816
FXUS66 KPQR 241058
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
358 AM PDT SUN MAY 24 2026
SYNOPSIS
HIGH PRESSURE WILL DELIVER ONE MORE WARM, DRY DAY
TODAY, WHILE THE COAST STAYS COOLER AT TIMES UNDER PATCHES OF
MARINE CLOUDS AND DRIZZLE. CONFIDENCE REMAINS HIGH IN A SHARP
SHIFT LATE TONIGHT INTO MONDAY AS A GULF OF ALASKA SYSTEM
SPREADS WIDESPREAD RAIN, BREEZY WINDS, AND MUCH COOLER
TEMPERATURES ACROSS THE AREA. SHOWERS LINGER INTO TUESDAY WITH
A LOW-END THUNDER CHANCE, THEN CONDITIONS TREND WARMER AND DRIER
LATE NEXT WEEK.
DISCUSSION...NOW THROUGH SATURDAY
EARLY THIS SUNDAY MORNING,
THE REGION REMAINS ON THE WARM SIDE OF THE PATTERN BENEATH
UPPER-LEVEL HIGH PRESSURE. EVEN SO, ONSHORE FLOW NEAR THE
SURFACE IS STILL ENOUGH TO BRING MARINE CLOUDS BACK TO THE COAST
AND INTO SOME ADJACENT VALLEYS AT TIMES. ANY COASTAL DRIZZLE/MIST
WOULD BE CONFINED MAINLY TO THE MORNING HOURS. FOR TODAY,
TEMPERATURES WILL AGAIN RUN WARM INLAND, BUT THE FINAL OUTCOME
WILL HINGE ON HOW MUCH MARINE CLOUD COVER HANGS ON NEAR MIDDAY.
CURRENT EXPECTATIONS STILL FAVOR THE WARMEST HIGHS OF THE
WEEKEND ACROSS INTERIOR VALLEYS, GENERALLY UPPER 70S TO LOWER
80S, WHILE THE COAST STAYS COOLER IN THE LOW 60S TO LOW 70S.
CASCADES AND FOOTHILLS SHOULD STAY IN THE MID 60S TO MID 70S.
IF CLOUDS PUSH FARTHER INLAND OR LINGER LONGER THAN
ANTICIPATED THIS MORNING, SOME LOCATIONS COULD END UP 5-10
DEGREES COOLER THAN FORECAST.
THE FORECAST TURNS MUCH MORE ACTIVE LATE TONIGHT INTO MEMORIAL
DAY. A BROAD LOW DROPPING OUT OF THE GULF OF ALASKA WILL DRIVE A
FRONTAL SYSTEM INTO THE PACIFIC NORTHWEST, BRINGING WIDESPREAD
RAIN AND THICK CLOUD COVER. RAIN SHOULD BEGIN ALONG THE COAST
AROUND EARLY MONDAY MORNING, THEN SPREAD INLAND DURING LATE
MONDAY MORNING/EARLY MONDAY AFTERNOON. RECENT GUIDANCE NOW
SUPPORTS 24 HOUR RAINFALL TOTALS (ROUGHLY 5 AM MONDAY TO 5 AM
TUESDAY) IN THE 0.20 TO 0.90 INCH RANGE, WITH THE GREATEST
TOTALS AND HIGHEST PROBABILITIES ALONG THE COAST, COAST RANGE,
CASCADES, AND CASCADE FOOTHILLS. PROBABILITIES FOR AT LEAST 0.25
INCH ARE GENERALLY 50-90%, WHILE CHANCES FOR 0.50 INCH OR MORE
ARE LOWER IN THE WILLAMETTE VALLEY (5-35%) BUT REMAIN MUCH
HIGHER FOR THE COAST, COAST RANGE, AND CASCADES (AROUND 60-90%).
A CORRIDOR FROM FLORENCE OR NORTH TOWARD SEASIDE OR CONTINUES
TO SHOW THE BEST ODDS FOR 1.00 INCH OR MORE (ROUGHLY 20-40%).
WINDS WILL ALSO PICK UP EARLY MONDAY AS THE FRONT MOVES
THROUGH. CURRENTLY PROBABILITIES STRONGLY FAVOR GUSTS EXCEEDING
25 MPH ACROSS MUCH OF THE AREA (AROUND 80-99%). GUSTS OVER 30
MPH ARE MORE LIKELY ALONG THE COAST (ABOUT 70-90%) THAN INLAND
(40-60%). HIGHER-END GUSTS AROUND 35 MPH OR GREATER REMAIN A
LOWER-PROBABILITY OUTCOME INLAND (ROUGHLY 5-20%) BUT ARE MORE
PLAUSIBLE ALONG THE COAST (35-55%). EVEN WITHOUT ADVISORY-LEVEL
WINDS EXPECTED INLAND, THESE SPEEDS CAN STILL IMPACT TENTS,
CANOPIES, AND OTHER UNSECURED ITEMS.
BY TUESDAY, THE LOW SHIFTS SOUTHEAST WITH SHOWERS LINGERING AND
A MORE SOUTHERLY FLOW DEVELOPING. THAT SETUP IS MORE SUPPORTIVE
OF ISOLATED THUNDERSTORMS, AND A 15% CHANCE APPEARS REASONABLE
FOR THE WILLAMETTE VALLEY AND CASCADES BY LATE TUESDAY MORNING
INTO TUESDAY AFTERNOON. FROM MIDWEEK INTO LATE WEEK, GUIDANCE
TRENDS TOWARD A WARMING AND DRYING PATTERN AS WEAKER HIGH
PRESSURE/ZONAL FLOW RETURNS, THOUGH TEMPERATURES WILL LIKELY
REMAIN COOLER THAN THIS WEEKEND'S WARM SPELL. WHILE CONFIDENCE
REMAINS LOW, ENSEMBLE GUIDANCE SUGGESTS THAT THE WEAK HIGH
PRESSURE RIDGE WILL WEAKEN FRIDAY AS A BROAD TROUGH OVER THE
NORTHEAST PACIFIC NEARS THE PACIFIC NORTHWEST.
~12
AVIATION
HIGH PRESSURE AND HIGH CLOUDS REMAIN OVER THE
AIRSPACE, WITH VFR CONDITIONS INLAND AND MVFR CIGS ALONG THE
COAST FROM KTMK TO KAST AS OF 11Z SUN. EXPECT DETERIORATED
CONDITIONS AT THE COAST TO IMPROVE TO VFR BY 17-19Z SUN. MVFR
CIGS RETURN TO THE COAST AROUND 06Z MON AS A FRONTAL SYSTEM
APPROACHES. INLAND TERMINALS WILL STAY VFR THROUGH THE TAF
PERIOD, WITH A LESS THAN 10% CHANCE OF MVFR CIGS THROUGH AT
LEAST 12Z MON. WINDS WILL STAY NORTH TO NORTHWESTERLY UNTIL
AROUND 00Z MON, THEN SHIFT WEST TO SOUTHWESTERLY AS THE FRONTAL
SYSTEM NEARS. INLAND WINDS WILL STAY UNDER 8 KT THROUGH AT LEAST
12Z MON, WHILE COASTAL WINDS WILL INCREASE TO 8-12 KT WITH GUSTS
UP TO 20 KT BY 08-10Z MON. CONDITIONS AT INLAND TERMINALS WILL
LIKELY NOT DETERIORATE TO MVFR OR LOWER UNTIL AFTER 12Z MON.
RAIN WILL ARRIVE AT COASTAL AND INLAND TERMINALS A FEW HOURS
AFTER THE END OF THE TAF PERIOD.
KPDX AND APPROACHES...HIGH PRESSURE, HIGH CLOUDS, VFR
CONDITIONS. LESS THAN 10% CHANCE OF MVFR CONDITIONS. NORTH TO
NORTHWESTERLY WINDS UNDER 8 KT WILL SHIFT WEST TO SOUTHWESTERLY
BY 00Z MON.
~12
MARINE
BREEZY WINDS HAVE WEAKENED EARLY THIS MORNING AND WILL
CONTINUE TO WEAKEN THROUGH TODAY. SEAS WILL REMAIN AROUND 6 TO
8 FEET THROUGH TONIGHT. A FRONTAL SYSTEM WILL IMPACT THE WATERS
MONDAY INTO TUESDAY. WINDS TURN WESTERLY AND INCREASE EARLY
MONDAY MORNING AS THE FRONT APPROACHES AND MOVES THROUGH THE
WATERS. LATEST GUIDANCE INDICATES WIDESPREAD WIND GUSTS UP TO
25-30 KTS, STRONGEST NORTH OF CAPE FOULWEATHER, WITH A 35-50%
CHANCE OF GALE FORCE WIND GUSTS, MAINLY ISOLATED AND RIGHT ALONG
THE FRONTAL PASSAGE FROM 2 AM TO 8 AM MONDAY. WAVES ARE
FORECAST TO RISE BEHIND THE FRONTAL PASSAGE MONDAY AFTERNOON
INTO TUESDAY MORNING. THERE'S HIGH CONFIDENCE (90+% CHANCE) OF
SIGNIFICANT WAVE HEIGHTS EXCEEDING 13 FEET. ADDITIONALLY,
THERE'S AROUND A 25% CHANCE SIGNIFICANT WAVE HEIGHTS COULD REACH
17-19 FEET FOR LOCATIONS 20 NM AND BEYOND WEST OF THE COAST,
AND A 10% CHANCE OF 20 FEET SEAS FOR LOCATIONS 30 NM AND BEYOND
WEST OF THE COAST. AS A RESULT, A SMALL CRAFT ADVISORY HAS BEEN
ISSUED FROM 11 PM SUNDAY TO 5 AM MONDAY FOR WIND GUSTS AROUND
25 TO 30 KT. ADDITIONALLY, A HAZARDOUS SEAS WATCH HAS BEEN
ISSUED FROM 5 AM MONDAY TO 11 AM TUESDAY FOR VERY STEEP AND
HAZARDOUS SEAS, WHILE ALSO HIGHLIGHTING POSSIBLE ISOLATED GUSTS
UP TO 35 KT FROM 2 AM TO 8 AM MONDAY FOR THE WATERS NORTH OF
CAPE FOULWEATHER OR. WAVES FORECAST TO DECREASE THROUGH TUESDAY
AFTERNOON TO AROUND 10-12 FEET.
~12/03
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 5 AM PDT MONDAY
FOR PZZ210-251>253-271>273.
HAZARDOUS SEAS WATCH FROM LATE TONIGHT THROUGH TUESDAY MORNING
FOR PZZ210-251>253-271>273.
WWW.WEATHER.GOV/PORTLAND
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