FXUS63 KTOP 090935
AFDTOP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
335 AM CST WED DEC 9 2009
.DISCUSSION...
UPPER TROF AXIS WAS FROM THE WESTERN DAKOTAS INTO WESTERN KANSAS AT
0Z WITH EXPECTED 12HR HEIGHT FALLS OF 150M REPORTED AT TOP. 105KT
500MB JET WAS OBSERVED AT DFW...BRINGING A NEGATIVE TILT TO THE
UPPER TROF THIS MORNING AS IT PUSHES QUICKLY EAST. LIGHT SNOW
PERSISTS OVER MUCH OF THE AREA IN SATURATED SNOW GROWTH LAYER
THROUGH MUCH OF THE LOWER AND MIDDLE TROPOSPHERE. VERY STRONG
PRESSURE GRADIENT OVER EASTERN KANSAS AT 8Z WITH NEAR 3-HOUR
PRESSURE RISES OF NEAR 5MB. 500M PROFILER AND RADAR WINDS FROM 40
TO 50KT SUPPORTING SUSTAINED SPEEDS FROM 20 TO 30MPH WITH SOME
GUSTS AROUND 45MPH...RESULTING IN BLOWING AND DRIFTING OF THE
NEARLY FOOT OF SNOW IN NORTHERN AREAS.
GUIDANCE QUITE SIMILAR IN THE PEAK OF WIND SPEEDS OCCURRING IN THE
NEXT FEW HOURS...WITH SLACKENING GRADIENT ALLOWING SOME DECREASES TO
OCCUR THROUGH THE DAY. THOUGH SURFACE OBS HAVE BEEN REPORTING
VISIBILITIES GENERALLY OVER ONE MILE...LOCAL LAW ENFORCEMENT
INDICATES MUCH LOWER LEVELS WHERE THE HEAVY SNOW HAS FALLEN. WILL
CONTINUE WITH BLIZZARD WARNING AND WINTER STORM WARNING THROUGH THE
REST OF THE NIGHT...THOUGH MAY TRANSITION TO A WINTER WEATHER
ADVISORY FOR MUCH OF THE AREA FOR THE MORNING HOURS AS DRIFTING AND
COLD WIND CHILLS PERSIST PENDING THE WIND TRENDS. LOW LEVELS REMAIN
RATHER MOIST WITH DRYING TAKING PLACE FROM SOUTHWEST TO NORTHEAST
THROUGH MID AFTERNOON. EXPECT SOME FLURRIES TO PERSIST IN THE
SATURATED SNOW GROWTH LAYER THROUGH MUCH OF THE MORNING. MAX TEMPS
OF THE DAY MAY OCCUR JUST AFTER SUNSET IN MANY AREAS WITH COLD AIR
ADVECTION THROUGH THE EARLY AFTERNOON.
MODELS VARYING GREATLY WITH LOW TEMP PROGS FOR TONIGHT. HAVE LITTLE
DOUBT THAT TEMPS WILL FALL BELOW ZERO IN DEEP SNOW AREAS WITH LIGHT
WINDS AND LITTLE CLOUD...BUT NAM APPEARS A BIT OVERDONE WITH 925MB
WINDS REMAINING IN THE 20KT RANGE AND FACTORING IN CURRENT TEMPS IN
WESTERN NEBRASKA. DESPITE THE LIGHT WINDS...WIND CHILL VALUES WILL
AGAIN DIP INTO ADVISORY RANGE...BUT WILL LET LATER SHIFTS FINE TUNE
THE LOCATION AND TIMING.
SLOW WARMING TREND IN ORDER FOR THE END OF THE WEEK. LIGHT WINDS
AGAIN EXPECTED THURSDAY NIGHT BUT WEAK WARM AIR ADVECTION AND SOME
CIRRUS SHOULD KEEP TEMPS ABOVE ZERO. NOT SEEING MUCH MOISTURE RETURN
TO SUPPORT PRECIP CHANCES DESPITE PERSISTENT ISENTROPIC LIFT...AND
REMOVED SMALL POPS IN THE SOUTHEAST.
65
&&
.AVIATION...
IFR VSBY WITH LIGHT SN WILL PERSIST THROUGH ABOUT
09Z. THINK THAT SN HAS BEEN WET ENOUGH THAT VSBY SHOULD REMAIN
ABOVE 1/2SM. CIGS UPSTREAM ARE MVFR AND INITIALLY THOUGHT THAT
WITH THE PRECIP WOULD COME LOWER CIGS. OPTED TO KEEP WITH
PERSISTENCE THOUGH AND WILL LEAVE PREVAILING CIGS ABOVE 1000 FT.
STRONG NORTHWEST WINDS WILL CONTINUE THROUGH THE DAY
WEDNESDAY...AND THINK A STRATOCU DECK WILL HANK IN ACROSS TOP AND
FOE THROUGH THE DAY.
WOLTERS
&&
.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.
WINTER WEATHER ADVISORY UNTIL 6 AM WEDNESDAY FOR KSZ038-KSZ039-
KSZ040.
&&
$$
