225
FXUS66 KPQR 190053
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
453 PM PST THU DEC 18 2025
SYNOPSIS
A STRONG FRONTAL SYSTEM WITH AN ASSOCIATED
ATMOSPHERIC RIVER CONTINUES IMPACTING THE REGION THROUGH TONIGHT.
HIGH CONFIDENCE IN WIDESPREAD MINOR AND MODERATE RIVER FLOODING
WITH INCREASING CONFIDENCE IN MAJOR RIVER FLOODING FOR A FEW
RIVER POINTS. URBAN AND SMALL STREAM FLOODING CONCERNS ARE
INCREASED THROUGH TONIGHT, AS WELL. BREEZY WINDS CONTINUE
THROUGH THIS EVENING. CASCADE SNOW RETURNS EARLY FRIDAY,
CONTINUING INTO SATURDAY MORNING. RAIN PERSISTS THROUGH EARLY
NEXT WEEK WITH CONTINUED RIVER FLOODING THROUGH SATURDAY.
SHORT TERM...THURSDAY AFTERNOON THROUGH SATURDAY
THE
ADVERTISED ATMOSPHERIC RIVER HAS BEEN IMPACTING NW OREGON AND
SW WASHINGTON SINCE THURSDAY MORNING. THE WARM FRONT WITH THIS
WEATHER SYSTEM HAS MOVED EAST OF THE CASCADES, AND THE COLD
FRONT IS APPROACHING THE COAST. MODERATE TO HEAVY RAIN
CONTINUES ACROSS MUCH OF THE AREA WITH MANY RIVERS RISING
RAPIDLY AS RAIN RATES REMAIN ELEVATED. MORE INFORMATION ON THIS
IN THE HYDROLOGY SECTION BELOW. THE BAND OF PRECIPITATION WILL
SLOWLY MOVE SOUTH INTO SOUTHERN OREGON THROUGHOUT THE NIGHT, AS
THE COLD FRONT MOVES THROUGH THE REGION. BY 4-7 AM FRIDAY, THE
FRONT AND ASSOCIATED BAND OF MODERATE TO HEAVY RAIN SHOULD
MAINLY BE SOUTH OF LANE COUNTY. CONDITIONS TURN TO SHOWERS
BEHIND THE FRONT ON FRIDAY, AND WITH 100-300 J/KG OF CAPE
FORECAST BEHIND THE FRONT, THERE WILL BE A BIT OF A CONVECTIVE
ELEMENT. FOR THE MOST PART, NOT EXPECTING WIDESPREAD
THUNDERSTORMS, THOUGH THERE IS A 10-20% CHANCE OF ISOLATED
THUNDERSTORMS WEST OF INTERSTATE 5. THE CONVECTIVE ELEMENT WILL
MAINLY LEND TO SOME STRONGER SHOWERS WITH HEAVY RAIN, SMALL
HAIL, AND BRIEF GUSTY WINDS, THOUGH A FEW LIGHTNING STRIKES
CAN'T BE RULED OUT WEST OF INTERSTATE 5.
ELEVATED WINDS CONTINUE ACROSS THE REGION AS THE COLD FRONT
APPROACHES. GUSTS TO 55-65 MPH HAVE BEEN OBSERVED ALONG THE
COAST AS WELL AS OVER SOME MOUNTAIN PEAKS IN LANE COUNTY. THE
HIGH WIND WARNING WAS EXPANDED TO COVER THE NORTH OREGON AND
SOUTH WASHINGTON COASTS AS WELL AS THE LANE COUNTY CASCADE
FOOTHILLS. GUSTS UP TO 35-45 MPH HAVE BEEN OBSERVED ELSEWHERE,
AND WINDS WILL REMAIN GUSTY THROUGH THIS EVENING. A WIND
ADVISORY FOR MUCH OF THE REGION AND THE HIGH WIND WARNINGS ARE
IN EFFECT UNTIL 7 PM TONIGHT. WINDS WILL BEGIN DECREASING BELOW
ADVISORY CRITERIA (45 MPH) AND WARNING CRITERIA (58 MPH) AFTER 7
PM BUT WILL STILL REMAIN ELEVATED THROUGH THE EVENING HOURS.
HOWEVER, WINDS WILL DECREASE RAPIDLY BEHIND THE FRONTAL PASSAGE
TONIGHT.
AS THE COLD FRONT MOVES THROUGH THE AREA, COLDER AIR WILL
FOLLOW. THIS WILL ALLOW SNOW LEVELS TO DROP IN THE CASCADES TO
AROUND 2000-3500 FEET BY EARLY FRIDAY MORNING. SNOW LEVELS WILL
BE HIGHER AS MOVING SOUTH THROUGH THE CASCADES. WITH SHOWERS
CONTINUING FRIDAY, RAIN IS EXPECTED TO TRANSITION TO SNOW FRIDAY
MORNING AS THE SNOW LEVELS FALL, WITH SNOW CONTINUING INTO
SATURDAY MORNING BEFORE SHOWERS DECREASE. THE HEAVIEST SNOW WILL
BE ABOVE 2500-3000 FEET, EXCEPT FOR ABOVE 4500 FEET IN THE LANE
COUNTY CASCADES, WITH 6-12 INCHES EXPECTED AT PASS LEVEL AND UP
TO 14-16 INCHES ABOVE PASSES. A WINTER WEATHER ADVISORY HAS BEEN
ISSUED FROM 4 AM FRIDAY THROUGH 4 AM SATURDAY FOR THE LANE
COUNTY CASCADES AND THROUGH 10 AM FOR THE REST OF THE NORTH
OREGON AND SOUTH WASHINGTON CASCADES. -03
LONG TERM...SATURDAY THROUGH WEDNESDAY
ON SATURDAY, THE
GENERAL FLOW BECOMES MORE ZONAL, ALLOWING CONDITIONS TO CALM
SOMEWHAT. THE REMNANTS FROM THE ATMOSPHERIC RIVER WILL LINGER
THROUGH SATURDAY WITH SCATTERED SHOWERS PERSISTING THROUGH THE
DAY. ACCUMULATION WILL BE LIGHT AND MORE TYPICAL FOR THIS TIME
OF YEAR. AREAS THAT WILL RECEIVE THE MOST PRECIPITATION WILL BE
ALONG THE COAST AND THE SOUTH WASHINGTON CASCADES WHERE 0.5-0.75
INCH IS POSSIBLE.
BY SUNDAY, ENSEMBLE GUIDANCE INDICATES TROUGHING DEVELOPS IN THE
EASTERN PACIFIC AND WILL CONTINUE THROUGH THE REST OF THE
EXTENDED FORECAST PERIOD WITH MULTIPLE SHORTWAVES LIKELY TO MOVE
ALONG THE FLOW. DETAILS ON EXACT IMPACTS WITH THESE WAVES ARE
UNCERTAIN AT THIS POINT, BUT PRECIPITATION CHANCES CONTINUE EACH
DAY SUNDAY THROUGH WEDNESDAY. THERE IS MORE CONFIDENCE IN A
SURGE OF RENEWED WIDESPREAD RAIN SUNDAY INTO MONDAY, THOUGH
AMOUNTS WILL BE SIGNIFICANTLY LESS THAN WITH PREVIOUS WEATHER
SYSTEMS AS THIS IS NOT AN ATMOSPHERIC RIVER. CURRENT FORECAST
INDICATES AROUND 0.5-0.8 INCHES FOR THE INTERIOR LOWLANDS, 0.9-2
INCHES ALONG THE COAST, COAST RANGE, WILLAPA HILLS, AND OREGON
CASCADES, AND UP TO 2.5 INCHES FOR THE SOUTH WASHINGTON CASCADES
SUNDAY THROUGH MONDAY. NBM INDICATES AROUND A 60-80% CHANCE FOR
AREAS OUTSIDE OF THE INTERIOR LOWLANDS REACH OR EXCEED 1 INCH
OF RAIN IN 48 HOURS ENDING 4 AM TUESDAY. BEYOND TUESDAY,
UNCERTAINTY INCREASES. KEEP AN EYE ON THE FORECAST, ESPECIALLY
THOSE WHO HAVE TRAVEL PLANS AROUND THE HOLIDAY. -03/27
AVIATION
MIXED FLIGHT CONDITIONS ACROSS THE AIR SPACE THROUGH
THE TAF PERIOD. WIDESPREAD RAIN WILL ALSO RESULT IN INTERMITTENT
VISIBILITY REDUCTIONS AS MODERATE TO HEAVY RAIN IS EXPECTED AS AN
ATMOSPHERIC RIVER WILL IMPACT THE REGION THROUGH 12/19 AND 12/20.
A WARM FRONT WILL CONTINUE TO SLOWLY SHIFT SOUTHWARD AND WILL
RESULT IN A WESTERLY WIND SHIFT BEHIND THE FRONT WITH GUSTS UP TO
40 KT FOR INLAND LOCATIONS AND UP TO 50 KT FOR COASTAL LOCATIONS.
A COLD FRONT IS EXPECTED LATE TONIGHT WHICH WILL BRING ABOUT A
MORE SHOWERY PRECIPITATION AND MAINTAIN MIXED FLIGHT CONDITIONS STARTING
AROUND 12Z FRIDAY FOR AREAS NEAR KAST AND SPREAD SOUTHEASTWARD
THROUGH 00Z SATURDAY. EXPECT THIS CHANGE OVER NEAR KPDX AROUND 20Z
FRIDAY AND 00Z SATURDAY FOR KEUG. A 15-30% PROBABILITY FOR
THUNDERSTORMS IS ALSO EXPECTED ACROSS THE AIRSPACE FROM AT LEAST
15Z FRIDAY AND LIKELY THROUGH 06Z SATURDAY. ANY THUNDERSTORMS
COULD PRODUCE LOCALLY GUSTY WINDS AND SMALL HAIL.
KPDX AND APPROACHES...MIXED FLIGHT CONDITIONS PERSIST THROUGH THE
REMAINDER OF THE TAF PERIOD AS WIDESPREAD RAIN, WHICH CAN BE HEAVY
AT TIMES, WILL ALSO RESULT IN INTERMITTENT VISIBILITY REDUCTIONS.
EXPECT A WESTERLY WIND SHIFT AS A WARM FRONT MOVES SOUTHEASTWARD
OVER THE NEXT FEW HOURS WHICH COULD BRING GUSTS UP TO 35 KT NEAR
THE TERMINAL. A COLD FRONT WILL LIKELY MOVE OVER THE TERMINAL
AROUND 20Z FRIDAY AND WILL BRING ABOUT SHOWERY PRECIPITATION.
MIXED FLIGHT CONDITIONS ARE EXPECTED TO PERSIST BEHIND THE COLD
FRONT. A 15-30% PROBABILITY FOR THUNDERSTORMS ALSO RETURNS AROUND
20Z SATURDAY THROUGH 03Z SATURDAY. ANY THUNDERSTORMS COULD
PRODUCE LOCALLY GUSTY WINDS AND SMALL HAIL. /42
MARINE
A COLD FRONT WILL MOVE THROUGH THE WATERS THURSDAY
NIGHT. WEST TO SOUTHWEST WINDS AHEAD OF THE FRONT WILL REMAIN
IN STRONG GALES WITH OCCASIONAL STORM FORCE GUSTS SOUTH OF CAPE
FALCON AS A COASTAL JET DECREASES. AS THE FRONT MOVES THROUGH,
WINDS WILL RAPIDLY DECREASE TO BELOW GALES, WITH GUSTS
BORDERLINE REACHING 20-22 KTS BY 5 AM FRIDAY. A GALE WARNING
REMAINS IN EFFECT FOR ZONES PZZ271, 251, AND 210 AND A STORM
WARNING FOR ZONES PZZ272, 273, 252, AND 253, BOTH THROUGH 10 PM
THURSDAY. WIND DRIVEN WAVES RAISED HIGHER THAN EXPECTED TODAY,
REMAINING AROUND 18-20 FT AT 11 SECONDS AS OF 4 PM THURSDAY.
SEAS WILL FALL THROUGHOUT THE NIGHT TO AROUND 10-12 FT BY EARLY
FRIDAY MORNING. A HAZARDOUS SEAS WARNING REMAINS IN EFFECT FROM
10 PM THURSDAY THROUGH 10 AM FRIDAY, FALLING TO A SMALL CRAFT
ADVISORY FOR SEAS. CONDITIONS REMAIN STEADY THROUGH THE WEEKEND
WITH WESTERLY WIND GUSTS UP TO 21-25 KTS AND SEAS AROUND 8-10
FEET AT 11 SECONDS. -03
HYDROLOGY
TODAY THROUGH FRIDAY WILL BE HEADS-UP DAYS IN
REGARDS TO RIVER FLOODING DUE TO THE ABUNDANT RAINFALL FROM A
STRONG ATMOSPHERIC RIVER. HEAVIEST RAINFALL OCCURS FOR A
RELATIVELY SHORT PERIOD OF TIME THROUGH TONIGHT, MAINLY FOR
LOCATIONS IN NW OREGON. DUE TO ALREADY SATURATED SOILS AND
SWOLLEN RIVERS FROM PREVIOUS RAIN, RIVERS WILL BE MORE PRONE TO
EXPERIENCE FLOODING. AS IS TYPICAL IN ATMOSPHERIC RIVERS, THE
HIGHEST RAINFALL TOTALS ARE LIKELY TO BE OVER AREAS OF TERRAIN
INCLUDING THE COAST RANGE AND CASCADES, WHILE LESSER TOTALS CAN
BE EXPECTED ACROSS INLAND VALLEYS. HIGH RAIN RATES THIS EVENING
WILL PROMOTE URBAN AND SMALL STREAM FLOODING. IT'S IMPORTANT TO
WATCH YOUR SURROUNDINGS AS URBAN FLOODING CAN COME UPON QUICKLY
AND WITHOUT NOTICE.
AS WE ARE NOW IN THE MIDDLE OF THE EVENT, A NUMBER OF RIVER
POINTS HAVE ALREADY REACHED FLOOD STAGE WITH AROUND 20-25 TOTAL
RIVER POINTS FORECAST TO REACH AT LEAST MINOR FLOOD STAGE.
THREE RIVER POINTS ARE FORECAST TO REACH MAJOR FLOOD STAGE AS OF
THE LATE THURSDAY AFTERNOON UPDATE: CLACKAMAS RIVER NEAR
ESTACADA, CLACKAMAS RIVER NEAR OREGON CITY, AND JOHNSON CREEK
NEAR SYCAMORE. EIGHT ADDITIONAL RIVER POINTS ARE NOW FORECAST
TO REACH MODERATE FLOOD STAGE. RIVER FLOODING WILL CONTINUE INTO
AT LEAST FRIDAY, WITH SOME SLOWER RESPONDING LOCATIONS
CONTINUING INTO THE WEEKEND. THESE RIVER FORECASTS REMAIN VERY
SENSITIVE TO RAINFALL FORECASTS, AND INTERESTED PARTIES SHOULD
EXPECT CHANGES AS THE EVENT CONTINUES. THE LATEST RIVER
FORECASTS ACROSS THE REGION CAN BE FOUND AT
WWW.WATER.NOAA.GOV/WFO/PQR.
BEACH HAZARDS
HAVE ISSUED A NEW ROUND OF COASTAL FLOOD
ADVISORIES FROM 10 AM TO 4 PM FRIDAY AS HIGH TIDAL ANOMALIES
COMBINED WITH COASTAL RIVERS RUNNING WELL ABOVE 80% OF FLOOD FLOW
WILL LEAD TO TIDAL OVERFLOW CONCERNS ALONG THE CENTRAL AND NORTH
OREGON COAST DURING THE DAY ON FRIDAY. EXPECT MINOR FLOODING OF LOW
LYING AREAS UP TO 1 FT ABOVE GROUND LEVEL. IMPACTS WILL BE MOST
PRONOUNCED DURING HIGH TIDE BETWEEN ROUGHLY 11 AM AND 1 PM FRIDAY.
OPTED TO LEAVE THE SOUTH WASHINGTON COAST OUT OF THE ADVISORY AS
TIDAL ANOMALIES WILL REMAIN A BIT BELOW THRESHOLD VALUES AT TOKE
POINT. /CB
PQR WATCHES/WARNINGS/ADVISORIES
OR...HIGH WIND WARNING UNTIL 7 PM PST THIS EVENING FOR ORZ101>103-107-
125.
COASTAL FLOOD ADVISORY FROM 10 AM TO 4 PM PST FRIDAY FOR
ORZ101>103.
WIND ADVISORY UNTIL 7 PM PST THIS EVENING FOR ORZ104>106-108>118-
123-124.
WINTER WEATHER ADVISORY FROM 4 AM FRIDAY TO 10 AM PST SATURDAY
FOR ORZ126-127.
WINTER WEATHER ADVISORY FROM 4 AM FRIDAY TO 4 AM PST SATURDAY
FOR ORZ128.
WA...HIGH WIND WARNING UNTIL 7 PM PST THIS EVENING FOR WAZ201.
WIND ADVISORY UNTIL 7 PM PST THIS EVENING FOR WAZ202>208.
WINTER WEATHER ADVISORY FROM 4 AM FRIDAY TO 10 AM PST SATURDAY
FOR WAZ211.
PZ...GALE WARNING UNTIL 10 PM PST THIS EVENING FOR PZZ210-251-271.
HAZARDOUS SEAS WARNING FROM 10 PM THIS EVENING TO 10 AM PST
FRIDAY FOR PZZ210-251>253-271>273.
SMALL CRAFT ADVISORY FROM 10 AM TO 9 PM PST FRIDAY FOR PZZ210-
251>253-271>273.
STORM WARNING UNTIL 10 PM PST THIS EVENING FOR PZZ252-253-272-
273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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