551
FXUS66 KPQR 261124
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
424 AM PDT WED AUG 26 2026
SYNOPSIS
A GRADUAL COOLING TREND IS UNDERWAY ACROSS THE
PACIFIC NORTHWEST AS AN UPPER-LEVEL TROUGH DEVELOPS OFFSHORE.
INTERIOR LOWLAND HIGHS WILL REMAIN IN THE LOW 80S TODAY BEFORE
DROPPING INTO THE 70S TO END THE WEEK. INCREASING ONSHORE FLOW
WILL BRING A STRONGER PUSH OF MARINE AIR INTO THE INTERIOR
TODAY. COOLER AND MORE UNSETTLED CONDITIONS ARE FAVORED INTO
THE WEEKEND, WITH PERIODIC FRONTAL PASSAGES BRINGING LOW
PRECIPITATION CHANCES.
DISCUSSION...NOW THROUGH TUESDAY
UPPER LEVEL TROUGHING
ACROSS THE NORTHEAST PACIFIC WILL SLOWLY SHIFT EASTWARD TOWARD
WESTERN CANADA AND THE PACNW TODAY, SUPPORTING LOWERING HEIGHTS
AND COOLER TEMPERATURES. INCREASING ONSHORE FLOW IS EXPECTED TO
BRING MARINE STATUS TO THE INTERIOR LOWLANDS EARLY THIS MORNING
WILL AID IN KEEPING AFTERNOON HIGHS NEAR THE SEASONAL AVERAGE IN
THE LOW 80S INLAND AND 60S ALONG THE COAST. LOW CLOUD COVER
ACROSS THE INTERIOR IS EXPECTED TO BREAK UP LATE IN THE MORNING
WITH STRATUS OVER THE COAST LINGERING INTO THE AFTERNOON HOURS.
ANOTHER MARINE STRATUS PUSH INTO THE INTERIOR IS EXPECTED TONIGHT
INTO THURSDAY MORNING AS ONSHORE FLOW CONTINUES. A SHORTWAVE
EMBEDDED WITHIN THE LARGER UPPER LEVEL TROUGH WILL PASS OVERHEAD
EARLY THURSDAY, SENDING A WEAK COLD FRONT THROUGH THE AREA.
CHANCES FOR MEASURABLE PRECIPITATION VARY ACROSS THE AREA WITH
THE BEST CHANCES OVER THE COAST, COAST RANGE, AND CASCADE
FOOTHILLS. CHANCES OVER THESE AREA ARE 10-30% WITH LOCALLY
HIGHER CHANCES OVER PACIFIC COUNTY IN WA AT 40-60%. ELSEWHERE,
CHANCES ARE 5% OR LESS. THE DOWNWARD TREND IN HIGHS CONTINUES
WITH TEMPERATURES LIKELY TOPPING OUT IN THE UPPER 70S ACROSS THE
INTERIOR LOWLANDS WHILE THE COAST REMAINS IN THE 60S.
THE PATTERN REMAINS VERY SIMILAR HEADING INTO FRIDAY. UPPER LEVEL
TROUGHING PERSISTS WITH NORTHERLY ONSHORE AT THE SURFACE SUPPORTING
MARINE STRATUS DURING THE MORNING AND AFTERNOON HIGH TEMPERATURES IN
THE UPPER 70S. HEADING INTO SATURDAY, TROUGHING PERSISTS BUT A
REINFORCING DISTURBANCE COULD BRING A BETTER CHANCE FOR
PRECIPITATION. PROBABILITIES FOR MEASURABLE RAINFALL (0.01
INCHES) ARE 15-30% FOR AREAS NORTH OF SALEM. HOWEVER, MODELS
STILL SHOW A GOOD AMOUNT OF UNCERTAINTY.
THE PATTERN BEGINS TO FLATTEN OUT DURING THE SECOND HALF OF THE
WEEKEND WHICH WOULD ALLOW TEMPERATURES TO REBOUND TOWARD THE 80S.
ENSEMBLE CLUSTERS FAVOR A COOLER, POSSIBLY WET PATTERN HEADING INTO
EARLY TO MIDDLE OF NEXT WEEK. MEMBERS DO NOT SHOW A CLEAR "SLAM
DUNK" SCENARIO WITH WIDE VARIABILITY IN TIMING AND STRENGTH OF
UPPER LEVEL TROUGHING THAT DEVELOPS. -19
AVIATION...THROUGH 12Z THURSDAY
MVFR STRATUS ALONG THE COAST
IS EXPECTED TO PERSIST WHILE SPREADING INLAND. STRATUS IS
BEGINNING TO SHOW UP ON SATELLITE ACROSS THE LOWER COLUMBIA AND
WESTERN PORTLAND METRO. PROBABILITIES ARE EXPECTED TO PEAK BY
15-16Z THIS MORNING. AT TERMINALS ALONG THE I-5 CORRIDOR,
CHANCES FOR MVFR CIGS REACH 50-70% IN THE LOWER COLUMBIA
VALLEY, PORTLAND AREA, AND SOUTHERN WILLAMETTE VALLEY.
CONFIDENCE IS LOWER (30-50% CHANCE OF MVFR CIGS) IN THE CENTRAL
WILLAMETTE VALLEY (KSLE, KUAO, KMMV) WHERE CLOUD COVERAGE MAY BE
LOWER. LOW CLOUDS WILL MIX OUT BY 18-19Z WED INLAND, YIELDING A
RETURN TO VFR CONDITIONS, WHILE MORE PERSISTENT LOW CLOUDS AT
2-3 KFT MAY SEE MVFR CONDITIONS LINGER LATER ON THE COAST. WINDS
5-10 KT OUT OF THE SOUTHWEST AND VEER MORE WESTERLY THROUGH MUCH
OF THE DAY, BEFORE EASING WEDNESDAY EVENING. STRENGTHENED
ONSHORE FLOW SHOULD KEEP SMOKE FROM FIRES IN THE CASCADES AND
ATTENDANT VIS RESTRICTIONS TO THE EAST OF AREA TERMINALS.
KPDX AND APPROACHES...VFR CONDITIONS EXPECTED TO PREVAIL THROUGH
12-14Z TODAY, WHEN LOW CLOUDS REACHING INLAND ALONG THE
COLUMBIA RIVER WILL INCREASE THE CHANCES FOR MVFR CIGS, WHICH
REACH 50-70% FROM 14-18Z BEFORE CLOUD COVER DECREASES AS LOW
CLOUDS MIX OUT BY THE AFTERNOON. SOUTH WINDS AROUND 5 KT AND
VEER OUT OF THE SOUTHWEST TO WEST LATER TODAY. -19/36
MARINE
SOUTHERLY WINDS EXPECTED TODAY WITH SPEEDS 10-15 KT
AND GUSTS LESS THAN 20KT, WEAKENING TONIGHT. ANOTHER WEAK FRONT
APPROACHES THE INNER WATERS THURSDAY MORNING, BRIEFLY INCREASING
SOUTHERLIES, BUT IN GENERAL, WINDS ARE EXPECTED TO REMAIN BELOW
20 KT. COULD SEE A BRIEF PERIOD OF ISOLATED GUSTS UP TO 25 KT
ACROSS THE INNER WATERS NORTH OF CAPE FALCON AND AROUND THE
COLUMBIA RIVER BAR BETWEEN 8 AM AND 2 PM. WILL HOLD OFF ON ANY
SMALL CRAFT ADVISORIES AT THIS TIME GIVEN THE SHORT WINDOW AND
ISOLATED NATURE.
HIGH PRESSURE BEGINS TO REBUILD OVER THE WATERS LATER THURSDAY
INTO FRIDAY RETURNING NORTH TO NORTHWEST WINDS ACROSS THE COASTAL
WATERS INTO THE WEEKEND. PREDOMINATELY WIND DRIVEN SEAS ARE
EXPECTED TO REMAIN AROUND 3 TO 6 FT THROUGH THE WEEKEND. SOMEWHAT
MORE ACTIVE PATTERN MAY RETURN EARLY NEXT WEEK. -19/DH
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
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X.COM/NWSPORTLAND
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