Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 302114
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
214 PM PDT SUN AUG 30 2015

.SYNOPSIS...SHOWERS WILL DECREASE THIS EVENING AS AN UPPER LEVEL
SHORTWAVE MOVES FURTHER INLAND. A WARM FRONT WILL BRING LIGHT RAIN TO
THE COAST AND NORTHERN AREAS MONDAY....FOLLOWED BY A WEAK COLD FRONT
MORE WIDESPREAD RAIN ON TUESDAY. AN UPPER LEVEL TROUGH WILL
CONTINUED COOL AND SHOWERY WEATHER THROUGH THURSDAY....AND POSSIBLY
FRIDAY. HIGH PRESSURE WITH DRIER AND WARMER WEATHER EXPECTED FOR NEXT
WEEKEND.

&&

.SHORT TERM...TONIGHT THROUGH WEDNESDAY...A SERIES OF UPPER LEVEL
SHORTWAVES ROTATING AROUND A BROAD UPPER TROUGH OVER THE PACIFIC NW
AND THE NE PACIFIC WILL RESULT IN COOL AND SHOWERY WEATHER FOR THE
PORTLAND FORECAST AREA MOST OF THE WORK WEEK. POST-FRONTAL SHOWERS
CONTINUE ACROSS THE REGION EARLY THIS AFTERNOON...MAINLY OVER THE
CASCADES AND CASCADE FOOTHILLS AS AN UPPER LEVEL TROUGH MOVES OVER
THE REGION. SHOWERS WILL REMAIN OVER THE CASCADES THROUGH EARLY THIS
EVENING...AND DECREASE WEST OF THE CASCADES. SOME OF THESE SHOWERS
HAVE BEEN PRODUCING HEAVY BRIEF DOWNPOURS.

SATELLITE IMAGERY SHOWS THE NEXT FRONTAL SYSTEM APPROACHING THE
WASHINGTON AND OREGON COAST. THE SURFACE LOW ASSOCIATED WITH THIS
SYSTEM IS CURRENTLY NEAR 52N 132W...JUST OFF THE B.C. COAST. A WEAK
WARM FRONT WILL MOVE ACROSS SW WASHINGTON AND EXTREME NW OREGON LATE
TONIGHT THROUGH MONDAY AFTERNOON AND DISINTEGRATE OVER THE AREA LATE
MONDAY AFTERNOON. LIGHT RAIN IS EXPECTED FOR SW WASHINGTON...THE
NORTH OREGON COAST...AND THE NORTH OREGON COAST RANGE. THERE MAY BE A
FEW SHOWERS ALONG THE CENTRAL OREGON COAST AND COAST RANGE AS WELL.
RAINFALL TOTALS WILL BE LIGHT WITH 24 HOUR TOTALS LESS THAN 0.25
INCH.

MONDAY WILL BE THE WARMEST DAY OF THE WEEK DUE TO WARM AIR ADVECTION
WITH THE WARM FRONT. SOUTHERN AREAS WILL BE THE WARMEST SINCE THEY
WILL NOT LIKELY SEE MUCH IMPACTS FROM THE FRONT...AND MAY HAVE MORE
SOLAR HEATING. EXPECT TEMPERATURES FOR THE WILLAMETTE VALLEY TO PEAK
IN THE MID TO UPPER 70S...WITH NORTHERN AND COASTAL TEMPS PEAKING IN
THE MID 60S. THE COLUMBIA GORGE AND UPPER HOOD RIVER VALLEY WILL ALSO
SEE TEMPERATURES WARMING INTO THE UPPER 70S.

THE TRAILING COLD FRONT WILL SPREAD MORE WIDESPREAD LIGHT RAIN
TUESDAY....AGAIN WITH 24 HOUR RAINFALL TOTALS LESS THEN 0.25 INCH.
COOLER AIR BEHIND THIS FRONT WILL LOWER SNOW LEVELS DOWN TO AROUND
6500 FEET LATE TUESDAY NIGHT AS A STRONG UPPER TROUGH MOVES OVER THE
AREA...POSSIBLY WITH ANOTHER SURFACE FRONT. THE TROUGH WILL PRODUCE
ADDITIONAL SHOWERS ACROSS THE AREA LATE TUESDAY NIGHT THROUGH
WEDNESDAY AFTERNOON.

DAYTIME HIGHS IN THE INTERIOR LOW LANDS WILL PEAK IN THE LOW 70S ON
TUESDAY AND JUST AROUND 70 ON WEDNESDAY.TJ

.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY. THE UPPER LEVEL TROUGH
AXIS WILL REMAIN NEAR THE COAST LATE WEDNESDAY INTO THURSDAY AND
TRIES TO SLIDE EASTWARD...THOUGH MODELS SUGGEST THIS WILL BE SLOW TO
OCCUR AS A FEW SHORTWAVES ON THE BACK SIDE OF THE TROUGH MAY SLOW
THE PROGRESS AS THE TROUGH SLIDES A BIT SOUTH. THIS WILL BRING
CONTINUED COOL...AND AT TIMES SHOWERY...CONDITIONS TO THE REGION FOR
THURSDAY AND FRIDAY...WITH THE BASE OF THE TROUGH OVERHEAD FRIDAY
BEFORE SHIFTING EAST OF THE CASCADES. HEIGHTS LOOK TO RISE A BIT FOR
THE WEEKEND FOR DRY AND WARMER WEATHER...PERHAPS BACK TO NEAR
SEASONAL NORMALS FOR SUNDAY.   CULLEN
&&

.AVIATION...ISOLATED SHOWERS...MAINLY NORTH OF KMMV...WILL
CONTINUE TO DEVELOP OVER THE INTERIOR THROUGH THIS EVENING.
HEAVIER SHOWERS COULD BRING BRIEF PERIODS OF MVFR CIGS AND VSBY
THROUGH AROUND 08Z. OTHERWISE...EXPECT MOSTLY VFR CONDITIONS
ACROSS THE INTERIOR THE NEXT 24 HOURS.

CONDITIONS CURRENTLY VFR ALONG THE COAST. MARINE STRATUS LOOKS TO
RETURN TONIGHT AND WILL LIKELY BRING MVFR CIGS AND VSBY AFTER 06Z.
PERIODS OF IFR CIGS AND VSBY ALSO POSSIBLE LATE TONIGHT...MAINLY
SOUTH OF KTMK. CONDITIONS MAY IMPROVE TOWARDS VFR MONDAY
AFTERNOON...BUT CONFIDENCE REMAINS LOW.

KPDX AND APPROACHES...VFR THE NEXT 24 HOURS. SCATTERED SHOWERS
WILL CONTINUE THROUGH AROUND 08Z AND COULD BRING BRIEF PERIODS OF
MVFR CIGS AND VSBY. /64

&&

.MARINE...A WEAK DISTURBANCE WILL MOVE ACROSS THE NORTHERN WATERS
THIS EVENING FOLLOWED BY ANOTHER DISTURBANCE MONDAY MORNING.
EXPECT SCA GUSTS OF 25 KT TO DEVELOP THIS EVENING AND CONTINUE
THROUGH MONDAY. WILL KEEP THE SCA FOR WINDS AS IS...BUT SUSPECT WE
MAY BE ABLE TO DROP IT MONDAY MORNING.

A FRESH SWELL CONTINUES TO BRING SQUARE SEAS TO THE WATERS THIS
AFTERNOON. BUOY 46050 CONTINUES TO SHOW SEAS AROUND 8 FT AT 8
SECONDS WHILE BUOY 46089 CURRENTLY SHOWING 11 FT SEAS AT 13
SECONDS. SUSPECT THAT THE LONGER PERIOD SWELL WILL BECOME THE
DOMINATE PERIOD THIS EVENING. WILL KEEP THE CURRENT SCA FOR
HAZARDOUS SEAS AS IS...BUT WILL NEED TO MONITOR CONDITIONS AND
REEVALUATE WITH THE EVENING UPDATE.

AN UNSETTLED PATTERN CONTINUES THROUGH THE UPCOMING WEEK WITH
PERIODS OF SCA WINDS TO 25 KT POSSIBLE AS ADDITIONAL WEAK
DISTURBANCE MOVE ACROSS THE WATERS. SEAS LOOK TO REMAIN AROUND 7
TO 10 FT THROUGH THE WEEK. A RETURN TO THE TYPICAL SUMMERTIME
PATTERN POSSIBLE LATE NEXT WEEK. /64

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 7 PM THIS EVENING TO 6 PM
     PDT MONDAY FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
     CASCADE HEAD OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 PM PDT THIS
     EVENING FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
     FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL
     10 PM PDT THIS EVENING...AND FROM 4 AM TO 9 AM PDT MONDAY.

&&

$$

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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