675
FXUS66 KPQR 131037
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
337 AM PDT SUN SEP 13 2026
SYNOPSIS
COOL AND UNSETTLED CONDITIONS CONTINUE TODAY AS AN
UPPER-LEVEL LOW MOVES EAST OF THE CASCADES. SHOWERS WILL
GRADUALLY BECOME MORE SCATTERED AND TERRAIN FOCUSED THROUGH THE
DAY, WITH LOWLAND AREAS TRENDING DRIER BY THIS AFTERNOON.
TEMPERATURES THEN BEGIN TO RECOVER MONDAY AND TUESDAY BEFORE A
MORE PRONOUNCED WARM-UP WEDNESDAY AND THURSDAY AS HIGH PRESSURE
BUILDS INTO THE PACIFIC NORTHWEST. INCREASING EASTERLY FLOW
MIDWEEK COULD BRING GUSTY WINDS TO THE COLUMBIA RIVER GORGE,
CASCADES AND ADJACENT FOOTHILLS, WHILE ALSO CONTRIBUTING TO
WARMER AND DRIER CONDITIONS.
DISCUSSION...NOW THROUGH SATURDAY
THE UPPER-LEVEL LOW IS
CROSSING THE CASCADES THIS MORNING, WITH SHOWERS CONTINUING
ACROSS THE REGION. ADDITIONAL RAINFALL TODAY WILL GENERALLY BE
LIGHT ACROSS THE LOWLANDS. IN NORTHWEST OREGON, EXPECT ANOTHER
0.01-0.15 INCH, WITH LOCALLY HIGHER AMOUNTS UP TO AROUND 0.25
INCH IN THE CASCADES. SOUTHWEST WASHINGTON SHOULD SEE SIMILAR
0.01-0.15 INCH ACROSS MOST LOCATIONS, WHILE THE WILLAPA HILLS
AND SOUTHWEST WASHINGTON CASCADES, INCLUDING THE FOOTHILLS,
COULD PICK UP ANOTHER 0.25-0.50 INCH.
AS THE LOW PULLS FARTHER EAST TODAY, SHOWERS WILL BECOME
INCREASINGLY SCATTERED AND FOCUSED OVER HIGHER TERRAIN. THE
INLAND VALLEYS AND IMMEDIATE COAST SHOULD TREND MOSTLY DRY BY
MID TO LATE AFTERNOON, WHILE THE CASCADES AND FOOTHILLS REMAIN
MORE FAVORABLE FOR LINGERING SHOWERS INTO THE EVENING. A FEW
AREAS COULD SEE OCCASIONAL MODERATE RAIN WITH THE MORE
PERSISTENT TERRAIN-FOCUSED SHOWERS, BUT WIDESPREAD STEADY
PRECIPITATION IS NOT EXPECTED.
THUNDERSTORM CHANCES ARE MINIMAL TODAY, WITH ONLY AROUND A 10%
CHANCE ACROSS THE CASCADES THIS AFTERNOON. COLD-CORE FUNNEL
CLOUDS REMAIN POSSIBLE WITH STRONGER SHOWERS, PARTICULARLY NEAR
THE CASCADES. THESE ARE GENERALLY SHORT-LIVED AND TYPICALLY
REMAIN ALOFT.
THE PATTERN BECOMES PROGRESSIVELY QUIETER MONDAY AND TUESDAY AS THE
UPPER LOW MOVES FARTHER EAST AND WEAK RIDGING BEGINS TO DEVELOP
OFFSHORE. A WEAK SHORTWAVE DROPPING SOUTH ALONG THE BRITISH
COLUMBIA COAST LATE MONDAY WILL MAINTAIN SOME NORTHWESTERLY FLOW
ACROSS THE REGION, BUT TEMPERATURES SHOULD CONTINUE TO RECOVER
FROM THE COOL WEEKEND. INTERIOR HIGHS SHOULD REACH THE LOW TO
MID 70S BY TUESDAY, WITH COASTAL LOCATIONS GENERALLY IN THE MID
60S.
A MORE SUBSTANTIAL WARM-UP ARRIVES WEDNESDAY AND THURSDAY AS THE
OFFSHORE RIDGE SHIFTS EASTWARD INTO THE PACIFIC NORTHWEST. ENSEMBLE
AND DETERMINISTIC GUIDANCE HAVE CONTINUED TO CONVERGE ON THIS
SOLUTION, SUPPORTING HIGHS WELL INTO THE 80S ACROSS THE INTERIOR
LOWLANDS. FOR THURSDAY AFTERNOON, THERE IS CURRENTLY A 15-40%
CHANCE OF TEMPERATURES REACHING 90 DEGREES OR HIGHER ACROSS
PARTS OF THE CENTRAL AND NORTHERN WILLAMETTE VALLEY, WITH
PROBABILITIES OF 0-10% ELSEWHERE.
EASTERLY FLOW IS ALSO BECOMING INCREASINGLY LIKELY WEDNESDAY INTO
THURSDAY AS THE RIDGE STRENGTHENS AND LOWER PRESSURE DEVELOPS OVER
NORTHERN CALIFORNIA. THE STRONGEST WINDS CURRENTLY APPEAR MOST
LIKELY WEDNESDAY INTO THURSDAY MORNING, WITH GUSTS OF 20-30 MPH
AND ISOLATED GUSTS NEAR 35 MPH POSSIBLE IN WIND-PRONE AREAS OF
THE COLUMBIA RIVER GORGE, CASCADES AND ADJACENT FOOTHILLS. THE
HIGHER TERRAIN OF THE COAST RANGE COULD ALSO BECOME BREEZY,
ALTHOUGH CONFIDENCE REMAINS LOWER THERE. AT THE HIGHER END OF
THE FORECAST ENVELOPE, THERE IS CURRENTLY A 10-15% CHANCE OF
GUSTS EXCEEDING 40 MPH IN THE MOST EXPOSED LOCATIONS NEAR AND
WITHIN THE COLUMBIA RIVER GORGE.
THE COMBINATION OF WARMER TEMPERATURES, LOWER HUMIDITY AND
INCREASING EASTERLY WINDS WEDNESDAY AND THURSDAY COULD PRODUCE A
PERIOD OF ELEVATED FIRE-WEATHER CONCERNS. THE EVOLUTION OF THE
MIDWEEK WIND AND TEMPERATURE PATTERN WILL CONTINUE TO BE MONITORED
AS CONFIDENCE INCREASES.
FRIDAY, TEMPERATURES BEGIN TO TREND COOLER AS THE RIDGE WEAKENS.
CHANCES OF HITTING 90 DEGREES LOWER FOR FRIDAY, WITH GUIDANCE
SUGGESTING A 15-30% CHANCE. WHILE GUIDANCE PROJECTS LARGE
TEMPERATURE SPREAD (INCREASED UNCERTAINTY) BY SATURDAY, THERE IS
MODERATE TO HIGH CONFIDENCE THAT TEMPERATURES WILL DROP BACK
DOWN TO THE 70S. ~12/99
AVIATION...THROUGH 12Z MONDAY
A LOW PRESSURE SYSTEM CONTINUES
TO PUSH EAST THROUGH THE CASCADES AS OF 11Z SUN. CURRENTLY,
THERE IS A MIX OF VFR/MVFR CONDITIONS THROUGHOUT THE AIRSPACE,
WITH MOSTLY MVFR CIGS ALONG THE COAST AND MOSTLY VFR INLAND.
CONFIDENCE OF CONDITIONS FOR INLAND TERMINALS REMAINS MODERATE
TO LOW AS CURRENT CONDITIONS HAVE BEEN BOUNCING AND RAIN
SHOWERS RETURNING TO THE AREA BRINGS A 20-40% CHANCE OF MVFR
CIGS UNTIL 21-24Z SUN. BEYOND 00Z MON, INLAND TERMINALS WILL
LIKELY REMAIN VFR THROUGH THE REST OF THE PERIOD AS GUIDANCE
ONLY SUGGESTS A 10-20% CHANCE OF MVFR CIGS. COASTAL TERMINALS
MAY REMAIN UNDER MVFR CIGS THROUGH THE PERIOD, WITH GUIDANCE
SUGGESTING A 40-80% CHANCE OF MVFR AND 15-30% CHANCE OF IFR CIGS
THROUGH 18Z SUN, THEN GRADUALLY DECREASING TO A 20-50% CHANCE OF
MVFR CIGS THROUGH THE REST OF THE PERIOD. OVERALL, BEST CHANCES
FOR VFR CONDITIONS WILL BE AFTER 00Z MON AS SHOWERS DISSIPATE.
OTHERWISE, EXPECT SOUTH TO SOUTHWESTERLY WINDS AROUND 5-10 KT
THROUGH THE PERIOD, WITH THE EXCEPTION OF 8-12 KT WITH GUSTS UP
TO 18 KT AT KAST DURING THE AFTERNOON.
KPDX AND APPROACHES...CURRENT VFR CONDITIONS MAY INFREQUENTLY
DROP TO MVFR DUE TO PASSING SHOWERS FROM NOW UNTIL 00Z MON.
CONFIDENCE OF CONDITIONS REMAIN LOW TO MODERATE AS GUIDANCE
SUGGESTS A 20-40% CHANCE OF MVFR CIGS THROUGH 00Z MON. RAIN
SHOWERS WILL DISSIPATE BY 00Z MON, ALLOWING FOR PREDOMINANTLY
VFR CONDITIONS. SOUTH WINDS AROUND 4-8 KT WILL SHIFT MORE
SOUTHWEST DURING THE AFTERNOON, THEN BACK TO SOUTH OVERNIGHT.
~12
MARINE
A WEAK SURFACE LOW CONTINUES TO MOVE EAST THROUGH THE INTERIOR
THIS MORNING, MAINTAINING SOME RAIN SHOWERS OVER THE WATERS,
PRIMARILY NORTH OF CAPE FOULWEATHER. ONSHORE FLOW AT 5-10 KT
OUT OF THE WEST TO SOUTHWEST WILL BUILD AS RAIN SHOWER COVERAGE
DECREASES THROUGH TODAY. A PERSISTENT NORTHWESTERLY SWELL AT
8-9 SECONDS WILL MAINTAIN OVERALL SEAS AROUND 5 FT THROUGH THE
WEEKEND.
SURFACE HIGH PRESSURE REBUILDS OVER THE WATERS THROUGH THE FIRST
HALF OF NEXT WEEK, WITH NORTHERLY FLOW RETURNING MONDAY
AFTERNOON/EVENING. STRENGTHENING NORTHERLIES THROUGH MIDWEEK
WILL SEE 50% OR GREATER CHANCES OF WINDS 20 KT OR HIGHER ON
TUESDAY, WEDNESDAY, AND THURSDAY. SEAS AROUND 5 FT WITH A
DOMINANT NORTHWESTERLY SWELL AT 8-9 SECONDS OTHERWISE CONTINUE,
ALTHOUGH MAY INCREASE TO AROUND 6-7 FT ON THURSDAY. ~12/36
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
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