FXUS65 KCYS 121130
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
430 AM MDT MST SAT DEC 12 2009
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT...
HIGH LEVEL MOISTURE HAS INCREASED OVER THE AREA AS A GENERAL ZONAL
FLOW IN PLACE ACROSS MUCH OF THE COUNTRY WITH SOME LEE ENHANCED
CLOUDS ACROSS THE EASTERN CWA. TWO SYSTEMS EXPECTED TO AFFECT THE
CWA OVER THE NEXT 48 HOURS. ONE BEING AN UPPER LOW WHICH WILL MOVE
ONSHORE ALONG THE CAL COAST THIS EVENING THEN OPEN AND ACCELERATE
EASTWARD ACROSS THE REGION SUNDAY. THE OTHER BEING AN ARCTIC COLD
FRONT WHICH WILL SLIP SOUTHWESTWARD TONIGHT AND SHOULD LIE SOMEWHERE
FROM EAST CENTRAL WY INTO THE SOUTHERN NEB PANHANDLE SUNDAY.
OBVIOUSLY POSITION OF THIS FRONT WILL BE CRITICAL FOR TEMPERATURES.
SOME LIGHT SNOWS ALSO EXPECTED TONIGHT THROUGH SUNDAY...MAINLY OVER
THE MTNS WITH THE UPPER SYSTEM AND OVER THE NORTHERN CWA IN
ASSOCIATION WITH THE FRONT. SNOWFALL AMOUNTS NOT EXPECTED TO BE
HIGH BUT AT LEAST A FEW INCHES OVER THE HIGHER MTNS. OTHERWISE
LOCALLY WINDY CONDITIONS WILL PERSIST OVER WIND PRONE AREAS TODAY
AND SUNDAY. ARCTIC FRONT SHOULD BEGIN TO PULL BACK EAST SUNDAY NIGHT
BUT STILL QUITE COLD OVER THE NORTHEAST PART OF THE NEBRASKA
PANHANDLE.
.LONG TERM...MONDAY THROUGH FRIDAY. DECEMBER 11TH 5PM MST ECMWF AND
GFS 500 MB SYNOPTIC PATTERNS SIMILAR...LEADING TO HIGH CONFIDENCE IN
THEIR RESPECTIVE MODEL SOLUTIONS.
MONDAY...STARK CONTRAST IN MAXIMUM TEMPERATURES FROM CHEYENNE TO
CHADRON AS SHALLOW ARCTIC AIRMASS WILL RESIDE ACROSS OUR EASTERN
COUNTIES. HIGH TEMPERATURES IN THE 30S TO LOWER 40S WEST OF THE
BOUNDARY...WITH TEENS AND 20S IN THE ARCTIC AIRMASS EAST OF THE COLD
FRONT. ISOLATED SNOW SHOWERS IN THE UPSLOPE REGIME IN THE ARCTIC
AIRMASS WITH SCATTERED TO NUMEROUS OROGRAPHIC SNOW SHOWERS ACROSS
THE SNOWY RANGE IN MOIST WEST FLOW ALOFT.
TUESDAY...TEMPERATURES NEAR CLIMATOLOGICAL NORMALS WITH HIGHS IN THE
20S AND 30S WITH 1000-500 MB THICKNESSES NEAR 5430 METERS AND
SIGNIFICANT AMOUNTS OF OPAQUE MIDDLE AND HIGH LEVEL CLOUDINESS
DOWNWIND OF A DIRTY RIDGE ALOFT ACROSS THE GREAT BASIN STATES.
OROGRAPHIC SNOW SHOWERS WILL REMAIN WEST OF THE SNOWY RANGE...AND
ACROSS FAR WESTERN WYOMING.
WEDNESDAY...WARMING TREND ON TAP AS 1000-500 MB THICKNESSES WARM TO
5520 METERS. HIGH TEMPERATURES IN THE 30S TO MIDDLE 40S...ASSUMING
MIDDLE AND HIGH CLOUD OPACITY IS MINIMAL.
THURSDAY...HIGH TEMPERATURES EVEN WARMER WITH 30S WEST TO 40S EAST
WITH 1000-500 MB THICKNESSES NEAR 5520 METERS...AND ASSUMING MINIMAL
AND NEGLIGIBLE OPACITY EFFECT FROM MIDDLE AND HIGH CLOUDS.
FRIDAY...MILD WEATHER TREND CONTINUES FROM THURSDAY WITH NORTHWEST
FLOW ALOFT...500 MB HEIGHTS NEAR 5730 METERS...1000-500 MB
THICKNESSES NEAR 5570 METERS AND MINIMAL OPACITY FROM MIDDLE AND
HIGH CLOUDS. HIGH TEMPERATURES FROM MID 30S ACROSS CARBON COUNTY
WYOMING TO UPPER 40S ACROSS FAR SOUTHEAST WYOMING AND MUCH OF
SOUTHWEST NEBRASKA.
&&
.AVIATION...VFR TODAY...EXCEPT FOR MVFR IN SCATTERED SNOW SHOWERS
ACROSS SOUTHWEST CARBON COUNTY AND THE SNOWY RANGE. SNOWY RANGE
MOUNTAINS OCCASIONALLY OBSCURED.
VFR TONIGHT...EXCEPT FOR IFR AND MVFR IN SNOW SHOWERS ACROSS CARBON
COUNTY AND IN LOW CLOUDS AND FOG EAST OF AN ARCTIC COLD FRONT FROM
DOUGLAS TO KIMBALL. MOUNTAINS OBSCURED.
VFR SUNDAY...EXCEPT FOR IFR AND MVFR IN SNOW SHOWERS...FOG AND LOW
CLOUDS NORTH OF A LARAMIE TO ALLIANCE LINE. MOUNTAINS OBSCURED.
&&
.FIRE WEATHER...NO CONCERNS ANTICIPATED THROUGH SUNDAY.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...RE
LONG TERM/AVIATION...RUBIN
