FXUS63 KOAX 060946
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
346 AM CST SUN DEC 6 2009

.DISCUSSION...

SYNOPSIS...00Z UPPR AIR ANALYSIS INDCD DEEP UPPR LVL TROF OVR THE
NCTRL AND WRN US. TWO IMPORTANT FEATURES WITHIN THIS LARGE-SCALE
TROF WERE SHRTWV OVR NV ASSOCIATED WITH A 160 M H5 HEIGHT FALL AND
THE NEXT UPSTRM SHRTWV OVR BC ASSOCIATED NEAR 100 M H5 HEIGHT
FALLS. LATTER SYSTEM WAS ALSO ASSOCIATED WITH A 150 KT H3 JET
DIVING SWD. LITTLE IF ANY MOISTURE WAS OBSERVED AT H85 FM HERE TO
THE GULF COAST. 09Z SFC ANLYS INDCD LO PRES DVLP OVR NE NM WITH
CDFNT NEWD INTO ERN IA.

FORECAST...FORECAST CONTS TO FOCUS ON TWO WINTER WEATHER SYSTEMS.
THE FIRST /THE NV SHRTWV TROF/ WL BE MOVG EWD TODAY WHILE
WEAKENING AS IT MOVS INTO CONFLUENCE FLOW. H3 100 KT JET
ASSOCIATED WITH THIS SYSTEM WL MOV INTO THE HIGH PLAINS BY AFTN.
DOWNSTREAM JET OF 110 KT AT H3 WL SET UP OVR THE NRN PLAINS AND
SHLD ALLOW FOR FAVORABLE LARGE-SCALE SUPPORT FOR ASCENT. BEST
200-400 MB PRES ADVECTION MOVS INTO THE WRN CWA THIS AFTN AND
QUICKLY EXITS AFTER 06Z. MID LVL FRONTAL CIRCULATION CONTS TO LOOK
TO DVLP...AND MOST LIKELY ALONG HIGHWAY 30. H5 TO H7 DELTA-T ON
THE 00Z ANLYS INDCD ATMOSPHERE IS PRETTY STABLE ACRS THE CNTRL
PLAINS AND THUS CSI STILL NOT EXPECTED. THUS A GENERAL AND WIDESPREAD
LIGHT SNOW IS FORECAST. LACK OF MOISTURE AND SPEED OF SYSTEM ARE
ALSO GOING TO LIMIT SNOWFALL. NEVERTHELESS THE THERMAL GRADIENT
DOES LOOK SUFFICIENT TO PRODUCE A COUPLE INCHES. ALTHOUGH IMPACT
IS NOT HUGE ON A SUN...IT HAS BEEN A LONG WHILE SINCE MEASURABLE
SNOW HAS OCCURRED...AND SOME LOCATIONS HAVE YET TO SEE SN. THUS
HAVE ISSUED A WNTR WX ADVISORY FOR PARTS OF THE AREA EXPECTING TO
SEE 3-4 INCHES. SYSTEM SHLD EXIT THE AREA AFTER MIDNIGHT WITH CWA
DRY BY 12Z MON. GOING FORECAST IN PRETTY GOOD SHAPE WITH THIS
SYSTEM AND ONLY MINOR TIMING AND PLACEMENT CHANGES WERE MADE. TMPS
LOOKED TO BE ON TRACK FOR THE MOST PART.

THE SECOND SYSTEM /NOW DIVING SWD THRU WRN BC/ WL START TO IMPACT
THE AREA AS SOON AS MON EVNG. ALTHOUGH WELL TO THE
WEST...BROAD ISENTROPIC LIFT WL GET GOING MON EVNG AHEAD OF THE
SYSTEM. CURRENT FEELING IS THAT MODELS ARE OVERDOING THE WAA
PRECIP GIVEN THE MOISTURE AVAILABLE AND LACK OF MUCH FORCING ON
MON NIGHT...BUT GIVEN THE PERSISTENT WEAK LIFT SHLD SEE -SN GET
GOING WITH UP TO AN INCH OR TWO POSSIBLE BY 12Z TUE. MODELS ARE IN
GENERAL AGREEMENT WITH THE TRACK OF THE SYSTEM /WITH THE EXCEPTION
OF THE NAM WHICH WAS NOT USED/. THE EC AND CANADIAN ARE MUCH
STRONGER WITH THE DEEPENING SFC LOW...BUT THE GFS IS NOT TO FAR
BEHIND. MID LVL CIRCULATION NEVER DOES CLOSE OFF...AND THE SPEED
OF THE SYSTEM IS AN ISSUE...WHICH WILL LIMIT SNOWFALL TOTALS.
LARGE-SCALE FORCING FOR ASCENT DOES INCREASE DURING THE DAY ON
TUES AS THE NEGATIVELY TITLED WAVE MOVS INTO THE WRN HI PLAINS.
INTENSE BAROCLINIC ZONE WILL LEAD TO STG FRONTOGENESIS THRU THE
DAY PER CROSS SECTIONS FM THE GEM/EC/GFS. STRONGER MID LVL CAA
APPEARS TO LEAD TO LESS STABLE CONDITIONS ALNG THE FRONTAL SLOPE
AND THUS A BETTER TROP - FRONT RESPONSE IS EXPECTED. STILL NOT
OVERLY IMPRESSED WITH THE UPSTREAM MOISTURE WITH THE MODELS INDCG
4 G/KM SPEC HUM AT BEST...BUT DEGREE OF FORCING DOES INDC POSSIBLE
WRNG TOTAL SN. IN ADDITION THE GEM AND THE EC HAVE 50 KT AT 925 MB
AS THE SFC LO DROPS BELOW 985 MB OVR MO. THIS WLD LEAD TO
CONSIDERABLE BLOWING AND DRIFTING OF SN AND VERY DIFFICULT TRAVEL.
DESPITE THE EVENT BEING AT THE VERY END OF THE NORMAL WATCH
PERIOD...CONFIDENCE IS OVER 50 PERCENT FOR WRNG CONDITIONS IN SOME
PART OF THE AREA WITH A POSSIBLE HIGH END EVENT. THUS COORDINATED A
WNTR STRM WATCH FOR A GOOD PART OF OUR FA WITH THE SURROUNDING
OFFICES. NO CHANGES WERE MADE TO THE FORECAST PAST WED.

BOUSTEAD

&&

.AVIATION...

TAF SITES KOFK/KOMA/KLNK 

06Z TAFS

WINDS OUT OF THE NORTHEAST AS OF 06/09Z ACROSS THE FCST AREA...WITH 
WINDS EXPECTED TO SHIFT TO THE NORTH BY THE END OF THE FCST PERIOD 
FOR ALL THREE TAF SITES.  BKN-OVC HIGH CLOUDS ARE DOMINATE ACROSS 
THE ENTIRE FCST AREA WITH LOW CLOUDS ALREADY EFFECTING KOFK IN THE 
FORM OF MVFR CEILINGS AS OF 06/09Z.  CURRENT NORTHEAST FLOW WILL 
CONTINUE TO BRING INCREASING LOW LEVEL RH AND POTENTIAL IFR/MVFR 
CIGS AS THE MORNING PROGRESSES.  AS THE APPROACHING STORM SYSTEM 
MOVES ACROSS THE FCST AREA TODAY...LIGHT SNOW IS EXPECTED AROUND 
06/17Z TIMEFRAME FOR ALL THREE TAF LOCATIONS.  IFR VISIBILITIES ARE 
EXPECTED AFTER 06/18Z...WITH CONTINUED THREAT OF SNOW ACROSS THE 
REGION THROUGH THE AFTERNOON AND EVENING HOURS.

REESE

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY FROM NOON TODAY TO 3 AM CST MONDAY FOR 
     NEZ015-034-045-052-053-067-068.

     WINTER STORM WATCH FROM LATE MONDAY NIGHT THROUGH LATE TUESDAY 
     NIGHT FOR NEZ015>018-030>034-042>045-050>053-065>068-078-
     088>093.

     WINTER WEATHER ADVISORY FROM 9 AM THIS MORNING TO MIDNIGHT CST 
     TONIGHT FOR NEZ016>018-030>033-042>044-050-051-065-066-078.

IA...WINTER WEATHER ADVISORY FROM NOON TODAY TO 3 AM CST MONDAY FOR 
     IAZ043-055-056-069-079.

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

&&

$$