906
FXUS66 KPQR 142350 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE PORTLAND OR
450 PM PDT MON SEP 14 2026
UPDATED AVIATION DISCUSSION.
SYNOPSIS
DRY AND SEASONABLY COOL TODAY AND TUESDAY, WITH
INCREASING CLOUDS OVERNIGHT AS A WEAK UPPER-LEVEL TROUGH MOVES
IN. DRIER AND WARMER CONDITIONS ARRIVE WEDNESDAY TO THURSDAY
WITH INCREASING EASTERLY WINDS THROUGH THE COLUMBIA RIVER
GORGE AND CASCADES. ONSHORE FLOW RETURNS THURSDAY AFTERNOON. DRY
AND WARM CONDITIONS CONTINUE FRIDAY THROUGH THE WEEKEND, BUT
THERE REMAINS UNCERTAINTY WITH HOW WARM WE WILL GET.
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
SATELLITE IMAGERY
AND SURFACE OBSERVATIONS AS OF EARLY MONDAY AFTERNOON DEPICTS
SCATTERED TO BROKEN CLOUD COVER ACROSS NORTHWEST OREGON AND
SOUTHWEST WASHINGTON AS WEAK HIGH PRESSURE RE-BUILDS OVER THE
AREA FOLLOWING THE LOW PRESSURE THIS PAST WEEKEND. CLOUDS WERE
BRIEFLY BREAKING OUT LATE THIS MORNING, BUT DAYTIME HEATING HAS
RESULTED IN SOME POPCORN CUMULUS CLOUDS ACROSS THE AREA WHICH
MAY LINGER INTO THE AFTERNOON. AS A RESULT, EXPECT SEASONABLY
COOL TEMPERATURES TODAY WITH AFTERNOON HIGHS PEAKING IN THE
UPPER 60S TO LOW 70S ACROSS INTERIOR VALLEYS, AND LOW TO MID 60S
ALONG THE COAST.
TONIGHT, ANOTHER UPPER-LEVEL SHORTWAVE TROUGH WILL APPROACH THE
PACIFIC NORTHWEST, BRINGING INCREASING MID TO HIGH LEVEL CLOUDS.
SOME OF THESE CLOUDS MAY BE THIN ENOUGH TO KEEP SKIES CLEAR
ENOUGH TO SUPPORT PATCHY FOG DEVELOPMENT ACROSS INTERIOR
VALLEYS. CLOUDS AND ANY PATCHY FOG WILL LINGER THROUGHOUT THE
MORNING AND THEN SLOWLY BREAK OUT TUESDAY AFTERNOON/EVENING.
EXPECT HIGH TEMPERATURES TUESDAY AFTERNOON TO PEAK IN THE UPPER
60S TO LOW 70S ACROSS INTERIOR VALLEYS, SIMILAR TO TODAY DUE TO
THE MORNING CLOUD COVER. DESPITE THE TROUGH DROPPING DOWN ON
TUESDAY, LIMITED MOISTURE WITH THIS WEAK SYSTEM WILL RESULT IN
MOSTLY DRY CONDITIONS. CHANCES FOR MEASURABLE PRECIPITATION ON
TUESDAY (>0.01") ARE ONLY 20-30% ACROSS THE NORTH OREGON COAST
RANGE, WILLAPA HILLS, AND THE CREST OF THE CASCADES, AND <5%
EVERYWHERE ELSE.
ON WEDNESDAY, THE AFOREMENTIONED UPPER TROUGH WILL CONTINUE TO
DROP INTO SOUTHERN OREGON AND NORTHERN CALIFORNIA WHILE AN
UPPER-LEVEL RIDGE AMPLIFIES OFFSHORE AND ITS RIDGE AXIS EXTENDS
INTO WESTERN WASHINGTON. AT THE SURFACE, GUIDANCE IS IN
AGREEMENT THAT THERMAL TROUGHING WILL DEVELOP ALONG THE COAST
AND CASCADE FOOTHILLS, RESULTING IN LIGHT EASTERLY WINDS THROUGH
THE COLUMBIA RIVER GORGE, AND COAST RANGE/CASCADE GAPS. ENSEMBLE
GUIDANCE SHOWS PRESSURE GRADIENTS ANYWHERE BETWEEN -1 TO -3 MB
BETWEEN KTTD AND KDLS, WHICH WOULD TRANSLATE TO WIND GUSTS
PEAKING UP TO 20-25 MPH THROUGH THE GORGE AND OTHER EAST/WEST
ALIGNED TERRAIN GAPS. ACROSS THE WILLAMETTE VALLEY, WINDS WILL
TURN MORE NORTHERLY AND BE BREEZIEST ACROSS THE CENTRAL AND
SOUTHERN VALLEY. CHANCES FOR MAXIMUM WIND GUSTS EXCEEDING 30 MPH
ON WEDNESDAY ARE AROUND 30-50% ALONG THE GORGE, AND 15-20% FOR
THE CENTRAL/SOUTHERN VALLEY. EXPECT THE STRONGEST GUSTS OVER
HIGHER TERRAIN AND EXPOSED RIDGETOPS. GIVEN THAT EASTERLY WINDS
ARE NOT LOOKING TOO STRONG AND AFTERNOON HUMIDITIES ARE WELL
ABOVE 25%, MINIMAL FIRE WEATHER CONCERNS ARE EXPECTED. THE
EASTERLY OFFSHORE WINDS WILL ALSO HELP WITH INCREASING
TEMPERATURES, WITH HIGHS REBOUNDING INTO THE UPPER 70S TO LOW
80S ACROSS INTERIOR VALLEYS WEDNESDAY AFTERNOON. -10
LONG TERM...THURSDAY THROUGH SUNDAY
THURSDAY IS SHAPING UP TO
BE THE WARMEST DAY OF THE WEEK, WITH HIGH CONFIDENCE (70-90%)
FOR HIGH TEMPERATURES PEAKING IN THE LOW 80S ACROSS INTERIOR
VALLEYS AS WEAK OFFSHORE FLOW CONTINUES THROUGH THE MORNING. BY
THURSDAY AFTERNOON, WINDS SHOULD BEGIN TO SHIFT BACK INTO AN
ONSHORE DIRECTION (WEST TO EAST) AS THE THERMAL TROUGH BREAKS
DOWN. THE WEAK UPPER-LEVEL TROUGH WILL ALSO BEGIN TO GRADUALLY
SHIFT EASTWARD INTO THE GREAT BASIN, AND WRAP-AROUND MOISTURE
WILL SUPPORT A 10-15% CHANCE FOR THUNDERSTORMS ALONG THE CREST
OF THE LANE COUNTY CASCADES. EVERYWHERE ELSE SHOULD REMAIN DRY
AND OUT OF ANY THUNDERSTORM THREAT.
FRIDAY TO THE WEEKEND, THE MAJORITY OF ENSEMBLE MEMBERS CONTINUE
TO FAVOR WARM AND DRY CONDITIONS FOR THE REGION, HOWEVER, THERE
IS UNCERTAINTY WITH HOW WARM WE'LL GET. ABOUT 45% OF THE
ENSEMBLE MEMBERS CONTINUE TO PLACE WEAK UPPER-LEVEL TROUGHING
OVER THE GREAT BASIN, MAINTAINING MORE MILD TEMPERATURES. THE
OTHER 55% OF ENSEMBLE MEMBERS SHOW UPPER-LEVEL RIDGING BUILDING
OVER THE PACIFIC NORTHWEST, WHICH WOULD FAVOR WARMER
TEMPERATURES. AS A RESULT, THERE'S A PRETTY WIDE RANGE IN HIGH
TEMPERATURES FRIDAY TO THE WEEKEND, WITH THE COOLEST SCENARIO
BEING IN THE LOW 70S, AND THE WARMEST SCENARIO BEING IN THE
UPPER 80S AND CLOSE TO 90 DEGREES. -10
AVIATION...THROUGH 00Z TUESDAY
NORTHWEST FLOW ALOFT BECOMES
MORE WESTERLY TONIGHT AS AN UPPER LEVEL TROUGH DROPS SOUTH OUT OF
WESTERN CANADA. AS OF 2330Z MONDAY, SKIES WERE MOSTLY CLEAR FROM
KSLE TO KEUG AND ALONG THE COAST FROM KONP SOUTHWARD. NORTH OF A
LINE EXTENDING FROM KONP TO KSLE, CLOUDS WERE SCATTERED TO BROKEN
WITH CEILINGS AROUND 5000-6000 FT. EXPECT THIS TREND TO CONTINUE
TONIGHT INTO TOMORROW MORNING WHILE A SECONDARY CLOUD DECK AROUND
10 KFT MOVES IN FROM THE NORTH. THAT SAID, THERE ARE A FEW
POTENTIAL EXCEPTIONS. PROBABILITIES FOR MVFR CEILINGS AROUND
2500-3000 FT HAVE INCREASED TO 60-80% AT KAST AFTER 06Z TUESDAY.
PROBABILITIES PEAK NEAR 50% AT KTTD AND KONP. THEREFORE, HAVE
DECIDED TO INCLUDE A MENTION OF MVFR CEILINGS AT KAST, BUT HAVE
NOT INCLUDED MVFR CEILINGS AT KTTD AND KONP AS CONFIDENCE IS LOWER
FOR THESE TWO TAF SITES. IN ADDITION, CONFIDENCE IS NOW HIGH
ENOUGH TO INCLUDE A MENTION OF FOG AT KEUG BEGINNING AT 12Z
TUESDAY GIVEN THE LIGHT WINDS AND MOSTLY CLEAR SKIES THAT WILL BE
IN PLACE. HOWEVER, FOG WILL MOST LIKELY ONLY LAST 2-3 HOURS,
SIMILAR TO WHAT WAS OBSERVED MONDAY MORNING.
KPDX AND APPROACHES...VFR EXPECTED THROUGH THE TAF PERIOD, WITH
CLOUDS GRADUALLY SCATTERING OUT THIS EVENING. HIGH LEVEL CLOUDS
DEVELOP TONIGHT INTO TOMORROW MORNING WITH CEILINGS AROUND 10 KFT.
LIGHT NORTHWEST WINDS AROUND 3-6 KT ARE EXPECTED THROUGHOUT THE
TAF PERIOD. -23
MARINE
LIGHT WINDS OVER THE WATERS BECOME NORTH TO NORTHWEST BY
THIS EVENING AS HIGH PRESSURE BUILDS OFFSHORE. WINDS GENERALLY
INCREASE UP TO 10-15 KT TONIGHT THROUGH TUESDAY. A STRENGTHENING
THERMAL TROUGH ALONG THE COAST IS EXPECTED TO INCREASE PRESSURE
GRADIENTS ACROSS THE COASTAL WATERS ON WEDNESDAY, INCREASING
NORTHERLIES TO 15-20 KT WITH AT LEAST AN 80-90% CHANCE FOR WIND
GUSTS EXCEEDING 21 KT SOUTH OF CAPE FALCON. WINDS ARE LIKELY TO
EASE LATER IN THE WEEK AS LOW PRESSURE DRIFTS OFFSHORE. A
PERSISTENT NORTHWEST SWELL AROUND 4 TO 5 FT AT 7 TO 8 SECONDS IS
EXPECTED TO CONTINUE THROUGH TUESDAY. SEAS THEN BUILD TO AROUND 6
FT ON WEDNESDAY AS WIND CHOP INCREASES WITH STRENGTHENING
NORTHERLIES. /DH
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
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