005 
FXUS63 KTOP 221149 AAA
AFDTOP

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TOPEKA KS
549 AM CST SAT DEC 22 2012

...UPDATE TO AVIATION...

.DISCUSSION...

TODAY THROUGH SUNDAY...A LONGER WAVE LENGTH UPPER LEVEL TROUGH WAS 
LOCATED OFF THE PACIFIC NORTHWEST COASTLINE. AN INTENSE UPPER
LEVEL TROUGH OVER THE SOUTHERN GULF OF AK WILL DIG SOUTHEAST INTO
THE BASE OF THE LONGER WAVE LENGTH TROUGH OFF THE PACIFIC
NORTHWEST AND KICK OUT A WEAKER LEAD H5 SHORTWAVE TROUGH. THE
WEAKER H5 TROUGH WILL MOVE EASTWARD ACROSS THE PLAINS SATURDAY
NIGHT AND WILL ONLY PROVIDE THE AREA WITH SOME HIGH AND MID LEVEL
CLOUDS. LOW-LEVEL CAA ACROSS THE NORTHERN AND CENTRAL PLAINS LATE
SATURDAY AFTERNOON WILL BRING A COLD FRONT SOUTHWARD ACROSS THE CWA
SATURDAY NIGHT. SOUTHERLY WINDS WILL HELP TO WARM HIGHS TODAY INTO
THE MID TO UPPER 40S IN SNOW FREE AREAS...WITH MID TO UPPER 30S
ACROSS NORTHEAST KS WHERE THE SNOW COVER IS DEEPER. HIGHS ON
SUNDAY WILL BE MUCH COLDER ACROSS THE CWA BEHIND THE FRONT. THE
NORTHERN HALF OF THE CWA WILL STRUGGLE INTO THE LOWER TO MIDDLE
20S DUE TO SOME POST FRONTAL STRATUS...THE SOUTHERN COUNTIES MAY
REACH INTO THE MIDDLE 30S.

MONDAY THROUGH CHRISTMAS DAY (TUESDAY)...THE INTENSE H5 TROUGH
WITHIN THE BASE OF THE LONGER WAVE LENGTH TROUGH OFF THE PACIFIC
NORTHWEST COAST WILL DIG SOUTHEAST INTO NORTH CENTRAL TX EARLY ON
CHRISTMAS DAY...THEN LIFT NORTHEAST INTO SOUTHERN AR BY 00Z WED.
EXPECT DRY CONDITIONS ON MONDAY...WITH CONTINUED COLD
TEMPERATURES. HIGHS ON MONDAY WILL ONLY REACH THE LOWER 20S ACROSS
THE NORTHERN COUNTIES OF THE CWA WITH MID TO UPPER 20S ACROSS THE
REMAINDER OF THE CWA.

AS THE UPPER LEVEL TROUGH DIGS SOUTHEAST ACROSS THE SOUTHERN HIGH 
PLAINS MONDAY NIGHT THERE MAY BE ENOUGH LIFT FOR LIGHT SNOW TO 
DEVELOP ACROSS WESTERN KS WITH SOME MINOR SNOW ACCUMULATIONS POSSIBLE...BUT
THIS STEADY LIGHT SNOW SHOULD PASS WEST AND SOUTH OF THE CWA ON
CHRISTMAS DAY. THERE MAY BE SOME SCATTERED LIGHT SNOW SHOWERS OR
FLURRIES POSSIBLE ACROSS THE CWA ON CHRISTMAS DAY. AS THE SURFACE
AND 850MB LOW DEEPENS ACROSS EASTERN TX ON CHRISTMAS
DAY...NORTHEAST SURFACE WINDS WILL INCREASE TO 15 TO 25 MPH ACROSS
THE CWA. THE LOW-LEVEL CAA WILL ONLY ALLOW HIGHS TO REACH THE MID
TO UPPER TEENS ACROSS THE NORTHERN COUNTIES WITH MID TO UPPER 20S
ACROSS THE REMAINDER OF THE CWA. WIND CHILLS WILL BE IN THE SINGLE
DIGIT WITH SOME BELOW ZERO WIND CHILLS POSSIBLE ACROSS THE
NORTHERN COUNTIES OF THE CWA. LOWS TUESDAY NIGHT WILL BE IN THE
SINGLE DIGITS ACROSS MUCH OF THE CWA.

AS THE INTENSE UPPER LEVEL TROUGH ACROSS NORTHERN TX LIFTS NORTHEAST 
INTO SOUTHERN AR BY 00Z WED...IT LOOKS AS IF HEAVY SNOW WILL DEVELOP
ACROSS WESTERN AND NORTHERN AR...THEN SPREAD NORTHEAST ACROSS
SOUTHEAST MO...WESTERN KY...WESTERN TN...NORTHEAST INTO CENTRAL IN AND
OH BY TUESDAY NIGHT AND WEDNESDAY MORNING. ANYONE WITH TRAVEL PLANS
ACROSS THE MID AND LOWER MS RIVER VALLEY NORTHEAST INTO THE OH
RIVER VALLEY WILL NEED TO PAY ATTENTION TO THIS DEVELOPING WINTER
STORM. ON THE WARM SIDE OF THIS SYSTEM...SEVERE WEATHER WILL BE A
THREAT FROM THE NORTHEAST TX COAST ACROSS LA...MS AND INTO AL.

WEDNESDAY...WILL CONTINUE TO BE COLD. THE WINDS WILL DIMINISH AS A 
SURFACE RIDGE AXIS BUILDS SOUTHEAST ACROSS EASTERN KS. HIGHS WILL
ONLY REACH THE MID TEENS TO LOWER 20S.

THURSDAY THROUGH FRIDAY....ANOTHER H5 TROUGH WILL DIG SOUTHEAST 
ACROSS CA INTO THE FOUR CORNERS REGION. THEN LIFT OUT INTO THE 
PLAINS AS AN OPEN H5 WAVE. THE CWA MAY SEE SOME LIGHT SNOW DEVELOP
DURING THE DAY FRIDAY AS THE H5 TROUGH AXIS LIFTS NORTHEAST ACROSS
THE CENTRAL AND SOUTHERN PLAINS. THIS H5 TROUGH WILL AMPLIFY ONCE
IF MOVES EAST OF THE PLAINS INTO THE MID MS RIVER VALLEY. HIGHS
WILL SLOWLY MODERATE INTO THE MID TO UPPER 20S ON THURSDAY...WITH
LOWER TO MID 30S ON FRIDAY.

GARGAN


&&

.AVIATION...

VFR CONDITIONS WILL PERSIST AT ALL TERMINALS SITES THROUGH THE
FORECAST. LIGHT SOUTHEAST WINDS THROUGH 14Z WILL THEN BECOME
SOUTH TO SOUTHWEST...BUT AT SPEEDS UNDER 8 KTS...THEN VEER TO THE
WEST AND THEN NORTHWEST AFT 02Z WITH NEXT FROPA AS BKN CIRRUS
OVERSPREADS THE AREA AT 20 KFT. ANY POST FRONTAL MVFR STRATUS 
SHOULD STAY TO THE NORTH OF THE TERMINALS UNTIL AFT 12Z/23.

&&

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

$$