  THE MEAN RIDGE OVER THE
WESTERN PART OF THE NATION IS THE MAIN SYNOPTIC FEATURE.  THE RIDGE
AXIS MOVES FROM THE ALONG THE WEST COAST TO OVER THE ROCKIES AND
BACK FROM FRIDAY THROUGH TUESDAY AS SHORTWAVE TROUGHS MOVE OVER THE
REGION ON THE EAST SIDE OF THE RIDGE.  THAT WILL RESULT IN A GENERAL
NORTHWEST WIND FLOW ALOFT OVER THE CWA.  THE OTHER SIMILARITY IS THE
SIGNIFICANT SHORTWAVE TROUGH WHICH MOVES OVER THE PLAINS SATURDAY
THROUGH SUNDAY.  THE SHORTWAVE TROUGH MOVES A CANADIAN POLAR COLD
FRONT TO AT LEAST THE LARAMIE RANGE SATURDAY AND SATURDAY EVENING.
THE 00Z GFS HAS MORE MOISTURE FROM FORECAST RAOBS OVER THE CWA THAN
THE OTHER MODELS THROUGH THIS PART OF THE FORECAST.  THAT RESULTS IN
GENERALLY MORE WIDESPREAD QPF THAN OTHER MODELS FRIDAY THROUGH
SATURDAY NIGHT AND ESPECIALLY ON MONDAY AND EARLY MONDAY NIGHT.  ON
FRIDAY...MODELS DO INCREASE MAINLY THE MID LEVEL MOISTURE AND A
REMAINING SURFACE BOUNDARY WILL BE ALONG THE LARAMIE RANGE.  IN
ADDITION...THE MODELS DEPICT SOME JET DYNAMICS OVER THE CWA.  AT
THIS TIME WILL BUMP UP POPS A BIT FOR FRIDAY.  MAIN THREAT OF LIGHT
SNOW WOULD SEEM TO BE BEHIND THE CANADIAN POLAR FRONT THROUGH
SATURDAY NIGHT.  DEEPER LOW LEVEL MOISTURE SATURDAY AND SATURDAY
NIGHT LOOKS TO BE OVER THE NORTHEAST THIRD OF THE CWA AND OVER THE
FAR WEST PART OF THE CWA AND WILL PLACE THE HIGHER POPS IN THOSE
AREAS.  GFS MOVES ANOTHER SHORTWAVE TROUGH ACROSS THE REGION ON
MONDAY AND EARLY MONDAY NIGHT.  MEANWHILE THE 12Z ECMWF HAS A MUCH
WEAKER SHORTWAVE TROUGH WITH A WEAKENING TREND FROM ITS EARLIER RUN.
THE ECMWF RIDGE AXIS ALOFT IS ALSO FURTHER EAST THAN THE GFS.  FOR
NOW WILL LEAN TOWARD THE 12Z ECMWF FOR THIS FORECAST AND KEEPING THE
CWA MAINLY DRY.  MODELS MOVE ANOTHER SHORTWAVE TROUGH OVER THE
REGION TUESDAY NIGHT AND WEDNESDAY WITH TIMING DIFFERENCES BETWEEN
MODELS AND FROM RUN TO RUN.  TEMPERATURES LOOK TO BE AT OR JUST
ABOVE NORMAL FOR FRIDAY THROUGH TUESDAY.  THE COLDEST DAY AT THIS
TIME APPEARS TO BE ON SUNDAY AND WILL GO BELOW GUIDANCE.

&&

.AVIATION...
VFR CONDITIONS EXPECTED THROUGH TONIGHT.

&&

.FIRE WEATHER...
NO FIRE WEATHER CONCERNS THROUGH THURSDAY.

&&

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

&&

$$

EMANUEL/WEILAND