FXUS66 KPQR 281627
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
826 AM PST SAT NOV 28 2009

.SYNOPSIS...AN UPPER LEVEL RIDGE WILL BUILD OVER THE FORECAST AREA
TODAY. HOWEVER...THE TAIL END OF A WARM FRONT WILL DRIFT ACROSS THE
NORTH ZONES THIS AFTERNOON AND TONIGHT...AND THEN LIFT TO THE NORTH
BY SUNDAY. THE UPPER RIDGE WILL STRENGTHEN SUNDAY AND SHOULD PERSIST
THROUGH MONDAY...WHICH WILL RESULT IN VALLEY INVERSIONS. 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...SATELLITE WATER VAPOR SHOWS THE UPPER RIDGE CONTINUING
TO BUILD NE OVER THE FORECAST AREA THIS MORNING. IR SATELLITE IMAGERY
AND SURFACE OBSERVATIONS SHOW WIDESPREAD STRATOCUMULUS CLOUDS OVER
THE REGION WHICH HAS ALLOWED JUST SOME PATCHY FOG THIS MORNING.
MODELS AND IR SATELLITE STILL SHOW A WARM-FRONTAL FEATURE OVER THE
EASTERN PAC WHICH WILL SLIDE ACROSS WESTERN WA AND EXTREME NW OREGON
LATER TODAY AND TONIGHT. WILL KEEP CHANCE TO SLIGHT CHANCE POPS IN
THE NORTHERN ZONES.

THE UPPER RIDGE STRENGTHENS SUN WHICH WILL PUSH RESIDUAL WARM FRONT
MOISTURE TO THE N. VERY LIGHT OFFSHORE SURFACE GRADIENTS SET UP SUN
AFTERNOON WITH SURFACE HIGH PRES CENTERED NEAR THE OREGON AND IDAHO
BORDER. THE OFFSHORE GRADIENTS PICK UP A BIT MORE SUN NIGHT INTO MON.
THIS FAVORS A VALLEY FOG PATTERN AS AN INVERSION SETS UP UNDER THE
RIDGE...BUT SHOULD SEE A LITTLE E WIND DEVELOP NEAR THE GORGE. RW

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...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...VFR CONDITIONS ACROSS REGION WITH 4K TO 5K CIGS. NOT 
MUCH CHANGE TODAY THROUGH THIS EVENING AS WEAK WARM FRONT PASSES TO 
OUR N. CLOUDS BREAK MORE TONIGHT AS LIGHT OFFSHORE FLOW DEVELOPS 
BRINGING POSSIBILITY OF FOG TO INLAND SITES AFTER 08Z. 

KPDX AND APPROACHES...VFR CLOUDS TO HOLD ACROSS KPDX OPS AREA 
THROUGH THIS EVENING. NO ADVERSE WEATHER IMPACTS EXPECTED THROUGH 
08Z.  ROCKEY.

&&

.MARINE...WINDS REMAIN UNDER 20 KT FOR NEXT SEVERAL DAYS. HOWEVER... 
SWELL FROM STORMS OVER THE N PAC ARE NOW ARRIVING. THIS WILL KEEP 
SEAS AROUND 10 TO 11 FT TODAY...THEN BUILD A BIT MORE TONIGHT AS 
LARGE SWELL ARRIVE. SEAS WILL REMAIN IN THE 12 TO 15 FT RANGE FOR 
SUN THROUGH TUE. 

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
WA/OR...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FOR COASTAL WATERS   
      FROM CAPE SHOALWATER TO FLORENCE THROUGH SUN.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS     
      FOR THIS AFTERNOON...AND AGAIN LATE TONIGHT THRU SUN.
      
&&

$$

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.