FXUS65 KBOU 070131 AAA
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
628 PM MST SUN DEC 6 2009

.UPDATE...SNOW HAS ACTUALLY REDEVELOPED EARLY THIS EVENING.  ONE 
BATCH OF LIGHT SNOW APPEARS TO BE ASSOCIATED WITH ENHANCED CLOUD 
FEATURE MOVING ACROSS THE NORTHERN FRONT RANGE...WHILE ANOTHER BATCH 
OF ENHANCED SNOWFALL IN THE DENVER METRO AREA WAS ASSOCIATED WITH 
WEAK LOW LEVEL CONVERGENCE ZONE.  HAVE INCREASED EVENING POPS DUE TO 
THE ABOVE MENTIONED FACTORS...BUT MOST ACCUMULATION THIS EVENING 
SHOULD BE LESS THAN AN INCH.  SATELLITE SHOWS UPPER LEVEL 
ENHANCEMENT TIMED TO MOVE NORTHEAST AWAY FROM THE FRONT RANGE BY 04Z 
SO ANY LIGHT SNOW SHOULD BE TAPERING OFF BY THEN.

.SHORT TERM...THE UPPER LEVEL SYSTEM THAT BROUGHT THE SNOW TODAY HAS 
MOVED OFF TO THE EAST. SOME FLURRIES AND LIGHT SNOW SHOWERS WILL 
LINGER THROUGH THE EVENING AND OVERNIGHT. MAY ALSO SEE SOME PATCHY 
FOG TONIGHT IF SKIES CLEAR. WESTERLY FLOW ALOFT WILL DEVELOP BEHIND 
THE TROUGH AND BACK TO THE SOUTHWEST MONDAY AS ANOTHER TROUGH DIGS 
SOUTH OVER THE WESTERN U.S. MOISTURE EMBEDDED IN THE WESTERLY FLOW 
WILL BRING SNOW TO THE MOUNTAINS MONDAY. THE WEST TO SOUTHWEST FLOW 
ALOFT ISN'T FAVORABLE FOR HEAVY OROGRAPHIC SNOW...BUT SHOULD STILL 
SHOULD SEE SOME PERIODS OF LIGHT SNOW...MAINLY WEST OF THE 
CONTINENTAL DIVIDE. IN ADDITION TO THE OROGRAPHIC LIFT...WARM AIR 
ADVECTION WILL PROVIDE SOME LIFT. MODELS SHOW SOME LIGHT QPF OVER 
THE PLAINS TONIGHT AND MONDAY. WILL KEEP SOME LOW POPS IN THE FOR 
THIS...BUT SINCE THERE WON'T BE ANYTHING ORGANIZED ANY ACCUMULATION 
WILL BE LIGHT.

.LONG TERM...NEXT STORM SYSTEM ORGANIZING OVER THE GREAT BASIN/ 
DESERT SOUTHWEST TRACKS EASTWARD ACROSS N-CNTRL/NERN COLORADO ON 
TUESDAY. UPR LOW OVER LAS VEGAS MONDAY NIGHT LIFTS NEWRD OVER SWRN 
NEB BY 00Z/WED AS PER THE NAM AND GFS. MODELS SHOW ACCOMPANYING 
SFC/850 LOW TRACKING ACROSS THE 4-CORNERS ERLY TUE MORNING THEN OUT 
ACROSS SERN COLORADO WHERE THE GFS INDICATES SOME INTENSIFICATION.  
DEEP LAYER MOISTURE AND MODERATELY STRONG QG ASCENT ON LEADING EDGE 
OF THIS SYSTEM REACHES THE THE N-CNTRL COLORADO MTNS EARLY ON 
TUE...THEN E-NEWRD OVER THE NERN PLAINS BY LATE MORNING OR ERLY 
AFTERNOON. SFC-700 FLOW EAST OF THE MTNS S-SELY MON NIGHT THEN 
E-SELY DURING THE DAY TUE THE SFC LOW NEAR LAMAR. BEST LIFT SOMETIME 
BETWEEN 12Z-18Z TUE...HOWEVER LOW LEVEL MOISTURE STILL LACKING 
DURING THE EARLY PART OF THE DAY...ESPLY UP ALONG THE FRONT RANGE 
AND OVER THE PALMER DIVIDE. COULD EVEN SEE A FEW BREAKS IN THE 
OVERCAST IN THE METRO AREA AROUND THIS TIME. THEN AS 850-600 FLOW 
SWINGS AROUND TO AN E-NELY COMPONENT BY MORNING/ERLY AFTERNOON ON 
TUE COULD SEE SEVERAL HRS OF LIGHT TO POSSIBLY MODERATE SNOWFALL ON 
THE PLAINS. NOW APPEARS THE I-25 URBAN CORRIDOR WILL ESCAPE WITH 
ONLY LIGHT ACCUMS...GENERALLY UNDER 3 INCHES...WHILE PLAINS AREAS 
OUT ACROSS THE NERN CORNER COULD SEE SNOW TOTALS APPROACHING ADVSY 
CRITERIA...AS WELL AS SOME BLOWING SNOW WITH THE TIGHT GRADIENT FLOW 
ON BACK SIDE OF EXITING 700-500MB CYCLONE. MODELS MOVE THIS SYSTEM 
MOVING OUT OF THE AREA TUE NIGHT WITH FLOW ALOFT RETURNING TO A NWLY 
COMPONENT. WHILE THE PLAINS DRY OUT LATE TUE NIGHT AND WED...MTN 
AREAS PARTICULARLY WEST/NORTHWEST FACING SLOPES SHOULD CONTINUE TO 
RECEIVE LIGHT POSSIBLY MODERATE SNOWFALL AT TIMES WITH CONTINUED 
OROGRAPHICS AND COLD ADVECTION. WEST SLOPES COULD PICK UP ANOTHER 
1-3 INCHES BY 00Z/THU. 

FOR THE REMAINDER OF THE EXTENDED PERIOD...BROAD UPPER TROUGH OVER 
THE CENTER OF THE LOWER 48 LIFTS AND MOVES EASTWARD ALLOWING FLOW 
OVER COLORADO TO RESUME A NEAR ZONAL FLOW COMPONENT. DRY W/SWLY  
DOWNSLOPE FLOW EAST OF THE MTNS ON THU WILL HELP TO WARM 
TEMPERATURES BUT NOT QUITE TO SEASONAL NORMS. ALSO SEE A DECREASE IN 
SNOWFALL ACTIVITY IN THE HIGH COUNTRY WITH MID-LEVEL SUBSIDENCE AND 
DRYING.            

BY THE END OF THE WEEK COULD SEE SNOW RETURNING TO THE HIGH COUNTRY  
WITH A WEAK SHORT WAVE TROUGH PASSING JUST TO OUR SOUTH. PLAINS 
APPEARS TO REMAIN DRY WITH TEMPERATURES RETURNING TO NEAR NORMAL 
READINGS BY THE WEEKEND. 

&&

.AVIATION...LOW CLOUDS AND OCCASIONAL LIGHT SNOW WILL LINGER OVER 
THE AREA THROUGH THE EVENING. BAND OF LOCALLY HEAVIER SNOWFALL WITH 
VISIBILITIES AS LOW AS 1 MILE AFFECTING KAPA RIGHT NOW...BUT THIS 
SHOULD ALSO DECREASE AS UPPER LEVEL SUPPORT AND CLOUD ENHANCEMENT 
FEATURE OVER THE NORTHERN FRONT RANGE MOVES OFF TO THE NORTHEAST BY 
04Z.  KDEN VISIBILITIES SHOULD REMAIN HIGHER AND CLOSER TO 5-6 MILES 
VSBY THIS EVENING WITH LOW LEVEL CONVERGENCE ZONE REMAINING FARTHER 
WEST.  CEILINGS WILL SLOWLY IMPROVE FROM AROUND 2000 FEET TO 
3000-4000 FEET LATE THIS EVENING. AFTER 06Z THERE MAY BE SOME 
CLEARING. IF IT DOES CLEAR FOG WILL BE GOOD POSSIBILITY. EXPECT MID 
AND HIGH CLOUDS TO INCREASE MONDAY AS MOISTURE ALOFT INCREASES. 
THERE IS A SLIGHT CHANCE FOR A SNOW SHOWER LATE TONIGHT AND MONDAY 
THAT MAY BRIEFLY PUSH CEILINGS BELOW 3000 FEET AND VISIBILITY BELOW 
3 MILES. 

&&

.BOU WATCHES/WARNINGS/ADVISORIES..NONE.

$$

BARJENBRUCH/MEIER/BAKER