FXUS63 KOAX 090921
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
321 AM CST SUN JAN 9 2011
.DISCUSSION...
NO BIG CHANGES FROM PREVIOUS FORECAST. MAIN CONCERN IS STILL SNOW
EVENT THAT WILL LAST INTO TUESDAY. WILL START THE WINTER WEATHER
ADVISORY AT ZFP ISSUANCE TIME THIS MORNING FOR NWRN PART OF THE
FCST AREA RATHER THAN AT 12Z. SNOW OVER SERN NE THIS MORNING IS
EXPECTED TO SHIFT FARTHER NORTH AS THE DAY GOES ON...SO OPTED TO
LEAVE THAT AREA OUT OF THE ADVISORY UNTIL TONIGHT.
SURFACE ANALYSIS AT 08Z SHOWED A RIDGE OF COLD HIGH PRES EXTENDING
FROM MAN CANADA THROUGH MN AND ERN IA INTO TN. LOW PRES WAS OVER
CO DOWN INTO WEST TX. EAST OR SOUTHEAST LOW LEVEL WINDS COVERED
THE LOCAL AREA. DEWPOINTS WERE IN THE SINGLE DIGITS TO MID TEENS.
WATER VAPOR STLT LOOP EARLY THIS MORNING SHOWED MAIN CLOSED LOW
OVER SRN ALTA. 500 MB CHART FROM 00Z HAD 12 HR HEIGHT FALLS OF UP
TO 150 METERS OVER SWRN ID. ALTHOUGH NOT MUCH OF A PLAYER FOR OUR
AREA...THE NEARLY CLOSED LOW OVER WEST TX HAD 12 HR HEIGHT FALLS OF
UP TO 100 METERS. LATEST GFS/ECMWF/CANADIAN/NAM WERE STILL IN FAIRLY
GOOD AGREEMENT WITH OVERALL DEVELOPMENT OF SYSTEM. ALTHOUGH IT MAY
BE CLOSE IN PARTS OF THE AREA (ESPECIALLY NERN NE THE NEXT 24 HRS)
...STILL EXPECT THAT SNOWFALL AMOUNTS WILL BE JUST UNDER WARNING
CRITERIA. THAT IS 6 INCHES IN 12 HRS OR 8 INCHES IN 24 HRS. WINDS
ARE STILL EXPECTED TO BE MAINLY UNDER 15 MPH UNTIL LATE MONDAY
NIGHT OR TUESDAY MORNING. WILL ALLOW HEADLINES TO STAY AS IS FOR
NOW BUT MAY NEED TO BE EXTENDED DEPENDING ON LIGHT SNOW AND OR
BLOWING AND DRIFTING SNOW MONDAY NIGHT/EARLY TUESDAY MORNING.
MODEL QPF VALUES ACROSS THE FORECAST AREA ARE MAINLY 0.60 TO 0.75
FROM THE 00Z GFS...0.7 TO 1.00 FROM THE 00Z NAM AND 0.35 TO 0.60
FROM THE 00Z ECMWF. 850-700 MB MIXING RATIOS FROM THE GFS FOR OMA
ARE MAINLY 2.0 TO 2.8 G/KG FROM 12Z SUN TO 12Z MON...THEN 1 TO 2
G/KG FROM 12Z MON TO 12Z TUE. OMEGA VALUES STILL MAINLY 4 MICROBES
PER SECOND OR LESS BELOW 600 MB.
CHANGES BEYOND TUESDAY WERE VERY MINOR. STILL LOOKS VERY COLD MID
WEEK WITH SOME MODERATION AHEAD OF WHAT LOOKS LIKE ANOTHER ARCTIC
PLUNGE FRIDAY OR SATURDAY.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
CONCERNS DURING THE PD WILL BE MVFR/IFR/LIFR CIGS ACCOMPANIED BY
SNOW. THE LARGE STORM SYSTEM OVER MONTANA WILL REMAIN OVER THE
MT/WRN DAKOTAS REGION FOR AN EXTENDED PD OF TIME AND WILL AFFECT THE
TAF SITES INTO EARLY NEXT WEEK WITH PDS OF LIGHT TO MODERATE SNOW.
CIGS HAVE BEEN LOWERING TO MVFR WITH LIGHT SNOW AND MVFR VSBYS AT
KOFK AND KLNK. WAA/UVV/ISENTROPIC LIFT CONTRIBUTING TO THE LIGHT
SNOW...BUT ALSO THERE IS MID AND UPPER LEVEL SUPPORT AS A RESULT OF
THE H5 AND H3 JETS; ONE HEADING INTO THE CNTRL ROCKIES AND THE OTHER
EXTENDING FROM THE MID ATLANTIC STATES INTO IOWA.
LOOK FOR DETEORIORATING CONDITIONS AT ALL THREE SITES THIS MORNING
WITH MVFR/IFR CIGS/VSBYS AND IFR/LIFR AT KOFK.
THERE ARE SOME HINTS THAT THE CIGS/VSBSY MAY BE MORE VARIABLE AT
KLNK AND KOMA AS SOME RELATIVELY DRIER AIR TRIES TO WORK IN FM THE
SOUTH. CIGS WOULD BE MVFR WITH SOME IFR WITH THIS INITIAL AREA OF
LIFT..BUT WOULD SEE IMPROVEMENT BACK TO MVFR. ANOTHER AREA OF LIFT
INCREASES SNOW RATES THIS AFTERNOON AND EVENING...SO WOULD AGAIN
EXPECT IFR/LIFR CONDITIONS. SOUTHEAST WINDS WILL CONTINUE THRU THE
PD AROUND 6-12KTS.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
TUESDAY FOR NEZ034-044-045-051>053-066>068-078-088>093.
WINTER WEATHER ADVISORY UNTIL 6 PM CST MONDAY FOR NEZ011-012-
015>018-030>033-042-043-050-065.
IA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
TUESDAY FOR IAZ043-055-056-069-079-080-090-091.
&&
$$
DISCUSSION...MILLER
AVIATION...ZAPOTOCNY