FXUS63 KTOP 290540
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1140 PM CST SAT NOV 28 2009

.UPDATE...

UPDATED FOR 06 UTC AVIATION.

&&

.DISCUSSION...

SEE PREVIOUS DISCUSSION.

&&

.AVIATION...

FRONTAL BOUNDARY NEAR STJ TO TOP TO HUT LINE AT 05Z SUN. EXPECTING
NORTH WINDS AT TOP AND FOE AT THE BEGINNING OF THE TAF PERIOD.
FORECAST SOUNDINGS AND LOW LEVEL LAYER RH PROGS SHOW MOISTENING OF
LOW LAYERS OVERNIGHT WITH A PERIOD OF MVFR CIGS EXPECTED TO FORM
THEN GRADUALLY DECREASE BY LATE MORNING SUNDAY AS DRIER AIR MOVES
IN. VFR CIGS EXPECTED AFTER MID DAY SUNDAY. SCATTERED VFR CLOUDS
EXPECTED AFTER 22Z. NORTH WINDS AROUND 14 KTS EXPECTED FORM MUCH
OF THE DAY BEFORE BECOMING LIGHT WITH SFC HIGH BUILDING IN.

53

&&

.PREV DISCUSSION... /ISSUED 255 PM CST SAT NOV 28 2009/

DISCUSSION...

GOING FORECAST APPEARS TO HAVE THINGS WELL IN HAND FOR TONIGHT AND 
SUNDAY. FRONTAL BOUNDARY ENTERING FAR NWRN CWA AT MID AFTERNOON
AND MOVING SLOWLY SEWD. AT THIS TIME...ONLY CLOUDS ASSOCIATED WITH
SYSTEM ARE EXTENSIVE CIRRUS ACROSS NEBRASKA AND WRN KS. AS FRONT
CONTINUES SEWD OVERNIGHT...NAM AND GFS FORECAST LIFT UP AND OVER
FRONT TO PRODUCE EXTENSIVE DECK OF STRATUS...WITH A LITTLE DRIZZLE
POSSIBLE IN EC KS AND AREAS SWD. FRONT EXITS EC KS NEAR SUNRISE
SUNDAY AND DECK OF STRATUS SHOULD THIN AND BREAK UP SOME DURING
THE AFTERNOON AS DRIER LOW-LEVEL AIR IS ADVECTED IN ON STRONG NLY
WINDS. HIGHS TODAY NORTH OF FRONT IN NEBRASKA MOSTLY IN THE MID TO
UPPER 40S...AND EXPECT SIMILAR HIGHS FOR MUCH OF ERN AND NRN KS ON
SUNDAY.

BASE OF THE UPPER TROF SLIDES OVER THE FA SUNDAY NIGHT INTO MONDAY
MORNING. MAY KEEP A LIGHT WEST WIND OVERNIGHT BUT STILL EXPECT
DECOUPLED AREAS TO FALL INTO THE MID 20S. WAA ALOFT CONTINUES ON
MONDAY AS 850MB TEMPS RISE TO 2-4C AND SURFACE FLOW SHIFTS
SOUTHWESTERLY. SPEEDS LIKELY LIMITED BY SHORTWAVE RIDGE AHEAD OF
UPPER LOW OVER AZ AIDING IN WEAKENING SFC PRESSURE GRADIENT. HAVE
HIGHS ON TUESDAY A FEW DEGREES WARMER STILL...AS STILL SEE ENOUGH
WARMING ALOFT DESPITE LOWER MIXING TO BRING HIGHS INTO THE MID TO
UPPER 50S.

SOME SLIGHT TIMING DIFFERENCES BUT GENERAL TREND IS TO BRING NEXT
FRONT INTO THE CWA TUESDAY NIGHT IN TO WEDNESDAY MORNING. WILL
LIKELY SEE FALLING TEMPERATURES ON WEDNESDAY AS BRISK NORTH WINDS
AND CAA CONTINUE THROUGH THE DAYLIGHT HOURS.  

GUIDANCE DIVERGES CONSIDERABLY BEYOND WEDNESDAY. LATEST EC AND GFS
BOTH HAVE BROAD TROF ACROSS THE OHIO VALLEY WITH NEXT WAVE MOVING
INTO THE PAC NW. TIMING ON THIS WAVE IS CONSIDERABLY
DIFFERENT...SUCH THAT THE GFS DROPS THE SYSTEM INTO SOUTHERN CALI
AND ELONGATES THE WAVE ACROSS THE US...WHILE THE EC IS SLOWER WITH
THE INCOMING SYSTEM AND THUS MORE PROGRESSIVE WITH THE EASTERN
TROF. BOTH SUGGEST COOLER TEMPERATURES FOR THURSDAY...WITH LATEST
EC THEN KEEPING COLDER NW FLOW ON FRIDAY WHILE GFS DEPICTS A MID
LEVEL RIDGE AND A WARMUP. PREVIOUS TREND WAS TOWARD A COOLER
SOLUTION AND KEPT GRIDS COOLER. KEPT GUIDANCE GRIDS FOR SATURDAY
ATTM. 67

&&

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

&&

$$