104
FXUS66 KPQR 170455
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
955 PM PDT SUN AUG 16 2026
UPDATED AVIATION DISCUSSION.
SYNOPSIS
SEASONABLY WARM AND DRY CONDITIONS EXPECTED THROUGH
MUCH OF THE WEEK WITH MORNING CLOUDS AND AFTERNOON CLEARING.
WINDS GENERALLY OUT OF THE WEST TO NORTHWEST, STRONGEST IN THE
AFTERNOON AND ALONG THE CENTRAL COLUMBIA RIVER GORGE AND UPPER
HOOD RIVER VALLEY. NEXT BEST CHANCES FOR LIGHT RAINFALL ARRIVE
FRIDAY INTO NEXT WEEKEND.
DISCUSSION...NOW THROUGH SATURDAY
SEASONABLY DRY AND WARM
CONDITIONS CONTINUE THROUGH THE WEEK WITH MINIMAL WEATHER
IMPACTS. THE LARGE-SCALE PATTERN REMAINS FAIRLY STAGNANT THROUGH
THE PERIOD, WITH BROAD AND RELATIVELY FLAT UPPER-LEVEL RIDGING
OVER THE MAJORITY OF CONUS AND A WEAK, POSITIVELY-TILTED UPPER-
LEVEL TROUGHING OVER THE NORTHEAST PACIFIC. THIS PATTERN WILL
SUPPORT CONTINUED ONSHORE FLOW, MAINTAINING NEAR-NORMAL DAILY
HIGH TEMPERATURES IN THE 80S WITHIN INLAND VALLEYS AND 60S ALONG
THE COAST, AND OVERNIGHT LOWS IN THE 50S ACROSS THE REGION.
MORNINGS WILL BE CHARACTERIZED BY CLOUDS, ESPECIALLY ALONG THE
COAST, WHICH WILL TEND TO CLEAR BY THE AFTERNOON. LIGHT WEST TO
NORTHWEST WINDS WILL, PEAKING EACH AFTERNOON. THE STRONGEST
WINDS ARE LIKELY TO BE ALONG THE CENTRAL COLUMBIA RIVER GORGE
AND HOOD RIVER VALLEY, BUT IMPACTS ARE NOT ANTICIPATED.
THE MAJORITY OF ENSEMBLE MEMBERS ARE IN AGREEMENT THAT UPPER-
LEVEL RIDGING OVER THE ROCKIES AND GREAT BASIN WILL BUILD LATE
IN THE WORKWEEK, WHICH WOULD FAVOR A BRIEF WARM-UP ON THURSDAY.
HOWEVER, ENSEMBLE GUIDANCE SHOWS THE UPPER-LEVEL TROUGH OVER
THE NORTHEAST PACIFIC SHIFTING ONSHORE FRIDAY INTO THE WEEKEND,
RESULTING IN SLIGHTLY COOLER TEMPERATURES AND WINDS COMING FROM
THE WEST TO SOUTHWEST. CHANCES FOR PRECIPITATION ALSO INCREASE
TO 10-30% ACROSS THE REGION DURING THIS TIME, HOWEVER, THERE IS
STILL HIGH UNCERTAINTY IN THE TIMING AND POTENTIAL RAIN AMOUNTS.
A WEAKER FRONT AT THE END OF THE WEEK WOULD HAVE A HARD TIME
COUNTERACTING THE DRY AIRMASS IN PLACE AND MAKE ACCUMULATING
RAINFALL UNLIKELY. -10/36
AVIATION...THROUGH 06Z TUESDAY
VFR FLYING CONDITIONS
CURRENTLY IN PLACE ACROSS THE AIRSPACE WILL GIVE WAY TO
INCREASING MVFR CHANCES AS LOW STRATUS DEVELOPS INITIALLY ALONG
THE COAST AND POTENTIALLY WITHIN INLAND VALLEYS TONIGHT. THERE
IS HIGH CONFIDENCE (70-90% CHANCE) IN CONDITIONS DETERIORATING
TO IFR AT COASTAL TERMINALS AS LOW STRATUS DEVELOPS BY 09-12Z
MON, WHILE CONFIDENCE IN VIS RESTRICTIONS IS LOWER. THERE
REMAINS HIGH UNCERTAINTY IF LOW CLOUD WILL BE ABLE TO PENETRATE
INLAND; THE HIGHEST CONFIDENCE (50-60% CHANCE) FOR MVFR CIGS IS
ALONG THE LOWER COLUMBIA RIVER INTO PORTLAND-AREA TERMINALS
EXCLUDING KHIO, WHILE CHANCES ARE LOWER (30-50%) AT WILLAMETTE
VALLEY TERMINALS. CHANCES FOR MVFR CIGS RISE ABOVE 50% IN THE
HOURS AROUND SUNRISE, 11-13Z MON, AT KPDX/KTTD, AND PERSIST
THROUGH MUCH OF THE MORNING.
BY 16-18Z MON, DIURNAL MIXING WILL FAVOR CLEARING SKIES AND
LIFTING CLOUD BASES, WITH PREVAILING VFR AGAIN VERY LIKELY AT
INLAND TERMINALS. ALONG THE COAST, LOW CLOUDS WILL BE SLOW TO
ERODE, WITH VFR CONDITIONS MOST LIKELY TO BE LIMITED TO THE
MID-AFTERNOON, IF AT ALL; THERE ARE MODEST (25-35%) CHANCES
THAT MVFR CIGS MAY PERSIST THROUGH THE AFTERNOON.
LIGHT NORTH TO NORTHWEST WINDS TONIGHT WILL BUILD TO 5-10 KT AT
INLAND TERMINALS AND TO 10-15 KT WITH GUSTS NEAR 20 KT ALONG
THE COAST BY 17-19Z MON. WINDS EASE AGAIN LATE IN THE PERIOD.
KPDX AND APPROACHES...HIGH CONFIDENCE IN CONTINUED VFR
CONDITIONS THROUGH AT LEAST 08-10Z MON BENEATH SCT-BKN HIGH
CLOUDS. ONLY MODERATE CONFIDENCE IN THE POTENTIAL FOR MVFR CIGS
WITH CHANCES PEAKING AT 50-60% FROM 13-17Z MON. HIGH CONFIDENCE
IN VFR CIGS AS DIURNAL MIXING ERODES LOW CLOUD COVERAGE BY
18-19Z MON. NORTHWEST WINDS EASE BELOW 5 KT TONIGHT, THEN BUILD
TO 5-10 KT BY MIDDAY MONDAY. -36
MARINE
A LARGELY STAGNANT PATTERN CONTINUES THROUGH MUCH OF
THE WEEK WITH HIGH PRESSURE OFFSHORE SUPPORTING NORTHERLY TO
NORTHWESTERLY WINDS OF 8-15 KT AND AFTERNOON GUSTS UP TO 20 KT.
WEAK LOW PRESSURE MOVING OVER THE NORTHEAST PACIFIC FRIDAY INTO
NEXT WEEKEND WILL SHIFT WINDS OUT OF THE WEST TO SOUTHWEST
ACROSS THE WATERS, BUT CHANCES FOR GUSTS EXCEEDING 21 KT REMAIN
LOW, ONLY 5-10%. BENIGN SEAS OF 3-6 FT PERSIST THROUGH THE
PERIOD. -10/36
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
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