FXUS63 KOAX 160039
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
639 PM CST WED DEC 15 2010
.UPDATE...
PRODUCTS UPDATED AGAIN TO TAKE ADVISORY INTO SEWARD AND LINCOLN
AREAS.
&&
.DISCUSSION...
AREA OF MIXED PCPN CONTINUES TO MOVE EWD. WARM WEDGE ALOFT ON WRN
EDGE HAS BEEN PRODUCING FREEZING RAIN. FARTHER EAST...MIX OF
FREEZING RAIN AND SLEET TRENDING MORE TOWARD SNOW IN WEST CENTRAL
IOWA. PCPN SHOULD BE MAINLY BEFORE MIDNIGHT.
&&
.PREV DISCUSSION... /ISSUED 512 PM CST WED DEC 15 2010/
UPDATE...
ALL PRODUCTS HAVE BEEN UPDATED.
DISCUSSION...
WESTERN EDGE OF PCPN HAS BEEN SAGGING SWD AND WILL AFFECT AT LEAST
PARTS OF THE METRO AREA. SO...ADVISORY EXPANDED SOUTHWARD AND ALSO
EXTENDED ERN END OF ADVISORY UNTIL MIDNIGHT. A FEW OTHER SMALL
CHANGES MADE TO DETAILS OVERNIGHT.
PREV DISCUSSION... /ISSUED 321 PM CST WED DEC 15 2010/
SHORT TERM...TONIGHT THROUGH SATURDAY.
THE IMMEDIATE FORECAST CONCERN IS PCPN AMOUNT AND PCPN TYPE THROUGH
THIS EVENING. CHANCE OF MEASURABLE PCPN DROPS OFF QUICKLY BY ABOUT
MIDNIGHT BUT DID INCLUDE A MENTION OF FLURRIES OR PATCHY FREEZING
AFTER MIDNIGHT.
500 MB CHART FROM 12Z SHOWED A BROAD AREA OF 12 HOUR HEIGHT FALLS
OF OVER 50 METERS STRETCHING FROM SRN CA INTO WY AND MT. AT 300 MB
WINDS OF OVER 140 KTS WERE NOTED FROM THE ERN PACIFIC INTO CNTRL
NV AND NRN UT. WATER VAPOR IMAGERY SHOWED A CLOSED LOW NEAR THE
ALTA/SASK BORDER MOVING NW. STRONG MID LEVEL WINDS NOTED FROM SRN
CA EWD INTO KS...OK AND TX. CURRENT RADAR LOOP SHOWED A FAIRLY
DECENT AREA OF PCPN MOVING EWD ACROSS NERN NE. THIS SHOULD CONTINUE
TO PUSH QUICKLY EWD...WITH LARGEST IMPACTS JUST NORTH AND NORTHEAST
OF THE OMAHA AND COUNCIL BLUFFS AREAS. PCPN UP TO EARLY AFTN HAD
BEEN MIXED...WITH FREEZING RAIN AND SLEET. THINKING IS THAT MOST OF
THE PCPN THIS EVENING SHOULD BE SLEET OR SNOW...WITH ENHANCED LIFT
AND THEN LIGHT FREEZING DRIZZLE OR FLURRIES OVERNIGHT AS WE LOSE
THE ICE CRYSTALS ALOFT. WITH CLOUDS OVERNIGHT...MOS LOWS SEEMED A
BIT ON THE COOL SIDE.
THE THURSDAY THROUGH SATURDAY PERIOD LOOKS MAINLY DRY WITH BELOW
NORMAL TEMPERATURES. COLD HIGH PRESSURE WILL BUILD EWD FROM SWRN
CANADA AND THE NRN ROCKIES ACROSS THE NRN AND CNTRL PLAINS AT THE
SURFACE. ALOFT...FAIRLY FAST ZONAL FLOW SHOULD TRANSITION TO NW
FLOW AS A RIDGE DEVELOPS OVER THE ROCKIES BY SATURDAY.
LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY.
PRETTY GOOD AGREEMENT BETWEEN GEFS/CMCENS...AS WELL AS LATEST
DETERMINISTIC MODELS...DEPICTING A PRONOUNCED BLOCKING PATTERN
DEVELOPING RESULTING IN LARGE SCALE FLOW BECOMING STAGNANT AND
GRADUAL BUILDING OF UPPER RIDGE COVERING THE CNTRL CONUS NEXT WEEK.
AT THIS POINT...PROBLEMATIC AT BEST TRYING TO DETERMINE HOW MUCH OF
AN INFLUENCE BUILDING RIDGE WILL HAVE ON CWA TEMPS. BOTH THE GFS/ECM
ADVERTISING GREATEST LLVL TEMP MAGNITUDE GRADIENT SETTING UP AND
CUTTING NW-SE FROM ABOUT ERN MT TO SRN MO...WITH POTENTIAL FOR
CREATING MAX/MIN SPREAD 1OF 0 DEG OR SO BETWEEN WRN IA(COLDER SIDE)
AND ERN NEB(WARMER SIDE). OTHERWISE...EXCEPT FOR SMALL -SN POPS NRN
CWA SUN NIGHT....HAVE KEPT XTND PD DRY. GFS/ECM LAYING AREA OF QPF
MOSTLY ACROSS ERN SD/NRN IA IN ASSOCIATED WITH SPUNKY LITTLE
IMPULSE PASSING THRU THE AREA SUN NIGHT/MON MORNING TIME
FRAME.
AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
DETERIORATING CONDITIONS FOR THE REST OF THIS AFTERNOON INTO THIS
EVENING AS AN AREA OF FREEZING RAIN...SLEET AND LIGHT SNOW WILL
IMPACT THE TAF SITES...ESPECIALLY KOFK AND KOMA. HAVE MVFR AND
VSBYS CIGS MENTIONED THRU 04 OR 05Z AT KOFK AND KOMA WITH -FZRAPL
THEN -SN. KLNK IS FARTHER SOUTH AND THOUGHT THAT BY THE TIME THE
PRECIP STARTED THERE FM 00-04Z IT WOULD BE SNOW...HOWEVER WILL NEED
TO WATCH FOR PRECIP TYPE IF THE CHANGEOVER IS NOT AS QUICK.
SOUTHEAST FLOW WILL SWITCH AROUND TO THE NORTHWEST AT KOFK FIRST
AROUND 01Z...AND LATER AT KOMA/KLNK AFT 06Z.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR NEZ015-
033-034-043>045-050>053.
WINTER WEATHER ADVISORY UNTIL 9 PM CST THIS EVENING FOR
NEZ016>018-030>032-042-065-066-078.
IA...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR IAZ043-
055-056-069.
&&
$$
SHORT TERM...MILLER