635 FXUS63 KTOP 191737 AFDTOP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 1137 AM CST SAT JAN 19 2013 ...UPDATE TO AVIATION... .DISCUSSION... LATEST WATER VAPOR IMAGERY SHOWING A GRADUAL DEEPENING OF A LARGE SCALE TROUGH EXTENDING FROM NEAR HUDSON BAY SOUTHWESTWARD INTO THE NORTHERN PLAINS. THIS IS BEING AIDED BY THE CONTINUED AMPLIFICATION OF UPPER LEVEL RIDGING IN THE PACIFIC...JUST OFF THE WEST COAST WHICH IS DRIVING SHORTWAVE TROUGHS UP THROUGH THE GULF OF ALASKA AND INTO THE CANADIAN TROUGH. THE MOST RECENT SHORTWAVE TROUGH NOW MOVING SOUTHEAST ACROSS WY WILL PUSH A TROUGH OF LOW PRESSURE SOUTHEAST ACROSS THE COUNTY WARNING AREA TODAY WITH A WINDSHIFT TO THE NORTHWEST...BUT WARM AIR ALREADY OUT AHEAD OF THE SYSTEM WILL COMBINE WITH ABUNDANT SUNSHINE AND RELATIVELY MILD LOWS FOR MID JANUARY...TO PUSH HIGHS BACK INTO THE MIDDLE TO UPPER 50S...WITH NEAR 60 DEGREES EXPECTED SOUTH OF THE I 35 CORRIDOR. THIS WILL LIKELY BE THE WARMEST DAY IN GENERAL ACROSS THE CWA FOR THE WEEK. COOLER AIR WILL BEGIN TO WORK SOUTHWARD INTO THE CWA LATER TONIGHT AND SUNDAY. AFTER LOWS TONIGHT IN THE 20S...HIGHS SUNDAY WILL BE MORE SEASONABLE IN THE MID 30S NORTH TO LOWER 40S SOUTH. THE COLDEST SURGE OF CANADIAN AIR WILL ARRIVE SUNDAY NIGHT THEN LINGER THROUGH THE DAY MONDAY. AFTER LOWS MONDAY MORNING FROM NEAR 6 ABOVE ZERO IN THE FAR NORTHEAST CORNER NORTH OF HIAWATHA TO AROUND 13 IN THE SOUTHWEST AREAS OF THE CWA...WINDCHILLS WILL RANGE FROM NEAR 9 BELOW FAR NORTHEAST TO THE SINGLE DIGITS IN THE SOUTHWEST 1/3 OF THE CWA. HIGHS WILL RECOVER BACK INTO PRIMARILY THE 20S MONDAY WITH A FEW LOW 30S SOUTHWEST COUNTIES. AS THE CENTER OF THE COLD HIGH PRESSURE MOVES EAST OF THE CWA LATE MONDAY NIGHT...WINDS WILL REMAIN LIGHT...BUT BECOME SOUTHEASTERLY. AS A RESULT....TEMPS WILL NOT BE QUITE AS COLD MONDAY NIGHT WITH READINGS ABOUT 3 DEGREES WARMER THAN THE PREVIOUS NIGHT. AS THE LARGE SCALE TROUGH OVER THE EASTERN CONUS GRADUALLY SHIFTS OFFSHORE THROUGH MID WEEK...HEIGHT RISES AND LEESIDE TROUGHING IN THE HIGH PLAINS SHOULD RESULT IN A GRADUAL MODERATION IN TEMPS. HIGHS PRIMARILY IN THE 30S ON TUESDAY WILL WARM INTO THE 40S WEDNESDAY...THEN THE UPPER 40S TO LOWER 50S THURSDAY BEFORE ANOTHER SHORTWAVE TROUGH FROM THE PACIFIC RACES SOUTHEAST ACROSS THE PLAINS INTO FRIDAY RESULTING IN HIGHS GENERALLY IN THE 30S. AT THIS POINT...MOISTURE RETURN AHEAD OF THE END OF THE WEEK SYSTEM APPEARS TO BE DIRECTED GENERALLY SOUTHEAST OF THE CWA...SO WILL MAINTAIN A DRY FCST THROUGH THE WEEK. 63 && .AVIATION... VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. A SURFACE TROUGH IS PROGRESSING EASTWARD THROUGH THE AREA TODAY. THIS TROUGH WILL SHIFT THE WINDS TO THE NORTHWEST THIS AFTERNOON AS IT CONTINUES EASTWARD...WINDS GRADUALLY VEER TO THE EAST NORTHEAST TOWARD THE END OF THE PERIOD. SANDERS && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$