766
FXUS66 KPQR 272238
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
338 PM PDT WED MAY 27 2026
SYNOPSIS
WARM TEMPERATURES INTO THURSDAY. SHOWER AND
THUNDERSTORM CHANCES OVER THE LANE COUNTY CASCADES THIS EVENING.
SHOWER AND THUNDERSTORM CHANCES SPREAD OVER THE NORTH OREGON AND
SOUTHERN WASHINGTON CASCADES THURSDAY AFTERNOON AND EVENING
WITH THE POTENTIAL FOR SOME THUNDERSTORMS TO BECOME SEVERE. NON-
SEVERE SHOWER AND THUNDERSTORM CHANCES WEST OF THE CASCADES
THURSDAY AFTERNOON AND EVENING. COOLER TEMPERATURES RETURN
FRIDAY, FOLLOWED BY A DRIER WEEKEND. WARMING TEMPERATURES RETURN
EARLY NEXT WEEK.
DISCUSSION...WEDNESDAY AFTERNOON THROUGH TUESDAY
WEAK HIGH
PRESSURE IS BUILDING OVER THE EASTERN PACIFIC OCEAN OFF OF THE
PACNW TODAY INTO THURSDAY AS THE PACNW SITS BETWEEN A LARGE
CLOSED LOW PRESSURE SYSTEM CENTERED OVER CALIFORNIA AND A
DEEPENING LOW PRESSURE SYSTEM SOUTH OF ALASKA. TEMPERATURES
TODAY AND THURSDAY WILL BE MUCH WARMER THAN PREVIOUS DAYS THIS
WEEK WITH THE INTERIOR LOWLANDS WARMING TO THE MID 70S TO LOW
80S EACH DAY. MORE IMPORTANTLY, THIS UPPER LEVEL PATTERN IS
PRODUCING SHOWER AND THUNDERSTORM CHANCES ACROSS THE REGION
TODAY AND THURSDAY AS MOISTURE WRAPS AROUND THE NORTH SIDE OF
THE CA LOW INTO CENTRAL OREGON TODAY AND SPREADS NORTH INTO
NORTHERN OREGON AND WASHINGTON TOMORROW. TODAY'S CHANCES REMAIN
LIMITED TO THE LANE COUNTY CASCADES WITH A 40-60% CHANCE OF
SHOWERS AND A 15-20% CHANCE OF THUNDERSTORMS.
CHANCES FOR SHOWERS AND THUNDERSTORMS BECOME MUCH MORE
WIDESPREAD AND INCREASE SIGNIFICANTLY ON THURSDAY. THE TROUGH
OVER THE NORTHEASTERN CASCADES DEEPENS CLOSER TO THE PACNW AS A
STRONG SHORTWAVES MOVES ALONG THE CA CLOSED LOW OVER OREGON,
LEADING TO STRONG CONVERGENCE AND LIFT. CAPE INCREASES
SIGNIFICANTLY BY MIDDAY/AFTERNOON TO 500-1000 J/KG IN THE LANE
COUNTY CASCADES AND 1200-1600 J/KG OVER THE REST OF THE NORTHERN
OREGON AND SOUTHERN WASHINGTON CASCADES AND HOOD RIVER COUNTY.
THIS IS A SIGNIFICANT AMOUNT OF CONVECTIVE POTENTIAL FOR THIS
AREA. ADDITIONALLY, MODELS SHOW 0-6 KM SHEAR OF 30-40 KTS
CONCURRENTLY. GUIDANCE DOES SHOW CAPE DECREASING FROM SOUTH TO
NORTH THROUGH THE AFTERNOON HOURS, LINGERING ABOVE 1000 J/KG THE
LONGEST IN HOOD RIVER AND SKAMANIA COUNTIES AND EAST INTO THE
EVENING HOURS, AND THIS AREA IS WHERE THUNDERSTORMS COULD BE
STRONGEST.
SPC INDICATES A MODERATE RISK (LEVEL 1 OUT OF 5) OF SEVERE
THUNDERSTORMS OVER THE NORTHERN OREGON AND SOUTHERN WASHINGTON
CASCADES AS WELL AS A SLIGHT RISK (LEVEL 2 OUT OF 5) OF SEVERE
THUNDERSTORMS OVER A PORTION OF HOOD RIVER COUNTY. WHAT THIS
MEANS IS THERE IS A 30-45% CHANCE OF THUNDERSTORMS WHERE SOME
THUNDERSTORMS MAY BECOME SEVERE WITH HAIL UP TO AT LEAST THE
SIZE OF A QUARTER (1 INCH) AND WIND GUSTS UP TO AT LEAST 60 MPH.
ADDITIONALLY, THERE'S A 15-25% CHANCE FOR NON-SEVERE
THUNDERSTORMS WEST OF THE CASCADES WITH BEST CHANCES GENERALLY
AROUND AND EAST OF INTERSTATE 5. THESE STRONG SHOWERS OR
THUNDERSTORMS COULD PRODUCE SMALL HAIL AND GUSTY WINDS LESS THEN
60 MPH. THUNDERSTORMS ARE EXPECTED TO FORM ALONG THE CASCADE
CREST IN THE AFTERNOON AND EVENING HOURS (EXCEPT LATE MORNING IN
THE LANE COUNTY CASCADES) WITH BEST CHANCES FOR SEVERE
THUNDERSTORMS BETWEEN 4-10 PM PDT. SHOWERS AND THUNDERSTORMS
THAT FORM ALONG THE CASCADES COULD THEN MOVE WEST INTO THE
FOOTHILLS AND INTERIOR LOWLANDS WITH BEST CHANCES OF THIS ALSO
BETWEEN 4-10 PM PDT.
HEAVY RAIN AND FLOODING POTENTIAL IS INCREASINGLY BECOMING A
CONCERN FOR BOTH THE CASCADES AND THE INTERIOR LOWLANDS. REFS,
HREF, AND MODEL SOUNDINGS INDICATE PWAT VALUES OF 1.2-1.4
INCHES OVER THE INTERIOR LOWLANDS, WHICH IS EXTREMELY HIGH FOR
LATE MAY. THIS IS RIGHT AROUND THE CLIMATOLOGICAL MAXIMUM OF
1.24 INCHES FOR MAY 28 BASED ON SOUNDING ANALYSIS AT SALEM, OR.
PWAT VALUES DO DECREASE SOMEWHAT AS ELEVATION INCREASES IN THE
CASCADES, BUT VALUES ARE STILL AROUND 0.75-1 INCH WHICH IS STILL
VERY HIGH FOR THIS TIME OF YEAR. HREF AND REFS ARE INDICATING
RAIN RATES COULD REACH 0.25-0.5 INCH PER HOUR OVER THE CASCADES
AND WESTERN FOOTHILLS WITH A FEW OUTLYING MEMBERS SUGGESTING
RAIN RATES UP TO 0.8-1 INCH PER HOUR POSSIBLE. FOR THE LOWLANDS,
THIS GUIDANCE IS INDICATING RAIN RATES UP TO 0.25-0.3 INCH PER
HOUR ARE POSSIBLE, MAINLY NORTH OF SALEM. THESE RAIN RATES COULD
CREATE FLOODING ISSUES FOR URBAN AREAS, LOW LYING AREAS, AND ANY
OTHER FLOOD PRONE AREAS AS WELL AS LANDSLIDES IF THE HIGHER RAIN
RATES MATERIALIZE.
ON FRIDAY, THE CLOSED LOW OVER CALIFORNIA FINALLY BEGINS MOVING
EAST AS THE TROUGH CONTINUES TO DEEPEN OVER THE EASTERN PACIFIC.
SHOWER CHANCES CONTINUE ON FRIDAY MORNING, SHIFTING TO MAINLY
OVER THE CASCADES BY THE AFTERNOON. TEMPERATURES ALSO COOL BACK
INTO THE MID 60S FOR THE INTERIOR LOWLANDS FRIDAY AND SATURDAY
AS THE TROUGH MOVES OVER THE PACNW.
A SIGNIFICANT WARMING TREND IS THEN EXPECTED SUNDAY INTO
TUESDAY. INTERIOR LOWLAND TEMPERATURES WARM INTO THE 70S ON
SUNDAY, LOW TO MID 80S ON MONDAY, AND UPPER 80S TO POSSIBLY
AROUND 90 DEGREES ON TUESDAY. NBM INDICATES A 20-50% CHANCE OF
HIGH TEMPERATURES EXCEEDING 90 DEGREES ON MONDAY FOR LOCATIONS
AROUND AND NORTH OF SALEM AND A 50-70% CHANCE ON TUESDAY FOR
LOCATIONS AROUND AND NORTH OF CORVALLIS. THIS PUSHES THESE AREAS
INTO MODERATE HEAT RISK WITH A 10-25% CHANCE OF MAJOR HEAT RISK
ON TUESDAY. -03
AVIATION
NORTHEAST FLOW ALOFT TODAY AS AN UPPER LEVEL LOW
SPINS OVER CENTRAL CALIFORNIA. EXPECT PREDOMINATELY VFR CONDITIONS
INLAND AS RESIDUAL STRATUS CONTINUES TO SCATTER OUT THIS MORNING.
STORMS OVER EASTERN AND CENTRAL OREGON WILL LIKELY SEND INCREASING
MID TO HIGH LEVEL CLOUDS ACROSS THE FORECAST AREA LATER TONIGHT.
LOW-END MVFR MARINE STRATUS ALONG THE COAST IS HAS PUSHED OFFSHORE
NEAR KAST, BUT REMAINS ALONG THE COAST NEAR KONP. THERE REMAINS
AROUND A 50% CHANCE OF IMPROVING TO VFR THIS AFTERNOON ALONG THE
CENTRAL OREGON COAST. CHANCES FOR MVFR TO IFR STRATUS RETURNING
TO THE COAST INCREASES TO AROUND 50-60% BY 05-07Z THURSDAY. NORTH
TO NORTHWESTERLY SURFACE WINDS INCREASE THIS AFTERNOON WITH GUSTS
UP TO 20-25 KT.
KPDX AND APPROACHES...VFR CONDITIONS WITH FEW HIGH CLOUDS EXPECTED
THROUGH TONIGHT. CHANCES FOR MVFR STRATUS RETURN TO AROUND 20-30%
BETWEEN 14-18Z THU. NORTHWEST WINDS EXPECTED TO INCREASE TO AROUND
10-12 KT WITH GUSTS UP TO 20 KT LATER THIS AFTERNOON. /DH
MARINE
HIGH PRESSURE OFFSHORE WILL MAINTAIN BREEZY NORTH TO
NORTHWESTERLY WINDS ACROSS THE COASTAL WATERS THROUGH THE
REMAINDER OF THE WEEK. THE STRONGEST WIND GUSTS ARE EXPECTED TO
PEAK LATER TODAY THROUGH THIS EVENING WITH GUSTS UP TO 25-30 KT,
HIGHEST ACROSS THE OUTER WATERS SOUTH OF CAPE FOULWEATHER.
OTHERWISE, EXPECT FREQUENT GUSTS TO AROUND 20 KT. SEAS AROUND 9 TO
10 FT THIS AFTERNOON REMAIN RELATIVELY STEEP AND CHOPPY, BEFORE
BUILDING TO AROUND 11 TO 12 FT LATER TONIGHT INTO THURSDAY AS A
MID TO LONG PERIOD NORTHWEST SWELL PUSHES THROUGH THE WATERS. WAVE
HEIGHTS THEN GRADUALLY SUBSIDE BACK DOWN TO AROUND 9 TO 10 FT BY
FRIDAY MORNING. THEREFORE, HAVE EXTENDED THE SMALL CRAFT ADVISORY
FOR ALL COASTAL WATERS, INCLUDING THE COLUMBIA RIVER BAR, THROUGH
THURSDAY NIGHT. HIGH PRESSURE IS EXPECTED TO STRENGTHEN THIS
WEEKEND ACROSS THE COASTAL WATERS LEADING TO A RETURN OF BREEZY
NORTHERLY WINDS. /DH
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT FRIDAY FOR PZZ210-251>253-
271>273.
WWW.WEATHER.GOV/PORTLAND
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