Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 250409
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
908 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. THE UPPER RIDGE WILL AMPLIFY
OVER THE PACIFIC NORTHWEST SATURDAY AND SUNDAY FOR MORE SUNSHINE AND
SIGNIFICANTLY WARMING TEMPERATURES. THE RIDGE WILL REMAIN INLAND OVER
THE NORTHWEST U.S. THROUGH THE MIDDLE OF NEXT WEEK WITH SOUTHWEST
FLOW ALOFT AND HIGH 500 MB HEIGHTS. MARINE CLOUDS CAN BE EXPECTED
NEAR THE COAST...AND ISOLATED THUNDERSTORMS BRUSHING THE OREGON
CASCADE CREST AT TIMES.
&&

.UPDATE...MADE ONLY MINOR CHANGES TO TONIGHT`S SKY COVER WITH THE
EVENING UPDATE. OTHERWISE FORECAST IS ON TRACK WITH A WEAK UPPER
DISTURBANCE CLIPPING SW WASHINGTON FRIDAY MORNING BEFORE AN UPPER
RIDGE BUILDS AND LIFTS THIS DISTURBANCE NORTHWARD FRIDAY AFTERNOON.
GENERAL DRYING AND WARMING THIS WEEKEND INTO NEXT WEEK.

PREVIOUS SHORT TERM DISCUSSION FOLLOWS...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...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS....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...WEAK ONSHORE FLOW WILL LIKELY LEAD TO PREDOMINANTLY
VFR CONDITIONS AT ALL TAF SITES THROUGH 06Z SATURDAY. THE MAIN
EXCEPTION TO THIS WILL BE AT KAST WHERE MVFR CONDITIONS WILL
LIKELY DOMINATE FROM 09Z TO 18Z FRIDAY. THERE IS ALSO A DECENT
CHANCE LOW IFR CONDITIONS WILL DEVELOP AROUND KONP FOR A COUPLE
HOURS NEAR 12Z FRIDAY. CONFIDENCE IS RELATIVELY LOW THAT MVFR
CONDITIONS APPROACHING KAST WILL MAKE THEIR WAY UP THE COLUMBIA
RIVER TO KPDX AND KTTD BY DAYBREAK.

KPDX AND APPROACHES...EXPECT MAINLY VFR CONDITIONS THROUGH 06Z
SATURDAY UNDER WEAK ONSHORE FLOW. CONFIDENCE IS LOW TO MEDIUM MVFR
CONDITIONS WILL DEVELOP BETWEEN 12Z AND 16Z FRIDAY SO PUT A TEMPO
IN THE TAF TO COVER THIS IDEA FOR NOW. /NEUMAN

&&

.MARINE...HIGH PRESSURE BUILDING OVER THE NORTHEAST PACIFIC AND
THERMAL LOW PRESSURE OVER NORTHERN CALIFORNIA WILL STRENGTHEN OVER
THE COMING DAYS. THIS WILL LEAD TO A TYPICAL SUMMERTIME PATTERN OF
GUSTY NORTHERLY WINDS AND POTENTIALLY STEEP SEAS...ESPECIALLY
SOUTH OF NEWPORT. THERE IS A CHANCE WIND GUSTS OF 25 KT WILL
DEVELOP LATE FRIDAY AFTERNOON AND EVENING...BUT SUSPECT THIS MODEL
WINDS ARE SLIGHTLY OVERDONE...BUT PERHAPS A SMALL CRAFT WILL BE
NECESSARY FOR THE CENTRAL OREGON INNER WATERS. BETTER CHANCES FOR
SMALL CRAFT ADVISORIES WILL ARRIVE LATER IN THE WEEKEND INTO NEXT
WEEK...EVEN FOR THE NORTHERN WATERS. /NEUMAN


&&

.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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