FXUS63 KOAX 142055
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
255 PM CST MON DEC 14 2009

.SHORT TERM...TONIGHT THROUGH THURSDAY
WINDS AND WEATHER ARE CALMING TODAY AFTER OVERNIGHT FREEZING DRIZZLE 
AND SNOW.  SUBJECTIVE 12Z UPPER AIR ANALYSIS INDICATES WSWLY 
UPPER-LEVEL FLOW ACROSS THE CNTRL US...WITH MAIN UPPER-LEVEL JET 
ENERGY PULLING AWAY TO THE EAST.  SHORTWAVES WERE ANALYZED AT 12Z 
FROM CNTRL NEB INTO WRN KS...FROM SRN NEV THROUGH THE AZ/CA 
BORDER...AND FROM SRN MB/SASK/AB THROUGH NWRN MT...ALONG WITH DEEP 
UPPER LOW CENTERED IN FAR NRN QB.

MAIN FORECAST CONCERN THROUGH THURS LIES IN TEMPS...AS WEATHER IS 
QUIET THROUGH THE NEXT FEW DAYS.  AS CLOUDS AND WINDS DIMINISH 
TONIGHT...TEMPS SHOULD DROP WELL BELOW ZERO ACROSS THE AREA.  DID 
NUDGE TEMPS UP A DEGREE OR TWO IN A FEW PLACES.  RESULTING 
COMBINATION OF TEMPS AND DECREASING WIND SPEEDS DID NOT PUSH WIND 
CHILL FCST BELOW -20F CRITERIA...AND WILL NOT ISSUE ANY HEADLINES 
WITH THIS PACKAGE. WOULD NOT RULE OUT A SITE OR TWO MARGINALLY
MEETING CRITERIA FOR A SHORT TIME TONIGHT...BUT MARGINAL/ISOLATED
NATURE COMBINED WITH CALMING WINDS WAS ENOUGH TO ERR ON THE SIDE
OF NO ADVISORY. KEPT HIGHS TMRW IN THE UPPER SINGLE DIGITS TO LOW
TEENS...AGAIN A DEGREE OR TWO ABOVE THE PREVIOUS FORECAST BUT
STILL BELOW GUIDANCE...WITH LITTLE OR NO WIND THROUGH THE DAY BUT
ALSO WITH CLEARING SKIES. AS SFC HIGH PASSES THROUGH THE CWA
TMRW...WINDS WILL RETURN TO SRLY IN ITS WAKE. THINK MINS TMRW NT
MAY OCCUR AROUND 06-09Z...WITH STEADY OR SLOWLY RISING TEMPS
THROUGH THE OVERNIGHT AS SRLY WINDS INCREASE AND A FEW HIGHER-
LEVEL CLOUDS POSSIBLY EXTEND INTO THE NRN CWA...AND DID INCLUDE
THE NON-DIURNAL TEMPS IN THE GRIDS. WEAK SHORTWAVE IS PROGGED TO
MOVE THROUGH ND/NRN MN ON WED NT/THURS...AND WHILE IT WILL BE TOO
FAR NORTH TO AFFECT SENSIBLE WEATHER...IT MAY DRAG A WEAK WIND
SHIFT AND A FEW CLOUDS THROUGH THE CWA. HAVE INCREASED CLOUD COVER
WED NT/THURS..ESPECIALLY WITH LOW-LEVEL MOISTURE PROGGED TO
INCREASE. ALSO NUDGED MAX TEMPS DOWN WED/THURS AS TEMPS HAVE
STRUGGLED TO REACH THE 30S IN THIS REGIME...THOUGH WED HAS THE
BETTER WARM-UP POTENTIAL AHEAD OF WIND SHIFT AND LIKELY WITH FEWER
CLOUDS.

.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
NO HEAVY PCPN EVENTS ARE EXPECTED IN THIS PERIOD...BUT WILL KEEP A 
20-30 PERCENT CHANCE OF SNOW FOR AT LEAST PARTS OF THE AREA FROM 
THURSDAY NIGHT INTO FRIDAY NIGHT. BLOCK OUT EXTENDING FROM THE 
ATLANTIC UP INTO GREENLAND BETWEEN ABOUT 20 AND 40 DEGREES WEST IS 
STILL A FAIRLY BIG FACTOR IN THE HEMISPHERIC PATTERN. THAT BLOCK 
WILL RETROGRADE A LITTLE DURING THE PERIOD. CLOSER TO OUR AREA...
A 500 MB RIDGE WILL BE BUILDING OVER THE WESTERN UNITED STATES AT
00Z FRIDAY. THE 12Z MODELS WERE IN FAIR AGREEMENT WITH THE LARGE
SCALE PATTERN TO START OUT...BUT DIFFERENCES WITH LOCATION AND
TIMING OF SHORTWAVES START TO SHOW UP AND INCREASE. ALTHOUGH THE
ECMWF WAS SLIGHTLY FAVORED TOWARD THE BEGINNING OF THE PERIOD...
THE 12Z GFS WAS THE BEST COMPROMISE FOR THE PATTERN AT 12Z SUNDAY.
HOWEVER...THE MODEL SPREAD IS HIGH ENOUGH TO PUSH FORECASTER 
CONFIDENCE TO BELOW NORMAL FOR SUNDAY AND MONDAY. STAYED FAIRLY 
CLOSE TO HPC GUIDANCE TEMPS.

&&

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

18Z TAFS

COLD SFC HIGH PRESSURE ENVELOPING THE CNTRL PLAINS WILL RESULT IN 
VFR CONDITIONS PREVAILING ALL SITES THRU THE FCST PD.

&&

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

$$

SHORT TERM...MAYES
LONG TERM...MILLER
AVIATION...DEE