346
FXUS66 KPQR 281816 AAB
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1115 AM PDT TUE JUL 28 2026
UPDATED AVIATION DISCUSSION.
SYNOPSIS
PERSISTENT ONSHORE FLOW WILL BRING NEAR-AVERAGE
TEMPERATURES WITH VARYING DEGREES OF MORNING CLOUDS AND
AFTERNOON SUNSHINE FOR MUCH OF THE NEXT WEEK. A SERIES OF WEAK
FRONTS WILL BRING NOTABLE CHANCES FOR LIGHT RAIN AND DRIZZLE TO
PORTIONS OF THE WASHINGTON AND NORTH OREGON COASTS TODAY AND
THIS WEEKEND, WHILE FRIDAY IS LIKELY TO BE THE WARMEST DAY.
DISCUSSION...NOW THROUGH MONDAY
THE LARGE-SCALE PATTERN WILL
REMAIN FAIRLY STEADY THROUGH THE NEXT WEEK WITH THE REGION
WEDGED BETWEEN UPPER-LEVEL TROUGHING OVER THE GULF OF ALASKA AND
UPPER-LEVEL RIDGING OVER THE ROCKIES AND CENTRAL PLAINS. IN
GENERAL, THE WEATHER LOCALLY WILL BE TYPICAL FOR THE MID-SUMMER:
MORNING CLOUDS FOLLOWED BY INCREASING AFTERNOON SUNSHINE,
SEASONABLE TEMPERATURES, AND LARGELY DRY CONDITIONS, BUT WITH
SOME VARIATIONS AS THE RELATIVE STRENGTHS OF THESE TWO DOMINANT
FEATURES CHANGE.
TODAY, AN UPPER SHORTWAVE PASSING TO THE NORTH WILL TILT THE
SCALES IN FAVOR OF UPPER TROUGHING, SENDING FRONT TOWARD THE
COAST RESULTING IN SLIGHTLY BELOW NORMAL TEMPERATURES ACROSS THE
REGION, NAMELY AFTERNOON HIGHS IN THE LOW TO MID 60S AT THE
COAST AND UPPER 70S TO LOW 80S WITHIN INLAND VALLEYS, AS WELL AS
CHANCES FOR LIGHT RAIN OR DRIZZLE ALONG THE NORTHERN OREGON AND
SOUTHERN WASHINGTON COASTS AND WITHIN COASTAL TERRAIN. CHANCES
FOR ACCUMULATING RAINFALL (0.01 INCHES OR MORE) ARE LESS THAN
10% IN LINCOLN AND LANE COUNTIES, 20-40% IN TILLAMOOK AND
CLATSOP COUNTIES, AND 50-80% IN PACIFIC COUNTY. INLAND, CHANCES
ARE LOWER, ONLY 5-25% FROM THE PORTLAND METRO NORTH INTO THE
LOWER COLUMBIA AND COWLITZ VALLEYS.
WEDNESDAY THROUGH FRIDAY, THE UPPER-LEVEL RIDGE WILL STRENGTHEN
AND RETROGRADE WESTWARD INTO THE GREAT BASIN, INCREASING
HEIGHTS ALOFT LOCALLY AND TIPPING THE BALANCE TOWARD WARMER AND
DRIER WEATHER. CONTINUED ONSHORE FLOW WILL LIMIT THE LIKELIHOOD
OF HAZARDOUS HEAT, BUT EXCEPT ABOVE-NORMAL HIGH TEMPERATURES
MOST LIKELY IN THE UPPER 60S TO LOW 70S ALONG THE COAST AND IN
THE MID TO UPPER 80S WITHIN INLAND VALLEYS BY FRIDAY. THESE
TEMPERATURES RESULT IN ONLY MINOR HEATRISK ACROSS THE REGION,
WITH THE CHANCES FOR MODERATE HEATRISK OF AROUND 5% ALONG MOST
OF THE I-5 CORRIDOR EXCEPT 15-45% IN THE PORTLAND/VANCOUVER
METRO, HIGHEST IN THE TUALATIN VALLEY.
BY THE WEEKEND, THERE IS HIGHER UNCERTAINTY IN THE EVOLUTION OF
THE UPPER-LEVEL PATTERN, BUT MANY ENSEMBLE MEMBERS DEPICT MORE
PRONOUNCED TROUGHING RETURNING TO THE PACIFIC NORTHWEST,
FAVORING COOLER TEMPERATURES AND FURTHER CHANCES FOR RAINFALL.
AT THIS TIME, RAIN CHANCES PEAK ON SATURDAY ALONG THE COAST AND
ESPECIALLY FROM LINCOLN CITY NORTHWARD. -36
AVIATION...THROUGH 18Z WEDNESDAY
AT 18Z TUESDAY, SATELLITE AND
SURFACE WEATHER OBSERVATIONS DEPICTED MOSTLY CLEAR SKIES OVER THE
OREGON CASCADES AND WILLAMETTE VALLEY. A NARROW BAND OF CLOUDS
WITH VFR CEILINGS AROUND 7000 FT REMAINED IN PLACE OVER KPDX AMD
KTTD, HOWEVER THIS CLOUD DECK IS EXPECTED TO SCATTER OUT BY THE
EARLY AFTERNOON. MEANWHILE, A DECAYING COLD FRONT WAS BEGINNING TO
PUSH INLAND ALONG THE SOUTH WASHINGTON AND NORTH OREGON COAST.
THIS FRONT WILL BRING A BRIEF PERIOD OF LIGHT RAIN TO KAST BETWEEN
18-19Z TUESDAY. THE REMAINING TAF SITES SHOULD STAY DRY. MVFR
CEILINGS AT KONP ARE ALREADY BEGINNING TO SCATTER OUT, AND MVFR
CEILINGS ARE EXPECTED TO SCATTER OUT AT KAST BY 19-20Z TUESDAY.
THE MAIN UNCERTAINTY WITH THE AVIATION FORECAST IS EXACT CEILING
HEIGHTS LATE TONIGHT INTO TOMORROW MORNING, AS WELL AS WHETHER OR
NOT CLOUD COVER WILL BE PREDOMINATELY SCATTERED OR BROKEN. THE
LATEST GUIDANCE CURRENTLY SUGGESTS A BROKEN CLOUD DECK WILL
ATTEMPT DEVELOPING OVER THE NORTH OREGON CASCADES AND PORTIONS OF
THE WILLAMETTE VALLEY AND PORTLAND METRO BETWEEN 06-12Z WEDNESDAY.
HOWEVER, PROBABILITIES CURRENTLY FAVOR LOW-END VFR CEILINGS WITH
THIS POTENTIAL STRATUS DECK. PROBABILITIES FOR MVFR CEILINGS
BELOW 3000 FT PEAK BETWEEN 10-16Z WEDNESDAY BETWEEN 15-35% AT ALL
TAF SITES, EXCEPT 45-55% AT KAST.
KPDX AND APPROACHES...SCATTERED CLOUDS WITH CEILINGS ABOVE 7000 FT
ARE EXPECTED TODAY, RESULTING IN VFR CONDITIONS. VFR CONDITIONS
WILL MOST LIKELY REMAIN IN PLACE THROUGH 18Z WEDNESDAY, HOWEVER
THERE IS A 15% CHANCE FOR MVFR CEILINGS BELOW 3000 FT BETWEEN
10-16Z WEDNESDAY. LIGHT AND VARIABLE WINDS AROUND 5 KT ARE
EXPECTED TO BECOME NORTHWESTERLY LATER THIS AFTERNOON, WITH GUSTS
UP TO APPROXIMATELY 15 KT BY THE LATE AFTERNOON WITH AN INCOMING
SEA BREEZE. -23
MARINE
SEAS OF 4-5 FT PER BUOY OBSERVATIONS ARE EXPECTED TO
CONTINUE WITH A DOMINANT WEST TO NORTHWEST SWELL AT 8-9 SECONDS
AND A SECONDARY LONG-PERIOD SOUTH-SOUTHWESTERLY SWELL PERSISTING
THROUGH MUCH OF THE WEEK. LIGHT SOUTHERLY WINDS EARLY THIS
MORNING WILL BUILD AND VEER OUT OF THE NORTH TO NORTHWEST BY
THIS EVENING BEHIND A WEAK FRONTAL BOUNDARY. MAXIMUM GUSTS WILL
MOST LIKELY REMAIN IN THE 15-20 KT RANGE, HOWEVER INTERMITTENT
OR ISOLATED GUSTS TO 25 KT MAY OCCUR DURING THE FRONTAL PASSAGE,
MOST LIKELY TO THE NORTH OF CAPE FALCON. MORE TYPICAL SUMMERTIME
NORTHERLIES WILL THEN CONTINUE THROUGH THE REMAINDER OF THE
WORKWEEK.
ANOTHER WEAK FRONT LOOKS TO TRAVERSE THE WATERS EARLY THIS
WEEKEND, AFTER WHICH NORTHWESTERLY FLOW WILL STRENGTHEN AND
VEER OUT OF NORTH INTO EARLY NEXT WEEK AS HIGH PRESSURE BUILDS
OFFSHORE. CONFIDENCE IN WIND GUSTS OF AT LEAST 20-25 KT IS
MODERATE TO HIGH ON SUNDAY, INCREASING FROM AROUND 60% WEST OF
THE MOUTH OF THE COLUMBIA TO GREATER THAN 90% OFFSHORE OF
FLORENCE. THOSE CHANCES ARE EVEN HIGHER ON MONDAY, SOME 90-95%
OR HIGHER ACROSS THE COASTAL WATERS. THE CHANCES FOR GALE-FORCE
GUSTS ON MONDAY ARE LOW BUT NOT NEGLIGIBLE, GENERALLY 10-20%
SOUTH OF CAPE FOULWEATHER AS WELL AS WITHIN 10 NM OF THE COAST
FROM CAPE FALCON TO CAPE FOULWEATHER. -36
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
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