374
FXUS66 KPQR 291710 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
1010 AM PDT WED OCT 29 2025
UPDATED AVIATION, AND MARINE DISCUSSIONS, AND HAZARDS.
SYNOPSIS
LINGERING CLOUDS THIS MORNING AS THE FRONT PUSHES
EAST OF THE CASCADES, GIVING WAY TO MOSTLY SUNNY SKIES BY THE
AFTERNOON. DRY CONDITIONS AND SEASONABLE TEMPERATURES PERSIST
THROUGH AT LEAST THURSDAY. THE NEXT FRONTAL SYSTEM WILL BRING
ANOTHER ROUND OF WET AND BREEZY CONDITIONS FOR THE PACIFIC
NORTHWEST LATER FRIDAY INTO SATURDAY. HOWEVER, UNCERTAINTY
REMAINS FOR THE PRECIPITATION TIMING AND AMOUNTS WITH THIS
SYSTEM. SNOW LEVELS ARE EXPECTED TO REMAIN ELEVATED WELL ABOVE
8,000 FT THROUGH SATURDAY.
DISCUSSION...TODAY THROUGH TUESDAY
A QUICK HITTING FRONTAL SYSTEM
DROPPED ANYWHERE FROM A TENTH TO JUST OVER A HALF INCH OF RAIN
OVERNIGHT. HIGH PRESSURE BUILDS BACK OVER THE REGION TODAY, AS
LINGERING CLOUDS THIS MORNING GIVES WAY TO MOSTLY SUNNY SKIES BY
THIS AFTERNOON. EXPECT DRY CONDITIONS AND SEASONABLE TEMPERATURES,
WITH HIGHS IN THE UPPER 50S TO LOWER 60S THROUGH THURSDAY. CLEAR
SKIES TONIGHT WILL ALSO ALLOW FOR TEMPERATURES TO COOL, WITH
POTENTIAL FOR FROST FORMATION OR FOG TO DEVELOP OVERNIGHT INTO EARLY
THURSDAY FOR RURAL AREAS IN THE VALLEYS. WINDS ALSO TURN OFFSHORE
TONIGHT INTO THURSDAY, WITH BREEZY EASTERLY WINDS THROUGH THE
WESTERN COLUMBIA RIVER GORGE. GUSTS TO AROUND 30 MPH LIKELY FOR
PORTIONS OF THE EAST PORTLAND METRO AS THE TTD-DLS PRESSURE GRADIENT
INCREASES TO AROUND -5 TO -7 MB. ALSO EXPECT INCREASING CLOUDS ON
THURSDAY AS A WEAK SHORTWAVE TROUGH FLATTENS THE UPPER LEVEL
RIDGING.
ENSEMBLE GUIDANCE CONTINUES TO INDICATE THE NEXT WEATHER SYSTEM WILL
IMPACT THE REGION FRIDAY THROUGH SATURDAY. BUT GUIDANCE HAS ALSO
BEEN TRENDING TOWARD LESSER IMPACTS, AS PROBABILITIES ARE INCREASING
FOR THE SYSTEM TO REMAIN MORE TO THE NORTH ON FRIDAY. THIS FRONTAL
SYSTEM WILL BE ASSOCIATED WITH A STRONG LOW PRESSURE SYSTEM IN THE
GULF OF ALASKA AND LONGWAVE TROUGHING. LOOKING AT ONLY INTEGRATED
WATER VAPOR TRANSPORT (IVT) VALUES, THIS SYSTEM IS CLASSIFIED AS AN
ATMOSPHERIC RIVER WITH IVT VALUES ALONG THE NORTHERN OREGON COAST
EXPECTED TO PEAK BETWEEN AROUND 750 KG/M/S. HOWEVER, THE UPPER
TROUGH AND FRONTAL SYSTEM ASSOCIATED WITH THIS AR ARE MUCH WEAKER,
AS IS THE IVT CONVERGENCE, MEANING IMPACTS ARE LIKELY TO BE MINIMAL.
THE LATEST DETERMINISTIC FORECAST INDICATES AROUND 0.5-0.8 INCH OF
RAIN IN THE WILLAMETTE VALLEY, 0.8-1.0 INCH IN THE SW WASHINGTON
LOWLANDS, 1.0-2.0 INCHES FOR THE COAST AND COAST RANGE, AND 0.5-2.5
INCHES FOR THE CASCADES (HIGHEST IN THE NORTH) FROM 5 AM FRIDAY TO 4
AM SUNDAY. HOWEVER, QUITE A BIT OF UNCERTAINTY STILL EXISTS IN THE
EXACT TRACK OF WHERE AND WHEN THE FRONTAL SYSTEM AND MAIN IVT PLUME
WILL MAKE LANDFALL ON FRIDAY, AND ALSO HOW LONG THESE WILL IMPACT
THE REGION. NBM'S 90TH PERCENTILE (10% CHANCE OF EXCEEDING)
INDICATES 1.0-2.5 INCHES OF RAIN FOR INLAND VALLEYS AND 2.0-4.0
INCHES ALONG THE COAST AND TERRAIN FOR THE SAME 48 HOUR TIME PERIOD.
THE 10TH PERCENTILE (90% CHANCE OF EXCEEDING) INDICATES 0.15-0.75
INCHES OF RAIN FOR INLAND VALLEYS AND 0.25-1.25 INCHES ALONG THE
COAST AND TERRAIN. THE LREF, WHICH INCLUDES THE GEFS, EPS, AND GEPS,
SHOWS THE EARLIEST RAIN START TIME POSSIBLE AS EARLY FRIDAY MORNING
ALONG THE COAST AND AROUND NOON FRIDAY FOR THE WILLAMETTE VALLEY. ON
THE OTHER HAND, THE MEAN START TIME IS ANYWHERE FROM 5 PM (LONG
BEACH, WA) FRIDAY TO 8 AM SATURDAY (FLORENCE) ALONG THE COAST AND 12
AM (LONGVIEW, WA) TO 1 PM (EUGENE) SATURDAY FOR THE WILLAMETTE
VALLEY. THE FINAL PRECIPITATION AMOUNTS AND WHETHER THEY WILL REMAIN
SIMILAR TO THE CURRENT FORECAST OR EDGE MORE TOWARDS THE 90TH
PERCENTILE WILL REALLY DEPEND ON WHEN THE RAIN STARTS, HOW LONG IT
LASTS, AND WHERE THE STRONGEST IVT VALUES SET UP.
WINDS WILL ALSO BE BREEZY WITH THIS WEATHER SYSTEM, THOUGH NOT
NEARLY AS STRONG AS THIS PAST SATURDAY'S SYSTEM. THE MAJORITY OF
ENSEMBLE MEANS INDICATE WINDS ALONG THE COAST WILL PEAK AROUND 30-35
MPH SOMETIME LATE FRIDAY INTO SATURDAY, WITH A PEAK OF AROUND 20-30
MPH INLAND. NBM INDICATES A 20-30% CHANCE OF MAX WIND GUSTS
EXCEEDING 45 MPH ALONG THE COAST AND LESS THAN 5% INLAND.
SHOWERY CONDITIONS LINGER INTO SUNDAY. HIGHER CHANCES OF RAIN RETURN
LATER MONDAY INTO TUESDAY. SNOW LEVELS DROP BRIEFLY ON SUNDAY TO
AROUND 4500-5500 FEET NORTH OF LINN COUNTY, BUT AS PRECIPITATION IS
EXPECTED TO BE MINIMAL, LITTLE TO NO SNOW IS EXPECTED.
AVIATION
CLEARING SKIES OVERNIGHT ALLOWED FOR SIGNIFICANT
COOLING AND THEN DENSE FOG HAS FORMED THROUGHOUT THE AREA
STRETCHING FROM KKLS TO KEUG. THIS FOG HAS REDUCED MOST RUNWAYS TO
LIFR EXCEPT PATCHY AREAS OF SLIGHTLY CLEARER VISIBILITY. WIND AND
DAYTIME HEATING ARE GOING TO BE THE FACTOR TO HELP SCATTER OUT
THE FOG THIS MORNING. BASED ON CLIMATOLOGY IT IS COMMON TO HAVE IT
SCATTER AROUND 18Z. HOWEVER, GIVEN THE NORTHERLY FLOW IN AND
AROUND KEUG, THAT TERMINAL MAY HOLD ONTO THE FOG SLIGHTLY LONGER.
LOOKING AT SATELLITE IMAGERY, MOST OF THE FOG APPEARS TO BE
CONCENTRATED IN THE NORTHERN WILLAMETTE VALLEY AND CO-LOCATED
AREAS OF SOUTHWEST WASHINGTON.
THROUGH THE DAY, WEAK RIDGING WILL KEEP SKIES VFR AND EASTERLY
WINDS WILL BUILD ALOFT. SOME MODELS ARE SUGGESTING THAT ABOVE
1000 FT AFTER 06Z THU, WINDS AS HIGH AS 20 KT WILL BE OBSERVED AND
BY 12Z THU WINDS COULD REACH AS HIGH AS 35 KT BETWEEN 1000-2000
FT AGL. BUT, OTHER MODELS ARE SHOWING SIGNIFICANTLY LESS WIND.
GIVEN THIS UNCERTAINTY, HAVE DECIDED AGAINST ADDING ANY LLWS TO
THE TAFS, BUT CANNOT RULE OUT THE PROBABILITY. WILL CONTINUE TO
MONITOR AS THE DAY GOES ON WITH NEWER RUNS.
WITH CLEAR SKIES OVERNIGHT, THE INLAND VALLEYS WILL HAVE ANOTHER
CHANCE FOR FOG REDEVELOPMENT. RIGHT NOW THERE IS LESS THAN A 10%
CHANCE OF FOG IN THE NORTHERN WILLAMETTE VALLEY AND AROUND A 20%
CHANCE IN THE SOUTHERN WILLAMETTE VALLEY. OVERNIGHT STRATUS
DEVELOPMENT WILL BE THE LIMITING FACTOR.
KPDX AND APPROACHES...LIFR CONDITIONS FOR AT LEAST THE NEXT HOUR
BUT MAY SEE IT SLIGHTLY LONGER ON THE WESTERN SIDE OF THE
TERMINAL. AREA WEB CAMERAS ARE SHOWING SOME PARTIAL CLEARING BUT
NOT WIDESPREAD AT THIS TIME. THROUGH THE DAY WILL SEE FOG
DISSIPATE FROM EAST TO WEST AS WINDS INCREASE. WINDS WILL INCREASE
BECOMING NORTHERLY 4-6 KT IN THE AFTERNOON. OVERNIGHT, FOG IS
LIKELY TO REDEVELOP AFTER 09Z THU BUT IF WIND CONTINUES, COULD SEE
IT MUCH MORE PATCHY THAN THIS MORNING. WINDS ALOFT TOO WILL
AMPLIFY WITH AROUND A 30% CHANCE OF WINDS AS HIGH AS 20 KT.
-27
MARINE
UPDATE: SEAS HAVE INCREASED TO AROUND 5 FT ABOVE
FORECAST AT BUOY 46029 AND 46248. HAVE INCREASED SEAS TO AROUND 22
FT AT 14-16 SECONDS THROUGH EARLY THIS AFTERNOON. SEAS ARE RUNNING
AT AROUND THE 95TH PERCENTILE AT THIS POINT. PREVIOUS DISCUSSION
FOLLOWS. -27
HIGH PRESSURE BUILDS OVER THE WATERS TODAY. WESTERLY WINDS EASE
TO AROUND AROUND 10 KT OR LESS THIS MORNING THEN BECOME NORTHERLY
BY THIS AFTERNOON. PRESSURE GRADIENTS WILL INCREASE LATER TODAY AS
AN INVERTED TROUGH OF LOW PRESSURE DEVELOPS ALONG THE SOUTHERN
OREGON COAST. NORTHERLIES WITH GUSTS UP TO 25 KT ARE LIKELY BY
THIS EVENING, ESPECIALLY ACROSS THE OUTER COASTAL WATERS. TODAY
WILL ALSO FEATURE A MID-PERIOD WESTERLY SWELL THAT WILL MOVE
THROUGH THE WATERS AND QUICKLY BUILD SEAS TO AROUND 14 TO 17 FT
LATER THIS MORNING. WILL MAINTAIN THE HAZARDOUS SEAS WARNING FOR
THE COASTAL WATERS NORTH OF CAPE FOULWEATHER 8 PM PDT THIS
EVENING. ELSEWHERE, SMALL CRAFT ADVISORIES ARE IN EFFECT THROUGH
LATE TONIGHT. SEAS ARE EXPECTED TO GRADUALLY SUBSIDE THROUGH
THURSDAY, FALLING BELOW 10 FT BY THU AFTERNOON. ACTIVE WEATHER
RETURNS ON FRIDAY AS A FRONTAL SYSTEM APPROACHES THE WATERS.
SOUTHERLY WINDS ARE EXPECTED TO INCREASE THROUGH THE DAY WITH
GUSTS UP TO 25-30 KT LIKELY, WHILE THERE REMAINS AROUND A 50%
CHANCE FOR GALE FORCE WIND GUSTS ACROSS THE NORTHERN COASTAL
WATERS FRIDAY NIGHT. SEAS ARE ALSO EXPECTED TO BUILD INTO THE
WEEKEND, AS ANOTHER WESTERLY SWELL PUSHES IN BEHIND THE FRONT ON
SATURDAY. SIGNIFICANT WAVE HEIGHTS ARE LIKELY TO BUILD INTO THE
MID TEENS BY EARLY SATURDAY, WHILE THE PROBABILITY FOR SEAS
REACHING 20 FT HAVE DECREASED TO BELOW 10%.
PQR WATCHES/WARNINGS/ADVISORIES
OR...DENSE FOG ADVISORY UNTIL 11 AM PDT THIS MORNING FOR ORZ108-109-
111>118.
WA...DENSE FOG ADVISORY UNTIL 11 AM PDT THIS MORNING FOR WAZ204>207.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT THURSDAY FOR PZZ210-253-
273.
HAZARDOUS SEAS WARNING UNTIL 8 PM PDT THIS EVENING FOR PZZ251-
252-271-272.
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