FXUS63 KOAX 032103
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
303 PM CST THU DEC 3 2009

.SHORT TERM...TONIGHT THROUGH SUNDAY. WEAK SURFACE TROUGH EXTENDING
FROM WISCONSIN SOUTHWESTWARD THROUGH EASTERN NEBRASKA...COMBINED
WITH BULLSEYE OF STRONGEST HEIGHT FALLS ALOFT...CONTINUED TO
GENERATE SCATTERED FLURRIES THROUGH MID AFTERNOON...UNDER WHAT
APPEARS TO BE A MOSTLY DIURNAL CLOUD DECK IN OUR AREA. ON THE
PERIPHERY OF THE CLOSED CIRCULATION...WATER VAPOR ALSO INDICATED A
SLIGHT ENHANCEMENT MOVING THROUGH THE BLACK HILLS...WHICH WAS
ALSO GENERATING SOME FLURRIES ACROSS SOUTHWEST SOUTH DAKOTA AND
NORTHERN NEBRASKA. BOTH AREAS MAY BE FAR ENOUGH REMOVED TO
POSSIBLY PULL THE MENTION OF FLURRIES ACROSS OUR CWFA OVERNIGHT.
DIURNAL CLOUDS SHOULD TEND TO SCATTER OUT A BIT ACROSS NEBRASKA
AND PARTS OF WESTERN IOWA...THUS PREFER THE COOLER MET GUIDANCE
OVERNIGHT. 

THE TAIL END OF THE MOIST LOBES MOVES THROUGH THE MID MISSOURI
VALLEY REGION ON FRIDAY...BUT HAVE KEPT FLURRY MENTION OUT AT THIS
TIME. THERMAL TROUGH WILL STILL BE MOVING THROUGH THE AREA...SO
FORECAST MAX TEMPS WITH MORE OF A MET/MAV BLEND WITH JUST A BIT
MORE EMPHASIS ON THE MET ATTM. 

QUIET WEATHER THEN FOR FRIDAY NIGHT/SATURDAY...IN ADVANCE OF THE
NEXT TROUGH THAT WILL AFFECT THE REGION ON SUNDAY. SAID TROUGH IS
JUST NOW PUSHING INTO THE BRITISH COLUMBIA COAST BASED ON WATER
VAPOR IMAGERY...AND APPEARS TO BE WELL HANDLED BY ALL THE MAJOR MODEL
SUITES EXCEPT PERHAPS THE SREF...WHICH APPEARS TO BE TOO FAR NORTH.
THE NAM IS JUST A TAD SLOWER WITH THE PROGRESSION OF THE SYSTEM...AND
THAT WILL HAVE TO BE WATCHED. THE GFS ENSEMBLE WAS REASONABLE
SYNOPTICALLY...BUT SEEMED TO BE TOO LIGHT ON THE MEAN QPF...THUS
PREFER A BLEND OF THE OPERATIONAL GFS/ECMWF/GEM...WHICH ALL SUPPORT
SNOW DEVELOPING THROUGH THE DAY SUNDAY. SEVERAL FACTORS SUPPORT
THIS...INCLUDING DECENT HEIGHT FALLS ALOFT...A SLIGHTLY COUPLED
JET STRUCTURE WITH UPPER LEVEL DIVERGENCE BEING ENHANCED BY BOTH
RIGHT ENTRANCE AND LEFT EXIT REGION DYNAMICS. DECENT 700/500 MB
FRONTOGENESIS IS ALSO NOTED...WITH SLIGHTLY VERTICAL EQUIVALENT
POTENTIAL TEMPERATURE LINES ACROSS EASTERN NEBRASKA...AND SLIGHTLY
NEGATIVE EPV...ALL COINCIDENT WITH THE DENDRITIC GROWTH ZONE. HAVE
BOOSTED POPS TO 50 PERCENT...DESPITE LATEST MEX ONLY SUGGESTING 30
PERCENT...WITH SYSTEM LINGERING INTO SUNDAY NIGHT. NOT A LOT OF
SNOW POTENTIAL...BUT AT LEAST ACCUMULATING SNOW SEEMS PROBABLE.
GFS COBB GUIDANCE WAS SUGGESTING AN INCH OR TWO...AS WELL AS HIRES
ECMWF OUTPUT. ALSO FEEL THAT IF CURRENT MODEL TENDS HOLD...WE
SHOULD BE ABLE TO BOOST POPS INTO THE LIKELY RANGE WITHOUT TOO
MUCH TROUBLE FOR THIS EVENT.

.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY. VERY GOOD AGREEMENT
AMONGST GFS/ECM/GEM SHOWING PROGRESSIVE LARGE SCALE FLOW DURING
THE EXTENDED PERIODS RESULTING FROM AMPLIFYING ERN PAC RIDGE EARLY
NEXT WEEK WITH EJECTION OF PAC NW UPPER CLOSED LOW AND ASSOCIATED
CANADIAN AIRMASS INTRUSION. SCENARIO FURTHER SUPPORTED VIA HIGH
REMOP VALUES AND GEM ENSEMBLES. INITIAL VORT ENERGY QUICKLY PUSHES
ACROSS THE CNTRL PLAINS SUNDAY NIGHT WITH STRONG CAA REACHING THE
GULF STATES BY 12Z MON. APPEARS THAT BEST CHANCE FOR SNOW WOULD
MAINLY COME SUNDAY EVENING. AFT 06Z SUN...MODELS DEPICT BEST LIFT
SHIFTING TO THE MID MS VLY REGION WITH SUBSIDENCE QUICKLY FILLING
IN OVER THE CNTRL PLAINS. 

MONDAY NIGHT WRN TROF DIGS INTO THE 4 CORNERS REGION AND EVENTUALLY
EJECTS ONTO THE PLAINS TUESDAY NIGHT. ATTM... LIGHT SNOW ACTIVITY
APPEARS SOMEWHAT PROMISING MONDAY NIGHT THRU TUESDAY NIGHT TIME
FRAME AHEAD OF APPROACHING WAVE. MODELS IN DECENT AGREEMENT
INCREASING MID LVL WAA/ISENTROPIC UPGLIDE PRECEDING THE WRN WAVE
RESULTING IN GOOD OVERRUNNING SITUATION. AGAIN...PROGRESSIVE
NATURE OF INCOMING SYSTEM SUGGESTING ANY SN ACCUMULATION SHOULD BE
ON THE LIGHT SIDE. COLD PLUNGE INTO THE CNTRL PLAINS WITH THIS
SYSTEM LOOKS QUITE STRONG PER GFS/ECM AND ANTICIPATE MIN TEMPS
COME WED MORNING GENERALLY NEAR 10 ABOVE WITH HIGHS STRUGGLING TO
REACH 20.

&&

.AVIATION...
TAF SITES KOFK/KOMA/KLNK 

18Z TAFS

VFR CIGS HAD DEVELOPED ACROSS THE AREA THIS AFTERNOON WITH CIGS
BECOMING MVFR AT ALL THREE SITES AFTER 00Z AND CONTINUING THROUGH
THE REMAINDER OF THE FORECAST PERIOD.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&

$$

SHORT TERM...DEWALD
LONG TERM...DEE
AVIATION...FOBERT