FXUS66 KPQR 080331
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
900 PM PDT TUE OCT 07 2008

.SYNOPSIS...SHOWERS WILL CONTINUE TO DECREASE THIS EVENING...ALLOWING
MOST AREAS TO BECOME PARTLY CLOUDY OVERNIGHT. THIS WILL CREATE A GOOD
SETUP FOR AREAS OF FOG TO FORM ALONG THE COAST AND IN THE INTERIOR
VALLEYS...SO EXPECT A FOGGY/CLOUDY START TO WEDNESDAY. WEDNESDAY WILL
BE A DRY DAY...BUT ANOTHER COOL SYSTEM WILL DIG SOUTH OUT OF THE GULF
OF ALASKA AND BRING RAIN TO THE FORECAST AREA BY THURSDAY MORNING.
THIS SYSTEM WILL ALSO BE QUITE COOL ALOFT...AND WILL DROP SNOW LEVELS
BELOW PASS LEVELS FOR THE FIRST TIME THIS SEASON. AN UPPER LEVEL
RIDGE WILL MOVE IN THIS WEEKEND AND EARLY NEXT WEEK FOR DRY AND
WARMER WEATHER AGAIN.
&&

.SHORT TERM...RADAR IMAGERY SHOWS A FEW SHOWERS STILL LINGERING ALONG
THE NORTH COAST AND IN THE SOUTH WASHINGTON CASCADES THIS EVENING.
GIVEN THE PRESENCE OF A 130 KT JET OVERHEAD SHOWER CHANCES SHOULD
CONTINUE IN THESE LOCATIONS OVERNIGHT. SATELLITE IMAGERY SHOWS VERY
LITTLE IN THE WAY OF CLOUD COVER FURTHER OFFSHORE WITH BROKEN
CEILINGS NEAR THE CASCADES. CLOUDS WILL LIKELY BUILD WESTWARD OFF THE
CASCADES LATER TONIGHT. HOWEVER...THE COAST AND VALLEY AREAS INLAND
SHOULD REMAIN RELATIVELY CLOUD FREE THROUGH THE FIRST HALF OF THE
NIGHT AND THIS MAY LEAD TO FOG FORMATION. THE LOCAL ADAPTATION OF THE
UPS FOG FORECASTING TECHNIQUE SECONDS THE NOTION OF FOG TONIGHT. THUS
WILL GO FOR SOME PATCHY FOG ALONG THE COAST TONIGHT...WITH AREAS OF
FOG AND LOW STRATUS INLAND.

THE NEXT SYSTEM DIGS SOUTH OUT OF THE GULF OF ALASKA WEDNESDAY NIGHT
AND THURSDAY. FRONTAL PRECIP APPEARS TO MAKE IT TO THE COAST EARLY
THURSDAY MORNING...THEN SWEEP THROUGH THE AREA BY THURSDAY AFTERNOON
AND EVENING. THIS WILL BE FOLLOWED BY MORE SHOWERS. SNOW LEVELS THEN
DROP WELL BELOW THE CASCADE PASSES BY THURSDAY NIGHT...POSSIBLY AS
LOW AS 2500 FEET IN THE SOUTH WASHINGTON CASCADES. THIS WILL BE THE
LOWEST OF THE FALL SEASON THUS FAR. PRECIPITATION AMOUNTS LOOK A BIT
WEAK FOR A SNOW ADVISORY BUT MIGHT GET CLOSE AT HIGHER ELEVATIONS.
WINDS WILL BE A BIT BREEZY FROM THE NORTHWEST THURSDAY ESPECIALLY AT
THE COAST AND OVER THE MOUNTAINS. MODELS KEEP PRECIP IN THE FORECAST
FOR THE CENTRAL OREGON CASCADES AND THE CASCADES OF LANE COUNTY
THROUGH FRIDAY MORNING...SO KEPT IN SOME SLIGHT CHANCE POPS FOR THOSE
AREAS THROUGH EARLY FRIDAY MORNING.

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
MODELS CUTOFF AN UPPER LOW OVER THE GREAT BASIN ON SATURDAY...FORCING
A STRONG AND SHARP UPPER LEVEL RIDGE TO DEVELOP OVER THE NORTHEAST
PACIFIC AND INTO BRITISH COLUMBIA. THIS WOULD PROVE TO BE NICE FALL
WEATHER FOR THE FORECAST AREA OVER THE WEEKEND. MODELS THEN KICK THE
CLOSED LOW OFF TO THE EAST AND ALLOW PACIFIC SYSTEM TO SWING THROUGH
BY MONDAY AFTERNOON. MODELS ALL AGREE ON THIS GENERAL SOLUTION FOR
NOW...SO FORECAST REFLECTS THIS CONFIDENCE.   DALTON
&&

.AVIATION...MOST SHOWERS HAVE DIED THIS EVENING WITH MOST OF THE
CONVECTIVE CLOUDS NOW LIMITED TO THE MOUNTAINS AS ONSHORE FLOW
CONTINUES. LOW LEVELS ARE STILL RELATIVELY MOIST AND WITH THE
ATMOSPHERE DECOUPLING AS HIGH PRESSURE MOVES IN...EXPECT SOME LOW
CLOUDS AND/OR FOG TO DEVELOP FOR IFR TO MVFR CONDITIONS LATE
TONIGHT AND WED MORNING ESP IN THE VALLEY. BELIEVE LOW CLOUDS ARE
MOST LIKELY TO FORM BANKED UP AGAINST THE CASCADES...WHILE BEST
CHANCES FOR FOG SHOULD BE OVER THE WEST SIDE OF THE VALLEY.

.KPDX AND APPROACHES...MOSTLY CLEAR SKIES EXPECTED TO CONTINUE
THROUGH THE LATE EVENING. EXPECT EVENTUALLY TO DEVELOP SOME LOW
CLOUDS OR FOG LATE TONIGHT FOR MVFR OR IFR CONDITIONS FROM LATE
TONIGHT THROUGH WED MORNING.
&&

.MARINE...WINDS TO CONTINUE TO DIE DOWN OVERNIGHT AS HIGH PRESSURE
MOVES ACROSS. NEXT BEST CHANCE TO PUSH WINDS INTO SMALL CRAFT RANGE
NOT UNTIL THU. W SWELL STILL IN LOW TEENS AT INNER BUOYS...BUT OUTER
BUOYS SUCH AS 089 AND 005 SUPPORT MODEL TRENDS OF LOWERING SWELL
BELOW 10 FT BY MORNING.
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR/WA...SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR
          THROUGH WED MORNING.
        SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS CAPE SHOALWATER
          TO FLORENCE THROUGH WED MORNING.
&&

$$

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.