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. && $$