702
FXUS66 KPQR 171720
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1020 AM PDT SAT OCT 17 2026
UPDATED AVIATION DISCUSSION.
SYNOPSIS
A WEAK COLD FRONT MOVING THROUGH THE AREA WILL
BRING LIGHT RAIN CHANCES THROUGH THE MORNING WITH CONDITIONS
DRYING OUT IN THE AFTERNOON. HIGH PRESSURE RETURNS LATER TODAY,
KEEPING CONDITIONS DRY THROUGH SUNDAY. LOW CHANCES FOR RAIN ON
MONDAY AS A LOW PRESSURE SYSTEM LIKELY REMAINS WELL OFFSHORE.
SEASONABLE TEMPERATURES AND DRY WEATHER EXPECTED TUESDAY AND
WEDNESDAY BEFORE ANOTHER CHANCE FOR LIGHT RAIN RETURNS THURSDAY.
SHORT TERM...NOW THROUGH SUNDAY NIGHT
AN EMBEDDED SHORTWAVE
TROUGH PASSING TO THE NORTH CONTINUES TO MOVE EAST ACROSS
SOUTHERN BRITISH COLUMBIA, SENDING A COLD FRONT THROUGH THE
AREA. SATELLITE AND RADAR IMAGERY AS OF 3 AM DEPICTS A SHALLOW
FRONTAL PRECIPITATION BAND MOVING EAST ACROSS THE COAST RANGE
WHICH IS PRODUCING LIGHT RAIN. MEAN QPF VALUES ARE STILL
EXPECTED TO RANGE FROM A TRACE TO 0.10 INCH, GENERALLY NORTH OF
LINCOLN CITY AT THE COAST AND FROM THE PORTLAND METRO AREA
NORTHWARD. CONDITIONS EXPECTED TO DRY OUT BY THE AFTERNOON WITH
NORTHERLY WINDS BEHIND THE FRONT. COULD SEE SOME BREEZY WINDS IN
THE WILLAMETTE VALLEY, SOUTH OF SALEM WITH GUSTS AROUND 20-25
MPH AFTER 10 PM. HIGHS THIS AFTERNOON WILL BE CLOSER TO NORMAL,
TOPPING OUT IN THE MID TO UPPER 60S ACROSS THE INTERIOR VALLEYS.
CLEARING SKIES BEHIND THE FRONT WILL ALLOW FOR OVERNIGHT LOWS
TO DROP INTO THE UPPER 30S TO LOW 50S. SOME SHELTERED LOCATIONS
COULD SEE TEMPERATURES BRIEFLY DROP BELOW 37 BUT THESE
CONDITIONS ARE NOT EXPECTED TO BE WIDESPREAD. THE ONLY EXCEPTION
WILL BE THE UPPER HOOD RIVER VALLEY WHERE TEMPERATURES ARE
EXPECTED TO DROP BETWEEN 33 AND 36 DEGREES FOR SEVERAL HOURS
BETWEEN 11 PM TONIGHT AND 9 AM SUNDAY MORNING. A FROST ADVISORY
HAS BEEN ISSUED FOR THIS ZONE FOR THE AFOREMENTIONED TIMEFRAME.
DRY WEATHER EXPECTED ON SUNDAY AS FLOW ALOFT BECOMES MORE ZONAL
WITH THE PASSAGE OF THE SHORTWAVE TROUGH. HIGHS A DEGREE OR TWO
COOLER COMPARED TO THE DAY PRIOR, PEAKING IN THE MID 60S FOR
MOST INTERIOR LOWLANDS AND MID 50S TO LOW 60S ALONG THE COAST.
SUNDAY NIGHT INTO MONDAY MORNING WILL BRING ANOTHER CHANCE FOR
FROST IN THE UPPER HOOD RIVER VALLEY AND THE SOUTHERN WILLAMETTE
VALLEY AS LOWS COULD DROP INTO THE MID TO UPPER 30S. -19
LONG TERM...MONDAY THROUGH FRIDAY
LOOKING AT THE START OF
NEXT WEEK, ENSEMBLES CONTINUE TO SHOW GOOD AGREEMENT IN A ROBUST
LOW PRESSURE SYSTEM DEVELOPING OVER THE NORTHEAST PACIFIC.
MODEL TRENDS CONTINUE TO KEEP THIS LOW WELL OFFSHORE, MOVING
ALMOST PARALLEL TO THE PACNW COAST AND JUST OFFSHORE ALONG
CALIFORNIA INTO THE MIDDLE OF THE WEEK. CHANCES FOR RAIN HAVE
PLUMMETED TO LESS THAN 25% AND EVEN THEN, ONLY A SMALL PORTION
OF THE FORECAST AREA HAS THAT HIGH OF A CHANCE FOR RAIN.
ENSEMBLE CLUSTERS REMAIN IN DECENT AGREEMENT FOR THE UPPER LEVEL
LOW TO PERSIST NEAR THE CALIFORNIA COAST ON WEDNESDAY, WHILE
SHORTWAVE RIDGING NUDGES INTO THE PACNW. THERE IS HIGH
CONFIDENCE FOR DRY CONDITIONS TO PERSIST ACROSS THE AREA TUESDAY
THROUGH MID THURSDAY, WITH TEMPERATURES WARMING BACK INTO THE
MID TO UPPER 60S. MORE UNCERTAINLY RETURNS LATER NEXT WEEK AS
ANOTHER UPPER LEVEL TROUGH BEGINS TO DROP OUT OF THE GULF OF
ALASKA. CHANCES FOR RAIN INCREASE ON THURSDAY, THOUGH CURRENTLY
REMAIN LESS THAN 40%. -19/DH
AVIATION...THROUGH 18Z SUNDAY
A WEAK COLD FRONT STRADDLING
THE AIRSPACE WILL CONTINUE TO TRACK EASTWARD, EXITING BY THE
EARLY AFTERNOON. VERY LIGHT RAIN SHOWERS WITH LARGELY VFR CIGS
AND SCT LOW CLOUDS AT 1-3 KFT WILL LIKELY PREVAIL THROUGH 20-21Z
SAT. BEHIND THE BOUNDARY, SKIES ARE EXPECTED TO TREND CLEARER
ASIDE FROM SCT HIGH CLOUDS. NORTH TO NORTHWEST WINDS WILL RISE
TO AROUND 10 KT WITH GUSTS UP TO 20 KT ALONG THE COAST THIS
AFTERNOON, AS WELL AS IN THE SOUTHERN WILLAMETTE VALLEY BY THIS
EVENING, AND TO AROUND 5 KT ELSEWHERE.
KPDX AND APPROACHES...VFR CONDITIONS FAVORED TO PREVAIL
THROUGHOUT THE PERIOD WITH LOW CHANCES FOR MVFR CIGS WITH VERY
LIGHT RAIN SHOWERS BEFORE A FRONTAL BOUNDARY EXITS EASTWARD BY
21Z SAT. SCATTERED HIGH CLOUDS OTHERWISE EXPECTED WITH NORTHWEST
WINDS RISING TO AROUND 5 KT THIS AFTERNOON. -36
MARINE
WEST WINDS WILL VEER TO THE NORTHWEST TODAY BEHIND A
WEAK COLD FRONT. SEAS 5 TO 7 FEET AT 11 TO 12 SECONDS BUILD
TOWARD 8 TO 9 FEET TONIGHT. CHANCES FOR SIGNIFICANT WAVE HEIGHTS
TO BUILD TO 10 FEET REMAIN LOW AT 10-15% BEYOND 30 NM. THIS
SWELL WILL ALSO POSE A MODERATE RISK FOR SNEAKER WAVES ALONG THE
COAST WHILE OVERALL SEAS REMAIN RELATIVELY BENIGN; CAUTION
SHOULD BE USED BY THOSE IN OR NEAR THE WATER ALONG COASTAL
BEACHES THROUGH THIS WEEKEND.
AS ANOTHER WEATHER SYSTEM LOOKS TO TRACK SOUTHWARD WELL OFFSHORE
OF THE OREGON AND WASHINGTON COASTS EARLY NEXT WEEK, AND MAY BRING
A PERIOD OF STEEPER SEAS MONDAY INTO TUESDAY ALTHOUGH THE NEWEST
GUIDANCE HAS DECREASED SIGNIFICANTLY, BRINGING SEAS OF 7 TO 9 FEET AT
11-12 SECONDS MONDAY AFTERNOON AND EVENING. CHANCES FOR WAVE
HEIGHTS ABOVE 10 FEET ARE 20-40% FOR WATERS BEYOND 20 NM. -19/36
PQR WATCHES/WARNINGS/ADVISORIES
OR...FROST ADVISORY FROM 11 PM THIS EVENING TO 9 AM PDT SUNDAY FOR
ORZ121.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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