FXUS65 KCYS 261017
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
315 AM MST THU NOV 26 2009
.SHORT TERM...TODAY THROUGH FRIDAY NIGHT...
MILD AND DRY WEATHER WILL BE OVER THE CWA THROUGH FRIDAY NIGHT.
HEIGHTS ALOFT WILL RISE OVER THE ROCKIES THROUGH FRIDAY MORNING WITH
THE RIDGE AXIS OVER THE CWA 12Z FRIDAY. TEMPERATURES WILL BE WELL
ABOVE NORMAL DURING THAT TIME AS 700 MB TEMPERATURES RISE TO 4C
THIS AFTERNOON AND BETWEEN 4C AND 6C TONIGHT AND FRIDAY. SOME
CIRRUS WILL SPILL OVER THE RIDGE AND OVER THE EAST PART OF THE CWA
TODAY. THEN SKIES WILL BE NEARLY CLOUD FREE TONIGHT BEFORE CIRRUS
STARTS TO SPREAD EAST BEHIND THE RIDGE AXIS FRIDAY AFTERNOON AND
FRIDAY NIGHT. THE MAIN WEATHER CONCERN FOR THIS PORTION OF THE
FORECAST WILL BE WINDS MAINLY ALONG AND WEST OF THE LARAMIE RANGE.
THE LOW LEVEL HEIGHT DIFFERENCE ACROSS THE CWA WILL REMAIN FAIRLY
LARGE THROUGH 12Z SATURDAY. WINDS AT 700 MB DECREASE SOME TODAY
AND TONIGHT...BUT THEN INCREASE ON FRIDAY. THE RESULT WILL BE A
CONTINUATION OF WESTERLY SURFACE WINDS GUSTING TO 40 MPH IN MANY
AREAS ALONG AND WEST OF THE LARAMIE RANGE THROUGH FRIDAY NIGHT.
CURRENT GUSTS AT KARL AND KBRX ARE BETWEEN 30 AND 40 MPH. THOSE
WINDS SHOULD DROP OFF SOME TODAY BEFORE INCREASING AGAIN ON FRIDAY.
HAPPY THANKSGIVING.
.LONG TERM...SATURDAY THROUGH WEDNESDAY
RELIED ON THE ECMWF FOR THE LONG TERM FORECAST. THE GFS...UKMET AND
ECMWF ARE ALL VERY SIMILAR EARLY ON...BUT THE GFS AND ECMWF DIFFER
TOWARDS THE END OF THE PERIOD WITH THE NEXT UPPER TROUGH MOVING OVER
THE WEST. SW FLOW WILL BE ALOFT SAT AS THE UPPER TROUGH CONTINUES
TO APPROACH THE AREA FROM THE WEST. HIGH TEMPS WILL BE
SIGNIFICANTLY COOLER SAT DUE TO THE COLD FRONT PASSAGE WHICH OCCURS
LATE FRIDAY NIGHT/EARLY SAT MORNING. THE UPPER TROUGH WILL BEGIN TO
MOVE ACROSS THE CWA SAT NIGHT AND WILL BE EAST OF THE FORECAST AREA
BY SUN EVENING. LIGHT SNOW WILL BEGIN WEST OF THE LARAMIE RANGE
SATURDAY AND WILL SPREAD ACROSS THE CWA SAT NIGHT BEFORE ENDING
SUNDAY MORNING. NO SIGNIFICANT ACCUMULATIONS ARE EXPECTED WITH THE
SNOW FALLING SPORADICALLY OVER THE AREA. ONLY A DUSTING TO A HALF
INCH IS EXPECTED AT THE LOWER ELEVATIONS...WITH A COUPLE INCHES IN
THE MOUNTAINS BY SUN MORNING. SUN WILL BE A COLD DAY AS THICKNESS
VALUES CONT TO DECREASE. TEMPERATURES WILL MODERATE ON MON WITH A
BRIEF UPPER RIDGE OVER THE FORECAST AREA. BRISK CONDITIONS WILL
ALSO OCCUR UNDER SUNNY SKIES. FOR TUES...HIGHS WILL BE SLIGHTLY
WARMER AS A LEE TROUGH SETS UP DURING THE DAY LEADING TO BRISK TO
WINDY CONDITIONS. A COLD FRONT WILL ENTER THE NORTHERN PORTION OF
THE CWA AS AN UPPER TROUGH FROM SOUTHERN CANADA/PAC NW HEADS TOWARDS
THE AREA. THE COLD FRONT WILL MOVE ACROSS THE CWA TUES NIGHT
RESULTING IN COLD TEMPERATURES AND A CHANCE OF SNOW ON WED. THIS IS
WHERE THE GFS AND ECMWF DIFFER WITH THE ECMWF CENTERING THE BROAD
UPPER TROUGH OVER THE WESTERN U.S. AND THE GFS CENTERS IT OVER THE
CENTRAL U.S. HIGH TEMPERATURES WILL BE AROUND NORMAL SAT...5
DEGREES BELOW NORMAL SUN...3 TO 5 DEGREES ABOVE NORMAL FOR MON AND
TUES...AND 5 TO 8 DEGREES BELOW NORMAL ON WED.
&&
.AVIATION...VFR CONDITIONS WILL CONTINUE THROUGH FRIDAY NIGHT.
WESTERLY SURFACE WINDS WILL GUST TO 30 KNOTS AT AT TIMES ALONG AND
WEST OF THE LARAMIE RANGE THROUGH 12Z SATURDAY. THOSE WINDS WILL
AFFECT AIRPORTS AT KRWL AND KEAN.
&&
.FIRE WEATHER...SURFACE WINDS WILL GUST AS HIGH AS 40 MPH AT TIMES
IN MANY AREAS ALONG AND WEST OF THE LARAMIE RANGE THROUGH FRIDAY
NIGHT. IN ADDITION...TEMPERATURES WILL BE WELL ABOVE NORMAL DURING
THAT TIME. MINIMUM RELATIVE HUMIDITIES OVER THE LOWER ELEVATIONS
WILL BE AROUND 25 PERCENT THIS AFTERNOON AND AROUND 20 PERCENT
FRIDAY AFTERNOON. STILL WEATHER CONDITIONS WILL STAY BELOW CRITICAL
LEVELS AND FUELS WILL NOT SUPPORT LARGE FIRE GROWTH AT THIS TIME.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
WEILAND/KMD
