Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 201015
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
315 AM PDT SAT SEP 20 2014

.SYNOPSIS...THERMAL LOW PRESSURE OVER SW OREGON COAST WILL BUILD
NORTH ALONG THE PAC NW COAST TODAY...AS HIGH PRESSURE REMAINS INLAND.
EASTERLY WINDS WILL KEEP SKIES SUNNY AND SUPPORT TEMPERATURES IN THE
80S FOR THE COAST AND POSSIBLY LOW 90S FOR INLAND AREAS TODAY. COOLER
ONSHORE FLOW WILL RETURN SUNDAY.MONDAY WILL BE MOSTLY CLOUDY AS A
WEAK FRONT BRUSHES BY. A STRONGER FRONT WILL LIKELY BRING WIDESPREAD
RAIN WEDNESDAY.

&&

.SHORT TERM...TODAY THROUGH MONDAY NIGHT...SATELLITE IMAGERY SHOWS A
SLIVER OF LOW MARINE CLOUDS ALONG THE IMMEDIATE COAST EARLY THIS
MORNING. THE SKIES ARE OTHERWISE CLEAR...EXCEPT MARINE STRATUS IS
STARTING TO PUSH UP THE LOWER COLUMBIA RIVER. LIGHT NORTHERLY WINDS
THIS MORNING WILL BE REPLACED BY EASTERLY WINDS LATE THIS MORNING AS
A THERMAL TROUGH PUSHES OFF THE COAST. THE EASTERLY WINDS WILL BE
GUSTY THROUGH THE COLUMBIA RIVER GORGE AND CASCADE GAPS...AND WILL
SUPPORT A SUNNY AND WARM DAY. TEMPERATURES WILL LIKELY PEAK IN THE
LOW 90S FOR THE INTERIOR VALLEY AND MID TO UPPER 80S FOR THE COAST.

EAST WINDS AND LOW RELATIVE HUMIDITIES WILL PRODUCE CONDITIONS
FAVORABLE FOR WILDFIRE GROWTH...AND SMOKE FROM THE 36-PIT AND
DECEPTION FIRES SHOULD SPREAD BACK INTO THE WILLAMETTE
VALLEY TODAY.

THE THERMAL TROUGH WILL WEAKEN THIS EVENING AND SOUTHERLY WINDS WILL
DEVELOP ALONG THE COAST. LOW MARINE CLOUDS CURRENTLY OVER NORTHERN
CALIFORNIA WILL SURGE NORTHWARD AND REACH NEWPORT TONIGHT. THE LOW
CLOUDS WILL CONTINUE TO SLIDE NORTHWARD ALONG THE COAST AND REACH
ASTORIA SHORTLY AFTER SUNRISE SUNDAY MORNING. THIS WILL RESULT IN
DRASTIC COOLING FOR THE OREGON COAST. ONSHORE WINDS SUNDAY AFTERNOON
WILL BRING THE COOLER MARINE AIR INLAND AND TEMPERATURES SHOULD PEAK
IN THE MID 80S FOR THE INTERIOR VALLEYS AND THE 60S FOR THE COAST

AN UPPER LEVEL TROUGH WILL APPROACH SUNDAY NIGHT AND THE MARINE
STRATUS WILL PUSH FURTHER INLAND MONDAY MORNING. A WEAK SURFACE FRONT
WILL MAINTAIN CLOUDY SKIES...AT LEAST TO NORTHERN AREAS...THROUGH
MONDAY AFTERNOON. DO NOT EXPECT MUCH IF ANY RAIN FROM THIS
FRONT...JUST A FEW SPRINKLES HERE AND THERE MONDAY NIGHT. TJ

.LONG TERM...A STRONGER COLD FRONT WILL APPROACH TUESDAY AND BRING
WIDESPREAD RAIN TO THE REGION WEDNESDAY. MODELS SHOW PRECIPITABLE
WATER APPROACHING 1.5 INCHES WITH THIS FRONT...AND A 120KT 500MB JET
TO PROVIDE LIFT. THIS MAY RESULT IN SOME AREAS MEASURING AN INCH OR
MORE OF RAIN. A COUPLE OF WET DISTURBANCES WRAPPING AROUND THE MAIN
UPPER LOW IN THE GULF OF ALASKA WILL MAINTAIN COOL AND SHOWERY
WEATHER THROUGH THE END OF THE WEEK...AND POSSIBLY INTO THE WEEKEND.
TJ

&&

.AVIATION...GENERALLY VFR CONDITIONS WILL CONTINUE OVER NW OREGON
AS OFFSHORE FLOW INCREASES TODAY AND EASES TONIGHT. THERE WILL BE
SOME PATCHY FOG AND LOW CLOUDS ALONG THE COAST THROUGH 16Z.

KPDX AND APPROACHES...VFR CONDITIONS WILL CONTINUE THROUGH 06Z
SUN. EAST WINDS INCREASE IN THE AREA LATER THIS MORNING THROUGH
THE AFTERNOON...THEN EASE TONIGHT. EAST WIND PROBABLY SURFACING AT
KPDX AROUND 18Z AND PEAKING 21Z SAT THRU 00Z SUN.

&&

.MARINE...MARGINAL SMALL CRAFT ADVISORY NORTHERLY WINDS OVER THE
CENTRAL COAST THIS MORNING WITH A LESSER CHANCE TO SEE SMALL CRAFT
WINDS FURTHER N. WINDS SHOULD EASE IN THE AFTERNOON AS THE THERMAL
TROUGH EXPANDS OVER THE WATERS...EASING THE PRESSURE GRADIENTS.
TONIGHT A WEAK LOW PRES CENTER WILL MOVE UP OFFSHORE...TURNING
WINDS TO THE S. GUSTS LIKELY TO APPROACH 20 KT SUN. SHALLOW
STRATUS AND FOG USUALLY COME WITH THE WIND REVERSAL.

A WESTERLY SWELL 8 TO 9 FT ARRIVED IN THE NORTHERN ZONES AND
SHOULD FILL IN THE SOUTHERN ZONES THIS MORNING. SEAS 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 THIS MORNING FOR
     COASTAL WATERS FROM CASCADE HEAD OR TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM NOON
     TODAY TO 4 PM PDT THIS AFTERNOON.

&&

$$

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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