659
FXUS66 KPQR 030501 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
1001 PM PDT FRI OCT 2 2026
..UPDATED AVIATION DISCUSSION
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...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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