128
FXUS66 KPQR 112303
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
303 PM PST TUE NOV 11 2025
SYNOPSIS
A BRIEF PERIOD OF HIGH PRESSURE WILL MAINTAIN DRY CONDITIONS
THROUGH EARLY WEDNESDAY BEFORE THE NEXT FRONTAL SYSTEM
APPROACHES FROM THE PACIFIC. THIS WILL RETURN COOLER
TEMPERATURES AND WET WEATHER BY WEDNESDAY NIGHT. SNOW LEVELS ARE
EXPECTED TO FALL THURSDAY INTO EARLY FRIDAY, ALLOWING FOR
ACCUMULATING SNOW ACROSS THE CASCADE PASSES. THE ACTIVE AND
UNSETTLED PATTERN IS EXPECTED TO PERSIST THROUGH THE WEEKEND
AND LIKELY INTO EARLY NEXT WEEK.
DISCUSSION...NOW THROUGH MONDAY
TODAYS WEATHER REMAINS QUIET
UNDER A WEAK SHORTWAVE RIDGE EXTENDING ACROSS THE PACIFIC
NORTHWEST. CONDITIONS WILL STAY DRY WITH SEASONABLE TEMPERATURES
AND LIGHT NORTHERLY FLOW. MID AND HIGH-LEVEL CLOUDS WILL
GRADUALLY INCREASE THROUGH THE AFTERNOON AS THE NEXT SYSTEM
DRAWS CLOSER FROM THE PACIFIC. WINDS TURN SOUTHERLY OVERNIGHT
AND INTO WEDNESDAY AS THE RIDGE SLIDES EAST AND THE APPROACHING
TROUGH DEEPENS OFFSHORE.
BY WEDNESDAY AFTERNOON, ENSEMBLE GUIDANCE CONTINUES TO SUGGEST
A BROAD TROUGH ADVANCING FROM THE NORTHEAST PACIFIC TOWARD THE
REGION. THERE REMAINS MODERATE CONFIDENCE IN THE SURFACE LOW
TRACKING OFFSHORE NEAR THE SOUTHERN OREGON AND NORTHERN
CALIFORNIA BORDER. THE GFS AND CANADIAN SOLUTIONS REMAIN
CONSISTENT WITH THIS SOUTHERN TRACK, WHILE THE ECMWF CONTINUES
TO ENTERTAIN A SLIGHTLY MORE NORTHERN TRACK. SHOULD THE ECMWF
SOLUTION VERIFY, GUSTIER SOUTHERLY WINDS WOULD BECOME MORE
LIKELY ALONG THE CENTRAL OREGON COAST-PARTICULARLY FROM CAPE
FOULWEATHER SOUTH TO FLORENCE, AND POSSIBLY EXTEND INTO
PORTIONS OF THE SOUTHERN WILLAMETTE VALLEY. LOCALIZED IMPACTS
SUCH AS DOWNED TREE LIMBS OR ISOLATED POWER OUTAGES WOULD BE
POSSIBLE. THAT SAID, GIVEN CURRENT ENSEMBLE TRENDS ALIGNING MORE
CLOSELY WITH THE GFS AND CANADIAN GUIDANCE, THIS SCENARIO
APPEARS INCREASINGLY UNLIKELY.
AN OCCLUDED FRONT TIED TO THE SYSTEM WILL MOVE THROUGH
NORTHWEST OREGON AND SOUTHWEST WASHINGTON LATE WEDNESDAY NIGHT
INTO EARLY THURSDAY, BRINGING A RETURN TO WIDESPREAD RAIN. THE
HEAVIEST PRECIPITATION SHOULD REMAIN DISPLACED FARTHER SOUTH
TOWARD FAR NORTHERN CALIFORNIA AND SOUTHWEST OREGON. BETWEEN 4
PM WEDNESDAY AND 4 PM THURSDAY, PROBABILITIES FOR RAINFALL
EXCEEDING ONE INCH SIT AROUND 10-20% FOR INTERIOR VALLEYS AND
50-60% ALONG THE COAST, COAST RANGE, WILLAPA HILLS, AND NORTH
OREGON/SOUTH WASHINGTON CASCADES. WINDS WILL ALSO STRENGTHEN
THURSDAY WHILE TURNING MORE SOUTHERLY TO SOUTHWESTERLY, THOUGH
PROBABILITIES FOR GUSTS EXCEEDING 45 MPH REMAIN LIMITED TO
AROUND 10-15% IN INTERIOR VALLEYS AND 20-30% ALONG THE COAST.
BEHIND THE FRONT, A COOLER POST-FRONTAL AIR MASS ARRIVES
THURSDAY. FORECAST CONFIDENCE DECREASES LATE THURSDAY INTO
FRIDAY AS MODEL SOLUTIONS DIVERGE REGARDING THE DEGREE OF
COOLING AND SNOW LEVELS. CURRENT MODELS SUGGEST SNOW LEVELS
COULD RANGE FROM 3000 AND 5000 FEET, PLACING THE CASCADE PASSES
NEAR THE TRANSITION ZONE WHERE PRECIPITATION TYPE COULD VARY.
WHILE THERE IS HIGH CONFIDENCE THAT SNOW WILL OCCUR AT PASS
LEVEL, IMPACTS ARE LIKELY TO REMAIN LIMITED GIVEN THE MARGINAL
TEMPERATURES ALOFT. BETWEEN 4 AM THURSDAY AND 4 AM SATURDAY,
THERE IS A 30-40% CHANCE OF SIX INCHES OR MORE OF SNOW AT
SANTIAM AND WILLAMETTE PASSES, AND AROUND A 20-30% CHANCE NEAR
GOVERNMENT CAMP.
RAIN CONTINUES THURSDAY AS THE LOW LINGERS OVER THE REGION, AND
A FEW EMBEDDED THUNDERSTORMS CANNOT BE RULED OUT, THOUGH
INSTABILITY APPEARS MINIMAL AS CAPE VALUES ARE EXPECTED TO BE
MARGINAL. THE BROADER PATTERN STAYS ACTIVE THROUGH THE END OF
THE WEEK AND INTO THE WEEKEND. A WARM FRONT LIFTING NORTH ON
SATURDAY WILL RAISE SNOW LEVELS AND TRANSITION PRECIPITATION
BACK TO RAIN IN THE CASCADES, FOLLOWED BY ANOTHER COLD FRONT ON
SUNDAY THAT WILL LOWER SNOW LEVELS ONCE AGAIN, RETURNING SNOW
CHANCES TO THE PASSES. ELSEWHERE, PERIODIC RAIN IS EXPECTED TO
PERSIST THROUGH MONDAY UNDER CONTINUED SOUTHWEST FLOW ALOFT.
~12
AVIATION
AS OF 22Z TUE, VFR CONDITIONS HAVE RETURNED TO THE
COAST AND INLAND LOCATIONS SOUTH OF KSLE. A STRATUS SHIELD REMAINS
IN PLACE IN THE WILLAMETTE VALLEY SOUTH OF KSLE CAUSING IFR/MVFR
CIGS AND VIS. CONFIDENCE IS INCREASING THAT THIS STRATUS DECK WILL
REMAIN IN PLACE THROUGH MOST OF THE NIGHT AND INTO WEDNESDAY
MORNING. THERE COULD BE A PERIOD OF A FEW HOURS AFTER 00Z WHERE IT
LIFTS TO VFR BEFORE FILLING BACK IN AS TEMPERATURES COOL
OVERNIGHT. ELSEWHERE, THERE IS A 20-30% CHANCE OF MVFR/IFR CIGS
RETURNING AFTER 09-12Z WED. ANY LOWERED CONDITIONS SHOULD BECOME
VFR BY 18-21Z WED. WINDS WILL GENERALLY LIGHT AND VARIABLE UNDER
6 KT ACROSS ALL TERMINALS. A WEATHER SYSTEM APPROACHING THE REGION
WEDNESDAY WILL BRING A SLIGHT CHANCE OF -SHRA OR -DZ TO THE COAST
AFTER 09-12Z WED AND INLAND AFTER 18Z WED.
KPDX AND APPROACHES...PREDOMINATELY VFR CONDITIONS WITH HIGH-
LEVEL BKN/OVC CLOUDS. THERE'S A LOW (20-30%) CHANCE OF MVFR CIGS
RETURNING AFTER 09-12Z WED. NORTHWESTERLY WINDS UNDER 5 KT TURN
EASTERLY AFTER 02Z WED. -03
MARINE
HIGH PRESSURE OVER THE WATERS WILL MAINTAIN CALM MARINE
CONDITIONS THROUGH EARLY WEDNESDAY MORNING. WINDS WILL GENERALLY
REMAIN NORTHERLY WITH GUSTS LESS THAN 10 KT AND SEAS OF 5-8 FT AT
10-13 SEC.
THE NEXT LOW PRESSURE SYSTEM IN THE NE PACIFIC WILL RETURN BREEZY
SOUTHERLY WINDS AND BUILDING SEAS WEDNESDAY INTO THURSDAY, WITH
HIGH CONFIDENCE FOR ANOTHER PERIOD OF CONDITIONS HAZARDOUS TO
SMALL CRAFT. AS THIS SYSTEM SWINGS A FRONT THROUGH THE WATERS,
THERE'S A 60-80% CHANCE OF FREQUENT SOUTHERLY WIND GUSTS
EXCEEDING 21 KT AND A GREATER THAN 90% CHANCE THAT SEAS BUILD
ABOVE 10 FT BY LATE WEDNESDAY NIGHT/EARLY THURSDAY MORNING.
THEREFORE, A SMALL CRAFT ADVISORY CONTINUES FOR ALL MARINE ZONES
INCLUDING THE COLUMBIA RIVER BAR FROM 10 AM WEDNESDAY TO 10 AM
THURSDAY. DURING THIS TIME, THERE IS ALSO A 40-60% CHANCE FOR
ISOLATED GALE-FORCE WIND GUSTS GREATER THAN 34 KT, WITH THE
HIGHEST CHANCES ACROSS THE OUTER WATERS BEYOND 20-30 NM. ACTIVE
WEATHER CONTINUES INTO THE END OF THE WEEK WITH ADDITIONAL SYSTEMS
MOVING THROUGH THE WATERS. -10/03
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 10 AM WEDNESDAY TO 10 PM PST THURSDAY
FOR PZZ210-251>253-271>273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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