FXUS63 KOAX 300105
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
705 PM CST MON NOV 29 2010
.UPDATE...
UPDATED ZONES/AFD FOR EXPIRATION OF WINTER WEATHER ADVISORY...NO
OTHER SIGNFICANT CHANGES ATTM.
&&
.DISCUSSION...
FLURRIES AND AREAS OF DRIFTING/BLOWING SNOW PERSIST IN NERN NEBR
AND WILL LIKELY CONTINUE AT LEAST INTO EARLY TONIGHT.
HOWEVER...PREV GRIDS PRETTY MUCH REFLECT THIS AND THIS UPDATE WAS
MAINLY FOR EXPIRATION OF WINTER WEATHER ADVISORY.
CHERMOK
&&
.PREV DISCUSSION... /ISSUED 332 PM CST MON NOV 29 2010/
SHORT TERM...TONIGHT THROUGH THURSDAY
12Z UPPR AIR ANLYS INDCD UPPR LVL TROF FM CNTRL CANADA TO THE HIGH
PLAINS. POTENT UPPR LVL SHRTWV WITH THE TROF WAS LOCATED OVR WRN
KS AT 12Z. THIS WAS ASSOCIATED WITH A 120 M H5 HEIGHT FALL AT
KDDC. PER AFTN WV IMAGERY THIS SHRTWV WAS NOW LOCATED OVR SE NEB.
STG THRML GRADIENT WAS NOTED AT H7 ACRS THE PLAINS WITH -13 C AT
UNR AND -1 C AT TOP. 21Z SFC ANLYS INDCD 999MB LO OVR SW IA WITH
THE STG CDFNT EXTNDD THRU ERN KS AND INTO THE SRN PLAINS. REGIONAL
RADAR MOSAIC INDCS DEFORMATION BAND EXTNDD FM SE SD INTO NE NEB.
MUST OF THE SENSIBLE WX OVR THE SHRT TERM IS IN THE TONIGHT
PERIOD. UPPR LVL SHRTWV WL CONT TO LIFT NEWD TAKING MUCH OF THE
LARGE-SCALE LIFT TO THE NRN PLAINS. WE EXPECT DEFORMATION BAND OVR
NE NEB TO SWEEP EWD WHILE THE SRN END WEAKENS WITH TIME AS BETTER
FORCING SHIFTS NWD. REPORTS FM THIS BAND HAVE BEEN PRETTY MINOR
/ALTHOUGH A QUICK HEAVY BURST OF SN HAS BEEN SEEN AT MANY
LOCATIONS WITH UP TO 2 INCHES REPORTED/...ALNG WITH SOME MINOR
REPORTS OF FZDZ AHEAD OF THE BAND. THUS WL HAVE THE HIGHEST POPS
IN THE NE FA THIS EVNG QUICKLY EXITING BEFORE MIDNIGHT. OTHERWISE
POINT FORECAST SOUNDINGS FOR THE CNTRL AND NRN CWA DOES INDC THAT
THE TOP OF THE SC LAYER GETS INTO THE -12 AREA OVERNIGHT AND THUS
A FEW FLURRIES SEEM POSSIBLE FOR A GOOD PART OF THE NIGHT
/ESPECIALLY ALNG HIGHWAY 92 AND N IN NEB AND HIGHWAY 30 IN IOWA/.
WIND WL THEN BECOME THE CONCERN AS PRESSURE GRADIENT CONTS TO
TIGHTEN OVERNIGHT. WINDS AT 925 MB ARE AROUND 40 KT AND 55 KT IN
THE NRN FA AT H85. BIGGEST CONCERN IS THE TIME OF DAY AND LACK OF
SUN TO MIX THE BOUNDARY LAYER TO GET SOME OF THESE WINDS TO THE
SFC. WILL COUNT ON STG LO-LVL CAA TO KEEP THE BOUNDARY LAYER MIXED
AND GET THE WINDS TO INCREASE AFTER MIDNIGHT. THUS HAVE ISSUED A
WIND ADVISORY AFTER THE WINTER WEATHER ADVISORY EXPIRES FOR THE
REST OF THE NIGHT FOR NE NEB. SOME CONCERN FOR BLOWING SN WHERE IT
HAS SNOWED TODAY...BUT AMOUNTS HAVE BEEN FAIRLY LOW AND ANY
BLOWING SN SHLD BE PRETTY ISOLATED...BUT WL MENTION IN THE GRIDS.
SYSTEM QUICKLY EXITS THE AREA ON TUESDAY BUT THE WINDS WL LIKELY
CONT INTO MID MRNG BEFORE STARTING TO SLOWLY DIMINISH THRU THE
DAY. SKIES WL CLR FM W TO E WITH SOME SC LIKELY TO CONTG IN THE
NORTH. SFC RIDGE AXIS THEN SHIFTS INTO THE FA ON TUESDAY NIGHT
LEADING TO A CHILLY NIGHT FOR A GOOD PART OF THE FA WITH WINDS
BECOMING LIGHT AND SKIES CLR. RETURN FLOW STARTS ON WED AHEAD OF A
VERY MINOR SHRTWV TROF MOVING INTO THE REGION FOR WED NIGHT. KEPT
THE FORECAST DRY ATTM...BUT MODELS DO INDC SOME WEAK LIFT ALNG THE
THERMAL GRADIENT AND IT MAY BE ENOUGH TO SQUEEZE OUT A FEW
FLURRIES. DID INCREASE LOWS ON WED NIGHT THROUGH FOR THE EXPECTED
CLD COVER. WK SYSTEM THEM MOVES E ON THURS BUT A GOOD DEAL OF CLDS
REMAIN.
BOUSTEAD
LONG TERM...THURSDAY NIGHT THROUGH MONDAY
SIMILAR TO YESTERDAY...FLOW PATTERN AT 500 MB
STARTS OUT FAIRLY FLAT ACROSS THE CONUS AT THE BEGINNING OF THIS
PERIOD. WEAK RIDGE OVER THE WESTERN PLAINS WILL PROGRESS EASTWARD
INTO FRIDAY. I GENERALLY USED A BLEND OF THE 12Z GEM AND 12Z ECMWF
FOR MOST OF THE FORECAST DETAILS. DECIDED TO INTRODUCE A SLIGHT
CHANCE FOR LIGHT RAIN OR LIGHT SNOW ACROSS PARTS OF NORTHEAST
NEBRASKA FRIDAY. ECMWF HAS BEEN FAIRLY CONSISTENT SHOWING
POTENTIAL...BUT IT HAS MAINLY BEEN TO OUR NORTH AND EAST. CHANCES
ARE BETTER FROM THE DAKOTAS INTO SOUTHERN MINNESOTA AND MUCH OF
IOWA. EXPECT A QUICK BLAST OF COLD AIR BEHIND THIS SYSTEM WITH
HIGHS FRIDAY IN THE 30S...BUT POSSIBLY EVEN COLDER THAN THAT NEAR
THE SOUTH DAKOTA BORDER.
DETAILS GET FUZZY FARTHER OUT...BY NEXT WEEKEND...BUT THE 12Z RUNS
OF TODAYS ECMWF AND GEM ARE IN DECENT AGREEMENT WITH THE LARGE SCALE
PATTERN. SOME LIGHT SNOW APPEARS POSSIBLE SUNDAY NIGHT OR MONDAY AS
A TROUGH DIGS SOUTH WITH NORTHERN BRANCH OF SPLIT FLOW PATTERN.
GFS MOS HIGH TEMPERATURES SEEMED TOO LOW FRIDAY...TOO WARM SATURDAY
THEN REASONABLE SUNDAY AND MONDAY.
MILLER
AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
LIGHT PRECIPITATION AND WINDS WILL BE THE PRIMARY FORECAST
CONCERNS. THE COLD FRONT HAS MOVED THROUGH THE AREA AND
TEMPERATURES HAVE DROPPED BACK INTO THE 20S AND 30S WITH NORTHWEST
WINDS OF 20 TO 30KTS. THESE WINDS WILL REMAIN STRONG THROUGH THE
ENTIRE TAF PD. SOME PATCHY FREEZING DRIZZLE WILL BE POSSIBLE AT
KOMA AND KLNK BEFORE 00Z THEN FLURRIES WILL BE POSSIBLE OVERNIGHT.
AT KOFK THE PRECIPITATION SHOULD BE ALL SNOW. LIFR CIGS AND VSBYS
SHOULD IMPROVE TO MVFR AS THE HEAVIER SNOW BAND MOVES OUT WITH
FLURRIES AFTER 23Z.
ZAPOTOCNY
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY UNTIL 6 AM CST TUESDAY FOR NEZ011-012-015>018-
030>033-042-043.
IA...NONE.
&&
$$
BOUSTEAD/MILLER/ZAPOTOCNY