977
FXUS66 KPQR 151745 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE PORTLAND OR
1045 AM PDT TUE SEP 15 2026
UPDATED AVIATION DISCUSSION
SYNOPSIS
A WEAK TROUGH WILL BRING INCREASING CLOUDS AND A
FEW LIGHT SHOWERS TO THE HIGHER TERRAIN TODAY, WITH SEASONABLY
COOL TEMPERATURES CONTINUING. WARMER AND DRIER CONDITIONS RETURN
WEDNESDAY AND THURSDAY AS EASTERLY FLOW DEVELOPS, FOLLOWED BY
RENEWED UNCERTAINTY IN TEMPERATURES FRIDAY THROUGH THE WEEKEND.
DISCUSSION...NOW THROUGH SUNDAY
THE WEATHER PATTERN WILL
UNDERGO A FAIRLY NOTICEABLE TRANSITION OVER THE NEXT COUPLE OF
DAYS. FOR TODAY, A WEAK UPPER-LEVEL TROUGH WILL MOVE ACROSS THE
PACIFIC NORTHWEST WHILE MOISTURE REMAINS LIMITED. INCREASING MID
AND HIGH LEVEL CLOUDS OVERNIGHT WILL LIKELY BE FOLLOWED BY
AREAS OF LOW CLOUDS AND PATCHY FOG IN THE INTERIOR VALLEYS THIS
MORNING. SOME CLOUD COVER SHOULD PERSIST INTO THE AFTERNOON,
KEEPING TEMPERATURES IN THE UPPER 60S TO LOW 70S ACROSS THE
INTERIOR AND IN THE 60S ALONG THE COAST. DESPITE THE PASSAGE OF
THE TROUGH, MEASURABLE PRECIPITATION IS UNLIKELY FOR MOST
LOCATIONS. THE BEST CHANCES, AROUND 30-50%, WILL BE CONFINED TO
THE NORTH OREGON COAST RANGE, WILLAPA HILLS AND CASCADE CREST,
WITH PROBABILITIES AROUND 5-15% ELSEWHERE.
THE TROUGH WILL SHIFT SOUTHWARD TONIGHT INTO WEDNESDAY AS
RIDGING STRENGTHENS OFFSHORE AND BEGINS TO BUILD INTO THE
PACIFIC NORTHWEST. THIS WILL MARK THE START OF A MUCH WARMER
PATTERN, WITH INTERIOR HIGHS CLIMBING INTO THE UPPER 70S TO LOW
80S WEDNESDAY. A DEVELOPING THERMAL TROUGH ALONG THE COAST AND
CASCADE FOOTHILLS WILL ALSO TURN THE LOW-LEVEL FLOW OFFSHORE,
RESULTING IN INCREASING EASTERLY WINDS THROUGH THE COLUMBIA
RIVER GORGE AND OTHER EAST-WEST ORIENTED TERRAIN GAPS. PRESSURE
GRADIENTS BETWEEN KTTD AND KDLS ARE EXPECTED TO FALL INTO THE -1
TO -3 MB RANGE, SUPPORTING GUSTS AROUND 20-25 MPH IN THE GORGE
AND LOCALLY BREEZIER CONDITIONS OVER EXPOSED TERRAIN AND
RIDGETOPS. THE CENTRAL AND SOUTHERN WILLAMETTE VALLEY SHOULD
ALSO BECOME BREEZY AS WINDS TURN MORE NORTHERLY. THERE IS A
30-50% CHANCE OF GUSTS EXCEEDING 30 MPH IN THE GORGE WEDNESDAY,
WITH PROBABILITIES AROUND 5-15% ACROSS THE CENTRAL AND SOUTHERN
VALLEY. DESPITE THE WARMER TEMPERATURES AND INCREASING WINDS,
AFTERNOON HUMIDITY SHOULD REMAIN ABOVE 30%, KEEPING FIRE-WEATHER
CONCERNS MINIMAL.
THURSDAY CURRENTLY APPEARS TO BE THE WARMEST DAY OF THE WEEK.
WEAK OFFSHORE FLOW WILL CONTINUE THROUGH THE MORNING, WITH
MODERATE TO HIGH CONFIDENCE FOR INTERIOR TEMPERATURES REACHING
THE LOW 80S. THE THERMAL TROUGH SHOULD THEN WEAKEN THURSDAY
AFTERNOON, ALLOWING ONSHORE FLOW TO RETURN AND LIMITING FURTHER
WARMING. MEANWHILE, THE UPPER-LEVEL TROUGH WILL SHIFT EAST
TOWARD THE GREAT BASIN. SOME WRAP-AROUND MOISTURE COULD PRODUCE
A 5-10% CHANCE OF THUNDERSTORMS ALONG THE CREST OF THE LANE
COUNTY CASCADES THURSDAY, WHILE THE REMAINDER OF THE FORECAST
AREA REMAINS DRY AND OUTSIDE THE THUNDERSTORM THREAT. SPC HAS
INCLUDED A PORTION OF THE LANE COUNTY CASCADES IN A GENERAL
THUNDERSTORM RISK, SO THIS POTENTIAL WILL NEED TO BE MONITORED
AS THURSDAY APPROACHES.
THE FORECAST BECOMES MORE UNCERTAIN FRIDAY THROUGH THE WEEKEND
AS ENSEMBLE GUIDANCE DIVERGES ON HOW QUICKLY THE UPPER-LEVEL
PATTERN EVOLVES. ROUGHLY HALF OF THE GUIDANCE MAINTAINS WEAK
TROUGHING OVER THE GREAT BASIN, WHICH WOULD KEEP TEMPERATURES
CLOSER TO THE LOW 70S, WHILE THE OTHER HALF FAVORS STRONGER
RIDGING OVER THE PACIFIC NORTHWEST AND WARMER TEMPERATURES
POTENTIALLY REACHING THE MID 80S. THUS, THERE IS STILL A FAIRLY
BROAD RANGE IN POSSIBLE TEMPERATURES LATE IN THE WEEK, BUT THE
OVERALL SIGNAL CONTINUES TO FAVOR DRY WEATHER WITH ABOVE-
SEASONAL-AVERAGE TEMPERATURES. ~12
AVIATION...THROUGH 18Z WEDNESDAY
WESTERLY FLOW ALOFT TURNS
NORTH-NORTHEASTERLY TONIGHT AS AN UPPER LEVEL TROUGH DROPS
SOUTHWARD OVER THE PACIFIC NORTHWEST. PREDOMINATELY VFR CONDITIONS
ARE EXPECTED TO CONTINUE AS MID TO HIGH LEVEL CLOUDS DRIFT ACROSS
THE AIRSPACE. LOWER VFR STRATUS IS LIKELY ALONG THE NORTH OREGON
COAST THROUGH THIS AFTERNOON WITH SPOTTY RAIN SHOWERS POSSIBLE.
CHANCES FOR MVFR CIGS AT COASTAL TERMINALS REMAIN AROUND 20%
THROUGH 23Z TODAY. OTHERWISE, EXPECT LIGHT WINDS TO BECOME NORTH
TO NORTHWEST AROUND 4-8 KT THROUGH EARLY THIS EVENING.
KPDX AND APPROACHES...VFR CONDITIONS EXPECTED THROUGH THE TAF
PERIOD, WITH MID TO HIGH LEVEL CLOUDS THROUGH THIS EVENING.
NORTHWEST WINDS PERSIST AT AROUND 3-6 KT. /DH
MARINE
NORTH TO NORTHWEST WINDS CONTINUE TODAY AS HIGH
PRESSURE BUILDS OFFSHORE. 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. AS A RESULT, SMALL CRAFT ADVISORIES HAVE
BEEN ISSUED FOR THE WATERS SOUTH OF CAPE FALCON FROM 2 TO 11 PM
WEDNESDAY. SMALL CRAFT WINDS COULD HOLD ON UNTIL 2 AM THURSDAY BUT
CONFIDENCE REMAINS LOW AT THIS TIME. 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 NORTHERLY WINDS STRENGTHEN. 12/23
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 2 PM TO 11 PM PDT WEDNESDAY FOR PZZ252-
253-272-273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page