FXUS63 KTOP 082355
AFDTOP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
555 PM CST TUE DEC 8 2009
.UPDATE...
UPDATED THE AVIATION DISCUSSION FOR THE 00Z TAFS.
&&
.DISCUSSION...
21Z RUC AND 18Z NAM SHOW FORCING FOR SNOW TO BE RATHER PROGRESSIVE
THROUGH THE EVENING AS CYCLOGENESIS INCREASES OVER THE MIDDLE MS
RIVER VALLEY. WITH THE MID LEVEL ENERGY IN THE FORM OF AN OPEN
WAVE...THIS MAKES SENSE THAT THE SFC LOW WOULD DEEPEN TO THE EAST OF
THE AREA. CROSS SECTIONS SHOW THE AREA OF MID LEVEL FRONTOGENESIS
LIFTING EAST AND NORTHEAST BY 06Z AND DRY AIR ADVECTION BEHIND THE
WAVE WILL DRY OUT MID LEVELS QUICKLY AFTER 06Z. IN GENERAL EXPECT
ONE MORE ROUND OF MODERATE TO HEAVY SNOW BETWEEN NOW AND ABOUT 10
PM. WINDS WILL INCREASE DRAMATICALLY WITH THE LOW DEEPENING TO THE
EAST. AS LONG AS THERE IS SOME LIGHT SNOW FALLING...BLOWING SNOW
WITH VSBY BETWEEN 1/2SM AND ZERO IS A POSSIBILITY AND WILL NEED TO
MONITOR THE BLIZZARD WARNING. THE BLOWING SNOW TENDS TO DECREASE
PRETTY QUICKLY ONCE SNOWFALL HAS ENDED EVEN WITH SNOW ON THE
GROUND. IN GENERAL AM IN A CLEAN UP MODE THIS EVENING WITH RESPECT
TO THE HEADLINES. ONCE PRECIP ENDS AND CURRENT HEADLINES ARE CLEARED
OUT...WIND CHILL ADVISORIES MAY BE ISSUED DUE TO THE WINDS AND
STRONG CAA.
WOLTERS
&&
.AVIATION...
HAVE IFR PREVAILING WITH TEMPO FOR LIFR DUE TO MODERATE SN AS BANDS
LIFT NORTHEAST. OPTED FOR THE TEMPO BECAUSE DO NOT ANTICIPATE A
PROLONGED PERIOD OF FORCING FOR MODERATE TO HEAVY SN. WINDS WILL
INCREASE BY 06Z FROM THE NORTHWEST. IF BLSN DOES NOT BECOME AN
ISSUE...CONDITIONS SHOULD IMPROVE TO MVFR BY 12Z. THOUGH DO NOT HAVE
MUCH EXPERIENCE WITH FORECASTING BLSN...SO MAY BE A TAD ON THE
OPTIMISTIC SIDE. WILL MONITOR.
WOLTERS
&&
.PREV DISCUSSION.../400 PM CST TUE DEC 8 2009/
ENERGETIC UPPER TROUGH WAS MOVING INTO WESTERN KANSAS AT 21Z. STRONG
PV ANOMALY WAS ROTATING NORTHEAST ACROSS KANSAS. IR SATELLITE SHOWS
INCREASING ENHANCED CLOUDS ACROSS SOUTHWEST AND CENTRAL KANSAS.
RADAR SHOWING SOME CONVECTIVE BANDS OF SNOW MOVING ACROSS NORTH
CENTRAL AND NORTHEAST KANSAS WITH SNOWFALL RATES AROUND AN INCH AN
HOUR. MAIN CHALLENGE HAS BEEN THE TRANSITION ZONE ACROSS PARTS OF
NORTHEAST AND EAST CENTRAL KANSAS. AREAS FROM VALLEY FALLS INTO
TOPEKA AND COUNCIL GROVE WERE TRANSITIONING BACK TO SLEET AT LATE
AFTERNOON. AREAS FURTHER SOUTHEAST OF THE TURNPIKE WERE MAINLY A MIX
OF RAIN AND SOME FREEZING RAIN. AS THE UPPER LOW APPROACHES THIS
EVENING EXPECTING THE COLUMN TO COOL FOR A CHANGE OVER BACK TO ALL
SNOW ACROSS EAST CENTRAL KANSAS THIS EVENING. SNOWFALL AMOUNTS
TONIGHT SEE AN ADDITIONAL ONE TO FOUR INCHES OF NEW SNOW THIS
EVENING ACROSS THE CWA. WILL MAINTAIN THE WINTER STORM WARNING FOR
PART OF NORTH CENTRAL AND NORTHEAST KANSAS TONIGHT. ALONG THE
NEBRASKA BORDER FROM CONCORDIA TO HIAWATHA HAVE ISSUED A BLIZZARD
WARNING FOR TONIGHT INTO WEDNESDAY MORNING. CALLS TO COUNTIES HAVE
YIELDED AROUND 6 TO 10 INCHES OF DRY POWDERY SNOW AND WITH LIGHT
WINDS WERE ALREADY CAUSING DRIFTS. WILL LIKELY SEE BLIZZARD
CONDITIONS ACROSS THE NORTHERN BORDER AREA TONIGHT AND WEDNESDAY
MORNING.
VERY COLD ARCTIC AIR WILL MOVE IN BEHIND THE SYSTEM TONIGHT AND
WEDNESDAY. HAVE LOWERED TEMPERATURES A FEW DEGREES TONIGHT AND MADE
ONLY SLIGHT ADJUSTMENTS TO HIGHS ON WEDNESDAY. WIND CHILLS WILL
RANGE FROM MINUS 2 TO MINUS 20 ACROSS THE CWA TONIGHT THEN MINUS 5
TO MINUS 15 IN THE MORNING HOURS.
53
ARCTIC AIR WILL REMAIN IN PLACE ACROSS THE CWA WEDNESDAY NIGHT.
DECREASING CLOUDS/WINDS AND SNOW COVER IN MUCH OF THE CWA WILL ALLOW
FOR ANOTHER VERY COLD NIGHT WITH READINGS RANGING FROM -5 TO -8
ACROSS THE DEEPER SNOW COVERED AREAS OF THE NORTHWEST HALF OF THE
CWA TO SINGLE DIGITS OVER THE SOUTHEAST CORNER. WITH 5 TO 10 KTS OF
WIND STILL EXPECTED ACROSS THE CWA...WIND CHILLS IN THE NORTHERN AND
WESTERN CWA COULD BE IN THE 15 TO 25 BELOW ZERO RANGE. THEREFORE
WINDCHILL ADVISORIES MAY NEED TO BE CONSIDERED BY LATER SHIFTS.
TEMPERATURES THROUGH THE END OF THE WEEK WILL BE STRONGLY AFFECTED
BY THE SNOW COVER/SNOW DEPTH THAT IS LEFT FROM TODAYS STORM. FOR
NOW...WITH SUCH A COLD START TO THE DAY THURSDAY...WILL HAVE HIGHS
RANGING FROM THE TEENS IN THE DEEPER SNOWPACK TO 20S OVER THE EAST
CENTRAL.
WINDS WILL BECOME MORE SOUTHERLY/SOUTHEASTERLY BY FRIDAY AS WAA AS
THE UPPER LEVEL FLOW BECOMES MORE ZONAL. WILL KEEP A LOW POP GOING
ACROSS THE FAR SOUTHERN CWA FOR RAIN/SNOW INTO FRIDAY NIGHT. HAVE
RAISED HIGHS FRIDAY AND SATURDAY INTO THE UPPER 20S NORTH TO MID 30S
SOUTH AND KEPT THEM IN THAT RANGE INTO EARLY NEXT WEEK AS ANOTHER
COLD FRONT SHOULD MOVE THROUGH THE AREA LATE SATURDAY TO HALT ANY
ADDITIONAL WARMING OR SNOW MELT IN THE NORTH. LOWS WILL GENERALLY
BE FROM THE TEENS NORTH TO THE LOWER 20S SOUTH.
MODELS DIFFER ON HOW FAR NORTH THE NEXT SYSTEM DIGS INTO THE PLAINS
BY EARLY NEXT WEEK...BUT FOR NOW LEANED TOWARDS THE EC MODEL AND
HAVE INTRODUCED A CHANCE FOR LIGHT SNOW OVER THE NORTH AND EAST ON
SUNDAY/SUNDAY NIGHT...THEN DRY INTO TUESDAY. THIS IS A SLOWER AND
FURTHER SOUTH TRACK THAN THE GFS.
63
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
BLIZZARD WARNING UNTIL 9 AM WEDNESDAY FOR KSZ008-KSZ009-KSZ010-
KSZ011-KSZ012-KSZ020.
WINTER STORM WARNING UNTIL 6 AM WEDNESDAY FOR KSZ021-KSZ022-
KSZ023-KSZ024-KSZ026-KSZ034-KSZ035-KSZ036-KSZ037-KSZ038-KSZ039.
WINTER WEATHER ADVISORY UNTIL 6 AM WEDNESDAY FOR KSZ040-KSZ054-
KSZ055-KSZ056-KSZ058-KSZ059.
&&
$$
