155
FXUS66 KPQR 091654 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
954 AM PDT WED SEP 9 2026
UPDATED AVIATION DISCUSSION
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 18Z THURSDAY
HIGH PRESSURE OVER THE REGION
WILL CONTINUE TO SUPPORT WIDESPREAD VFR CONDITIONS ACROSS THE
AIRSPACE BENEATH LARGELY CLEAR SKIES. LIGHT NORTH/NORTHEAST FLOW
FOR INLAND LOCATIONS WITH NORTHERLY WINDS FOR THE COAST LESS THAN
10 KT THROUGH THE TAF PERIOD. EXPECT WIDESPREAD VFR UNDER MOSTLY
CLEAR SKIES FOR ALL INLAND LOCATIONS THROUGH THE TAF PERIOD.
COOL AND MOIST ONSHORE FLOW RETURNS AROUND 03Z-06Z THURSDAY, WHICH
WILL BRING MORE NORTH/NORTHWEST WINDS ACROSS THE AIRSPACE, BUT
STILL LESS THAN 10 KT. THIS PATTERN CHANGE WILL BRING THE RETURN
OF MVFR TO LIFR CONDITIONS TO THE COAST STARTING AROUND 06Z-09Z
THURSDAY. EXPECT THESE LOWERED FLIGHT CONDITIONS TO IMPACT KAST
FIRST, FOLLOWED BY KONP. ALSO, LOOK FOR PREDOMINATELY IFR/LIFR
CONDITIONS ALONG THE COAST STARTING AROUND 08Z THURSDAY FOR KAST
AND 13Z THURSDAY FOR KONP. ANY LOWERED FLIGHT CONDITIONS SHOULD
START TO IMPROVE AROUND 18Z THURSDAY.
KPDX AND APPROACHES...VFR UNDER MOSTLY CLEAR SKIES WITH LIGHT
NORTHERLY WINDS THROUGH THE TAF PERIOD PERIOD. /42
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...NONE.
WWW.WEATHER.GOV/PORTLAND
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