FXUS63 KTOP 100922
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
322 AM CST THU DEC 10 2009

.DISCUSSION...

MAIN FORECAST PROBLEMS FOR THIS CYCLE ARE TEMPERATURES INTO THE 
WEEKEND AND PRECIPITATION CHANCES THIS WEEKEND.

0Z UPPER AIR DATA SHOWING LONGWAVE TROF STILL ENTRENCHED OVER THE 
NORTHERN AND CENTRAL CONUS. A WEAK SHORTWAVE WAS ROTATING SOUTHEAST 
FROM THE NORTHERN ROCKIES WITH SOME ASSOCIATED HIGH CLOUDS EXITING 
THE AREA EARLY THIS MORNING. WATER VAPOR IMAGERY SUGGESTS OTHER 
SHORTWAVE TROFS AROUND 35N/140W AND 40N/160W. SURFACE HIGH PRESSURE 
WAVE OVER CENTRAL OKLAHOMA AT 08Z WITH LIGHT WEST WINDS LOCALLY. 
TEMPERATURES HAVE BOUNCED AROUND OVER THE PAST SEVERAL HOURS WITH 
925MB WINDS OF 20-25KT PROVIDING SOME MIXING...WITH RESULTING WIND 
CHILLS IN THE -20 TO 0 RANGE FOR THE MOST PART. 

AFTER A VERY COLD NIGHT TONIGHT...TREND FOR THE NEXT FEW DAYS WILL 
BE A WARMING ONE. UPPER HEIGHTS RISE CONSISTENTLY WITH STEADY LOW 
LEVEL WARM AIR ADVECTION AS SURFACE WINDS BECOME MORE SOUTHERLY WITH 
THE SLOW EXIT OF THE SURFACE RIDGE AND LEE TROFFING FROM FAST ZONAL 
FLOW. 

EXPECT A SLOW INCREASE IN WINDS THIS MORNING TO COMBINE WITH 
THE COLD TEMPS TO KEEP WIND CHILL VALUES INTO ADVISORY LEVELS FOR AT 
LEAST A FEW HOURS...AND GOING ADVISORY SEEMS TO HANDLE THE SITUATION 
WELL. NEARLY FULL SUNSHINE WILL BE COUNTERACTED BY DEEP AND STILL 
RATHER FRESH SNOWFALL TO KEEP TEMPS BELOW MOS NUMBERS. SHOULD SEE 
SOME CIRRUS TONIGHT WHILE A WEAK LOW LEVEL RIDGE MOVES THROUGH. WILL 
KEEP TEMPS BELOW MOS AGAIN...BUT APPEARS WIND CHILL VALUES WILL 
REMAIN ABOVE ADVISORY RANGE. SOUTHERLY WINDS DEVELOPING ON FRIDAY 
WILL BRING MOST LOW LEVEL PARCELS OFF OF SNOW FREE AREAS...BUT SNOW 
WILL REMAIN IN PLACE. TRENDED CLOSER TO MOS NUMBERS HERE. 

DEEPER WARM AIR ADVECTION WILL BEGIN TO BRING IN BETTER MOISTURE  
FRIDAY NIGHT INTO SATURDAY NIGHT. MODELS STRUGGLE WITH THE TIMING OF 
THE AFOREMENTIONED SHORTWAVES...AND THUS WITH THE DEPTH OF THE LIFT 
AND MOISTURE. MODEL SOUNDINGS ARE SIMILAR WITH QUITE SATURATED LOW 
LAYERS AND DEWPOINTS RISING INTO THE 30S BY SATURDAY AFTERNOON. WITH 
QUESTIONS REMAINING IN THE MID AND UPPER LEVELS...WITH INTRODUCE 
ONLY DRIZZLE FOR SATURDAY AND SATURDAY NIGHT. COULD ALSO SEE SOME 
FOG OVER THE SNOW IF THE DEWPOINT PROGS VERIFY. WILL LEAVE 
PRECIPITATION PLACEMENT UNTOUCHED FOR SUNDAY WITH UNCERTAINTY HIGH. 

65

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL DUE TO A VERY DRY AIRMASS.

WOLTERS

&&

.TOP WATCHES/WARNINGS/ADVISORIES...WIND CHILL ADVISORY UNTIL 9 AM 
THURSDAY FOR KSZ008-KSZ009-KSZ010-KSZ011-KSZ012-KSZ020-KSZ021-KSZ022-
KSZ023-KSZ024-KSZ034-KSZ035-KSZ036.

&&

$$