035
FXUS66 KPQR 012155
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
255 PM PDT MON JUN 1 2026
SYNOPSIS
HIGH PRESSURE WILL MAINTAIN VERY WARM AND DRY
CONDITIONS THROUGH TUESDAY. MODERATE HEATRISK IS EXPECTED ALONG
THE I-5 CORRIDOR NORTH OF SALEM, INCLUDING THE PORTLAND/VANCOUVER
METRO. COOLER TEMPERATURES RETURN WEDNESDAY TO THURSDAY AS A
WEAK SHORTWAVE TROUGH SWINGS THROUGH THE REGION. SLIGHT CHANCES
FOR SHOWERS ALONG THE COAST, COAST RANGE, AND CASCADES ON
WEDNESDAY. COOL TREND CONTINUES AT THE END OF THE WEEK AS A
DEEPER TROUGH ARRIVES FROM THE GULF OF ALASKA, RETURNING
WIDESPREAD CHANCES FOR RAIN FRIDAY INTO THE WEEKEND.
SHORT TERM...TODAY THROUGH TUESDAY NIGHT
SATELLITE IMAGERY
AND SURFACE OBSERVATIONS AS OF EARLY MONDAY AFTERNOON DEPICTS
MOSTLY SUNNY SKIES ACROSS NORTHWEST OREGON AND SOUTHWEST
WASHINGTON AS UPPER LEVEL RIDGING AMPLIFIES OFFSHORE.
TEMPERATURES ARE ON TRACK TO RISE INTO THE LOW TO MID 80S ACROSS
INTERIOR VALLEYS TODAY. HEATRISK IS GENERALLY "MINOR," ASIDE
FROM THE DIRECT PORTLAND METRO WHERE HEATRISK IS MODERATE. THIS
MEANS THAT THE HEAT WILL AFFECT THOSE WHO ARE SENSITIVE TO HEAT,
ESPECIALLY THOSE WITHOUT COOLING/HYDRATION. WHILE DAYTIME HIGHS
WILL BE WARM, OVERNIGHT LOWS WILL BE IN THE MID TO UPPER 50S.
NOT QUITE COLD, BUT COOL ENOUGH FOR RELIEF.
TUESDAY IS THE PEAK OF THE HEAT WITH THE HIGH PRESSURE REACHING
IT'S MAXIMUM INTENSITY. THE AXIS OF THE RIDGE SHIFTS OVER
WESTERN OREGON AND WASHINGTON TUESDAY AFTERNOON. EASTERLY WINDS
ARE ALSO EXPECTED TO INCREASE OUT OF THE COLUMBIA RIVER GORGE
TUESDAY MORNING AS THERMAL TROUGHING SETS UP, BRINGING DRIER
AIR. THE EASTERLY FLOW COMBINED WITH DOWNSLOPING FROM THE
CASCADES OF THE WARM TEMPERATURES ALOFT WILL BE EVEN MORE
HEATING. EXPECT AFTERNOON TEMPERATURES ON TUESDAY TO RISE BY
AROUND 5-7 DEG F COMPARED TO TODAY WITH URBAN AREAS SITTING IN
THE LOW 90S AND THE OTHER INLAND LOWLANDS CLOSER TO 85-90 DEG F.
CHANCES FOR EXCEEDING 90 DEG F ARE AROUND 75-90% FOR THE
GREATER PORTLAND/VANCOUVER METRO AREA, 50-70% FOR THE COWLITZ
VALLEY AND CENTRAL WILLAMETTE VALLEY, AND 5-10% FOR THE SOUTHERN
WILLAMETTE VALLEY AND UPPER HOOD RIVER VALLEY. MODERATE
HEATRISK IS MUCH MORE WIDESPREAD SHIFTING INTO THE LOWER I-5
CORRIDOR AND SOUTH TOWARDS SALEM. THEREFORE, TAKE PRECAUTIONS ON
TUESDAY IF PARTICIPATING IN OUTDOOR ACTIVITIES, ESPECIALLY
DURING PEAK AFTERNOON HEATING. OVERNIGHT LOWS TUESDAY NIGHT INTO
WEDNESDAY NIGHT GENERALLY REMAIN BELOW 60 DEG F, HOWEVER, THERE
IS STILL A 20% CHANCE THAT WEDNESDAY MORNING LOWS REMAIN ABOVE
60 DEGREES ACROSS THE PORTLAND/VANCOUVER METRO. THE HEAT IS NOT
EXPECTED TO LAST LONG, AS A DECENT MARINE PUSH IS EXPECTED BY
LATER TUESDAY EVENING AHEAD OF AN UPPER SHORTWAVE TROUGH.
ANOTHER CONSIDERATION IS THE IMPACT OF THE OFFSHORE FLOW ON BOTH
MONDAY AND TUESDAY. THIS EASTERLY FLOW WILL CAUSE HUMIDITY TO
DROP CONSIDERABLY DURING THE DAY WITH MINIMUM HUMIDITY REACHING
THE TEENS IN SOME LOCATIONS NEAR THE MOUTH OF THE COLUMBIA RIVER
GORGE. OUTSIDE OF THE COAST, CANNOT RULE OUT HUMIDITY AROUND
20-25%. THESE VALUES ARE FAIRLY DRY FOR THIS TIME OF YEAR AND
THEREFORE YOU SHOULD REFER TO YOUR LOCAL AUTHORITIES FOR ANY
KIND OF BURNING RESTRICTIONS. -10/27
LONG TERM...WEDNESDAY THROUGH SUNDAY
A PATTERN CHANGE TOWARD
COOLER WEATHER ARRIVES WEDNESDAY TO THURSDAY. IF YOU HAVE BEEN
TRACKING THE FORECAST OVER THE LAST FEW DAYS, YOU KNOW THAT
THERE IS A LOW PRESSURE SYSTEM AND NEGATIVELY TILTED TROUGH
POSITIONED OVER THE NORTHEAST PACIFIC NEAR THE ALEUTIANS AND
GULF OF ALASKA. BEGINNING WEDNESDAY, THIS LOW WILL ADVECT COOLER
AIR OVER THE REGION AND ENHANCE ONSHORE FLOW AS A SURFACE FRONT
FROM A SHORTWAVE TROUGH SWINGS THROUGH. MODEL GUIDANCE
CONTINUES TO SUGGEST THAT THIS FRONT DECAYS AS IT ENTERS THE
PACIFIC NORTHWEST; THEREFORE, IMPACTS WILL BE MINIMAL IN THE WAY
OF POTENTIAL PRECIPITATION. HOWEVER, WE WILL SEE RELIEF FROM
WARMING TEMPERATURES WITH HIGH TEMPERATURES DROPPING BY AROUND
15 DEG F ON WEDNESDAY DUE TO INCREASING CLOUD COVER. ONSHORE
FLOW RETURNS, LEADING TO A WIND SHIFT TO WESTERLY WINDS,
BREEZIEST THROUGH THE CENTRAL COLUMBIA RIVER GORGE AND UPPER
HOOD RIVER VALLEY. DESPITE THE LIMITED MOISTURE, THIS FRONTAL
BAND WILL STILL BRING A 15-30% CHANCE FOR SHOWERS ALONG THE
COAST, COAST RANGE, AND CASCADES WEDNESDAY TO THURSDAY MORNING,
WHILE CHANCES FOR MEASURABLE PRECIPITATION REMAIN UNDER 10% FOR
INTERIOR VALLEYS.
FRIDAY INTO THE WEEKEND, THE MAJORITY OF ENSEMBLE MEMBERS (>80%)
ARE SUGGESTING THAT THE BROAD UPPER TROUGH NEAR THE GULF OF
ALASKA WILL TRACK SOUTHEASTWARD INTO THE PACIFIC NORTHWEST. IN
GENERAL, THERE ARE INCREASING CHANCES FOR RAIN ON FRIDAY AND
SATURDAY AS ANOTHER FRONT SWINGS THROUGH, BUT VERY LOW CHANCES
FOR ANY IMPACTFUL WEATHER. IT'S NOT UNTIL SUNDAY WHERE THE
ENSEMBLE GUIDANCE BEGINS TO SHOW UNCERTAINTY IN THE EXACT
PROGRESSION OF THE TROUGH. WHILE WE HAVE HIGHER CONFIDENCE FOR
ONSHORE FLOW, COOLER TEMPERATURES, AND MORE WET WEATHER AT THE
END OF THE WEEK, THERE IS STILL UNCERTAINTY WITH EXACT
PRECIPITATION AMOUNTS. ENSEMBLE GUIDANCE SUGGESTS 24-HOUR
RAINFALL ACCUMULATION COULD RANGE ANYWHERE FROM 0.01-0.10 (10TH
AND 25TH PERCENTILES) UP TO 0.35-0.70 (CLOSER TO THE 90TH
PERCENTILE). SHOWERS THAT LINGER ON SUNDAY WILL BE LIGHT.
-10/27
AVIATION
OFFSHORE HIGH PRESSURE WILL BEGIN TO MOVE ONSHORE
THROUGH THE PERIOD, SUPPORTING CONTINUED VFR FLYING CONDITIONS
ACROSS THE AIRSPACE. LARGELY CLEAR SKIES ASIDE FROM FEW-SCT HIGH
CIRRUS AT OR ABOVE 25 KFT WILL PERSIST THROUGH TONIGHT. DIURNAL
NORTH TO NORTHWEST WINDS OF 8-12 KT INLAND AND 10-15 KT WITH
GUSTS AS HIGH AS 20-25 KT ALONG THE COAST WILL EASE BELOW 5 KT
OUT OF THE NORTH TO NORTHEAST TONIGHT. STRONGER EAST WINDS
AROUND 10 KT ARE EXPECTED TO DEVELOP TONIGHT IN THE CASCADES AND
THROUGH EAST- WEST ORIENTED TERRAIN GAPS, INCLUDING ALONG AND
WEST OF THE COLUMBIA RIVER GORGE AS FAR AS KTTD, AND POSSIBLY TO
KPDX BY TUESDAY AFTERNOON.
KPDX AND APPROACHES...VFR CONDITIONS EXPECTED THROUGHOUT THE
PERIOD BENEATH LARGELY CLEAR SKIES ASIDE FROM FEW-SCT HIGH
CIRRUS AT OR ABOVE 25 KFT. DIURNAL NORTH TO NORTHWEST WINDS
NEAR 10 KT WILL EASE BELOW 5 KT BY 03-06Z TUE. EAST WINDS OF
10-15 KT WILL DEVELOP ALONG THE COLUMBIA RIVER GORGE REACHING
WEST TO KTTD TONIGHT, AND POSSIBLY TO KPDX AFTER 12Z TUE. -36
MARINE
SURFACE HIGH PRESSURE OFFSHORE CONTINUES TO SUPPORT
GUSTY NORTH WINDS TODAY, BEFORE IT WEAKENS AND MOVES INLAND ON
TUESDAY. SMALL CRAFT ADVISORIES REMAIN IN EFFECT SOUTH OF CAPE
FALCON, WHERE THE STRONGEST GUSTS UP TO 25 KT WILL PEAK THIS
AFTERNOON, UNTIL 11 PM PDT THIS EVENING WHEN WINDS EASE BELOW
HAZARDOUS THRESHOLDS. NORTHWEST WINDS NEAR 10 KT WILL OTHERWISE
CONTINUE THROUGH TUESDAY, BEFORE TURNING SOUTHWESTERLY AHEAD OF
A DECAYING FRONT TUESDAY NIGHT INTO WEDNESDAY. RAIN SHOWER
CHANCES INCREASE TO 20-45% BEYOND 20-30 NM WEDNESDAY MORNING,
BEFORE WINDS BACK OUT OF THE NORTHWEST BY WEDNESDAY AFTERNOON
BEHIND THE BOUNDARY. SEAS OF 4-7 FT AT 8-10 SECONDS WITH A
DOMINANT WNW SWELL CONTINUE THROUGH MIDWEEK.
TROUGHING LOOKS TO REMAIN OVER THE NORTHEAST PACIFIC RESULTING
IN UNSETTLED WEATHER THROUGH THE REMAINDER OF THE PERIOD. THE
DOMINANT SWELL WILL SHIFT OUT OF THE WEST, WITH SEAS RISING TO
6-9 FT AT 10-12 SECONDS INTO THE WEEKEND. NORTHWEST WINDS
PERSIST THROUGH FRIDAY MORNING, WHEN ANOTHER FRONT MAY BRING
FURTHER RAIN CHANCES INTO THE WEEKEND. -36
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR PZZ252-253-
272-273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
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X.COM/NWSPORTLAND
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