FXUS66 KPQR 092231
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
231 PM PST WED DEC  9 2009

.SYNOPSIS...AN ARCTIC AIR MASS WILL CONTINUE THROUGH THE END OF THE
WEEK. THE BRUNT OF A PACIFIC SYSTEM IS EXPECTED TO MOVE INTO
CALIFORNIA LATE FRIDAY...WITH SOME PRECIPITATION LIKELY MOVING UP
INTO THE REGION FRIDAY NIGHT AND SATURDAY. THIS PRECIPITATION MAY
START OUT AS A LIGHT WINTRY MIX OVER INLAND AREAS...WITH A WINTRY MIX
POSSIBLY LINGERING INTO SATURDAY NIGHT NEAR THE COLUMBIA GORGE. A
LARGER WARMER SYSTEM IS EXPECTED FOR EARLY NEXT WEEK.

&&

.SHORT TERM...GENERALLY A CLEAR AND COLD FORECAST FOR THIS WEEK. EAST
WINDS SHOULD BE CONFINED TO THE WESTERN GORGE AND WILL BE FAIRLY
LIGHT BY GORGE STANDARDS. MAXIMUM TEMPS WILL AGAIN BE COLD TODAY AND
THU WITH ONLY BRIEF WARMING NEAR OR SLIGHTLY ABOVE FREEZING INLAND
AREAS. THE LACK OF WIND WILL ALLOW FOR SOME GOOD COOLING AGAIN
TONIGHT. 

THE COLD N-NW FLOW ALOFT OVER THE NW US WILL MOVE NE THU
NIGHT AND FRI ALLOWING THE AIR MASS ALOFT TO BEGIN SOME WARMING.
HOWEVER THE VALLEYS WILL BE SLOW TO SCOUR OUT. THE SOUTHERN JET
STREAM PUSHING SYSTEMS INTO CA WILL BEGIN TO LIFT N A BIT ON FRI FOR
THE POSSIBILITY OF SOME MOISTURE WITH A WARMER AIR MASS LIFTING INTO
OREGON. WITH COLD AIR IN PLACE THE ONSET OF ANY PRECIPITATION WILL
MOST LIKELY BE IN THE FORM OF FREEZING RAIN AND OR SNOW THOUGH AT THE
MOMENT ANY ACCUMULATION WILL BE ON THE LIGHT SIDE. ONE CAVEAT IS THE
00Z WRF GFS DOES BRING IN THE PRECIP TO THE SOUTH VALLEY AS EARLY AS
MIDDAY FRIDAY. THIS MODEL DOES SHOW WARMING THOUGH LIKELY BELIEVE
THIS IS TOO QUICK AND LIKELY ARTIFICIAL.

ON THE OTHER HAND...THE ECMWF TAKES THE LOW INTO CALIFORNIA AND
LEAVES THE PAC NW HIGH AND DRY BUT KEEPS US COOL. THIS IS BEGINNING
TO BECOME THE FAVORED SOLUTION ESPECIALLY SINCE THE JET IS DRIVING 
INTO SOUTHERN CALIFORNIA AND THERE DOES NOT SEEM TO BE MUCH SUPPORT 
TO MOVE A LOW UP THE COAST AS THE GFS SUGGESTS. FURTHER GFS 
ENSEMBLES DO NOT INDICATE MUCH OF A NORTHWARD PROGRESSION OF THE 
PRECIP...WITH ONLY A FEW MEMBERS PULLING THE PRECIP AS FAR NORTH AS 
OUR FORECAST AREA. REGARDLESS THERE IS STILL A LOT OF UNCERTAINTY 
ESPECIALLY CONSIDERING THE WIDE ARRAY OF SYSTEM TRACKS...BUT THE 
PROGRESSION OF EVENTS WILL BE INTERESTING. KEEP AN EYE OUT ON THE 
LOCAL FORECASTS AS THE SITUATION COULD TURN SOUR IF THE GFS IS 
ACCURATE. WOLFE

.LONG TERM...MODELS IN DECENT AGREEMENT INTO SUN...AS SURFACE LOW 
PASSES INLAND TO THE S OF FORECAST AREA. SOME MIXED PRECIPITATION 
INTO MAY CONTINUE IN THE N INTO SAT NIGHT OR SUN MORNING BEFORE FLOW 
TURNS ONSHORE. A BIT OF A BREAK IS POSSIBLE SUN INTO SUN NIGHT...BUT 
THEN MODELS DIVERGE SIGNIFICANTLY AFTER THAT. FOR NOW WILL LEAN 
TOWARDS THE ECMWF 12Z OPERATIONAL RUN WHICH HAS BEEN A LITTLE MORE 
CONSISTENT WITH PREVIOUS RUNS...AND IS SUPPORTED BY THE GFS ENSEMBLE 
MEAN. THIS INFERS HIGHER THAN CLIMATOLOGICAL POPS WITH SOMETHING 
APPROACHING NORMAL TEMPS. THE COLDER SOLUTION OF THE GFS OPERATIONAL 
RUN LOOKS INTERESTING...BUT FOR NOW APPEARS TO BE SOMETHING OF AN 
OUTLIER.

&&

.AVIATION...VFR CONDITIONS THROUGH THURSDAY. AIR MASS VERY DRY SO
DO NOT SEE MUCH THREAT OF CLOUDS OR FOG. 

KPDX AND APPROACHES...VFR CONDITIONS AND LIGHT EAST WINDS EXPECTED 
THROUGH THURSDAY. 

&&

.MARINE...SEAS RUNNING 2 TO 3 FT BELOW MODEL PREDICTIONS SO HAVE
ENDED SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS...AND ROUGH BAR. WINDS
REMAIN LIGHT TO LOCALLY MODERATE OFFSHORE THROUGH FRI. NEXT THREAT
FOR MARINE HAZARDS UNCERTAIN AS MODELS HAVING DIFFICULTY WITH
INCOMING WEATHER SYSTEM POSITIONS AND TIMING. HIGH END SMALL CRAFT
ADVISORY CONDITIONS BORDERING ON GALES POSSIBLE MONDAY.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...NONE.

&&

$$

MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.