717
FXUS66 KPQR 230522 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE PORTLAND OR
1022 PM PDT THU OCT 22 2026
UPDATED AVIATION DISCUSSION AND WATCHES/WARNINGS/ADVISORIES SECTION.
SYNOPSIS
DRY WEATHER IS EXPECTED THROUGH MUCH OF SATURDAY,
BEFORE RAIN CHANCES INCREASE THROUGH THE LATTER HALF OF THE
WEEKEND. PERSISTENT SEASONABLE TEMPERATURES THROUGH THE PERIOD.
DISCUSSION...NOW THROUGH THURSDAY
A WEAK UPPER SHORTWAVE
PASSING OVERHEAD THIS AFTERNOON WILL REINFORCE ONSHORE FLOW,
ALLOWING FOR CONTINUED SEASONABLE TEMPERATURES THROUGH THE
COMING DAYS, BUT IS UNLIKELY TO PRODUCE RAINFALL. MEANWHILE, A
CUTOFF LOW OVER CALIFORNIA IS TRANSPORTING MOISTURE NORTHWARD
ON ITS EASTERN FLANK TOWARD EASTERN/CENTRAL OREGON, WHICH MAY
PRODUCE LIGHT RAIN SHOWERS THROUGH THIS EVENING IN THE NORTH AND
CENTRAL OREGON CASCADES. MUCH OF THE PRECIPITATION EVIDENT ON
AREA RADAR IS EVAPORATING BEFORE IT REACHES THE SURFACE, WITH
THE MAJORITY OF OBSERVED RAINFALL EAST OF THE CASCADE CREST
MEASURING 0.1 INCHES OR LESS. IF ANY RAIN DOES REACH THE GROUND
WEST OF THE CREST, IT WILL LIKELY ALSO ONLY MANAGE TO ADD UP TO
A FEW HUNDREDTHS OF AN INCH. AS SKIES CLEAR WEST OF THE CASCADES
TONIGHT, EFFICIENT RADIATIVE COOLING WILL ALLOW TEMPERATURES TO
FALL INTO THE LOW TO MID 30S AWAY FROM THE COAST AND FROM URBAN
AREAS, YIELDING WIDESPREAD CHANCES FOR FROST AND, WITHIN THE
SOUTHERN WILLAMETTE VALLEY AND SHELTERED COAST RANGE VALLEYS,
LOCAL AREA WHERE A FREEZE IS EXPECTED. FREEZE WARNINGS HAVE
THEREFORE BEEN ISSUED FROM 11 PM PDT THIS EVENING UNTIL 9 AM PDT
FRIDAY FOR PORTIONS OF LANE, BENTON, AND LINN COUNTIES WITHIN
THE WILLAMETTE VALLEY AS WELL AS INTERIOR VALLEYS OF THE
NORTHERN COAST RANGE INCLUDING NEAR VERNONIA AND GRAND RONDE.
FROST ADVISORIES ALSO REMAIN IN EFFECT FOR THE SAME TIMES
ELSEWHERE IN THE COAST RANGE, CENTRAL WILLAMETTE VALLEY, AND
INTERIOR SOUTH WASHINGTON LOWLANDS. THOSE WITH AGRICULTURAL
INTERESTS OR SENSITIVE OUTDOOR PLANTS SHOULD TAKE ACTION TO
PREVENT DAMAGE.
THERE IS THEN HIGH CONFIDENCE THAT DRY WEATHER RETURNS TONIGHT
THROUGH MUCH OF SATURDAY AS TRANSIENT UPPER RIDGING TRAVERSES
THE REGION. AS THE RIDGE AXIS SHIFTS INLAND ON FRIDAY NIGHT,
LIGHT OFFSHORE FLOW, PEAKING OVERNIGHT IN THE CASCADES AND COAST
RANGE, WILL SEE DAYTIME TEMPERATURES WARM SLIGHTLY ON SATURDAY,
BUT WILL GENERALLY REMAIN NEAR SEASONAL NORMS WITH AFTERNOON
HIGH TEMPERATURES IN THE 50S ON THE COAST AND IN TERRAIN, AND IN
THE LOW TO MID 60S WITHIN INLAND VALLEYS. OVERNIGHT TEMPERATURES
WILL AGAIN FALL INTO THE LOW TO MID 30S FOR MANY AWAY FROM THE
COAST ON FRIDAY NIGHT, WITH FREEZE WATCHES AND FROST ADVISORIES
REMAINING IN EFFECT; FREEZE WATCHES MAY BE UPGRADED TO FREEZE
WARNINGS IF CONFIDENCE INCREASES IN TEMPERATURES FALLING TO NEAR
OR BELOW FREEZING.
THERE REMAINS GOOD CONSENSUS AMONG LONG-RANGE ENSEMBLES THAT
ANOTHER CUTOFF LOW WILL DEVELOP OVER THE GULF OF ALASKA ON
SATURDAY AND TRACK TO THE SOUTHEAST OFFSHORE OF VANCOUVER
ISLAND. BY SUNDAY, THERE IS LESS AGREEMENT ON HOW THE LOW WILL
EVOLVE AS IT NEARS THE PACIFIC NORTHWEST. FOR NOW, THERE ARE
MODEST CHANCES, NEAR 50%, FOR RAIN ON SUNDAY ACROSS THE REGION,
DECREASING THROUGH THE FIRST HALF OF NEXT WEEK AS TROUGHING MAY
LINGER OVERHEAD. COOL AIR ALOFT WILL ALSO LIKELY CONTINUE TO
SUPPORT SEASONABLE TEMPERATURES FOR LATE OCTOBER. -36
AVIATION...THROUGH 06Z FRIDAY
THE SURFACE FRONT HAS MOVED EAST
OF THE CASCADES AS OF 05Z FRI. ELEVATED WINDS DUE TO THE FRONTAL
PASSAGE HAVE BEEN DECREASING, AND MOST TERMINALS SHOULD OBSERVE
WINDS BELOW 8 KTS BY 06-10Z THU. WINDS ALONG THE COAST WILL REMAIN
NORTH TO NORTHWESTERLY WHILE WINDS IN INTERIOR VALLEYS WILL BECOME
VARIABLE. MAINLY VFR CONDITIONS BEING OBSERVED AT INLAND TERMINALS,
THOUGH SATELLITE IMAGERY DEPICTS LOW STRATUS ALONG THE SW WA
CASCADES PUSHING SOUTH TOWARDS THE VANCOUVER AND PORTLAND METRO
AREAS. THERE'S A 40-60% CHANCE THAT MVFR CIGS IMPACT KPDX, KTTD,
KUAO, AND SURROUNDING TERMINALS AT ANY HOUR BETWEEN 05-14Z FRI.
ADDITIONALLY, THERE'S A 15-25% CHANCE OF MVFR CIGS AROUND KSLE,
KEUG, AND SURROUNDING TERMINALS CLOSER TO SUNRISE, BETWEEN 12-17Z
FRI. IN TERMS OF FOG FORMATION, CHANCES FOR SURFACE VISIBILITIES
LESS THAN 5 SM AT ALL TAF SITES REMAIN LESS THAN 10% AS IT APPEARS
WINDS WILL REMAIN JUST STRONG ENOUGH TO PREVENT FOG DEVELOPMENT.
TEMPERATURES IN THE LOW TO MID 30S ACROSS THE REGION MAY RESULT IN
FROST DEVELOPMENT OVER METAL SURFACES BETWEEN 08-17Z FRI.
KPDX AND APPROACHES...PREDOMINATELY VFR CONDITIONS EXPECTED THROUGH
THE TAF PERIOD. THERE'S A 40-60% CHANCE OF MVFR CIGS AT ANY HOURS
BETWEEN 05-14Z THU AS STRATUS OBSERVED TO THE NORTH AT 05Z THU
PUSHES SOUTH. LIGHT AND VARIABLE WINDS EXPECTED THROUGH THE TAF
PERIOD. -03
MARINE
BUOY OBSERVATIONS FROM 2 PM PDT THURSDAY SHOWED
NORTHERLY WINDS INCREASING BEHIND A COLD FRONTAL PASSAGE, WITH
SUSTAINED WINDS BETWEEN 15 AND 25 KT AND GUSTS UP TO 30 KT. SEAS
WERE BEGINNING TO GRADUALLY INCREASE AS A NORTHWEST SWELL
CONTINUES TO BUILD OVER THE WATERS. SEAS ARE EXPECTED TO CONTINUE
BUILDING THIS EVENING, BECOMING STEEP AND HAZARDOUS SHORTLY AFTER
SUNSET. SEAS WILL THEN REMAIN STEEP AND HAZARDOUS THROUGH EARLY
FRIDAY MORNING WITH SIGNIFICANT WAVE HEIGHTS RANGING BETWEEN 8 AND
12 FT AND WAVE PERIODS BETWEEN 8 AND 10 SECONDS. SMALL CRAFT
ADVISORIES REMAIN IN PLACE FOR ALL MARINE ZONES UNTIL 8 PM PDT
THURSDAY, BEFORE RAMPING UP TO A HAZARDOUS SEAS WARNING LASTING
FROM 8 AM PDT THURSDAY UNTIL 8 AM PDT FRIDAY FOR ALL MARINE
ZONES, EXCEPT THE MAIN CHANNEL OF THE COLUMBIA RIVER BAR WHERE A
SMALL CRAFT ADVISORY IS IN EFFECT NOW THROUGH 8 AM PDT FRIDAY.
SEAS WILL BE RELATIVELY LESS STEEP OVER THE COLUMBIA RIVER BAR
WITH SIGNIFICANT WAVE HEIGHTS OF 7 TO 9 FT AT 8 TO 10 SECONDS, BUT
WILL STILL BE HAZARDOUS TO SMALL CRAFT, ESPECIALLY DURING EBB
CURRENTS. IT IS ALSO WORTH NOTING THAT BRIEF AND ISOLATED WIND
GUSTS AS HIGH AS 35 KT ARE POSSIBLE THROUGH 10 PM PDT THURSDAY
OVER THE COLUMBIA RIVER BAR, BUT WIND GUSTS OF THIS MAGNITUDE ARE
NOT EXPECTED TO BE FREQUENT ENOUGH TO JUSTIFY THE ISSUANCE OF A
GALE WARNING.
NORTH WINDS WEAKEN LATE FRIDAY MORNING INTO THE AFTERNOON WITH A
CONTINUED NORTHWEST SWELL AND SEAS BECOMING LESS STEEP. NORTH
WINDS WILL THEN PERSIST THROUGH AT LEAST SATURDAY AFTERNOON AS AN
APPROACHING LOW STALLS WEST OF THE COASTAL WATERS. THERE IS STILL
UNCERTAINTY ON THE EXACT STRENGTH AND TRACK OF THIS LOW HEADING
INTO SATURDAY NIGHT AND SUNDAY. DESPITE THIS UNCERTAINTY, CONFIDENCE
IS HIGH WIND SPEEDS WILL STAY BELOW GALE-FORCE, AS PROBABILITIES
FOR WIND GUSTS OF 34 KT OR STRONGER ARE NOW LESS THAN 10% THIS
WEEKEND. PROBABILITIES FOR SEAS OVER 10 FT REACH 10-20% SUNDAY
MORNING AND AFTERNOON. -23
PQR WATCHES/WARNINGS/ADVISORIES
OR...FROST ADVISORY FROM 11 PM FRIDAY TO 9 AM PDT SATURDAY FOR
ORZ101>103-105-107>109-111>113-119-123.
FREEZE WARNING UNTIL 9 AM PDT FRIDAY FOR ORZ104-116>118.
FREEZE WATCH FROM FRIDAY EVENING THROUGH SATURDAY MORNING FOR
ORZ104-106-114>118-124-125.
FROST ADVISORY UNTIL 9 AM PDT FRIDAY FOR ORZ105>107-109-114-115-
124-125.
WA...FROST ADVISORY FROM 11 PM FRIDAY TO 9 AM PDT SATURDAY FOR
WAZ203>208.
FROST ADVISORY UNTIL 9 AM PDT FRIDAY FOR WAZ203>205-208.
PZ...SMALL CRAFT ADVISORY UNTIL 8 AM PDT FRIDAY FOR PZZ210.
HAZARDOUS SEAS WARNING UNTIL 8 AM PDT FRIDAY FOR PZZ251>253-
271>273.
SMALL CRAFT ADVISORY FROM 8 AM TO 5 PM PDT FRIDAY FOR
PZZ251>253-271>273.
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