Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 281623
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
922 AM PDT FRI AUG 28 2015

.SYNOPSIS...THE FORECAST STILL SEEMS ON TRACK AS A VERY SIGNIFICANT
PATTERN CHANGE IS ALREADY UNDERWAY FOR THE NEXT WEEK OR SO. A LOW
PRESSURE SYSTEM OFF THE COAST IS GAINING STRENGTH. THE FIRST WAVE OF
MOISTURE RIDING ALONG A FRONTAL BOUNDARY LOCATED ALONG THE PACIFIC
NORTHWEST COAST HAS MOVED ONSHORE THIS MORNING AND WILL TEND TO LIFT
NORTH OF OUR FORECAST AREA THROUGH THE REMAINDER OF TODAY AND THIS
EVENING. THE MOST SIGNIFICANT SYSTEM OF THE BUNCH IS A LOW THAT IS
DEVELOPING AND GAINING STRENGTH BETWEEN 130W AND 140W NEAR 40N THAT
WILL LIFT NORTH LATE TONIGHT AND SATURDAY MORNING. THIS SYSTEM WILL
HAVE A UNSEASONABLY STRONG SURFACE LOW MOVE NORTHWARD JUST OFF THE
COAST AND WILL LIKELY PRODUCE HIGH WIND ALONG THE COASTAL STRIP AND
POSSIBLY OVER THE HIGHER ELEVATIONS AND EXPOSED AREAS OF THE COAST
RANGE. A FEW THUNDERSTORMS ARE ALSO POSSIBLY NEAR THE COAST. THIS LOW
MOVES NORTH SATURDAY AFTERNOON BUT ANOTHER FRONT WILL APPROACH THE
COAST WITH ANOTHER GOOD SHOT OF RAIN AND BREEZY CONDITIONS LATE
SATURDAY AND MOVE THROUGH SOUTHWEST WASHINGTON AND NORTHWEST OREGON
SATURDAY NIGHT. THE PATTERN WILL REMAIN COOLER AND UNSETTLED THROUGH
MUCH OF THE COMING WEEK...WITH ANOTHER DECENT SHOT OF RAIN LATER
TUESDAY INTO WEDNESDAY.
&&

.SHORT TERM...AS EXPECTED...THE FORECAST STILL SEEMS WELL ON TRACK
WITH OUR VERY SIGNIFICANT CHANGE IN THE WEATHER. AN INITIAL WAVE
ALONG A FRONTAL BOUNDARY HAS BROUGHT SOME LIGHT RAIN TO PARTS OF
SOUTHWEST WASHINGTON AND NORTHWEST OREGON...WITH THE BEST AMOUNTS...
TWO TO THREE TENTHS OF AN INCH...ALONG THE COAST THIS MORNING. THIS
WAVE WILL LIFT NORTH THROUGH THE DAY...WITH PRECIPITATION TAPERING
OFF THE REMAINDER OF THE AFTERNOON AND EVENING.

THE STRONGEST SYSTEM OF THE EXPECTED SERIES IS A LOW ALREADY GAINING
STRENGTH OUT BETWEEN 130W AND 140W NEAR 40N. SATELLITE TRENDS OF A
STRONGLY DEVELOPING BAROCLINIC LEAF CLOUD AND THE COLD AIR CUMULUS
NEAR ITS CENTER TESTIFY TO THE UNSEASONABLY DYNAMIC AND BAROCLINIC
CHARACTER OF THIS SYSTEM. THIS SYSTEM HAS ENTRAINED MOISTURE FROM
TROPICAL SYSTEMS THAT HAD BEEN OUT AROUND THE HAWAIIAN ISLANDS. THE
MODELS CONTINUE TO LIFT THIS SYSTEM NORTH THROUGH OUR FORECAST AREA
AFTER MIDNIGHT TONIGHT AND ON SATURDAY MORNING. THE STRONG SURFACE
LOW WILL TRACK NORTHWARD JUST OFF THE COAST...POSSIBLY DEEPENING AS
LOW AS 990 MB OR PERHAPS A BIT LOWER. THE WINDS MAY START NEAR THE
CENTRAL COAST AROUND 12Z SATURDAY THEN MOVE NORTHWARD ALONG THE COAST
THROUGH THE MORNING...WITH THE GRADIENT FINALLY EASING BETWEEN 18Z
AND 21Z ON SATURDAY...THAT IS 11 AM TO 2 PM. ALSO LOOK FOR BRISK
WINDS IN THE VALLEYS AS WELL. THERE WILL BE A SURGE IN RAIN AS
WELL...BUT OFTEN THE RAIN IS NOT QUITE AS HEAVY AS YOU MIGHT EXPECT
WITH THESE WIND STORMS.

THE PRECIPITATION WILL TURN TO SHOWERS AND DECREASE BY AFTERNOON...
BUT THE NEXT FRONT CURRENTLY ALONG 50N/135W WILL REACH THE COAST LATE
SATURDAY AND SWING THROUGH THE AREA SATURDAY NIGHT. THE MODELS ARE
FORECASTING A DECENT RAIN WITH THIS SYSTEM AS WELL AS PRETTY BREEZY
CONDITIONS...POSSIBLY CLOSE TO GALES AGAIN AT THE COAST. THIS SYSTEM
HAS SOME TROPICAL MOISTURE FROM ONE OF THE WESTERN PACIFIC TYPHOONS
IN IT.

THE PRECIPITATION WILL TURN TO SHOWERS ON SUNDAY WITH DECENT ONSHORE
FLOW. TOLLESON

.LONG TERM...NO SIGNIFICANT CHANGES. PREVIOUS DISCUSSION
FOLLOWS...SUNDAY NIGHT THROUGH THURSDAY. FALL-LIKE WEATHER PATTERN
CONTINUES INTO NEXT WEEK WITH PRIMARILY COOLER THAN NORMAL
TEMPERATURES...CLOUDY CONDITIONS...AND CHANCES FOR ADDITIONAL RAIN.
ON MONDAY A SHORTWAVE MOVING THROUGH TO OUR NORTH MAY CLIP US WITH
SOME RAIN MAINLY ON THE COAST AND INLAND NORTH WHILE THE REST OF THE
AREA SHOULD REMAIN MOSTLY DRY. HAVE LEFT A SLIGHT CHANCE FOR RAIN
ACROSS MOST OF THE AREA JUST IN CASE THE MODELS DON`T QUITE HAVE THE
RIGHT TRACK FOR THIS SHORTWAVE SINCE IT`S A FEW DAYS OUT. MODELS ARE
HONING IN ON ANOTHER LOW PRESSURE SYSTEM THAT WILL MOVE THROUGH
TUESDAY NIGHT INTO WEDNESDAY WHICH COULD PRODUCE ANOTHER SOAKING RAIN
ACROSS THE AREA. BEHIND THIS SYSTEM TEMPERATURES COOL DOWN A BIT MORE
WITH MAYBE A FEW SHOWERS LINGERING INTO THURSDAY. -MCCOY
&&

.AVIATION...CONSIDERABLE CLOUDS ACROSS THE REGION. GENERALLY MVFR
WITH AREAS OF IFR CIGS ALONG THE COAST THROUGH THE DAY TODAY.
INLAND...CIGS GENERALLY VFR THIS MORNING WITH OCCASIONAL DROPS TO
MVFR WITH CIGS AROUND FL025. INLAND TAF SITES SHOULD CONTINUE TO BE A
MIX OF VFR/MVFR THROUGH EARLY THIS EVENING. AFTER 06Z TONIGHT... RAIN
WILL INCREASE ACROSS THE AREA WITH MORE WIDESPREAD MVFR CIGS INLAND
AND IFR CIGS ALONG THE COAST.

KPDX AND APPROACHES...VFR THIS MORNING WITH CONSIDERABLE MID AND HIGH
CLOUDS. CIGS WILL LOWER TO LOW VFR LATER THIS MORNING AND
OCCASIONALLY DROP TO MVFR THROUGH THE DAY TODAY WITH OCCASIONAL RAIN.
CIGS WILL LOWER TO 2500 FT AFTER 06Z THIS EVENING WITH RAIN
INCREASING. -MCCOY
&&

.MARINE...STALLED FRONTAL BOUNDARY JUST OFFSHORE TODAY. AS ANOTHER
LOW FORMING TO THE SW MOVES NE TONIGHT THROUGH SATURDAY...SOUTHERLY
WINDS INCREASE TO 25 TO 35 KT ON THE CENTRAL OREGON COASTAL WATERS
AFTER 3AM SAT. THESE WINDS SPREAD NORTHWARD THROUGH SATURDAY MORNING
AS THE FRONT STARTS TO MOVE TOWARD SHORE. THERE IS MODERATE POTENTIAL
FOR GUSTS TO 45 KT...ESPECIALLY CLOSE TO SHORE. SEAS AROUND 4 TO 5 FT
TODAY WILL RAPIDLY BUILD AS THE WIND RAMPS UP LATE TONIGHT...WITH
SEAS OF 12 TO 15 FT EARLY SATURDAY. SOUTHERLY WINDS START TO DECREASE
SATURDAY AFTERNOON BUT STAY UP AROUND 20 TO 25 KT UNTIL SUNDAY
MORNING. SEAS STAY UP AROUND 10 TO 12 FT UNTIL SUNDAY MORNING AS
WELL...WHEN SEAS FALL TO 7 TO 9 FT. UNSETTLED WEATHER CONTINUES INTO
NEXT WEEK WITH SEAS STAYING UP AROUND 7 TO 9 FT THROUGH AT LEAST
MIDWEEK. -MCCOY/ROCKEY
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WATCH FROM LATE TONIGHT THROUGH SATURDAY AFTERNOON
     FOR NORTH OREGON COAST.

     HIGH WIND WATCH FROM LATE TONIGHT THROUGH SATURDAY AFTERNOON
     FOR CENTRAL COAST RANGE OF WESTERN OREGON-COAST RANGE OF
     NORTHWEST OREGON.

     HIGH WIND WATCH FROM LATE TONIGHT THROUGH SATURDAY MORNING FOR
     CENTRAL OREGON COAST.

WA...HIGH WIND WATCH FROM LATE TONIGHT THROUGH SATURDAY AFTERNOON
     FOR SOUTH WASHINGTON COAST.

     HIGH WIND WATCH FROM LATE TONIGHT THROUGH SATURDAY AFTERNOON
     FOR WILLAPA HILLS.

PZ...GALE WARNING FROM 3 AM SATURDAY TO MIDNIGHT PDT SATURDAY NIGHT
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA 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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