Area Forecast Discussion
Issued by NWS Portland, OR

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000
FXUS66 KPQR 301049 AAA
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
347 AM PDT THU JUL 30 2015

.SYNOPSIS...STRONG UPPER LEVEL HIGH PRESSURE WILL BRING THE HOTTEST
DAY OF THE SUMMER AND LIKELY IN THE PAST SEVERAL YEARS. FRIDAY WILL
BE SIMILAR WITH ONLY GRADUAL COOLING EXPECTED THROUGH THE WEEKEND AND
THE START OF NEXT WEEK.


&&


.SHORT TERM...TODAY THROUGH SUNDAY...HOT.

FOG PRODUCT EARLY THIS MORNING REVEALS CLEAR SKIES ACROSS THE ENTIRE
FORECAST AREA. THE 00Z KSLE SOUNDING RECORDED 21C AT 850MB...AND IS
PROJECTED TO WARM INTO THE 23 TO 25C RANGE TODAY. THIS WILL PUSH THE
WARMEST 850MB RECORDED AT KSLE ON THIS DATE. THE WARMING
TEMPERATURES ALOFT SHOULD TRANSLATE INTO MOST LOCATIONS IN THE
WILLAMETTE VALLEY WARMING 3 TO 5 DEGREES TODAY RELATIVE TO
WEDNESDAY. WEAK ONSHORE FLOW AT THE SURFACE WILL CONTINUE
TODAY...WHICH SHOULD LIMIT TEMPERATURES ALONG THE LOWER COLUMBIA
RIVER RELATIVE TO AREAS FARTHER SOUTH IN THE WILLAMETTE VALLEY. MOS
GUIDANCE HANDLED YESTERDAY WELL...BUT BRINGS FORECAST HIGH
TEMPERATURES TO LEVELS THAT ARE A BIT DISCONCERTING GIVEN WE ARE ON
THE EDGE OF CLIMATOLOGY...A TIME WHEN MOS GUIDANCE CAN UNDER DO
TEMPERATURES. THE MAV...MET..AND MEX GUIDANCE ALL SUGGEST THE
CENTRAL AND SOUTHERN WILLAMETTE VALLEY MAY SEE ONE OF THEIR WARMEST
DAYS ON RECORD WITH EVEN THE PDX METRO RISING TO 100F OR SLIGHTLY
ABOVE. GIVEN THE CONSENSUS...TEMPERATURES WERE INCREASED SEVERAL
DEGREES AND AS A RESULT...OPTED TO UPGRADE THE HEAT ADVISORY TO AN
EXCESSIVE HEAT WARNING. WE OPTED TO INCLUDE THE PORTLAND METRO AND
COLUMBIA RIVER GORGE ZONES IN THE WARNING EVEN THOUGH TEMPERATURES
WILL BE SEVERAL DEGREES COOLER THAN THE CENTRAL AND SOUTHERN
WILLAMETTE VALLEY. THE BOTTOM LINE IS THAT IT WILL BE THE HOTTEST
DAY SO FAR THIS SUMMER...AND FOR THAT MATTER...PROBABLY IN THE LAST
SEVERAL YEARS AT MANY LOCATIONS.

ONSHORE FLOW DOES INCREASE EVER SO SLIGHTLY FRIDAY SO TEMPERATURES
STILL LOOK TO COOL A COUPLE DEGREES ON FRIDAY...BUT NOT ENOUGH THAT
VERY MANY WILL NOTICE. INCREASING CLOUD COVER AND ONSHORE FLOW OVER
THE WEEKEND SHOULD ALLOW HIGH TEMPERATURES TO COOL SEVERAL MORE
DEGREES EACH DAY. TEMPERATURES WILL REMAIN WARMEST ACROSS THE
SOUTHERN HALF OF THE WILLAMETTE VALLEY AND IN THE CENTRAL COLUMBIA
RIVER GORGE THROUGH THE WEEKEND DUE TO THESE LOCATIONS REMAINING THE
MOST REMOVED FROM THE COOLER MARINE AIR FILTERING UP THE LOWER
COLUMBIA RIVER VALLEY. AS A RESULT...MID TO UPPER 90S MAY STILL BE
PLAGUING THESE AREAS THROUGH THE WEEKEND. /NEUMAN


&&


.LONG TERM...SUNDAY NIGHT THROUGH WEDNESDAY...MODELS GENERALLY AGREE
THE AREA WILL EXPERIENCE A COOLING TREND THROUGH MIDWEEK AS 500MB
HEIGHTS LOWER AND WE RETURN TO A MORE TYPICAL NORTHWESTERLY FLOW
PATTERN. THIS SHOULD RESULT IN MORNING CLOUDS INCREASING ALONG THE
COAST AND IN THE LOWER COLUMBIA RIVER VALLEY.

DIFFERENCES CONTINUE IN THE TIMING AND AMPLITUDE OF AN INCOMING
TROUGH TOWARDS THE MIDDLE TO END OF NEXT WEEK. THERE IS A CHANCE
SOME MID TO UPPER LEVEL MOISTURE AND INSTABILITY AHEAD OF THIS
FEATURE COULD TRIGGER SOME SHOWERS AND THUNDERSTORMS...PARTICULARLY
OVER THE CASCADES EARLY NEXT WEEK...BUT CONFIDENCE REMAINS LOW. THE
INHERITED FORECAST CAPTURED THIS WELL SO FEW CHANGES WERE MADE.
/NEUMAN


&&


.FIRE WEATHER (PREVIOUS DISCUSSION)...A THERMAL TROUGH IS EXTENDING
FROM SOUTHERN OREGON INTO THE NORTH OREGON CASCADES THIS AFTERNOON.
EXPECT THIS TROUGH TO REMAIN OVER THE REGION THROUGH AT LEAST
FRI...DRIFTING BACK TOWARD THE COAST EACH NIGHT AND MOVING INLAND
DURING THE DAY AS THE INTERIOR HEATS UP. THIS PATTERN WILL BRING
ENHANCED MIXING AND INSTABILITY...WHICH COMBINED WITH THE VERY HOT
AND DRY WEATHER AND DRY FUELS WILL CREATE CRITICAL FIRE WEATHER
CONDITIONS. BASED ON THE LATEST MODEL GUIDANCE...DECIDED TO EXTEND
THE RED FLAG WARNING THROUGH FRIDAY AND TO INCLUDE THE CENTRAL OREGON
COAST RANGE...THE SOUTHERN WASHINGTON CASCADES...AND ALL OF THE
INTERIOR LOWLANDS. THE THERMAL TROUGH IS MODELED TO FINALLY PUSH EAST
OF THE CASCADES ON SAT...ALTHOUGH THE TIMING OF THIS IS STILL
SOMEWHAT UNCERTAIN. PYLE


&&


.AVIATION...VFR CONDITIONS EXPECTED TO CONTINUE THROUGHOUT NW OREGON
AND SW WA THROUGH THU NIGHT.

KPDX AND APPROACHES...VFR CONDITIONS FOR THE NEXT 24 HRS.


&&


.MARINE...STEEP SEAS CONTINUED EARLY THIS MORNING...MAINLY ACROSS
THE SOUTHERN WATERS...AS WIND WAVES AND FRESH SWELL DOMINATED THE
WAVES. OVER THE NEXT FEW DAYS HIGH PRES WILL REMAIN OVER THE NE
PACIFIC CENTERED ROUGHLY OFF THE WA COAST. A TROUGH OF LOW PRES
ALONG THE OREGON COAST THIS MORNING IS EXPECTED TO MOVE INLAND LATER
TODAY. THIS WILL KEEP N TO NW WINDS BLOWING OVER THE WATERS THROUGH
THE WEEKEND...WITH A CLIMATOLOGICAL TENDENCY TO STRENGTHEN IN THE
LATE AFTERNOON AND OVERNIGHT HOURS AND WEAKEN IN THE MORNING HOURS
EACH DAY. EXPECT TO SEE WINDS GUSTING INTO SMALL CRAFT RANGE OFF AND
ON THROUGH THE WEEKEND. THE STEEP SEAS ARE LIKELY TO SUBSIDE A
LITTLE THIS MORNING AS WINDS BACK OFF SOME IN THE MORNING...SO WILL
ALLOW THE SMALL CRAFT FOR HAZARDOUS SEAS TO EXPIRE THIS MORNING.
WITH SEAS REMAINING DOMINATED BY WIND WAVES AND FRESH SWELL NEXT FEW
DAYS...MAY STILL NEED TO ISSUE SMALL CRAFTS FOR HAZARDOUS SEAS AGAIN
LATER TODAY OR IN THE NEXT FEW DAYS.


&&


.PQR WATCHES/WARNINGS/ADVISORIES...
OR...EXCESSIVE HEAT WARNING FROM NOON TODAY TO 9 PM PDT FRIDAY FOR
     CENTRAL COLUMBIA RIVER GORGE-CENTRAL WILLAMETTE VALLEY-
     GREATER PORTLAND METRO AREA-SOUTH WILLAMETTE VALLEY-UPPER
     HOOD RIVER VALLEY-WESTERN COLUMBIA RIVER GORGE.

     RED FLAG WARNING UNTIL 11 PM PDT FRIDAY FOR ZONE 603-ZONE 604-
     ZONE 605-ZONE 606-ZONE 607-ZONE 608.

     HEAT ADVISORY UNTIL 9 PM PDT FRIDAY FOR CASCADE FOOTHILLS IN
     LANE COUNTY-CENTRAL COAST RANGE OF WESTERN OREGON-COAST
     RANGE OF NORTHWEST OREGON-LOWER COLUMBIA-NORTHERN OREGON
     CASCADE FOOTHILLS.

WA...EXCESSIVE HEAT WARNING FROM NOON TODAY TO 9 PM PDT FRIDAY FOR
     CENTRAL COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-WESTERN
     COLUMBIA RIVER GORGE.

     RED FLAG WARNING UNTIL 11 PM PDT FRIDAY FOR ZONE 604-ZONE 660.

     HEAT ADVISORY UNTIL 9 PM PDT FRIDAY FOR I-5 CORRIDOR IN COWLITZ
     COUNTY.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 3 AM PDT FRIDAY FOR
    COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM PDT EARLY
     THIS MORNING FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
    CASCADE HEAD OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL NOON PDT TODAY
    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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