FXUS63 KOAX 102054
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
254 PM CST MON JAN 10 2011
.SHORT TERM...TONIGHT THROUGH TUESDAY.
INVERTED SFC TROF AXIS EXTENDS FROM NWRN MO NWWD INTO NWRN IA THIS
AFTERNOON. HEAVIEST SNOW BAND IN NARROW DEFORMATION AREA HAS NOW
PUSHED TOWARD THE MO RIVER VALLEY AND WL CONTINUE TO MOVE EAST THRU
THE EARLY EVENING HOURS. BEHIND THE TROF...LIGHT SNOW CONTINUES WWD
INTO CNTRL NEB AND NWRLY SFC WINDS CONTINUE TO INCREASE IN SPEED.
WILL BE EXTENDING THE WINTER WEATHER ADVISORY TO 18Z TUE TO ACCOUNT
FOR BLOWING AND DRIFTING SNOW. IN ADDITION...WIND CHILL ADVISORY
CRITERIA WILL BE MET IN OUR NORTHWEST COUNTIES. IT REMAINS UNCERTAIN
AS TO HOW MUCH BLOWING AND DRIFTING WILL OCCUR. GIVEN THE INCREASE
OF SFC WINDS TO 15 TO 25 MPH WITH GUSTS TO 30 MPH OVERNIGHT AND THE
LIGHT AND FLUFFY NATURE OF THE SNOW...WE FEEL THAT SOME SIGNIFICANT
AREAS OF BLOWING AND DRIFTING ARE POSSIBLE OUT IN THE OPEN AREAS.
SFC WINDS SHOULD BEGIN TO DIMINISH LATER TUESDAY AFTERNOON AS A
1040MB ARCTIC HIGH MOVES IN.
KERN
.MID TERM...TUESDAY NIGHT THROUGH THURSDAY.
MODELS IN GOOD AGREEMENT BITTERLY COLD TEMPS ON TAP JET STREAM SOUTH
OF THE REGION AND SURFACE HIGH ENVELOPS THE CNTRL PLAINS. AS USUAL...
MAV/MET NOT HANDING ANTICIPATED EXTREME CONDITIONS AND ARE TOO WARM.
THEREFORE WILL UNDERCUT GUIDANCE AND PUSH WED/THURS LOWS DOWN TO
AROUND 10 BELOW. APPEARS THAT ADV CRITERIA FOR WIND CHILL WILL BE
CLOSE WED MORNING. SFC HIGH CENTER WILL NOT BE COMPLETELY OVER
THE CWA JUST YET AND MODELS GENERALLY PROGS NW WINDS 5 TO 10 MPH.
OTHERWISE...ELONGATED CHANNEL OF VORTICITY RUNNING DOWN FRONT SIDE
OF APPROACHING UPPER RIDGE SHOULD NOT BE A FACTOR. COMBINATION OF
NIL MID UPPER LYR QVECT CONVG SUGGESTING DPVA LIFT POTENTIAL BEING
OVERCOME BY THE MASSIVE CAA.
DEE
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY.
NORTHWESTERLY FLOW FORECAST TO BEGIN EXTENDED PD AS UPPER RIDGING
BUILDS A LTL EWD ACROSS ROCKIES AS CURRENT WX PRODUCING TROUGH/LOW
PUSHES ACROSS NERN U.S. WITH NWRLY FLOW OVER CNTRL PLAINS
OPERATIONAL MODELS HAVE NOT BEEN VERY CONSISTENT IN STRENGTH OF ANY
CLIPPER-TYPE WAVE AND SRN EXTENT OF ASSOCD COLD FRONTAL PASSAGES.
STILL APPEARS A WAVE TRACKS ACROSS UPPER MS VALLEY FRIDAY WITH WARM
ADVCTN AHEAD OF IT. SOME SORT OF FRONT DOES PASS THROUGH OR ATTEMPT
TO PASS THROUGH FORECAST AREA FRI/SAT BUT COLDER AIR DOES NOT SPILL
ACROSS CWA UNTIL EARLY SUNDAY...ACCORDING TO OPERATIONAL 12Z
GFS/00Z ECMWF...SOMEWHAT SLOWER THAN PAST FEW RUNS. AFTER THAT GFS
AND ECMWF DIVERGE EVEN MORE. 00Z ECMWF WAS STRONGER WITH A WAVE ON
SUNDAY CROSSING CNTRL PLAINS AND THUS HITS SNOW CHCS PRETTY HARD
COMPARED TO DRY 12Z GFS WHICH PUTS CWA BACK IN WARM ADVCTN AHEAD OF
A WEAK WAVE CROSSING ROCKIES. TIMING OF ANY OF THESE WAVES AND
STRENGTH OF COLD FRONTAL PASSAGE LEADS TO A LOW CONFIDENCE
FORECAST. TRIMMED BACK SNOW CHCS FRI WITH LTL SUPPORT FROM LATEST
OPERATIONAL MODELS...BUT DID NOT REMOVE ENTIRELY. LEFT PCPN TYPE AS
SNOW EVEN THOUGH OPERATIONAL H85 TEMPS OF GFS/ECMWF WERE ABOVE ZERO
BECAUSE PCPN WOULD PROBABLY BE DEPENDENT ON A FARTHER SW WAVE
PASSAGE AND STRONGER COLD PUSH WHICH SOME GFS MEMBERS STILL
FORECAST. SPREAD SMALL SNOW CHCS ACROSS ALL OF THE CWA SAT/SAT NGT
AS COLDER AIR SEEPS FARTHER S BUT LEFT SUNDAY DRY ATTM BECAUSE OF
LACK OF GFS SUPPORT AND LACK OF CONSISTENCY OF MODELS. ADJUSTED
TEMPERATURES UPWARD FIRST PART OF EXTENDED TO ACCOUNT FOR A SLOWER
ARRIVAL OF COLDEST AIR BUT KEPT THEM GENERALLY BELOW MEX BECAUSE OF
NEW DEEP SNOWPACK AND POSSIBILITY OF QUICKER/STRONGER FROPA OR
SOUTHERN PUSH TO CANADIAN/ARCTIC AIRMASS.
CHERMOK
&&
.AVIATION...
18Z TAFS
MVFR TO IFR CONDITIONS ARE EXPECTED OVERNIGHT. SNOW IS EXPECTED TO
TAPER OFF FROM WEST TO EAST THIS EVENING HOWEVER NORTHWEST SFC WINDS
WILL BE ON THE INCREASE. SUSTAINED 15 TO 25 KTS WITH GUSTS UP TO 30
KTS ARE POSSIBLE LATER THIS EVENING INTO THE OVERNIGHT HOURS CAUSING
BLOWING AND DRIFTING OF SNOW. THIS MAY REDUCE SFC VISIBILITIES DOWN
TO 3/4SM FROM OVERNIGHT THRU 18Z TUESDAY.
KERN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY UNTIL NOON CST TUESDAY FOR NEZ011-012-
015>018-030>034-042>045-050>053-065>068-078-088>093.
IA...WINTER WEATHER ADVISORY UNTIL NOON CST TUESDAY FOR IAZ043-055-
056-069-079-080-090-091.
&&
$$