FXUS65 KBOU 030936
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
230 AM MST THU DEC 03 2009

.SHORT TERM...NRN CO WILL REMAIN IN COLD NNW FLOW ALOFT THRU 
TONIGHT.  SOME LINGERING LIGHT SNOW EARLY THIS MORNING IS OCCURRING 
IN THE SWRN SUBURBS OF DENVER AND OVER THE PALMER DIVIDE AS A 
SECONDARY SURGE OF COLD AIR HAS MOVED ACROSS THE AREA.  THIS 
ACTIVITY HAS SLOWLY BEEN DIMINISHING ON RADAR AND IF THIS TREND 
CONTINUES MAY REDUCE POPS TO CHC CATEGORY FOR THE MID TO LATE 
MORNING HOURS.  ANY ADDITIONAL ACCUMULATIONS WILL BE VERY LIGHT.  
FOR THIS AFTN PCPN CHANCES LOOK LOW ALTHOUGH WITH LAPSE RATES IN THE 
6-7 C/KM RANGE AND LINGERING MOISTURE COULD SEE SOME SCT -SHSN DVLP 
BY LATE AFTN AND LINGER INTO THE EARLY EVENING HOURS IN AN NR 
FOOTHILLS MAINLY TO THE WEST AND SOUTH OF DENVER.  IN THE MTNS 
OROGRAPHICS ARE WEAK HOWEVER SO WILL ONLY MENTION SCT -SHSN.  TEMPS 
TODAY WILL REMAIN VERY COLD.  700 MB READINGS ARE FCST AROUND -20C 
WHICH WOULD ONLY ALLOW FOR HIGHS IN THE UPPER TEENS TO LOWER 20S 
ACROSS NERN CO.  FOR TONIGHT WITH LIGHT WINDS AND DECREASING CLOUDS 
OVERNIGHT LOWS COULD DROP A FEW DEGREES BELOW ZERO ACROSS PORTIONS 
OF NERN CO WITH WELL BELOW ZERO READINGS IN THE MTNS...FOOTHILLS AND 
HIGHER VALLEYS.      

.LONG TERM...THERE WILL BE A MODERATE NORTHERLY FLOW ALOFT ACROSS 
COLORADO ON FRIDAY AS RIDGING ALOFT BUILDS IN FROM THE NORTHERN 
ROCKIES. THE AIRMASS ON FRIDAY WILL BE DRY AND STABLE. THERE WILL BE 
SOME MODERATION ON TEMPERATURES BY FRIDAY AFTERNOON WITH SOME 
DOWNSLOPING FLOW DEVELOPING. AS THE NEXT UPPER LEVEL TROF DIGS INTO 
THE NORTHERN GREAT BASIN...THE FLOW ALOFT WITH STRENGTHEN FROM THE 
W-SW ON FRIDAY NIGHT AND SATURDAY. NAM CROSS SECTIONS SHOWING A 
MOUNTAIN WAVE DEVELOPING WITH CROSS BARRIER FLOW OF 40-45KT. AT THIS 
TIME LOOKS LIKE WINDS SHOULD BE BELOW HIGH WIND CRITERIA BUT WILL 
NEED TO BE WATCHED AS WE GET CLOSER TO EVENT. THE DOWNSLOPE WARMING 
WILL BE SHORT LIVED AS NEXT COLD FRONT EXPECTED INTO NERN CO BY SAT 
AFTN WITH INCREASING MOISTURE AND UPSLOPE FLOW DEVELOPING SATURDAY 
NIGHT AND INTO SUNDAY AS FIRST PIECE OF ENERGY ROTATES THROUGH 
COLORADO.  

THERE ARE STILL SOME BIG DIFFERENCES BETWEEN THE MODELS IN HANDLING 
THE PIECES OF ENERGY AS THEY ROTATE THROUGH THE BROAD LARGE SCALE 
TROF DEVELOPING OVER THE NORTHERN PART OF THE COUNTRY. MAIN CHANGES 
WERE TO THE SAT NITE PERIOD AND ADDED SOME POPS FOR LOWER ELEVATIONS 
AS BOTH GFS/NAM SHOWING AIRMASS SATURATION BY 12Z SUNDAY. NO CHANGES 
BEYOND SUNDAY DUE TO UNCERTAINTIES.

&&

.AVIATION...SNOW CHANCES LOOK LOW THIS MORNING THRU THIS AFTN AT DIA 
WITH CEILINGS IN THE 5000-6000 FT RANGE.  WINDS TODAY WILL BECOME 
ELY BY AFTN WITH SPEEDS FROM 5-10 MPH.  TONIGHT SHOULD SEE LIGHT 
DRAINAGE WINDS DVLP WITH A GRADUAL DECREASE IN CLOUDS.     

&&

.BOU WATCHES/WARNINGS/ADVISORIES...NONE. 

$$

RPK/SWE