672 
FXUS65 KCYS 302001
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
200 PM MDT FRI APR 30 2004

.SHORT TERM...UPPER LOW OVER FOUR CORNERS WILL LOSE ITS GRIP OVER 
THE SOUTHEAST CORNER OF WY AND THE SOUTHERN-MOST TIER OF COUNTIES IN 
THE WESTERN NEBRASKA PANAHANDLE DURING THE EVENING.  STILL ENOUGH 
MOISTURE FOR SOME LOW CLOUDS OR FLURRIES IN THE SOUTHERN NEBRASKA 
PANHANDLE UNTIL DEFORMATION ZONES MAKES IT ALL THE WAY INTO 
COLORADO.  ATTENTION THEN TURNS TO NORTHERN STREAM TROF/SURFACE 
COLD FRONT DROPPING FROM MT INTO PARTS OF THE PANHANDLE LATER 
TONIGHT.  HAVE OPTED TO STAY DRY IN WY.  FRONTOGENESIS OVER THE 
PLAINS SHOWN BY PREVIOUS MODEL RUNS HAVE BACKED OFF IN 12Z RUN.  
UPSTREAM RADARS AND SURFACE OBS HAVE NOT SHOWN MUCH IN THE WAY OF 
PRECIP...JUST SOME MID AND HIGH LEVEL CLOUD DECKS.  ONLY PLACE THAT 
MENTIONED PRECIP WAS A SMALL PART OF SIOUX AND DAWES 
COUNTIES...WHICH IS CLOSER TO DYNAMICS AND COLDER TEMPS ALOFT.  NOT 
MUCH PRECIP FORMED UNTIL AFTERNOON HEATING CRANKED OVER LAPSE 
RATES...SO THINK PRECIP CHANCES PRETTY SMALL FOR JUST A SHORT PERIOD 
AFTER SUNSET. ONLY OTHER PLACE WORTH MENTIONING SMALL CHANCE OF 
PRECIP IS IN THE SNOWY RANGE DUE TO OROGRAPHY.  

TEMPERATURES TONIGHT WILL GENERALLY BE IN THE 20S AND 30S...THEN 
WARM UP INTO THE 40S AND 50S MOST AREAS.   /BANN/

.LONG TERM...WARM WEATHER OUTDOOR ENTHUSIASTS WILL ENJOY THE FIRST 
WEEK OF MAY. SUN...NWLY FLOW ALOFT PREVAILS. WILL TREND TOWARDS THE 
WARMER GUIDANCE HIGHS PER 850 MB TEMPS. MON...FLOW ALOFT BACKS TO 
WNWLY WITH 500 MB HEIGHTS AOA (AT OR ABOVE) 579 DEKAMETERS. GFS MEX 
MOS HIGHS LOOK ABOUT 5F TOO COOL PER 850 MB TEMPS NEAR 23C AND WEAK 
LOW LEVEL DOWNSLOPE. TUE...SUBTLE LOW LEVEL WIND SHIFT TO UPSLOPE 
COMPONENT ON THE PLAINS INDICATED BY GFS. HOWEVER...GFS HIGHS LOOK 
TOO COOL PER 850 MB TEMPS. CINCO DE MAYO...LOW LEVEL FLOW BECOMES 
WLY AS LOW AMPLITUDE MID LEVEL RIDGE AXIS SHIFTS EWRD ACROSS THE 
ROCKIES. WITH 850 MB TEMPS AOA 24C AND PLENTY OF SUNSHINE...GFS MEX 
MOS HIGHS LOOK 5-10F TOO COOL. THU...FLOW BECOMES MORE SWLY INDUCING 
EVEN WARMER TEMPERATURES. WITH 850 MB TEMPS PROGGED AOA 26C 
(79F)...GFS MEX MOS HIGHS LOOK 10F TOO COOL. FRI...STILL QUITE WARM 
WITH SWLY FLOW ALOFT...500 MB HEIGHTS AOA 576 DEKAMETERS AND 850 MB 
TEMPS AOA 25C (77F). GFS MEX MOS HIGHS LIKELY 10-15F TOO COOL WITH 
DECENT LOW LEVEL SWLY WINDS AND PLENTY OF SUNSHINE.    /RUBIN/

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