331
FXUS66 KPQR 252124
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
224 PM PDT FRI SEP 25 2026
SYNOPSIS
SHOWERS AND GUSTY WINDS WILL GRADUALLY DIMINISH
THIS EVENING AS THE LOW PRESSURE SYSTEM CONTINUES TO MOVE
NORTHEAST. A COOL AND DRY PATTERN SETTLES IN FOR THE WEEKEND
AND CONTINUES INTO EARLY NEXT WEEK, WITH RENEWED CHANCES FOR
RAIN TUESDAY THROUGH THURSDAY.
DISCUSSION...NOW THROUGH THURSDAY
THE SURFACE LOW IS MOVING
NORTHEASTWARD THROUGH WASHINGTON THIS AFTERNOON, WITH THE
STRONGEST WINDS NOW SHIFTED WELL NORTHEAST OF THE REGION.
SCATTERED SHOWERS CONTINUE BEHIND THE DEPARTING FRONT AS COOL
AIR ALOFT MAINTAINS MODEST INSTABILITY ACROSS THE AREA. THE
POTENTIAL FOR THUNDERSTORMS HAS DECREASED THIS AFTERNOON, WITH
THE LATEST SPC OUTLOOK NO LONGER HIGHLIGHTING ANY PORTION OF THE
FORECAST AREA (SW WASHINGTON/NW OREGON) FOR THUNDERSTORMS. A
STRAY THUNDERSTORM CANNOT BE RULED OUT GIVEN THE LINGERING
INSTABILITY, BUT CONFIDENCE IS LOW AND THUNDERSTORMS ARE NOT
EXPECTED TO BE A SIGNIFICANT CONCERN. ANY HEAVIER SHOWERS COULD
STILL PRODUCE BRIEF GUSTY OUTFLOW. AN ISOLATED COLD-CORE FUNNEL
IS ALSO POSSIBLE, MAINLY NEAR THE COAST, ALTHOUGH SIGNIFICANT
SURFACE IMPACTS FROM THESE FEATURES ARE UNLIKELY. RAINFALL RATES
AND TOTALS REMAIN WELL BELOW LEVELS OF CONCERN FOR FLOODING.
SHOWERS WILL STEADILY DIMINISH FROM WEST TO EAST THIS EVENING,
WITH MOST AREAS WEST OF THE CASCADES DRYING OUT FIRST AND
SHOWERS LINGERING LONGEST IN THE CASCADES. CLEARING SKIES AND A
COLDER AIR MASS WILL THEN ALLOW TEMPERATURES TO FALL QUICKLY
TONIGHT. MOST LOWLAND LOCATIONS SHOULD DROP INTO THE 40S, WHILE
COLDER SPOTS IN THE HOOD RIVER VALLEY COULD FALL INTO THE UPPER
30S. THE POTENTIAL FOR FROST IS GREATER IN THE UPPER HOOD RIVER
VALLEY, PARTICULARLY AROUND DEE AND PARKDALE, WHERE CURRENT
PROBABILITIES FOR TEMPERATURES AT OR BELOW 36 DEGREES ARE AROUND
40-50%. PROBABILITIES ARE LOWER NEAR ODELL AT 5-10%. CONFIDENCE
STILL REMAINS TOO LOW FOR FROST HEADLINES, ESPECIALLY WHEN
EXPECTING CLOUD COVER OVERNIGHT TO KEEP TEMPERATURES A TAD WARMER.
SHORTWAVE RIDGING AND SURFACE HIGH PRESSURE BUILD IN BEHIND THE
DEPARTING SYSTEM, RESULTING IN DRY WEATHER FROM SATURDAY
THROUGH AT LEAST MONDAY. TEMPERATURES WILL REMAIN COOL FOR MID-
SEPTEMBER, WITH AFTERNOON HIGHS GENERALLY IN THE MID TO UPPER
60S ACROSS THE LOWLANDS. OVERNIGHT TEMPERATURES WILL ALSO REMAIN
CHILLY, PARTICULARLY UNDER CLEAR SKIES AND LIGHT WINDS ON SUNDAY
AND MONDAY, SO ADDITIONALLY FROST POTENTIAL WILL NEED TO BE
MONITORED IN THE UPPER HOOD RIVER VALLEY. CONFIDENCE IN FROST
IMPACTS DECREASES BEYOND SATURDAY MORNING AS THE DETAILS OF
CLOUD COVER AND OVERNIGHT WINDS BECOME LESS CERTAIN.
THE NEXT MEANINGFUL CHANGE IN THE PATTERN ARRIVES TUESDAY
THROUGH WEDNESDAY AS ENSEMBLE GUIDANCE INCREASINGLY FAVORS
ANOTHER UPPER-LEVEL TROUGH MOVING INTO THE PACIFIC NORTHWEST.
6 HOURLY RAIN CHANCES RISE TO ROUGHLY 20-40% DURING THIS
PERIOD, WITH HIGHER PROBABILITIES GENERALLY FAVORED ALONG THE
COAST, ACROSS NORTHERN PORTIONS OF THE FORECAST AREA (MAINLY
SOUTHWEST WASHINGTON), AND IN THE HIGHER TERRAIN. OVER A 48 HOUR
PERIOD FROM TUESDAY TO THURSDAY MORNING, THERE IS A 70-90%
CHANCE OF MEASURABLE RAINFALL AT LINCOLN CITY AND PORTLAND
NORTHWARD, AND A 30-60% CHANCE SOUTHWARD (LOWEST CHANCES TO THE
SOUTH, SUCH AS 30% AT EUGENE). CONSIDERABLE SPREAD REMAINS IN
THE STRENGTH AND POSITION OF THE TROUGH, SO PRECIPITATION TIMING
AND AMOUNTS REMAIN UNCERTAIN. ~12
AVIATION...THROUGH 00Z SUNDAY
RADAR IMAGERY AS OF EARLY FRIDAY
AFTERNOON DEPICTS SCATTERED SHOWERS ACROSS NORTHWEST OREGON AND
SOUTHWEST WASHINGTON AS A LOW PRESSURE SYSTEM EXITS THE REGION.
THERE REMAINS A 15-25% CHANCE FOR THUNDERSTORMS AT ANY GIVEN
TERMINAL THROUGH 00Z SAT. ANY PASSING THUNDERSTORMS MAY PRODUCE
LIGHTNING, HEAVY RAIN THAT CAN REDUCE VIS, GUSTY AND ERRATIC
WINDS, AND SMALL HAIL. CIGS REMAIN PREDOMINATELY LOW-END VFR
THROUGH THIS EVENING, BUT CAN'T RULE OUT SOME INTERMITTENT DROPS
TO MVFR DUE TO HEAVIER SHOWERS OR THUNDERSTORMS. EXPECT BREEZY
SOUTH/SOUTHWESTERLY WINDS THROUGH 00Z SAT WITH GUSTS UP TO 30 KT
AT ANY GIVEN TERMINAL. WINDS FURTHER WEAKEN THIS EVENING BELOW 10
KT ONCE THE SYSTEM EXITS, WITH RETURN OF DRIER CONDITIONS.
KPDX AND APPROACHES...PREDOMINATELY LOW-END VFR WITH SHOWERS
THROUGH THIS AFTERNOON. CAN'T RULE OUT INTERMITTENT DROPS TO MVFR
CIGS OR VIS DURING PERIODS OF HEAVIER SHOWERS OR THUNDERSTORMS.
SOUTHWESTERLY WINDS WITH GUSTS UP TO 25 KT THROUGH 00Z SAT,
WEAKENING BELOW 10 KT AFTER 02-03Z SAT. -10
MARINE
BREEZY WEST-NORTHWESTERLY WINDS WITH GUSTS UP TO 25 KT
CONTINUE THROUGH THIS AFTERNOON AS A ROBUST LOW PRESSURE SYSTEM
EXITS THE REGION. SEAS REMAIN STEEP AND CHOPPY AROUND 9-12 FT AT 9
SECONDS THROUGH THIS EVENING. THEREFORE, HAZARDOUS SEAS WARNINGS
REMAIN IN EFFECT FOR ALL WATERS THROUGH 5 PM THIS AFTERNOON FOR
ALL WATERS INCLUDING THE COLUMBIA RIVER BAR, TRANSITIONING TO
SMALL CRAFT ADVISORIES FROM 5-11 PM THIS EVENING. TONIGHT INTO
EARLY SATURDAY MORNING, WINDS WEAKEN BELOW 15 KT AND SEAS
GRADUALLY SUBSIDE TO 5-7 FT AT 8-9 SECONDS.
HIGH PRESSURE RE-BUILDS OVER THE WATERS ON SATURDAY, RETURNING
BREEZY NORTHERLY WINDS BY THE AFTERNOON. SMALL CRAFT ADVISORIES
HAVE BEEN ISSUED BEGINNING SATURDAY AFTERNOON/EVENING THROUGH
EARLY FRIDAY MORNING FOR STEEP AND CHOPPY SEAS OF 6-8 FT AT 8
SECONDS AND NORTHERLY WIND GUSTS UP TO 25 KT. NORTHERLY WINDS
REMAIN IN PLACE THROUGH THE WEEKEND BEFORE ANOTHER WEAK FRONT
SHIFT WINDS MORE SOUTHWESTERLY MONDAY-TUESDAY. WILL ALSO SEE A
LONGER PERIOD WEST-NORTHWESTERLY SWELL OF 5-7 FT AT 12-14 SEC
MONDAY-WEDNESDAY, RESULTING IN A MODERATE SNEAKER WAVE THREAT.
-10
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...HAZARDOUS SEAS WARNING UNTIL 5 PM PDT THIS AFTERNOON FOR PZZ210-
251>253-271>273.
SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 11 PM PDT THIS
EVENING FOR PZZ210-251>253-271>273.
SMALL CRAFT ADVISORY FROM 5 PM SATURDAY TO 5 AM PDT SUNDAY FOR
PZZ210-251-271.
SMALL CRAFT ADVISORY FROM 2 PM SATURDAY TO 5 AM PDT SUNDAY FOR
PZZ252-253-272-273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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