275
FXUS66 KPQR 111216
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
416 AM PST TUE NOV 11 2025
SYNOPSIS
BRIEF HIGH PRESSURE WILL MAINTAIN DRY WEATHER
THROUGH EARLY WEDNESDAY MORNING. BY WEDNESDAY NIGHT, A FRONTAL
SYSTEM WILL APPROACH THE REGION AND RETURN COOLER TEMPERATURES
AND WET WEATHER. SNOW LEVELS FALL THURSDAY INTO FRIDAY, LEADING
TO POTENTIAL FOR ACCUMULATING SNOW AT THE CASCADE PASSES.
UNSETTLED WEATHER IS EXPECTED TO CONTINUE THROUGH THE WEEKEND.
SHORT TERM...NOW THROUGH WEDNESDAY NIGHT
A SHORTWAVE RIDGE
WILL BUILD OVER THE PACIFIC NORTHWEST TODAY, MAINTAINING DRY
WEATHER WITH SEASONABLE TEMPERATURES AND LIGHT NORTHERLY WINDS.
WILL SEE INCREASING MID TO HIGH LEVEL CLOUD COVER AHEAD OF THE
NEXT SYSTEM. CONDITIONS WILL REMAIN PRETTY CALM ACROSS THE
REGION THROUGH EARLY WEDNESDAY MORNING.
BY WEDNESDAY AFTERNOON, THE AFOREMENTIONED UPPER RIDGE WILL
SHIFT EASTWARD AND A DEEPER UPPER TROUGH OVER THE NE PACIFIC
WILL APPROACH THE REGION. BASED ON GFS/EURO ENSEMBLE GUIDANCE,
THERE IS GENERAL AGREEMENT THAT THE SURFACE LOW PRESSURE CENTER
WILL TRACK JUST OFFSHORE OF THE SOUTHERN OREGON AND NORTHERN
CALIFORNIA BORDER. AN OCCLUDED FRONT ASSOCIATED WITH THIS LOW
WILL SWING THROUGH NORTHWEST OREGON AND SOUTHWEST WASHINGTON BY
LATE WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING, RETURNING
WIDESPREAD RAIN. SINCE THE LOW APPEARS TO TRACK FURTHER SOUTH
OF OUR AREA, THE HEAVIEST PRECIPITATION IS FORECAST TO AIM
TOWARD FAR NORTHERN CALIFORNIA AND SOUTHWEST OREGON.
CHANCES FOR 24 HOUR TOTAL RAINFALL OF 1 INCH OF GREATER FROM 4
PM WEDNESDAY TO 4 PM THURSDAY IS AROUND 15-25% ACROSS INTERIOR
LOWLAND VALLEYS, AND 60-70% ALONG THE COAST, COAST RANGE,
WILLAPA HILLS, AND NORTH OR/SOUTH WA CASCADES. WINDS WILL ALSO
INCREASE ON THURSDAY AND TURN MORE SOUTHERLY/SOUTHWESTERLY,
HOWEVER BASED ON THE CURRENTLY LOW TRACK AND STRENGTH, IT DOES
NOT APPEAR LIKELY THAT WINDS WOULD LEAD TO SIGNIFICANT IMPACTS.
CHANCES FOR 24 HOUR MAXIMUM WIND GUSTS OF 45 MPH OR GREATER ON
THURSDAY ARE ONLY AROUND 10-20% ACROSS INTERIOR VALLEYS AND
20-30% ALONG THE COAST. THESE WIND GUSTS COULD COME TO FRUITION
IN OUR AREA IF THE LOW ENDS UP BECOMING STRONGER AND/OR TRACKS
FURTHER NORTH. IF THIS HAPPENS, THEN THERE COULD BE ISOLATED
IMPACTS INCLUDING DOWNED TREES OR POWER LINES, BUT AGAIN IT
APPEARS UNLIKELY. -10
LONG TERM...THURSDAY TO MONDAY
ONCE THE FRONT PUSHES THROUGH
THE AREA WEDNESDAY NIGHT, TEMPERATURES WILL BECOME COOLER ON
THURSDAY. THERE IS A 30-50% CHANCE THAT 850 MB (5000 FT
ELEVATION) TEMPERATURES FALL TO 0 DEG C OR LOWER THURSDAY-
FRIDAY. THIS WOULD POTENTIALLY BRING SNOW LEVELS DOWN TO PASS-
LEVEL IN THE CASCADES. GUIDANCE HAS TRENDED DOWNWARD WHEN IT
COMES TO SNOW AMOUNTS COMPARED TO PREVIOUS FORECAST PACKAGES DUE
TO TEMPERATURES TRENDING SLIGHTLY WARMER. THERE IS NOW A 30-40%
CHANCE THAT 48-HOUR SNOW TOTALS BETWEEN 4 AM THURSDAY TO 4 AM
SATURDAY EXCEEDS 6 INCHES AT SANTIAM AND WILLAMETTE PASSES,
WHILE CHANCES ARE LOWER AROUND 20-30% AT HIGHWAY 26 NEAR
GOVERNMENT CAMP.
ELSEWHERE, RAIN CONTINUES ON THURSDAY AS LOW PRESSURE REMAINS
OVER THE REGION. THUNDERSTORM CHANCES ON THURSDAY HAVE LOWERED
TO AROUND 5-10% AS CAPE/INSTABILITY IS APPEARING MORE MARGINAL
(50-100 J/KG). AN ISOLATED THUNDERSTORM STILL CAN'T BE RULED
OUT STILL, WHICH COULD PRODUCE LIGHTNING, HEAVY DOWNPOURS,
GUSTY OUTFLOW WINDS, AND/OR SMALL HAIL.
ACTIVE WEATHER CONTINUES FRIDAY THROUGH THE WEEKEND WITH SNOW
LEVELS FORECAST AT PASS-LEVEL THROUGH FRIDAY MORNING. ON
SATURDAY, ANOTHER FRONTAL SYSTEM WILL BRING IN A WARM FRONT
THAT WILL RAISE SNOW LEVELS AND RETURN RAIN IN THE CASCADES.
HOWEVER, IT'LL BE BRIEF AS THE TRAILING COLD FRONT WILL PUSH
THROUGH SUNDAY AND BRING SNOW LEVELS BACK-DOWN TO PASS-LEVEL
HEADING INTO EARLY NEXT WEEK, RETURNING SNOW CHANCES THROUGH
SANTIAM/WILLAMETTE PASS AND HIGHWAY 26. CHANCES FOR RAIN
CONTINUES EVERYWHERE ELSE THROUGH MONDAY. -10
AVIATION
SATELLITE IMAGERY AND TERMINAL OBSERVATIONS AS OF
EARLY TUESDAY MORNING SHOW A WIDESPREAD MIX OF IFR/MVFR AND LOW-
END VFR CIGS ACROSS THE WILLAMETTE VALLEY AND COAST. HIGH
PRESSURE ALOFT AND A MOIST LOW LEVEL ATMOSPHERE WILL LIKELY
(60-80% CHANCE) MAINTAIN IFR/MVFR CIGS THROUGH 18-21Z TUE. AN
EXCEPTION WOULD BE THE NORTH OREGON COAST (KAST), WHICH HAS
CLEARED UP. IN THIS AREA, COULD SEE SOME LIFR/IFR CONDITIONS DUE
TO FOG OR MIST DEVELOPMENT. LOW STRATUS AND ANY FOG SHOULD CLEAR
OUT BY EARLY AFTERNOON AS MIXING INCREASES DUE TO DAYTIME HEATING.
PREDOMINATELY VFR THRESHOLDS WITH HIGH- LEVEL BKN/OVC CLOUDS
RETURN AFTER 21Z TUE. WINDS WILL GENERALLY BE NORTHERLY TO
NORTHEASTERLY UNDER 5 KT TODAY ACROSS ALL TERMINALS.
KPDX AND APPROACHES...MVFR CIGS WITH OCCASIONAL BREAKS TO LOW-
END VFR THROUGH 18Z TUE. PREDOMINATELY VFR THRESHOLDS RETURN
AFTER 18Z TUE WITH HIGH-LEVEL BKN/OVC CLOUDS. NORTHWESTERLY WINDS
TODAY UNDER 5 KT. -10
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 HAS BEEN ISSUED 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
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 10 AM WEDNESDAY TO 10 AM PST THURSDAY
FOR PZZ210-251>253-271>273.
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