FXUS66 KPQR 242232
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
230 PM 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...SEEMS LIKE A BROKEN RECORD. EAST WINDS BLOWING NICELY 
OVER THE HIGHER TERRAIN...AND THROUGH THE W COLUMBIA GORGE. BUT FOG 
AND STRATUS STILL HUGGING THE INTERIOR LOWLANDS THANKS TO THE 
INVERSION AROUND 1500 TO 2000 FT. SUNNY ON THE COAST AND OVER THE 
HIGHER TERRAIN...WHERE TEMPS ARE IN THE UPPER 40S TO UPPER 50S. EVEN 
A FEW TEMPERATURES OF 60 TO 61 REPORTED IN THE CASCADE FOOTHILLS. 
DIFFERENT STORY UNDER THE INVERSION WHERE CLOUDS AND FOG HAVE KEPT 
TEMPS IN THE LOWER TO MID 30S ACROSS MUCH OF THE INTERIOR LOWLANDS.

CROSS GORGE GRADIENT NOW ABOUT 7 MB WITH GUSTY EAST WINDS AT 
TROUTDALE. BUT DUE TO WEAK LEESIDE LOW THAT SITS NEAR THE FOOTHILLS 
OF THE CASCADES...WINDS STILL WEAK AND VARIABLE FURTHER WEST. AS 
RESULT...EAST WINDS HAVE BEEN DELAYED IN REACHING THE REST OF THE 
PORTLAND/VANCOUVER METRO. THE EAST WINDS BREAK THROUGH LATER THIS 
EVENING ACROSS THIS AREA. FURTHER AWAY...TO THE N VANCOUVER AND S OF 
SALEM...WINDS REMAIN LIGHT ENOUGH THAT FOG AND LOW CLOUDS WILL 
REFORM AGAIN LATER TONIGHT. 

DUE TO INVERSIONS AND LIGHTER WINDS BENEATH THEM...WILL HAVE SOME 
PROBLEM MIXING OUT AIR MASS IN LOWER ELEVATIONS TO N OF VANCOUVER 
AND S OF SALEM THROUGH SATURDAY. WILL CONTINUE AIR STAGNATION 
ADVISORIES IN THOSE AREAS...FOR ELEVATIONS BELOW ABOUT 1500 FEET. 

SATURDAY BEGINS TRANSITION PERIOD...AS LOW BEGINS TO MOVE UP ALONG 
THE OREGON COAST BRINGING RETURN TO LIGHT SOUTH TO SOUTHEAST FLOW.  
THIS LOW WILL BRING A BAND OF LIGHT PRECIP ACROSS THE REGION FROM S 
TO N LATER SAT NIGHT. HOWEVER...DUE TO CONTINUED MODERATE OFFSHORE 
FLOW...SEEMS ANY MOISTURE WILL BE EVAPORATED IN THE NORTH BEFORE IT 
CAN REACH THE GROUND. BEST THREAT OF RAIN...ALBEIT NOT GREAT...WILL 
BE ALONG THE COAST AND S OF SALEM SAT NIGHT. IF ANY MOISTURE CAN 
MOVE FURTHER N...COULD BE PROBLEMATIC DUE TO COLD TEMPS. MAY HAVE TO 
WATCH FOR POTENTIAL OF SOME VERY LIGHT FREEZING RAIN OR FLURRIES 
MAINLY IN THE COLUMBIA GORGE. MAY HAVE BETTER FEEL FOR THIS SCENARIO 
TOMORROW AND SATURDAY AS TIME DRAWS CLOSER TO THE EVENT.    ROCKEY.

.LONG TERM...MODELS CONTINUE TO BREAK DOWN A PERSISTENT UPPER LEVEL 
RIDGE THROUGH SUN AFTERNOON. PREVIOUSLY THOUGHT TO TRAVEL DIRECTLY 
TOWARDS THE PAC NW...A SYSTEM TRACKS TOWARDS NORTHERN CALIF. NOT 
LIKELY THE CWA WILL SEE ANY PRECIP WITH THIS PARTICULAR SYSTEM. GFS 
AND ECMWF DISAGREE ON A SECOND SYSTEM BY TUE. ECMWF IS FASTER...
HAVING THE ASSOCIATED COLD FRONT ARRIVE EARLY TUE. GFS HAS A RIDGE 
RETURN...PUSHING THIS UPPER LOW INTO THE REGION BY LATE WED. 
NEVERTHELESS...EXPECT WET WEATHER FOR THE REMAINDER OF NEXT WEEK. 
500MB TEMPS BY FRI LOOK A FEW DEGREES WARMER THAN THE PREVIOUS WEEK. 
RIGHT NOW...ANY PRECIP FOR LATE NEXT WEEK WILL PROBABLY BE RAIN. 
RAMIREZ
&&

.AVIATION...OFFSHORE LOW-LEVEL GRADIENT CONTINUES TO INCREASE THIS 
AFTERNOON...BUT NW TO N FLOW ABOVE THE INVERSION. LOW CLOUDS AND FOG 
ERODING FROM THE NORTHWEST PER VISIBLE IMAGERY. KSLE MAY GET TO 
LOW-END MVFR FOR A BIT THEN GO BACK DOWN. KEUG STUCK IN IFR TO LIFR 
AND WILL STAY THERE. LATEST PIREP INDICATED TOPS OVER KEUG AT 2K FT. 
NO PROBLEMS AT THE COAST. OFFSHORE SURFACE GRADIENT CHRISTMAS DAY 
WILL KEEP THINGS CLEAR AT KTTD AND KPDX.  

KPDX AND APPROACHES...KPDX FINALLY IMPROVED TO MVFR AT 2130Z. EAST 
WIND HAD NOT MADE IT THAT FAR WEST YET. THE KPDX-KTTD GRADIENT 
PEAKED AT 1.0 MB EARLIER IN THE AFTERNOON...BUT IS STARTING TO 
WEAKEN AS OF 22Z. EAST WIND SHOULD SURFACE AROUND 00Z FRI. MAY SEE 
FLUCTATIONS IN THE EAST WIND TONIGHT...BUT AT LEAST A SOLID 15G25KT 
FRI AND LIKELY A BIT STRONGER THAN THAT. WEISHAAR
&&

.MARINE...BORDERLINE ADVISORY SITUATION WITH REGARD TO WIND AND 
SEAS. MAINTAINED THE SMALL CRAFT FOR WIND IN THE NORTH WATERS 
STARTING AT 03Z...AND 12Z OVER THE SOUTH WATERS. HOWEVER...DECIDED 
TO INCLUDED BOTH SOUTHERN ZONES IN THE ADVISORY DUE TO POTENTAL 
GUSTS TO 25 KT NEAR COASTAL GAPS. MAY NEED TO BEGIN THE SOUTH ZONE 
ADVISORY A LITTLE EARLIER AS THE NEWPORT JETTY AND FLORENCE HAVE HAD 
GUSTS OF 20 TO 25 KT THIS AFTERNOON. LOW-END SMALL CRAFT FOR WIND 
EXPECTED TO LAST THROUGH AT LEAST 06Z SUN. SEAS JUST UNDER 10 FT 
THIS AFTERNOON. EXTENDED THE SMALL CRAFT ADVISORY THROUGH 06Z SUN. 
THERE WILL LIKELY BE A PERIOD LATE FRI AND FRI EVENING WHEN SEAS 
DROP BELOW 10 FT BUT FOR SIMPLICITY SAKE DID NOT WANT TO MAKE TWO 
SEPARATE HAZARDS. THE LEADING EDGE OF ANOTHER SWELL TRAIN ARRIVES 
LATE FRI NIGHT AND SAT...PEAKING AROUND 16 FT SAT NIGHT AND SUN.  
WEISHAAR
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...AIR STAGNATION ADVISORY UNTIL 6 PM PST SATURDAY FOR CENTRAL 
     AND SOUTH WILLAMETTE VALLEY.

WA...AIR STAGNATION ADVISORY UNTIL 6 PM PST SATURDAY FOR NORTH 
     CLARK COUNTY AND I5 CORRIDOR IN COWLITZ COUNTY.

PZ...SMALL CRAFT ADVISORY FOR WIND 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 WIND LATE TONIGHT THROUGH SATURDAY
     EVENING FOR COASTAL WATERS FROM CASCADE HEAD TO FLORENCE. 

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS THROUGH SATURDAY
     AFTERNOON CAPE SHOALWATER TO FLORENCE. 

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR THROUGH
     FRIDAY AFTERNOON.

&&

$$

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.