370
FXUS66 KPQR 301058
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
358 AM PDT WED SEP 30 2026
SYNOPSIS
OVERALL EXPECT LITTLE IN THE WAY OF WEATHER IMPACTS
AS WE PROGRESS THROUGH THE NEXT 5 TO 7 DAYS WITH DRY CONDITIONS
HEAVILY FAVORED TODAY INTO NEXT WEEK. THAT SAID, WE'LL STILL
HAVE TO BE ON THE LOOKOUT FOR PATCHY MORNING FOG AT TIMES ACROSS
THE INLAND VALLEYS DEGRADING VISIBILITY. CONFIDENCE IS HIGH
TEMPERATURES EMBARK ON A WARMING TREND THROUGH THE WEEKEND.
DISCUSSION...TODAY THROUGH TUESDAY
DRY CONDITIONS ARE
EXPECTED REGION-WIDE TODAY AS OUR WEAK FRONTAL BOUNDARY FROM
YESTERDAY HAS PASSED WITH UPPER-LEVEL RIDGING SLOWLY BUILDING
OVERHEAD IN ITS WAKE. IF YOU ENJOY DRY AND SOMEWHAT WARMER FALL
CONDITIONS, YOU'RE IN FOR A TREAT MOVING FORWARD. ENSEMBLE
MEMBERS DEPICT HIGH PRESSURE OVER THE EASTERN PACIFIC MOVING
INLAND OVER THE NEXT FEW DAYS, PEAKING OVER THE PACNW ON
SATURDAY AND SUNDAY. THIS WILL LEAD TO A GRADUAL WARMING TREND
FOR THE AREA THROUGH THE WEEK AS WE GAIN A FEW DEGREE INCREASE
EACH DAY. DUE TO DECENT CLEARING DURING THE OVERNIGHT/MORNING
HOURS, LIGHT WINDS, AND A MORE PROMINENT TEMPERATURE INVERSION
DEVELOPING EACH NIGHT, PATCHY FOG DEVELOPMENT IS LIKELY,
ESPECIALLY IN OUR MORE PROTECTED VALLEY AREAS WITH A WATER
SOURCE. MORNING FOG WILL GREATLY REDUCE VISIBILITY WHEREVER
PRESENT. THE INTERIOR LOWLAND ARE EXPECTED SEE TEMPERATURES IN
THE LOW TO MID 70S TODAY AND THE MID TO UPPER 70S ON THURSDAY
AND FRIDAY. TEMPERATURES THEN WARM TO THE UPPER 70S TO LOW/MID
80S FOR SATURDAY AND SUNDAY FOR THE INTERIOR LOWLANDS, WITH
UPPER 60S TO LOW 70S ALONG THE COAST AND TERRAIN. BY MONDAY, THE
VAST MAJORITY OF ENSEMBLE MEMBERS INDICATE THE RIDGE AXIS
SHIFTS EAST OF WA AND OR, ALLOWING FOR INCREASED ONSHORE FLOW
AND TEMPERATURES TO BEGIN LOWERING AGAIN INTO THE 70S FOR THE
INTERIOR VALLEYS WITH DRY WEATHER CONTINUING.
UNDERNEATH THIS UPPER-LEVEL RIDGE PATTERN, ENSEMBLES INDICATE A
NEAR SURFACE THERMAL TROUGH DEVELOPS ALONG THE COAST ON FRIDAY
THROUGH THIS WEEKEND. THIS PATTERN IS EXPECTED TO CAUSE WINDS TO
SHIFT FROM THE ONSHORE (WESTERLY) PATTERN THE AREA HAS
GENERALLY BEEN OBSERVING OVER THE PAST COUPLE OF WEEKS TO
OFFSHORE (EASTERLY TO NORTHERLY). AT THIS TIME, PRESSURE
GRADIENTS DON'T LOOK TO BE VERY HIGH, PEAKING AT A -3MB TO -4MB
DIFFERENCE BETWEEN PDX AND DLS, SO WINDS AREN'T EXPECTED TO BE
STRONG. INSTEAD, EXPECT TO SEE A TYPICAL DIURNAL BEHAVIOR OF
WINDS BECOMING EASTERLY ON THE WEST SIDE OF TERRAIN (MAINLY
CASCADES, POTENTIALLY COAST RANGE PEAKS AS WELL) IN THE
OVERNIGHT TO MORNING HOURS AND INCREASING TO PEAK GUSTS UP TO
20-35 MPH. THEN, WINDS DECREASE OVER THE TERRAIN DURING THE DAY
AND INCREASE THROUGH THE VALLEY FROM THE NORTH IN THE AFTERNOON
HOURS - PEAK GUSTS UP TO 20 MPH. THE PROBABILITY OF WIND GUSTS
PEAKING ABOVE 30 MPH IS LESS THAN 10-25% EVERYWHERE EXCEPT FOR
THROUGH THE WESTERN COLUMBIA RIVER GORGE AND SURROUNDING TERRAIN
AT 50-65%, WHICH IS GENERALLY THE WINDIEST LOCATION DURING
OFFSHORE FLOW. AT LEAST CONFIDENCE IS MODERATE TO HIGH REGARDING
THE TRANSITION BACK TO ONSHORE FLOW SUNDAY NIGHT INTO MONDAY
WHICH WOULD BRING AN END TO THESE DRIER AND LOCALLY BREEZY
CONDITIONS. -99/03
AVIATION...THROUGH 12Z THURSDAY
EARLY THIS MORNING FLIGHT
CONDITIONS ARE A MIX ACROSS THE REGION WITH GENERALLY IFR TO
LIFR AT THE COAST DUE TO FOG, AND GENERALLY VFR/MVFR INLAND
ALTHOUGH FOG/LOW STRATUS IS BEGINNING TO EXPAND ACROSS THE
SOUTHERN WILLAMETTE VALLEY. EXPECT COASTAL TERMINALS TO REMAIN
IN THIS FOG/LOW STRATUS LAYER THROUGH A DECENT CHUNK OF THE
MORNING HOURS BEFORE CIGS LIFT AND SKIES GRADUALLY CLEAR OUT
LATE MORNING/MIDDAY. INLAND TERMINALS TREND TOWARDS MVFR CIGS
THIS MORNING, PERSISTING THROUGH 16-18Z BEFORE VFR CONDITIONS
RETURN. THE EXCEPTION TO THIS IS LIKELY KEUG WHERE FOG IS
ALREADY PRESENT - SIMILAR TRANSITION TO VFR CONDITIONS BY MIDDAY.
LIGHT WINDS INCREASE TO AROUND 5-10 KT FROM THE NORTH/NORTHWEST
AFTER 18Z FOR MOST TERMINALS.
KPDX AND APPROACHES...MVFR CONDITIONS LIKELY PERSIST THROUGH THE
MORNING HOURS BEFORE CLEARING OCCURS AROUND 18-19Z. HIGH
CONFIDENCE IN VFR CIGS BY 20-21Z AT THE LATEST. ANTICIPATE WNW
WINDS TO TURN MORE NORTHERLY MIDDAY THROUGH THE AFTERNOON -
GUSTS ONLY AROUND 8-12 KNOTS. -99
MARINE
EXPECT GENERALLY CALMER CONDITIONS TODAY AS POST-FRONTAL
NORTHERLY WINDS TAKE HOLD ACROSS THE COASTAL WATERS. ANOTHER WEAK
SYSTEM MAY APPROACH THE NORTHERN WATERS FROM THE WEST ON
THURSDAY, BUT IT LIKELY HOLDS NORTH AS IT MOVES TOWARD THE
WASHINGTON COAST THEN OUT OF THE REGION - WINDS LIKELY GAIN A
WESTERLY COMPONENT TEMPORARILY. NORTHERLY WINDS THEN RETURN
FRIDAY, LIKELY PERSISTING OVER THE WEEKEND INTO EARLY NEXT WEEK.
AS FAR AS WAVE HEIGHTS ARE CONCERNED, MID-PERIOD WEST-
NORTHWESTERLY SWELL OF 6 TO 8 FT AT 11-12 SECONDS CONTINUES TO
MOVE THROUGH THE COASTAL WATERS THIS MORNING WITH BUOY
OBSERVATIONS SHOWING SIGNIFICANT WAVE HEIGHTS AROUND 7 TO 9 FT.
SEAS LIKELY HOLD IN THIS RANGE INTO THE EVENING, THEN SEAS
GRADUALLY SUBSIDE TO AROUND 4 TO 6 FT LATER IN THE WEEK WITH NO
OTHER PROMINENT SWELLS OF NOTE AT THIS TIME. -99/DH
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
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