Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 242150
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
249 PM PDT THU JUL 24 2014

.SYNOPSIS...THE UPPER LEVEL LOW THAT BROUGHT ABUNDANT RAIN TO
SOUTHWEST WASHINGTON AND NORTHWEST OREGON THE PAST TWO DAYS HAS MOVED
WELL EAST OF THE AREA THIS AFTERNOON WITH CONTINUED ONSHORE FLOW BUT
DECREASING SHOWERS. A WEAK UPPER RIDGE WILL BEGIN MOVING INTO THE
AREA THROUGH TONIGHT AND FRIDAY IN ITS WAKE...WITH MORE AFTERNOON
SUNSHINE AND GRADUAL WARMING ON FRIDAY. THE UPPER RIDGE WILL AMPLIFY
OVER THE PACIFIC NORTHWEST SATURDAY AND SUNDAY FOR MORE SUNSHINE AND
SIGNIFICANTLY WARMING TEMPERATURES...AND WITH LESS LOW CLOUDS. AN
UPPER LEVEL RIDGE WILL REMAIN INLAND OVER THE NORTHWEST U.S. THROUGH
THE MIDDLE OF NEXT WEEK WITH SOUTHWEST FLOW ALOFT BUT HIGH 500 MB
HEIGHTS...FOR SOME MARINE INFLUENCE MAINLY NEAR THE COAST...AND A FEW
THUNDERSTORMS POSSIBLY BRUSHING THE OREGON CASCADE CREST AT
TIMES...AND CONTINUED WARM WEATHER INLAND.
&&

.SHORT TERM...THE LOW THAT HAD PLAGUED SOUTHWEST WASHINGTON AND
NORTHWEST OREGON THE PAST TWO DAYS WITH COPIOUS RAINFALL HAS MOVED
EAST OF THE CASCADES IN WASHINGTON THIS AFTERNOON. SIGNIFICANT
ONSHORE FLOW CONTINUES IN ITS WAKE IN THE LIGHT WESTERLY FLOW ALOFT.
THERE ARE A FEW SHOWERS REMAINING MAINLY TILLAMOOK TO VANCOUVER
NORTHWARD...BUT THESE SHOULD DECREASE EARLY THIS EVENING. THERE ARE A
LOT OF CLOUDS OVER SOUTHWEST WASHINGTON AND NORTHWEST OREGON THIS
AFTERNOON...AND PLENTY UPSTREAM OVER THE NORTHEAST PACIFIC THAT WILL
ADVECT IN OVERNIGHT TONIGHT. I THINK THE BEST CHANCE FOR MUCH
CLEARING THIS EVENING WILL BE SOUTH LANE COUNTY...BUT SOME CLOUDS MAY
FILTER IN OVERNIGHT DOWN THERE AS WELL.

THE MODELS REALLY DO NOT SHOW MUCH IF ANY UPPER RIDGING TONIGHT...
WITH THE UPPER FLOW EVEN SLIGHTLY CYCLONIC AT 12Z FRIDAY. THUS EXPECT
FAIRLY DECENT LOW CLOUD COVERAGE THROUGH TONIGHT AND INTO FRIDAY
MORNING ACROSS OUR FORECAST AREA. THERE IS A WEAK DISTURBANCE AROUND
50N/130W THIS AFTERNOON THAT MAY BE THE FEATURE DEVELOPING SOME
PATCHY QPF ALONG THE NORTH COAST FORECAST ZONES EARLY FRIDAY...AND IS
ALSO PROBABLY PART OF WHY THE LOW CLOUDS WILL BE RATHER SOLID TONIGHT
INTO FRIDAY. SO WILL LEAVE THE CHANCE OF SPRINKLES AND DRIZZLE IN FOR
LATER TONIGHT AND FRIDAY MORNING NEAR THE NORTH COAST AND COASTAL
MOUNTAINS.

500 MB HEIGHTS DO BEGIN TO BUILD A BIT FRIDAY SO WE SHOULD SEE MORE
SUNSHINE DEVELOP FRIDAY AFTERNOON THAN WE HAVE SEEN IN SEVERAL DAYS.
TEMPS INLAND SHOULD PUSH INTO THE UPPER 70S TO NEAR 80. CLOUDS ON THE
NORTH COAST MAY AGAIN TEND TO HANG ON FOR A WHILE IN THE AFTERNOON
DUE TO THE WEAK DISTURBANCE THAT CAUSES THE PATCHY LIGHT MORNING
PRECIPITATION.

THE UPPER RIDGE AMPLIFIES IN EARNEST FRIDAY NIGHT AND ESPECIALLY
SATURDAY...WITH 500 MB HEIGHTS INTO THE LOWER TO MID 580S BY SATURDAY
AFTERNOON. AFTER SOME BRIEF MORNING LOW CLOUDS INLAND ALONG THE
COLUMBIA RIVER...LOOK FOR PLENTY OF SUNSHINE AND INLAND TEMPS INTO
THE MID 80S ON SATURDAY. THERE IS NOT MUCH CHANGE ON SUNDAY... EXCEPT
TEMPS INLAND MAY GET CLOSER TO 90. THE MODELS SHOW A WEAK DISTURBANCE
LIFTING UP INTO CENTRAL OREGON FROM THE SOUTHWEST ON SUNDAY THAT
MIGHT BRUSH OUR OREGON CASCADE CREST AREA WITH AN ISOLATED
THUNDERSTORM OR TWO SUNDAY AFTERNOON AND EVENING. TOLLESON

.LONG TERM....A LARGE UPPER-LEVEL RIDGE IS FORECAST TO BE POSITIONED
OVER THE ROCKY MOUNTAINS...PUTTING OUR REGION UNDER SOUTHWESTERLY
FLOW ALOFT NEXT WEEK. SEVERAL WEAK SHORTWAVES ARE FORECAST UP THE
RIDGE NEAR OUR REGION.MOST OF THESE LOOK LIKE THEY WILL MISS OUR
AREA...BUT A CHANCE FOR SOME SCATTERED THUNDERSTORMS ARE POSSIBLE
ALONG THE CASCADE CREST WEDNESDAY AND THURSDAY. THE SOUTHWESTERLY
FLOW AND SUNNY AFTERNOONS WILL KEEP OUR TEMPERATURES ABOVE NORMAL.
-MCCOY
&&

.AVIATION...MOSTLY VFR CONDITIONS NOW IN CONTROL THIS AFTERNOON...
EXCEPT FOR SOME MVFR CIGS ALONG THE S WA AND N OR COAST WHICH SHOULD
LIFT OVER THE NEXT COUPLE OF HRS. MID LEVEL CLOUDS OVER THE REGION ON
THE LATEST SAT IMAGERY SHOULD SCATTER SOMEWHAT THIS AFTERNOON AND
THIS EVENING. BUT WITH NW ONSHORE FLOW NOW IN PLACE ACROSS THE
REGION...EXPECT CIGS TO LOWER BACK DOWN TO MVFR OVER THE N COAST
OVERNIGHT...AND TRY TO PUSH UP THE LOWER COLUMBIA INTO THE N VALLEY.
A HIGH MVFR DECK MAY ALSO TRY TO FORM ALONG THE CASCADE FOOTHILLS AND
BACK BUILD INTO KTTD AND KPDX AFTER 12Z FRI. SOME LOW STRATUS OR
PATCHY FOG IS A POSSIBILITY ALONG THE CENTRAL OR COAST
OVERNIGHT...WHERE LIGHT OFFSHORE DRIFT MAY DEVELOP. CONDITIONS SHOULD
RETURN TO WIDESPREAD VFR BY 17Z TO 19Z FRI.

KPDX AND APPROACHES...MOSTLY VFR CONDITIONS TODAY. THE ONLY EXCEPTION
MAY BE A BRIEF PERIOD OF MVFR CIGS THROUGH 18Z IN A PASSING SHOWER.
CLOUDS BREAKING UP SIGNIFICANTLY LATE THIS AFTERNOON AND THIS
EVENING. PYLE
&&

.MARINE...LOW PRES HAS MOVED INLAND AND NW FLOW LESS THAN 15 KT IS
NOW IN CONTROL OVER THE COASTAL WATERS. SEAS REMAIN A BIT ON THE
CHOPPY SIDE WITH PERIODS OF 8 TO 9 SEC...BUT WAVE HEIGHTS HAVE
SUBSIDED A LITTLE TODAY AND CURRENTLY SIT IN THE 6 TO 8 FT RANGE.
EXPECT SEAS TO CONTINUE GRADUALLY DIMINISHING...REACHING 4 TO 5 FT BY
LATE EVENING.

HIGH PRES WILL BEGIN TO BUILD OVER NE PAC TONIGHT AND FRI...WITH
THERMAL LOW PRES BUILDING OVER NW CALIF. THIS WILL BRING A MORE
TYPICAL SUMMERTIME PATTERN OF GUSTY NORTHERLY WINDS...AND POTENTIALLY
STEEP SEAS...ESPECIALLY S OF NEWPORT. WINDS WILL START TO INCREASE
FRI AFTERNOON AND EVENING...POSSIBLY REACHING LOW END SMALL CRAFT
ADVISORY SPEEDS OVER THE CENTRAL OR WATERS. THE SURFACE PRES GRADIENT
WILL THEN STRENGTHEN OVER THE WEEKEND INTO EARLY NEXT WEEK...WITH
SOLID SMALL CRAFT ADVISORY WINDS EXPECTED BY SUN AND CONTINUING
THROUGH MUCH OF NEXT WEEK.

A STRONG EBB WILL BRING CHOPPY CONDITIONS ON THE COLUMBIA RIVER BAR
DURING THE EBB AROUND 430 AM FRI MORNING. PYLE
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM
     3 AM TO 6 AM PDT FRIDAY.

&&

$$

MORE WEATHER INFORMATION ONLINE AT...HTTP://WEATHER.GOV/PORTLAND

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
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.



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