Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 222203
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
303 PM PDT FRI AUG 22 2014

.SYNOPSIS...A LOW EAST OF THE AREA MAY GENERATE SOME SHOWERS OR
THUNDERSTORMS ALONG THE SOUTH WASHINGTON AND NORTHERN OREGON CASCADES
THIS AFTERNOON AND EVENING. NORTHERLY FLOW ALOFT CONTINUES FOR THE
WEEKEND MAINTAINING ONSHORE LOW-LEVEL FLOW AND SEASONAL TEMPERATURES.
AN UPPER LEVEL TROUGH FROM THE NORTH WILL MOVE SOUTHWARD ACROSS
EASTERN WASHINGTON SUNDAY AND POSSIBLY GENERATE SOME AFTERNOON
SHOWERS TO THE NORTHERN CASCADES. HIGH PRESSURE STRENGTHENS MONDAY
BRINGING A WARM UP FOR THE FIRST HALF OF NEXT WEEK.

&&

.SHORT TERM...THIS AFTERNOON THROUGH SUNDAY NIGHT...SKIES HAVE
CLEARED ACROSS THE REGION THIS AFTERNOON WITH LINGERING
STRATO-CUMULUS OVER THE HIGHER TERRAIN AND LINGERING STRATUS ALONG
THE NORTH COAST. SOME SHOWERS ARE SPROUTING UP EAST OF MOUNT
ADAMS...JUST EAST OF THE CASCADE CREST THIS AFTERNOON. THESE SHOWERS
MAY DEVELOP INTO THUNDERSTORMS OVER THE SOUTHWEST WASHINGTON CASCADES
THIS AFTERNOON AND EVENING. NORTHERLY FLOW MAY HELP THESE SHOWERS
DRIFT OVER THE NORTHERN OREGON CASCADES...BUT THEY SHOULD REMAIN
MOSTLY EAST OF THE CASCADE CREST. THESE SHOWERS ARE A DUE TO A LOW
CENTERED OVER THE EASTERN OREGON/WASHINGTON BORDER.

SATELLITE IMAGERY SHOWS MARINE STRATUS ALONG THE WASHINGTON COAST.
NORTHERLY FLOW DUE TO BUILDING HIGH PRESSURE MAY FEED THESE CLOUDS
TOWARDS THE NORTHERN OREGON COAST THIS AFTERNOON AND EVENING...AND
THERE MAY NOT BE MUCH CLEARING ALONG THE COAST NORTH OF TILLAMOOK BAY
TONIGHT. THE MARINE LAYER WILL BE SHALLOWER TONIGHT AND DO NOT EXPECT
STRATUS TO MOVE VERY FAR INLAND SATURDAY MORNING. HOWEVER... WEAK
ONSHORE WINDS WILL PUSH SOME STRATUS THROUGH THE LOWER COLUMBIA
RIVER...POSSIBLY REACHING KELSO AND SCAPOOSE.

NORTH TO NORTHWEST WINDS WILL PERSIST SATURDAY AS HIGH PRESSURE
CONTINUES TO BUILD OVER THE AREA...AND AFTERNOON TEMPERATURES WILL BE
NEAR THEIR SEASONAL NORMALS...WITH LOW TO MID 80S FOR THE INTERIOR
VALLEYS...AND MID TO UPPER 60S ALONG THE COAST. ANOTHER SHALLOW
MARINE LAYER SHOULD LIMIT THE INLAND PENETRATION OF STRATUS EVEN MORE
SATURDAY NIGHT...BUT AN APPROACHING TROUGH FROM THE NORTH MAY
INFLUENCE SOME VISIBILITY-REDUCING FOG ALONG THE IMMEDIATE COAST.

A SURFACE LOW EAST OF THE CASCADES WILL STRENGTHEN ONSHORE WINDS
SUNDAY AS THE UPPER TROUGH FROM THE NORTH CONTINUES TO DIG SOUTHWARD.
MODELS ARE SHOWING SOME SHOWERS WITH THIS LOW BRUSHING BY THE SOUTH
WASHINGTON CASCADES SUNDAY AFTERNOON...AND HAVE ADDED POPS TO THE
FORECAST. NORTHWEST FLOW SHOULD KEEP THE THREAT FOR THUNDERSTORMS
EAST OF THE CASCADES THOUGH. EXPECT A DEEPER MARINE PUSH SUNDAY NIGHT
AS ANOTHER UPPER SHORTWAVE MOVES OVER THE PACIFIC NORTHWEST. TJ

.LONG TERM...THE UPPER LEVEL RIDGE IS STILL FORECASTED TO MOVE
ONSHORE ON TUESDAY ALLOWING OUR TEMPERATURES TO INCREASE SLIGHTLY
ABOVE SEASONAL NORMS FOR THE BEGINNING PART OF NEXT WEEK. AS THIS
RIDGE PROGRESSES EASTWARD WE WILL LIKELY SEE SOME ZONAL UPPER LEVEL
FLOWS DEVELOP OVER THE FORECAST AREA ALLOWING LOW AND MID LEVEL
MOISTURE TO MOVE IN AND PROVIDE FOR AN INCREASE IN CLOUD COVER OVER
MUCH OF THE CWA ON LATE WEDNESDAY. BEYOND WEDNESDAY...BOTH THE GFS
AND ECMWF ARE HINTING AT A SHORTWAVE MOVING THROUGH OUR REGION AS
THE MEAN LONGWAVE TROUGH MOVES DOWN FROM THE GULF OF ALASKA. THIS
COULD BRING A CHANCE OF RAIN SHOWERS TO THE NORTHERN CASCADES FOR
THE LATTER PART OF NEXT WEEK. THE TIMING AND LOCATION ARE STILL
UNCERTAIN AT THIS POINT AND WILL BE NARROWED DOWN WITH FUTURE
UPDATES. /64
&&

.AVIATION...HIGH PRESSURE AND BROAD NORTHERLY FLOW OVER THE REGION
HAS RESULTED IN MAINLY VFR CONDITIONS ACROSS THE FORECAST AREA THIS
AFTERNOON. HOWEVER...STRATUS LINGERING OFFSHORE SHOULD PUSH ONTO
THE COAST THIS EVENING...ESPECIALLY AT KAST. CONFIDENCE IS NOT
QUITE AS HIGH THAT THIS WILL OCCUR AT KONP...BUT SUSPECT PERIODS
OF IFR CONDITIONS WILL ONCE AGAIN DEVELOP OVERNIGHT AND LAST INTO
THE MORNING HOURS. FURTHER INLAND...LOW LEVEL WINDS WILL TURN
INCREASINGLY NORTHEASTERLY OVERNIGHT...WHICH SHOULD PRODUCE VFR
CONDITIONS AT ALL WILLAMETTE VALLEY TAF SITES THROUGH 00Z SUNDAY.

KPDX AND APPROACHES...HIGH PRESSURE AND INCREASING NORTHEASTERLY
FLOW OVERNIGHT SHOULD RESULT IN VFR CONDITIONS THROUGH 00Z
SUNDAY. /NEUMAN

&&

.MARINE...HIGH PRESSURE WILL CONTINUE OVER THE NORTHEAST PACIFIC INTO
THE FORESEEABLE FUTURE. HOWEVER...THERMAL LOW PRESSURE OVER INTERIOR
CALIFORNIA WILL SHIFT MORE SQUARELY OVER THE COAST SATURDAY AND AGAIN
EARLY NEXT WEEK...IN A PATTERN THAT HAS BEEN RELATIVELY RARE THIS
SUMMER. THIS SHOULD PRODUCE WIDESPREAD NORTHERLY WINDS OF 25 TO 30
KT ACROSS THE CENTRAL OREGON WATERS. WITH A WESTERLY SWELL REMAINING
4 FT OR LESS DURING THIS TIME...SEAS MAY ALSO BECOME WIND DOMINATED
AND ESPECIALLY STEEP AND HAZARDOUS. HOWEVER...CONFIDENCE IS NOT
PARTICULARLY HIGH YET SO WILL HOLD OFF ON A SMALL CRAFT ADVISORY
FOR HAZARDOUS SEAS. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 2 PM SATURDAY TO 3 AM PDT
     SUNDAY FOR COASTAL WATERS FROM CASCADE HEAD OR TO FLORENCE OR
    OUT 60 NM.

&&

$$

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.



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