000
FXUS65 KCYS 180946
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
246 AM MST TUE NOV 18 2008

.SHORT TERM...DRY CONDITIONS WILL CONTINUE ACROSS THE AREA THROUGH 
WEDNESDAY.  RECORD HIGH TEMPERATURES WILL OCCUR IN MOST LOCATIONS 
TODAY AS A THERMAL RIDGE MOVES OVER THE CWA.  A SURFACE COLD FRONT 
WILL BEGIN TO MOVE INTO THE NORTHERN PORTIONS OF THE CWA AROUND NOON 
ON WED...AND WILL BE SOUTH OF THE FORECAST AREA BY MIDNIGHT.  THE 
WESTERLY SURFACE WINDS WILL SHIFT TO THE EAST TO NORTHEAST AFTER 
FRONTAL PASSAGE.  SOME LOW AND MID LEVEL MOISTURE IS ASSOCIATED WITH 
THE FRONT AND LOW LEVEL UPSLOPE FLOW WILL RESULT IN A SLIGHT CHANCE 
OF SNOW...MAINLY EAST OF THE LARAMIE RANGE WED NIGHT.  THE BEST 
CHANCES OF SNOW WILL BE ACROSS CONVERSE AND NIOBRARA 
COUNTIES...HOWEVER ALL LOCATIONS WILL ONLY SEE LESS THAN AN INCH OF 
ACCUMULATION.  HIGH TEMPERATURES WILL BE FROM 25 TO 30 DEGREES ABOVE 
NORMAL TODAY...AND 10 TO 15 DEGREES ABOVE NORMAL FOR WED.

.LONG TERM...THURSDAY THROUGH MONDAY...
WILL AGAIN FOLLOW THE HPC SUGGESTION THAT THE EUROPEAN MODEL IS 
PRESENTING THE MOST REASONABLE SOLUTION FOR THE LONG TERM...ALTHOUGH 
THE EARLY PART OF THE PERIOD DOES HAVE INCREASING AGREEMENT FROM THE 
GFS...WRF-NMM AND EUROPEAN. A FAIRLY STRONG SHORT-WAVE WILL CREATE A 
BAROCLINIC ZONE ACROSS THE AREA AS IT KNOCKS DOWN THE UPPER RIDGE 
AND ALLOWS A SURFACE COLD FRONT TO BACK INTO THE AREA. AT THIS TIME 
WILL INCREASE PRECIPITATION CHANCES ACROSS THE AREA SLIGHTLY 
THURSDAY MORNING...WITH MOST OF THE FAVORABLE DYNAMICS MOVING TO THE 
SOUTH AND EAST BY AFTERNOON. TEMPERATURES WILL BE MUCH COOLER 
THURSDAY WITH MOST AREAS ALONG AND EAST OF THE LARAMIE RANGE 20 TO 
25 DEGREES COOLER THAN WEDNESDAY AND AROUND 10 DEGREES COOLER THAN 
NORMAL. AREAS FARTHER TO THE WEST WILL COOL TO NEAR NORMAL 
TEMPERATURES THURSDAY.

THURSDAY NIGHT AND INTO FRIDAY...THE GFS AND EUROPEAN SHOW A 
SHORT-WAVE DISTURBANCE ALOFT ACROSS THE NORTHERN ROCKIES. THE GFS IS 
MUCH FARTHER SOUTH AND MORE AMPLIFIED WITH THIS FEATURE. WILL 
CONTINUE RECENT TREND OF LEANING MORE ON THE EUROPEAN MODEL IDEA 
THAT THIS WAVE WILL BE WEAKER AND REMAIN NORTH OF THE FORECAST AREA 
FOR FRIDAY. FLOW ALOFT WILL BACK SLIGHTLY FRIDAY ALLOWING FOR A 
SLIGHT WARM-UP BACK TO NEAR NORMAL TEMPERATURES ACROSS THE AREA INTO 
SATURDAY. ANOTHER SHORT-WAVE ALOFT WILL CREST THE RIDGE ACROSS 
NORTHERN MONTANA SATURDAY...WITH A SURFACE COLD FRONT MOVING SOUTH 
THROUGH THE AREA SATURDAY NIGHT OR EARLY SUNDAY. HAVE INTRODUCED 
PRECIPITATION CHANCES ACROSS THE SOUTHERN TIER OF COUNTIES EARLY 
SUNDAY THROUGH SUNDAY NIGHT. TEMPERATURES SUNDAY AND INTO MONDAY CAN 
BE EXPECTED TO BE NEAR NORMAL TO SLIGHTLY BELOW NORMAL.

&&

.AVIATION...
VFR CONDITIONS THRU WED AS LARGE UPPER RIDGE DRIFTS ACROSS THE
REGION. A COLD FRONT MOVING DOWN FROM THE NORTH LATE AFTERNOON WED
THROUGH WED NIGHT WILL BRING LOW CLOUDS AND SOME LIGHT
SNOW...WHICH WILL RESULT IN AREAS OF MVFR AND LOCAL IFR
CONDITIONS...MAINLY EAST AND NORTH OF THE LARAMIE RANGE.

&&

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

&&

$$

SHORT TERM/AVIATION...KMD
LONG TERM...CARPENTER