840
FXUS66 KPQR 102250
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
250 PM PST MON NOV 10 2025
SYNOPSIS
A WEAK SHORTWAVE TROUGH CONTINUES TO PASS THROUGH THE REGION
TODAY, BRINGING SCATTERED LIGHT SHOWERS AND MID-LEVEL CLOUDS
ACROSS NORTHWEST OREGON AND SOUTHWEST WASHINGTON. CONDITIONS
WILL BRIEFLY DRY OUT ON TUESDAY AS HIGH PRESSURE BUILDS. BY
WEDNESDAY MORNING, THE WEATHER PATTERN TURNS COOLER AND WETTER
AS A DEEPER SYSTEM APPROACHES FROM THE NORTHEAST PACIFIC. SNOW
LEVELS WILL FALL THURSDAY INTO FRIDAY, ALLOWING FOR ACCUMULATING
SNOW AT CASCADE PASSES. UNSETTLED WEATHER IS EXPECTED TO
CONTINUE THROUGH THE WEEKEND.
SHORT TERM...NOW THROUGH WEDNESDAY
A WEAK FRONT BRUSHING THE
AREA IS PRODUCING LIGHT PRECIPITATION MAINLY ALONG THE CASCADE
FOOTHILLS THIS AFTERNOON. ADDITIONAL MEASURABLE RAINFALL
THROUGH THIS EVENING REMAINS POSSIBLE, WITH THE GREATEST
LIKELIHOOD ACROSS SOUTHWEST WASHINGTON AND THE CASCADES, WHILE
LOWER CHANCES EXIST WEST OF THE MOUNTAINS. WINDS ARE LIGHT AND
VARIABLE THIS AFTERNOON, GENERALLY AROUND 5 MPH FROM THE SOUTH
TO SOUTHWEST, SHIFTING TO NORTHWESTERLY BY EVENING. ON TUESDAY,
A SHORTWAVE RIDGE BUILDS IN, PRODUCING SOME CLEARING AND DRIER
CONDITIONS IN THE MORNING. THIS TEMPORARY LULL GIVES WAY LATE
TUESDAY NIGHT AS A DEEP UPPER-LEVEL TROUGH APPROACHES FROM THE
NORTHEAST PACIFIC. A COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL
CROSS THE REGION ON WEDNESDAY AFTERNOON, BRINGING WIDESPREAD
RAIN. THE HEAVIEST PRECIPITATION IS EXPECTED ALONG THE COAST AND
COAST RANGE, WITH MORE MODERATE TOTALS IN THE INTERIOR VALLEYS.
PROBABILISTICALLY FOR 1 INCH OR MORE OF RAINFALL FROM 4 PM
WEDNESDAY TO 4 PM THURSDAY, THERE IS A 15-30% CHANCE WITHIN THE
INTERIOR VALLEY AND A 50-70% ALONG THE COAST AND COAST RANGE.
SNOW IS ALSO POSSIBLE IN THE CASCADES WEDNESDAY INTO THURSDAY,
THOUGH AMOUNTS REMAIN UNCERTAIN.
LONG TERM...THURSDAY THROUGH SUNDAY
SNOW LEVELS ARE EXPECTED
TO FALL WEDNESDAY NIGHT INTO THURSDAY MORNING, THOUGH MODEL
GUIDANCE REMAINS INCONSISTENT, RANGING FROM AS HIGH AS 8,000
FEET TO AS LOW AS 3,500 FEET. THIS UNCERTAINTY TRANSLATES TO LOW
CONFIDENCE IN SPECIFIC ACCUMULATION AMOUNTS. CURRENT GUIDANCE
SUGGESTS THAT BETWEEN WEDNESDAY AFTERNOON AND THURSDAY
AFTERNOON, THERE IS A 30-50% PROBABILITY THAT SNOW TOTALS COULD
REACH 1 INCH OR MORE AND A 10-20% PROBABILITY THAT SNOW TOTALS
COULD REACH SIX INCHES OR MORE, CLEARLY REFLECTING THE
UNCERTAINTY IN SNOW LEVELS AND TIMING. ADDITIONALLY, WHILE THE
TRACK OF THE LOW PRESSURE SYSTEM REMAINS UNCERTAIN, IT IS
POSSIBLE TO SEE GUSTY WINDS ON THURSDAY. FOR CHANCES OF WIND
GUSTS ABOVE 35 MPH ON THURSDAY, THERE IS A 15-30% CHANCE INLAND
AND 30-50% CHANCE ALONG THE COAST. THE COAST COULD EVEN SEE
ISOLATED WIND GUSTS UP TO 45 MPH AS GUIDANCE SUGGESTS A 10-20%
CHANCE OF SUCH WIND GUSTS TO OCCUR.
THE POST-FRONTAL AIR MASS ON THURSDAY WILL BE COOLER AND
SLIGHTLY UNSTABLE, SUPPORTING ISOLATED THUNDERSTORM ACTIVITY
MAINLY ALONG THE COAST, THOUGH OVERALL CHANCES HAVE DECREASED AS
CAPE VALUES ARE MARGINAL. ANY PASSING THUNDERSTORMS COULD
PRODUCE LIGHTNING, HEAVY DOWNPOURS, GUSTY OUTFLOW WINDS, AND
SMALL HAIL.
TEMPERATURES ALOFT ARE TRENDING SLIGHTLY WARMER THAN PREVIOUS
GUIDANCE, WITH 850 MB LEVELS DROPPING TO ROUGHLY 0-2°C THURSDAY
INTO FRIDAY, WHICH COULD PLACE SNOW LEVELS NEAR CASCADE PASSES,
BUT WITH MORE UNCERTAINTY COMPARED TO PREVIOUS GUIDANCE. FROM
THURSDAY MORNING INTO SATURDAY MORNING, SANTIAM AND WILLAMETTE
PASSES HAVE A 40-60% CHANCE OF SIX INCHES OR MORE OF SNOW, WHILE
AREAS NEAR GOVERNMENT CAMP HAVE SLIGHTLY LOWER PROBABILITIES.
A WARM FRONT LIFTING NORTH ON SATURDAY WILL RAISE SNOW LEVELS
ABOVE PASS ELEVATION, AND WET CONDITIONS ARE EXPECTED TO PERSIST
THROUGH THE WEEKEND AS ACTIVE WEATHER CONTINUES.
~12
AVIATION
A FRONT CONTINUES TO SLOWLY MOVE THROUGH NW OREGON AND
SW WASHINGTON AND IS STRETCHING FROM EASTERN SKAMANIA COUNTY TO
AROUND KONP AS OF 22Z MON. WEST OF THIS LINE, INLAND TERMINALS
HAVE IMPROVED TO VFR WHEREAS MVFR CONDITIONS FOR TERMINALS SOUTH
OF THE FRONT, INCLUDING KSLE AND KEUG. THESE TERMINALS MAY IMPROVE
TO VFR AFTER THE FRONTAL PASSAGE AFTER 23Z MON-01Z TUE. HOWEVER,
VFR CONDITIONS ARE ONLY EXPECTED TO BE BRIEF AS GUIDANCE INDICATES
POST-FRONTAL STRATUS COULD DEVELOP IN THE WILLAMETTE VALLEY
ANYWHERE BETWEEN 01-06Z TUE WITH A 60-80% CHANCE OF MVFR CEILINGS.
GUIDANCE SUGGESTS CONDITIONS WILL RETURN TO VFR BETWEEN 10-12Z
TUE IN THE NORTHERN WILLAMETTE VALLEY AS WINDS BECOME MORE
NORTHERLY. CONDITIONS COULD REMAIN LOWERED OR FLUCTUATE BETWEEN
VFR AND MVFR/IFR THROUGH 14-18Z TUE FOR THE CENTRAL WILLAMETTE
VALLEY, AND WILL LIKELY REMAIN LOWERED THROUGH 19-22Z IN THE
SOUTHERN WILLAMETTE VALLEY. ALONG THE COAST, MVFR CONDITIONS NORTH
OF KTMK ARE EXPECTED TO IMPROVE TO VFR BY 00-02Z TUE. FOR KTMK
AND SOUTH, MVFR/IFR ARE EXPECTED TO CONTINUE THROUGH AROUND 02-06Z
TUE BEFORE IMPROVING. VARIABLE WINDS LESS THAN 5 KTS WILL TURN
NORTHERLY BY 06Z TUE.
KPDX AND APPROACHES...VFR CONDITIONS ARE NOT EXPECTED TO LAST LONG
AS MVFR/IFR CEILINGS COULD RETURN AGAIN BY 00-03Z TUE. EASTERLY
WINDS LESS THAN 5 KT TODAY, TURNING MORE NORTHWESTERLY AFTER 00Z
TUE. -03
MARINE
BENIGN MARINE CONDITIONS CONTINUE THROUGH TUESDAY
NIGHT AS WEAK HIGH PRESSURE BUILDS OVER THE WATERS. WINDS WILL
REMAIN GENERALLY NORTHERLY WITH GUSTS LESS THAN 10 KTS. HIGH
CONFIDENCE (>95% CHANCE) THAT SEAS REMAIN BELOW 10 FT AT 10-12
SECONDS.
THE NEXT LOW PRESSURE SYSTEM IN THE NE PACIFIC WILL RETURN BREEZY
SOUTHERLY WINDS AND BUILDING SEAS WEDNESDAY INTO THURSDAY, WITH
HIGH CONFIDENCE FOR ANOTHER PERIOD OF CONDITIONS HAZARDOUS TO
SMALL CRAFT. AS THIS SYSTEM SWINGS A FRONT THROUGH THE WATERS,
THERE'S A 60-80% CHANCE OF FREQUENT SOUTHERLY WIND GUSTS
EXCEEDING 21 KT AND A GREATER THAN 90% CHANCE THAT SEAS BUILD
ABOVE 10 FT BY WEDNESDAY NIGHT. THERE IS ALSO A 40-60% CHANCE FOR
ISOLATED GALE- FORCE WIND GUSTS GREATER THAN 34 KT WEDNESDAY-
THURSDAY, WITH THE HIGHEST CHANCES ACROSS THE OUTER WATERS BEYOND
20-30 NM. ACTIVE WEATHER CONTINUES INTO THE END OF THE WEEK WITH
ADDITIONAL SYSTEMS MOVING THROUGH THE WATERS. -10/03
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
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