FXUS63 KTOP 221307
AFDTOP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
707 AM CST TUE DEC 22 2009
.UPDATE...
UPDATED FOR 12Z AVIATION.
&&
.DISCUSSION...
SEE PREVIOUS DISCUSSION.
&&
.AVIATION...
IFR TO NEAR IFR CEILINGS ARE EXPECTED THROUGH THE TAF FORECAST
PERIOD. A LARGE REGION OF LOW STRATUS CONTINUES TO EXPAND AND
SHOULD ENGULF TAF SITES BY MID/LATE MORNING. VISIBILITY WILL
REMAIN MVFR THROUGH THE PERIOD. PERIODS OF DRIZZLE CAN BE EXPECTED
BY LATE AFTERNOON INTO THE OVERNIGHT HOURS. CHANCES OF RAIN WILL BE
POSSIBLE BY THE END OF THE TAF PERIOD...ALTHOUGH DID NOT
DISTINGUISH FROM DZ GROUPING ATTM. BLAIR
&&
.PREV DISCUSSION... /ISSUED 411 AM CST TUE DEC 22 2009/
DISCUSSION...NO CHANGES MADE TO THE CURRENT WATCH AREA OR TIMING.
H5 RIDGING WAS MOVING INTO WESTERN KANSAS. CLOSED H5 LOW OVER THE
PACNW WILL BE THE ONE TO WATCH AS THIS IS WHERE THE MAIN WEATHER
MAKER THIS WEEK WILL COME FROM.
TODAY/TONIGHT...HIGH CLOUDS WERE COVERING MOST OF NORTHEAST KANSAS
THIS MORNING WITH A LOW STRATUS DECK MOVING SOUTH FROM NEBRASKA INTO
THE TOP CWA. PATCHY FOG/LOW STRATUS WAS ALREADY OVER CNK AND WILL
SPREAD SOUTH AND EAST THROUGH THE DAY SO WILL CONTINUE WITH PATCHY
FOG IN THE GRIDS. LLVL MOISTURE INCREASES THROUGH THE DAY AND AND
INTO TONIGHT WHILE BUFKIT SOUNDINGS SHOW SOME WEAK LIFT IN THE LOW
LEVELS AS WELL SO HAVE CONTINUED WITH DRIZZLE FOR TONIGHT.
WEDNESDAY/WED NIGHT...00Z MODELS HAVE HAD SOME CHANCE TO SAMPLE THE
STORM THAT IS APPROACHING AND THE TREND WITH THIS RUN HAS BEEN TO
MOVE THE TRACK OF THE SYSTEM SLIGHTLY FARTHER TO THE
NORTH/NORTHWEST. THAT SAID...A MAJORITY OF OUR CWA WILL REMAIN IN
THE WARM SECTOR FOR A LONGER PERIOD OF TIME THAN ORIGINALLY
THOUGHT. HAVE SLOWED THE CHANGEOVER TO SNOW JUST SLIGHTLY BECAUSE
CONFIDENCE STILL ISNT VERY HIGH WITH THE EVENTUAL TRACK SO HAVE
TRENDED TOWARD A SLOWER CHANGEOVER. ALSO HAVE STUCK WITH ALL RAIN
AS STRONG H85 WARM ADVECTION ON WED CREATES A BIG WARM LAYER WITH A
MAX TEMP OF AROUND 6-7C. WITH THAT MUCH WARMTH FEEL THAT FZRA WONT
BE MUCH OF AN ISSUE THROUGH THE DAY ON WED. THERE IS A TIME DURING
THE AFTERNOON ON WED WHEN THE WARM LAYER BEGINS TO COOL SOME AND
THERE COULD BE A BRIEF BOUT OF FZRA BUT FEEL IT WILL BE TOO BRIEF TO
MENTION IN THE GRIDS SO HAVE KEPT A STRAIGHT RAIN TO SNOW CHANGEOVER
STARTING ON WED NIGHT.
THURSDAY/THURS NIGHT...THE GFS/ECMWF/NAM/SREF ARE VERY SIMILAR AT
12Z THURS WITH THE PLACEMENT OF THE H5 LOW AND THE SECOND PIECE OF
ENERGY DROPPING IN FROM THE NORTHERN PLAINS. THE 00Z RUNS OF THE
AFOREMENTIONED MODELS DO NOT SHOW AS SHARP OF A NEGATIVE TILT AS THE
SYSTEM BEGINS TO LIFT E/NE ON THURS NIGHT. WHAT IS APPARENT IS THAT
THE SFC LOW DEEPENS AS IT MOVES ACROSS THE TOP CWA. THE HEIGHT OF
THE STORM WILL BE THROUGH THE DAY ON THURSDAY AS RAIN CHANGES TO
SNOW, THE WIND PICKS UP WITH GUSTS TO 45 MPH NEAR CONCORDIA AND
POINTS NORTH AND WEST. IT STILL LOOKS LIKE THE AXIS OF HEAVIEST
SNOW WILL BE IN THE MARYSVILLE TO CLAY CENTER TO MINNEAPOLIS
CORRIDOR WITH UPWARDS OF 10 INCHES POSSIBLE. AMOUNTS WILL QUICKLY
TAPER OFF AS YOU MOVE EAST WITH THE TOPEKA AREA AROUND 5 INCHES AND
AROUND 3-4 IN LAWRENCE WHEN ALL IS SAID AND DONE. AS THE LOW
CONTINUES TO MOVE NORTH AND EAST, COLD AIR PLUNGES IN BEHIND AND
WILL DROP TEMPS INTO THE TEENS ON THURS NIGHT. WITH A NORTH WIND
GUSTING INTO THE 40S TRAVEL ALONG EAST-WEST ORIENTED ROADS WILL BE
ESPECIALLY TREACHEROUS.
FRIDAY/SATURDAY...SNOW WINDS DOWN ON FRIDAY WITH LITTLE ADDITIONAL
ACCUMULATIONS EXPECTED. NO ADDITIONAL CHANGES MADE TO THE WEEKEND
FORECAST.
SALLY
&&
.TOP WATCHES/WARNINGS/ADVISORIES...WINTER STORM WATCH FROM 6 PM WEDNESDAY TO NOON FRIDAY FOR KSZ008-
KSZ009-KSZ010-KSZ011-KSZ012-KSZ020-KSZ021-KSZ022-KSZ023-KSZ024-
KSZ034-KSZ035-KSZ036-KSZ037.
&&
$$
