756
FXUS66 KPQR 260551 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
950 PM PST THU DEC 25 2025
..UPDATED AVIATION AND MARINE DISCUSSIONS
SYNOPSIS
WE ARE ENTERING INTO A PERIOD OF TYPICAL WINTER
WEATHER HERE IN THE PACIFIC NORTHWEST WITH A LOW PRESSURE SYSTEM
SITTING OFF OF THE COAST. WILL SEE CONTINUED RAIN AND CASCADE
SNOW THROUGH SATURDAY FOLLOWED BY A RIDGE OF HIGH PRESSURE THAT
WILL KEEP CONDITIONS DRY, COOLER, WITH FOGGY MORNINGS.
SHORT TERM...NOW THROUGH SATURDAY
SATELLITE IMAGERY SHOWS THE
LOW PRESSURE SYSTEM SITTING OFF OF THE COAST THIS AFTERNOON
PUSHING A FRONTAL SYSTEM NORTH OVER THE REGION. THIS FRONT HAS
PRODUCED SOUTHERLY WINDS ALONG THE COAST AND THE WILLAMETTE
VALLEY, AND EASTERLY WINDS THROUGH THE COLUMBIA RIVER GORGE.
RAIN CONTINUES TO FALL WITH VERY MINIMAL ACCUMULATION. RAIN
SHOWERS WILL EASE SLIGHTLY UNTIL FRIDAY MORNING WHEN A SECOND
SHORTWAVE MOVES OVER THE PACIFIC NORTHWEST. AS THIS FRONT MOVES
IN, THE LOW PRESSURE SYSTEM WILL MOVE TOWARDS NORTHERN
CALIFORNIA USHERING IN COOLER AIR AND WESTERLY FLOW TO THE
REGION. THE COMBINATION OF ADDITIONAL PRECIPITATION AND THIS
COOL AIR INFLUX INCREASES THE PROBABILITY FOR SNOW ALONG THE
CASCADES. THERE CONTINUES TO BE HIGHER AND HIGHER CONFIDENCE IN
HIGH-END WINTER WEATHER ADVISORY ACCUMULATIONS WITH THE HIGHEST
AMOUNTS BEING WITHIN SANTIAM AND WILLAMETTE PASS. ONE CHALLENGE
WE WILL FACE WITH THE SNOW IS THE ALIGNMENT OF THE COLD AIR AND
THE PRECIPITATION. IF THE CALIFORNIA LOW ADVECTS NORTHWARD
SLIGHTLY, THE LOBE OF COOLER AIR MAY NOT BE ABLE TO MANIFEST AND
THEREFORE SNOW ACCUMULATION WOULD BE LOWER. BASED ON THE HIGH
RESOLUTION GUIDANCE, THE MEAN FOR SNOW ACCUMULATION IS AROUND
7-9 INCHES WITHIN THE PASSES. HOWEVER THERE IS A 10% CHANCE OF
ACCUMULATIONS UP TO 13 INCHES, AND EQUAL PROBABILITY OF SNOW
ACCUMULATIONS OF 4-6 INCHES.
SNOW WILL BEGIN TO DECREASE LATE INTO SATURDAY MORNING WITH
LINGERING ACTIVITY ENDING IN THE AFTERNOON HOURS. IF YOU PLAN ON
TRAVELING ACROSS THE CASCADES FRIDAY THROUGH SATURDAY MORNING
PREPARE FOR WINTER DRIVING CONDITIONS. -27
LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
HIGH PRESSURE
CONTINUES TO STRENGTHEN THE LATTER HALF OF THE WEEKEND WITH
CLEARER SKIES CAUSING TEMPERATURES TO DROP. OVERNIGHT SATURDAY
INTO SUNDAY, TEMPERATURES WILL FALL AROUND OR BELOW FREEZING FOR
MANY OF THE INLAND VALLEYS. CURRENTLY THERE IS AROUND A 90-95%
CHANCE OF TEMPERATURES BELOW FREEZING WITHIN THE SOUTHERN
WILLAMETTE VALLEY, NEAR 60-70% IN THE NORTHERN WILLAMETTE VALLEY
AND AROUND 15-25% IN THE PORTLAND-VANCOUVER METRO AREA. THE
COAST ALSO HAS A NON-ZERO CHANCE OF SEEING FREEZING TEMPERATURES
SUNDAY MORNING AS WELL. THE PROBABILITY OF 25 DEGREES OR LESS
IS A MUCH LOWER PROBABILITY WITH A 15-25% CHANCE WITHIN THE
SOUTHERN WILLAMETTE VALLEY AND LESS THAN 5% CHANCE ELSEWHERE.
RURAL LOCATIONS IN THE BATTLEGROUND AREA, UPPER HOOD RIVER
VALLEY, ETC WILL HAVE THE HIGHEST PROBABILITY FOR WELL BELOW
FREEZING TEMPERATURES. DURING THE DAY, CONDITIONS WILL BE DRY
AND MOSTLY CLEAR, HOWEVER, WE WILL LIKELY HAVE TO DEAL WITH
PATCHY OVERNIGHT/MORNING FOG WHICH CAN STRUGGLE TO BURN OFF THIS
TIME OF YEAR. SOMETHING TO CONSIDER IS THAT WITH THESE COLD
TEMPERATURES OVERNIGHT AND THE SATURATION THAT IS LIKELY TO
OCCUR, FROST MAY HAVE A HIGHER PROBABILITY OF FORMING VS FOG. IF
TEMPERATURES DROP FASTER THAN SATURATION OCCURS, THEN FROST IS
THE MORE LIKELY SCENARIO. SIMILAR CONDITIONS EXPECTED ON MONDAY
AND TUESDAY MORNINGS BUT MODELS CONTINUE TO BOUNCE BETWEEN A
WARMER OR A COLDER TREND. BASED ON CURRENT GUIDANCE, MONDAY
MORNING APPEARS TO BE THE COLDEST OF THE MORNINGS.
LOOKING INTO THE WAY LONG-TERM, SOME UNCERTAINTY REMAINS
REGARDING THE EXACT BREAKDOWN OF THIS RIDGE FEATURE. NEARLY ALL
OF THE GLOBAL ENSEMBLES SHOW A LONGWAVE TROUGH ALOFT MOVING IN
LATE WEDNESDAY INTO EARLY THURSDAY. -27/99
AVIATION
RADAR IMAGERY AND TERMINAL OBSERVATIONS AS OF LATE
THURSDAY EVENING DEPICTS VFR CONDITIONS WITH ISOLATED SHOWERS ACROSS
NORTHWEST OREGON. AFTER 09-12Z FRI, A LOW PRESSURE SYSTEM OFF THE
COAST OF SOUTHERN OREGON WILL BRING ANOTHER ROUND OF WIDESPREAD
SHOWERS TO THE AREA FROM SOUTH TO NORTH. MODERATE CONFIDENCE (40-
60%) THAT CIGS DROP TO MVFR THRESHOLDS ACROSS THE AREA WITH THIS
SECOND ROUND OF SHOWERS. ON FRIDAY, ANOTHER FRONT WILL MOVE IN FRONT
OF THE NORTHWEST, MAINTAINING SHOWERS AND MVFR CIGS THROUGH THE END
OF THE TAF PERIOD. LIGHT EASTERLY WINDS CONTINUE OVERNIGHT ALONG THE
COAST AND EASTERN PORTLAND METRO TERMINALS. LIGHT AND VARIABLE WINDS
CONTINUE ELSEWHERE. WINDS TURN MORE WEST-SOUTHWESTERLY ON FRIDAY AS
THE NEXT SYSTEM MOVES IN. WINDS ON FRIDAY GENERALLY REMAIN UNDER 10
KT ACROSS THE WILLAMETTE VALLEY, AND 10-15 KT ALONG THE COAST WITH
GUSTS UP TO 20-25 KT IN THE AFTERNOON.
KPDX AND APPROACHES...VFR CONDITIONS UNTIL AROUND 12-14Z FRI, THEN
40-60% CHANCE FOR MVFR CIGS THROUGH THE REST OF THE TAF PERIOD.
MOSTLY DRY UNTIL 09-12Z FRI, THEN RAIN SHOWERS RETURN. EASTERLY
WINDS UNDER 10 KT THROUGH 12Z FRI, THEN GRADUALLY TURNING SOUTH-
SOUTHWESTERLY AFTERWARDS. -10
MARINE
A LOW PRESSURE SYSTEM OFF THE COAST OF SOUTHERN OREGON
CONTINUES TO BRING SOUTH-SOUTHEASTERLY WINDS WITH GUSTS UP TO 25 KT
ACROSS THE WATERS. GALE FORCE CONDITIONS HAVE SUBSIDED; THEREFORE,
THE GALE WARNING ACROSS MARINE ZONES PZZ272-PZZ273 HAS BEEN
DOWNGRADED TO A HAZARDOUS SEAS WARNING THROUGH SATURDAY AFTERNOON.
THE SOUTHERLY SWELL THAT BROUGHT ELEVATED SEAS TODAY WILL GRADUALLY
SUBSIDE, BRIEFLY BRINGING SEAS DOWN TO 10-12 FT AT 11 SEC WITH
SOUTHERLY WIND GUSTS UP TO 20-25 KT TONIGHT.
ANOTHER WEAK FRONT WILL MOVE THROUGH THE WATERS ON FRIDAY, SHIFTING
WINDS MORE NORTHWESTERLY FRIDAY MORNING AND INCREASING IN THE
AFTERNOON WITH GUSTS TO 25-30 KTS. SEAS ALSO BUILD TO 11-15 FT AT 10
SEC. WINDS BEGIN DECREASING SATURDAY MORNING, BUT SEAS REMAIN
ELEVATED THROUGH THE DAY. SEAS DECREASE LATE AFTERNOON BELOW 10 FT.
THE HAZARDOUS SEAS WARNING AND SMALL CRAFT ADVISORY REMAIN IN EFFECT
THROUGH SATURDAY AFTERNOON ACROSS ALL WATERS. A RIDGE OF HIGH
PRESSURE BUILDS OVERHEAD LATE SATURDAY INTO SUNDAY. WINDS DECREASE
TO LESS THAN 15 KTS BY SATURDAY NIGHT AND SEAS SETTLE IN THE 4-6 FT
RANGE, CONTINUING INTO SUNDAY. -10/03
PQR WATCHES/WARNINGS/ADVISORIES
OR...WINTER WEATHER ADVISORY FROM 4 AM FRIDAY TO 4 PM PST SATURDAY
FOR ORZ126>128.
WA...WINTER WEATHER ADVISORY FROM 4 AM FRIDAY TO 4 PM PST SATURDAY
FOR WAZ211.
PZ...SMALL CRAFT ADVISORY UNTIL 3 PM PST SATURDAY FOR PZZ210-251>253.
HAZARDOUS SEAS WARNING UNTIL 3 PM PST SATURDAY FOR PZZ271>273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
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X.COM/NWSPORTLAND
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