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000
FXUS65 KCYS 092045
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
145 PM MST TUE FEB 9 2010

.SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT...
QUIESCENT PERIOD UNDER NORTHWEST FLOW ALOFT.

TONIGHT...NOT AS COLD AS LAST NIGHT AS THE ARCTIC AIR MODERATES AND
BEGINS RETREATING EAST. DECENT LOW LEVEL WINDS AND MIXING WILL LIMIT
COOLING POTENTIAL. LOCALLY WARMER TEMPERATURES TO THE LEE OF THE
LARAMIE RANGE FROM WHEATLAND TO THE COLORADO STATE LINE WITH WEST
WINDS AND DOWNSLOPE WARMING.

WEDNESDAY...WARMER DAY WITH HIGH TEMPERATURES FROM THE MID 20S TO
MID 30S WITH DOWNSLOPE WIND WARMING...1000-500 MB THICKNESSES NEAR
5370 METERS AND 700 MB TEMPERATURES NEAR -9 CELSIUS. ENOUGH LOW AND
MID LEVEL MOISTURE FOR ISOLATED TO SCATTERED OROGRAPHIC SNOW SHOWERS
ACROSS THE SNOWY RANGE...DRY ELSEWHERE.

WEDNESDAY NIGHT...NOT AS COLD AS TONIGHT WITH DECENT LOW LEVEL WINDS
AND MIXING. LOCALLY WARMER NIGHTTIME MINIMUM TEMPERATURES AGAIN FROM
WHEATLAND TO THE COLORADO STATE LINE DUE TO DOWNSLOPE WINDS AND
MIXING.

THURSDAY...FAST MOVING LOW AMPLITUDE SHORTWAVE TROUGH SKIMS
SOUTHEAST ACROSS THE DAKOTAS WITH NEGLIGIBLE EFFECTS ACROSS OUR
COUNTIES DUE TO DRY LOW AND MID LEVELS. WILL SEE WINDS INCREASING IN
THE WAKE OF THE SHORTWAVE PASSAGE...THOUGH GRADIENTS LOOK TOO WEAK
FOR WINDS TO BECOME TOO STRONG. HIGH TEMPERATURES IN THE UPPER 20S
TO NEAR 40 DEGREES WITH 1000-500 MB THICKNESSES NEAR 5400 METERS.
FEW OROGRAPHIC SNOW SHOWERS AGAIN IN THE SNOWY RANGE ON MOIST
NORTHWEST FLOW ALOFT.

.LONG TERM...THURSDAY THROUGH TUESDAY...
MEAN UPPER RIDGING ACROSS THE SOUTHWEST CONUS WILL MAINTAIN
PERSISTENT NORTHWEST FLOW ATOP THE CWA THROUGH THE PERIOD. NORTH
OF THIS UPPER LEVEL RIDGE...FLOW WILL BE FAIRLY PROGRESSIVE
ALLOWING NUMEROUS EMBEDDED SHORTWAVES TO PASS THROUGH THE AREA.
AS IS TYPICALLY THE CASE...MEDIUM RANGE GUIDANCE STRUGGLES ON THE
TIMING OF THESE SHORTWAVES WITHIN THIS PROGRESSIVE NORTHWEST FLOW.

INITIALLY...09/12Z MODEL SUITES HAVE TRENDED FURTHER SOUTH WITH
THE FOUR CORNERS LOW COMPARED TO THOSE OF 24 HOURS AGO. THIS LOW
WILL NOW PASS THROUGH NRN OLD MEXICO. ALTHOUGH TIMING DIFFERENCES
EXIST...FIRST EMBEDDED SHORTWAVE WILL PASS THROUGH THE AREA LATE
THURSDAY AND FRIDAY. LOWER ELEVATIONS WILL REMAIN DRY...WHILE THE
HIGHER MOUNTAINS WILL SEE INCREASED SNOW CHANCES. THE GFS/ECMWF
ARE CONSISTENT IN PAINTING A BIT OF STRONGER SHORTWAVE FOR
SATURDAY/SATURDAY NIGHT. IT LOOKS TO BE MAINLY ANOTHER MOUNTAIN
EVENT...BUT DID SPREAD SOME OUT SNOW CHANCES OUT ONTO THE PLAINS
AS WELL. CONDITIONS SHOULD APPROVE SOME FOR SUNDAY THROUGH
TUESDAY...AS HEIGHTS ARE ANTICIPATED TO BUILD. TEMPERATURES WILL
HOLD RIGHT AROUND SEASONAL NORMALS THROUGH THE PERIOD WITH HIGH
TEMPERATURES IN THE UPPER 30S/LOW 40S EAST OF THE MOUNTAINS...AND
MID 30S WEST.

&&

.AVIATION...
DRY NORTHWEST FLOW WILL PERSIST ACROSS AREA TERMINALS...THUS
CONDITIONS WILL REMAIN VFR THROUGH WEDNESDAY. SOUTHWEST WINDS OF
20 TO 25 MPH WILL GUST TO 35 MPH ACROSS THE WIND CORRIDOR...
INCLUDING KRWL THROUGH THIS EVENING BEFORE TAPERING OFF SOME WITH
SUNSET.

&&

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

&&

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

&&

$$

SHORT TERM/AVIATION...RUBIN
LONG TERM...HAHN