609 
FXUS66 KPQR 212226
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
220 PM PST SAT NOV 21 2009


.SYNOPSIS...A STRONG PACIFIC FRONTAL SYSTEM IS APPROACHING THE COAST
THIS AFTERNOON WITH A WARM FRONT MOVING INLAND THIS AFTERNOON AND
EVENING...AND THE ASSOCIATED COLD FRONT QUICKLY FOLLOWING TONIGHT AS
A SURFACE LOW PRESSURE SYSTEM MOVES INLAND NEAR THE WA OREGON BORDER.
A WEAK RIDGE OF HIGH PRESSURE WILL FOLLOW SUN AFTERNOON AND
NIGHT...BEFORE THE NEXT FRONTAL SYSTEM ARRIVES MON. 
&&

.SHORT TERM...MODELS ARE STILL SHOWING DIFFERENCES IN TRACK OF THE
SURFACE LOW COMING IN TONIGHT. THE GENERAL CONSENSUS IS TO BRING IT
IN JUST NORTH OF THE WASHINGTON/OREGON BORDER. MODELS ARE IN BETTER
AGREEMENT ON THE UPPER FEATURES...WITH A STRONG SHORTWAVE MOVING
ACROSS THE FORECAST AREA TONIGHT...DIGGING TO THE ESE. TIMING OF THE
COLD FRONT IN ALL MODELS INDICATES FRONTAL PASSAGE ON THE COAST
AROUND MIDNIGHT TONIGHT. HAVE UPGRADED THE HIGH WIND WATCH FOR THE
ENTIRE COAST TO A HIGH WIND WARNING. WINDS INLAND LOOK GUSTY WITH AND
BEHIND THE FRONT AS THERE ARE STRONG PRESSURE RISES BEHIND THE
FRONT...WILL ISSUE AN ADVISORY FOR THE WILLAMETTE VALLEY..I-5
CORRIDOR AND THE LOWER COLUMBIA FOR TONIGHT AND EARLY SUNDAY MORNING
WITH THE AFTERNOON PACKAGE.

DOPPLER RADAR INDICATES THAT SHOWERS HAVE SIGNIFICANTLY DIMINISHED
OVER THE AREA WITH ONLY AN ISOLATED SHOWER OR TWO OVER THE SOUTH
WASHINGTON CASCADES AND HAVE ALREADY CANCELLED THE SNOW ADVISORY FOR
THE CASCADES. WILL CONTINUE  THE WINTER STORM WARNING FOR THE
CASCADES AS MOISTURE...STRENGTH OF THE FRONT AND THE POST FRONTAL
FLOW ALL FAVOR SIGNIFICANT SNOWFALL FOR LATER TONIGHT AND SUN.

A WEAK UPPER RIDGE WILL BUILD OVER THE FORECAST AREA SUNDAY NIGHT AND
MONDAY FOLLOWING THE FRONT. BEST CHANCES FOR PRECIPITATION MONDAY AND
TUESDAY WILL SHIFT N INTO WA WITH WARM FRONT OVERRUNNING. THE UPPER
RIDGE HOLDS COLD FRONT AT BAY UNTIL AFTER TUE NIGHT. LIKENS

.LONG TERM...WEAK HIGH PRES RIDGE OVER THE FORECAST AREA CONTINUES TO
PUSH ENERGY NORTH OF FORECAST AREA MID WEEK. IT MANAGES TO DELAY THE
ARRIVAL OF A SECOND SYSTEM THROUGH THUR. MODEL SOLUTIONS DIVERGE
TOWARD THE END OF THE WEEK AND HAVE LITTLE CONFIDENCE IN THEM. AT
THIS TIME WILL GO WITH CLIMATOLOGY UNTIL THERE IS SOME CONSISTENCY
BETWEEN THE MODELS..

&&

.AVIATION...PREDOMINATELY VFR WITH SCATTERED SHOWERS...WHICH MAY 
BRING VERY BRIEF MVFR CIGS. CONDITIONS REMAIN VFR THIS 
AFTERNOON...THOUGH WILL SEE INCREASING MVFR ALONG THE COAST AS WARM 
FRONT SWINGS ACROSS THE REGION. COLD FRONT TONIGHT WILL BRING 
INCREASING MVFR AFTER 04Z...AND INCREASING SOUTHERLY WINDS SOME OF 
WHICH MAY BE QUITE STRONG IN SOME AREAS. LOCATION OF STRONG WINDS 
WILL DEPEND ON WHERE THE LOW COMES INLAND. 

KPDX AND APPROACHES...VFR CONDITIONS THROUGH 05Z...THEN INCREASING 
MVFR CIGS AS COLD FRONT APPROACHES. WATCH FOR POTENTIAL OF LOW LEVEL 
WIND SHEAR BETWEEN 06Z AND 18Z TONIGHT AND TOMORROW MORNING AS WILL 
SEE INCREASING SOUTH WINDS ALOFT...BLOWING OVER THE LOW LEVEL 
EASTERLY FLOW COMING FROM GORGE. SOUTH TO SOUTHWEST WINDS MAY BE 
QUITE STRONG AROUND 12Z AS STRONG GRADIENT DEVELOPS OVER NORTH 
VALLEY AS LOW MOVES INLAND. WIND GUSTS NEAR 50 TO 55 MPH ARE 
POSSIBLE. WOLFE
&&

.MARINE...GALE FORCE SOUTH WINDS WILL STRENGTHEN TO STORM FORCE AS 
POTENT LOW MOVES OVER THE COASTAL WATERS. STORM WARNING FOR THE 
COASTAL WATERS FOR TONIGHT. WINDS TURN MORE W TO NW ON SUNDAY AND 
BEGIN EASING. SEAS TONIGHT LIKELY TO PEAK IN THE 20 TO 25 FT 
RANGE...BUT WILL DROP QUICKLY TO THE MID TEENS ON SUN. 
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
WA/OR...GALE WARNING FOR COASTAL WATERS FROM CAPE SHOALWATER TO 
     FLORENCE FOR THIS AFTERNOON.
STORM WARNING FOR COASTAL WATERS FROM CAPE SHOALWATER TO 
     FLORENCE FOR TONIGHT. 
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR CONDITIONS 
     THROUGH SUN.
WINTER STORM WARNING FOR THE S WA AND N AND CENTRAL OREGON
     CASCADES TONIGHT AND SUNDAY.
HIGH WIND WARNING FOR THE SOUTHERN WASHINGTON/NORTHERN AND   
    CENTRAL OREGON COAST TONIGHT.
WIND ADVISORY FOR THE WILLAMETTE VALLEY..THE LOWER 
     COLUMBIA..AND THE I-5 CORRIDOR FOR THIS EVENING THROUGH
     SUNDAY MORNING.
&&

$$

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.