890
FXUS66 KPQR 290530
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1030 PM PDT THU MAY 28 2026
.UPDATED AVIATION DISCUSSION.
SYNOPSIS
SHOWER AND THUNDERSTORM CHANCES CONTINUES THIS
AFTERNOON AND EVENING. STRONG TO SEVERE THUNDERSTORMS ARE
POSSIBLE OVER THE CASCADES AND HOOD RIVER COUNTY. THERE ARE
DECREASING CHANCES OF THUNDERSTORMS OVER THE VALLEY TONIGHT. AS
THUNDERSTORMS MOVE WEST OF THE CASCADES, THEY ARE LIKELY TO
WEAKEN INTO SHOWERS. SHOWERS CONTINUE INTO FRIDAY WITH COOLER
CONDITIONS INTO SATURDAY. DRY WEATHER WITH INCREASING
TEMPERATURES SUNDAY INTO EARLY NEXT WEEK.
DISCUSSION...THURSDAY AFTERNOON THROUGH WEDNESDAY
THE MAIN
FOCUS OF THE FORECAST IS THE CHANCE FOR SEVERE THUNDERSTORMS
OVER THE CASCADES TODAY WITH THE BEST CHANCES AROUND HOOD RIVER
COUNTY AND EAST OF THE CASCADES. THERE IS A SEVERE THUNDERSTORM
WATCH IN EFFECT FOR HOOD RIVER COUNTY UNTIL 8 PM TONIGHT, THOUGH
THUNDERSTORMS CHANCES CONTINUE THROUGH 10 PM TONIGHT.
THUNDERSTORM CHANCES HAVE DIMINISHED SIGNIFICANTLY OVER THE
VALLEY FOR THIS AFTERNOON AND EVENING WITH ONLY A 5-10% CHANCE
THAT STORMS MOVING OFF OF THE CASCADES HOLD TOGETHER.
NOW FOR THE DEEPER ANALYSIS. A LARGE UPPER CLOSED LOW PRESSURE
SYSTEM REMAINS CENTERED OVER CALIFORNIA WHILE AN UPPER TROUGH
DEEPENS IN THE NORTHEASTERN PACIFIC. THE PACNW REMAINS
SANDWICHED BETWEEN THE TWO IN AN AREA OF CONVERGENCE AS A
SHORTWAVE ALONG THE CA LOW IS MOVING NORTHWEST INTO THE REGION
TODAY. REFS AND HREF GUIDANCE ALONG WITH FORECAST SOUNDINGS
INDICATE CAPE VALUES COULD INCREASE TO 1200-1600 J/KG OVER THE
CASCADES, ESPECIALLY NORTH OF LANE COUNTY AND PEAKING AROUND
HOOD RIVER AND SKAMANIA COUNTIES. ADDITIONALLY, 0-6 KM SHEAR
VALUES ARE EXPECTED TO PEAK AROUND 35-40 KTS OVER THE CASCADES.
GUIDANCE INDICATES THE BEST CONDITIONS FOR SEVERE THUNDERSTORMS
WILL BE OVER HOOD RIVER COUNTY AND POSSIBLY INTO SOUTHERN
SKAMANIA COUNTY WHERE CAPE WILL BE HIGHEST. STRONG WIND GUSTS OF
60 MPH AND LARGE HAIL AROUND 1 INCH ARE POSSIBLE IN STRONGER
THUNDERSTORMS, AS WELL AS HEAVY RAIN.
SPC MESOANALYSIS AT 2 PM PDT INDICATES MUCAPE OVER 1000 J/KG
AND 0-6 KM SHEAR OVER 30 KTS WITH PWAT VALUES OVER 1 INCH OVER
THE CASCADES. ONE DIFFERENCE FROM PREVIOUS FORECASTS IS THE
LOCATION OF THE SHORTWAVE REMAINS JUST SLIGHTLY FARTHER EAST,
WHICH MEANS THE LIFT FOR THUNDERSTORMS OVER THE CASCADE CREST
AND WEST HAS MOVED LATER IN TIME COMPARED TO PREVIOUS FORECASTS.
INSTEAD OF INITIATING LATE THIS MORNING, WE ARE JUST NOW SEEING
INITIATION OVER THE SKAMANIA/YAKIMA COUNTY BORDER. BETTER
CONDITIONS FOR SEVERE THUNDERSTORMS ARE BEING OBSERVED OVER
EASTERN OREGON, AND MODELS INDICATE THAT THESE ISOLATED STORMS
FORMING OVER EASTERN OREGON WILL EVENTUALLY BECOME MORE LINEAR
THIS AFTERNOON AS THEY MOVE WEST THROUGH CENTRAL OREGON AND INTO
THE CASCADES. SINCE THIS IS NOW OCCURRING LATER IN THE DAY, THE
CONVECTIVE POTENTIAL WILL BE WANING AS SURFACE HEATING COOLS.
THIS WILL LIKELY PREVENT THUNDERSTORMS FROM BEING ABLE TO HOLD
TOGETHER AS THEY MOVE WEST OF THE CREST. COULD STILL SEE
THUNDERSTORMS IN THE WESTERN FOOTHILLS, BUT THEY LIKELY WILL
WEAKEN SIGNIFICANTLY BEFORE MOVING OVER THE VALLEY. CHANCES FOR
THUNDERSTORMS OVER THE VALLEY HAVE DIMINISHED TO ONLY 5-10% WITH
LIGHT SHOWERS MOST LIKELY OUTCOME, MAINLY ALONG AND EAST OF I-5.
THIS ALSO MEANS THE CONCERN FOR HEAVY RAINFALL OVER THE VALLEY
HAS DIMINISHED, THOUGH THIS STILL REMAINS A CONCERN OVER THE
CASCADES. REFS AND HREF INDICATE HOURLY RAIN RATES OF 0.3-0.5
INCHES PER HOUR WITH MANY MEMBERS INDICATING RAIN RATES OF
0.6-0.8 INCHES PER HOUR. THESE RATES COULD CAUSE LOCALIZED
POOR-DRAINAGE FLOODING AND PONDING, AND WOULD ALSO RAISE
CONCERNS FOR LANDSLIDES IN MORE SUSCEPTIBLE TERRAIN IF HEAVIER
RATES OCCUR.
FRIDAY BRINGS A NOTABLE CHANGE AS THE CA LOW FINALLY SHIFTS
EAST AND BROADER TROUGHING FROM THE NORTHEASTERN PACIFIC DEEPENS
INTO THE PACNW. SHOWER CHANCES PERSIST INTO FRIDAY MORNING,
THEN BECOME MORE FOCUSED OVER THE CASCADES BY THE AFTERNOON,
BECOMING DRY BY SATURDAY. TEMPERATURES DROP BACK INTO THE MID
60S FOR MANY INTERIOR LOWLAND LOCATIONS FRIDAY INTO SATURDAY.
LOOKING BEYOND THE COOL-DOWN, GUIDANCE FAVORS DRIER CONDITIONS
INTO NEXT WEEK WITH ANOTHER BRIEF WARMING TREND SUNDAY INTO
WEDNESDAY. TEMPERATURES RISE BACK INTO THE LOW 70S SUNDAY, LOW
TO MID 80S MONDAY, AND UPPER 80S TO LOW 90S BY TUESDAY.
TEMPERATURES BEGIN FALLING WEDNESDAY, THOUGH STILL REMAIN WARMER
IN THE UPPER 70S TO LOW 80S. CURRENT PROBABILISTIC GUIDANCE
HAS SOMEWHAT DECREASED CHANCES OF TEMPERATURES REACHING 90+
EARLY NEXT WEEK. CHANCES ON MONDAY ARE NOW 10-25% AROUND AND
NORTH OF SALEM. TUESDAY STILL LOOKS TO BE THE WARMEST DAY
WITH 30-50% CHANCES AROUND AND NORTH OF SALEM. THERE'S ONLY A
5-10% CHANCE IN THE PORTLAND METRO AREA ON WEDNESDAY. HEATRISK
HAS DECREASED TO MINOR FOR MONDAY AND WEDNESDAY WITH MODERATE
HEATRISK FOR THE PORTLAND/VANCOUVER METRO AREA AND LOWER
COLUMBIA AND COWLITZ VALLEYS ON TUESDAY. PROBABILITIES FOR MAJOR
HEATRISK ARE NOW LESS THAN 5% EACH DAY. -03/12
AVIATION
THIS EVENING, ONSHORE FLOW AT THE SURFACE ACCOMPANIED
BY A UPPER-LEVEL LOW OVER SOUTHERN OREGON/NORTHERN CALIFORNIA
CONTINUES TO DRIVE OUR WEATHER AND FLIGHT CONDITIONS. THE LATTER
FEATURE HAS FACILITATED A WIDE SWATH OF HIGH BASED SHOWERS AND
WEAK THUNDERSTORMS ACROSS THE CASCADES WHICH IS ATTEMPTING TO
SLOWLY WORK EAST TO WEST TOWARDS THE INLAND TERMINALS ALONG THE
I-5 CORRIDOR. HOWEVER, AS THIS ACTIVITY PROGRESSES, IT SHOULD
CONTINUE TO SLOWLY DOWN AND DECAY WITH THIS TREND CONTINUING
OVERNIGHT. KTTD, KSLE, AND KEUG HAVE THE BEST CHANCES (~30%) FOR
SHOWERS TO WANDER OVERHEAD BETWEEN 06-12Z WHILE SITES FURTHER WEST
TREND DRIER.
OTHERWISE, ONSHORE FLOW NEAR THE SURFACE HAS BROUGHT A MIX
OF IFR/LIFR CONDITIONS TO THE COAST WITH LOW CLOUDS ATTEMPTING TO
SLOWLY INLAND BY THE SUNRISE HOURS. CHANCES FOR MVFR CIGS AT
INLAND TERMINALS INCREASE TO 40-60% AFTER 10-12Z, ALTHOUGH VFR
CONDITIONS ARE HEAVILY FAVORED TO RETURN AFTER ~18Z. COAST SITES
MAY SEE SOME IMPROVEMENT TO MVFR OR VFR AFTER 18-20Z UNTIL
CONDITIONS DEGRADE AGAIN IN THE EVENING.
KPDX AND APPROACHES...VFR CONDITIONS PERSIST THROUGH MUCH OF THE
OVERNIGHT HOURS WITH A 20% CHANCE FOR LIGHT RAINFALL AROUND
09-12Z - THE BULK OF ACTIVITY REMAINS JUST EAST OF THE TERMINAL.
CHANCES FOR MVFR CIGS PEAK 12-16Z AROUND 50-60% BEFORE VFR
CONDITIONS BECOME FAVORED AGAIN. -99
MARINE
HIGH PRESSURE OFFSHORE WILL MAINTAIN BREEZY NORTH TO
NORTHWESTERLY WINDS ACROSS THE COASTAL WATERS THROUGH FRIDAY.
EXPECT FREQUENT GUSTS TO AROUND 20-25 KT. SEAS AROUND 10 TO 12
FT WILL PERSIST THROUGH THE OVERNIGHT HOURS. WAVE HEIGHTS THEN
GRADUALLY SUBSIDE BACK DOWN TO AROUND 7 TO 8 FT BY FRIDAY
EVENING. A SMALL CRAFT ADVISORY FOR ALL COASTAL WATERS INCLUDING
THE COLUMBIA RIVER BAR WILL REMAINS IN EFFECT UNTIL 11 AM
FRIDAY. HIGH PRESSURE IS EXPECTED TO STRENGTHEN THIS WEEKEND
ACROSS THE COASTAL WATERS LEADING TO A RETURN OF BREEZY
NORTHERLY WINDS ON SUNDAY. THERE IS A 50-80+% FOR WIND GUSTS TO
REACH SMALL CRAFT ADVISORY CRITERIA SUNDAY AFTERNOON, WITH THE
HIGHER PROBABILITIES SOUTH OF CAPE FALCON DOWN TO FLORENCE. SEAS
CONTINUE TO DROP TO AROUND 5 FEET BY SUNDAY NIGHT. -19/12
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 11 AM PDT FRIDAY FOR PZZ210-251>253-
271>273.
WWW.WEATHER.GOV/PORTLAND
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