691
FXUS66 KPQR 090920
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
220 AM PDT WED SEP 9 2026
SYNOPSIS
DRY AND WARMER CONDITIONS PERSIST THROUGH THURSDAY
WITH WEAK ONSHORE FLOW CONTINUING THROUGH WEDNESDAY. COOLER
TEMPERATURES RETURN FOR FRIDAY THROUGH THE WEEKEND. RAIN RETURNS
TO THE AREA ON SATURDAY WITH SHOWER CHANCES CONTINUING OVER THE
CASCADES ON SUNDAY. RATHER BENIGN, DRY WEATHER RETURNS EARLY
NEXT WEEK.
DISCUSSION...WEDNESDAY MORNING THROUGH TUESDAY
SURFACE
OBSERVATIONS AND SATELLITE IMAGERY INDICATE CLEAR SKIES ACROSS
THE MAJORITY OF NW OR AND SW WA EARLY WEDNESDAY MORNING WITH
LOCALIZED FOG DEVELOPING IN SHELTERED VALLEYS. HIGH PRESSURE
OVER THE SOUTHERN US WILL BRIEFLY SPREAD NORTH INTO THE PACNW
TODAY, PRODUCING ANOTHER SUNNY AND DRY DAY WITH HIGH
TEMPERATURES WARMING A FEW DEGREES FROM YESTERDAY FOR MOST
LOCATIONS, INCLUDING THE COAST WHERE OFFSHORE FLOW (WINDS FROM
THE EAST) THROUGH MIDDAY WILL LIKELY ENHANCE WARMING. EXPECT
HIGHS IN THE MID TO UPPER 80S FOR THE INTERIOR LOWLANDS, 70S TO
LOW 80S FOR THE TERRAIN, AND UPPER 60S TO MID 70S ALONG THE
COAST.
ENSEMBLE GUIDANCE IS NOW IN VERY GOOD AGREEMENT ON THE WEATHER
PATTERN THROUGH THE WEEKEND. A WEAK TROUGH WILL DEEPEN INTO THE
PACNW LATE WEDNESDAY INTO THURSDAY, PUSHING SOUTH THE HIGH
PRESSURE. EXPECT HIGH TEMPERATURES TO LOWER ANYWHERE FROM 3-10
DEGREES FROM TODAY'S HIGHS, THOUGH DRY WEATHER REMAINS.
A STRONGER CLOSED LOW PRESSURE SYSTEM DEVELOPS ALONG THE
WESTERN CANADA BORDER LATE THURSDAY AND MOVES SOUTH ALONG THE
COAST INTO THE PACNW THROUGH SATURDAY, THEN PUSHING INLAND TO
THE EAST SUNDAY. THIS WEATHER SYSTEM WILL BRING A ROUND OF RAIN
TO THE AREA THROUGH THE DAY ON SATURDAY WITH SHOWER CHANCES
CONTINUING OVER THE CASCADES THROUGH SUNDAY AFTERNOON. THERE'S A
50-70% CHANCE OF LOCATIONS WEST OF THE CASCADES RECEIVING AT
LEAST 0.25 INCH OF RAIN WITH A 65-85% CHANCE FOR THE CASCADES.
FOR CHANCES OF AT LEAST 0.5 INCH OF RAIN, THOSE LOWER TO
15-30% WEST OF THE CASCADES AND 40-65% FOR THE CASCADES. NOT A
SOAKER BY ANY MEANS, BUT A NICE ROUND OF STEADY RAIN TO BREAK UP
THE WARM AND DRY CONDITIONS. ONE NOTE IS THE HOOD RIVER VALLEY
MAY BE RAIN SHADOWED DUE TO THE WESTERLY NATURE OF THIS WEATHER
SYSTEM, WITH ONLY A 25-40% CHANCE OF RECEIVING 0.25 INCH OF
RAIN. THIS WEATHER SYSTEM WILL ALSO BRING EVEN COOLER
TEMPERATURES ON SATURDAY WITH HIGHS FORECAST IN THE LOW TO MID
60S ACROSS THE INTERIOR LOWLANDS AND COAST WITH 40S TO 50S OVER
THE TERRAIN. TEMPERATURES ARE FORECAST TO WARM ROUGHLY 5 DEGREES
FOR MOST INLAND LOCATIONS ON SUNDAY, THOUGH WILL STILL BE ON THE
COOLER SIDE OF NORMAL (WHICH IS THE UPPER 70S FOR THE INTERIOR
LOWLANDS IN MID SEPTEMBER).
AS THE MAIN WEATHER SYSTEM MOVES TO THE EAST EARLY NEXT WEEK,
RATHER BENIGN WEATHER TAKES HOLD OF THE AREA MONDAY AND TUESDAY.
DRY CONDITIONS ARE EXPECTED TO RETURN, THOUGH UNCERTAINTY
REMAINS IN TEMPERATURES AS SOME ENSEMBLE MEMBERS SUGGEST WEAK
LONGWAVE TROUGHING SETTLES IN PLACE OVER THE PACNW, WHICH WOULD
KEEP TEMPERATURES ON THE COOLER THAN NORMAL SIDE, WHILE OTHERS
INDICATE MORE ZONAL FLOW OR SLIGHT RIDGING, WHICH WOULD ALLOW
TEMPERATURES TO RISE TO NEAR OR A BIT HIGHER THAN NORMAL.
WHICHEVER PATTERN WINS OUT, NO IMPACTS ARE EXPECTED AT THIS
TIME. -03
AVIATION...THROUGH 12Z THURSDAY
HIGH PRESSURE OVER THE REGION
WILL CONTINUE TO SUPPORT WIDESPREAD VFR CONDITIONS ACROSS THE
AIRSPACE BENEATH LARGELY CLEAR SKIES. LIGHT OFFSHORE FLOW INTO
WEDNESDAY MORNING WILL LIMIT CHANCES FOR LOW CIGS TO AROUND 20%
ALONG THE COAST, BUT IF EAST WINDS ARE LIGHTER THAN EXPECTED,
LOWERED CIGS WILL BE MORE LIKELY. FAVORED EAST-SOUTHEAST WINDS
ALONG YOUNGS BAY AT KAST MAY ALSO RESULT IN RESTRICTED VIS WITHIN
FOG/MIST OVERNIGHT DESPITE THE OFFSHORE ORIENTATION, HOWEVER
CONFIDENCE IN OCCURRENCE IS LOW. NORTH TO NORTHWEST WINDS BUILD TO
5-10 KT INLAND AND 8-12 KT WITH GUSTS TO 20 KT ALONG THE COAST BY
18-20Z WED WITH HIGH CONFIDENCE IN WIDESPREAD VFR CONDITIONS.
ONSHORE FLOW RETURNS ALONG THE COAST WITH THE NORTHWEST WINDS
WEDNESDAY AFTERNOON AND WILL CONTINUE THROUGH WEDNESDAY NIGHT,
EVEN AS WINDS DECREASE AFTER 03Z THU. THIS WILL ALLOW FOR THE
RETURN OF MARINE STRATUS ALONG THE COAST, DEVELOPING ALONG THE
COAST AFTER 06-09Z THU.
KPDX AND APPROACHES...VFR CONDITIONS EXPECTED THROUGH THE PERIOD.
DIURNAL NORTHWEST WINDS AT 3-5 KT OVERNIGHT WILL BUILD TO 6-8 KT
BY 18-20Z WED, DECREASING AGAIN BY 03-06Z THU. HIGH CLOUD
COVERAGE INCREASES AFTER 06Z THU. -03/36
MARINE
HIGH PRESSURE OFFSHORE WILL MAINTAIN PREDOMINATELY
NORTHERLY WINDS ACROSS THE COASTAL WATERS THROUGH THE WEEK. THE
PRESSURE GRADIENT OVER THE WATERS IS SLOWLY DECREASING, AND GUSTS
UP TO 25 KTS ARE EXPECTED TO CONTINUE FOR THE OUTER COASTAL WATERS
THROUGH 6 AM WEDNESDAY. BREEZY NORTH WINDS CONTINUE THROUGH
THURSDAY, BUT SHOULD REMAIN 20 KT OR LESS. SEAS HAVE BUILT TO
AROUND 6 TO 7 FT WEDNESDAY MORNING WITH A DOMINANT NORTHWEST
SWELL AT 14 TO 15 SECONDS BEHIND THE STRONGER NORTHERLY WINDS FROM
YESTERDAY. SEAS REMAINS AROUND 6 TO 7 FT THROUGH THURSDAY WITH
PERIOD LOWERING TO 10-11 SECONDS BY THIS EVENING. A WEAK LOW
PRESSURE SYSTEM WILL MOVE THROUGH THE WATERS THURSDAY NIGHT,
BRIEFLY ELEVATING SEAS TO 7 TO 8 FT AT 10 SECONDS THURSDAY
AFTERNOON AND NIGHT AS WINDS INCREASE SLIGHTLY AHEAD OF THE
SYSTEM. ANOTHER WEAKER IS EXPECTED TO APPROACH THE COASTAL WATERS
FROM THE NORTH LATE FRIDAY INTO SATURDAY, THOUGH SEAS ARE FORECAST
TO REMAIN AROUND 5 TO 6 FT AND WIND GUSTS BELOW 20 KTS WITH THIS
SYSTEM. -03
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 6 AM PDT EARLY THIS MORNING FOR
PZZ272-273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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