595
FXUS66 KPQR 211006
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
ISSUED BY NATIONAL WEATHER SERVICE SEATTLE WA
306 AM PDT WED MAY 21 2025
SYNOPSIS
THE RECENT COOL AND WET WEATHER WILL CONTINUE
THROUGH THE END OF THE WEEK AND GIVE WAY TO DRIER WEATHER AND
ABOVE AVERAGE TEMPERATURES AS WE MOVE INTO THE WEEKEND.
SHORT TERM...NOW THROUGH THURSDAY
SHOWERS HAVE ENDED
THROUGHOUT THE REGION AS OF 2:30AM WEDNESDAY, AND A BRIEF PERIOD
OF RIDGING IS EXPECTED FOR THE REST OF TONIGHT AND WEDNESDAY
DAYTIME HOURS. WITH SOME ISOLATED CLEARING TONIGHT, THERE EXISTS
A 50-60% CHANCE OF FROST DEVELOPING IN COLD POCKETS THAT FORM
TONIGHT, PARTICULARLY THE UPPER HOOD RIVER VALLEY (ODELL,
PARKDALE). THAT SAID, MOST OF THE WILLAMETTE VALLEY SHOULD
REMAIN CLOSER TO THE UPPER 30S/NEAR 40S TONIGHT AS CLOUD COVER
INHIBITS FROST FORMATION.
WEDNESDAY REMAINS DRY WITH ELEVATED TEMPERATURES IN THE
AFTERNOON. HIGH TEMPS IN THE UPPER 60S/NEAR 70 IN THE WILLAMETTE
VALLEY, WITH COASTAL TEMPERATURES CLOSER TO THE UPPER 50S/NEAR
60. RIDGING WILL BE FAIRLY SHORT LIVED AS A WEAK SHORTWAVE
TROUGH PUSHES INTO THE REGION WEDNESDAY NIGHT, BRINGING SOME
WEAK INSUBSTANTIAL RAIN SHOWERS OVER WEDNESDAY NIGHT AND
THURSDAY AM HOURS, ENDING IN THE AFTERNOON. TEMPERATURES ON
THURSDAY WILL BE SLIGHTLY DEPRESSED COMPARED TO WEDNESDAY, WITH
TEMPERATURES CLOSER TO THE LOW TO MID 60S IN THE WILLAMETTE
VALLEY.
BRIEF RIDGING LATE TONIGHT INTO EARLY WEDNESDAY WILL GIVE WAY TO
ANOTHER SHORTWAVE TROUGH SLIDING ACROSS THE REGION LATE
WEDNESDAY INTO EARLY THURSDAY. THIS WILL BRING ANOTHER ROUND OF
LIGHT PRECIPITATION TO THE REGION. ENSEMBLES SUGGEST THE LIGHT
RAIN IS MOST LIKELY TO ARRIVE WEDNESDAY EVENING INTO WEDNESDAY
NIGHT WITH SOME LIGHT PRECIPITATION CHANCES LINGERING INTO
THURSDAY ACROSS MAINLY THE HIGHER TERRAIN. TEMPERATURES LOOK TO
REMAIN NEAR TO SLIGHTLY BELOW AVERAGE FOR THE DATE THROUGH
THURSDAY.
LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
WPC CLUSTERS
SUGGEST THE REGION WILL BE UNDER THE INFLUENCE OF A LINGERING
SHORTWAVE TROUGH THURSDAY NIGHT INTO FRIDAY. HOWEVER, ONLY
10-30% OF GLOBAL ENSEMBLE MEMBERS SUGGEST DEEP ENOUGH TROUGHING
OVER THE REGION TO KEEP SOME LIGHT PRECIPITATION CONTINUING
MAINLY OVER THE NORTHERN HALF OF THE CWA AND THE HIGHER TERRAIN
OF THE COAST RANGE AND CASCADES. OTHERWISE, PRECIPITATION LOOKS
TOO WEAK TO REALLY PRODUCE ANY SUBSTANTIAL RAIN.
GLOBAL ENSEMBLE MEMBERSHIP IS GENERALLY IN AGREEMENT THAT
SHORTWAVE RIDGING WILL BUILD INTO THE PACIFIC NORTHWEST SATURDAY
INTO SUNDAY LEADING TO THE AREA DRYING OUT FURTHER AND
TEMPERATURES WARMING TO WELL ABOVE AVERAGE BY SUNDAY. WITH THAT
SAID, THERE IS 10-20% OF THE ENSEMBLE GUIDANCE THAT DELAYS
SHORTWAVE RIDGING, WHICH KEEPS SATURDAY COOLER.
UNCERTAINTY IN THE UPPER LEVEL PATTERN GROWS EARLY NEXT WEEK.
THE MAIN UNCERTAINTY REVOLVES AROUND HOW LONG SHORTWAVE RIDGING
PERSISTS OVER THE REGION AND WHEN THE NEXT SHORTWAVE TROUGH
SLIDES INTO THE PACIFIC NORTHWEST. THE CURRENT FORECAST IS VERY
MIDDLE OF THE ROAD, BUT KNOW THERE IS ~25% CHANCE TEMPERATURES
IN THE 80S WILL PERSIST INTO EARLY NEXT WEEK AND THERE IS A ~25%
CHANCE THAT TEMPERATURES DROP INTO THE 60S WITH.
AVIATION
SHOWERS CONTINUE TO TAPER OFF AND ARE MAINLY CONFINED
TO THE WASHINGTON COAST AND PARTS OF THE CASCADES AS OF 09Z WED
AS WEAK HIGH PRESSURE BUILDS OVER THE REGION. THIS YIELDS VFR
CONDITIONS AND LIGHT WINDS UNDER SCATTERED TO BROKEN MID LEVEL
CLOUD COVER ACROSS MUCH OF THE AREA, WITH THESE CONDITIONS
EXPECTED TO PERSIST THROUGH MUCH OF THE PERIOD. WINDS WILL
INCREASE OUT OF THE NW 18-21Z, INCREASING TO 10-15 KT AT COASTAL
SITES BUT GENERALLY REMAINING BELOW 10 KT INLAND. HIGH PRESSURE
WILL SHIFT EAST OF THE CASCADES LATE IN THE PERIOD, WITH AN
ARRIVING DISTURBANCE BRINGING INCREASING RAIN CHANCES AND LOWERING
CIGS 06-12Z THU.
PDX AND APPROACHES...MAINLY VFR CONDITIONS THROUGH THE PERIOD.
LIGHT WINDS INCREASE OUT OF THE WNW 18-21Z WED, BUT GENERALLY
REMAIN BELOW 8 KT THROUGH THE PERIOD. RAIN CHANCES INCREASE AFTER
06Z THU, BUT VFR LIKELY TO PERSIST THROUGH AT LEAST 12Z THU. /CB
MARINE
BUOY OBSERVATIONS SHOW LIGHT NORTHWEST BREEZES WITH
SEAS SUBSIDING TO 7-9 FT ACROSS THE WATERS AS OF 2 AM WEDNESDAY.
WINDS WILL TURN MORE NORTHERLY TODAY AND THURSDAY AS WEAK SURFACE
HIGH PRESSURE BUILDS OFFSHORE. INLAND DAYTIME HEATING WILL DRIVE
SOME DIURNAL STRENGTHENING OF THE COASTAL PRESSURE GRADIENT, WITH
WINDS INCREASING TO 15-20 KT DURING THE LATE AFTERNOON AND EARLY
EVENING. MODELS SUGGEST A 30-50% FOR GUSTS AS HIGH AS 25 KT OVER
THE NEARSHORE WATERS LATER THIS AFTERNOON, BUT DO NOT ANTICIPATE
ADDING ANY SMALL CRAFT HEADLINES AT THIS TIME AS GUSTS SHOULD
REMAIN FAIRLY LOCALIZED. MEANWHILE, SEAS WILL CONTINUE TO
GRADUALLY SUBSIDE THROUGH THURSDAY AS A MID PERIOD SWELL DECAYS
BELOW 5 FT. CONDITIONS REMAIN ON THE QUIET SIDE FRIDAY INTO THE
WEEKEND AS BENIGN ONSHORE FLOW RETURNS, YIELDING MAINLY LIGHT
BREEZES AND SEAS BELOW 5 FT. /CB
PQR WATCHES/WARNINGS/ADVISORIES
OR...FROST ADVISORY UNTIL 8 AM PDT THIS MORNING FOR ORZ121.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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