421
FXUS66 KPQR 102045
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
145 PM PDT SAT OCT 10 2026
SYNOPSIS
WEAK LOW PRESSURE OVER THE REGION WILL MAINTAIN
COOL TEMPERATURES WITH VERY LIGHT SCATTERED SHOWERS PERSISTING
THROUGH THE EVENING. HIGH PRESSURE RE-BUILDS SUNDAY TO MONDAY,
RETURNING DRY AND SUNNY CONDITIONS. COOL NIGHTS WILL BRING
CHANCES FOR MORNING FROST IN RURAL VALLEYS AWAY FROM URBAN CORES
THIS WEEKEND INTO EARLY NEXT WEEK. NEXT CHANCES FOR LIGHT RAIN
ARRIVE TUESDAY TO WEDNESDAY. TEMPERATURES TREND WARMER LATE IN
THE WEEK AS AN UPPER-LEVEL RIDGE AMPLIFIES OVER THE REGION.
SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
LINGERING LIGHT
SHOWERS ARE EXPECTED TO CONTINUE TO DISSIPATE AS HIGH PRESSURE
BUILDS OVER THE REGION THROUGH TONIGHT. AS HIGH PRESSURE BUILDS,
EXPECT SKIES TO SLOWLY CLEAR AND TEMPERATURES TO COOL. LIGHT
WINDS, CLEAR SKIES AND COOL, OVERNIGHT LOWS WILL RESULT IN THE
POTENTIAL FOR FOG AND FROST DEVELOPMENT TONIGHT. AS SUCH, WILL
MAINTAIN THE CURRENT FROST ADVISORY TONIGHT THROUGH SUNDAY
MORNING AS MORE WIDESPREAD AND IMPACTFUL FROST HAS A HIGHER
PROBABILITY OF DEVELOPING. THERE IS HIGH CONFIDENCE FOR FROST
AND MORNING LOWS BETWEEN 33-36 DEGREES F OVER THE UPPER HOOD
RIVER VALLEY, CASCADE FOOTHILLS, NORTH OREGON COAST RANGE
VALLEYS, BATTLE GROUND/BRUSH PRAIRIE AREA, AND PORTIONS OF THE
CENTRAL/SOUTHERN WILLAMETTE VALLEY TO THE EAST OF THE I-5
CORRIDOR NEAR THE FOOTHILLS (E.G. LEBANON, SCIO, ALBANY, HALSEY,
BROWNSVILLE, SWEET HOME, MARCOLA, MOHAWK, JASPER). SUB-FREEZING
TEMPERATURES LESS THAN 32 DEGREES ARE LIKELY IN DEE AND
PARKDALE (70-90% CHANCE). ANYONE GROWING OUTDOOR PLANTS THAT ARE
SUSCEPTIBLE TO FROST DAMAGE SHOULD COVER PLANTS OR MOVE PLANTS
INDOORS IF POSSIBLE.
EXPECT DRY AND SUNNY CONDITIONS SUNDAY TO MONDAY AS UPPER-LEVEL
RIDGING AMPLIFIES OVER THE PACIFIC NORTHWEST, WARMING
TEMPERATURES INTO THE MID TO UPPER 60S. WILL CONTINUE TO SEE
CHANCES FOR FROST DEVELOPMENT EACH NIGHT THROUGH MONDAY
NIGHT/TUESDAY MORNING AS CLEAR SKIES AND CALM WINDS SUPPORT
RADIATIONAL COOLING, ESPECIALLY IN RURAL AREAS AND SHELTERED
VALLEYS. THESE AREAS WILL LIKELY (50-60%) EXPERIENCE
TEMPERATURES INTO THE MID 30S EACH MORNING. /42-10
LONG TERM...TUESDAY THROUGH SATURDAY
HIGH PRESSURE WILL
MAINTAIN MOSTLY DRY CONDITIONS WITH SEASONABLE TEMPERATURES
THROUGH WEDNESDAY. AN EXCEPTION WOULD BE SOUTHWEST WASHINGTON
AND THE NORTH OREGON COAST RANGE AND CASCADES, WHERE CHANCES FOR
LIGHT RAIN INCREASE TO 10-30% AS A WEAK COLD FRONT OVER THE
COASTAL WATERS ATTEMPTS PUSHING INLAND. EVEN IF THIS FRONT IS
ABLE TO MOVE INLAND, IT WOULD BE DECAYING, WHICH SUGGESTS RAIN
AMOUNTS WOULD LIKELY BE VERY LIGHT IF ANY PRECIPITATION IS
OBSERVED. CHANCES FOR 48 HOUR RAIN TOTALS EXCEEDING 0.10 INCH
FROM 5 AM TUESDAY TO 5 AM THURSDAY ARE 15-30% ACROSS SOUTHWEST
WASHINGTON AND THE NORTH OREGON COAST RANGE AND CASCADES, AND
5-10% ACROSS THE WILLAMETTE VALLEY. WILL ALSO SEE INCREASED
CLOUD COVER BY WEDNESDAY FROM THIS WEAK FRONT, WHICH WILL KEEP
OVERNIGHT TEMPERATURES WARMER AND REDUCE THE THREAT OF
WIDESPREAD FROST BY TUESDAY NIGHT/WEDNESDAY MORNING.
THURSDAY AND FRIDAY, THE MAJORITY OF ENSEMBLE MEMBERS ARE IN
AGREEMENT THAT UPPER-LEVEL RIDGING WILL AMPLIFY AGAIN OVER THE
WESTERN CONUS. THIS WILL RESULT IN TEMPERATURES REBOUNDING TO
THE LOW TO MID 70S ACROSS INTERIOR VALLEYS AT THE END OF THE
WEEK. BY NEXT WEEKEND, THE RIDGE OF HIGH PRESSURE LOOKS TO BE
PUSHED EASTWARD BY A BROAD AREA OF LOW PRESSURE COMING FROM THE
GULF OF ALASKA. HOWEVER, THERE IS SOME UNCERTAINTY IN THE
CLUSTERS. LOOKING AT THE 500 MB WPC CLUSTERS, CLUSTERS 1 AND 3
ARE LEANING TOWARDS THE LOW WITH A COMBINER PROBABILITY OF 59%.
CLUSTERS 2 AND 4 FAVOR THE UPPER LEVEL RIDGE PERSISTING WITH A
COMBINED PROBABILITY OF 41%. SO, WHILE A SLIGHTLY COOLER SOLUTION
IS SOMEWHAT FAVORED, IT IS BY NO MEANS A SURE THING. /42-10
AVIATION...THROUGH 18Z SUNDAY
RADAR IMAGERY CONTINUES TO SHOW
LIGHT, SCATTERED SHOWERS ACROSS THE AIRSPACE AS WEAK LOW PRESSURE
REMAINS OVER THE REGION. THESE SHOWERS ARE EXPECTED TO LINGER
THROUGH AROUND 00Z SUNDAY, BUT AM NOT EXPECTING ANY IMPACTS FROM
THESE SHOWERS. THEREFORE, EXPECT PREDOMINATELY VFR CONDITIONS
ACROSS THE AIRSPACE THROUGH THE MAJORITY OF THE TAF PERIOD. HIGH
PRESSURE WILL SLOWLY RE-BUILD THROUGH DAYTIME HOURS WHICH WILL
BRING A RETURN OF DRIER CONDITIONS ALONG WITH CLEARING SKIES.
NORTHWESTERLY WINDS AROUND 3-7 KT FOR ALL TERMINALS TODAY.
TONIGHT, CLEARING SKIES AND CALM WINDS WILL SUPPORT TEMPERATURES
FALLING TOWARDS 33-36 DEGREES F FOR MORE RURAL AREAS AND
SHELTERED VALLEYS. AREAS THAT ARE ABLE TO COOL DOWN TO THESE
TEMPERATURES MAY SEE FROST DEVELOPMENT ON METAL SURFACES. COULD
ALSO SEE SOME IFR/LIFR CONDITIONS DEVELOPING BETWEEN KSLE AND KEUG
STARTING AROUND 12Z SUNDAY. ANY LOWERED FLIGHT CONDITIONS THAT DO
MANIFEST ARE EXPECTED TO IMPROVE TOWARDS VFR AROUND 17Z-19Z
SUNDAY.
KPDX AND APPROACHES...VFR WITH VERY LIGHT SHOWERS THROUGH AROUND
00Z SUNDAY. SKIES EXPECTED TO CLEAR THROUGH THE DAYTIME WHICH WILL
RESULT IN COOLER OVERNIGHT TEMPERATURES. NORTHWESTERLY WINDS 3-5
KT. /42
MARINE
TONIGHT THROUGH AT LEAST MONDAY MORNING, SMALL CRAFT
CONDITIONS WILL CONTINUE ACROSS ALL WATERS. WHILE A RENEWED ROUND
OF BREEZY NORTH/NORTHEASTERLY WINDS WITH GUSTS UP TO 20 KT ARE
EXPECTED TO DEVELOP TONIGHT THROUGH SUNDAY EVENING, STEEP AND
CHOPPY SEAS AROUND 8-10 FT AT 9-11 SECONDS WILL PERSIST. AS SUCH,
WILL MAINTAIN A SMALL CRAFT ADVISORY THROUGH AT LEAST EARLY MONDAY
MORNING. WINDS WEAKEN ON MONDAY BUT WILL REMAIN NORTHERLY THROUGH
EARLY TUESDAY MORNING, BEFORE TURNING MORE SOUTHWESTERLY BY THE
MIDDLE OF THE WEEK AHEAD OF AN APPROACHING WEAK FRONT. SEAS ARE
ALSO EXPECTED TO ALSO SUBSIDE TOWARDS 5-7 FT BY MONDAY WITH WINDS
REMAINING BELOW 15 KT. RELATIVELY BENIGN CONDITIONS THROUGH THE
MAJORITY OF THE WEEK. /42
PQR WATCHES/WARNINGS/ADVISORIES
OR...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM PDT SUNDAY FOR
ORZ104-106-113-117-121-123>125.
WA...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM PDT SUNDAY FOR
WAZ205-208.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT MONDAY FOR PZZ210-251>253-
271>273.
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