FXUS63 KTOP 041749 AAA
AFDTOP
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TOPEKA KS
1149 AM CST FRI DEC 4 2009
.UPDATE...
UPDATED FOR THE 18 UTC TAF ISSUANCE.
&&
.DISCUSSION...
SEE PREVIOUS DISCUSSION.
&&
.AVIATION...
WATER VAPOR SHOWING UPPER TROUGH AND ASSOCIATED THERMAL TROUGH SHIFTING
EAST OF THE CWA WITH GRADUAL WAA...SO DO NOT EXPECT MUCH MORE
THAN A FEW STRATOCU THIS AFTERNOON. WENT MOSTLY CLEAR THROUGH
TONIGHT WITH ONLY A FEW CIRRUS AFT 15Z SATURDAY. AS LEESIDE
TROUGHING INCREASES TONIGHT...WILL SEE THIS AFTERNOONS WEST WINDS
BECOME MORE SOUTHERLY AND SLOWLY INCREASE...MAINLY AFT 15Z
SATURDAY. INCREASED PREVAILING SOUTHERLY WINDS WITH SOME GUSTS
NEAR 20 KTS BY 18Z.
&&
PREV DISCUSSION...
A CLEAR AND CHILLY NIGHT ACROSS THE FA TONIGHT...WITH TEMPERATURES
IN THE LOW TEENS ACROSS MUCH OF THE AREA. LARGE LONGWAVE UPPER
TROF CONTINUES TO SLOWLY MOVE EASTWARD ACROSS THE CENTRAL US. NEXT
COUPLE OF WAVES PROGGED TO IMPACT OUR SENSIBLE WX SEEN ON WV
IMAGERY DROPPING INTO THE PAC NW AND ANOTHER SYSTEM DROPPING
SOUTHWARD INTO MANITOBA ATTM.
TODAY/SAT...FORECAST FOR FRIDAY AND SATURDAY BRING A SLIGHT
IMPROVEMENT AND A BRIEF REPRIEVE. LONGWAVE TROF PASSAGE TODAY
LEAVES AREA UNDER NORTHWESTERLY FLOW ALOFT BECOMING WESTERLY INTO
SATURDAY. THIS IN TURN SLOWLY REDEVELOPS THE LEE TROF AND BRINGS
SOUTHERLY FLOW AND WAA ACROSS THE AREA. TEMPS EXPECTED TO RISE
INTO THE MID 30S TODAY AND INTO THE 40S ON SATURDAY.
SUN/MON...SATURDAY NIGHT INTO SUNDAY MORNING THE AFOREMENTIONED
UPPER SYSTEMS SLIDE SLOWLY SOUTHWARD INTO THE NORTHERN
STATES...WITH WESTERN TROF MOVING INTO THE CTRL ROCKIES BY 12Z
SUNDAY. MEANWHILE SFC HIGH PRESSURE HAS SHIFTED SOUTHWARD INTO THE
CTRL PLAINS...WITH SFC AND 850MB FRONT BISECTING OUR CWA FROM NE
TO SW. AS A RESULT...TEMPERATURE PROFILES OVER THE NW COUNTIES
LOOK TO REMAIN BELOW FREEZING WHILE SE EXPERIENCE A PERIOD OF
TEMPS ABOVE FREEZING DURING THE DAY ON SUNDAY. ISENTROPIC LIFT ON
THE 285K SURFACE ALONG WITH FRONTOGENETICAL FORCING AND INCREASED
ASCENT FROM ENERGY EJECTING OUT OF THE WRN WAVE BRING A CHANCE FOR
PRECIPITATION TO THE AREA ON SUNDAY AND SUNDAY NIGHT. ENOUGH
UNCERTAINTY ABOUT UNSATURATED ICE GROWTH LAYER ACROSS THE SE
COUNTIES TO GIVE SE ZONES A DRIZZLE/FREEZING DRIZZLE PRECIP
TYPE...WHILE NW COUNTIES REMAIN ONLY SNOW CHANCES ATTM. SOME LIGHT
ACCUMULATIONS ARE POSSIBLE...WITH GENERALLY AN INCH OR LESS OF
SNOW POSSIBLE ALONG AND NORTH OF INTERSTATE 70. FREEZING DRIZZLE
POTENTIAL WILL BE MONITORED...HOWEVER AT THIS TIME ANY ACCUMULATION
APPEARS TO BE LIGHT. COLD AIR CONTINUES TO FILTER SOUTHWARD
THROUGH THE DAY ON MONDAY WITH HIGHS NOT EXPECTED TO BREAK OUT OF
THE 20S ACROSS NW COUNTIES AND LOW 30S EXPECTED SE.
DID NOT MAKE CHANGES BEYOND MONDAY. LATEST EC HAS COME MORE IN
LINE WITH EVENING GFS RUN AND BRING A SIGNIFICANT STORM INTO THE
CENTRAL PLAINS TUESDAY INTO TUESDAY NIGHT. ATMOSPHERE MAY BE
INITIALLY WARM ENOUGH FOR RAIN OR A MIX...FOLLOWED BY SNOW
WRAPPING AROUND BEHIND THE LOW. TRACK...TIMING AND VERTICAL
STRUCTURE STILL TOO FAR OUT TO CHANGE DETAILS IN CURRENT FORECAST
ATTM. 67
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
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