FXUS66 KPQR 241056
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
255 AM PST THU DEC 24 2009

.SYNOPSIS...COOL DRY OFFSHORE FLOW FOR REST OF THE WEEK...AS STORMS 
HOLD UP OVER THE N PAC. WILL SEE FOGGY WEATHER IN THE CENTRAL AND 
SOUTH WILLAMETTE VALLEY NEXT SEVERAL DAYS...BUT EAST WINDS WILL KEEP 
OTHER AREAS PARTLY TO MOSTLY SUNNY. 

&&

.SHORT TERM...FOG AND LOW CLOUDS SHROUDING MOST OF THE INTERIOR
LOWLANDS THIS MORNING. A DENSE FOG ADVISORY WAS ISSUED FOR THE SAME
AREA...BUT AT THIS TIME ONLY THE LOWER COLUMBIA AND THE
PORTLAND/VANCOUVER METRO AREA MEET CRITERIA. THE REMAINDER OF THE
WILLAMETTE VALLEY HAS MOSTLY LOW STRATUS AT 2 AM BUT STILL EXPECT
INCREASE IN DENSE FOG THIS MORNING.   FOR THE REMAINDER OF THE
AREA...SHALLOW INVERSION KEEPING CLOUDS IN THE VALLEYS WITH SLIGHTLY
WARMER TEMPERATURES IN THE MOUNTAINS. FOG IN THE WIND SHELTERED
VALLEYS INCLUDING MUCH OF THE WILLAMETTE VALLEY WILL BE THE MAIN 
FORECAST CHALLENGE FOR THE REMAINDER OF THE WEEK.  DUE TO INVERSIONS
AND LIGHTER WINDS...WILL HAVE SOME PROBLEM MIXING OUT AIR MASS IN
LOWER ELEVATIONS TO NORTH OF VANCOUVER AND SOUTH OF SALEM FOR NEXT
SEVERAL DAYS. IN COORDINATION WITH SEATTLE AND OTHER GOVT AGENCIES
AIR STAGNATION ADVISORIES ARE IN EFFECT FOR NORTHERN CLARK COUNTY
AND COWLITZ VALLEY AS WELL AS THE CENTRAL AND SOUTHERN WILLAMETTE
VALLEY THROUGH SAT.

FOR AREAS NEAR AND THROUGH THE COLUMBIA GORGE EASTERLY WIND WILL BE
ON THE INCREASE TODAY. SURFACE HIGH PRES SLIDING INTO EASTERN OREGON
AND WASHINGTON FROM B.C. EAST TO WEST GRADIENT INCREASING WITH THE
KPDX-KDLS GRADIENT AT -3.7 MB AND STEADILY INCREASING. SHOULD SEE
ABOUT DOUBLE THAT GRADIENT LATE THIS AFTERNOON.  WINDS WILL PICK UP
MORE RAPIDLY THIS MORNING AS A STRONG OFFSHORE PRES GRADIENT SETS UP
ALONG THE CASCADES. SUSTAINED WINDS WILL LIKELY PEAK OUT AROUND 35
MPH WITH GUSTS TO 45 TO 50 MPH IN THE WINDIEST LOCATIONS SUCH AS
ROOSTER ROCK. EAST WINDS WILL DIMINISH THIS WEEKEND.

.LONG TERM...MODELS AGREE THAT A PERSISTENT UPPER LEVEL RIDGE WILL 
BREAK DOWN SOMETIME SUN AS A SYSTEM APPROACHES THE REGION. 
HOWEVER...MODELS DO DISAGREE ON THE STRENGTH OF THIS SYSTEM. GFS 
QUICKLY PUSHES THE SYSTEM ACROSS THE PAC NW FOLLOWED BY SEVERAL 
SYSTEMS NEXT WEEK. ECMWF SHOWS THIS PARTICULAR SYSTEM IMPACTING THE 
AREA THROUGH MON NIGHT. EITHER WAY...HAVE KEPT POPS SLIGHTLY BELOW 
CLIMATOLOGY GIVEN MODEL INCONSISTENCIES. EXPECT PRECIP THROUGH THE 
REMAINDER OF NEXT WEEK. LRAMIREZ
&&

.AVIATION...LIFR AT ALL VALLEY TAF SITES. KTTD-KDLS GRADIENT
BEGINNING TO INCREASE AT -4.4 MB. THIS SHOULD ALLOW EAST WIND TO
DEVELOP NEAR KTTD AROUND 12Z AND CLEAR THEM OUT. OFFSHORE
GRADIENT TODAY SHOULD BE ENOUGH TO REACH WEST PORTIONS OF THE NORTH
WILLAMETTE VALLEY...LIKE KHIO. WILL MAINTAIN LIFR AT KHIO THROUGH
THU MORNING THEN CLEAR IT OUT RATHER QUICKLY AS NE TO E WIND
DEVELOPS. DOWN THE VALLEY WILL BE SLOW TO CLEAR OUT IF THEY DO...
AND EXPECT SOME REDEVELOPMENT OF LIFR CONDITIONS TONIGHT. COAST
LOOKS VFR AS EAST BREEZES ARE PICKING UP.

KPDX AND APPROACHES...TOUGH FORECAST. MAIN FORECAST PROBLEM WILL BE 
ONSET OF EAST WINDS. WINDS LOOK TO PICK UP AROUND KTTD AROUND 12Z
OR SHORTLY THEREAFTER. EXPECT KPDX TO IMPROVE FROM THE CURRENT
LIFR BETWEEN 14Z AND 16Z. WILL NOT HAVE TO WORRY ABOUT FOG
DEVELOPMENT TONIGHT AS THE OFFSHORE LOW LEVEL FLOW CONTINUES.
TOLLESON
&&

.MARINE...SEAS BEGINNING TO COME UP TO 10 FT EARLY THIS MORNING IN
THE OUTER WATERS FROM OFFSHORE SWELL...AND THIS WILL WORK ITS WAY
INTO THE INNER WATERS LATER THIS MORNING. SEAS MAY EDGE DOWN
FRIDAY BUT THEN ANOTHER WESTERLY SWELL TRAIN COMES IN FRIDAY NIGHT
AND PEAKS IN THE MID TEENS OR SO OVER THE WEEKEND. OFFSHORE WIND
PATTERN IS KICKING IN THIS MORNING...AND WILL HAVE SOME BREEZY
CONDITIONS NEAR COASTAL GAPS TODAY. WINDS LOOK TO REACH SMALL
CRAFT ADVISORY LEVELS TONIGHT INTO THE WEEKEND AS A SYSTEM IS
OFFSHORE AND THE OFFSHORE INLAND WINDS CONTINUE AND INCREASE SOME.
TOLLESON
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...DENSE FOG ADVISORY UNTIL 10 AM PST THIS MORNING FOR CENTRAL 
     WILLAMETTE VALLEY-GREATER PORTLAND METRO AREA-LOWER 
     COLUMBIA-SOUTH WILLAMETTE VALLEY.

     AIR STAGNATION ADVISORY UNTIL 6 PM PST SATURDAY FOR CENTRAL 
     WILLAMETTE VALLEY-SOUTH WILLAMETTE VALLEY.

WA...AIR STAGNATION ADVISORY UNTIL 6 PM PST SATURDAY FOR GREATER 
     VANCOUVER AREA-I-5 CORRIDOR IN COWLITZ COUNTY.

     DENSE FOG ADVISORY UNTIL 10 AM PST THIS MORNING FOR GREATER 
     VANCOUVER AREA-I-5 CORRIDOR IN COWLITZ COUNTY.

PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 7 PM THIS EVENING TO 10 PM 
     PST SATURDAY FOR COASTAL COASTAL WATERS FROM CAPE SHOALWATER WA
     TO CASCADE HEAD OR

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST FRIDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR FROM
     10 NM TO 60 NM OFFSHORE

     SMALL CRAFT ADVISORY FOR WINDS FROM 4 AM FRIDAY TO 10 PM PST
     SATURDAY FOR COASTAL WATERS FROM FROM CASCADE HEAD OR TO
     FLORENCE OR FROM 10 NM TO 60 NM OFFSHORE.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 7 AM THIS MORNING 
     TO 10 PM PST FRIDAY FOR COASTAL WATERS FROM CAPE SHOALWATER WA
     TO FLORENCE OR OUT 10 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 7 AM
     THIS MORNING TO 4 AM PST FRIDAY.

&&

$$

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.