106
FXUS66 KPQR 191739
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1039 AM PDT WED AUG 19 2026
UPDATED AVIATION DISCUSSION.
SYNOPSIS
WARM AND DRY CONDITIONS THROUGH THURSDAY. LOW
PRESSURE WILL RETURN COOLER TEMPERATURES AND CHANCES FOR SHOWERS
FRIDAY INTO SATURDAY, WITH A 5-10% CHANCE FOR THUNDERSTORMS.
WINDS OUT OF THE NORTH/NORTHWEST THROUGH THURSDAY, SHIFTING TO
THE WEST/SOUTHWEST ON FRIDAY. SEASONABLE WEATHER CONTINUES
SUNDAY INTO EARLY NEXT WEEK.
DISCUSSION...TODAY THROUGH TUESDAY
DRY AND WARM WEATHER
CONTINUES TODAY AND TOMORROW AS AN UPPER-LEVEL RIDGE AMPLIFIES
OVER THE ROCKIES AND GREAT BASIN. EXPECT HIGH TEMPERATURES NEAR
OR SLIGHTLY ABOVE AVERAGE FOR THIS TIME OF YEAR, WITH MID 80S
THIS AFTERNOON ACROSS INLAND VALLEYS AND 60S ALONG THE COAST.
HIGHS FOR INLAND VALLEYS INCREASE SLIGHTLY INTO THE UPPER 80S AS
THE UPPER RIDGE REACHES ITS PEAK STRENGTH. ONSHORE FLOW
CONTINUES AS BROAD UPPER-LEVEL TROUGHING SITS OVER THE NORTHEAST
PACIFIC WITH LIGHT WINDS FROM THE NORTH/NORTHWEST.
ON FRIDAY, THE AFOREMENTIONED TROUGH OVER THE NORTHEAST PACIFIC
WILL PROGRESS TOWARD THE PACIFIC NORTHWEST, BRINGING SLIGHTLY
COOLER TEMPERATURES, INCREASED CLOUD COVER, AND A 20-30% CHANCE
FOR SHOWERS IN THE AFTERNOON AND EVENING. WILL NOTE THAT THIS
UPPER-LEVEL PATTERN ON FRIDAY LOOKS LIKE A TYPICAL SET-UP FOR
THUNDERSTORM CHANCES, AT LEAST OVER THE CASCADES. SOUTHERLY FLOW
ALOFT WILL BRING INCREASED MOISTURE AND INSTABILITY INTO THE
MID-LEVELS OF THE ATMOSPHERE (5-10 KFT). VORTICITY FROM THE
UPPER-LEVEL TROUGH WILL ALSO PROVIDE THE NECESSARY FORCING FOR
CONVECTION. CURRENTLY, NBM GUIDANCE SHOWS LOW CHANCES (5-10%)
FOR THUNDERSTORMS ON FRIDAY, HOWEVER, IN THE PAST WE'VE SEEN
MODELS STRUGGLE WITH CAPTURING THE POTENTIAL FOR HIGH-BASED
THUNDERSTORMS. THERE IS ALSO UNCERTAINTY AMONG
DETERMINISTIC/ENSEMBLE GUIDANCE WITH HOW MUCH INSTABILITY
(SBCAPE/MUCAPE) THERE WILL BE, HOWEVER, WE WILL CONTINUE TO
EVALUATE THE THUNDERSTORM THREAT TODAY. THOSE WITH OUTDOOR PLANS
ON FRIDAY SHOULD MONITOR THE FORECAST CLOSELY THESE NEXT COUPLE
DAYS.
BY SATURDAY, ENSEMBLE GUIDANCE SHOWS THE UPPER-LEVEL TROUGH
MOVING INTO THE PACIFIC NORTHWEST WITH CHANCES FOR SHOWERS
CONTINUING THROUGH THE MORNING. AS THE ASSOCIATED SURFACE FRONT
MOVES THROUGH, WILL SEE WINDS SHIFT AND COME OUT OF THE
WEST/SOUTHWEST. THE STRONGEST WINDS ARE EXPECTED THROUGH THE
CENTRAL COLUMBIA RIVER GORGE AND HOOD RIVER VALLEY WHERE WINDS
COULD GUST TO 25-35 MPH. THERE IS ALSO A 30-60% CHANCE FOR AT
LEAST ISOLATED GUSTS EXCEEDING 40 MPH FOR THESE AREAS,
ESPECIALLY FOR HIGHER TERRAIN AND EXPOSED RIDGETOPS.
LATE THIS WEEKEND INTO EARLY NEXT WEEK, THE TROUGH WEAKENS AND
MOST ENSEMBLE MEMBERS SUGGEST A RETURN OF ZONAL FLOW BEFORE
ANOTHER UPPER-LEVEL TROUGH DROPS DOWN FROM THE GULF OF ALASKA
AND APPROACHES BRITISH COLUMBIA. AT THIS POINT, THERE STILL
REMAINS HIGH UNCERTAINTY WITH THE EXACT MAGNITUDE AND PLACEMENT
OF THE TROUGH NEXT WEEK. HOWEVER, THIS WOULD SUGGEST THAT
ONSHORE FLOW CONTINUES ACROSS THE REGION RESULTING IN SEASONABLE
TEMPERATURES FOR LATE AUGUST. -10
AVIATION...THROUGH 18Z THURSDAY
PREDOMINATELY VFR CONDITIONS
BEING OBSERVED AS OF 1730Z WED. STRATUS INLAND AND ALONG THE
COAST IS DISSIPATING QUICKLY WITH ANY DETERIORATED CIGS IMPROVING
TO VFR BY 18-20Z. ALONG THE COAST, IFR/MVFR STRATUS RETURNS BY
00-04Z THU. THERE'S A 20-40% CHANCE OF A RETURN OF MVFR/IFR CIGS
DUE TO MARINE STRATUS PUSHING INLAND ALONG THE LOWER COLUMBIA
RIVER TO PORTLAND AREA TERMINALS BETWEEN 12-15Z THU, IMPROVING TO
VFR BY 18Z. THERE'S LOWER CHANCES OF STRATUS PUSHING SOUTH OF
PORTLAND. LIGHT WEST/NORTHWEST WINDS AROUND 5-10 KT ALONG THE
COAST AND 4-7 KT ACROSS THE VALLEY.
KPDX AND APPROACHES...VFR CONDITIONS PREVAIL THROUGH THE TAF
PERIOD WITH A 20-40% CHANCE OF MVFR/IFR CIGS DUE TO MARINE STRATUS
FORMING AGAIN BY 12-15Z THU. IF CIGS DO LOWER, EXPECT IMPROVEMENT
TO VFR BY 18Z THU. NORTHWEST WINDS 4-7 KT. -03
MARINE
HIGH PRESSURE WILL CONTINUE TO SUPPORT NORTHERLY
WINDS ACROSS THE WATERS THROUGH THURSDAY WITH GUSTS REMAINING
BELOW 20 KT. FRIDAY TO SATURDAY, WEAK LOW PRESSURE MOVING OVER
THE NORTHEAST PACIFIC WILL SHIFT WINDS OUT OF THE SOUTH TO
SOUTHWEST ACROSS THE WATERS. AS THE SURFACE FRONT MOVES THROUGH
SATURDAY MORNING, THERE WILL BE A 40-50% CHANCE FOR MAXIMUM WIND
GUSTS UP TO 25 KT FOR THE INNER WATERS NORTH OF CAPE FALCON,
INCLUDING THE COLUMBIA RIVER BAR. FOR THE REST OF THE WATERS,
CHANCES ARE AROUND 5-10%.
HIGH PRESSURE AND NORTHERLY WINDS RETURN BY SUNDAY WITH A 50-60%
CHANCE FOR NORTHERLY WIND GUSTS EXCEEDING 21 KTS IN THE AFTERNOON
AND EVENING HOURS SOUTH OF CAPE FOULWEATHER. SEAS OF 4-6 FT
PERSIST THROUGH THE PERIOD. PERIODS AROUND 12 SEC TODAY MAY RESULT
IN A MODERATE RISK FOR SNEAKER WAVES ALONG THE COAST. CAUTION
SHOULD BE USED WHEN IN OR NEAR THE WATER. -10
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
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