FXUS65 KBOU 042134
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
230 PM MST FRI DEC 04 2009

.SHORT TERM...TONIGHT...THE UPPER LEVEL RIDGE AXIS IS PROGGED TO 
SHIFT TO THE EAST AS THE NEXT STORM SYSTEM DROPS INTO THE NORTHERN 
ROCKIES.  SPATIAL CROSS-SECTIONS INDICATE A CONTINUATION OF GUSTY 
WINDS IN HIGHER MTNS AND FOOTHILLS.  NOT HIGHLIGHT MATERIAL BUT WL 
MNTN SOME GUSTS TO 60 MPH AND AREAS OF BLOWING SNOW.  AS FOR 
SATURDAY...THE TROF AXIS WL STRETCH FM NRN WY INTO NRN NV BY 00Z 
SUNDAY WITH A STG SWLY FLOW OVER NRN CO.  THE NEXT FRONT IS PROGGED 
TO MOVE INTO THE CWFA AROUND 18Z...WITH TEMPERATURES COOLING OFF THE 
REMAINDER OF THE AFTN.  GUIDANCE TEMPS FM THE NAM ON GIVE DENVER A 
HIGH OFF 22 FOR SATURDAY...WHILE THE GFS OUTPUT GIVES US 34.  WL CUT 
THE DIFFERENCE AND DROP THE HIGHS TO AROUND 30.  WL MNTN ISOLD SNOW 
SHOWERS IN ZONES 33 AND 35 DURING THE AFTN.  THERE WILL BE A STEADY 
LOWERING OF THE CLOUD BASE IN THE DENVER AREA BUT WL KEEP THE FCST 
DRY.  

.LONG TERM...MODELS STILL ON TRACK SHOWING A COLD FRONT PUSHING 
THROUGH THE AREA SATURDAY AFTERNOON WITH COLD AIR FLOWING INTO THE 
STATE BEHIND IT ON SATURDAY NIGHT AND SUNDAY. UPWARD VERTICAL 
VELOCITIES ASSOCIATED WITH A STRONG SHORT WAVE COMBINED WITH AN 
UPSLOPE LOW LEVEL FLOW WILL PRODUCE SNOW. LOOKS LIKE THE SNOW WILL 
BEGIN LATE SATURDAY NIGHT AND CONTINUE THROUGH MID TO LATE SUNDAY. 
ALL MODELS INDICATE PRECIPITATION AMOUNTS WILL BE ABOUT 0.20 TO 0.30 
INCHES OVER THE MOUNTAINS...FOOTHILLS AND URBAN CORRIDOR. WHICH IS 
NOT THAT IMPRESSIVE BUT SINCE THE SNOW TO LIQUID RATIO WILL BE 15-20 
TO 1...THIS CORRELATES TO 3 TO 6 INCHES. LESSER AMOUNTS ARE EXPECTED 
OVER THE EASTERN PLAINS. 

SNOW WILL END EVERYWHERE SUNDAY NIGHT AS WEAK RIDGING MOVES OVER 
COLORADO AS THE MAIN UPPER LEVEL TROUGH DROP INTO THE GREAT BASIN. 
AS THIS TROUGH PROGRESS EAST WE WILL SEE SNOW OVER THE MOUNTAINS 
BEGINNING MONDAY AND CONTINUING INTO TUESDAY. STILL UNCERTAIN IF AND 
HOW MUCH SNOW WILL FALL OVER THE URBAN CORRIDOR AND EASTERN PLAINS 
WITH THIS SYSTEM. MODELS STILL TRYING HONE IN ON A SOLUTION. RIGHT 
NOW IT MOVES ACROSS AS A STRONG OPEN TROUGH WHICH WOULD RESULT IN 
JUST LIGHT SNOW FOR THE LOWER ELEVATIONS. HOWEVER IF IT STRENGTHENS 
JUST A LITTLE MORE INTO A CLOSED LOW...HEAVIER SNOW AMOUNTS WILL BE 
POSSIBLE...ESPECIALLY OVER THE EASTERN PLAINS. TEMPERATURES WILL 
REMAIN COLD REGARDLESS OF WHICH MODELS IS CORRECT. 

WILL SEE DRYING AND SLIGHT WARMING BEHIND THE TROUGH ON WEDNESDAY. 
WEST TO NORTHWESTERLY FLOW ALOFT WILL PREVAIL BEHIND THE TROUGH FROM 
WEDNESDAY TO FRIDAY. WILL KEEP A CHANCE OF SNOW IN THE FORECAST FOR 
THE MOUNTAINS FOR OROGRAPHIC SNOW. RIGHT NOW IT APPEARS THE LOWER 
ELEVATIONS WILL STAY DRY. TEMPERATURES WARM A LITTLE EACH DAY BUT 
REMAIN BELOW NORMAL.

&&

.AVIATION...VFR CONDITIONS THRU SATURDAY.  WINDS WILL SHIFT BACK TO 
SSWLY THIS EVENING.  COULD SEE FROPA ASSOCIATED WITH THE NEXT SYSTEM 
BY 18Z SATURDAY...WITH A GRADUAL LOWERING OF THE CLOUD BASE THROUGH 
THE AFTN...BUT NO SHOWERS EXPECTED AT THIS TIME.    

&&

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

$$

COOPER/MEIER