FXUS63 KOAX 241530
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
930 AM CST FRI DEC 24 2010
.DISCUSSION...
TWEAKED THE FORECAST SLIGHTLY TO ALLOW FOR ONE MORE BATCH OF LIGHT
SNOW ACROSS NORTHWEST IOWA/SOUTHEAST SOUTH DAKOTA THAT WILL LIKELY
SLIDE EAST SOUTHEAST DOWN THE MISSOURI RIVER THROUGH THE AFTERNOON...
AFFECTING AREAS NORTH AND NORTHEAST OF OMAHA AND COULD SEE ANOTHER
INCH THROUGH THE DAY IN THOSE AREAS...THUS LEFT THE EXISTING
WINTER WEATHER ADVISORY INTACT. ELSEWHERE...CLOUDY SKIES WILL
CONTINUE...AND A STRAY FLURRY HERE OR THERE...BUT NOTHING
SIGNIFICANT. WHILE CLOUDY SKIES REMAIN OVERNIGHT...THERE COULD BE A
PERIOD OF EVENING FLURRIES FROM SOUTH AND EAST OF OMAHA IN THE
EVENING AS H70 TEMPS REMAIN IN THE DENDRITIC RANGE...BUT NO
ACCUMULATION AT ALL THIS EVENING.
DEWALD
&&
.PREV DISCUSSION... /ISSUED 342 AM CST FRI DEC 24 2010/
DISCUSSION...
SYNOPSIS...00Z UPPR AIR ANLYS INDCD SPLIT FLOW PATTERN ACRS THE
CONUS. SRN STREAM SYSTEM ASSOCIATED WITH NEAR 100 M H5 HEIGHT
FALLS WAS LOCATED OVR CNTRL NM. IN THE NRN STREAM...75 KT H3 JET
WAS TOPPING THE GREAT BASING RIDGE. AT H5...A POSITIVE TILTED
SHRTWV TROF WAS ANALYZED FM CNTRL ND INTO WRN NEB. AT H7 THE LO
WAS LOCATED JUST WEST OF ABR WITH THRML GRADIENT EXTNDD SEWD THRU
NW IA TO NEAR DVN. A GOOD DEAL OF MOISTURE EXTNDD FM THE GULF
COAST INTO THE CNTRL PLAINS WITH A +7 DP TO NEAR OKC. 09Z SFC
ANLYS INDCD LO PRES OVR ERN KS WITH AN INVERTED TROF NWD THUR ERN
NEB INTO SE SD.
FORECAST...CURRENT SYSTEM CONTS TO BE MESSY FOR THE FA PROVIDING
SEVERAL FORECAST PROBLEMS. H3 JET SHLD DIVE INTO THE BASE OF THE
NRN STREAM SHRTWV TROF THIS MRNG AND ALLOW FOR THE SYSTEM TO GET
BETTER ORGANIZED OVR THE MID MS RIVER VALLEY TODAY. H7 LO SHLD
TRACK GENERALLY ALNG 00Z ANALYZED THERMAL GRADIENT THRU NW IA AND
INTO SE IA TODAY. MODELS SEEM TO HAVE A GOOD HANDLE ON THIS PART
OF THE FORECAST FOR TODAY. THE PROBLEM FOR OUR FORECAST AREA HAS
BEEN GETTING...AND THEN MAINTAINING MID LVL SATURATION...AND THIS
SHLD CONT TO BE A PROBLEM THRU TODAY. IN ADDITION...WITH THE H7
CIRCULATION GOING OFF TO OUR EAST...MUCH OF OUR FRONTOGENETIC
FORCING IN OUR FA IS BELOW H7...AND THUS IN A REGION THAT IS NOT
DENDRITIC. EVEN THOUGH IT WL LIKELY SNOW AT TIMES /MAINLY OVR WRN
IA/...IT WILL HAVE A HARD TIME ACCUMULATING TO ANY SIG AMOUNTS FOR
OUR FA GIVEN THE MORE NEDDLE TYPE OF SNOW CRYSTAL. WE HAVE ALSO
BEEN GETTING NUMEROUS REPORTS OF FREEZING DRIZZLE OVR THE CNTRL
AND SRN FA AHEAD OF THE INVERTED TROF IN THE LO LVL WAA REGIME. ONCE
THIS SFC TROF PASSES THOUGH THE FZDZ SHLD COME TO AN END. GIVEN
ALL ABOVE WE HAVE DECIDED TO END THE ADVRY FOR ALL OF OUR NEB
COUNTIES AT 6 AM WITH THE INVERTED TROF PASSAGE...AND THEN CONT
THE IA PORTION THRU 21Z TODAY. WRN IA MAY SEEN AN ADDITIONAL INCH
AND WE HAVE ALREADY HAD A REPORT OF 3 INCHES NEAR HNR. OVR ERN
NEB...WE SHLD CONT TO SEE SOME FLURRIES PER POINT FORECAST
SOUNDINGS...BUT ADDITIONAL ACCUMULATIONS SEEM UNLIKELY ATTM. TMPS
ARE GETTING OFF TO A WARM START TODAY...AND THERE REALLY ISN'T
MUCH IN THE WAY OF COLD AIR READY TO MOV INTO THE FA. THUS WE
HAVE INCREASED HIGHS TODAY MOST AREAS...BUT ESPECIALLY IN THE SW.
ALTHOUGH THE SYSTEM SHLD BE OUT OF THE FA BY TONIGHT...GIVEN THE
CURRENT IR SATELLITE IMAGERY...THE CLDS MAY HANG ON OVERNIGHT AND
HAVE INCREASED TO CLOUDY. THIS IS LIKELY TO LEAD TO A FAIRLY MILD
NIGHT DESPITE THE HIGH PRESSURE MOVG INTO THE FA. CLDS WL LIKELY
START TO CLEAR N TO S DURING CHRISTMAS DAY...BUT THERE IS SOME
POTENTIAL FOR CLDS TO FILL BACK IN WITH THE SUNSHINE...AND THUS
WILL HEDGE FOR SKY COVER ATTM. THERE IS A MUCH BETTER CHC OF
SEEING THE SUN STARTING ON SUN AND INTO THE DAY ON MON WITH HIGH
PRESSURE DOWN THE SPINE OF THE MO RIVER. THIS SHLD LEAD TO A COLD
NIGHT SUN INTO MON GIVEN THE FRESH SN COVER OVER W-CNTRL IA.
MODELS ARE IN FAIRLY GOOD AGREEMENT IN MOVING ANOTHER WEAK TROF
THRU THE FA MON NIGHT INTO TUES...BUT ATTM IT APPEARS TO BE DRY.
REMOVED FZDZ MENTION THIS FAR OUT IN THE FORECAST AS IT IS A TRACE
EVENT...AND GIVEN THE CURRENT MODELS IT LOOKS UNLIKELY. OTHERWISE
WARMED TMPS INTO MID WEEK WITH BOTH THE GFS/EC INDCG GOOD WARMING
POTENTIAL. NO CHANGES WERE MADE PAST WED.
BOUSTEAD
AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
IFR TO LIFR CONDITIONS EXIST AT MOST SITES /WITH AN MVFR HOLE
AFFECTING KOFK NEAR THE SURFACE INVERTED TROUGH/...AND THIS WILL
CONTINUE INTO THE MORNING HOURS. PRECIP IS MOVING THROUGH THE
AREA...AND ANY LINGERING PRECIP SHOULD WIND DOWN THROUGH THE MORNING
HOURS...WITH PRECIP HANGING ON LONGEST AT KOMA. PRECIP TYPE SHOULD
BE MOSTLY FZDZ WITH SOME MIXING WITH LIGHT SNOW. VIS HAS BEEN
REDUCED IN THE PRECIP AREAS TO AROUND 1-2SM...BUT SHOULD IMPROVE
DURING THE DAY AS PRECIP WINDS DOWN. EXPECT IFR TO LOW-END MVFR
CIGS TO LINGER FOR MUCH OF THE DAY AND POSSIBLY EVEN INTO TONIGHT AT
ALL SITES AS LOW-LEVEL MOISTURE BLANKETS THE AREA. WINDS WILL
SWITCH TO NORTHERLY/NORTHWESTERLY DURING THE DAY...WITH SOME
INCREASE IN SPEEDS...THOUGH STILL EXPECTED TO REMAIN BELOW 10-12KT.
MAYES
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...WINTER WEATHER ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR IAZ043-
055-056-069-080.
&&
$$