267
FXUS66 KPQR 181721
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1021 AM PDT SUN OCT 18 2026
UPDATED AVIATION DISCUSSION.
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 18Z MONDAY
LARGELY VFR CONDITIONS FAVORED
ACROSS THE AIRSPACE THROUGHOUT THE PERIOD. PATCHY FOG OR LOW
CLOUDS THIS MORNING IS YIELDING AREAS OF MVFR/IFR VIS/CIGS AS OF
17Z SUN, MOST NOTABLY ALONG THE EASTERN WILLAMETTE VALLEY AND
CASCADE FOOTHILLS INCLUDING AT KPDX/KTTD. CONDITIONS ARE
EXPECTED TO IMPROVE BACK TO VFR BY 19-20Z SUN AS LOW CLOUD
RAPIDLY MIX OUT THIS MORNING. VFR CONDITIONS THEN PREVAIL WITH
INCREASING HIGH CLOUD COVERAGE THROUGH MUCH OF THE DAY. CIGS
FALL BELOW 5-10 KFT AFTER 06Z MON AS A WEATHER SYSTEM WELL
OFFSHORE MAKES ITS NEAREST APPROACH. WINDS WILL RISE OUT OF THE
NORTH TO NORTHWEST AT 5-10 KT THIS AFTERNOON, THEN EASE AND BACK
OUT OF THE SOUTH TO SOUTHEAST TONIGHT.
KPDX AND APPROACHES...IFR VIS/CIGS FROM LOW CLOUDS AND MIST WILL
ERODE BY 19-20Z SUN WITH VFR CONDITIONS EXPECTED THEREAFTER.
HIGH CLOUDS INCREASE THROUGH SUNDAY, WITH CIGS LOWERING BELOW
5-10 KFT THROUGH TONIGHT. WINDS WILL RISE OUT OF THE NORTHWEST
TO AROUND 5 KT THIS AFTERNOON, THEN EASE AND BACK OUT OF THE
SOUTHEAST TONIGHT. -36
MARINE
A WESTERLY SWELL WILL CONTINUE TO MOVE INTO THE
WATERS, KEEPING SEAS IN THE 7-9 FOOT RANGE AT 11-12 SECONDS
THROUGH EARLY TONIGHT. NORTHERLY WINDS WILL GRADUALLY DECREASE
THROUGH THE DAY, DROPPING BELOW 10 KT TONIGHT. 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.
A WEATHER SYSTEM DROPPING SOUTHWARD OFF THE COAST MONDAY INTO
TUESDAY WILL GENERATE ANOTHER WESTERLY SWELL MOVING INTO THE
WATERS. THERE IS A 10-30% CHANCE FOR SEAS TO PUSH TO 10 FT
ACROSS THE WATERS, PARTICULARLY TUESDAY BEYOND 20 NM, WITH THE
HIGHEST CHANCES SOUTH OF CAPE FOULWEATHER UP TO 50%. THERE IS
ALSO A 40-70% CHANCE FOR WIND GUSTS TO CLIMB INTO THE 21-25 KT
RANGE TUESDAY. WINDS AND SEAS TREND DOWNWARD MIDWEEK WITH MORE
ACTIVE WEATHER LATE IN THE WORKWEEK. -19
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
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