638
FXUS66 KPQR 131016
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
316 AM PDT TUE OCT 13 2026
SYNOPSIS
DRY WEATHER PREVAILS THROUGH THE WEEK. HIGH PRESSURE
STRENGTHENS THURSDAY AND FRIDAY, RESULTING IN MUCH WARMER
TEMPERATURES. OVER THE WEEKEND, COOLER TEMPERATURES AND CHANCES
FOR PRECIPITATION RETURN AS A TROUGH FROM THE GULF OF ALASKA
MOVES TOWARD THE PACIFIC NORTHWEST. CHANCES FOR WIDESPREAD
PRECIPITATION INCREASE FURTHER EARLY NEXT WEEK.
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
SATELLITE IMAGERY
AS OF EARLY TUESDAY MORNING SHOWS HIGH LEVEL CLOUDS MOVING INTO
NORTHWEST OREGON AND SOUTHWEST WASHINGTON AHEAD OF A SYSTEM
THAT'S MOVING INTO BRITISH COLUMBIA. CLEAR SKIES AND CALM WINDS
EARLIER THIS EVENING HAVE ALLOWED FOR EFFICIENT RADIATIONAL
COOLING; HOWEVER, THE INCREASING CLOUD COVER MAY LIMIT FURTHER
COOLING THIS MORNING. FOR NOW, FROST ADVISORIES REMAIN IN EFFECT
ACROSS MOST AREAS WEST OF THE CASCADES FOR LOW TEMPERATURES OF
33 TO 36 DEGREES RESULTING IN FROST DEVELOPMENT, AND A FREEZE
WARNING FOR THE UPPER HOOD RIVER VALLEY FOR SUB-FREEZING
TEMPERATURES OF 28 TO 32 DEGREES. ANYONE GROWING OUTDOOR
PLANTS THAT ARE SUSCEPTIBLE TO FROST DAMAGE SHOULD CONTINUE TO
COVER PLANTS OR LEAVE PLANTS INDOORS IF POSSIBLE. TEMPERATURES
WILL BE MONITORED OVER THE NEXT FEW HOURS, AND IF HIGH CLOUD
COVER PREVENTS TEMPERATURES FROM FALLING INTO THE LOW TO MID
30S, THE FROST ADVISORY AND/OR FREEZE WARNING MAY BE CANCELLED.
DRY CONDITIONS PREVAIL TODAY AND WEDNESDAY AS MUCH OF OUR AREA
REMAINS UNDER AN UPPER-LEVEL RIDGE. THIS RIDGE FLATTENS OUT A
BIT TODAY DUE TO THE SYSTEM MOVING INTO BRITISH COLUMBIA, BUT
PRECIPITATION IS GENERALLY EXPECTED TO REMAIN WELL-NORTH OF OUR
AREA. AN EXCEPTION WOULD BE THE SOUTH WASHINGTON COAST, WHERE
THERE IS A 15% CHANCE FOR LIGHT SHOWERS TONIGHT. THE THREAT FOR
FROST DECREASES TONIGHT AS INCREASING CLOUD COVER KEEPS
WEDNESDAY MORNING LOW TEMPERATURES SLIGHTLY WARMER THAN THE LAST
FEW NIGHTS. -10
LONG TERM...THURSDAY THROUGH MONDAY
ENSEMBLES REMAIN IN
AGREEMENT THAT UPPER-LEVEL RIDGING WILL AMPLIFY OVER THE PACIFIC
NORTHWEST THURSDAY AND FRIDAY, RESULTING IN TEMPERATURES
REBOUNDING TO THE MID TO UPPER 70S ACROSS INTERIOR VALLEYS AT
THE END OF THE WEEK. GUIDANCE ALSO SUGGESTS THAT THERMAL
TROUGHING WILL ALSO SET-UP OVER WESTERN OREGON, RETURNING
OFFSHORE EASTERLY FLOW ACROSS THE CASCADES AND COLUMBIA RIVER
GORGE BEGINNING WEDNESDAY NIGHT AND LASTING THROUGH FRIDAY
MORNING. WHILE THE GORGE REMAINS GUSTY THE ENTIRE TIME DUE TO
GAP-DRIVEN WINDS, OFFSHORE FLOW OVER THE CASCADES WILL FOLLOW A
DIURNAL PATTERN OF INCREASING WINDS OVERNIGHT AND WEAKENING IN
THE AFTERNOON. THE STRONGEST WINDS ARE EXPECTED ON THURSDAY,
WHERE THERE IS A 20-30% CHANCE FOR PEAK WIND GUSTS EXCEEDING 40
MPH THROUGH THE GORGE AT RIVER-LEVEL, AND A 20-40% CHANCE FOR
PEAK WIND GUSTS UP TO 50-55 MPH FOR EXPOSED RIDGETOPS WITHIN
HIGHER TERRAIN SURROUNDING THE GORGE (I.E. THREE CORNER ROCK).
OFFSHORE WINDS REMAIN WEAKER ACROSS THE CASCADES, WITH A 20-40%
CHANCE FOR PEAK WIND GUSTS EXCEEDING 30 MPH ALONG THE CREST AND
EXPOSED RIDGETOPS OF THE FOOTHILLS.
OVER THE WEEKEND, THE MAJORITY OF ENSEMBLE MEMBERS CONTINUE TO
FAVOR AN UPPER-LEVEL TROUGH MOVING SOUTHEASTWARD FROM THE GULF
OF ALASKA AND PUSHING THE RIDGE EASTWARD. WHILE THERE IS STILL
UNCERTAINTY WITH THE TIMING, STRENGTH, AND PLACEMENT OF THE
TROUGH, THERE IS HIGH CONFIDENCE THAT WE'LL SEE COOLER
TEMPERATURES AND INCREASING CHANCES FOR PRECIPITATION THIS
WEEKEND. CHANCES FOR AT LEAST 0.25 INCH OF LIQUID PRECIPITATION
FROM 5 AM SATURDAY TO 5 AM MONDAY ARE AROUND 30-45% ALONG THE
ALONG THE COAST, COAST RANGE, AND WILLAPA HILLS, AND 15-30%
ALONG THE I-5 CORRIDOR AND CASCADES. BY MONDAY, MOST ENSEMBLE
MEMBERS SUGGEST THAT THE TROUGH WILL ENTER THE PACIFIC
NORTHWEST, BRINGING INCREASED CHANCES FOR MORE WIDESPREAD
PRECIPITATION. -10
AVIATION...THROUGH 06Z WEDNESDAY
HIGH PRESSURE WILL MAINTAIN
VFR CONDITIONS WITH CLEAR SKIES THROUGH THE TAF PERIOD FOR MOST
LOCATIONS. THERE'S A 20-50% CHANCE OF LOCALIZED AREAS OF STRATUS
WITH MVFR/IFR CONDITIONS FORMING AGAIN AROUND 11-14Z TUE FOR
INLAND VALLEYS AND ALONG THE COAST WITH THE HIGHEST CHANCES IN THE
PORTLAND AREA. HAVE ADDED SOME SCT LOW CLOUDS ALONG WITH BCFG
TO SOME SITES THAT HAVE HAD ISSUES THE LAST COUPLE NIGHT. ANY
STRATUS OR FOG THAT DOES FORM SHOULD DISSIPATE AND IMPROVE TO VFR
BY 16-18Z TUE. HOWEVER, A WEAK FRONT BRUSHING THE PACNW WILL
BRING INCREASED HIGH LEVEL CLOUD COVER FROM THE NW AFTER 10-12Z
TUE. DEPENDING ON THE TIMING OF THESE CLOUDS, THIS COULD IMPACT
STRATUS DEVELOPMENT TUESDAY MORNING. LIGHT WINDS THROUGH THE
PERIOD.
KPDX AND APPROACHES...VFR CONDITIONS EXPECTED THROUGH THE PERIOD.
COULD SEE SOME STRATUS DEVELOP AROUND 13-15Z BUT CONFIDENCE IS LOW
BASED ON THE MODELS NOT HANDLING THIS PATTERN WELL. DECIDED TO ADD
A SCT005 DECK. WINDS REMAIN LIGHT AT LESS THAN 5 KT. -19/03
MARINE
BENIGN MARINE CONDITIONS EXPECTED THIS WEEK. TODAY AND
WEDNESDAY, LIGHT WINDS TURN MORE SOUTHERLY FROM A WEAK FRONT,
THEN RETURN NORTHERLY BY THE END OF THE WEEK. SEAS REMAIN AROUND
4-6 FT THIS WEEK WITH PERIODS OF 13-15 SECONDS THROUGH WEDNESDAY
AND 11-13 SECONDS LATE THIS WEEK. A STEEPER NORTHWESTERLY SWELL
ARRIVES THIS WEEKEND, BUILDING SEAS TO 7-9 FT BY SUNDAY AND 9-11
FT EARLY NEXT WEEK. THERE IS A 10-30% CHANCE FOR SEAS EXCEEDING 13
FT ON MONDAY, WITH THE HIGHEST CHANCES OVER THE WATERS BEYOND
30-40 NM. WILL ALSO NOTE THAT THE LONG PERIODS FROM THE SWELLS
THIS WEEK WILL RESULT IN A MODERATE SNEAKER WAVE THREAT. CAUTION
SHOULD BE USED WHEN IN OR NEAR THE WATER. -10
PQR WATCHES/WARNINGS/ADVISORIES
OR...FROST ADVISORY UNTIL 8 AM PDT THIS MORNING FOR ORZ102>109-
112>119-123>125.
FREEZE WARNING UNTIL 8 AM PDT THIS MORNING FOR ORZ121.
WA...FROST ADVISORY UNTIL 8 AM PDT THIS MORNING FOR WAZ202-204>208.
PZ...NONE.
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