FXUS66 KPQR 290422
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
821 PM PST SAT NOV 28 2009

.SYNOPSIS...THE TAIL END OF A WARM FRONT WILL DRIFT ACROSS THE
NORTH ZONES TONIGHT...AND THEN LIFT TO THE NORTH ON SUNDAY. AN UPPER
RIDGE WILL STRENGTHEN OVER THE AREA SUNDAY AND SHOULD PERSIST
THROUGH MONDAY...WHICH WILL RESULT IN VALLEY INVERSIONS AND AREAS OF
FOG. ANOTHER SYSTEM WILL RIDE OVER THE RIDGE LATE 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 INVERSIONS AND VALLEY FOG PERSISTING.

&&

.SHORT TERM...FLAT RIDGE OVER THE FORECAST AREA THIS EVENING WITH A
WARM-FRONTAL FEATURE SLIDING ACROSS THE ERN PAC AND WRN WA. LATEST
SCAN OF METARS AND OTHER SURFACE OBS DATA INDICATE PRECIP REMAINS
CONFINED TO THE WA COAST. NWS PORTLAND DOPPLER RADAR NOT SHOWING ANY
APPRECIABLE RETURNS AT ALL AS OF 04Z. 00Z NAM RUN INDICATES THE
WARM-FRONTAL FEATURE WILL SAG A BIT MORE SOUTH BY ABOUT 06Z BUT
TRIMMED BACK ON POPS. NAM LOW-LEVEL MOISTURE PROGS SHOW 90 PCT RH AT
06Z OVER SW WA AND EXTREME NW OREGON AT THE 850...900...AND 925 MB
LEVELS. THIS SEEMS TO CORRELATE WELL WITH OBS. GENERALLY CIGS AT 030
IN SW WA AND N OREGON COAST...RISING TO ABOUT 045 IN THE NORTH AND
CENTRAL WILLAMETTE VALLEY. ALL IN ALL NOT LOOKING AT MUCH QPF IN SW
WA AND THE N OREGON COAST...GENERALLY A FEW HUNDREDTHS AT BEST. SOME
LIGHT OFFSHORE FLOW ALONG THE COAST SOUTH OF NEWPORT HELPING TO
MAINTAIN GENERALLY CLEAR SKIES THERE.  

THE UPPER RIDGE WILL STRENGTHEN SUN WHICH WILL PUSH ANY RESIDUAL WARM
FRONT MOISTURE TO THE N. VERY LIGHT OFFSHORE SURFACE GRADIENTS SET UP
LATE SUN AFTERNOON WITH SURFACE HIGH PRES CENTERED NEAR THE OREGON
AND IDAHO BORDER...AND INVERTED SURFACE TROUGH ALONG THE SOUTH OREGON
COAST. THE OFFSHORE GRADIENTS PICK UP A BIT SUN NIGHT
INTO MON. MIGHT SEE 3-4 MB OFFSHORE FROM KDLS-KTTD BY 12Z MON.
NOTHING SPECTACULAR BUT SHOULD GIVE GUSTS TO 30 MPH OR SO IN THE
WINDIEST SPOTS. EXPECT MORE VALLEY FOG SUN NIGHT AS INVERSIONS SET UP
UNDER THE RIDGE. MOST PRONE PLACES WILL BE WEST AND SOUTH PARTS OF
THE WILLAMETTE VALLEY. 

NEXT SYSTEM SCHEDULED TO FALL APART AS IT REACHES THE AREA LATE MON.
MAIN AFFECT WILL BE A SWITCH TO LOW-LEVEL ONSHORE FLOW MON AFTERNOON.
MINIMAL...IF ANY...POPS WITH THIS SYSTEM. SURFACE HIGH BUILDS OVER
ERN BC MON NIGHT...WHICH WILL START TO TURN THE LOW-LEVEL FLOW BACK
TO OFFSHORE. WEISHAAR 

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...THE UPPER
RIDGE IS LIKELY TO HOLD THROUGH MIDWEEK...ALTHOUGH THE ECMWF HAS A
WEAK UPPER LOW CUTTING UNDERNEATH THE RIDGE ON WED. THAT SOLUTION IS
NOT SUPPORTED BY GFS ENSEMBLES OR THE CANADIAN MODEL. BEGINNING ABOUT
THU THE VARIOUS MODEL ARE SHOWING LARGE VARIATIONS IN POSSIBLE
SOLUTIONS AS THE UPPER RIDGE POTENTIALLY RETROGRADES INTO THE PAC.
GFS ENSEMBLES HINT AT HIGHER POPS CENTERED AROUND FRI. WE HAVE ADDED
POPS IN THE THU THROUGH SAT PERIOD BUT KEPT THEM WELL BELOW CLIMO
UNTIL THERE IS BETTER CONSISTENCY IN MODEL SOLUTIONS. RW

&&

.AVIATION...OVERALL CONDITIONS SLOW TO CHANGE. WITH THE EXCEPTION OF 
MVFR CEILINGS ALONG THE NORTH COAST WE STILL HAVE VFR CONDITIONS 
ACROSS THE REGION. CLOUDS SHOULD BREAK UP MORE TONIGHT AS LIGHT 
OFFSHORE FLOW DEVELOPS BRINGING THE POSSIBILITY OF FOG TO INLAND 
SITES AFTER 08Z. HOWEVER...THE BEST CHANCE OF FOG WILL BE FROM KSLE 
SOUTHWARD. FEEL ONSHORE FLOW ACROSS NW PART OF THE AREA WILL KEEP 
PLENTY OF CLOUDS IN THE KAST TO KPDX AREA. THIS WILL LIMIT FOG TO BE 
VERY PATCHY AT BEST.  

KPDX AND APPROACHES...VFR CLOUDS TO HOLD ACROSS KPDX OPS AREA 
THROUGH THIS EVENING. NO ADVERSE WEATHER IMPACTS EXPECTED THROUGH 
15Z.
&&

.MARINE...WINDS REMAIN UNDER 20 KT FOR THE NEXT SEVERAL DAYS. SWELL 
GENERATED FROM AFAR HAS ARRIVED. THIS SWELL WILL VARY IN HEIGHT FROM 
TIME TO TIME...BUT GENERALLY REMAIN IN THE 12 TO 15 FT RANGE THRU 
TUE. LARGEST WAVES WILL BE ACROSS THE NORTHERN AND OUTER COASTAL 
WATERS.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
WA/OR...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FOR COASTAL WATERS   
  FROM CAPE SHOALWATER TO FLORENCE THROUGH SUN EVENING.      
  
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR CONDITIONS 
  THROUGH SUN 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.