FXUS66 KPQR 221035
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
235 AM PST TUE DEC 22 2009
	
.SYNOPSIS...SHOWERS WILL CONTINUE THROUGH TODAY IN COOL ONSHORE FLOW.
SNOW WILL FALL IN THE COAST RANGE...CASCADES AND FOOTHILLS...AS WELL
AS THE HIGHER HILLS IN THE WILLAMETTE VALLEY. SHOWERS WILL TAPER OFF
BY MIDDAY. DRY WEATHER WILL PREVAIL THROUGH AT LEAST CHRISTMAS AS A
STRONG UPPER LEVEL RIDGE BUILDS ALONG THE COAST. BRISK EAST WINDS
WILL DEVELOP NEAR THE COLUMBIA RIVER GORGE WEDNESDAY NIGHT AND MAY
CONTINUE THROUGH THE WEEKEND AS THE RIDGE CONTINUES TO HOLD.

&&

.SHORT TERM...DOPPLER RADAR CONTINUES TO SHOW SHOWERS MOVING ACROSS
THE FORECAST AREA THIS MORNING IN COOL ONSHORE FLOW. THE SNOW LEVEL
IS AROUND 1500 FEET...AND BRIEFLY DOWN TO AROUND 1000 FEET IN HEAVIER
SHOWERS. THE SNOW LEVEL WILL SETTLE DOWN TO 800 TO 1000 FEET
OVERNIGHT AS 850 MB TEMPS BOTTOM OUT AT AROUND -6 DEGREES TUESDAY
MORNING. THIS MEANS THAT HILLTOPS AT AND ABOVE 1000 FEET COULD SEE A
QUICK SLUSHY INCH OF SNOW OVERNIGHT IF A HEAVIER SHOWER MOVES
OVERHEAD. THE LOW LEVEL FLOW WILL STAY STRONGLY ONSHORE SO NO THREAT
OF SNOW TO THE VALLEY FLOOR. WILL MAINTAIN ALL CURRENT WINTER WEATHER
ADVISORIES FOR SNOW. 

SHOWERS WILL EASE LATER TODAY AND TONIGHT AS AN UPPER LEVEL RIDGE
BUILDS OVERHEAD. THE MODELS ARE NOW IN BETTER AGREEMENT KEEPING US
DRY THROUGH THE SHORT TERM. THE MAIN FORECAST ISSUES IN THE
WEDNESDAY-THURSDAY TIME FRAME WILL BE THE DEVELOPMENT OF GUSTY EAST
WINDS NEAR THE GORGE AND VALLEY FOG AWAY FROM THE GORGE. LIKENS

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...THE UPPER
LEVEL RIDGE TRANSITIONS THROUGH THE FORECAST AREA THROUGH THE END OF
THE WEEK...WITH DRY WEATHER CONTINUING FRIDAY AFTER LATE NIGHT AND
EARLY MORNING VALLEY FOG. MODELS VARY A LOT WITH THE BREAKDOWN OF THE
RIDGE NEXT WEEKEND AND THE ARRIVAL OF ANY SUBSEQUENT SYSTEMS...AS
SHOWN BY INCREASING ENSEMBLE SPREADS. HAVE LOWERED POPS THROUGH THE
EXTENDED TO SLIGHTLY BELOW CLIMATOLOGY GIVEN THE CONTINUED INFLUENCE
OF THE RIDGE. BROWN

&&

.AVIATION...UPPER AND SURFACE TROUGH MOVING INTO WESTERN WASHINGTON 
AND OREGON. AS A RESULT INCREASED SHOWER ACTIVITY INLAND EARLY THIS 
MORNING WITH BRING MORE MVFR CONDITIONS ESPECIALLY NORTH OF KSLE 
THROUGH ABOUT 20Z TODAY.  THE TROUGH WEAKENS AND SHIFTS FURTHER 
INLAND WITH MAINLY VFR CONDITIONS EXPECTED THROUGH THE EVENING. 
HOWEVER STABLE PATTERN OVERNIGHT CONDUCIVE TO SOME IFR FOG FORMATION.

KPDX AND APPROACHES...MOSTLY VFR BUT MVFR EXPECT MORE MVFR...WITH 
CIGS 2500 TO 3000 FT...THROUGH ABOUT 18Z. VFR AFTER THAT. 

&&

.MARINE...SMALL CRAFT ADVISORY FOR WINDS THROUGH THIS MORNING. FEW 
GUSTS INTO THE GALE CATEGORY EARLY THIS MORNING IN THE NORTHERN 
OUTER WATERS BUT TREND IS DOWNWARD.  SMALL CRAFT ADVISORY FOR SEAS 
UNTIL THIS EVENING. NO MAJOR WEATHER EXPECTED FROM WED THROUGH FRI 
AS HIGH PRES OVER PAC NW KEEPS COASTAL WATERS DRY WITH OFFSHORE 
WINDS.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL NOON PST TUESDAY FOR UPPER HOOD 
     RIVER VALLEY-WESTERN COLUMBIA RIVER GORGE.

     WINTER WEATHER ADVISORY UNTIL NOON PST TUESDAY FOR CASCADE 
     FOOTHILLS IN LANE COUNTY-NORTHERN OREGON CASCADE FOOTHILLS.

     WINTER WEATHER ADVISORY UNTIL 10 AM PST TUESDAY FOR CENTRAL 
     COAST RANGE OF WESTERN OREGON-COAST RANGE OF NORTHWEST 
     OREGON.

WA...WINTER WEATHER ADVISORY UNTIL NOON PST TUESDAY FOR WESTERN 
     COLUMBIA RIVER GORGE.

     WINTER WEATHER ADVISORY UNTIL NOON PST TUESDAY FOR SOUTH 
     WASHINGTON CASCADE FOOTHILLS.

     WINTER WEATHER ADVISORY UNTIL 10 AM PST TUESDAY FOR WILLAPA 
     HILLS.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL NOON FOR 
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR 
     FROM 10 TO 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 PM PST TUESDAY 
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR FROM
     10 TO 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 5 PM 
     PST TUESDAY.

&&

$$

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.