693
FXUS66 KPQR 181121
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
421 AM PDT SUN OCT 18 2026
SYNOPSIS
LARGELY DRY WEATHER EXPECTED THROUGH MIDWEEK WHILE
TEMPERATURES REMAIN NEAR TO ABOVE AVERAGE FOR MID-OCTOBER.
CHANCES FOR RAIN AND COOLER TEMPERATURES RAMP UP LATE IN THE
WORK WEEK.
DISCUSSION...NOW THROUGH SATURDAY
CLEAR SKIES AND LIGHT WINDS
HAVE ALLOWED TEMPERATURES TO COOL OFF INTO THE 40S THROUGHOUT
THE WILLAMETTE VALLEY AND INTO THE MID TO UPPER 30S IN SOME OF
THE TYPICAL COOL SPOTS. THE FROST ADVISORY FOR THE UPPER HOOD
RIVER VALLEY, COAST RANGE VALLEYS AND THE SW WA LOWLANDS REMAINS
IN PLACE AS OBSERVED TEMPERATURES CONTINUE TO COOL INTO THE MID
TO UPPER 30S. DESPITE A COOL START TO THE MORNING, TODAY SHOULD
TURN OUT TO BE A PLEASANT FALL DAY. CONDITIONS REMAIN DRY AS
WITH HIGHS TOPPING OUT IN THE MID TO UPPER 60S ACROSS THE
INTERIOR LOWLANDS AND UPPER 50S TO LOW 60S ALONG THE COAST.
AN APPROACHING TROUGH WILL BRING INCREASING MID AND UPPER LEVEL
CLOUD COVER DURING THE EVENING WHICH WILL HELP KEEP
TEMPERATURES A BIT WARMER TONIGHT. GOOD AGREEMENT AMONG THE
ENSEMBLES HEADING INTO MONDAY WITH THE APPROACHING TROUGH
ELONGATING AND PINCHING OFF INTO A CLOSED UPPER LOW THAT DRIFTS
SOUTHWARD TOWARD NORTHERN CALIFORNIA. PRECIPITATION CHANCES
REMAIN LOW OVER LAND WITH THE BEST CHANCE OVER THE LANE COUNTY
CASCADES AT 20%. COOLER AIR ASSOCIATED WITH THE TROUGH WILL
DROP HIGHS TO RIGHT AROUND NORMAL ON MONDAY WITH THE INTERIOR
LOWLANDS REACHING THE LOW 60S AND THE COASTAL AREAS THE UPPER
50S. MONDAY NIGHT WILL BRING MORE WIDESPREAD CHANCES FOR
OVERNIGHT LOWS IN THE 30S FOR MANY VALLEYS AWAY FROM THE CORE
URBAN CENTERS.
HEADING INTO THE MIDDLE OF THE WEEK, THE UPPER LOW WILL CONTINUE TO
DRIFT TOWARD CALIFORNIA WHILE HEIGHTS REBOUND LOCALLY. THIS WILL
KEEP CONDITIONS DRY AND WILL HELP TEMPERATURES JUMP BACK ABOVE
NORMAL INTO THE LOW 70S ACROSS THE INTERIOR LOWLANDS ON TUESDAY AND
WEDNESDAY. OVERNIGHT LOWS DROP INTO THE LOW 40S FOR MOST LOCATIONS
BUT THE TYPICAL COOL SPOTS MAY DROP INTO THE UPPER 30S. WILL NEED TO
WATCH TRENDS AND POTENTIAL FOR MORE FROST DEVELOPMENT. THE LATTER
HALF OF THE WEEK AGAIN TRENDS TOWARD COOLER TEMPERATURES AND MODEST
CHANCES FOR RAIN. CLUSTER ANALYSIS SHOWS GOOD AGREEMENT IN TROUGHING
DEVELOPING OVER THE GULF OF ALASKA AND DROPPING SOUTHEAST TOWARD THE
PACNW THURSDAY INTO FRIDAY. THIS PATTERN WOULD FAVOR A RETURN TO
NEAR NORMAL TEMPERATURES AND CHANCES FOR LIGHT PRECIPITATION.
NIGHTLY CHANCES FOR FROST CONTINUE WITHIN INLAND VALLEYS. TOWARD
THE END OF THE 7 DAY PERIOD, A MORE ROBUST TROUGH AND
ASSOCIATED SURFACE LOW COULD BRING MORE SIGNIFICANT RAINFALL TO
THE REGION NEXT WEEKEND. -19/36
AVIATION...THROUGH 06Z MONDAY
BREEZY NORTHERLY WINDS AT MANY TAF
SITES SHOULD CONTINUE TO DIMINISH OVERNIGHT. AS A BAND OF MID-HIGH
LEVEL CLOUDS CURRENTLY OVER THE REGION MOVES EAST OF THE AREA
BETWEEN 06-08Z, VALLEYS SHOULD BEGIN TO COOL OFF MORE EFFICIENTLY
WITH SOME PATCHY FOG AND LOW CLOUDS DEVELOPING IN MORE WIND
SHELTERED VALLEYS. THE PROBABILITY FOR IFR CONDITIONS TO DEVELOP BY
DAYBREAK IS HIGHEST AT KEUG WITH A 25-30% CHANCE AT ANY GIVEN HOUR
IN THE 13-17Z SUNDAY TIMEFRAME. THE PROBABILITIES ARE CLOSER TO 20%
FOR OTHER INLAND TAF SITES. WHATEVER FOG AND LOW CLOUDS DO DEVELOP
OVERNIGHT SHOULD LIFT AND SCATTER OUT RATHER QUICKLY ON SUNDAY, MOST
LIKELY IN THE 17-20Z SUNDAY TIMEFRAME.
KPDX AND APPROACHES...EXPECT MAINLY VFR CONDITIONS THROUGH 06Z
MONDAY. HOWEVER, CLEARING SKIES, DECREASING WINDS AND CURRENT
DEWPOINTS IN THE MID 40S WILL LEAD TO A THREAT OF SOME PATCHY FOG
AND LOW CLOUDS TRYING TO DEVELOP LATER TONIGHT IN THE VICINITY OF
THE AIRPORT. HOWEVER, THERE IS ONLY A 15-20% CHANCE AT ANY GIVEN
HOUR FOR IFR CONDITIONS AT THE TERMINAL BETWEEN 13-17Z SUNDAY SO
WILL KEEP THE TAF VFR FOR THE TIME BEING.
MARINE
NORTHERLY FLOW CONTINUES THROUGH THE WEEKEND. IN
ADDITION, NORTHERLY WIND GUSTS OF 20-25 KT ARE BEGINNING TO
OCCUR AT BUOY 50 AND ARE EXPECTED TO PERSIST FOR SEVERAL HOURS
SO A SMALL CRAFT ADVISORY WAS ISSUED FOR THE WATERS OFF THE
CENTRAL COAST OF OREGON. A BUILDING MID-PERIOD WEST-
NORTHWESTERLY SWELL WILL PUSH SEAS TO 8-9 FT AT 11-12 SECONDS
TONIGHT THROUGH SUNDAY. CHANCES FOR SEAS HIGHER THAN 10 FT ARE
ONLY ~10% BEYOND 30 NM NORTH OF CAPE LOOKOUT. THIS SWELL WILL
ALSO CONTINUE TO POSE A MODERATE RISK FOR SNEAKER WAVES ALONG
THE COAST; CAUTION SHOULD BE USED BY THOSE IN OR NEAR THE WATER
ALONG BEACHES THROUGH THIS WEEKEND.
ANOTHER WEATHER SYSTEM DROPPING SOUTHWARD OFF THE COAST MONDAY INTO
TUESDAY WILL GENERATE ANOTHER SWELL THAT PUSH INTO THE REGION. THERE
IS A 50% CHANCE FOR SEAS TO PUSH TO 10 FT ACROSS THE WATERS,
PARTICULARLY BEYOND 20 NM TUESDAY. IN ADDITION, THERE IS A >75%
CHANCE FOR WIND GUSTS TO CLIMB INTO THE 21-25 KT RANGE TUESDAY.
WINDS AND SEAS APPEAR TO TREND DOWNWARD MIDWEEK WITH MORE ACTIVE
WEATHER LATE IN THE WORK WEEK.
PQR WATCHES/WARNINGS/ADVISORIES
OR...FROST ADVISORY UNTIL 9 AM PDT THIS MORNING FOR ORZ104-105-121.
WA...FROST ADVISORY UNTIL 9 AM PDT THIS MORNING FOR WAZ205-208.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT EARLY THIS MORNING FOR
PZZ253-273.
WWW.WEATHER.GOV/PORTLAND
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