075
FXUS66 KPQR 171150 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
450 AM PDT MON AUG 17 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 CHANCES FOR LIGHT SHOWERS ARRIVE FRIDAY
INTO NEXT WEEKEND.
DISCUSSION...NOW THROUGH SATURDAY
MINIMAL CHANGES TO THE
FORECAST. SEASONABLY DRY AND WARM CONDITIONS CONTINUE THROUGH
THE WEEK WITH MINIMAL WEATHER IMPACTS. THE LARGE-SCALE PATTERN
REMAINS 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 CONTINUES TO SHOW THE UPPER-LEVEL
TROUGH OVER THE NORTHEAST PACIFIC SHIFTING ONSHORE FRIDAY INTO
THE WEEKEND, RESULTING IN SLIGHTLY COOLER TEMPERATURES AND WINDS
COMING FROM THE SOUTH/SOUTHWEST. CHANCES FOR SHOWERS ALSO
INCREASE TO 10-25% ACROSS THE REGION DURING THIS TIME, WITH THE
HIGHEST CHANCES OVER THE COAST RANGE AND CASCADES. HOWEVER,
THERE IS STILL HIGH UNCERTAINTY IN THE TIMING AND POTENTIAL RAIN
AMOUNTS. A WEAK FRONT AT THE END OF THE WEEK WOULD HAVE A HARD
TIME COUNTERACTING THE DRY AIRMASS IN PLACE, MAKING ACCUMULATING
RAINFALL UNLIKELY AND KEEPING MOST PLACES DRY. -10/36
AVIATION...THROUGH 12Z TUESDAY
SATELLITE IMAGERY AND TERMINAL
OBSERVATIONS AS OF EARLY MONDAY MORNING DEPICTS A MARINE LAYER ALONG
THE COAST BRINGING IFR AND LOW-END MVFR (1-2 KFT) CONDITIONS TO
COASTAL TERMINALS, AND LOW-END MVFR STRATUS DEVELOPING ACROSS THE
PORTLAND METRO AREA. THERE IS A 20-30% CHANCE AT ANY GIVEN HOUR
BETWEEN 12-17Z MON FOR MVFR STRATUS DEVELOPING ACROSS THE CENTRAL
AND SOUTHERN WILLAMETTE VALLEY. HIGH CONFIDENCE FOR IFR/MVFR CIGS TO
PERSIST ALONG THE COAST AND PORTLAND METRO THROUGH 17Z MON. AFTER 17-
18Z MON, STRATUS WILL DISSIPATE AS DAYTIME HEATING PROGRESSES,
RETURNING VFR CONDITIONS WITH HIGH CLOUDS ACROSS ALL TERMINALS. VFR
CONDITIONS PREVAIL ACROSS THE VALLEY THROUGH THE REST OF THE TAF
PERIOD. MARINE STRATUS RE- BUILDS ALONG THE COAST AFTER 00-03Z TUE,
RETURNING IFR/MVFR CIGS (>80% CHANCE). NORTHERLY TO NORTHWESTERLY
WINDS TODAY 10-15 KT WITH GUSTS UP TO 20 KT ALONG THE COAST, AND 5-
10 KT ACROSS THE VALLEY. WINDS WILL BE STRONGEST IN THE AFTERNOON
AND EVENING, THEN WEAKEN OVERNIGHT.
KPDX AND APPROACHES...LOW-END MVFR (1-2 KFT) CIGS THROUGH 17Z MON.
AFTER 17Z MON, STRATUS DISSIPATES AND RETURNS VFR CONDITIONS WITH
HIGH CLOUDS THROUGH THE REST OF THE TAF PERIOD. NORTHWESTERLY WINDS
3-7 KT, STRONGEST IN THE AFTERNOON AND EVENING. -10
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
THE WEEKEND WILL SHIFT WINDS OUT OF THE SOUTH TO SOUTHWEST
ACROSS THE WATERS, BUT CHANCES FOR GUSTS EXCEEDING 21 KT REMAIN
LOW, ONLY 5-10%. SEAS OF 3-6 FT PERSIST THROUGH THE PERIOD.
INCREASING PERIODS OF 12-14 SEC ON TUESDAY-WEDNESDAY MAY RESULT
IN A MODERATE RISK FOR SNEAKER WAVES ALONG THE COAST. CAUTION
SHOULD BE USED WHEN IN OR NEAR THE WATER. -10/36
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
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