Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 192136 CCA
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
230 PM PDT FRI SEP 19 2014

.SYNOPSIS...HIGH PRESSURE IS NOW BUILDING INTO THE REGION BRINGING
MORE SETTLED WEATHER ACROSS THE AREA. ONE EXCEPTION IS ACROSS SW
WASHINGTON AND THE EXTREME NW OREGON COAST WHERE A FEW LIGHT SHOWERS
MAY OCCUR AS A DYING FRONT MOVES INTO WASHINGTON LATE THIS AFTERNOON.
THEN EXPECT A DRY AND WARM WEEKEND AS OFFSHORE FLOW STRENGTHENS.
COOLER AND WET UNSETTLED WEATHER REMAINS ON TAP FOR NEXT WEEK.

&&

.SHORT TERM...TONIGHT THROUGH MONDAY...A WEAK FRONT CAN BE SEEN IN
VISIBLE SATELLITE IMAGERY DRAPED ALONG THE SW WASHINGTON AND FAR NW
OREGON COAST/COAST RANGE EARLY THIS AFTERNOON. SURFACE OBSERVATIONS
ARE NOW SHOWING A LOW OVERCAST CLOUD DECK AT ASTORIA...WITH A TRACE
TO 0.01 INCHES OF PRECIP BEING REPORTED FURTHER NORTH ALONG THE
WASHINGTON COASTLINE. THE FRONT WILL LINGER ALONG THE COAST AND COAST
RANGE THROUGH LATE THIS AFTERNOON BEFORE DISSIPATING BY THIS EVENING.
THIS MORNINGS CLOUDS DISSIPATED QUICKLY TODAY...AND THE AMPLE
SUNSHINE WILL ALLOW AFTERNOON HIGH TEMPERATURES TO BE A FEW DEGREES
WARMER THAN NORMAL. WILL LIKELY SEE INLAND HIGHS TOP OUT NEAR 80
DEGREES TODAY...WARMER IN THE SOUTH WILLAMETTE VALLEY.

UPPER LEVEL HIGH PRESSURE WILL CONTINUE TO BUILD ACROSS THE PACIFIC
NORTHWEST TONIGHT THROUGH THE WEEKEND. A THERMAL TROUGH IS ALREADY
DEVELOPING ALONG THE SOUTH OREGON COAST THIS AFTERNOON...WITH SURFACE
OBSERVATIONS SHOWING INCREASING NORTHERLY WINDS. AS THE THERMAL
TROUGH TRAVELS NORTH ALONG THE COAST TONIGHT...EXPECT OFFSHORE FLOW
TO DEVELOP. THIS MEANS WIDESPREAD WARMER TEMPERATURES ARE EXPECTED
FOR THE WEEKEND AND ESPECIALLY FOR SATURDAY...FOR ONE LAST SUMMERTIME
HURRAH. EXPECT THE WARMEST TEMPERATURES ALONG THE COAST AND PERHAPS
THE SOUTHERN WILLAMETTE VALLEY ON SATURDAY. EUGENE WILL STAND ONE
MORE CHANCE TO ADD TO THEIR RECORD 35 DAYS OF 90F OR HIGHER IN 2014
ON SATURDAY.

EAST WINDS SATURDAY AND MUCH LOWER RELATIVE HUMIDITIES FOR MUCH OF
THE WEEKEND SHOULD ONCE AGAIN PRODUCE CONDITIONS MORE FAVORABLE FOR
WILDFIRE GROWTH...BUT NOT LIKELY EXPLOSIVE GROWTH.  AS A RESULT...AT
LEAST MODEST AMOUNTS OF SMOKE SHOULD SPREAD BACK INTO THE WILLAMETTE
VALLEY FROM THE 36 PIT AND DECEPTION COMPLEX FIRES. MODEL SOUNDINGS
INDICATE A TEMPERATURE INVERSION DEVELOPING AROUND 850-900 MB THIS
WEEKEND RESULTING IN RELATIVELY WARMER OVERNIGHT TEMPERATURES IN THE
CASCADES AND PARTS OF THE COAST RANGE. THE TEMPERATURE INVERSION
SHOULD BREAK IN THE AFTERNOONS TO ALLOW THE AIR MASS TO MIX.

AS THERMAL LOW PRESSURE SHIFTS NORTHWARD TO OFF WASHINGTON LATE
SATURDAY INTO SUNDAY...COOLER MARINE AIR SHOULD SPREAD INTO COASTAL
LOCATIONS AND PERHAPS THE SOUTHERN WILLAMETTE VALLEY SUNDAY...THEN
ACROSS REST OF REGION SUNDAY EVENING. THE THREAT FOR PATCHY FOG/LOW
STRATUS OVER THE SOUTH WILLAMETTE VALLEY ON SUNDAY WILL KEEP HIGHS IN
THE LOWER 80S...WHILE THE REST OF THE VALLEY SEES HIGHS IN THE MID TO
UPPER 80S.  AN APPROACHING LEVEL TROUGH WILL BREAK DOWN THE UPPER
RIDGE THROUGH MONDAY. ONSHORE FLOW INCREASES AS A WEAK FRONTAL BAND
CLIPS THE FORECAST AREA AGAIN. WILL LIKELY SEE A STRONGER MARINE PUSH
INTO THE COASTAL GAPS AND ALONG THE COLUMBIA RIVER SUNDAY
NIGHT/MONDAY MORNING. /27

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...MONDAY NIGHT
THROUGH FRIDAY...AN APPROACHING UPPER LEVEL TROUGH WILL BRING A COOL
AND CLOUDY START TO THE FIRST OFFICIAL WEEK OF FALL. AFTER A COOL
TRANSITION DAY TUESDAY...MODELS SHOW THE NEXT STRONG UPPER LEVEL LOW
BRINGING A WIDESPREAD RAIN EVENT TO THE REGION STARTING LATE TUESDAY
NIGHT AND WEDNESDAY. A COUPLE OF WET DISTURBANCES WILL WRAP AROUND
THE MAIN UPPER LOW IN THE GULF OF ALASKA THROUGH LATE
THURSDAY...BEFORE THE MAIN TROUGH AXIS BEGINS TO SHIFT INLAND BY NEXT
FRIDAY. TEMPERATURES IN THE EXTENDED WILL GENERALLY TREND TOWARDS
SEASONAL NORMALS.

&&

.AVIATION...VFR CONDITIONS TO CONTINUE OVER INLAND PARTS OF NW
OREGON THROUGH 18Z SAT. ALONG THE COAST VFR CONDITIONS THIS
EVENING...BUT AREAS OF IFR CONDITIONS WITH LOW CLOUDS AND FOG LIKELY
TO DEVELOP BETWEEN 08Z AND 12Z TONIGHT...AND LINGER THROUGH 16Z SAT
BEFORE GOING BACK TO VFR CONDITIONS WITH OFFSHORE FLOW.

KPDX AND APPROACHES...VFR CONDITIONS WILL CONTINUE THROUGH 18Z SAT.

&&

.MARINE...LIGHT WINDS FRI AFTERNOON EXPECTED TO TURN TO THE NORTH
AND INCREASE OVERNIGHT. A TROUGH OF LOW PRES DEVELOPING N UP THE
COAST TONIGHT AND SAT WILL LIKELY BRING SMALL CRAFT WINDS TO THE
CENTRAL OREGON COASTAL WATERS OVERNIGHT AND CONTINUE IN SAT MORNING.
FURTHER N WIND GUSTS ARE LIKELY TO PEAK SAT BETWEEN 20 AND 25 KT.
SAT NIGHT A WEAK LOW PRES CENTER WILL MOVE UP OFFSHORE...TURNING
WINDS TO THE S. GUSTS LIKELY TO APPROACH 20 KT SUN.

A WESTERLY SWELL ARRIVING TONIGHT EXPECTED TO INCREASE SEAS TO 8 TO
9 FT SAT...THEN SLOWLY SUBSIDE OVER THE NEXT FEW DAYS.

A MORE ACTIVE PATTERN WILL ARRIVE MID WEEK WITH SMALL CRAFT OR
HIGHER WINDS AND SEAS BUILDING TO OVER 10 FT.
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 11 AM PDT SATURDAY FOR
     COASTAL WATERS FROM CASCADE HEAD OR TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH BAR IN EFFECT FROM NOON TO 4 PM
     PDT SATURDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

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 AS THE FORECAST AREA.


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