733
FXUS66 KPQR 280529
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1029 PM PDT MON JUL 27 2026
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 TUESDAY AND
NEXT WEEKEND, WHILE FRIDAY IS LIKELY TO BE THE WARMEST DAY.
DISCUSSION...MONDAY AFTERNOON THROUGH SUNDAY
THERE HAS BEEN
VERY LITTLE CHANGE TO THE FORECAST TODAY. THE LARGE- SCALE
PATTERN REMAINS 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 STRENGTHS OF THESE TWO DOMINANT
FEATURES CHANGE RELATIVE TO ONE ANOTHER.
UPPER RIDGING WINS OUT TODAY AS HEIGHTS ALOFT HAVE RISEN
MARGINALLY. MORNING STRATUS HAS DISSIPATED WITH MOSTLY CLEAR
SKIES AND SEASONABLY WARM HIGH TEMPERATURES EXPECTED IN THE 60S
TO LOW 70S ON THE COAST AND MID 80S WITHIN THE WILLAMETTE
VALLEY. ON TUESDAY, AN UPPER SHORTWAVE PASSING TO THE NORTH WILL
TILT THE SCALES IN FAVOR OF UPPER TROUGHING, SENDING A WEAK
FRONT TOWARD THE COAST RESULTING IN COOLER TEMPERATURES ACROSS
THE REGION AND CHANCES FOR LIGHT RAIN OR DRIZZLE ALONG THE COAST
AND COAST RANGE. TEMPERATURES ARE ALSO FORECAST TO BE A FEW
DEGREES COOLER THAN TODAY AS CLOUD COVER MAY PERSIST ACROSS THE
REGION THROUGH THE AFTERNOON HOURS.
WEDNESDAY INTO THURSDAY, THE UPPER-LEVEL RIDGE STRENGTHENS
SLIGHTLY, INCREASING HEIGHTS ALOFT LOCALLY AND AGAIN TIPPING
THE BALANCE TOWARD DRY WEATHER, THOUGH SMALLER SHORTWAVES ALONG
THE FLOW WILL KEEP TEMPERATURES IN THE LOW 80S FOR THE INTERIOR
LOWLANDS. ON FRIDAY, UPPER HIGH PRESSURE SPREADS FARTHER WEST
INTO THE REGION, INCREASING HEIGHTS ALOFT LOCALLY AND ALLOWING
FOR WARMER TEMPERATURES. DAYTIME TEMPERATURES ARE FORECAST TO
PEAK IN THE UPPER 60S TO LOW 70S ALONG THE COAST AND UPPER 80S
FOR THE INTERIOR LOWLANDS. DESPITE THIS TREND, ONSHORE FLOW
WILL CONTINUE, LIMITING THE RISK FOR HAZARDOUS HEAT. MINOR
HEATRISK IS FAVORED FOR THE ENTIRE REGION ON FRIDAY, WITH 20-40%
CHANCES FOR MODERATE HEATRISK IN URBAN AND SUBURBAN AREAS FROM
SALEM NORTH TO VANCOUVER, WA.
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.
THE DETAILS OF TIMING AND POTENTIAL RAINFALL AMOUNTS REMAIN
FUZZY AT THIS LEAD TIME, BUT THOSE NEAR THE COAST OR WITHIN
COASTAL TERRAIN WILL BE THE MOST LIKELY BENEFICIARIES OF ANY
RAINFALL, WITH CHANCES INCREASING TO THE NORTH. -36/03
AVIATION
STRATUS IS BEGINNING TO THICKEN ALONG THE COAST
LATE THIS EVENING VIA SATELLITE AND SURFACE OBSERVATIONS WITH
MVFR CIGS IN PLACE AT KONP AND KAST. THERE REMAINS SOME
UNCERTAINTY REGARDING EXACTLY HOW LOW CEILINGS WILL GET AT KONP,
ALTHOUGH LOW-END MVFR TO IFR CEILINGS ARE THE MOST LIKELY
OUTCOME BY 12-13Z. STILL, THERE IS AROUND A 50-60% CHANCE FOR
IFR CEILINGS BELOW 1000 FT IN THE 12-17Z TIME PERIOD. INLAND TAF
SITES WILL MOST LIKELY REMAIN VFR THE REST OF TONIGHT INTO THE
MORNING, HOWEVER THERE IS A 20-35% CHANCE FOR A PERIOD OF MVFR
CEILINGS BETWEEN 2-3KFT BETWEEN 10-18Z TUESDAY. OTHERWISE CIGS
ARE LIKELY 4-5KFT WITH SOME CLEARING BY THE LATE AFTERNOON
HOURS.
KPDX AND APPROACHES...CLEAR SKIES WILL MOST LIKELY GIVE WAY TO
SOME VFR STRATUS IN THE MORNING HOURS. THAT SAID, CURRENT
GUIDANCE ONLY GIVES A 20-30% CHANCE FOR A BROKEN OR OVERCAST LOW
STRATUS DECK WITH CEILINGS BETWEEN 2000-3000 FT BETWEEN 11-18Z
TUESDAY. -99/23
MARINE
BUOY OBSERVATIONS FROM EARLY MONDAY AFTERNOON SHOWED
SIGNIFICANT WAVE HEIGHTS OF 4 TO 5 FT WITH SOUTHERLY WINDS
GENERALLY RANGING BETWEEN 5 AND 15 KT, STRONGEST OVER THE
NORTHERN WATERS. THERE ARE TWO SEPARATE SWELLS ONGOING, WITH A
SHORT PERIOD NORTHWEST SWELL AND A LONG PERIOD SOUTHWEST SWELL
DOMINATING THE CURRENT SEA STATE. GIVEN THE LOW SWELL HEIGHTS
AND RELATIVELY WEAK WINDS, THERE ARE NO HEADLINES IN EFFECT OVER
THE COASTAL WATERS AT THIS TIME.
VERY LITTLE CHANGE IS EXPECTED TO THE OVERALL SEA STATE THROUGH
FRIDAY. HOWEVER, THE WIND DIRECTION WILL CHANGE FROM SOUTHERLY TO
NORTHERLY BY LATE TUESDAY AFTERNOON IN THE WAKE OF A WEAK FRONTAL
PASSAGE. NORTH WINDS ARE THEN EXPECTED TO CONTINUE THROUGH FRIDAY.
WINDS BECOME MORE NORTHWESTERLY ON SATURDAY WITH WIND GUSTS
INCREASING TO AROUND 15-20 KT, AND THEN VEER BACK TO THE NORTH ON
SUNDAY WITH GUSTS INCREASING TO 20-25 KT. WINDS WILL BE STRONGEST
DURING THE AFTERNOON AND EVENING HOURS OVER THE CENTRAL AND
SOUTHERN WATERS. CONFIDENCE IN SMALL CRAFT ADVISORY LEVEL WIND
GUSTS OVER 21 KT ON SUNDAY IS HIGH, AS PROBABILITIES FOR MAX GUSTS
OF THIS MAGNITUDE RANGE BETWEEN 70-90% OVER THE CENTRAL AND
SOUTHERN WATERS. PROBABILITIES ARE RELATIVELY LOWER OVER THE
NORTHERN WATERS, RANGING BETWEEN 50-65%. -23
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
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