FXUS66 KPQR 272144
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
143 PM PST FRI NOV 27 2009

.SYNOPSIS...THE WET SYSTEM FROM THANKSGIVING HAS FINALLY MOVED EAST
OF THE CASCADES THIS AFTERNOON...BRINGING DRYING WEATHER AND EVEN
SOME SUN BREAKS. AN UPPER LEVEL RIDGE WILL PUSH IN TONIGHT AND
SATURDAY...THOUGH A WARM FRONT CROSSING OVER THE RIDGE WILL BRUSH THE
NORTHWEST PARTS OF OUR FORECAST AREA LATER TONIGHT AND
SATURDAY...LIFTING NORTH BY SUNDAY. WITH THE BUILDING...AN INVERSION
WILL DEVELOP WITH INCREASING NIGHT AND MORNING VALLEY FOG. ANOTHER
SYSTEM WILL RIDE OVER THE RIDGE MONDAY AND MONDAY NIGHT...BUT AT MOST
BRUSH THE FAR NORTH PART OF OUR FORECAST AREA. OTHERWISE...THE UPPER
RIDGE WILL CONTINUE THROUGH MOST OF NEXT WEEK WITH AN INVERSION AND
VALLEY FOG PERSISTING.
&&

.SHORT TERM...THE SYSTEM FROM THANKSGIVING HAS FINALLY MOVED EAST OF
THE CASCADES THIS AFTERNOON. CLOUDS ARE STILL SOLIDLY UP AGAINST THE
CASCADES THOUGH NOT MUCH IS SHOWING UP ON THE NATIONAL WEATHER
SERVICE DOPPLER WEATHER RADAR. SUNSHINE HAS BROKEN OUT ACROSS MUCH OF
THE INTERIOR VALLEY AREA. STILL A FAIR AMOUNT OF BROKEN CLOUDS OFF
THE COAST THAT MAY NOT ALLOW MUCH CLEARING ON THE COAST.

WITH WET GROUND...SHOULD SEE SOME FOG DEVELOP OVERNIGHT AS AN UPPER
RIDGE BUILDS INTO THE PACIFIC NORTHWEST. HOWEVER...THE MODELS STILL
SHOW THE FAR NORTHWEST PART OF OUR FORECAST AREA BEING BRUSHED WITH
SOME WARM FRONTAL PRECIPITATION LATER TONIGHT THROUGH SATURDAY NIGHT.
IT IS LOOKING MORE LIKE JUST THE FAR NORTH...SO HAVE EASED BACK A BIT
ON THE SOUTHERN EXTENT OF ANY PRECIPITATION. OF MORE IMPORTANCE WILL
BE THE LOW CLOUDS AND FOG THAT DEVELOP IN THE LOWLANDS UNDER THE
BUILDING 500 MB RIDGE DUE TO THE DEVELOPING INVERSION. THE GRADIENTS
ARE RATHER LIGHT...SO THE FOG THAT DEVELOPS WILL LIKELY BE SLOW TO
CLEAR SATURDAY AFTERNOON.

WE DEVELOP A BIT OF OFFSHORE FLOW SUNDAY AFTER THE MORNING FOG.
SHOULD SEE BETTER CLEARING SUNDAY AFTERNOON ESPECIALLY AROUND THE
PORTLAND AREA AND ALONG THE COAST. AREAS AWAY FROM THE GORGE MAY
STILL BE A BIT SLOW TO CLEAR.

THE MODELS STILL LOOK RATHER DRY ON MONDAY...WITH THE PREVIOUSLY
ADVERTISED SYSTEM SPLITTING. THE NORTH PART THAT TRIES TO MOVE INTO
THE PACIFIC NORTHWEST IS QUITE WEAK. HAVE BACK OFF ON ANY POPS FOR
MONDAY WITH THE MAIN FORECAST PROBLEM AGAIN BEING LOW ELEVATION FOG.

THE DEVELOPING INVERSION WILL CAUSE FOOTHILL AREAS TO BE A BIT WARMER
THAN PREVIOUSLY FORECAST AND HAVE BUMPED THOSE UP. TOLLESON

.LONG TERM...A BRIEF SHORTWAVE PASSES TO THE NORTH OF THE PAC NW MON 
AFTERNOON. NEWEST MODEL RUNS HAVE AMPLIFIED A RIDGE OVER THE 
REGION...LOWERING THE IMPACT THIS DISTURBANCE HAS FOR THE FORECAST 
AREA. THIS DISTURBANCE DOES LEVEL THE UPPER RIDGE AT THIS TIME...BUT 
ANTICIPATE DRY AND MOSTLY CLEAR CONDITIONS. A SYSTEM APPROACHES AND 
CAUSES DISAGREEMENT AMONG THE MODELS AROUND WED. PREVIOUS RUNS OF 
ECMWF/CANADIAN WERE MORE CONSERVATIVE...KEEPING THE SYSTEM STALLED 
OFFSHORE UNTIL THE WEEKEND. HOWEVER...THE 12Z ECMWF RUN SHOWS A 
DISTURBANCE BRINGING PRECIP OVER THE REGION BY EARLY THU. GFS BRINGS 
PLENTY OF PRECIP IN BY THU NIGHT...WHILE THE ECMWF HAS WEAK HIGH 
PRES HOLD BACK THE BULK OF THE SYSTEM. STILL AGREED MORE WITH THE 
00Z ECMWF/CANADIAN RUNS AND KEPT THE AREA DRY AFTER TUE AFTERNOON. 
WILL HAVE TO WATCH THE MODELS CONSISTENCY FOR THE TIMING AND 
STRENGTH OF THIS NEXT SYSTEM. LRAMIREZ
&&

.AVIATION...NICE EVENING FOR EVENING FLYING...WITH SCATTERED VFR 
CLOUDS. ALTHOUGH DECK OVER THE CASCADES WILL BE SLOWER TO DISSIPATE. 
OVERALL SHOULD SEE DECREASING CLOUDS THIS EVENING. ONSHORE NW FLOW 
WILL BRING SOME CHALLENGE TO TONIGHTS TAFS. NOT IDEAL FLOW FOR 
WIDESPREAD FOG...BUT WITH CLEARING SKIES AND LIGHT WINDS SHOULD 
EASILY SEE AREAS OF FOG FORMING AFTER 08Z...WITH BEST THREAT OVER 
THE INTERIOR. HOWEVER...WITH SEEMS TO BE REASONABLE AMOUNT OF CLOUDS 
OFFSHORE...WHICH MAY LIMIT FOG EXTENT ALONG THE COAST AND INTO THE 
KKLS TO KPDX CORRIDOR. AS RESULT...SOME AREAS THERE MAY ONLY SEE 
PATCHY FOG. FOR NOW...WILL TREND THAT DIRECTION...WITH MORE 
WIDESPREAD FOG S OF KHIO TO KUAO LINE AFTER THE 08Z-10Z TIMEFRAME. 
AND FOG THAT FORMS WILL PERSIST WELL INTO SAT AM...POSSIBLY LATER.

KPDX AND APPROACHES...VFR CONDITIONS THIS EVENING WITH LIGHT NWLY 
ONSHORE FLOW. EXPECT AREAS OF FOG TO FORM AROUND KPDX NEAR 09Z. 
LOOKS AS THOUGH MAY WIND UP WITH MORE IFR STATUS AFTER 11Z RATHER 
THAN IFR FOG...BUT THESE LOW CIGS WILL BE PERSISTENT THROUGH 18Z.  
&&

.MARINE...GRADIENTS WILL GRADUALLY RELAX THIS EVENING...WITH GUSTY
NW WINDS RELAXING LATER THIS EVENING. SEAS BIT SLOWER TO SUBSIDE. 
SEAS BRIEFLY DROP BELOW 10 FT LATE LATE TONIGHT...BUT WILL RISE ABOVE
10 FT AGAIN LATER SAT. EVEN THOUGH NO SIGNIFICANT WINDS ARE EXPECTED 
THIS WEEKEND AND EARLY NEXT WEEK...SEAS WILL REMAIN IN THE 12 TO 15 
FT RANGE FOR SUN THROUGH TUE. 
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
WA/OR...SMALL CRAFT ADVISORY FOR WINDS THIS EVENING FOR COASTAL
	    WATERS FROM CAPE SHOALWATER TO CASCADE HEAD.
	SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FOR COASTAL WATERS
	    FROM CAPE SHOALWATER TO FLORENCE THROUGH TONIGHT.
	SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS 
	    TONIGHT.

&&

$$

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.