FXUS63 KTOP 022320
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
520 PM CST WED DEC 2 2009

.UPDATE...UPDATED FOR 00Z AVIATION.

&&

.AVIATION...VFR THROUGH THE TAF PD. GUSTY WIND WILL DIMINISH OVER
THE NEXT SEVERAL HOURS. SUSTAINED WIND WILL STAY AROUND 10 KTS SO
FOG IS NOT AN ISSUE TONIGHT. A FEW CLOUDS ON THURSDAY AFTERNOON
COULD PRODUCE SOME FLURRIES BUT RESTRICTIONS TO VISIBILITY ARE NOT
EXPECTED.

SALLY
&&

.PREV DISCUSSION... /ISSUED 234 PM CST WED DEC 2 2009/ 

DISCUSSION...
FOCUS IS ON TEMPS AND CLOUDS TONIGHT-THU. 18Z SFC MAP FEATURED A SFC 
LOW ACROSS TN WITH A MODIFIED POLAR AIRMASS SURGING SOUTH THROUGH 
THE PLAINS. VIS SAT LOOP SHOWS SCT STRATUS DEVELOPMENT ACROSS NE/SD. 
STEEPENING LAPSE RATES HAVE ALSO ALLOWED FOR GUSTY WINDS TO APPROACH 
40 MPH AT MIDDAY. FEEL THE GUSTY WINDS WILL PERSIST INTO THE 
NIGHTTIME HOURS GIVEN CONTINUED CAA/STEEP LAPSE RATES TONIGHT BEFORE 
DIMINISHING AFTER MIDNIGHT. THE WINDS MAY ACT TO HOLD TEMPS UP 
SOMEWHAT HOWEVER GIVEN THE COMBO OF CAA AND PTCLDY SKIES EXPECT LOWS 
TO FALL INTO THE LOWER RANGE OF MOS GUIDANCE WHICH OUR CURRENT FCST 
REFLECTS. ON THU...LOOK FOR CONTINUED CAA WITH SOME SCT STRATUS 
DEVELOPMENT IN THE SNOW GROWTH LAYER BY MIDDAY. THIS COULD LEAD TO 
SCT SNOW FLURRIES SO I WILL LEAVE THE CURRENT FCST AS IS WITH 
FLURRIES MENTIONED ACROSS THE NORTHERN THIRD OF THE CWA. MAX TEMPS 
SHOULD REMAIN BELOW AVG IN THE 30S OR CLOSER TO THE METMOS GUIDANCE.

CO

FRIDAY AND SATURDAY ARE EXPECTED TO BE QUIET AS A COLD AND DRY 
AIRMASS SLIDES TO THE SOUTH WITH THE UPPER TROUGH SWINGING TO THE 
EAST. WITH DEWPOINTS UPSTREAM IN THE SINGLE DIGITS...SOME VERY DRY 
AIR SHOULD MOVE IN AND LOWS FRIDAY MORNING IN THE TEENS LOOK 
REASONABLE WITH SOME CLEARING SKIES. 

HAVE MAINTAINED SOME SLIGHT CHANCE POPS FOR LIGHT SNOW SUNDAY AND 
SUNDAY NIGHT. THE MODEL CONSENSUS IS FOR A WEAKENING WAVE TO MOVE 
ACROSS THE AREA WITHIN WESTERLY FLOW ALOFT. TEMPS SUNDAY AFTERNOON 
AND SUNDAY NIGHT LOOK TO BE COLD ENOUGH FOR ALL SNOW. GIVEN A SMALL 
WINDOW FOR FORCING AND LIMITED MOISTURE...ANY ACCUMULATIONS APPEAR 
TO BE LIGHT. AFTER A BREAK ON MONDAY DUE TO SHORTWAVE RIDGING... 
ANOTHER WAVE MAY POSSIBLY MOVE ACROSS THE CENTRAL PLAINS MAINLY ON 
TUESDAY. THERE IS STILL SOME UNCERTAINTY WITH THIS SYSTEM AS THE GFS 
IS MUCH MORE AMPLIFIED THAN THE ECMWF. CONSIDERED INCREASING POPS 
FOR TUESDAY AS THERE APPEARS TO BE SOME AGREEMENT ON A SECOND WAVE 
AFFECTING THE AREA. HOWEVER THE GFS ENSEMBLE WAS SLIGHTLY SLOWER 
THAN THE OPERATIONAL RUN. THEREFORE WITH THE UNCERTAINTY IN TIMING 
AND STRENGTH OF THE WAVE...HAVE KEPT POPS AT A SLIGHT CHANCE. BOTH 
THE GFS AND ECMWF APPEAR TO BE MUCH COOLER THAN THE PREVIOUS 
FORECAST AND HAVE TRENDED IN THIS DIRECTION. BECAUSE OF THIS HAVE 
KEPT A SLIGHT CHANCE FOR SNOW ACROSS MOST OF THE FORECAST AREA FOR 
TUESDAY.

WOLTERS

&&

.TOP WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$