FXUS66 KPQR 262235
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
234 PM PST SAT DEC 26 2009

.SYNOPSIS...COOL OFFSHORE FLOW WILL CONTINUE OVER THE PACIFIC
NORTHWEST THROUGH THE WEEKEND HOWEVER EAST WINDS WILL GRADUALLY
WEAKEN TONIGHT AND SUNDAY. A VERY WEAK FRONT WILL LIFT UP FROM THE
SOUTH ON THE SUNDAY REACHING THE CENTRAL OREGON COAST SOUTHERN
WILLAMETTE VALLEY SUNDAY MORNING THEN CONTINUING FURTHER NORTH IN THE
AFTERNOON AND EVENING. PRECIPITATION WITH THIS FRONT WILL BE LIGHT
AND SPOTTY IF IT DOES OCCUR AT ALL. HOWEVER IT DOES HAVE THE
POTENTIAL TO INITIALLY FALL AS LIGHT FREEZING RAIN OR SNOW FLURRIES
IN LOCATIONS WITH ADEQUATE COLD AIR TRAPPED UNDER THE LOW LEVEL
INVERSION.

&&

.SHORT TERM...THE OFFSHORE PRESSURE GRADIENT THIS AFTERNOON BETWEEN
THE DALLES AND PORTLAND IS DOWN SLIGHTLY TO AROUND 9.5 MB BUT PLENTY
STRONG TO KEEP COLD EAST WINDS BLOWING OUT OF THE WESTERN GORGE AND
ACROSS MUCH OF THE EASTERN PORTLAND AND VANCOUVER METRO AREA. THE
OFFSHORE GRADIENT WILL CONTINUE NEAR ITS CURRENT STRENGTH THIS
EVENING THEN WEAKEN A BIT TONIGHT AND SUNDAY.  

THE FRONTAL SYSTEM OFFSHORE THAT WILL LIFT NORTH OVER THE AREA LOOKS
RATHER UNIMPRESSIVE BOTH ON THE SATELLITE IMAGERY AND MODELS HOWEVER
WITH THE COLD AIR TRAPPED AT LOWER ELEVATIONS ANY PRECIPITATION
THAT DOES FALL OUT OF IT HAS THE CHANCE OF STARTING OUT MIXED WITH
LIGHT FREEZING RAIN. GIVEN THE TIMING OF THE ONSET OF THE
PRECIPITATION IN THE MORNING THE SOUTH AND CENTRAL WILLAMETTE VALLEY
HAVE THE BEST ODDS OF SEEING SOME LIGHT FREEZING RAIN BUT CONFIDENCE
IS STILL TOO LOW IN HAVING ENOUGH PRECIPITATION WITH THE EXTREMELY
DRY AIR MASS AND WARM TEMPERATURES ALOFT TO ISSUE AN ADVISORY AT THIS
POINT. FURTHER NORTH THE PRECIPITATION CHANCES WILL DROP OFF QUICKLY
AS THE FRONT FALLS APART AND DOES NOT START UNTIL THE AFTERNOON WHEN
THE TEMPERATURES ARE WARMER...SO WHAT DOES FALL IS LIKELY TO BE RAIN.
 IF PRECIPITATION DOES MAKE IT FAR ENOUGH NORTH TO REACH THE GORGE 
SUNDAY NIGHT THERE IS A POSSIBILITY OF IT BEING A WINTERY MIX BUT 
ONLY A SLIGHT CHANCE OF IT BEING MEASURABLE. RUTHFORD

.LONG TERM...EXPECT A MORE ACTIVE AND WET WEATHER PATTERN TO BEGIN 
EARLY NEXT WEEK. A SHORTWAVE APPROACHES THE FORECAST AREA FROM OVER 
THE PACIFIC LATE TUE INTO WED. CURRENT MODEL RUNS ARE IN GOOD 
AGREEMENT ON BOTH THE TIMING AND STRENGTH OF THIS SYSTEM...BRINGING 
WARMER PRECIP TO THE AREA BY EARLY WED. SHOWERS SEEM TO LINGER 
THROUGH THU MORNING BEFORE THE NEXT SYSTEM APPROACHES. MODEL DETAILS 
REMAIN INCONSISTENT FOR THE END OF THE WEEK. NEVERTHELESS...EXPECT 
CONTINUED WET WEATHER FOR THE LATTER PORTION OF NEXT WEEK. BROWN

&&

.AVIATION...OFFSHORE PATTERN PERSISTS. KTTD-KDLS GRADIENT AT -9.4 MB 
AT 21Z...WHICH SUPPORTS GUSTS OF 30-35 KT AT KTTD. NAM-12 STILL 
UNDER-DOING THE GRADIENT. LITTLE CHANGE FOR THE 00Z TAFS. NAM SHOWS 
THE GRADIENT EASING TO AROUND 6 MB BY 15Z SUN...BUT STILL THINK THAT 
IT WILL BE HIGHER. GAP WIND CONTINUES AT THE COAST THIS AFTERNOON... 
BUT IT TOO WILL DROP OFF SOME SUN. KEUG FINALLY GOT OUT OF THE LIFR 
THIS AFTERNOON. EXPECT FOG AND LOW CLOUDS TO RETURN THIS EVENING AND 
TONIGHT...BUT CONDITIONS MAY NOT BE QUITE SO BAD. HIGH CLOUDS FROM A 
WEAKENING FRONTAL SYSTEM WILL SPREAD OVER THE SOUTH PART OF THE 
FORECAST AREA TONIGHT. NAM DOES NOT BRING ANY PRECIP TO THE FORECAST 
AREA SUNDAY WHILE THE GFS SPREADS A THIN BAND ALL THE WAY UP TO THE 
GORGE. BELIEVE THE GFS IS OVERDONE. KEUG MAY GET SOME LIGHT LATE SUN 
MORNING. IF ANYTHING OCCURS IT COULD IN THE FORM OF -FZRA.  

.KPDX AND APPROACHES...VFR CONDITIONS THROUGH 00Z MON. MAIN ISSUE 
WILL BE POTENTIAL SEVERE TURBULENCE AND LLWS. CONDITIONS WILL BE 
ROUGH ON EASTERN APPROACHES WITH VERY STRONG WIND FUNNELING THROUGH 
THE GORGE BUT MUCH LOWER SPEEDS AWAY FROM THE GORGE. WIND EXPECTED 
TO SLOWLY EASE A BIT TONIGHT AND SUN. WEISHAAR
&&

.MARINE...SMALL CRAFT WIND CONTINUES THIS AFTERNOON...ESPECIALLY 
NEAR THE COASTAL GAPS. SEVERAL OBSERVATIONS SHOWING GUSTS UP TO 30 
KT. THE OFFSHORE PATTERN WILL START TO EASE TONIGHT AS A WEAKENING 
DEFORMATION ZONE LIFTS NORTH. THIS FRONTAL BOUNDARY OR DEFORMATION 
ZONE WILL SLOWLY DRIFT THROUGH THE SOUTH WATERS TONIGHT AND REACH 
THE NORTH WATERS SUN MORNING. A STRONGER SYSTEM IS EXPECTED TO MOVE 
THROUGH THE COASTAL WATERS TUE AND WILL LIKELY GIVE SMALL CRAFT WIND 
SPEEDS. MODELS SHOW MORE VARIANCE DAYS 5-7. POTENTIAL FOR A GALE 
EVENT THU OR FRI AND HAVE TRENDED TOWARD THAT FOR NOW. 

GWW AND ENP CONTINUE TO OVER-ESTIMATE THE SEAS. MODELS INDICATE 13 
TO 15 FT 00Z SUN...WHILE LATEST AVAILABLE BUOYS REPORTS SHOW 10-11 
FT. HAVE ADJUSTED SEAS DOWNWARD A COUPLE OF FEET IN THE SHORT-TERM. 
STILL LOOKING AT SEAS TO AROUND 15 FT BY SUN. SEAS WILL REMAIN ABOVE 
10 FT THROUGH AT LEAST 12Z TUE. WEISHAAR
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...AIR STAGNATION ADVISORY UNTIL 10 AM PST SUNDAY FOR CENTRAL 
     WILLAMETTE VALLEY-SOUTH WILLAMETTE VALLEY.

WA...AIR STAGNATION ADVISORY UNTIL 10 AM PST MONDAY FOR GREATER 
     VANCOUVER AREA-I-5 CORRIDOR IN COWLITZ COUNTY.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 4 AM PST MONDAY FOR COASTAL
     WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 AM PST TUESDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 10 PM 
     PST SUNDAY.

&&

$$

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.