541
FXUS65 KCYS 090923
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
224 AM MST TUE FEB 9 2010
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
DRY AND WARMING WEATHER CAN BE EXPECTED OVER THE CWA FOR THIS PART OF
THE FORECAST. SURFACE HIGH PRESSURE CURRENTLY EXTENDS OVER THE
WESTERN DAKOTAS AND NEBRASKA AND WILL MOVE SLOWLY EAST TODAY. THE
TEMPERATURES EARLY THIS MORNING ARE CHILLY WITH WIND CHILL VALUES AS
OF 09Z MAINLY BETWEEN ZERO AND 20 BELOW ZERO. AS THE SURFACE HIGH
MOVES EAST...TEMPERATURES WILL REBOUND AND WILL BE MUCH WARMER THAN
MONDAY. THE 700 MB TEMPERATURES OVER THE CWA WARM TO AROUND -10C
FROM THE CURRENT -14C TO -18C. A SURFACE LOW PRESSURE TROUGH WILL
FORM OVER EASTERN WYOMING...WITH WESTERLY WINDS AND SOME MIXING
BEHIND THE FEATURE. THE NORTHWEST FLOW ALOFT WILL CONTINUE OVER
THE REGION THROUGH WEDNESDAY NIGHT AS THE CURRENT CALIFORNIA UPPER
LOW MOVES WELL TO THE SOUTH OF THE CWA AND A RIDGE ALOFT BUILDS
WEDNESDAY AND WEDNESDAY NIGHT OVER THE WESTERN PART OF THE NATION.
SEVERAL WEAK SHORTWAVE TROUGHS WITHIN THAT FLOW ALOFT WILL PRODUCE
AT LEAST A PARTLY CLOUDY SKY OVER THE WESTERN CWA STARTING TONIGHT.
SURFACE PRESSURE GRADIENT AND THE LOW LEVEL HEIGHT DIFFERENCES ACROSS
THE CWA WILL PRODUCE BRISK WINDS ALONG AND WEST OF THE LARAMIE RANGE
STARTING THIS AFTERNOON. TEMPERATURES WILL CONTINUE TO WARM ON
WEDNESDAY AS WESTERLY SURFACE WINDS WILL BE OVER THE ENTIRE CWA AND
EVEN LOW TEMPERATURES WILL MODERATE TONIGHT AND EVEN MORE SO WEDNESDAY
NIGHT DUE TO THE WINDS. THE GFS AND SREF DEVELOP LIGHT QPF OVER THE
SNOWY RANGE WEDNESDAY AND WEDNESDAY NIGHT WHILE THE OTHER MODELS ARE
DRY. WILL LOWER INHERITED POPS SOME OVER THE SNOWY RANGE DURING THAT
TIME AS GFS MOISTURE APPEARS TO BE OVERDONE. AS OF 09Z...THERE ARE
AREAS OF LOWER CLOUDS THAT HAVE SPREAD INTO WESTERN CARBON COUNTY...
SOUTHERN LARAMIE COUNTY AND TO THE EAST OF THE NORTHERN PANHANDLE.
BELIEVE THAT THE CLOUDS IN THOSE AREAS WILL NOT SPREAD MUCH AND WILL
BE GONE BY 16Z.
LONG TERM...THURSDAY THROUGH MONDAY
GENERALLY QUIET WEATHER PATTERN EXPECTED ACROSS THE REGION FOR MOST
OF THE PERIOD WITH SOMEWHAT COOL TEMPERATURES. WESTERN CONUS UPPER
RIDGE WILL REMAIN GENERALLY IN PLACE THROUGH THE WEEKEND THOUGH SOME
VARAIANCE IN STRENGTH AS SHOTS OF SHORTWAVE ENERGY RIDE ATOP THE
RIDGE BEFORE TURNING SE ACROSS THE PLAINS. THESE IMPULSES WILL
BRING PERIODS OF SNOW SHOWERS MAINLY TO THE HIGHER MTNS FOR MUCH OF
THE PERIOD WITH SOME POSSIBLY SPREADING OUT OVER THE PLAINS SAT
NIGHT AS AN UPPER LOW DROPS OUT OF SRN CANADA INTO THE UPPER MISS
RIVER VALLEY. SURGE OF COOLER AIR BEHIND THIS UPPER LOW SHOULD PUSH
A BACKDOOR FRONT AGAINST THE MTNS SUNDAY BEFORE RETREATING AGAIN
MONDAY.
AVIATION
MVFR OR IFR CEILINGS WILL CONTINUE THROUGH 16Z OVER THE
AIRPORTS AT KRWL...KCYS AND JUST TO THE NORTH AND EAST OF KCDR.
OTHERWISE VFR CONDITIONS WILL BE OVER THE CWA THROUGH 12Z THURSDAY.
THE HIGHER ELEVATIONS OF THE SNOWY RANGE WILL BE OBSCURED WEDNESDAY
AND WEDNESDAY NIGHT. WESTERLY SURFACE WINDS WILL GUST AS HIGH AS 30
KNOTS IN SOME AREAS ALONG AND WEST OF THE LARAMIE RANGE THIS AFTERNOON
AND CONTINUING THROUGH 12Z THURSDAY.
FIRE WEATHER
NO FIRE WEATHER CONCERNS THROUGH THE END OF THE WEEK.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
MSW/RE
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