FXUS65 KBOU 021119
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
410 AM MST WED DEC 02 2009

.SHORT TERM...MAIN BAND OF SNOWFALL HAS MOVED OVER THE FORECAST AREA 
DURING THE EARLY MORNING HOURS...PRODUCING 2-3 INCH SNOWFALLS UP AND 
DOWN THE URBAN CORRIDOR.  THIS BAND IS NOW OVER DOUGLAS COUNTY AND 
THE PALMER DIVIDE...WHILE PERSISTENT LIGHTER SNOWFALL CONTINUES 
FALLING ALL THE WAY UP TO THE WYOMING BORDER.  IN THE PAST 20 
MINUTES IT APPEARS THAT A BACK EDGE TO THE SNOW IS SHOWING UP ON THE 
KCYS WSR-88D.  WIND PROFILERS ARE SHOWING NICE UNIDIRECTIONAL SHEAR 
PROFILE ABOVE THE LOW LEVEL UPSLOPE WINDS AND THIS EXPLAINS THE 
PERSISTENT NATURE OF THE BANDED PRECIPITATION.  MODELS SHOW THAT 
THIS WIND PROFILE WILL REMAIN INTACT MOST OF THE DAY...MAKING IT 
POSSIBLE FOR THE BANDED SNOW FLURRIES TO LAST INTO THE AFTERNOON.  
TEMPERATURES HAVE FALLEN INTO THE UPPER TEENS WITH COLDER AND DRIER 
AIR EXPECTED TO CONTINUE MOVING OUT OF WYOMING AND INTO NORTHEAST 
COLORADO ALL DAY.  HIGH TEMPERATURES MAY STRUGGLE TO GET BACK TO THE 
20 DEGREE MARK.  ALTHOUGH SNOW FLURRY ACTIVITY MAY CONTINUE MOST OF 
THE DAY...THE COLD AIR AND LIMITED MOISTURE AVAILABILITY WILL KEEP 
ACCUMULATION RATES LOW.  DO NOT EXPECT ANY MORE THAN ONE INCH OF 
ADDITIONAL SNOWFALL.  THE GFS AND NAM INDICATE ADDITIONAL QPF 
OVERNIGHT AS THE CYCLONIC CURVATURE OF THE UPPER TROUGH REMAINS OVER 
THE REGION.  ANOTHER NIGHT OF LIGHT SNOW WILL RESULT...BUT 
ACCUMULATIONS SHOULD BE ONE INCH OR LESS.  

.LONG TERM...AN UPPER LEVEL TROUGH WILL REMAIN OVER THE AREA ON THU 
WITH NNW FLOW ALOFT.  MEANWHILE ANOTHER SURGE OF COLDER AIR WILL 
MOVE INTO NRN CO WITH WEAK UPSLOPE FLOW AS SOME QG ASCENT MOVES 
SOUTHWARD ACROSS THE AREA THRU THE MID MORNING HOURS.  QG VERTICAL 
VELOCITES ARE MAINLY WEAK HOWEVER LAPSE RATES ARE PRETTY DECENT. 
MOISTURE PROFILE IS MORE FAVORABLE FOR SOME LIGHT UPSLOPE SNOW IN 
AND NR THE FOOTHILLS BASED ON THE NAM VS THE GFS.  AT THIS TIME WILL 
KEEPS POPS IN THE CHC CATEGORY.  IN THE MTNS OROGRAPHICS WILL REMAIN 
WEAK SO WILL ONLY MENTION SCT -SHSN.  TEMPERATURES ON THU WILL BE 
VERY COLD WITH READINGS ONLY REACHING THE UPPER TEENS TO LOWERS 20S 
OVER NERN CO.  BY FRI THE UPPER LEVEL TROUGH WILL MOVE EAST OF THE 
AREA WITH GENERALLY DRY NW FLOW ALOFT SO WILL NOT MENTION ANY PCPN.  
LOW LEVEL FLOW WILL WILL BECOME MORE DOWNSLOPE BY FRI AFTN AS LEE 
TROUGH BEGINS TO DVLP NR THE FOOTHILLS.  THIS SHOULD ALLOW FOR SOME 
MODERATION IN TEMPS WITH READINGS RISING INTO THE UPPER 20S TO LOWER 
30S OVER NERN CO.  

FOR FRI NIGHT INTO SAT THE FLOW ALOFT WILL INCREASE AND BECOME MORE 
WNW AS AN UPPER LEVEL TROUGH DVLPS OVER THE NRN ROCKIES.  
CROSS-SECTIONS SHOW LIMITED MOISTURE OVER THE AREA SO WILL ONLY 
MENTION A SLIGHT CHC OF -SHSN IN THE MTNS.  WINDS WILL INCREASE IN 
THE MTNS AND FOOTHILLS FRI NIGHT INTO SAT BUT SPEEDS SHOULD STAY BLO 
WARNING CRITERIA.  TEMPERATURES SHOULD CONTINUE TO MODERATE ON SAT 
WITH HIGHS RISING BACK INTO THE 30S ACROSS NERN CO.  FOR SUN INTO 
MON THERE IS STILL SOME DISAGREEMENT BETWEEN THE LONGER RANGE MODELS 
ON HOW THE NEXT UPPER LEVEL TROUGH WILL DVLP.  RIGHT NOW IT APPEARS 
THE TROUGH WILL BECOME ELONGATED FROM THE NRN ROCKIES WESTWARD TO 
THE WEST COAST.  AS A RESULT THIS WILL LEAVE LEAVE NRN CO IN MAINLY 
ZONAL FLOW ALOFT.  MEANWHILE IT DOES APPEAR ANOTHER SHOT OF COLDER 
AIR WILL MOVE SOUTH INTO NRN CO SAT NIGHT INTO SUN WITH UPSLOPE FLOW 
DEVELOPING.  WITH POSITION OF UPPER LEVEL JET COULD SEE SOME 
ENHANCEMENT OF PCPN IF ENOUGH MOISTURE IS AVAILABLE FM SUN INTO 
MON.                                   

&&

.AVIATION...SNOW FLURRY ACTIVITY IS EXPECTED TO CONTINUE THROUGH AT 
LEAST THE MORNING HOURS.  CIGS AND VSBYS WILL FLUCTUATE IN AND OUT 
OF IFR CONDS THROUGH THE DAY.  ADDITIONAL FLURRIES WILL BE POSSIBLE 
THROUGH THE AFTERNOON.  ANOTHER ROUND OF LIGHT SNOW IS EXPECTED 
OVERNIGHT AS THE COLD AIR AND LIGHT UPSLOPE FLOW CONTINUES.  
ACCUMULATIONS WILL BE LIGHT.  CIGS AND VSBYS IN IFR CATEGORY MAY 
OCCUR AGAIN TONIGHT. 

&&

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

$$

KDRBY/RPK