FXUS63 KTOP 051131
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
531 AM CST SAT DEC 5 2009

.UPDATE...

UPDATED TO INCLUDE THE 12Z AVIATION DISCUSSION.

&&

.AVIATION...

FOR THE 12Z TAFS...VFR CONDITIONS EXPECTED THROUGH THE PERIOD.
SOUTHERLY WINDS..GUSTY AT TIMES THIS AFTERNOON WITH DECENT
MIXING...WILL PREVAIL. CLOUDS AOA 15KFT WILL MOVE IN AHEAD OF THE
NEXT WEATHER SYSTEM AFTER 00Z SUNDAY.

LUNDE

&&

.PREV DISCUSSION... /ISSUED 338 AM CST SAT DEC 5 2009/ 

DISCUSSION...

..LIGHT SNOW ACCUMULATION POSSIBLE SUNDAY...WITH STRONG WINTER
STORM STILL POSSIBLE TUESDAY AND TUESDAY NIGHT...

TEMPS WARMER THAN PREVIOUS NIGHTS TONIGHT AS BETTER MIXING AND
WAA HAVE MOVED IN OVER THE AREA. TEMPS IN THE 20S WITH MOSTLY
CLEAR SKIES ATTM. WEAK UPPER RIDGE MOVING IN FROM THE WEST...AHEAD
OF LARGER LONGWAVE TROF SLIDING INTO THE NORTHERN ROCKIES AND PAC
NW.

FOR TODAY...EXPECTING A DECENT WARMUP INTO THE 40S ACROSS THE
AREA AS MID LEVEL TEMPS RISE 6-8C FROM YESTERDAY. SHOULD BE ABLE
TO REALIZE A MIX TO ABOUT 900MB WITH THOSE TEMPS AS A RESULT.

TONIGHT/SUN/MON...INVERTED SFC TROF AND MID LEVEL FRONT SLIDES
INTO THE NORTHERN COUNTIES TONIGHT INTO SUNDAY MORNING. THINK
ISENTROPIC LIFT AND FRONTOGENESIS WILL INITIALLY WORK TO
SATURATING THE CLOUD LAYER BUT EXPECT TO BEGIN GENERATING PRECIP
BY MID MORNING SUNDAY ACROSS THE NC COUNTIES. SHORTWAVE TROF THEN
EJECTS OVER THE BOUNDARY SUNDAY INTO SUNDAY NIGHT AND USHERS IN
COLD AIR MASS BEHIND. COULD SEE AN INCH TO AN INCH AND A HALF
ACROSS NC KS BY SUNDAY NIGHT WITH DIMINISHING AMTS SE. DONT EXPECT
TEMPS TO GET OUT OF THE MID 20S ACROSS THE NC COUNTIES ON
MONDAY...WITH LOW TO MID 30S SOUTHEAST.

MONDAY NIGHT AND TUESDAY...POTENTIAL STRONG SYSTEM MOVING INTO
THE CTRL PLAINS MONDAY NIGHT THROUGH TUESDAY STILL THE BIG CONCERN
THIS FORECAST PACKAGE. MODELS DEPICT A PROLONGED PERIOD OF
ISENTROPIC LIFT ACROSS THE NORTHERN COUNTIES AS THE SYSTEM
APPROACHES MONDAY NIGHT INTO TUESDAY MORNING...WHICH GIVEN CURRENT
QPF COULD BRING INITIAL SNOWFALL OF A FEW INCHES OR MORE TO NORTH
CENTRAL KANSAS BEFORE THE SFC LOW EVEN GETS OUT OF THE HIGH
PLAINS. IMPRESSIVE ISENTROPICS CONTINUE AS 850MB FLOW ON THE GFS
BY 18Z TUESDAY IS SOUTH AT 50KTS...WITH THE 0C 850MB LINE JUST
SOUTH OF INTERSTATE 70. MID LEVEL DEFORMATION ZONE AND ENERGY FROM
UPPER TROF INTERACT WITH FRONTOGENETICAL FORCING BAND IN THE
COLDER AIR THROUGH THE AFTERNOON HOURS TUESDAY...BRINGING
CONTINUED POTENTIAL FOR SIGNIFICANT SNOW ESPECIALLY NORTH OF I70.
FORECAST FOR SOUTHERN COUNTIES IS TRICKIER...AS 0Z EC HAS COME
SLIGHTLY MORE NORTH BRINGING WARMER TEMPS INTO OUR SOUTHERN
COUNTIES LIKE THE GFS. /WILL ALSO HAVE TO WATCH MODELS AS THE RUNS
UNFOLD FOR ANY INTRUSION OF MID LEVEL DRY AIR OVER EASTERN
COUNTIES...WHICH COULD LEAD TO MIXED PRECIP THERE./ CURRENTLY HAVE
KEPT HIGHER SNOW AMOUNTS NORTH OF THE INTERSTATE WITH DIMINISHING
AMOUNTS SOUTHWARD. ALSO OF NOTE IS THE POTENTIAL FOR BREEZY
CONDITIONS BEHIND THE SYSTEM TUESDAY NIGHT AND COULD BRING BLOWING
AND DRIFTING OF ANY PREVIOUS DAY SNOWFALL. AS ALWAYS...SHIFTS IN
THE TRACK OF THE STORM WILL HAVE CONSIDERABLE IMPACT ON THE
FORECAST. STAY TUNED FOR UPDATES AS THE SYSTEM DEVELOPS. 67

&&

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

&&

$$