FXUS65 KCYS 271150
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
450 AM MST FRI NOV 27 2009

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT...UPPER RIDGE WILL 
BRING ONE MORE DAY OF WELL ABOVE SEASONAL TEMPS TODAY. IT WILL BE
WINDY AGAIN ALONG AND WEST OF I-25 WITH GUSTS NEAR 50 MPH AT THE
USUAL WIND PRONE SPOTS. PER SATELLITE LOOP... THERE WILL BE MORE
HIGH LEVEL CLOUDS TODAY...ESPECIALLY OVER NORTHERN AND WESTERN
CWA. FLOW ALOFT BACKS TO WSW LATE THIS AFTERNOON AND TONIGHT AS
THE SPLITTING UPPER TROUGH APPROACHES. MODELS ARE IN FAIRLY GOOD
AGREEMENT IN THE HANDLING THIS UPPER TROUGH WITH MAIN ENERGY
BECOMING ORGANIZED INTO AN UPPER LOW WAY TO OUR SOUTHWEST OVER
SOUTHERN CA WHILE WEAKER NORTHERN STREAM EVENTUALLY AFFECTS US. A
COLD FRONT WILL SLOWLY MOVE FROM NORTH TO SOUTH ACROSS THE CWA
FRIDAY NIGHT WITH UPSLOPE NORTH WINDS DEVELOPING BEHIND IT. THE
COMBINATION OF THE UPSLOPE LOW LEVEL FLOW AND SOME UPPER DYNAMICS
WILL CAUSE A BAND OF LIGHT SNOW TO DEVELOP. WHILE THIS BAND MAY
YIELD SOME DECENT AMOUNTS OVER PARTS OF SOUTHERN MT AND NORTHERN
WY...IT WILL BE WEAKENING AS IT SHIFTS SOUTH TOWARD US.
STILL...THERE WILL BE AT LEAST SCATTERED AREAS OF LIGHT SNOW
SPREADING FROM NORTH TO SOUTH OVER THE CWA SATURDAY AND SATURDAY
EVENING WITH A COUPLE INCHES POSSIBLE IN THE MOUNTAINS NEAR THE
SOUTHERN WY BORDER. FLOW ALOFT WILL VEER TO NW BEHIND UPPER TROUGH
IN THE NORTHERN STREAM SATURDAY NIGHT... AND CONDITIONS WILL
GRADUALLY IMPROVE FROM NORTH TO SOUTH LATE.

.LONG TERM...SUNDAY THROUGH THURSDAY NIGHT...MODELS IN GOOD
AGREEMENT THROUGH MONDAY NIGHT...AND THEN SOLUTIONS DIVERGE
SIGNIFICANTLY BY THE MIDDLE OF NEXT WEEK WITH SEVERAL MODELS
SHOWING A POSSIBLE ARCTIC OUTBREAK ACROSS SOUTHEAST WYOMING AND
THE NEBRASKA PANHANDLE. FOR LATER THIS WEEKEND...A WEAK UPPER
LEVEL TROUGH WILL PUSH EAST OF THE REGION SUNDAY WITH MOST OF THE
ENERGY REMAINING WELL SOUTH OF THE AREA ALONG WITH THE BEST CHC FOR
PRECIP. COOL NORTHWEST FLOW IS EXPECTED LATE IN THE WEEKEND AS A
RIDGE OF HIGH PRESSURE BUILDS OVER THE GREAT BASIN REGION
NORTHWARD INTO THE NRN ROCKIES...WITH HIGHS IN THE 30S AND LOWS IN
THE SINGLE DIGITS AND TEENS. MODELS THEN SHOW WINDS BACKING ALOFT
AS A FAST MOVING ARCTIC TROUGH PUSHES INTO THE PACIFIC
NORTHWEST...WITH WARMER WESTERLY FLOW OVER THE FRONT RANGE WITH
HIGHS WARMING INTO THE LOW 40S...TO AROUND 50 OVER THE NEBRASKA
PANHANDLE ON MONDAY. THERE IS CONSIDERABLE DISAGREEMENT BETWEEN
THE ECMWF AND GEM COMPARED TO THE GFS AND DGEX SOLUTIONS REGARDING
THE PATH OF THE ARCTIC AIRMASS. THE ECMWF AND GEM SHOW THE DEEP
UPPER LEVEL TROUGH MOVING ACROSS THE NRN ROCKIES AND THEN DIGGING
SOUTHWARD ALONG THE FRONT RANGE...WITH VERY COLD TEMPS AND SNOW
PUSHING INTO SOUTHEAST WYOMING AND THE NEBRASKA PANHANDLE AS 700MB
TEMPS LOWERING TO BELOW -20C AND SURFACE TEMPS AS LOW AS THE LOW
TO UPPER TEENS ALONG AND EAST OF THE LARAMIE RANGE. THE GFS AND
MOST OF THE GFS ENSEMBLE MEMBERS ARE THE OUTLIER...SHOWING THE
TROUGH AND ASSOCIATED ARCTIC AIRMASS PUSHING EASTWARD ALONG THE
CANADIAN BORDER WELL NORTH OF WYOMING. PREFER THE GEM AND
ECMWF...ALTHOUGH THE GEM IS 12 HOURS QUICKER WITH THE ARCTIC FRONT
PUSHING ACROSS THE SE WYOMING AND THE NEBRASKA PANHANDLE.
CONTINUED TO LOWER TEMPERATURES TUESDAY NIGHT THROUGH
THURSDAY...WITH HIGHS GENERALLY IN THE 30S AND LOWS IN THE SINGLE
DIGITS AND TEENS. HOWEVER...DID NOT GO AS LOW AS THE GEM AND ECMWF
SUGGESTED...WITH HIGHS STRUGGLING TO REACH 20 WEDNESDAY AND
THURSDAY AND LOWS POSSIBLY AROUND ZERO OR SLIGHTLY BELOW.
INCREASED POP ON WEDNESDAY AS THE FRONTAL BOUNDARY PUSHES ACROSS
THE AREA WITH MODELS SHOWING SOME LIGHT SNOW ACCUMULATIONS. &&

.AVIATION...VFR CONDITIONS EXPECTED TO CONTINUE THROUGH THIS 
EVENING WITH MOSTLY CLEAR SKIES. WEST WINDS WILL INCREASE LATER
THIS MORNING TO 15 TO 25 KTS WITH GUSTS AROUND 35 KTS
POSSIBLE...BUT WILL DIMINISH BY THIS EVENING. 
&&

.FIRE WEATHER...THERE WILL BE INCREASED FIRE DANGER POTENTIAL ALONG
AND WEST OF INTERSTATE 25 TODAY AS WEST WINDS GUST NEAR 50 MPH IN
PLACES WITH MINIMUM HUMIDITIES FROM 10 TO 15 PERCENT. FUELS DO NOT
SUPPORT LARGE FIRE GROWTH THOUGH AT THIS TIME. CONDITIONS WILL 
IMPROVE FRIDAY NIGHT AND SATURDAY AS NEXT SYSTEM MOVES IN WITH A
NORTH TO SOUTH COLD FRONTAL PASSAGE DURING FRIDAY NIGHT. 
&&

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

&&

$$

SHORT TERM/FIRE WEATHER...JLH 
LONG TERM/AVIATION...TJT