FXUS66 KPQR 230447
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
847 PM PST TUE DEC 22 2009

.SYNOPSIS...DRY WEATHER WILL PREVAIL FROM TONIGHT THROUGH AT LEAST 
CHRISTMAS AS A STRONG UPPER LEVEL RIDGE BUILDS ALONG THE COAST. 
BRISK EAST WINDS WILL DEVELOP NEAR THE COLUMBIA RIVER GORGE 
WEDNESDAY NIGHT AND WILL LIKELY CONTINUE THROUGH THE WEEKEND AS THE 
RIDGE CONTINUES TO HOLD. THE NEXT CHANCE OF RAIN MAY HOLD OFF UNTIL 
EARLY NEXT WEEK.

&&

.SHORT TERM...THE FLOW ALOFT HAS SHIFTED TO THE NNW IN RESPONSE TO
THE STRENGTHENING OF AN UPPER LEVEL RIDGE JUST OFFSHORE. SKIES ARE
CLEARING RAPIDLY THIS EVENING WITH LOWS ALREADY NEAR OR A COUPLE
DEGREES BELOW FREEZING. BETWEEN THE CLEAR SKIES AND LIGHT WINDS
TONIGHT HAS THE POTENTIAL TO BE RATHER CHILLY.

THE RIDGE ALOFT WILL CONTINUE TO STRENGTHEN AND SHARPEN A BIT
TOMORROW THEN SHIFT EAST SO THAT ITS AXIS ALONG THE COAST BY THURSDAY
MORNING. IN RESPONSE OFFSHORE FLOW WILL DEVELOP WITH EAST WINDS
STRENGTHENING THROUGH THE COLUMBIA RIVER GORGE AND OTHER GAPS AND
PASSES IN THE CASCADES. EAST WINDS WILL INCREASE GRADUALLY THROUGH
THE DAY ON WEDNESDAY REACHING THE 15 TO 20 KT RANGE IN THE WESTERN
GORGE BY AFTERNOON.  WINDS WILL PICK UP MORE RAPIDLY WEDNESDAY NIGHT
AND THURSDAY AS A STRONG OFFSHORE  PRESSURE GRADIENT SETS UP ALONG
THE CASCADES.  SUSTAINED WINDS WILL LIKELY PEAK OUT AROUND 40 OR 45
KNOTS WITH GUSTS TO 50 OR 60 KNOTS IN THE WINDIEST LOCATIONS SUCH AS
ROOSTER ROCK. EAST WINDS WILL DIMINISH SATURDAY AND SUNDAY INTO THE
20 TO 30 KT RANGE.

ASIDE FROM THE INCREASING GAP WINDS...FOG IN THE WIND SHELTERED
VALLEYS INCLUDING MUCH OF THE WILLAMETTE VALLEY WILL BE THE MAIN
FORECAST CHALLENGE FOR THE REMAINDER OF THE WEEK. RUTHFORD

.LONG TERM...AN UPPER LEVEL RIDGE PERSISTS THROUGH THE FORECAST AREA 
THROUGH THE END OF THE WEEK. MODELS VARY SIGNIFICANTLY WITH THE 
BREAKDOWN OF THE RIDGE NEXT WEEKEND AND THE ARRIVAL OF ANY 
SUBSEQUENT SYSTEMS...AS SHOWN BY INCREASING ENSEMBLE SPREADS. EXPECT 
A SLIGHT CHANCE OF PRECIP SOMETIME LATE SAT/EARLY SUN THROUGH EARLY 
NEXT WEEK...WITH A STRONG SYSTEM APPROACHING THE REGION BY MID NEXT 
WEEK. HAVE KEPT POPS SLIGHTLY BELOW CLIMATOLOGY GIVEN THE CONTINUED 
INFLUENCE OF THE RIDGE AND MODEL INCONSISTENCIES. RAMIREZ

&&

.AVIATION...AIR MASS STABILIZING TONIGHT...WILL SEE LARGE AREAS OF
CLEARING COUPLED WITH LIGHT WIND WILL GIVE A GOOD THREAT OF FOG AND
LOW CLOUDS. AT THIS TIME...WILL SEE AREAS OF FOG FORMING OVER
INLAND AREAS AFTER 08Z...AND PERSISTING WELL INTO WED AM.

KPDX AND APPROACHES...FOG OR IFR STRATUS FORMING AROUND KPDX OPS
AREA BETWEEN 08Z AND 11Z TONIGHT. SUSPECT WILL WIND UP WITH MORE
LOW STRATUS AT KPDX THAN FOG.

&&

.MARINE...NO MAJOR CHANGES. HIGH PRES OFFSHORE WILL SLOWLY SHIFT 
INLAND OVER PAC NW OVER THE NEXT FEW DAYS. THIS WILL BRING LIGHT
OFFSHORE
WINDS LATER TONIGHT AND WED. SEAS OF 8 TO 10 FT. NO MAJOR WEATHER
EXPECTED FROM WED THROUGH EARLY SAT AS HIGH PRES OVER PAC NW KEEPS
LIGHT OFFSHORE WINDS CONTINUING.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 9 PM PST THIS 
     EVENING FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE
     OR OUT 60 NM.

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

&&

$$

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.