FXUS63 KTOP 092259
AFDTOP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
459 PM CST WED DEC 9 2009
.UPDATE...
UPDATED THE AVIATION DISCUSSION FOR THE TAFS.
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.DISCUSSION...
SEE PREV DISCUSSION.
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.AVIATION...
VFR CONDITIONS WILL PREVAIL DUE TO A VERY DRY AIRMASS.
WOLTERS
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.PREV DISCUSSION.../336 PM CST WED DEC 9 2009/
TONIGHT AND THURSDAY...MAIN SHORT TERM FORECAST CHALLENGES HAVE TO
DO WITH TEMPERATURES. LOW PRESSURE SYSTEM THAT BROUGHT ALL THE SNOW
TO NORTHERN KANSAS WAS OVER LAKE HURON THIS AFTERNOON WITH A HIGH
PRESSURE RIDGE ACROSS THE WESTERN PLAINS. PRESSURE GRADIENT BETWEEN
THE TWO HAS WEAKENED AND WINDS WERE DECREASING AS A RESULT. AS THE
RIDGE AXIS MOVES EWD OVERNIGHT...EXTENSIVE DEEP SNOW COVER OVER
NORTHERN KANSAS SHOULD COMBINE WITH WEAKENING WINDS AND MOSTLY CLEAR
SKIES TO RESULT IN LOW TEMPERATURES SEVERAL DEGREES BELOW
STATISTICAL GUIDANCE FROM NAM AND GFS. SINCE SOME WIND STILL
EXPECTED TONIGHT...THIS COMBINED WITH COLD TEMPERATURES SHOULD LEAD
TO CHILL ADVISORY CRITERIA BEING MET APPROXIMATELY NORTH OF A
HERINGTON TO MANHATTAN TO HOLTON LINE.
TEMPERATURES ON THURSDAY ARE NOT EXPECTED TO RISE ANYWHERE NEAR AS
HIGH AS THE GFS MOS WOULD INDICATE...WHICH HAS HIGHS IN THE
30S...DESPITE OTHERWISE FAVORABLE WESTERLY WINDS. HAVE GONE CLOSER
TO THE COLDER NAM MOS FOR MAXIMA BUT UNDERCUT THAT A LITTLE TOO.
ONLY REAL CLOUDS COULD BE A BRIEF PERIOD OF CIRRUS TONIGHT
ASSOCIATED WITH VERY WEAK UPPER LEVEL DISTURBANCE. GDP
COLD ARCTIC AIR IS EXPECTED TO REMAIN IN PLACE WITH SOME MODERATION
THURSDAY NIGHT. WITH THE DEEP SNOW COVER AND LIGHT WINDS WILL SEE
TEMPERATURES FALL INTO THE SINGLE DIGITS AND TEENS ONCE AGAIN. THE
LOWEST TEMPERATURES WILL BE CONFINED TO THE AREAS WITH THE DEEPEST
SNOW PACK. ON FRIDAY NIGHT WILL SEE SOME WARM ADVECTION OCCUR ON THE
BACK SIDE OF THE ARCTIC HIGH THIS WILL MODERATE OVERNIGHT LOWS SOME
WITH TEENS OVER THE SNOW TO LOWER 20S IN THE EAST CENTRAL KANSAS.
NAM AND ECMWF SHOW SOME WARM ADVECTION AHEAD OF A MID LEVEL WAVE
MOVING THROUGH THE SOUTHERN STREAM OF THE SPLIT FLOW PATTERN
SATURDAY NIGHT INTO SUNDAY. COLUMN DOES NOT LOOK TO SATURATE VERY
DEEP AND DOES NOT SATURATE THE SNOW CRYSTAL GROWTH REGION AS WELL.
INTRODUCED SOME DRIZZLE IN THE AFTERNOON AND SOME FREEZING DRIZZLE
ACROSS THE NORTH. SOME FLURRIES OR SOME LIGHT SNOW IS POSSIBLE COME
SUNDAY EVENING AND LEFT IN THE SLIGHT CHANCE FOR NOW.
TEMPERATURES WILL WARM INTO THE UPPER 20S TO MID 30S ON SATURDAY AND
EVEN WARMER ON SUNDAY...THEN COOL BACK INTO THE 20S AND LOW 30S
MONDAY WITH A REINFORCING SHOT OF COLD AIR BEHIND A COLD FRONT. THE
COLD AIR SHIFTS TO THE EAST ON TUESDAY. DEEPENING UPPER TROUGH MOVES
THROUGH THE SOUTHERN STREAM TUESDAY THEN DAMPENS OUT OVER THE
SOUTHEAST U.S. AS IT MERGES WITH THE NORTHERN STREAM DEEP VORTEX
OVER EASTERN ONTARIO ON WEDNESDAY. THIS SYSTEM WILL STAY SOUTH OF
EASTERN KANSAS TO KEEP US DRY.
53
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.TOP WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY TIL 9AM THU FOR KSZ008>012-KSZ020>024-KSZ034>036.
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