382
FXUS66 KPQR 252153
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
253 PM PDT TUE AUG 25 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 80S TODAY BEFORE DROPPING INTO THE 70S
LATER THIS WEEK. INCREASING ONSHORE FLOW WILL BRING A STRONGER
PUSH OF MARINE AIR INTO THE INTERIOR TONIGHT INTO WEDNESDAY.
COOLER AND MORE UNSETTLED CONDITIONS ARE FAVORED INTO THE
WEEKEND, WITH PERIODIC FRONTAL PASSAGES BRINGING LOW
PRECIPITATION CHANCES.
DISCUSSION...NOW THROUGH MONDAY
A BROAD TROUGH OVER THE
NORTHEAST PACIFIC IS BEGINNING TO SHIFT EASTWARD TOWARDS THE
PACIFIC NORTHWEST, RESULTING IN A TREND TOWARDS MODEST COOLING
TEMPERATURES. TODAY IS THE ONLY EXCEPTION, WITH HIGH
TEMPERATURES GENERALLY IN THE MID TO UPPER 80S ACROSS THE
INTERIOR LOWLANDS AND 60S ALONG THE COAST. ONSHORE FLOW WILL
BECOME INCREASINGLY ESTABLISHED THIS AFTERNOON AND EVENING, WITH
WINDS TURNING WESTERLY AS A STRONGER MARINE PUSH DEVELOPS
TONIGHT. MARINE AIR SHOULD SPREAD INLAND THROUGH THE OVERNIGHT
HOURS, WHILE ANY LINGERING WILDFIRE SMOKE IS DISPLACED EAST OF
THE CASCADES BY WEDNESDAY. ALONG WITH THIS MARINE PUSH, FOG MAY
PUSH INTO THE COAST AS A RESULT OF FOG FORMATION OVER THE OCEAN,
BRINGING A POTENTIAL REDUCTION OF VISIBILITY, PRIMARILY NEAR
THE COASTLINE.
THE UPPER TROUGH WILL CONTINUE PROGRESSING TOWARD THE PACIFIC
NORTHWEST ON WEDNESDAY, WITH THE AXIS SHIFTING FARTHER NORTHEAST
AND BRINGING ADDITIONAL COOLING. INCREASING ONSHORE INFLUENCE
SHOULD RESULT IN AREAS OF LOW STRATUS ACROSS THE INTERIOR
LOWLANDS WEDNESDAY MORNING, WHICH WILL LIMIT AFTERNOON WARMING.
HIGHS ARE EXPECTED TO REACH THE LOWER 80S INLAND, WITH COOLER
CONDITIONS ALONG THE COAST.
THE BROADER PATTERN REMAINS FAVORABLE FOR CONTINUED TROUGHING
ACROSS THE PACIFIC NORTHWEST THROUGH THE LATTER HALF OF THE
WEEK. SEVERAL SMALLER-SCALE DISTURBANCES ARE EXPECTED TO ROTATE
THROUGH THE TROUGH, REINFORCING THE COOLER REGIME. TEMPERATURES
SHOULD CONTINUE TRENDING DOWNWARD, WITH THE POTENTIAL FOR
ADDITIONAL MARINE PUSHES AND INCREASING CLOUD COVER. PRECIPITATION
CHANCES REMAIN RELATIVELY LIMITED BUT ARE EXPECTED TO INCREASE
SOMEWHAT AS THE PATTERN BECOMES MORE ACTIVE. A WEAK FRONTAL
PASSAGE IS POSSIBLE THURSDAY, FOLLOWED BY ANOTHER WEAK FRONT
SATURDAY, WITH PRECIPITATION CHANCES GENERALLY AROUND 10-20%.
NEITHER SYSTEM APPEARS PARTICULARLY WET AT THIS POINT, THOUGH
TIMING AND STRENGTH WILL BE REFINED AS THE WEEK PROGRESSES.
BY LATE WEEKEND, ENSEMBLE GUIDANCE SUGGESTS THE UPPER-LEVEL
PATTERN BEGINS TO FLATTEN, WHICH COULD ALLOW TEMPERATURES TO
REBOUND TOWARD THE 80S. HOWEVER, ENSEMBLE GUIDANCE ALSO SUGGESTS
A BROAD TROUGH MAY DIG SOUTH INTO THE PNW MONDAY INTO TUESDAY,
BRINGING A POSSIBILITY OF MORE RAIN. CONFIDENCE IS LOWER DURING
THIS PORTION OF THE FORECAST AS THE EVOLUTION OF THE TROUGH AND
EMBEDDED DISTURBANCES REMAINS SOMEWHAT UNCERTAIN. ~12
AVIATION...THROUGH 21Z WEDNESDAY
DRY, SOUTHWEST FLOW ALOFT
TODAY AS UPPER LEVEL RIDGE OF HIGH PRESSURE SHIFTS EAST. SATELLITE
IMAGERY THIS AFTERNOON SHOWS MARINE STRATUS BREAKING UP ALONG THE
COAST, WHILE TERMINAL OBSERVATIONS SHOW A MIX OF MVFR TO VFR CIGS
WITH THE LINGERING STRATUS DECKS. EXPECT MARINE STRATUS TO FILL
BACK IN AT COASTAL LOCATIONS THIS EVENING BY 00-02Z THU WITH
CONDITIONS DETERIORATING ANYWHERE FROM LOW-END MVFR TO LIFR. BEST
CHANCES FOR LIFR CONDITIONS WILL BE AT KONP (40-50% CHANCE) WHERE
VIS MAY ALSO BE REDUCED DUE TO FOG OVERNIGHT.
WILDFIRE SMOKE FROM THE AUSTIN FIRE WILL CONTINUE TO SHIFT EAST
OF PDX LATER THIS AFTERNOON AS A STRONG MARINE PUSH OF WESTERLY
WINDS ARRIVES. VFR CONDITIONS ARE EXPECTED ACROSS INLAND
TERMINALS THROUGH AT LEAST 10Z WEDNESDAY. THERE IS AROUND A 30-50%
CHANCE THAT MARINE STRATUS WITH MVFR CIGS PUSHES INLAND AFTER
12-14Z WED MORNING. EXPECT SOUTHWEST WINDS TO BECOME SLIGHTLY MORE
WESTERLY THIS AFTERNOON BEFORE EASING LATER THIS EVENING.
KPDX AND APPROACHES...VFR CONDITIONS EXPECTED WITH SMOKE ALOFT
GRADUALLY DRIFTING EASTWARD THIS AFTERNOON. WITH A STRONGER
MARINE PUSH TONIGHT, MARINE STRATUS COULD PUSH INLAND WITH AROUND
A 30-50% CHANCE OF MVFR CIGS AFTER 14Z WEDNESDAY. SSW WINDS AROUND
4-7 KT EXPECTED TO BECOME WESTERLY AFTER 22Z. /DH
MARINE
A WEAK MESO-LOW IS MOVING UP THE NORTH OREGON COAST THIS
AFTERNOON BRINGING GUSTY SOUTH-SOUTHWEST WINDS TO THE INNER
WATERS. WILL MAINTAIN THE SMALL CRAFT ADVISORY FOR GUSTS UP TO 25
KT FOR THE INNER WATERS NORTH OF CAPE FALCON AND THE COLUMBIA
RIVER BAR THROUGH 7 PM THIS EVENING. OTHERWISE, HIGH PRESSURE WILL
BUILD NORTH ALONG THE COAST TONIGHT AS LOW PRESSURE WELL OFFSHORE
WEAKENS AS IT MOVES NORTHEAST TOWARD VANCOUVER ISLAND THROUGH
WEDNESDAY NIGHT. SOUTHERLY WINDS EASE OVERNIGHT BEFORE INCREASING
AGAIN ON WEDNESDAY AS A WEAK FRONT APPROACHES THE OUTER WATERS.
ANOTHER WEAK FRONT APPROACHES THE INNER WATERS THURSDAY MORNING,
BRIEFLY INCREASING SOUTHERLIES AGAIN, BUT IN GENERAL, WINDS ARE
EXPECTED TO REMAIN BELOW 20 KT.
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. /DH
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 7 PM PDT THIS EVENING FOR PZZ210-251.
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