305
FXUS66 KPQR 030610
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1110 PM PDT FRI OCT 2 2026
UPDATE
DENSE FOG ADVISORIES HAVE BEEN ISSUED FOR THE NORTH
AND CENTRAL OREGON COAST AND THE SOUTH WASHINGTON COAST UNTIL 10
AM PDT SATURDAY, AND ACROSS THE COASTAL WATERS FROM FLORENCE TO
CAPE SHOALWATER INCLUDING THE COLUMBIA RIVER BAR UNTIL NOON PDT
SATURDAY. REGIONAL OBSERVATIONS AND AVAILABLE CAMERAS DEPICT
INCREASING COVERAGE OF FOG WITHIN COASTAL COMMUNITIES AS HIGH
PRESSURE COMPRESSES THE MARINE LAYER, BRINGING CLOUD BASES DOWN
TO THE SURFACE. FOG WILL BREAK UP BY LATE MORNING TO MIDDAY.
SYNOPSIS
BUILDING HIGH PRESSURE WITH PERIODS OF OFFSHORE
FLOW WILL SUPPORT WARM AND DRY CONDITIONS THROUGH MUCH OF NEXT
WEEK. EARLY MORNING VALLEY FOG WILL BE LIMITED TO SHELTERED
VALLEYS, ESPECIALLY IN THE COAST RANGE.
DISCUSSION...NOW THROUGH THURSDAY
UPPER LEVEL RIDGING
CENTERED OVER THE DESERT SOUTHWEST WILL CONTINUE TO DOMINATE
CONDITIONS ACROSS THE PACNW INTO AT LEAST THE MIDDLE OF NEXT
WEEK, SUPPORTING DRY CONDITIONS AND WELL ABOVE AVERAGE
TEMPERATURES. A SHORTWAVE MOVING ALONG THE US-CANADA BORDER HAS
KEPT THE RIDGE SLIGHTLY SUPPRESSED TODAY ALONG WITH SOME CLOUD
COVER ACROSS WESTERN WA AND INTO THE FAR NORTHWESTERN PORTIONS
OF OR. DESPITE THIS, TEMPERATURES ARE STILL EXPECTED TO PEAK IN
THE UPPER 70S ACROSS THE INTERIOR LOWLANDS AND MID 60S TO LOW
70S ALONG THE COAST.
TONIGHT INTO TOMORROW, THE UPPER LEVEL TROUGH IS EXPECTED TO
AMPLIFY IN THE WAKE OF THE DEPARTING SHORTWAVE. 850 MB
TEMPERATURES ARE EXPECTED TO JUMP INTO THE 15-21 C RANGE ON
SATURDAY AND BETWEEN 17-22 C ON SUNDAY. THIS IS EXPECTED TO
TRANSLATE TO SATURDAY HIGHS IN THE UPPER 70S TO LOW 80S ACROSS
THE INTERIOR LOWLANDS AND MID 60S TO LOW 70S ALONG THE COAST.
SUNDAY HIGHS JUMP UP INTO THE LOW TO MID 80S INLAND WHILE
COASTAL AREAS SEE SIMILAR TEMPERATURES TO SATURDAY. MOST AREAS
ARE NOT EXPECTED TO REACH RECORD HIGH TEMPS, BUT THE RELATIVELY
WEAK RECORD OF 84 DEGREES AT PDX COULD BE IN JEOPARDY ON SUNDAY.
A WEAK THERMAL TROUGH IS EXPECTED TO DEVELOP ALONG THE OREGON
COAST TONIGHT WITH A MEAN PRESSURE GRADIENT BETWEEN PORTLAND
AND THE DALLES OF -2 MB AND LIKELY REMAINING LESS THAN -4 MB PER
SHORT-RANGE ENSEMBLES. THIS MAGNITUDE OF GRADIENT FAVORS A
DIURNALLY VARYING WIND WITH OFFSHORE (EASTERLY) FLOW DEVELOPING
NIGHTLY OVER THE CASCADES AND THEIR WESTERN SLOPES, AS WELL AS
POSSIBLY IN THE HIGHEST REACHES OF THE COAST RANGE, BEFORE
DAYTIME MIXING SEES WINDS DECREASE OVER TERRAIN AND INCREASE OUT
OF THE NORTH WITHIN INLAND VALLEYS. OFFSHORE WINDS LOOK TO PEAK
SATURDAY NIGHT INTO SUNDAY MORNING, WITH GUSTS OF 20-30 MPH IN
THE CASCADES AND FOOTHILLS, HIGHEST IN TYPICAL AREAS WITHIN AND
NEAR THE COLUMBIA RIVER GORGE. THIS PATTERN WILL ADDITIONALLY
PROMOTE NIGHTLY AREAS OF VALLEY FOG THANKS TO LIGHT WINDS AWAY
FROM THE CASCADES, DRY MID AND UPPER LEVELS LIMITING CLOUD
COVER, AND ROBUST NOCTURNAL INVERSIONS DURING INCREASINGLY LONG
NIGHTS. COAST RANGE VALLEYS ARE THE MOST LIKELY TO SEE AREAS OF
LIMITED VISIBILITY, BUT THE COVERAGE OF FOG ACROSS THE REGION
AND POSSIBLY INCLUDING THE WILLAMETTE VALLEY REMAINS UNCERTAIN.
BY MONDAY, CONFIDENCE REMAINS HIGH IN THE UPPER LEVEL TROUGH
AXIS SHIFTING TOWARD THE CENTER OF THE CONUS WHILE ALSO
DEAMPLIFYING, ALLOWING THE OVERALL FLOW TO TURN BACK ONSHORE
WHILE BRINGING AN END TO THE LOCALLY BREEZIER EAST WINDS.
FORECAST HIGH TEMPERATURES LOWER INTO NEXT WEEK BUT REMAIN 5-10
DEGREES ABOVE NORMAL ACROSS THE INTERIOR LOWLANDS. ENSEMBLES
SHOW GOOD AGREEMENT IN CONDITIONS REMAINING DRY THROUGH AT LEAST
THURSDAY WITH THE NEXT CHANCE FOR RAIN COMING LATE FRIDAY OR
INTO NEXT WEEKEND WITH ROUGHLY 40-60% OF MEMBERS DEPICTING LIGHT
RAIN. -19/36
AVIATION...THROUGH 06Z SUNDAY
SATELLITE IMAGERY AND TERMINAL
OBSERVATIONS AS OF LATE FRIDAY EVENING DEPICTS LOW MARINE
STRATUS ALONG THE COAST BRINGING LIFR CIGS AND IFR/LIFR VIS TO
KAST AND KONP. HIGH CONFIDENCE THAT THESE TRENDS CONTINUE
THROUGH 16-17Z SAT WITH 1/2SM FOG AT KONP. HIGH PRESSURE ALOFT
IS BUILDING, WHICH IS RESULTING IN THE MARINE LAYER BEING PUSHED
LOWER TO THE SURFACE. FOR WILLAMETTE VALLEY TERMINALS, VFR
CONDITIONS PREVAIL THROUGH THE TAF PERIOD WITH HIGH CLOUDS.
THERE IS A 15-30% CHANCE FOR MVFR STRATUS AT ANY GIVEN HOUR
BETWEEN 10-17Z SAT, BUT DUE TO LOW CONFIDENCE, MVFR CONDITIONS
WERE NOT INCLUDED IN THE TAFS. NORTHERLY TO NORTHWESTERLY WINDS
ACROSS THE REGION GENERALLY UNDER 10 KT. EASTERLY WINDS INCREASE
THROUGH THE COLUMBIA RIVER GORGE AND FAR EAST PORTLAND METRO
(KTTD), BUT REMAIN LIGHT.
KPDX AND APPROACHES...VFR WITH HIGH CLOUDS THROUGH THE TAF
PERIOD. 10-20% CHANCE FOR MVFR STRATUS AT ANY GIVEN HOUR
BETWEEN 11-16Z SAT. NORTHWESTERLY WINDS 2-6 KT. -10
MARINE
A WEAK SYSTEM MOVING TOWARDS THE US-CANADA BORDER
CONTINUES TO BRING WEST TO SOUTHWEST WINDS NORTH OF CAPE
FOULWEATHER THIS AFTERNOON. WINDS WILL SHIFT BACK TO NORTHERLY
BY TONIGHT AND WILL REMAIN IN PLACE INTO NEXT WEEK AS HIGH
PRESSURE BUILDS. SATURDAY AND SUNDAY AFTERNOON MAX WIND GUSTS
MAY EXCEED 20 KT, MOST LIKELY WITHIN 20 NM OF THE COAST. SEAS
CONTINUE AT 3 TO 6 FT THROUGH MUCH OF THE NEXT WEEK.
NORTHWESTERLY SWELL AT 8 TO 9 SECONDS WILL INCREASE TO 10 TO 12
SECONDS EARLY NEXT WEEK. ~12/36
PQR WATCHES/WARNINGS/ADVISORIES
OR...DENSE FOG ADVISORY UNTIL 10 AM PDT SATURDAY FOR ORZ101>103.
WA...DENSE FOG ADVISORY UNTIL 10 AM PDT SATURDAY FOR WAZ201.
PZ...DENSE FOG ADVISORY UNTIL NOON PDT SATURDAY FOR PZZ210-251>253-
271>273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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