346
FXUS66 KPQR 070854
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
154 AM PDT MON SEP 7 2026
SYNOPSIS
LINGERING RAIN SHOWERS WILL DISSIPATE BY SUNRISE
MONDAY MORNING AS AN UPPER LEVEL LOW CENTERED OVER CENTRAL OR
CONTINUES MOVING EAST OF THE CASCADES. TRENDING DRIER MONDAY
THROUGH THURSDAY WITH TEMPERATURES GRADUALLY WARMING AND PEAKING
ON WEDNESDAY WITH THE DEVELOPMENT OF LOW-LEVEL OFFSHORE FLOW.
THE FORECAST BECOMES MORE UNCERTAIN LATE FRIDAY INTO SUNDAY,
WITH THE POTENTIAL FOR WEATHER CONDITIONS TO RANGE ANYWHERE FROM
COOL AND SHOWERY TO WARM AND DRY DEPENDING ON THE EVOLUTION OF
THE LARGE SCALE WEATHER PATTERN.
DISCUSSION...MONDAY MORNING THROUGH SUNDAY
AS OF EARLY MONDAY
MORNING, THE UPPER CLOSED LOW PRESSURE SYSTEM THAT HAS BEEN
PRODUCING DAYS OF RAIN AND THUNDERSTORMS HAS FINALLY MOVED EAST
OF THE CASCADES. A FEW LINGERING SHOWERS OVER THE CASCADES
SHOULD DISSIPATE BY SUNRISE, AND A WEAK SHORTWAVE ON THE BACK
SIDE OF THE LOW MOVING THROUGH THE AREA TODAY COULD PRODUCE A
FEW STRAY SHOWERS THIS AFTERNOON OVER THE SOUTH WA/NORTH OR COST
AND WILLAPA HILLS. OTHERWISE, DRY CONDITIONS ARE EXPECTED TODAY
WITH CLEARING SKIES BY EARLY AFTERNOON AS DAYTIME HEATING BURNS
OFF ANY STRATUS THAT FORMS IN THE MORNING HOURS. DAYTIME
TEMPERATURES ARE EXPECTED TO WARM INTO THE LOW TO MID 70S
ACROSS THE INTERIOR LOWLANDS AND MID TO UPPER 60S ALONG THE
COAST.
CONFIDENCE IS HIGH FOR DRY WEATHER AND WARMER TEMPERATURES TUESDAY
THROUGH THURSDAY AS HIGH PRESSURE OVER THE FOUR CORNERS REGION
PUSHES NORTHWEST INTO OREGON. A SURFACE THERMAL TROUGH PUSHING
NORTH FROM NORTHERN CA WILL ALLOW FOR WEAK LOW- LEVEL OFFSHORE
FLOW TO DEVELOP. MOST INLAND VALLEY LOCATIONS WILL SEE HIGH
TEMPERATURES IN THE UPPER 70S TO MID 80S EACH DAY, WARMEST ON
WEDNESDAY. THE COAST WILL REMAIN A BIT COOLER WITH HIGHS MOST
LIKELY IN THE LOW TO MID 70S. THAT SAID, EVEN THE COAST HAS A
1-15% CHANCE OF REACHING 80 DEGREES OR WARMER, SPECIFICALLY ON
WEDNESDAY WHEN OFFSHORE WINDS HAVE THE POTENTIAL TO LAST INTO
THE EARLY AFTERNOON.
ALTHOUGH CONFIDENCE HAS INCREASED FOR DRY AND WARM WEATHER ON
THURSDAY, CONFIDENCE REMAINS RELATIVELY LOWER LATE FRIDAY INTO
SATURDAY. THIS IS DUE TO MODEL DIFFERENCES REGARDING THE EXACT
TIMING, LOCATION, AND AMPLITUDE OF AN UPPER LEVEL TROUGH THAT
WILL ATTEMPT TO PUSH INTO THE PACIFIC NORTHWEST FROM BRITISH
COLUMBIA. CONFIDENCE IS HIGHER ON FRIDAY, THEN DECREASES MORE AS
TIME GOES ON. THERE IS HIGH CONFIDENCE THAT TEMPERATURES WILL
TREND COOLER ON FRIDAY COMPARED TO EARLIER IN THE WEEK, BUT IT
IS NOT CLEAR HOW MUCH COOLER AS THE FULL RANGE OF OUTCOMES FOR
HIGH TEMPERATURES IS ANYWHERE FROM THE LOWER 60S TO UPPER 70S.
THE OUTCOME WILL BE HIGHLY DEPENDENT ON HOW DEEP THE TROUGH
BECOMES AND IF IT TRACKS INTO WASHINGTON AND OREGON OR FURTHER
TO THE EAST TOWARDS THE NORTHERN PLAINS, WHICH WILL ALSO
DETERMINE WHETHER OR NOT RAIN WILL RETURN TO THE AREA. IF RAIN
DOES RETURN, HIGHS IN THE 60S WOULD BE EXPECTED. IF RAIN DOES
NOT RETURN, HIGHS WOULD LIKELY TOP OUT SOMEWHERE IN THE 70S,
ASSUMING ENOUGH SUN BREAKS OCCUR. THE LATEST LREF RUN INDICATES
ABOUT 25-35% OF ENSEMBLE SOLUTIONS SUGGEST THE TROUGH WILL TAKE
A MORE EASTERN PUSH TOWARDS THE NORTHERN PLAN WITH 15-20% OF
THE SOLUTIONS SUGGESTING THE TROUGH WILL DEEPEN OFFSHORE OVER
THE EASTERN PACIFIC, BOTH OF WHICH ARE MORE DRIER SOLUTIONS. THE
OTHER 65-85% OF SOLUTIONS INDICATE THE TROUGH DEEPENING OVER
THE PACNW, THE WETTER SOLUTION. THIS IS A BIT FLIPPED FROM THE
12Z SEPT 6TH RUN, INDICATING HOW MUCH UNCERTAINTY STILL REMAINS
IN THE FORECAST. BY SUNDAY, THESE SOLUTIONS ARE EVEN MORE
DIVERGENT. HOWEVER, ONE THING I WILL NOTE IS THAT REMNANT
MOISTURE FROM HURRICANE MARIE IS NO LONGER EXPECTED TO BE
INJECTED INTO THIS TROUGH, MEANING THE OVERALL AMOUNT OF
PRECIPITATION EXPECTED THROUGH THE WEEKEND IS LOW. THE HIGH END
FORECAST OVER 48 HOURS ENDING 5 AM MONDAY IS AROUND 0.15-0.5
INCH ACROSS MOST OF THE AREA, LOCALLY UP TO 0.75 INCH OVER THE
CASCADES. THE CURRENT DETERMINISTIC FORECAST SUGGESTS LESS THAN
0.1 INCH, MAINLY OVER TERRAIN. -23/03
AVIATION...THROUGH 12Z TUESDAY
WITH THE LOW PRESSURE SYSTEM
NOW MOVING EAST OUT OF THE AIRSPACE, RAIN HAS ENDED AT ALL
TERMINALS. STILL, MVFR CIGS CONTINUE TO IMPACT MOST TERMINALS AS
OF 05Z MON AND MAY CONTINUE TO DO SO OVERNIGHT AS THERE IS HIGH
CONFIDENCE THAT WET SURFACE CONDITIONS FROM RECENT RAINS HAS
ALLOWED FOR THE FORMATION OF STRATUS. PROBABILISTIC GUIDANCE
SUGGESTS A 20-60% CHANCE OF MVFR CIGS BETWEEN 06-18Z MON AT INLAND
TERMINALS, WITH THE HIGHEST CHANCES BETWEEN 12-16Z MON. AS FOR
COASTAL TERMINALS, THERE IS A 60-80% CHANCE OF MVFR CIGS UNTIL
18-20Z MON, ALONG WITH A 20-40% CHANCE OF IFR AND 10-30% CHANCE OF
LIFR CONDITIONS AT KONP. OTHERWISE, EXPECT GENERALLY LIGHT AND
VARIABLE WINDS AT MOST TERMINALS THROUGH THE TAF PERIOD, WITH THE
EXCEPTION OF NORTHWEST WINDS AROUND 8 KT AT COASTAL TERMINALS
DURING THE AFTERNOON.
KPDX AND APPROACHES...CURRENT MVFR CIGS LIKELY TO CONTINUE
INTO THE MORNING HOURS AS GUIDANCE SUGGESTS CURRENT 20-30%
CHANCES OF MVFR CIGS TO INCREASE TO 50-60% BETWEEN 12-18Z MON.
EXPECT VFR CONDITIONS TO RETURN BY 18-20Z MON. LIGHT AND VARIABLE
WINDS EXPECTED THROUGH THE PERIOD, BECOMING NORTHWEST AFTER 20Z
MON. -12/03
MARINE
HIGH PRESSURE OFFSHORE WILL MAINTAIN PREDOMINATELY
NORTHERLY WINDS ACROSS THE COASTAL WATERS THROUGH THE WEEK. A WEAK
FRONT WILL BRING MORE VARIABLE WINDS EARLY MONDAY. A STRENGTHENING
PRESSURE GRADIENT ON TUESDAY WILL BRING STRONGER NORTHERLIES WITH
GUSTS UP TO 25 KT AS THERE IS AN 80% CHANCE OF WIND GUSTS
EXCEEDING 21 KT BY TUESDAY EVENING. AS A RESULT, SMALL CRAFT
ADVISORIES HAVE BEEN ISSUED FROM 8 AM TO 11 PM TUESDAY FOR ALL
THE WATERS. BREEZY WINDS CONTINUE THROUGH THURSDAY, BUT SHOULD
REMAIN 20 KT OR LESS. SEAS AT AROUND 3 TO 4 FT WITH A DOMINANT
NORTHWEST SWELL AT 8-9 SECONDS WILL GRADUALLY BUILD TO AROUND 6 FT
LATE TUESDAY. -03
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 2 PM TO 11 PM PDT TUESDAY FOR PZZ210-
251>253-271-272.
SMALL CRAFT ADVISORY FROM 8 AM TO 11 PM PDT TUESDAY FOR PZZ273.
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