545
FXUS66 KPQR 112059
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
159 PM PDT SUN OCT 11 2026
SYNOPSIS
GENERALLY DRY CONDITIONS PREVAIL THROUGH THE
UPCOMING WEEK AS WE PROGRESSES FURTHER INTO OCTOBER. CLEAR SKIES
AND COOL NIGHTS INCREASE CHANCES FOR FROST ACROSS A GOOD CHUNK
OF THE REGION TO START THE WEEK. TEMPERATURES TREND WARMER LATE
WEEK AS AN UPPER-LEVEL RIDGE AMPLIFIES OVER THE REGION.
ENSEMBLES HINT AT THE POTENTIAL RETURN OF SOME RAINFALL TOWARDS
THE END OF THE WEEKEND.
SHORT TERM...NOW THROUGH TUESDAY NIGHT
OUR DRY AUTUMN
CONDITIONS HAVE RETURNED AS AN UPPER-LEVEL LOW PRESSURE JUST
OVER THE CASCADES IN CENTRAL/EASTERN OREGON CONTINUES TO WEAKEN
AND SHIFT SOUTHWARD ALLOWING FOR RIDGING TO SLOWLY BUILD
OVERHEAD AND BROAD NORTHERLY FLOW TO PREVAIL. BEYOND SOME FAIR-
WEATHER CUMULUS OVER THE CASCADES THIS AFTERNOON, SATELLITE
IMAGERY DEPICTS CLEAR SKIES ACROSS NORTHWEST OREGON AND
SOUTHWEST WASHINGTON - THIS WILL COME INTO PLAY TONIGHT. ONCE WE
GET PAST SUNSET, THE AFOREMENTIONED CLEAR SKIES AND LIGHT WINDS
WILL SUPPORT RATHER EFFICIENT RADIATIONAL COOLING, AND DUE TO
OUR PROXIMITY TO THE UPPER-LEVEL LOW (SLIGHTLY COOLER AIRMASS
OVERHEAD), TEMPERATURES LIKELY DROP WELL BELOW NORMAL. GIVEN
THE PREVALENCE OF WIDESPREAD LOW TEMPERATURES IN THE MID 30S AND
CLEAR SKIES (EXTREMELY IMPORTANT VARIABLE FOR FROST WHEN 2
METER TEMPERATURES ARE 33-34+), HAVE ISSUED ANOTHER ROUND OF
FROST ADVISORIES FOR TONIGHT INTO MONDAY MORNING ACROSS THE
COAST RANGE/WILLAPA HILL VALLEYS, CASCADE FOOTHILLS, AND MOST OF
THE INTERIOR VALLEY AREAS AWAY FROM THE URBAN CENTER OF
PORTLAND AND LOCATIONS WITH POTENTIALLY TOO MUCH MODERATING
INFLUENCE FROM THE COLUMBIA RIVER. EVEN COLDER LOW TEMPERATURES
(28-32F) ARE ANTICIPATED IN THE UPPER HOOD RIVER VALLEY
PROMPTED THE ISSUANCE OF A FREEZE WARNING AS WELL. ANYONE
GROWING OUTDOOR PLANTS THAT ARE SUSCEPTIBLE TO FROST DAMAGER
SHOULD CONTINUE TO COVER PLANTS OR LEAVE PLANTS INDOORS IF
POSSIBLE.
AT LEAST DAYTIME TEMPERATURES THROUGH THE EARLY PORTION OF THE
WEEK REMAIN FAIRLY CLOSE TO NORMAL FOR THOSE WHO MAY NOT BE
PARTICULARLY THRILLED ABOUT OUR COOLER MORNINGS - HIGHS
GENERALLY RISE INTO THE MID 60S ACROSS THE INTERIOR LOWLANDS.
WHILE THE AIRMASS OVERHEAD SLOWLY MODERATES/WARMS THROUGH
TUESDAY, THE CONTINUATION OF CLEAR SKIES EACH NIGHT LEADS TO
ADDITIONAL CHANCES FOR FROST DEVELOPMENT AS MORNING LOWS DROP
INTO THE MID 30S TO NEAR 40. THE LOCATIONS MOST LIKELY SEE FROST
IMPACTS ARE VALLEY LOCATIONS NEAR THE BASE OF, OR WITHIN, THE
COAST RANGE AND CASCADES WHERE COOL AIR POOLS AFTER SINKING OFF
THE TERRAIN. WILL LIKELY NEED ADDITIONAL FROST ADVISORIES MONDAY
NIGHT INTO TUESDAY MORNING BUT WE'LL HAVE TO PAY CLOSE
ATTENTION TO CLOUD COVER GIVEN THE SOMEWHAT MARGINAL AND TOUCHY
NATURE OF THE SET-UP. -99
LONG TERM.... WEDNESDAY TO SATURDAY
COME THE MIDDLE OF THE
WEEK, THE MAJORITY OF ENSEMBLE MEMBERS ARE IN AGREEMENT WITH
UPPER-LEVEL RIDGING REMAINING SLIGHTLY OFFSHORE OF THE U.S.
WEST COAST BEFORE THE AXIS OF THIS RIDGE SLOWLY SHIFTS OVERHEAD
LATE WEEK. THIS WILL MAINTAIN MOSTLY DRY AND WARM CONDITIONS ON
WEDNESDAY, HOWEVER, WE COULD SEE SOME INCREASING CLOUD COVER AS
A SYSTEM RIDES THE NORTHERN PERIPHERY OF THE RIDGE AND HEADS
INTO NORTHERN WASHINGTON/BRITISH COLUMBIA. ENSEMBLES HAVE NUDGED
THE TRACK OF THIS SYSTEM A TOUCH FURTHER NORTH COMPARED TO
PREVIOUS RUNS WHICH HAS DROPPED PRECIPITATION CHANCES ALONG THE
SOUTH WASHINGTON COAST BELOW 10-15%. WILL ALSO NOTE THE
INCREASED CLOUD COVER WILL HELP TO TREND OUR LOW TEMPERATURES
SLIGHTLY HIGHER AND REDUCE THE THREAT FOR WIDESPREAD FROST
DEVELOPMENT.
THURSDAY AND FRIDAY WHEN THE UPPER-LEVEL RIDGE MOVES DIRECTLY
OVERHEAD, DAYTIME TEMPERATURES JUMP INTO THE 70S ACROSS
INTERIOR VALLEYS. OFFSHORE EASTERLY FLOW LIKELY DEVELOPS ACROSS
THE CASCADES AND IN THE COLUMBIA RIVER GORGE DURING THIS LATE
WEEK TIME-PERIOD TOO. HEADING INTO THE WEEKEND, THE UPPER RIDGE
GETS PUSHED FURTHER EAST BY UPPER-LEVEL TROUGHING COMING DOWN
FROM THE GULF OF ALASKA. THERE REMAINS UNCERTAINTY WITH THE
TIMING, POSITION, AND MAGNITUDE OF THE TROUGHING AT THIS POINT,
BUT WHAT WE CAN SAY WITH HIGHER CONFIDENCE IS THAT THIS PATTERN
WOULD RETURN COOLER TEMPERATURES AND CHANCES FOR PRECIPITATION
FOR THE WEEKEND INTO THE FOLLOWING WEEK. -99/10
AVIATION...THROUGH 18Z MONDAY
VFR CONDITIONS WITH MOSTLY CLEAR
SKIES EXPECTED ACROSS NW OR AND SW WA THROUGH THE TAF PERIOD DUE
TO BUILDING HIGH PRESSURE OVER THE REGION. NORTH/NORTHEASTERLY
WINDS TODAY, STRONGEST ALONG THE COAST AND CENTRAL/SOUTHERN
WILLAMETTE VALLEY AT 10-13 KT WITH GUSTS TO 20-25 KT. ELSEWHERE,
WINDS REMAIN AROUND 4-7 KT. WINDS DECREASE AFTER 02-04Z MON,
BECOMING LIGHT AND EASTERLY ALONG THE COAST AND VARIABLE INLAND.
BETWEEN 07-15Z MON, CLEAR SKIES AND CALM WINDS WILL SUPPORT
TEMPERATURES FALLING TOWARDS 33-36 DEGREES F ACROSS MUCH OF THE
AREA OUTSIDE OF THE PORTLAND METRO AND AS LOW AS 28-32 DEGREES F
IN THE UPPER HOOD RIVER VALLEY. LOCATIONS THAT ARE ABLE TO COOL
DOWN TO THESE TEMPERATURES MAY SEE FROST DEVELOPMENT ON METAL
SURFACES.
KPDX AND APPROACHES...VFR CONDITIONS EXPECTED THROUGH THE TAF
PERIOD. NORTHWESTERLY WINDS 4-7 KT TODAY, BECOMING LIGHT AND
VARIABLE BY 03-06Z MON. -03
MARINE
AS OF SUNDAY AFTERNOON, SEAS NORTH OF CAPE FALCON ARE
LESS THAN 6-7 FEET AND NOT FORECAST TO INCREASE INTO THE EVENING
HOURS. ADDITIONALLY, THE PERIOD IS FLUCTUATING BETWEEN 9 SECONDS
AND 21 SECONDS AT BUOY 46029 AS THE INCOMING HIGH PERIOD WESTERLY
SWELL TAKES OVER AT TIMES. BECAUSE SEAS ARE NOT AS STEEP AS
EXPECTED, THE SMALL CRAFT ADVISORY FOR ZONES PZZ271 AND PZZ251
HAVE BEEN CANCELLED. SEAS SOUTH OF CAPE FALCON ARE INCREASING TO
AROUND 8 FEET, THOUGH THE PERIODS ARE ALSO FLUCTUATING BETWEEN 9
SECONDS AND 21 SECONDS. HOWEVER, SINCE THE SEAS ARE HIGHER, THE
SMALL CRAFT ADVISORIES REMAIN IN EFFECT, THOUGH HAVE BEEN CUT BACK
TO EXPIRE AT 8 PM PDT WHEN THE HIGH PERIOD SWELL IS FORECAST TO
BECOME THE MAIN SWELL. THE SMALL CRAFT ADVISORY FOR THE COLUMBIA
RIVER BAR REMAINS IN EFFECT UNTIL 8 PM PDT DUE TO A STRONG EBB
INCREASING SEAS TO AROUND 7 TO 8 FEET, WITH THE EBB PEAKING AROUND
550 PM PDT TODAY. WINDS REMAIN NORTHERLY TODAY WITH GUSTS MAINLY
LESS THAN 15-20 KTS, THOUGH THERE WILL BE A FEW OCCASIONAL GUSTS
21-25 KTS SOUTH OF CAPE FOULWEATHER THROUGH THIS EVENING.
BENIGN MARINE CONDITIONS EXPECTED FOR THE REST OF THE WEEK. WINDS
GRADUALLY WEAKEN ON MONDAY AND REMAIN NORTHERLY THROUGH EARLY
TUESDAY MORNING. TUESDAY TO WEDNESDAY, WINDS TURN MORE
SOUTHWESTERLY AHEAD OF AN APPROACHING WEAK FRONT, BUT RETURN
NORTHERLY BY THE END OF THE WEEK. SEAS SUBSIDE TO 4 TO 6 FT AT 12
TO 15 SECONDS WITH WINDS REMAINING BELOW 15 KT. -03
PQR WATCHES/WARNINGS/ADVISORIES
OR...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM PDT MONDAY FOR
ORZ104-107-109-112>119-123>125.
FREEZE WARNING FROM MIDNIGHT TONIGHT TO 8 AM PDT MONDAY FOR
ORZ121.
WA...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM PDT MONDAY FOR
WAZ202-204>208.
PZ...SMALL CRAFT ADVISORY UNTIL 8 PM PDT THIS EVENING FOR PZZ210-
252-253-272-273.
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