782
FXUS66 KPQR 262218
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
318 PM PDT TUE MAY 26 2026
SYNOPSIS
SCATTERED SHOWERS CONTINUE THROUGH THIS EVENING AS
LOW PRESSURE REMAINS OVERHEAD. WARMER AND DRIER CONDITIONS
RETURN TOMORROW AS HIGH PRESSURE REBUILDS. WRAP-AROUND MOISTURE
WILL LEAD TO CHANCES FOR SHOWERS AND A 15-20% CHANCE FOR
THUNDERSTORMS ACROSS THE LANE COUNTY CASCADES WEDNESDAY
AFTERNOON. THURSDAY, INCREASING MOISTURE WILL LEAD TO MORE
WIDESPREAD CHANCES FOR SHOWERS ALONG THE I-5 CORRIDOR WITH
INCREASING CHANCES FOR THUNDERSTORMS ACROSS THE CASCADES.
COOLER TEMPERATURES RETURN FRIDAY WITH DRIER CONDITIONS THIS
WEEKEND. UNCERTAINTY WITH HOW WARM TEMPERATURES GET EARLY NEXT
WEEK.
DISCUSSION...TODAY THROUGH MONDAY
RADAR AND SATELLITE IMAGERY
AS OF EARLY TUESDAY AFTERNOON DEPICTS SCATTERED SHOWERS AND
CLOUDS AS A BROAD UPPER-LEVEL LOW MOVES OVERHEAD AND TRACKS
SOUTHWARD TOWARD CALIFORNIA AND NEVADA. WHILE MOST SHOWERS ARE
CURRENTLY OVER THE COAST RANGE AND CASCADES, CHANCES FOR SHOWERS
CONTINUE ACROSS NORTHWEST OREGON AND SOUTHWEST WASHINGTON
THROUGH THIS EVENING. OBSERVATIONS INDICATE LIMITED INSTABILITY;
THEREFORE, CHANCES FOR ISOLATED THUNDERSTORMS REMAIN LOW
(10-15%) THROUGH THIS EVENING. ANY PASSING THUNDERSTORMS THAT DO
FORM MAY PRODUCE LIGHTNING, BRIEF HEAVY DOWNPOURS, ERRATIC
WINDS, AND/OR SMALL HAIL.
TEMPERATURES REBOUND WEDNESDAY AND THURSDAY AS HIGH PRESSURE RE-
BUILDS OVER THE AREA AND THE AFOREMENTIONED LOW DROPS DOWN INTO
THE GREAT BASIN. HIGH TEMPERATURES ARE FORECAST 5-10 DEGREES
ABOVE NORMAL ACROSS INTERIOR VALLEYS FOR THIS TIME OF YEAR,
WARMEST FROM THE PORTLAND/VANCOUVER METRO NORTHWARD. CHANCES FOR
EXCEEDING 80 DEGREES ACROSS THE PORTLAND/VANCOUVER METRO ON
WEDNESDAY HAVE INCREASED TO 55-75%, AND 80-90% ON THURSDAY. THE
REST OF THE INTERIOR VALLEYS HAVE A 30-50% CHANCE FOR EXCEEDING
80 DEGREES ON WEDNESDAY AND THURSDAY. WHILE WEDNESDAY REMAINS
PREDOMINATELY DRY AND WARM, WILL NOTE THAT WRAP-AROUND MOISTURE
WILL RESULT IN A 30-50% CHANCE FOR SHOWERS AND A 10-20% CHANCE
FOR THUNDERSTORMS ACROSS THE LANE COUNTY CASCADES WEDNESDAY
EVENING. BY THURSDAY, INCREASING WRAP-AROUND MOISTURE WILL
RESULT IN MORE WIDESPREAD CHANCES FOR SHOWERS ACROSS THE
CASCADES AND INTO THE I-5 CORRIDOR. INCREASING INSTABILITY FROM
SOUTH-SOUTHEAST FLOW WILL ALSO SUPPORT A 20-40% CHANCE FOR
THUNDERSTORMS ACROSS THE CASCADES THURSDAY AFTERNOON/EVENING,
WITH THE HIGHEST CHANCES ACROSS THE LANE COUNTY CASCADES. IF
SHOWER OR THUNDERSTORM COVERAGE IS MORE WIDESPREAD THROUGHOUT
THE DAY ON THURSDAY, CLOUD COVER COULD RESULT IN SLIGHTLY COOLER
TEMPERATURES.
FRIDAY INTO THE WEEKEND, TEMPERATURES COOL DOWN AS ENSEMBLE
GUIDANCE SUGGESTS ANOTHER TROUGH MOVING IN FROM THE NORTHEAST
PACIFIC AND LOWERING 500 MB HEIGHTS. CHANCES FOR SHOWERS REMAIN
ON FRIDAY DUE TO LINGERING WRAP-AROUND MOISTURE FROM THE GREAT
BASIN LOW, HOWEVER, CONDITIONS DRY OUT OVER THE WEEKEND DUE TO
LIMITED MOISTURE DESPITE THE TROUGHING. UNCERTAINTY IN
TEMPERATURES DRASTICALLY INCREASE FOR EARLY NEXT WEEK, WITH
ENSEMBLE GUIDANCE SUGGESTING THE POSSIBILITY OF AN AFTERNOON
HIGH TEMPERATURE ANYWHERE BETWEEN 73 AND 93 DEGREES ON MONDAY
FOR KPDX (COOLEST AND WARMEST SCENARIOS). CURRENT GUIDANCE
SUGGESTS A 15-30% CHANCE FOR TEMPERATURES EXCEEDING 90 DEGREES
ACROSS THE GREATER PORTLAND/VANCOUVER METRO AREA ON MONDAY. FOR
THE REST OF THE WILLAMETTE VALLEY, SOUTHWEST WA LOWLANDS, AND
UPPER HOOD RIVER VALLEY, CHANCES FOR EXCEEDING 90 DEGREES REMAIN
AROUND 5-15%. THE WIDE RANGE OF TEMPERATURE VALUES COMES FROM
UNCERTAINTY WITH THE UPPER LEVEL PATTERN. THE MAJORITY OF
ENSEMBLE GUIDANCE ARE IN AGREEMENT WITH ABOVE-AVERAGE 500 MB
HEIGHTS ACROSS THE REGION ON MONDAY DUE TO POTENTIAL RIDGING;
HOWEVER, THERE IS UNCERTAINTY WITH THE EXACT PLACEMENT AND
MAGNITUDE OF RIDGING WHICH WOULD DETERMINE HOW WARM WE GET.
-10
AVIATION
MOSTLY VFR CONDITIONS ACROSS THE AIR SPACE INTO THE
EVENING HOURS. LIGHT SHOWERS REMAIN POSSIBLE MAINLY OVER THE
HIGHER TERRAIN AND IN THE SOUTHERN WILLAMETTE VALLEY INTO
TONIGHT. CHANCES AROUND TERMINALS ARE RELATIVELY LOW SO HAVE
KEPT OUT OF THE FORECAST AT THIS TIME. NORTH/NORTHWEST WINDS AT
8-14 KT WITH GUSTS TO AROUND 20 KT POSSIBLE THROUGH 04Z
WEDNESDAY.
MARINE STRATUS IS EXPECTED TO DEVELOP THIS EVENING, APPROACHING
THE COASTAL TERMINALS BETWEEN 02-06Z WEDNESDAY. SUB-VFR CIGS ARE
EXPECTED TO PERSIST THROUGH 16-18Z ALONG THE COAST. GUIDANCE
SUGGESTS STRATUS BUILDING INLAND TOWARD THE WILLAMETTE VALLEY
OFF THE CASCADE FOOTHILLS. MVFR CIGS ARE POSSIBLE AFTER 10Z,
MAINLY AROUND THE EASTERN METRO AND SOUTHERN WILLAMETTE VALLEY.
KPDX AND APPROACHES...MAINLY VFR CONDITIONS EXPECTED THROUGH THE
TAF PERIOD. NORTHERLY WINDS 8-12 KT WITH A FEW GUSTS TO AROUND
20 KT POSSIBLE THIS AFTERNOON. COULD SEE MVFR CIGS REDEVELOP
LATE TONIGHT AFTER 12-14Z WEDNESDAY. THERE IS A 20-50% CHANCE
OVER THE EASTERN METRO. -19
MARINE
WESTERLY SWELL CONTINUES TO MOVE THROUGH THE WATERS
BUT THE PEAK WAVE HEIGHTS SUBSIDED EARLIER THIS MORNING. SEAS
ARE GENERALLY BELOW 15 FT AND WILL CONTINUE TO DROP CLOSER TO 10
FT OVERNIGHT. WINDS FROM THE NORTHWEST AT AROUND 10 KT. SMALL
CRAFT ADVISORIES REMAIN IN EFFECT FOR ALL ZONES DUE TO STEEP
SEAS. THE COLUMBIA RIVER BAR WILL DROP OFF AT 11 PM TONIGHT AS
SEAS SUBSIDE. THE SMALL CRAFT FOR THE INNER WATERS HAS BEEN
EXTENDED TO 1 AM AS AND THE OUTER WATERS EXTENDED THROUGH 5 PM
WEDNESDAY FOR STEEP SEAS AND WIND GUSTS UP TO 25 KT. ANOTHER
NORTHWESTERLY SWELL IS EXPECTED TO MOVE INTO THE WATER ON
THURSDAY, STEEPENING SEAS ACROSS ALL MARINE ZONES AGAIN.
CONDITIONS ARE BORDERLINE FOR HAZARDOUS SEAS WARNING OR A SMALL
CRAFT ADVISORY AT THIS TIME. -19
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR PZZ210.
SMALL CRAFT ADVISORY UNTIL 2 AM PDT WEDNESDAY FOR PZZ251>253.
SMALL CRAFT ADVISORY UNTIL 5 PM PDT WEDNESDAY FOR PZZ271>273.
WWW.WEATHER.GOV/PORTLAND
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