FXUS63 KOAX 231137
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
537 AM CST WED DEC 23 2009

.DISCUSSION...TODAY THROUGH FRIDAY NIGHT.

88D MOSAIC THIS MORNING SHOWING PCPN OVER THE CNTRL PLAINS PUSHING
NWD. RETURNS HAVE ALREADY REACHED THE SRN CWA. CALLS DOWN THERE
INDICATE IN-TOWN ROADS OK SO FAR BUT RURAL AREAS HAVE BECOME SLICK.
THIS WAS CORRESPONDING WELL WITH HRLY LAPS SOUNDING PCPN TYPE
SOUNDINGS DATA OVERLAID ON REFLECTIVITY LOOP. MESSY WEATHER ON TAP
THRU THE FCST PD ALL IN PART TO DUEL SHORTWAVE TROFS EMBEDDED IN WRN
CONUS LONGWAVE TROF. SATL PIX SHOWING SRN ENERGY WAS OVER THE SRN
ROCKIES WITH THE NRN PIECE DROPPING SWD ACROSS ALBERTA. SEEMS TO BE
VERY GOOD MODEL AGREEMENT THAT AS THE LONGWAVE TROF DRAWS CLOSER TO
THE PLAINS...PHASING OF THE TWO WAVES WILL OCCUR RESULTING IN
FORMATION OF DEEP CLOSED UPPER LOW BY FRIDAY MORNING. AT THAT
POINT...BLOCKING DOWNSTREAM WILL SLOW DOWN LARGE SCALE FLOW INTO THE
EARLY PART OF THIS WEEKEND. NEEDLESS TO SAY...WITH STOUT MOISTURE ON
TAP COUPLED WITH IMPRESSIVE BUT SLOW MOVING LARGE SCALE LIFT...
SIGNIFICANT PCPN ACCUMULATIONS WILL BE REALIZED OVER THE CWA BEFORE
EVENTS END ON SATURDAY. THE BIGGEST CONCERN THOUGH IS TIMING PCPN
CHANGE THEN PIN-POINTING AREA OF GREATEST SNOW ACCUMULATION. ATTM...
IS SEEMS AREAS GENERALLY SOUTH OF THE I-80 CORRIDOR WILL BE THE PCPN
TYPE PROBLEM CHILD THROUGH AT LEAST THURSDAY MORNING WHEN ENOUGH CAA
FILTERS IN FOR EVENTUAL CHANGE OVER TO ALL SNOW. BY THEN...WINDS WILL
INCREASE SIGNIFICANTLY OVER THE CWA IN RESPONSE TO DEEPENING SFC LOW
PRESSURE OVER ERN KS/WRN MO. LIKELY THAT AREAS OF BLOWING SNOW WILL
RESULT IN NEAR WHITE OUT CONDITIONS THURSDAY MORNING INTO FRIDAY
AFTN. AS MENTIONED...MODELS ADVERTISING CLOSED UPPER LOW EVENTUALLY
GETTING HUNG UP OVER MID MS VLY REGION AND BECOMING NEARLY STACKED.
WITH NEARLY PERSISTENT MID LYR TRANSVERSE AGEOSTROPHIC LIFT HANGING
OVER THE NEB/IA BORDER...SEEMS LOGICAL THAT FOCUS FOR GREATEST PCPN
AMOUNTS WILL BE THERE. HOWEVER...HIGHEST SNOW TOTALS IN GENERAL WILL
BE FOUND OVER PORTIONS OF NERN NEB/NW IA DUE TO LONGER DURATION OF
COLDER AIRMASS...FAVORABLE UPPER DIVERGENCE AND MOIST DENDRITIC
OMEGA. OTHERWISE...DRY CONDITIONS THE REST OF THE WEEKEND.

AVIATION...
TAF SITES KOFK/KOMA/KLNK

06Z TAFS

IFR CONDS EXPECTED THRU THE PERIOD. MAIN UNCERTAINTY ATTM IS PRECIP
TYPE AT OMA/LNK. SHLD BE ALL SNOW AT OFK STARTING BY EARLY AFTN AND
THRU THE EVNG. SFC TMPS AT BOTH OMA/LNK ARE GOING TO BE VERY CLOSE
TO FREEZING. PRECIP LIKELY TO START OUT AS FREEZING RAIN AT BOTH
SPOTS BUT THEN MAY GO OVER TO RA THIS AFTN AT BOTH...BUT ESPECIALLY
OMA. LIKELY TO GET A PRECIP BREAK AT ALL 3 TAFS SITES BY LATE AFTN
OR EARLY EVNG BEFORE ANOTHER BATCH OF PRECIP MOVES IN TONIGHT. EVEN
WHEN PRECIP IS NOT OCCURRING CONDS SHLD BE IFR. MAY SEE SOME LIFR AT
OFK THIS AFTN WITH THE SN.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR NEZ034-
     045-051>053-065>068-078-088>090-092.

     WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE FRIDAY NIGHT
     FOR NEZ034-045-051>053-065>068-078-088>093.

     WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR NEZ011-012-
     015>018-030>033-042>044-050-091-093.

     WINTER STORM WARNING FROM NOON TODAY TO 6 AM CST SATURDAY FOR
     NEZ011-012-015>018-030>033-042>044-050.

IA...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR IAZ043-
     055-056-069.

     WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE FRIDAY NIGHT
     FOR IAZ043-055-056-069-079-080-090-091.

     WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR IAZ079-080-090-
     091.

&&

$$

DEE/JB