FXUS63 KOAX 212114
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
314 PM CST TUE DEC 21 2010
.SHORT TERM...TONIGHT THROUGH FRIDAY.
FORECAST CONCERN IN SHORTER TERM REMAINS SYSTEM MOVING ONTO
PLAINS THURSDAY/FRIDAY PD. MODELS HAVE COME MORE IN AGREEMENT IN
TIMING WITH CLOSING SRN STREAM SYSTEM AND KEEPING MOST OF THE
ENERGY SOUTH OF THE CWA. HOWEVER...MINOR DIFFERENCES REMAIN WITH
QPF AMOUNTS...TIMING AND PLACEMENT.
BEFORE THEN...TNGT AND WEDNESDAY...EARLY AFTN STLT IMAGERY SHOWED
WEAK WARM ADVCTN DRIVEN MID CLOUDS OVER NEBRASKA SOUTHWEST OF
UPPER LOW SEGMENT OVR MN. LOW CLOUDS WERE CIRCULATING AROUND
SYSTEM FM NERN SD N AND EWD INTO ND AND MN. LARGE PACIFIC TROUGH
WAS APPROACHING OR/CA COAST AND AS THIS TROUGH MOVES ONSHORE LATE
TNGT...UPPER RIDGING AHEAD OF IT SHOULD BRING MORE OF A NW MID LVL
FLOW TO CWA TNGT PERHAPS SHIFTING THICKER MID CLOUDS TO W OF CWA.
LOW CLOUDS WL PROBABLY ENTER NERN ZONES LATE TNGT...AND COULD
POSSIBLY INCREASE ACROSS NERN 1/2 AT LEAST ON WED. MADE LTL
CHANGES TO TEMPS TNGT/WED.
WARM ADVCTN INCREASES ACROSS THE CWA LATE WED NGT INTO THU BUT BASED
ON 12Z GFS/NAM/ECMWF CUT BACK ON POPS SRN CWA THURSDAY. WEAK MID
LVL CIRCULATION TIED INTO NRN STREAM WAVE DOESN/T SAG INTO NRN
ZONES TILL CLOSER TO 00Z FRI. HOWEVER...GEM DVLPD PCPN IN 06Z-18Z
PD AND THUS LEFT IN MENTION FOR CONTINUITY SAKE NWRN ZONES LATE
WED NGT AND DID/T REMOVE ENTIRELY SRN ZONES THU MORNING. LOOKS
LIKE BEST SHOT OF SNOW WILL BE THU NGT AS THIS WEAK MID LVL WAVE
DRIVES SOME CONVERGENCE/WEAK WARM ADVCTN ALOFT GENERATED PCPN.
FAVORED LOCATION ACCORDING TO OPERATIONAL MODELS WOULD BE NERN
NEBR/WRN IA WHICH ALSO HAD SREF SUPPORT. THUS INCREASED POPS INTO
CATEGORICAL RANGE NERN 1/3 THU NGT. FORECAST SOUNDINGS FM GFS
FORECAST A MIX SRN CWA THU...OTHERS SUGGESTED JUST SNOW SO ATTM
LEFT PCPN TYPE SNOW ONLY. STORM TOTAL QPF AMOUNTS FM 12Z
NAM/GFS/ECMWF/GEM WERE ALL ROUGHLY IN 0.3-0.5 RANGE WITH HIGHEST
AMOUNTS GENERALLY IN NERN CWA. WINDS STILL DON/T LOOK EXCESSIVELY
STRONG AND NRN STREAM SEEMS PROGRESSIVE SO BARRING A SHIFT NWD TO
SRN STREAM SYSTEM...EVENT APPEARS LOW END ADVSRY ATTM. KEPT SMALLISH
DIURNAL RANGE IN TEMPS THU TO ACCOUNT FOR CLOUDS/PCPN.
STRONGER JET DIGGING SEWD IN NRN STREAM SHOULD SHUT PCPN OFF/KICK
OUT SRN STREAM SYSTEM FAIRLY QUICKLY FRI SO LINGERING PCPN COULD
BE MORE IN MORNING PD...BUT DID RAISE POPS A BIT ERN ZONES. KEPT
DIURNAL TEMP RANGE ON TIGHT SIDE FRI AS WELL BECAUSE OF LINGERING
CLOUDS/COOL ADVCTN IN AFTN.
.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY.
MAINLY QUIET WEATHER IS INDICATED AFTER THE PRE-CHRISTMAS SYSTEM
MOVES THROUGH. PHASING SYSTEM WILL RESULT IN A DEEP ERN US UPPER
LOW...WITH ANOTHER LOW IN THE GULF OF ALASKA AND STRONG RIDGING
BETWEEN OVER THE ROCKIES/CENTRAL US. CWA WILL BE UNDER THE
INFLUENCE OF NWRLY FLOW ON SATURDAY/SUNDAY...WHICH SHOULD KEEP SOME
CLOUDS AROUND AND ALSO WILL CHANNEL COLD AIR DOWN FROM CANADA.
WOULD NOT RULE OUT A FEW FLURRIES IN THAT TIME...BUT FORCING IS FAR
TOO WEAK TO TRY TO PIN DOWN THIS FAR OUT. DID LOWER MIN TEMP
FORECAST FOR SUNDAY MORNING AS CLOUDS MOVE AWAY AND SURFACE HIGH
MOVES OVERHEAD...PARTICULARLY IN THE NERN CWA WHERE THE POTENTIAL
FOR FRESHLY ACCUMULATED SNOW IS HIGHEST. OTHERWISE...TEMPS WILL
BEGIN TO MODERATE INTO EARLY NEXT WEEK AS THE UPPER RIDGE PROGRESSES
EASTWARD AND WARM AIR ADVECTION BEGINS. THERE IS SOME HINT OF A
MID-WEEK SYSTEM AS PATTERN BREAKS DOWN...BUT WITH SUBSTANTIAL
UNCERTAINTY...WILL KEEP LATE PERIODS DRY.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
VFR CONDITIONS ARE EXPECTED ACROSS THE TAF SITES THRU THE PD WITH A
FEW MID CLOUDS PASSING ACROSS THE SITES. HIGH PRESSURE WILL BE OVER
THE REGION TONIGHT WITH FAIRLY LIGHT NORTH SFC WINDS. A STRATUS DECK
CURRENTLY OVER THE EASTERN DAKOTAS AND MINNESOTA COULD SLIDE SOUTH
ACROSS KOFK AND KOMA DURING THE EARLY MORNING HOURS. DID LEAVE A
SCT015 LAYER IN AT KOFK BUT COULD APPROACH KOMA AS WELL AND BECOME
BKN TO OVC AT SOME POINT.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
CHERMOK/MAYES/KERN