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000
FXUS66 KPQR 200510
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
910 PM PST FRI DEC 19 2014

.SYNOPSIS...MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND WITH
A STRONG WESTERLY FLOW OVER THE PACIFIC RESULTING IN HEAVY RAIN
ACROSS MUCH OF THE REGION...ESPECIALLY MOUNTAINOUS TERRAIN. THERE IS
THE POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO EARLY NEXT
WEEK. LONGER RANGE MODEL OUTPUT IS SUGGESTING A COLDER AIR MASS WILL
SETTLE OVER THE PACIFIC NORTHWEST LATE NEXT WEEK.

&&

.SHORT TERM...SURFACE OBSERVATIONS AND RADAR INDICATED SOME LIGHT
RAIN SCATTERED OVER THE AREA THIS EVENING. MOIST ISENTROPIC LIFT IS
EXPECTED TO PICK UP OVERNIGHT...AND IS SEEN LOWERING IN MODEL PROGS
FROM NEAR THE 300K ISENTROPE DOWN TO 290K AND BELOW AFTER
MIDNIGHT...WHICH SHOULD RESULT IN MOST AREAS SEEING RAIN DEVELOPING
OVERNIGHT. LOW LEVEL PRES GRADIENTS INCREASE RAPIDLY OVERNIGHT AND
INTO SAT MORNING AS A WARM FRONT APPROACHES THE COAST. FLOW IS
INITIALLY OUT OF THE S TO SW SAT MORNING...BUT TURNS TO THE W DURING
THE DAY. SURFACE PRES GRADIENTS IN MODELS CONTINUE TO SUGGEST
STRONGEST WINDS ALONG THE COAST TO RUN FROM LATE TONIGHT THROUGH SAT
MORNING...BUT LIKELY TO BE A LITTLE BELOW HIGH WIND CRITERIA FOR
MOST LOCATIONS. WILL CONTINUE TO MENTION GUSTS TO AROUND 55 MPH
MAINLY FOR THE HEADLANDS AND BEACHES. THE STRONG SW FLOW IN THE
MORNING COUPLED WITH THE ARRIVAL OF THE TROPICAL MOISTURE COMING
ACROSS THE PACIFIC SUGGESTS SOME HEAVY RAINFALL DEVELOPING OVER MUCH
OF THE FORECAST AREA SAT MORNING. AS THE FLOW TURNS MORE WESTERLY AT
850 MB LATER IN THE DAY...OROGRAPHIC EFFECTS WILL ENHANCE WITH
WINDWARD TERRAIN CATCHING THE HEAVIEST RAIN...AND A BIT OF A RAIN
SHADOWING EFFECT BEGINNING TO SHOW TO THE LEEWARD SIDES OF THE
MOUNTAINS. SNOW LEVELS WILL RISE DURING THE DAY SAT WITH WARM AIR
ADVECTION...BUT NOT BEFORE SOME SNOW FALLS IN THE CASCADES. THE SW
FACING CASCADES OF S WA WILL BE THE MOST OROGRAPHICALLY FAVORED IN
THE MORNING WHEN SNOW LEVELS REMAIN LOW...AND SO ARE LIKELY TO SEE
THE MOST SIGNIFICANT SNOWFALL. ON THE COAST...SEAS EXPECTED TO BEGIN
SUBSIDING BY EARLY AFTERNOON WHICH COUPLED WITH SHORTENING WAVE
PERIODS WILL BRING AN AND TO HIGH SURF THREAT.

REMAINDER OF SHORT TERM DISCUSSION UNCHANGED...BOTH GFS AND NAM ARE
TRENDING DOWN WITH QPF ON SUNDAY SO DECREASED IT TO SOME EXTENT...
BUT SINCE THAT LOOKS LIKE WHEN THE BEST OROGRAPHIC ENHANCEMENT WILL
OCCUR...DID NOT WANT TO LIMIT IT TOO MUCH. DID BRING INLAND VALLEY
QPF DOWN A BIT THOUGH TO REFLECT LIKELY STRONG RAIN SHADOW EFFECT
FROM THE COAST RANGE. STILL THINK WE COULD SEE RAIN RATES IN THE
HIGHER ELEVATIONS OF 1.5 TO 2 INCHES PER 6 HRS FOR AS MANY AS 24
HOURS IN A ROW THOUGH. A FEW INCHES OF SNOW FELL TODAY ON MOUNT HOOD
AND PROBABLY SOME OF THE OTHER AREA PEAKS BUT SNOW PACK IS GENERALLY
MINIMAL RIGHT NOW. DESPITE LOW SNOW PACK...LATEST HYDRO GUIDANCE
SUGGESTS SOME RIVERS WILL REACH FLOOD STAGE. PLEASE REFER TO
HYDROLOGY SECTION AND CURRENT FLOOD WATCH FOR MORE DETAILS.

THE ATMOSPHERIC RIVER SPIGOT LOOKS LIKE IT FINALLY SHUTS OFF SUNDAY
NIGHT WITH DECREASING POPS INTO MONDAY AS HIGH PRESSURE PUSHES INTO
THE AREA FROM OFF THE CALIFORNIA COAST. HOWEVER RIVER FLOODING MAY
CONTINUE TO BE A THREAT AS THE SIGNIFICANT WEEKEND PRECIP DRAINS DOWN
FROM THE HIGHER TERRAIN. BOWEN/WISHAAR

&&

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS. MONDAY NIGHT
THROUGH FRIDAY...AN UPPER LEVEL RIDGE WILL AMPLIFY OVER THE REGION
LATE MONDAY INTO TUESDAY. EXTENDED MODELS AGREE ON A WEAK SHORTWAVE
ATTEMPTING TO FLATTEN THE RIDGE TUESDAY MORNING AS AN UPPER LEVEL
TROUGH BEGINS TO DEEPEN IN THE GULF OF ALASKA. CLOUDY AND RAINY
CONDITIONS WILL LINGER INTO THE MIDDLE OF NEXT WEEK AS THIS DIRTY
RIDGE REMAINS OVER THE AREA. THE NEXT MORE SIGNIFICANT SYSTEM
ARRIVES LATE WEDNESDAY AFTERNOON AS THE UPPER LEVEL TROUGH AXIS
BECOMES MORE NEGATIVELY TILTED AND STARTS TO SHIFT INLAND. THIS
MARKS THE NEXT BEST SHOT FOR THE CASCADES TO FINALLY SEE SOME SNOW
ACCUMULATIONS...AS SNOW LEVELS DROP TO 2000-2500 FT THROUGH
CHRISTMAS DAY. HOLIDAY TRAVELERS HEADED OVER THE CASCADE PASSES WILL
CERTAINLY NEED TO MONITOR THE FORECAST. COLDER NORTH FLOW WILL
FOLLOW AND ALLOW TEMPERATURES TO COOL WELL BELOW NORMAL AS
CONDITIONS DRY OUT NEXT FRIDAY. /27

&&

.HYDROLOGY...CONFIDENCE CONTINUES TO INCREASE THAT A SIGNIFICANT
ATMOSPHERIC RIVER TYPE PRECIPITATION EVENT WILL IMPACT SOUTHWEST
WASHINGTON AND NORTHWEST OREGON OVER THE WEEKEND AND INTO EARLY NEXT
WEEK. PRECIPITATION WILL START LATE TONIGHT INTO EARLY SAT AS A WARM
FRONT PUSHES ONSHORE. THE BAROCLINIC ZONE WILL THEN STALL OVER THE
REGION LATER SAT AND REMAIN NEARLY STATIONARY INTO EARLY MON.
SIGNIFICANT SUB-TROPICAL MOISTURE WITH A LONG FETCH THAT STRETCHES
ALL THE WAY TO THE SOUTH CHINA SEA WILL FEED INTO THIS FRONTAL
SYSTEM...BRINGING THE LIKELIHOOD OF VERY LARGE RAINFALL TOTALS
ACROSS THE REGION. LOW AND MID LEVEL WINDS WILL SWITCH FROM
SOUTHERLY TO WESTERLY SAT AFTERNOON. THESE STRONG WESTERLY WINDS
WILL CONTINUE INTO EARLY MON...WHICH WILL CREATE SIGNIFICANT
OROGRAPHIC ENHANCEMENT TO THE PRECIPITATION ALONG THE HIGHER TERRAIN
OF THE COAST RANGE...FOOTHILLS...AND CASCADES. THESE AREAS ARE
EXPECTED TO SEE AROUND 6 TO 12 INCHES OVER RAIN THROUGH EARLY
MON...WITH LOCALIZED AREAS SEEING EVEN HIGHER AMOUNTS IN THE N
OREGON CASCADES. THE LOWER TERRAIN IS FORECASTED TO SEE
LOWER...ALTHOUGH STILL IMPRESSIVE TOTALS. WE EXPECT 4 TO 8 INCHES TO
FALL ALONG THE COAST...AND 2 TO 5 INCHES OVER THE INTERIOR LOWLANDS.

BASED ON THE LATEST FORECAST RAINFALL TOTALS...NUMEROUS AREA RIVERS
ARE NOW PROJECTED TO REACH FLOOD STAGE. A FEW LOCATIONS ARE EVEN
PROJECTED TO REACH MAJOR FLOOD STAGE. A FLOOD WATCH HAS BEEN ISSUED
FOR ALL OF SW WASHINGTON AND NW OREGON STARTING LATE SAT AFTERNOON
AND CONTINUING THROUGH MON. SOME OF THE FASTER RESPONDING RIVERS
DRAINING THE COAST RANGE AND CASCADES COULD REACH FLOOD STAGE AS
EARLY AS SAT EVENING. SLOWER RESPONDING AND MAIN STEM RIVERS WOULD
LIKELY NOT REACH FLOOD UNTIL LATER SUNDAY OR EARLY NEXT WEEK.

IN ADDITION TO THE FLOODING CONCERNS...EXCESSIVE RAINFALL HAS THE
POTENTIAL TO CREATE LANDSLIDES...DEBRIS FLOWS...AND EXCESSIVE RUNOFF
IN THE VICINITY OF RECENT WILDFIRE BURN SCARS. BURN SCARS FROM TWO
LARGE FIRES THIS SUMMER...THE 36 PIT FIRE IN THE CLACKAMAS RIVER
BASIN NEAR ESTACADA AND THE DECEPTION COMPLEX NEAR OAKRIDGE...WILL
BE PARTICULARLY VULNERABLE.

AS IS USUALLY THE CASE WITH THESE ATMOSPHERIC RIVER HEAVY
PRECIPITATION EVENTS...A LOT DEPENDS ON EXACTLY WHERE THE BAND OF
SUBTROPICAL MOISTURE SETS UP. THE FCST MODELS HAVE BEEN CONSISTENTLY
HIGHLIGHTING OUR REGION FOR SOME OF THE MOST SIGNIFICANT IMPACTS FOR
THE LAST SEVERAL DAYS. HOWEVER...THERE COULD STILL BE SHIFTS IN THE
EXACT POSITIONING OF THE SYSTEM...WHICH WOULD EFFECT PRECIPITATION
ESTIMATES AND RIVER FORECASTS. PLEASE CONTINUE TO FOLLOW THE LATEST
FORECASTS. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE).
PYLE

&&

.AVIATION...RAIN BEGINNING TO FILTER INTO THE AREA WITH CONDITIONS
SLOWLY LOWERING AS A WARM FRONT APPROACHES THE AREA.  MVFR IS
INCREASING ON THE COAST AND SHOULD BE WIDESPREAD OVERNIGHT WITH
AREAS OF IFR DEVELOPING AND CONTINUING THROUGH SATURDAY IN
MODERATE TO HEAVY RAIN. INLAND AREAS GENERALLY VFR BUT EXPECT
CONDITIONS TO HEAD TO LOW MVFR AROUND 12Z SAT OR SO WITH THE WARM
FRONT CLOSER TO THE AREA. MODERATE TO HEAVY RAIN AT TIMES WILL
ALSO REDUCE VISIBILITIES TO 1 TO 2 MILES A TIMES. THE WARM FRONT
LIFTS NORTH OF THE AREA MIDDAY SAT BUT CONTINUED RAIN AS THE
FOLLOWING FRONT REMAIN STALLED OVER NW OREGON AND SW WASHINGTON.

KPDX AND APPROACHES...CURRENT VFR CONDITIONS WITH LIGHT RAIN IS
EXPECTED TO YIELD TO LOW MVFR AROUND 12Z SAT AS A WARM FRONT
APPROACHES. IFR CONDITIONS ALSO POSSIBLE ESPECIALLY LATE TONIGHT
AND SAT MORNING. /MH

&&

.MARINE...VARIETY OF MARINE IMPACTS OVER THE NEXT 24 HOURS. LARGER
LONG PERIOD WESTERLY SWELL REACHED BUOY 46089 ABOUT 80 NM OFFSHORE
LATE THIS AFTERNOON AND HAD BEEN FLUCTUATING BETWEEN 16 AND 19 FT
BUT HAS NOW SETTLED AROUND 20 FT. NEAR SHORE BUOYS ARE AROUND 16
FT AND SHOULD CLIMB TO NEAR 20 FT BY MIDNIGHT AND CONTINUE THROUGH
SATURDAY AFTERNOON THEN BEGIN TO SUBSIDE. CURRENT BUOY
OBSERVATIONS COMPARE FAVORABLY TO MODEL OUTPUT SO CONFIDENCE IN
FORECAST IS GOOD.

SOUTHWESTERLY TO WESTERLY WINDS WILL CONTINUE INTO
SUNDAY...KEEPING SEAS WELL IN THE TEENS THROUGH SUNDAY NIGHT. SEAS
MAY TEMPORARILY BOTTOM OUT NEAR 10 FT EARLY NEXT WEEK BEFORE A
WEAK FRONT...AND ACCOMPANYING LARGER WESTERLY SWELL AROUND 15 FT
SLIDES INTO THE WATERS TOWARDS MIDWEEK.

WINDS WITH THE NEXT FRONTAL STORM SYSTEM IS STILL ON TRACK TO
IMPACT THE WATERS LATE TONIGHT AND SATURDAY MORNING. EXPECT WINDS
TO GRADUALLY INCREASE WITH SOLID GALE FORCE WINDS OF 30 TO 35 KT
WITH GUSTS OF 40 KT EXPECTED ACROSS THE WATERS BY SATURDAY
MORNING. 00Z MODEL RUNS A TOUCH WEAKER SO POSSIBILITY OF
WIDESPREAD STORM FORCE WINDS HAS DIMINISHED. THERE MAY BE AN HOUR
OR TWO BETWEEN 4 AM AND 7 AM SAT WHERE A COASTAL JET DEVELOPS AND
PUSH GUSTS UP CLOSER TO 50 KT. ADDITIONAL GUSTS OF 35 KT MAY
LINGER ACROSS THE WATERS INTO SATURDAY EVENING AS ANOTHER WEAK
SURGE OF WINDS ENTERS THE WATERS.

PEOPLE SHOULD AVOID WALKING AND CLIMBING ON JETTIES ALONG THE
OREGON AND WASHINGTON COASTS THROUGH SATURDAY...BUT ESPECIALLY
THIS AFTERNOON AND EVENING. THERE IS CONSIDERABLE CONCERN THAT
SNEAKER WAVES WILL RUN UP MUCH FARTHER UP THE BEACH THAN WAVES
OBSERVED OVER THE PREVIOUS 15 TO 30 MINUTES. UNDER SIMILAR
SCENARIOS...PEOPLE HAVE BEEN KILLED BY BEING SWEPT OFF THEIR FEET
AND DRAGGED OUT TO SEA BY THE RECEDING WATER OR BY THE WATER
DISLODGING STUCK DRIFTWOOD THAT SUBSEQUENTLY ROLES OVER AN
UNSUSPECTING PERSON. PLEASE BE COGNIZANT OF THIS WHEN RECREATING
ON THE BEACHES OF THE OREGON AND WASHINGTON COASTS THROUGH
SATURDAY.

HIGH TIDE NEAR TOKE POINT IS EXPECTED TO FLIRT WITH 11 FT ON
SATURDAY DUE TO A TIDAL ANOMALY NEAR 1 FT. HOWEVER...THE HEAVIEST
RAIN WILL NOT HAVE ARRIVED TO ALLOW THE FLOWS ON THE WILLAPA AND
NASELLE RIVERS TO INCREASE ENOUGH THAT MINOR TIDAL OVERFLOW
FLOODING WILL BE A CONCERN. WHILE THE TIDAL ANOMALY WILL LIKELY BE
SLIGHTLY LESS ON SUNDAY...THE SUBSTANTIAL INCREASE IN RIVER FLOWS
EXPECTED ON THE WILLAPA AND NASELLE RIVERS INCREASE OUR CONCERN ON
MINOR TIDAL OVERFLOW FLOODING OCCURRING AROUND THE TOWNS OF
RAYMOND...NASELLE AND OTHER LOW LYING SPOTS AROUND WILLAPA BAY
WASHINGTON. IN FACT...BY MIDDAY SUNDAY...SEVERAL OREGON COASTAL
RIVERS WILL LIKELY BE NEAR FLOOD STAGE OR EXCEEDING FLOOD STAGE SO
TIDAL OVERFLOW CONCERNS WILL LIKELY ENCOMPASS A LARGER PORTION OF
OUR COASTLINE. DUE TO THE RIVERS REMAINING RELATIVELY HIGH INTO
MONDAY...TIDAL OVERFLOW CONCERNS COULD CERTAINLY LINGER WITH THE
HIGH TIDE MIDDAY MONDAY. EXPECT THESE ISSUES TO BE MOST PREVALENT
BETWEEN 9 AM AND 3 PM ON SUNDAY/MONDAY. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON
     FOR CASCADE FOOTHILLS IN LANE COUNTY-CASCADES IN LANE COUNTY-
     CENTRAL COAST RANGE OF WESTERN OREGON-CENTRAL COLUMBIA
     RIVER GORGE-CENTRAL OREGON COAST-CENTRAL WILLAMETTE VALLEY-
     COAST RANGE OF NORTHWEST OREGON-GREATER PORTLAND METRO AREA-
     LOWER COLUMBIA-NORTH OREGON COAST-NORTHERN OREGON CASCADE
     FOOTHILLS-NORTHERN OREGON CASCADES-SOUTH WILLAMETTE VALLEY-
     UPPER HOOD RIVER VALLEY-WESTERN COLUMBIA RIVER GORGE.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

WA...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON
     FOR CENTRAL COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-I-5
     CORRIDOR IN COWLITZ COUNTY-SOUTH WASHINGTON CASCADE
     FOOTHILLS-SOUTH WASHINGTON CASCADES-SOUTH WASHINGTON COAST-
     WESTERN COLUMBIA RIVER GORGE-WILLAPA HILLS.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR SOUTH
     WASHINGTON COAST.

     WINTER WEATHER ADVISORY UNTIL 1 PM PST SATURDAY FOR SOUTH
     WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 AM PST SATURDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     GALE WARNING FROM 1 AM TO 9 PM PST SATURDAY FOR COASTAL WATERS
     FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 AM PST SATURDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 AM PST
     SUNDAY.

&&


$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 200510
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
910 PM PST FRI DEC 19 2014

.SYNOPSIS...MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND WITH
A STRONG WESTERLY FLOW OVER THE PACIFIC RESULTING IN HEAVY RAIN
ACROSS MUCH OF THE REGION...ESPECIALLY MOUNTAINOUS TERRAIN. THERE IS
THE POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO EARLY NEXT
WEEK. LONGER RANGE MODEL OUTPUT IS SUGGESTING A COLDER AIR MASS WILL
SETTLE OVER THE PACIFIC NORTHWEST LATE NEXT WEEK.

&&

.SHORT TERM...SURFACE OBSERVATIONS AND RADAR INDICATED SOME LIGHT
RAIN SCATTERED OVER THE AREA THIS EVENING. MOIST ISENTROPIC LIFT IS
EXPECTED TO PICK UP OVERNIGHT...AND IS SEEN LOWERING IN MODEL PROGS
FROM NEAR THE 300K ISENTROPE DOWN TO 290K AND BELOW AFTER
MIDNIGHT...WHICH SHOULD RESULT IN MOST AREAS SEEING RAIN DEVELOPING
OVERNIGHT. LOW LEVEL PRES GRADIENTS INCREASE RAPIDLY OVERNIGHT AND
INTO SAT MORNING AS A WARM FRONT APPROACHES THE COAST. FLOW IS
INITIALLY OUT OF THE S TO SW SAT MORNING...BUT TURNS TO THE W DURING
THE DAY. SURFACE PRES GRADIENTS IN MODELS CONTINUE TO SUGGEST
STRONGEST WINDS ALONG THE COAST TO RUN FROM LATE TONIGHT THROUGH SAT
MORNING...BUT LIKELY TO BE A LITTLE BELOW HIGH WIND CRITERIA FOR
MOST LOCATIONS. WILL CONTINUE TO MENTION GUSTS TO AROUND 55 MPH
MAINLY FOR THE HEADLANDS AND BEACHES. THE STRONG SW FLOW IN THE
MORNING COUPLED WITH THE ARRIVAL OF THE TROPICAL MOISTURE COMING
ACROSS THE PACIFIC SUGGESTS SOME HEAVY RAINFALL DEVELOPING OVER MUCH
OF THE FORECAST AREA SAT MORNING. AS THE FLOW TURNS MORE WESTERLY AT
850 MB LATER IN THE DAY...OROGRAPHIC EFFECTS WILL ENHANCE WITH
WINDWARD TERRAIN CATCHING THE HEAVIEST RAIN...AND A BIT OF A RAIN
SHADOWING EFFECT BEGINNING TO SHOW TO THE LEEWARD SIDES OF THE
MOUNTAINS. SNOW LEVELS WILL RISE DURING THE DAY SAT WITH WARM AIR
ADVECTION...BUT NOT BEFORE SOME SNOW FALLS IN THE CASCADES. THE SW
FACING CASCADES OF S WA WILL BE THE MOST OROGRAPHICALLY FAVORED IN
THE MORNING WHEN SNOW LEVELS REMAIN LOW...AND SO ARE LIKELY TO SEE
THE MOST SIGNIFICANT SNOWFALL. ON THE COAST...SEAS EXPECTED TO BEGIN
SUBSIDING BY EARLY AFTERNOON WHICH COUPLED WITH SHORTENING WAVE
PERIODS WILL BRING AN AND TO HIGH SURF THREAT.

REMAINDER OF SHORT TERM DISCUSSION UNCHANGED...BOTH GFS AND NAM ARE
TRENDING DOWN WITH QPF ON SUNDAY SO DECREASED IT TO SOME EXTENT...
BUT SINCE THAT LOOKS LIKE WHEN THE BEST OROGRAPHIC ENHANCEMENT WILL
OCCUR...DID NOT WANT TO LIMIT IT TOO MUCH. DID BRING INLAND VALLEY
QPF DOWN A BIT THOUGH TO REFLECT LIKELY STRONG RAIN SHADOW EFFECT
FROM THE COAST RANGE. STILL THINK WE COULD SEE RAIN RATES IN THE
HIGHER ELEVATIONS OF 1.5 TO 2 INCHES PER 6 HRS FOR AS MANY AS 24
HOURS IN A ROW THOUGH. A FEW INCHES OF SNOW FELL TODAY ON MOUNT HOOD
AND PROBABLY SOME OF THE OTHER AREA PEAKS BUT SNOW PACK IS GENERALLY
MINIMAL RIGHT NOW. DESPITE LOW SNOW PACK...LATEST HYDRO GUIDANCE
SUGGESTS SOME RIVERS WILL REACH FLOOD STAGE. PLEASE REFER TO
HYDROLOGY SECTION AND CURRENT FLOOD WATCH FOR MORE DETAILS.

THE ATMOSPHERIC RIVER SPIGOT LOOKS LIKE IT FINALLY SHUTS OFF SUNDAY
NIGHT WITH DECREASING POPS INTO MONDAY AS HIGH PRESSURE PUSHES INTO
THE AREA FROM OFF THE CALIFORNIA COAST. HOWEVER RIVER FLOODING MAY
CONTINUE TO BE A THREAT AS THE SIGNIFICANT WEEKEND PRECIP DRAINS DOWN
FROM THE HIGHER TERRAIN. BOWEN/WISHAAR

&&

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS. MONDAY NIGHT
THROUGH FRIDAY...AN UPPER LEVEL RIDGE WILL AMPLIFY OVER THE REGION
LATE MONDAY INTO TUESDAY. EXTENDED MODELS AGREE ON A WEAK SHORTWAVE
ATTEMPTING TO FLATTEN THE RIDGE TUESDAY MORNING AS AN UPPER LEVEL
TROUGH BEGINS TO DEEPEN IN THE GULF OF ALASKA. CLOUDY AND RAINY
CONDITIONS WILL LINGER INTO THE MIDDLE OF NEXT WEEK AS THIS DIRTY
RIDGE REMAINS OVER THE AREA. THE NEXT MORE SIGNIFICANT SYSTEM
ARRIVES LATE WEDNESDAY AFTERNOON AS THE UPPER LEVEL TROUGH AXIS
BECOMES MORE NEGATIVELY TILTED AND STARTS TO SHIFT INLAND. THIS
MARKS THE NEXT BEST SHOT FOR THE CASCADES TO FINALLY SEE SOME SNOW
ACCUMULATIONS...AS SNOW LEVELS DROP TO 2000-2500 FT THROUGH
CHRISTMAS DAY. HOLIDAY TRAVELERS HEADED OVER THE CASCADE PASSES WILL
CERTAINLY NEED TO MONITOR THE FORECAST. COLDER NORTH FLOW WILL
FOLLOW AND ALLOW TEMPERATURES TO COOL WELL BELOW NORMAL AS
CONDITIONS DRY OUT NEXT FRIDAY. /27

&&

.HYDROLOGY...CONFIDENCE CONTINUES TO INCREASE THAT A SIGNIFICANT
ATMOSPHERIC RIVER TYPE PRECIPITATION EVENT WILL IMPACT SOUTHWEST
WASHINGTON AND NORTHWEST OREGON OVER THE WEEKEND AND INTO EARLY NEXT
WEEK. PRECIPITATION WILL START LATE TONIGHT INTO EARLY SAT AS A WARM
FRONT PUSHES ONSHORE. THE BAROCLINIC ZONE WILL THEN STALL OVER THE
REGION LATER SAT AND REMAIN NEARLY STATIONARY INTO EARLY MON.
SIGNIFICANT SUB-TROPICAL MOISTURE WITH A LONG FETCH THAT STRETCHES
ALL THE WAY TO THE SOUTH CHINA SEA WILL FEED INTO THIS FRONTAL
SYSTEM...BRINGING THE LIKELIHOOD OF VERY LARGE RAINFALL TOTALS
ACROSS THE REGION. LOW AND MID LEVEL WINDS WILL SWITCH FROM
SOUTHERLY TO WESTERLY SAT AFTERNOON. THESE STRONG WESTERLY WINDS
WILL CONTINUE INTO EARLY MON...WHICH WILL CREATE SIGNIFICANT
OROGRAPHIC ENHANCEMENT TO THE PRECIPITATION ALONG THE HIGHER TERRAIN
OF THE COAST RANGE...FOOTHILLS...AND CASCADES. THESE AREAS ARE
EXPECTED TO SEE AROUND 6 TO 12 INCHES OVER RAIN THROUGH EARLY
MON...WITH LOCALIZED AREAS SEEING EVEN HIGHER AMOUNTS IN THE N
OREGON CASCADES. THE LOWER TERRAIN IS FORECASTED TO SEE
LOWER...ALTHOUGH STILL IMPRESSIVE TOTALS. WE EXPECT 4 TO 8 INCHES TO
FALL ALONG THE COAST...AND 2 TO 5 INCHES OVER THE INTERIOR LOWLANDS.

BASED ON THE LATEST FORECAST RAINFALL TOTALS...NUMEROUS AREA RIVERS
ARE NOW PROJECTED TO REACH FLOOD STAGE. A FEW LOCATIONS ARE EVEN
PROJECTED TO REACH MAJOR FLOOD STAGE. A FLOOD WATCH HAS BEEN ISSUED
FOR ALL OF SW WASHINGTON AND NW OREGON STARTING LATE SAT AFTERNOON
AND CONTINUING THROUGH MON. SOME OF THE FASTER RESPONDING RIVERS
DRAINING THE COAST RANGE AND CASCADES COULD REACH FLOOD STAGE AS
EARLY AS SAT EVENING. SLOWER RESPONDING AND MAIN STEM RIVERS WOULD
LIKELY NOT REACH FLOOD UNTIL LATER SUNDAY OR EARLY NEXT WEEK.

IN ADDITION TO THE FLOODING CONCERNS...EXCESSIVE RAINFALL HAS THE
POTENTIAL TO CREATE LANDSLIDES...DEBRIS FLOWS...AND EXCESSIVE RUNOFF
IN THE VICINITY OF RECENT WILDFIRE BURN SCARS. BURN SCARS FROM TWO
LARGE FIRES THIS SUMMER...THE 36 PIT FIRE IN THE CLACKAMAS RIVER
BASIN NEAR ESTACADA AND THE DECEPTION COMPLEX NEAR OAKRIDGE...WILL
BE PARTICULARLY VULNERABLE.

AS IS USUALLY THE CASE WITH THESE ATMOSPHERIC RIVER HEAVY
PRECIPITATION EVENTS...A LOT DEPENDS ON EXACTLY WHERE THE BAND OF
SUBTROPICAL MOISTURE SETS UP. THE FCST MODELS HAVE BEEN CONSISTENTLY
HIGHLIGHTING OUR REGION FOR SOME OF THE MOST SIGNIFICANT IMPACTS FOR
THE LAST SEVERAL DAYS. HOWEVER...THERE COULD STILL BE SHIFTS IN THE
EXACT POSITIONING OF THE SYSTEM...WHICH WOULD EFFECT PRECIPITATION
ESTIMATES AND RIVER FORECASTS. PLEASE CONTINUE TO FOLLOW THE LATEST
FORECASTS. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE).
PYLE

&&

.AVIATION...RAIN BEGINNING TO FILTER INTO THE AREA WITH CONDITIONS
SLOWLY LOWERING AS A WARM FRONT APPROACHES THE AREA.  MVFR IS
INCREASING ON THE COAST AND SHOULD BE WIDESPREAD OVERNIGHT WITH
AREAS OF IFR DEVELOPING AND CONTINUING THROUGH SATURDAY IN
MODERATE TO HEAVY RAIN. INLAND AREAS GENERALLY VFR BUT EXPECT
CONDITIONS TO HEAD TO LOW MVFR AROUND 12Z SAT OR SO WITH THE WARM
FRONT CLOSER TO THE AREA. MODERATE TO HEAVY RAIN AT TIMES WILL
ALSO REDUCE VISIBILITIES TO 1 TO 2 MILES A TIMES. THE WARM FRONT
LIFTS NORTH OF THE AREA MIDDAY SAT BUT CONTINUED RAIN AS THE
FOLLOWING FRONT REMAIN STALLED OVER NW OREGON AND SW WASHINGTON.

KPDX AND APPROACHES...CURRENT VFR CONDITIONS WITH LIGHT RAIN IS
EXPECTED TO YIELD TO LOW MVFR AROUND 12Z SAT AS A WARM FRONT
APPROACHES. IFR CONDITIONS ALSO POSSIBLE ESPECIALLY LATE TONIGHT
AND SAT MORNING. /MH

&&

.MARINE...VARIETY OF MARINE IMPACTS OVER THE NEXT 24 HOURS. LARGER
LONG PERIOD WESTERLY SWELL REACHED BUOY 46089 ABOUT 80 NM OFFSHORE
LATE THIS AFTERNOON AND HAD BEEN FLUCTUATING BETWEEN 16 AND 19 FT
BUT HAS NOW SETTLED AROUND 20 FT. NEAR SHORE BUOYS ARE AROUND 16
FT AND SHOULD CLIMB TO NEAR 20 FT BY MIDNIGHT AND CONTINUE THROUGH
SATURDAY AFTERNOON THEN BEGIN TO SUBSIDE. CURRENT BUOY
OBSERVATIONS COMPARE FAVORABLY TO MODEL OUTPUT SO CONFIDENCE IN
FORECAST IS GOOD.

SOUTHWESTERLY TO WESTERLY WINDS WILL CONTINUE INTO
SUNDAY...KEEPING SEAS WELL IN THE TEENS THROUGH SUNDAY NIGHT. SEAS
MAY TEMPORARILY BOTTOM OUT NEAR 10 FT EARLY NEXT WEEK BEFORE A
WEAK FRONT...AND ACCOMPANYING LARGER WESTERLY SWELL AROUND 15 FT
SLIDES INTO THE WATERS TOWARDS MIDWEEK.

WINDS WITH THE NEXT FRONTAL STORM SYSTEM IS STILL ON TRACK TO
IMPACT THE WATERS LATE TONIGHT AND SATURDAY MORNING. EXPECT WINDS
TO GRADUALLY INCREASE WITH SOLID GALE FORCE WINDS OF 30 TO 35 KT
WITH GUSTS OF 40 KT EXPECTED ACROSS THE WATERS BY SATURDAY
MORNING. 00Z MODEL RUNS A TOUCH WEAKER SO POSSIBILITY OF
WIDESPREAD STORM FORCE WINDS HAS DIMINISHED. THERE MAY BE AN HOUR
OR TWO BETWEEN 4 AM AND 7 AM SAT WHERE A COASTAL JET DEVELOPS AND
PUSH GUSTS UP CLOSER TO 50 KT. ADDITIONAL GUSTS OF 35 KT MAY
LINGER ACROSS THE WATERS INTO SATURDAY EVENING AS ANOTHER WEAK
SURGE OF WINDS ENTERS THE WATERS.

PEOPLE SHOULD AVOID WALKING AND CLIMBING ON JETTIES ALONG THE
OREGON AND WASHINGTON COASTS THROUGH SATURDAY...BUT ESPECIALLY
THIS AFTERNOON AND EVENING. THERE IS CONSIDERABLE CONCERN THAT
SNEAKER WAVES WILL RUN UP MUCH FARTHER UP THE BEACH THAN WAVES
OBSERVED OVER THE PREVIOUS 15 TO 30 MINUTES. UNDER SIMILAR
SCENARIOS...PEOPLE HAVE BEEN KILLED BY BEING SWEPT OFF THEIR FEET
AND DRAGGED OUT TO SEA BY THE RECEDING WATER OR BY THE WATER
DISLODGING STUCK DRIFTWOOD THAT SUBSEQUENTLY ROLES OVER AN
UNSUSPECTING PERSON. PLEASE BE COGNIZANT OF THIS WHEN RECREATING
ON THE BEACHES OF THE OREGON AND WASHINGTON COASTS THROUGH
SATURDAY.

HIGH TIDE NEAR TOKE POINT IS EXPECTED TO FLIRT WITH 11 FT ON
SATURDAY DUE TO A TIDAL ANOMALY NEAR 1 FT. HOWEVER...THE HEAVIEST
RAIN WILL NOT HAVE ARRIVED TO ALLOW THE FLOWS ON THE WILLAPA AND
NASELLE RIVERS TO INCREASE ENOUGH THAT MINOR TIDAL OVERFLOW
FLOODING WILL BE A CONCERN. WHILE THE TIDAL ANOMALY WILL LIKELY BE
SLIGHTLY LESS ON SUNDAY...THE SUBSTANTIAL INCREASE IN RIVER FLOWS
EXPECTED ON THE WILLAPA AND NASELLE RIVERS INCREASE OUR CONCERN ON
MINOR TIDAL OVERFLOW FLOODING OCCURRING AROUND THE TOWNS OF
RAYMOND...NASELLE AND OTHER LOW LYING SPOTS AROUND WILLAPA BAY
WASHINGTON. IN FACT...BY MIDDAY SUNDAY...SEVERAL OREGON COASTAL
RIVERS WILL LIKELY BE NEAR FLOOD STAGE OR EXCEEDING FLOOD STAGE SO
TIDAL OVERFLOW CONCERNS WILL LIKELY ENCOMPASS A LARGER PORTION OF
OUR COASTLINE. DUE TO THE RIVERS REMAINING RELATIVELY HIGH INTO
MONDAY...TIDAL OVERFLOW CONCERNS COULD CERTAINLY LINGER WITH THE
HIGH TIDE MIDDAY MONDAY. EXPECT THESE ISSUES TO BE MOST PREVALENT
BETWEEN 9 AM AND 3 PM ON SUNDAY/MONDAY. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON
     FOR CASCADE FOOTHILLS IN LANE COUNTY-CASCADES IN LANE COUNTY-
     CENTRAL COAST RANGE OF WESTERN OREGON-CENTRAL COLUMBIA
     RIVER GORGE-CENTRAL OREGON COAST-CENTRAL WILLAMETTE VALLEY-
     COAST RANGE OF NORTHWEST OREGON-GREATER PORTLAND METRO AREA-
     LOWER COLUMBIA-NORTH OREGON COAST-NORTHERN OREGON CASCADE
     FOOTHILLS-NORTHERN OREGON CASCADES-SOUTH WILLAMETTE VALLEY-
     UPPER HOOD RIVER VALLEY-WESTERN COLUMBIA RIVER GORGE.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

WA...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON
     FOR CENTRAL COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-I-5
     CORRIDOR IN COWLITZ COUNTY-SOUTH WASHINGTON CASCADE
     FOOTHILLS-SOUTH WASHINGTON CASCADES-SOUTH WASHINGTON COAST-
     WESTERN COLUMBIA RIVER GORGE-WILLAPA HILLS.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR SOUTH
     WASHINGTON COAST.

     WINTER WEATHER ADVISORY UNTIL 1 PM PST SATURDAY FOR SOUTH
     WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 AM PST SATURDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     GALE WARNING FROM 1 AM TO 9 PM PST SATURDAY FOR COASTAL WATERS
     FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 AM PST SATURDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 AM PST
     SUNDAY.

&&


$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.





000
FXUS66 KPQR 192302 CCB
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
252 PM PST FRI DEC 19 2014

.SYNOPSIS...SCATTERED SHOWERS WILL CONTINUE TODAY WITH SNOW SHOWERS
IN THE CASCADES. MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND
WITH AN ATMOSPHERIC RIVER PATTERN RESULTING IN HEAVY RAIN ACROSS MUCH
OF THE REGION...ESPECIALLY MOUNTAINOUS TERRAIN. THERE IS THE
POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO EARLY NEXT WEEK.
LONGER RANGE MODEL OUTPUT IS SUGGESTING A COLDER AIR MASS WILL SETTLE
OVER THE PACIFIC NORTHWEST LATE NEXT WEEK.

&&

.SHORT TERM...THIS AFTERNOON THROUGH MONDAY...SCATTERED SHOWERS
REMAIN THIS AFTERNOON IN THE WAKE OF AN UPPER TROUGH. WE DID SEE ONE
LIGHTNING STRIKE A BIT BEFORE NOON OVER THE COAST RANGE BUT AT THIS
POINT IT LOOKS LIKE THE THUNDER THREAT HAS ENDED AS ANY FORCING FROM
THE TROUGH HAS MOVED WELL EAST OF THE AREA.

WIDESPREAD STRATIFORM RAIN BEGINS TO MOVE INTO THE AREA LATE TONIGHT
WITH THE ONSET OF WHAT CONTINUES TO LOOK LIKE A RATHER IMPRESSIVE
ATMOSPHERIC RIVER EVENT. ALTHOUGH THE GFS CONTINUES TO DELAY THE 850
MB WESTERLY WIND SHIFT UNTIL SATURDAY EVENING...850 MB WINDS OF
AROUND 50 KT SHOULD ENSURE SIGNIFICANT MOISTURE TRANSPORT. BOTH GFS
AND NAM ARE TRENDING DOWN WITH QPF ON SUNDAY SO DECREASED IT TO SOME
EXTENT...BUT SINCE THAT LOOKS LIKE WHEN THE BEST OROGRAPHIC
ENHANCEMENT WILL OCCUR...DID NOT WANT TO LIMIT IT TOO MUCH. DID BRING
INLAND VALLEY QPF DOWN A BIT THOUGH TO REFLECT LIKELY STRONG RAIN
SHADOW EFFECT FROM THE COAST RANGE. STILL THINK WE COULD SEE RAIN
RATES IN THE HIGHER ELEVATIONS OF 1.5 TO 2 INCHES PER 6 HRS FOR AS
MANY AS 24 HOURS IN A ROW THOUGH. A FEW INCHES OF SNOW FELL TODAY ON
MOUNT HOOD AND PROBABLY SOME OF THE OTHER AREA PEAKS BUT SNOW PACK IS
GENERALLY MINIMAL RIGHT NOW. DESPITE LOW SNOW PACK...LATEST HYDRO
GUIDANCE SUGGESTS SOME RIVERS WILL REACH FLOOD STAGE. PLEASE REFER TO
HYDROLOGY SECTION AND CURRENT FLOOD WATCH FOR MORE DETAILS.

HAVE BEEN DEBATING COASTAL WINDS FOR SATURDAY QUITE A BIT WITH NAM
SHOWING BOUNDARY LAYER WINDS RIGHT AROUND 50 KT EARLY SATURDAY
MORNING. HOWEVER THE GFS PEAKS AT 40 TO 45 KT FOR BOUNDARY LAYER
WINDS AND THE ECM IS EVEN LOWER. DECIDED TO NOT ISSUE ANY HIGH WIND
PRODUCTS FOR BEACHES AND HEADLANDS AT THIS POINT AND WILL INSTEAD LET
THE INCOMING SHIFT REASSESS BASED ON NEW MODEL DATA THIS EVENING. IF
HIGH WINDS WERE TO OCCUR...IT LOOKS LIKE THEY WOULD BE SATURDAY
MORNING AND BEACHES AND HEADLANDS COULD GUST UP TO 60 TO 65
MPH...WHICH WOULD MAKE IT A FAIRLY MARGINAL EVENT.

FINALLY...RAPIDLY BUILDING SEAS WILL BRING THE POTENTIAL FOR
DANGEROUS HIGH SURF ALONG THE BEACHES BEGINNING AS EARLY AS LATER
TODAY. COASTAL VISITORS ARE ENCOURAGED TO STAY OUT OF THE SURF ZONE
AS LONG PERIOD SWELLS WILL REACH SHORE AND MAY SURPRISE INDIVIDUALS
WHO ARE UNAWARE. IN ADDITION...LARGE WAVES MAY WASH OVER BEACHES AND
JETTIES WITH LITTLE WARNING. SOME POTENTIAL EXISTS FOR MINOR TIDAL
OVERFLOW SUNDAY AND MONDAY...ESPECIALLY AROUND HIGH TIDES. THIS
THREAT COULD BE ENHANCED BY HIGH FLOWS ON RIVERS IN RESPONSE TO THE
RAINFALL THIS WEEKEND.

THE ATMOSPHERIC RIVER SPIGOT LOOKS LIKE IT FINALLY SHUTS OFF SUNDAY
NIGHT WITH DECREASING POPS INTO MONDAY AS HIGH PRESSURE PUSHES INTO
THE AREA FROM OFF THE CALIFORNIA COAST. HOWEVER RIVER FLOODING MAY
CONTINUE TO BE A THREAT AS THE SIGNIFICANT WEEKEND PRECIP DRAINS DOWN
FROM THE HIGHER TERRAIN. BOWEN/WISHAAR

&&

.LONG TERM...MONDAY NIGHT THROUGH FRIDAY...AN UPPER LEVEL RIDGE WILL
AMPLIFY OVER THE REGION LATE MONDAY INTO TUESDAY. EXTENDED MODELS
AGREE ON A WEAK SHORTWAVE ATTEMPTING TO FLATTEN THE RIDGE TUESDAY
MORNING AS AN UPPER LEVEL TROUGH BEGINS TO DEEPEN IN THE GULF OF
ALASKA. CLOUDY AND RAINY CONDITIONS WILL LINGER INTO THE MIDDLE OF
NEXT WEEK AS THIS DIRTY RIDGE REMAINS OVER THE AREA. THE NEXT MORE
SIGNIFICANT SYSTEM ARRIVES LATE WEDNESDAY AFTERNOON AS THE UPPER
LEVEL TROUGH AXIS BECOMES MORE NEGATIVELY TILTED AND STARTS TO SHIFT
INLAND. THIS MARKS THE NEXT BEST SHOT FOR THE CASCADES TO FINALLY
SEE SOME SNOW ACCUMULATIONS...AS SNOW LEVELS DROP TO 2000-2500 FT
THROUGH CHRISTMAS DAY. HOLIDAY TRAVELERS HEADED OVER THE CASCADE
PASSES WILL CERTAINLY NEED TO MONITOR THE FORECAST. COLDER NORTH
FLOW WILL FOLLOW AND ALLOW TEMPERATURES TO COOL WELL BELOW NORMAL AS
CONDITIONS DRY OUT NEXT FRIDAY. /27

&&

.HYDROLOGY...CONFIDENCE CONTINUES TO INCREASE THAT A SIGNIFICANT
ATMOSPHERIC RIVER TYPE PRECIPITATION EVENT WILL IMPACT SOUTHWEST
WASHINGTON AND NORTHWEST OREGON OVER THE WEEKEND AND INTO EARLY NEXT
WEEK. PRECIPITATION WILL START LATE TONIGHT INTO EARLY SAT AS A WARM
FRONT PUSHES ONSHORE. THE BAROCLINIC ZONE WILL THEN STALL OVER THE
REGION LATER SAT AND REMAIN NEARLY STATIONARY INTO EARLY MON.
SIGNIFICANT SUB-TROPICAL MOISTURE WITH A LONG FETCH THAT STRETCHES
ALL THE WAY TO THE SOUTH CHINA SEA WILL FEED INTO THIS FRONTAL
SYSTEM...BRINGING THE LIKELIHOOD OF VERY LARGE RAINFALL TOTALS
ACROSS THE REGION. LOW AND MID LEVEL WINDS WILL SWITCH FROM
SOUTHERLY TO WESTERLY SAT AFTERNOON. THESE STRONG WESTERLY WINDS
WILL CONTINUE INTO EARLY MON...WHICH WILL CREATE SIGNIFICANT
OROGRAPHIC ENHANCEMENT TO THE PRECIPITATION ALONG THE HIGHER TERRAIN
OF THE COAST RANGE...FOOTHILLS...AND CASCADES. THESE AREAS ARE
EXPECTED TO SEE AROUND 6 TO 12 INCHES OVER RAIN THROUGH EARLY
MON...WITH LOCALIZED AREAS SEEING EVEN HIGHER AMOUNTS IN THE N
OREGON CASCADES. THE LOWER TERRAIN IS FORECASTED TO SEE
LOWER...ALTHOUGH STILL IMPRESSIVE TOTALS. WE EXPECT 4 TO 8 INCHES TO
FALL ALONG THE COAST...AND 2 TO 5 INCHES OVER THE INTERIOR LOWLANDS.

BASED ON THE LATEST FORECAST RAINFALL TOTALS...NUMEROUS AREA RIVERS
ARE NOW PROJECTED TO REACH FLOOD STAGE. A FEW LOCATIONS ARE EVEN
PROJECTED TO REACH MAJOR FLOOD STAGE. A FLOOD WATCH HAS BEEN ISSUED
FOR ALL OF SW WASHINGTON AND NW OREGON STARTING LATE SAT AFTERNOON
AND CONTINUING THROUGH MON. SOME OF THE FASTER RESPONDING RIVERS
DRAINING THE COAST RANGE AND CASCADES COULD REACH FLOOD STAGE AS
EARLY AS SAT EVENING. SLOWER RESPONDING AND MAIN STEM RIVERS WOULD
LIKELY NOT REACH FLOOD UNTIL LATER SUNDAY OR EARLY NEXT WEEK.

IN ADDITION TO THE FLOODING CONCERNS...EXCESSIVE RAINFALL HAS THE
POTENTIAL TO CREATE LANDSLIDES...DEBRIS FLOWS...AND EXCESSIVE RUNOFF
IN THE VICINITY OF RECENT WILDFIRE BURN SCARS. BURN SCARS FROM TWO
LARGE FIRES THIS SUMMER...THE 36 PIT FIRE IN THE CLACKAMAS RIVER
BASIN NEAR ESTACADA AND THE DECEPTION COMPLEX NEAR OAKRIDGE...WILL
BE PARTICULARLY VULNERABLE.

AS IS USUALLY THE CASE WITH THESE ATMOSPHERIC RIVER HEAVY
PRECIPITATION EVENTS...A LOT DEPENDS ON EXACTLY WHERE THE BAND OF
SUBTROPICAL MOISTURE SETS UP. THE FCST MODELS HAVE BEEN CONSISTENTLY
HIGHLIGHTING OUR REGION FOR SOME OF THE MOST SIGNIFICANT IMPACTS FOR
THE LAST SEVERAL DAYS. HOWEVER...THERE COULD STILL BE SHIFTS IN THE
EXACT POSITIONING OF THE SYSTEM...WHICH WOULD EFFECT PRECIPITATION
ESTIMATES AND RIVER FORECASTS. PLEASE CONTINUE TO FOLLOW THE LATEST
FORECASTS. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE).
PYLE

&&

.AVIATION...A SHOWERY AIRMASS WILL LEAD TO PREDOMINANTLY VFR
CONDITIONS THROUGH THIS EVENING. A WARM FRONT SPREADING WIDESPREAD
LIGHT TO MODERATE RAIN INTO THE AREA OVERNIGHT SHOULD RESULT IN
A DETERIORATION OF CONDITIONS AT ALL TAF SITES AFTER 06Z
SATURDAY. EXPECT WIDESPREAD HIGH END IFR TO MVFR CONDITIONS
BETWEEN 09Z AND 18Z SATURDAY ACROSS NORTHWEST OREGON AND SOUTHWEST
WASHINGTON.

KPDX AND APPROACHES...AN UNSTABLE SHOWERY AIRMASS WILL LEAD TO A
MIX OF VFR AND MVFR CONDITIONS THROUGH 06Z SATURDAY. A WARM FRONT
WILL SPREAD STEADY RAIN INTO THE TERMINAL BETWEEN 09Z AND 18Z
SATURDAY. EXPECT FLIGHT CONDITIONS TO SHIFT MORE SOLIDLY INTO THE
MVFR CATEGORY DURING THIS TIME. /NEUMAN


&&

.MARINE...THE MAIN WEATHER STORY IN THE IMMEDIATE SHORT TERM IS THAT
SEAS CURRENTLY IN THE 10 TO 12 FT RANGE WILL NEARLY DOUBLE IN HEIGHT
TODAY...RISING INTO THE 20 TO 23 FT RANGE WITH A DOMINANT PERIOD
NEAR 18 TO 19 SECONDS. ANY SMALL CRAFT VESSELS ARE URGED TO COME
ONSHORE IMMEDIATELY AS HIGHER SEAS ARE BEGINNING TO ARRIVE. BUOY 89
ABOUT 70 MILES OFFSHORE JUMPED TO 19 FT AT 19 SECONDS AT 2 PM...AND
WILL LIKELY EXCEED 20 FT IN THE NEXT HOUR OR TWO. THESE HIGHER SEAS
WILL PUSH INTO THE INNER COASTAL WATERS BETWEEN 4 AND 6 PM.

PEOPLE SHOULD AVOID WALKING AND CLIMBING ON JETTIES ALONG THE OREGON
AND WASHINGTON COASTS THROUGH SATURDAY...BUT ESPECIALLY THIS
AFTERNOON AND EVENING. THERE IS CONSIDERABLE CONCERN THAT SNEAKER
WAVES WILL RUN UP MUCH FARTHER UP THE BEACH THAN WAVES OBSERVED OVER
THE PREVIOUS 15 TO 30 MINUTES. UNDER SIMILAR SCENARIOS...PEOPLE HAVE
BEEN KILLED BY BEING SWEPT OFF THEIR FEET AND DRAGGED OUT TO SEA BY
THE RECEDING WATER OR BY THE WATER DISLODGING STUCK DRIFTWOOD THAT
SUBSEQUENTLY ROLES OVER AN UNSUSPECTING PERSON. PLEASE BE COGNIZANT
OF THIS WHEN RECREATING ON THE BEACHES OF THE OREGON AND WASHINGTON
COASTS THROUGH SATURDAY.

THE NEXT FRONTAL STORM SYSTEM IS STILL ON TRACK TO IMPACT THE WATERS
LATE TONIGHT AND SATURDAY MORNING. EXPECT WINDS TO GRADUALLY
INCREASE TODAY AND TONIGHT...WITH SOLID GALE FORCE WINDS OF 30 TO 40
KT WITH GUSTS OF 40 TO 45 KT EXPECTED ACROSS THE WATERS BY SATURDAY
MORNING. THERE IS A CHANCE GUSTS MAY APPROACH 50 KT WITHIN 20 NM OF
THE COAST AS A SHORT LIVED COASTAL JET DEVELOPS...PARTICULARLY ALONG
THE CENTRAL OREGON COAST. THE GALE WARNING FOR THE INNER WATERS MAY
NEED TO BE UPGRADED TO A STORM WARNING...BUT WILL LET SUBSEQUENT
SHIFTS DIGEST ADDITIONAL MODEL RUNS BEFORE MAKING THE CALL.

WHILE THE AFOREMENTIONED LARGE WESTERLY SWELL WILL SLOWLY SUBSIDE
SATURDAY...THIS RENEWED SHOT OF STRONG WINDS ACROSS THE WATERS ON
SATURDAY MORNING...WILL LIKELY KEEP SEAS FLIRTING WITH 20 FT MARK
FOR MUCH OF THE DAYLIGHT HOURS ON SATURDAY. EXPECT THE HIGHEST WINDS
TO TAPER AROUND MIDDAY OR EARLY SATURDAY AFTERNOON...WHICH WILL THEN
ALLOW COMBINED SEAS TO BEGIN SUBSIDING. HOWEVER...ADDITIONAL GUSTS
OF 35 KT MAY LINGER ACROSS THE WATERS INTO SATURDAY EVENING AS
ANOTHER WEAK SURGE OF WINDS ENTERS THE WATERS. THE GALE WARNING FOR
LATE TONIGHT AND SATURDAY MORNING WAS EXTENDED INTO SATURDAY EVENING
TO COVER THIS PERIOD...BUT CONFIDENCE IS CONSIDERABLY LOWER THAT
THESE 35 KT WIND GUSTS WILL OCCUR LATE SATURDAY AFTERNOON AND
EVENING. AGAIN...THE PRIMARY WINDOW OF CONCERN FOR THE HIGHEST WINDS
ACROSS THE WATERS WILL BE SATURDAY MORNING...AND CONFIDENCE IS HIGH
THEY WILL OCCUR.

SOUTHWESTERLY TO WESTERLY WINDS WILL CONTINUE INTO SUNDAY...KEEPING
SEAS WELL IN THE TEENS THROUGH SUNDAY NIGHT. SEAS MAY TEMPORARILY
BOTTOM OUT NEAR 10 FT EARLY NEXT WEEK BEFORE A WEAK FRONT...AND
ACCOMPANYING LARGER WESTERLY SWELL AROUND 15 FT SLIDES INTO THE
WATERS TOWARDS MIDWEEK.

HIGH TIDE NEAR TOKE POINT IS EXPECTED TO FLIRT WITH 11 FT ON
SATURDAY DUE TO A TIDAL ANOMALY NEAR 1 FT. HOWEVER...THE HEAVIEST
RAIN WILL NOT HAVE ARRIVED TO ALLOW THE FLOWS ON THE WILLAPA AND
NASELLE RIVERS TO INCREASE ENOUGH THAT MINOR TIDAL OVERFLOW FLOODING
WILL BE A CONCERN. WHILE THE TIDAL ANOMALY WILL LIKELY BE SLIGHTLY
LESS ON SUNDAY...THE SUBSTANTIAL INCREASE IN RIVER FLOWS EXPECTED ON
THE WILLAPA AND NASELLE RIVERS INCREASE OUR CONCERN ON MINOR TIDAL
OVERFLOW FLOODING OCCURRING AROUND THE TOWNS OF RAYMOND...NASELLE
AND OTHER LOW LYING SPOTS AROUND WILLAPA BAY WASHINGTON. IN
FACT...BY MIDDAY SUNDAY...SEVERAL OREGON COASTAL RIVERS WILL LIKELY
BE NEAR FLOOD STAGE OR EXCEEDING FLOOD STAGE SO COASTAL FLOOD
CONCERNS WILL LIKELY ENCOMPASS MUCH OF THE COAST. DUE TO THE RIVERS
REMAINING HIGH AND HIGH TIDAL CYCLES CONTINUING...THESE TIDAL
OVERFLOW CONCERNS COULD CERTAINLY LINGER INTO MONDAY. EXPECT THESE
ISSUES TO BE MOST PREVALENT BETWEEN 9 AM AND 3 PM ON SUNDAY/MONDAY.
/NEUMAN


&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR

     CASCADE FOOTHILLS IN LANE COUNTY-CASCADES IN LANE COUNTY-
     CENTRAL COAST RANGE OF WESTERN OREGON-CENTRAL COLUMBIA
     RIVER GORGE-CENTRAL OREGON COAST-CENTRAL WILLAMETTE VALLEY-
     COAST RANGE OF NORTHWEST OREGON-GREATER PORTLAND METRO AREA-
     LOWER COLUMBIA-NORTH OREGON COAST-NORTHERN OREGON CASCADE
     FOOTHILLS-NORTHERN OREGON CASCADES-SOUTH WILLAMETTE VALLEY-
     UPPER HOOD RIVER VALLEY-WESTERN COLUMBIA RIVER GORGE.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

WA...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR

     CENTRAL COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-I-5
     CORRIDOR IN COWLITZ COUNTY-SOUTH WASHINGTON CASCADE
     FOOTHILLS-SOUTH WASHINGTON CASCADES-SOUTH WASHINGTON COAST-
     WESTERN COLUMBIA RIVER GORGE-WILLAPA HILLS.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR SOUTH WASHINGTON
     COAST.

     WINTER WEATHER ADVISORY UNTIL 1 PM PST SATURDAY FOR SOUTH
     WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 AM PST SATURDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     GALE WARNING FROM 1 AM TO 9 PM PST SATURDAY FOR COASTAL WATERS
     FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 AM PST SATURDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
     NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST
     SUNDAY.

&&


$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 192257 CCA
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
257 PM PST FRI DEC 19 2014

.SYNOPSIS...SCATTERED SHOWERS WILL CONTINUE TODAY WITH SNOW SHOWERS
IN THE CASCADES. MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND
WITH AN ATMOSPHERIC RIVER PATTERN RESULTING IN HEAVY RAIN ACROSS MUCH
OF THE REGION...ESPECIALLY MOUNTAINOUS TERRAIN. THERE IS THE
POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO EARLY NEXT WEEK.
LONGER RANGE MODEL OUTPUT IS SUGGESTING A COLDER AIR MASS WILL SETTLE
OVER THE PACIFIC NORTHWEST LATE NEXT WEEK.

&&

.SHORT TERM...THIS AFTERNOON THROUGH MONDAY...SCATTERED SHOWERS
REMAIN THIS AFTERNOON IN THE WAKE OF AN UPPER TROUGH. WE DID SEE ONE
LIGHTNING STRIKE A BIT BEFORE NOON OVER THE COAST RANGE BUT AT THIS
POINT IT LOOKS LIKE THE THUNDER THREAT HAS ENDED AS ANY FORCING FROM
THE TROUGH HAS MOVED WELL EAST OF THE AREA.

WIDESPREAD STRATIFORM RAIN BEGINS TO MOVE INTO THE AREA LATE TONIGHT
WITH THE ONSET OF WHAT CONTINUES TO LOOK LIKE A RATHER IMPRESSIVE
ATMOSPHERIC RIVER EVENT. ALTHOUGH THE GFS CONTINUES TO DELAY THE 850
MB WESTERLY WIND SHIFT UNTIL SATURDAY EVENING...850 MB WINDS OF
AROUND 50 KT SHOULD ENSURE SIGNIFICANT MOISTURE TRANSPORT. BOTH GFS
AND NAM ARE TRENDING DOWN WITH QPF ON SUNDAY SO DECREASED IT TO SOME
EXTENT...BUT SINCE THAT LOOKS LIKE WHEN THE BEST OROGRAPHIC
ENHANCEMENT WILL OCCUR...DID NOT WANT TO LIMIT IT TOO MUCH. DID BRING
INLAND VALLEY QPF DOWN A BIT THOUGH TO REFLECT LIKELY STRONG RAIN
SHADOW EFFECT FROM THE COAST RANGE. STILL THINK WE COULD SEE RAIN
RATES IN THE HIGHER ELEVATIONS OF 1.5 TO 2 INCHES PER 6 HRS FOR AS
MANY AS 24 HOURS IN A ROW THOUGH. A FEW INCHES OF SNOW FELL TODAY ON
MOUNT HOOD AND PROBABLY SOME OF THE OTHER AREA PEAKS BUT SNOW PACK IS
GENERALLY MINIMAL RIGHT NOW. DESPITE LOW SNOW PACK...LATEST HYDRO
GUIDANCE SUGGESTS SOME RIVERS WILL REACH FLOOD STAGE. PLEASE REFER TO
HYDROLOGY SECTION AND CURRENT FLOOD WATCH FOR MORE DETAILS.

HAVE BEEN DEBATING COASTAL WINDS FOR SATURDAY QUITE A BIT WITH NAM
SHOWING BOUNDARY LAYER WINDS RIGHT AROUND 50 KT EARLY SATURDAY
MORNING. HOWEVER THE GFS PEAKS AT 40 TO 45 KT FOR BOUNDARY LAYER
WINDS AND THE ECM IS EVEN LOWER. DECIDED TO NOT ISSUE ANY HIGH WIND
PRODUCTS FOR BEACHES AND HEADLANDS AT THIS POINT AND WILL INSTEAD LET
THE INCOMING SHIFT REASSESS BASED ON NEW MODEL DATA THIS EVENING. IF
HIGH WINDS WERE TO OCCUR...IT LOOKS LIKE THEY WOULD BE SATURDAY
MORNING AND BEACHES AND HEADLANDS COULD GUST UP TO 60 TO 65
MPH...WHICH WOULD MAKE IT A FAIRLY MARGINAL EVENT.

FINALLY...RAPIDLY BUILDING SEAS WILL BRING THE POTENTIAL FOR
DANGEROUS HIGH SURF ALONG THE BEACHES BEGINNING AS EARLY AS LATER
TODAY. COASTAL VISITORS ARE ENCOURAGED TO STAY OUT OF THE SURF ZONE
AS LONG PERIOD SWELLS WILL REACH SHORE AND MAY SURPRISE INDIVIDUALS
WHO ARE UNAWARE. IN ADDITION...LARGE WAVES MAY WASH OVER BEACHES AND
JETTIES WITH LITTLE WARNING. SOME POTENTIAL EXISTS FOR MINOR TIDAL
OVERFLOW SUNDAY AND MONDAY...ESPECIALLY AROUND HIGH TIDES. THIS
THREAT COULD BE ENHANCED BY HIGH FLOWS ON RIVERS IN RESPONSE TO THE
RAINFALL THIS WEEKEND.

THE ATMOSPHERIC RIVER SPIGOT LOOKS LIKE IT FINALLY SHUTS OFF SUNDAY
NIGHT WITH DECREASING POPS INTO MONDAY AS HIGH PRESSURE PUSHES INTO
THE AREA FROM OFF THE CALIFORNIA COAST. HOWEVER RIVER FLOODING MAY
CONTINUE TO BE A THREAT AS THE SIGNIFICANT WEEKEND PRECIP DRAINS DOWN
FROM THE HIGHER TERRAIN. BOWEN/WEISHAAR

&&

.LONG TERM...MONDAY NIGHT THROUGH FRIDAY...AN UPPER LEVEL RIDGE WILL
AMPLIFY OVER THE REGION LATE MONDAY INTO TUESDAY. EXTENDED MODELS
AGREE ON A WEAK SHORTWAVE ATTEMPTING TO FLATTEN THE RIDGE TUESDAY
MORNING AS AN UPPER LEVEL TROUGH BEGINS TO DEEPEN IN THE GULF OF
ALASKA. CLOUDY AND RAINY CONDITIONS WILL LINGER INTO THE MIDDLE OF
NEXT WEEK AS THIS DIRTY RIDGE REMAINS OVER THE AREA. THE NEXT MORE
SIGNIFICANT SYSTEM ARRIVES LATE WEDNESDAY AFTERNOON AS THE UPPER
LEVEL TROUGH AXIS BECOMES MORE NEGATIVELY TILTED AND STARTS TO SHIFT
INLAND. THIS MARKS THE NEXT BEST SHOT FOR THE CASCADES TO FINALLY
SEE SOME SNOW ACCUMULATIONS...AS SNOW LEVELS DROP TO 2000-2500 FT
THROUGH CHRISTMAS DAY. HOLIDAY TRAVELERS HEADED OVER THE CASCADE
PASSES WILL CERTAINLY NEED TO MONITOR THE FORECAST. COLDER NORTH
FLOW WILL FOLLOW AND ALLOW TEMPERATURES TO COOL WELL BELOW NORMAL AS
CONDITIONS DRY OUT NEXT FRIDAY. /27

&&

.HYDROLOGY...CONFIDENCE CONTINUES TO INCREASE THAT A SIGNIFICANT
ATMOSPHERIC RIVER TYPE PRECIPITATION EVENT WILL IMPACT SOUTHWEST
WASHINGTON AND NORTHWEST OREGON OVER THE WEEKEND AND INTO EARLY NEXT
WEEK. PRECIPITATION WILL START LATE TONIGHT INTO EARLY SAT AS A WARM
FRONT PUSHES ONSHORE. THE BAROCLINIC ZONE WILL THEN STALL OVER THE
REGION LATER SAT AND REMAIN NEARLY STATIONARY INTO EARLY MON.
SIGNIFICANT SUB-TROPICAL MOISTURE WITH A LONG FETCH THAT STRETCHES
ALL THE WAY TO THE SOUTH CHINA SEA WILL FEED INTO THIS FRONTAL
SYSTEM...BRINGING THE LIKELIHOOD OF VERY LARGE RAINFALL TOTALS
ACROSS THE REGION. LOW AND MID LEVEL WINDS WILL SWITCH FROM
SOUTHERLY TO WESTERLY SAT AFTERNOON. THESE STRONG WESTERLY WINDS
WILL CONTINUE INTO EARLY MON...WHICH WILL CREATE SIGNIFICANT
OROGRAPHIC ENHANCEMENT TO THE PRECIPITATION ALONG THE HIGHER TERRAIN
OF THE COAST RANGE...FOOTHILLS...AND CASCADES. THESE AREAS ARE
EXPECTED TO SEE AROUND 6 TO 12 INCHES OF RAIN THROUGH EARLY
MON...WITH LOCALIZED AREAS SEEING EVEN HIGHER AMOUNTS IN THE N
OREGON CASCADES. THE LOWER TERRAIN IS FORECAST TO SEE
LESSER...ALTHOUGH STILL IMPRESSIVE TOTALS. WE EXPECT 4 TO 8 INCHES
TO FALL ALONG THE COAST...AND 2 TO 5 INCHES OVER THE INTERIOR
LOWLANDS.

BASED ON THE LATEST FORECAST RAINFALL TOTALS...NUMEROUS AREA RIVERS
ARE NOW PROJECTED TO REACH FLOOD STAGE. A FEW LOCATIONS ARE EVEN
PROJECTED TO REACH MAJOR FLOOD STAGE. A FLOOD WATCH HAS BEEN ISSUED
FOR ALL OF SW WASHINGTON AND NW OREGON STARTING LATE SAT AFTERNOON
AND CONTINUING THROUGH MON. SOME OF THE FASTER RESPONDING RIVERS
DRAINING THE COAST RANGE AND CASCADES COULD REACH FLOOD STAGE AS
EARLY AS SAT EVENING. SLOWER RESPONDING AND MAIN STEM RIVERS WOULD
LIKELY NOT REACH FLOOD UNTIL LATER SUNDAY OR EARLY NEXT WEEK.

IN ADDITION TO THE FLOODING CONCERNS...EXCESSIVE RAINFALL HAS THE
POTENTIAL TO CREATE LANDSLIDES...DEBRIS FLOWS...AND EXCESSIVE RUNOFF
IN THE VICINITY OF RECENT WILDFIRE BURN SCARS. BURN SCARS FROM TWO
LARGE FIRES THIS SUMMER...THE 36 PIT FIRE IN THE CLACKAMAS RIVER
BASIN NEAR ESTACADA AND THE DECEPTION COMPLEX NEAR OAKRIDGE...WILL
BE PARTICULARLY VULNERABLE.

AS IS USUALLY THE CASE WITH THESE ATMOSPHERIC RIVER HEAVY
PRECIPITATION EVENTS...A LOT DEPENDS ON EXACTLY WHERE THE BAND OF
SUBTROPICAL MOISTURE SETS UP. THE FCST MODELS HAVE BEEN CONSISTENTLY
HIGHLIGHTING OUR REGION FOR SOME OF THE MOST SIGNIFICANT IMPACTS FOR
THE LAST SEVERAL DAYS. HOWEVER...THERE COULD STILL BE SHIFTS IN THE
EXACT POSITIONING OF THE SYSTEM...WHICH WOULD EFFECT PRECIPITATION
ESTIMATES AND RIVER FORECASTS. PLEASE CONTINUE TO FOLLOW THE LATEST
FORECASTS. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE).
PYLE

&&

.AVIATION...A SHOWERY AIRMASS WILL LEAD TO PREDOMINANTLY VFR
CONDITIONS THROUGH THIS EVENING. A WARM FRONT SPREADING WIDESPREAD
LIGHT TO MODERATE RAIN INTO THE AREA OVERNIGHT SHOULD RESULT IN
A DETERIORATION OF CONDITIONS AT ALL TAF SITES AFTER 06Z
SATURDAY. EXPECT WIDESPREAD HIGH END IFR TO MVFR CONDITIONS
BETWEEN 09Z AND 18Z SATURDAY ACROSS NORTHWEST OREGON AND SOUTHWEST
WASHINGTON.

KPDX AND APPROACHES...AN UNSTABLE SHOWERY AIRMASS WILL LEAD TO A
MIX OF VFR AND MVFR CONDITIONS THROUGH 06Z SATURDAY. A WARM FRONT
WILL SPREAD STEADY RAIN INTO THE TERMINAL BETWEEN 09Z AND 18Z
SATURDAY. EXPECT FLIGHT CONDITIONS TO SHIFT MORE SOLIDLY INTO THE
MVFR CATEGORY DURING THIS TIME. /NEUMAN

&&

.MARINE...THE MAIN WEATHER STORY IN THE IMMEDIATE SHORT TERM IS
THAT SEAS CURRENTLY IN THE 10 TO 12 FT RANGE WILL NEARLY DOUBLE IN
HEIGHT TODAY...RISING INTO THE 20 TO 23 FT RANGE WITH A DOMINANT
PERIOD NEAR 18 TO 19 SECONDS. ANY SMALL CRAFT VESSELS ARE URGED
TO COME ONSHORE IMMEDIATELY AS HIGHER SEAS ARE BEGINNING TO
ARRIVE. BUOY 89 ABOUT 70 MILES OFFSHORE JUMPED TO 19 FT AT 19
SECONDS AT 2 PM...AND WILL LIKELY EXCEED 20 FT IN THE NEXT HOUR OR
TWO. THESE HIGHER SEAS WILL PUSH INTO THE INNER COASTAL WATERS
BETWEEN 4 AND 6 PM.

PEOPLE SHOULD AVOID WALKING AND CLIMBING ON JETTIES ALONG THE
OREGON AND WASHINGTON COASTS THROUGH SATURDAY...BUT ESPECIALLY
THIS AFTERNOON AND EVENING. THERE IS CONSIDERABLE CONCERN THAT
SNEAKER WAVES WILL RUN UP MUCH FARTHER UP THE BEACH THAN WAVES
OBSERVED OVER THE PREVIOUS 15 TO 30 MINUTES. UNDER SIMILAR
SCENARIOS...PEOPLE HAVE BEEN KILLED BY BEING SWEPT OFF THEIR FEET
AND DRAGGED OUT TO SEA BY THE RECEDING WATER OR BY THE WATER
DISLODGING STUCK DRIFTWOOD THAT SUBSEQUENTLY ROLES OVER AN
UNSUSPECTING PERSON. PLEASE BE COGNIZANT OF THIS WHEN RECREATING
ON THE BEACHES OF THE OREGON AND WASHINGTON COASTS THROUGH
SATURDAY.

THE NEXT FRONTAL STORM SYSTEM IS STILL ON TRACK TO IMPACT THE
WATERS LATE TONIGHT AND SATURDAY MORNING. EXPECT WINDS TO
GRADUALLY INCREASE TODAY AND TONIGHT...WITH SOLID GALE FORCE WINDS
OF 30 TO 40 KT WITH GUSTS OF 40 TO 45 KT EXPECTED ACROSS THE
WATERS BY SATURDAY MORNING. THERE IS A CHANCE GUSTS MAY APPROACH
50 KT WITHIN 20 NM OF THE COAST AS A SHORT LIVED COASTAL JET
DEVELOPS...PARTICULARLY ALONG THE CENTRAL OREGON COAST. THE GALE
WARNING FOR THE INNER WATERS MAY NEED TO BE UPGRADED TO A STORM
WARNING...BUT WILL LET SUBSEQUENT SHIFTS DIGEST ADDITIONAL MODEL
RUNS BEFORE MAKING THE CALL.

WHILE THE AFOREMENTIONED LARGE WESTERLY SWELL WILL SLOWLY SUBSIDE
SATURDAY...THIS RENEWED SHOT OF STRONG WINDS ACROSS THE
WATERS ON SATURDAY MORNING...WILL LIKELY KEEP SEAS FLIRTING WITH
20 FT MARK FOR MUCH OF THE DAYLIGHT HOURS ON SATURDAY. EXPECT THE
HIGHEST WINDS TO TAPER AROUND MIDDAY OR EARLY SATURDAY
AFTERNOON...WHICH WILL THEN ALLOW COMBINED SEAS TO BEGIN
SUBSIDING. HOWEVER...ADDITIONAL GUSTS OF 35 KT MAY LINGER ACROSS
THE WATERS INTO SATURDAY EVENING AS ANOTHER WEAK SURGE OF WINDS
ENTERS THE WATERS. THE GALE WARNING FOR LATE TONIGHT AND SATURDAY
MORNING WAS EXTENDED INTO SATURDAY EVENING TO COVER THIS
PERIOD...BUT CONFIDENCE IS CONSIDERABLY LOWER THAT THESE 35 KT
WIND GUSTS WILL OCCUR LATE SATURDAY AFTERNOON AND EVENING.
AGAIN...THE PRIMARY WINDOW OF CONCERN FOR THE HIGHEST WINDS ACROSS
THE WATERS WILL BE SATURDAY MORNING...AND CONFIDENCE IS HIGH THEY
WILL OCCUR.

SOUTHWESTERLY TO WESTERLY WINDS WILL CONTINUE INTO SUNDAY...KEEPING
SEAS WELL IN THE TEENS THROUGH SUNDAY NIGHT. SEAS MAY TEMPORARILY
BOTTOM OUT NEAR 10 FT EARLY NEXT WEEK BEFORE A WEAK FRONT...AND
ACCOMPANYING LARGER WESTERLY SWELL AROUND 15 FT SLIDES INTO THE
WATERS TOWARDS MIDWEEK.

HIGH TIDE NEAR TOKE POINT IS EXPECTED TO FLIRT WITH 11 FT ON
SATURDAY DUE TO A TIDAL ANOMALY NEAR 1 FT. HOWEVER...THE HEAVIEST
RAIN WILL NOT HAVE ARRIVED TO ALLOW THE FLOWS ON THE WILLAPA AND
NASELLE RIVERS TO INCREASE ENOUGH THAT MINOR TIDAL OVERFLOW
FLOODING WILL BE A CONCERN. WHILE THE TIDAL ANOMALY WILL LIKELY BE
SLIGHTLY LESS ON SUNDAY...THE SUBSTANTIAL INCREASE IN RIVER FLOWS
EXPECTED ON THE WILLAPA AND NASELLE RIVERS INCREASE OUR CONCERN ON
MINOR TIDAL OVERFLOW FLOODING OCCURRING AROUND THE TOWNS OF
RAYMOND...NASELLE AND OTHER LOW LYING SPOTS AROUND WILLAPA BAY
WASHINGTON. IN FACT...BY MIDDAY SUNDAY...SEVERAL OREGON COASTAL
RIVERS WILL LIKELY BE NEAR FLOOD STAGE OR EXCEEDING FLOOD STAGE SO
COASTAL FLOOD CONCERNS WILL LIKELY ENCOMPASS MUCH OF THE COAST.
DUE TO THE RIVERS REMAINING HIGH AND HIGH TIDAL CYCLES
CONTINUING...THESE TIDAL OVERFLOW CONCERNS COULD CERTAINLY LINGER
INTO MONDAY. EXPECT THESE ISSUES TO BE MOST PREVALENT BETWEEN
9 AM AND 3 PM ON SUNDAY/MONDAY. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR

     CASCADE FOOTHILLS IN LANE COUNTY-CASCADES IN LANE COUNTY-
     CENTRAL COAST RANGE OF WESTERN OREGON-CENTRAL COLUMBIA
     RIVER GORGE-CENTRAL OREGON COAST-CENTRAL WILLAMETTE VALLEY-
     COAST RANGE OF NORTHWEST OREGON-GREATER PORTLAND METRO AREA-
     LOWER COLUMBIA-NORTH OREGON COAST-NORTHERN OREGON CASCADE
     FOOTHILLS-NORTHERN OREGON CASCADES-SOUTH WILLAMETTE VALLEY-
     UPPER HOOD RIVER VALLEY-WESTERN COLUMBIA RIVER GORGE.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

WA...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR

     CENTRAL COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-I-5
     CORRIDOR IN COWLITZ COUNTY-SOUTH WASHINGTON CASCADE
     FOOTHILLS-SOUTH WASHINGTON CASCADES-SOUTH WASHINGTON COAST-
     WESTERN COLUMBIA RIVER GORGE-WILLAPA HILLS.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR SOUTH WASHINGTON
     COAST.

     WINTER WEATHER ADVISORY UNTIL 1 PM PST SATURDAY FOR SOUTH
     WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 AM PST SATURDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     GALE WARNING FROM 1 AM TO 9 PM PST SATURDAY FOR COASTAL WATERS
     FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 AM PST SATURDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
     NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST
     SUNDAY.

&&


$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 192257 CCA
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
257 PM PST FRI DEC 19 2014

.SYNOPSIS...SCATTERED SHOWERS WILL CONTINUE TODAY WITH SNOW SHOWERS
IN THE CASCADES. MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND
WITH AN ATMOSPHERIC RIVER PATTERN RESULTING IN HEAVY RAIN ACROSS MUCH
OF THE REGION...ESPECIALLY MOUNTAINOUS TERRAIN. THERE IS THE
POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO EARLY NEXT WEEK.
LONGER RANGE MODEL OUTPUT IS SUGGESTING A COLDER AIR MASS WILL SETTLE
OVER THE PACIFIC NORTHWEST LATE NEXT WEEK.

&&

.SHORT TERM...THIS AFTERNOON THROUGH MONDAY...SCATTERED SHOWERS
REMAIN THIS AFTERNOON IN THE WAKE OF AN UPPER TROUGH. WE DID SEE ONE
LIGHTNING STRIKE A BIT BEFORE NOON OVER THE COAST RANGE BUT AT THIS
POINT IT LOOKS LIKE THE THUNDER THREAT HAS ENDED AS ANY FORCING FROM
THE TROUGH HAS MOVED WELL EAST OF THE AREA.

WIDESPREAD STRATIFORM RAIN BEGINS TO MOVE INTO THE AREA LATE TONIGHT
WITH THE ONSET OF WHAT CONTINUES TO LOOK LIKE A RATHER IMPRESSIVE
ATMOSPHERIC RIVER EVENT. ALTHOUGH THE GFS CONTINUES TO DELAY THE 850
MB WESTERLY WIND SHIFT UNTIL SATURDAY EVENING...850 MB WINDS OF
AROUND 50 KT SHOULD ENSURE SIGNIFICANT MOISTURE TRANSPORT. BOTH GFS
AND NAM ARE TRENDING DOWN WITH QPF ON SUNDAY SO DECREASED IT TO SOME
EXTENT...BUT SINCE THAT LOOKS LIKE WHEN THE BEST OROGRAPHIC
ENHANCEMENT WILL OCCUR...DID NOT WANT TO LIMIT IT TOO MUCH. DID BRING
INLAND VALLEY QPF DOWN A BIT THOUGH TO REFLECT LIKELY STRONG RAIN
SHADOW EFFECT FROM THE COAST RANGE. STILL THINK WE COULD SEE RAIN
RATES IN THE HIGHER ELEVATIONS OF 1.5 TO 2 INCHES PER 6 HRS FOR AS
MANY AS 24 HOURS IN A ROW THOUGH. A FEW INCHES OF SNOW FELL TODAY ON
MOUNT HOOD AND PROBABLY SOME OF THE OTHER AREA PEAKS BUT SNOW PACK IS
GENERALLY MINIMAL RIGHT NOW. DESPITE LOW SNOW PACK...LATEST HYDRO
GUIDANCE SUGGESTS SOME RIVERS WILL REACH FLOOD STAGE. PLEASE REFER TO
HYDROLOGY SECTION AND CURRENT FLOOD WATCH FOR MORE DETAILS.

HAVE BEEN DEBATING COASTAL WINDS FOR SATURDAY QUITE A BIT WITH NAM
SHOWING BOUNDARY LAYER WINDS RIGHT AROUND 50 KT EARLY SATURDAY
MORNING. HOWEVER THE GFS PEAKS AT 40 TO 45 KT FOR BOUNDARY LAYER
WINDS AND THE ECM IS EVEN LOWER. DECIDED TO NOT ISSUE ANY HIGH WIND
PRODUCTS FOR BEACHES AND HEADLANDS AT THIS POINT AND WILL INSTEAD LET
THE INCOMING SHIFT REASSESS BASED ON NEW MODEL DATA THIS EVENING. IF
HIGH WINDS WERE TO OCCUR...IT LOOKS LIKE THEY WOULD BE SATURDAY
MORNING AND BEACHES AND HEADLANDS COULD GUST UP TO 60 TO 65
MPH...WHICH WOULD MAKE IT A FAIRLY MARGINAL EVENT.

FINALLY...RAPIDLY BUILDING SEAS WILL BRING THE POTENTIAL FOR
DANGEROUS HIGH SURF ALONG THE BEACHES BEGINNING AS EARLY AS LATER
TODAY. COASTAL VISITORS ARE ENCOURAGED TO STAY OUT OF THE SURF ZONE
AS LONG PERIOD SWELLS WILL REACH SHORE AND MAY SURPRISE INDIVIDUALS
WHO ARE UNAWARE. IN ADDITION...LARGE WAVES MAY WASH OVER BEACHES AND
JETTIES WITH LITTLE WARNING. SOME POTENTIAL EXISTS FOR MINOR TIDAL
OVERFLOW SUNDAY AND MONDAY...ESPECIALLY AROUND HIGH TIDES. THIS
THREAT COULD BE ENHANCED BY HIGH FLOWS ON RIVERS IN RESPONSE TO THE
RAINFALL THIS WEEKEND.

THE ATMOSPHERIC RIVER SPIGOT LOOKS LIKE IT FINALLY SHUTS OFF SUNDAY
NIGHT WITH DECREASING POPS INTO MONDAY AS HIGH PRESSURE PUSHES INTO
THE AREA FROM OFF THE CALIFORNIA COAST. HOWEVER RIVER FLOODING MAY
CONTINUE TO BE A THREAT AS THE SIGNIFICANT WEEKEND PRECIP DRAINS DOWN
FROM THE HIGHER TERRAIN. BOWEN/WEISHAAR

&&

.LONG TERM...MONDAY NIGHT THROUGH FRIDAY...AN UPPER LEVEL RIDGE WILL
AMPLIFY OVER THE REGION LATE MONDAY INTO TUESDAY. EXTENDED MODELS
AGREE ON A WEAK SHORTWAVE ATTEMPTING TO FLATTEN THE RIDGE TUESDAY
MORNING AS AN UPPER LEVEL TROUGH BEGINS TO DEEPEN IN THE GULF OF
ALASKA. CLOUDY AND RAINY CONDITIONS WILL LINGER INTO THE MIDDLE OF
NEXT WEEK AS THIS DIRTY RIDGE REMAINS OVER THE AREA. THE NEXT MORE
SIGNIFICANT SYSTEM ARRIVES LATE WEDNESDAY AFTERNOON AS THE UPPER
LEVEL TROUGH AXIS BECOMES MORE NEGATIVELY TILTED AND STARTS TO SHIFT
INLAND. THIS MARKS THE NEXT BEST SHOT FOR THE CASCADES TO FINALLY
SEE SOME SNOW ACCUMULATIONS...AS SNOW LEVELS DROP TO 2000-2500 FT
THROUGH CHRISTMAS DAY. HOLIDAY TRAVELERS HEADED OVER THE CASCADE
PASSES WILL CERTAINLY NEED TO MONITOR THE FORECAST. COLDER NORTH
FLOW WILL FOLLOW AND ALLOW TEMPERATURES TO COOL WELL BELOW NORMAL AS
CONDITIONS DRY OUT NEXT FRIDAY. /27

&&

.HYDROLOGY...CONFIDENCE CONTINUES TO INCREASE THAT A SIGNIFICANT
ATMOSPHERIC RIVER TYPE PRECIPITATION EVENT WILL IMPACT SOUTHWEST
WASHINGTON AND NORTHWEST OREGON OVER THE WEEKEND AND INTO EARLY NEXT
WEEK. PRECIPITATION WILL START LATE TONIGHT INTO EARLY SAT AS A WARM
FRONT PUSHES ONSHORE. THE BAROCLINIC ZONE WILL THEN STALL OVER THE
REGION LATER SAT AND REMAIN NEARLY STATIONARY INTO EARLY MON.
SIGNIFICANT SUB-TROPICAL MOISTURE WITH A LONG FETCH THAT STRETCHES
ALL THE WAY TO THE SOUTH CHINA SEA WILL FEED INTO THIS FRONTAL
SYSTEM...BRINGING THE LIKELIHOOD OF VERY LARGE RAINFALL TOTALS
ACROSS THE REGION. LOW AND MID LEVEL WINDS WILL SWITCH FROM
SOUTHERLY TO WESTERLY SAT AFTERNOON. THESE STRONG WESTERLY WINDS
WILL CONTINUE INTO EARLY MON...WHICH WILL CREATE SIGNIFICANT
OROGRAPHIC ENHANCEMENT TO THE PRECIPITATION ALONG THE HIGHER TERRAIN
OF THE COAST RANGE...FOOTHILLS...AND CASCADES. THESE AREAS ARE
EXPECTED TO SEE AROUND 6 TO 12 INCHES OF RAIN THROUGH EARLY
MON...WITH LOCALIZED AREAS SEEING EVEN HIGHER AMOUNTS IN THE N
OREGON CASCADES. THE LOWER TERRAIN IS FORECAST TO SEE
LESSER...ALTHOUGH STILL IMPRESSIVE TOTALS. WE EXPECT 4 TO 8 INCHES
TO FALL ALONG THE COAST...AND 2 TO 5 INCHES OVER THE INTERIOR
LOWLANDS.

BASED ON THE LATEST FORECAST RAINFALL TOTALS...NUMEROUS AREA RIVERS
ARE NOW PROJECTED TO REACH FLOOD STAGE. A FEW LOCATIONS ARE EVEN
PROJECTED TO REACH MAJOR FLOOD STAGE. A FLOOD WATCH HAS BEEN ISSUED
FOR ALL OF SW WASHINGTON AND NW OREGON STARTING LATE SAT AFTERNOON
AND CONTINUING THROUGH MON. SOME OF THE FASTER RESPONDING RIVERS
DRAINING THE COAST RANGE AND CASCADES COULD REACH FLOOD STAGE AS
EARLY AS SAT EVENING. SLOWER RESPONDING AND MAIN STEM RIVERS WOULD
LIKELY NOT REACH FLOOD UNTIL LATER SUNDAY OR EARLY NEXT WEEK.

IN ADDITION TO THE FLOODING CONCERNS...EXCESSIVE RAINFALL HAS THE
POTENTIAL TO CREATE LANDSLIDES...DEBRIS FLOWS...AND EXCESSIVE RUNOFF
IN THE VICINITY OF RECENT WILDFIRE BURN SCARS. BURN SCARS FROM TWO
LARGE FIRES THIS SUMMER...THE 36 PIT FIRE IN THE CLACKAMAS RIVER
BASIN NEAR ESTACADA AND THE DECEPTION COMPLEX NEAR OAKRIDGE...WILL
BE PARTICULARLY VULNERABLE.

AS IS USUALLY THE CASE WITH THESE ATMOSPHERIC RIVER HEAVY
PRECIPITATION EVENTS...A LOT DEPENDS ON EXACTLY WHERE THE BAND OF
SUBTROPICAL MOISTURE SETS UP. THE FCST MODELS HAVE BEEN CONSISTENTLY
HIGHLIGHTING OUR REGION FOR SOME OF THE MOST SIGNIFICANT IMPACTS FOR
THE LAST SEVERAL DAYS. HOWEVER...THERE COULD STILL BE SHIFTS IN THE
EXACT POSITIONING OF THE SYSTEM...WHICH WOULD EFFECT PRECIPITATION
ESTIMATES AND RIVER FORECASTS. PLEASE CONTINUE TO FOLLOW THE LATEST
FORECASTS. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE).
PYLE

&&

.AVIATION...A SHOWERY AIRMASS WILL LEAD TO PREDOMINANTLY VFR
CONDITIONS THROUGH THIS EVENING. A WARM FRONT SPREADING WIDESPREAD
LIGHT TO MODERATE RAIN INTO THE AREA OVERNIGHT SHOULD RESULT IN
A DETERIORATION OF CONDITIONS AT ALL TAF SITES AFTER 06Z
SATURDAY. EXPECT WIDESPREAD HIGH END IFR TO MVFR CONDITIONS
BETWEEN 09Z AND 18Z SATURDAY ACROSS NORTHWEST OREGON AND SOUTHWEST
WASHINGTON.

KPDX AND APPROACHES...AN UNSTABLE SHOWERY AIRMASS WILL LEAD TO A
MIX OF VFR AND MVFR CONDITIONS THROUGH 06Z SATURDAY. A WARM FRONT
WILL SPREAD STEADY RAIN INTO THE TERMINAL BETWEEN 09Z AND 18Z
SATURDAY. EXPECT FLIGHT CONDITIONS TO SHIFT MORE SOLIDLY INTO THE
MVFR CATEGORY DURING THIS TIME. /NEUMAN

&&

.MARINE...THE MAIN WEATHER STORY IN THE IMMEDIATE SHORT TERM IS
THAT SEAS CURRENTLY IN THE 10 TO 12 FT RANGE WILL NEARLY DOUBLE IN
HEIGHT TODAY...RISING INTO THE 20 TO 23 FT RANGE WITH A DOMINANT
PERIOD NEAR 18 TO 19 SECONDS. ANY SMALL CRAFT VESSELS ARE URGED
TO COME ONSHORE IMMEDIATELY AS HIGHER SEAS ARE BEGINNING TO
ARRIVE. BUOY 89 ABOUT 70 MILES OFFSHORE JUMPED TO 19 FT AT 19
SECONDS AT 2 PM...AND WILL LIKELY EXCEED 20 FT IN THE NEXT HOUR OR
TWO. THESE HIGHER SEAS WILL PUSH INTO THE INNER COASTAL WATERS
BETWEEN 4 AND 6 PM.

PEOPLE SHOULD AVOID WALKING AND CLIMBING ON JETTIES ALONG THE
OREGON AND WASHINGTON COASTS THROUGH SATURDAY...BUT ESPECIALLY
THIS AFTERNOON AND EVENING. THERE IS CONSIDERABLE CONCERN THAT
SNEAKER WAVES WILL RUN UP MUCH FARTHER UP THE BEACH THAN WAVES
OBSERVED OVER THE PREVIOUS 15 TO 30 MINUTES. UNDER SIMILAR
SCENARIOS...PEOPLE HAVE BEEN KILLED BY BEING SWEPT OFF THEIR FEET
AND DRAGGED OUT TO SEA BY THE RECEDING WATER OR BY THE WATER
DISLODGING STUCK DRIFTWOOD THAT SUBSEQUENTLY ROLES OVER AN
UNSUSPECTING PERSON. PLEASE BE COGNIZANT OF THIS WHEN RECREATING
ON THE BEACHES OF THE OREGON AND WASHINGTON COASTS THROUGH
SATURDAY.

THE NEXT FRONTAL STORM SYSTEM IS STILL ON TRACK TO IMPACT THE
WATERS LATE TONIGHT AND SATURDAY MORNING. EXPECT WINDS TO
GRADUALLY INCREASE TODAY AND TONIGHT...WITH SOLID GALE FORCE WINDS
OF 30 TO 40 KT WITH GUSTS OF 40 TO 45 KT EXPECTED ACROSS THE
WATERS BY SATURDAY MORNING. THERE IS A CHANCE GUSTS MAY APPROACH
50 KT WITHIN 20 NM OF THE COAST AS A SHORT LIVED COASTAL JET
DEVELOPS...PARTICULARLY ALONG THE CENTRAL OREGON COAST. THE GALE
WARNING FOR THE INNER WATERS MAY NEED TO BE UPGRADED TO A STORM
WARNING...BUT WILL LET SUBSEQUENT SHIFTS DIGEST ADDITIONAL MODEL
RUNS BEFORE MAKING THE CALL.

WHILE THE AFOREMENTIONED LARGE WESTERLY SWELL WILL SLOWLY SUBSIDE
SATURDAY...THIS RENEWED SHOT OF STRONG WINDS ACROSS THE
WATERS ON SATURDAY MORNING...WILL LIKELY KEEP SEAS FLIRTING WITH
20 FT MARK FOR MUCH OF THE DAYLIGHT HOURS ON SATURDAY. EXPECT THE
HIGHEST WINDS TO TAPER AROUND MIDDAY OR EARLY SATURDAY
AFTERNOON...WHICH WILL THEN ALLOW COMBINED SEAS TO BEGIN
SUBSIDING. HOWEVER...ADDITIONAL GUSTS OF 35 KT MAY LINGER ACROSS
THE WATERS INTO SATURDAY EVENING AS ANOTHER WEAK SURGE OF WINDS
ENTERS THE WATERS. THE GALE WARNING FOR LATE TONIGHT AND SATURDAY
MORNING WAS EXTENDED INTO SATURDAY EVENING TO COVER THIS
PERIOD...BUT CONFIDENCE IS CONSIDERABLY LOWER THAT THESE 35 KT
WIND GUSTS WILL OCCUR LATE SATURDAY AFTERNOON AND EVENING.
AGAIN...THE PRIMARY WINDOW OF CONCERN FOR THE HIGHEST WINDS ACROSS
THE WATERS WILL BE SATURDAY MORNING...AND CONFIDENCE IS HIGH THEY
WILL OCCUR.

SOUTHWESTERLY TO WESTERLY WINDS WILL CONTINUE INTO SUNDAY...KEEPING
SEAS WELL IN THE TEENS THROUGH SUNDAY NIGHT. SEAS MAY TEMPORARILY
BOTTOM OUT NEAR 10 FT EARLY NEXT WEEK BEFORE A WEAK FRONT...AND
ACCOMPANYING LARGER WESTERLY SWELL AROUND 15 FT SLIDES INTO THE
WATERS TOWARDS MIDWEEK.

HIGH TIDE NEAR TOKE POINT IS EXPECTED TO FLIRT WITH 11 FT ON
SATURDAY DUE TO A TIDAL ANOMALY NEAR 1 FT. HOWEVER...THE HEAVIEST
RAIN WILL NOT HAVE ARRIVED TO ALLOW THE FLOWS ON THE WILLAPA AND
NASELLE RIVERS TO INCREASE ENOUGH THAT MINOR TIDAL OVERFLOW
FLOODING WILL BE A CONCERN. WHILE THE TIDAL ANOMALY WILL LIKELY BE
SLIGHTLY LESS ON SUNDAY...THE SUBSTANTIAL INCREASE IN RIVER FLOWS
EXPECTED ON THE WILLAPA AND NASELLE RIVERS INCREASE OUR CONCERN ON
MINOR TIDAL OVERFLOW FLOODING OCCURRING AROUND THE TOWNS OF
RAYMOND...NASELLE AND OTHER LOW LYING SPOTS AROUND WILLAPA BAY
WASHINGTON. IN FACT...BY MIDDAY SUNDAY...SEVERAL OREGON COASTAL
RIVERS WILL LIKELY BE NEAR FLOOD STAGE OR EXCEEDING FLOOD STAGE SO
COASTAL FLOOD CONCERNS WILL LIKELY ENCOMPASS MUCH OF THE COAST.
DUE TO THE RIVERS REMAINING HIGH AND HIGH TIDAL CYCLES
CONTINUING...THESE TIDAL OVERFLOW CONCERNS COULD CERTAINLY LINGER
INTO MONDAY. EXPECT THESE ISSUES TO BE MOST PREVALENT BETWEEN
9 AM AND 3 PM ON SUNDAY/MONDAY. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR

     CASCADE FOOTHILLS IN LANE COUNTY-CASCADES IN LANE COUNTY-
     CENTRAL COAST RANGE OF WESTERN OREGON-CENTRAL COLUMBIA
     RIVER GORGE-CENTRAL OREGON COAST-CENTRAL WILLAMETTE VALLEY-
     COAST RANGE OF NORTHWEST OREGON-GREATER PORTLAND METRO AREA-
     LOWER COLUMBIA-NORTH OREGON COAST-NORTHERN OREGON CASCADE
     FOOTHILLS-NORTHERN OREGON CASCADES-SOUTH WILLAMETTE VALLEY-
     UPPER HOOD RIVER VALLEY-WESTERN COLUMBIA RIVER GORGE.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

WA...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR

     CENTRAL COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-I-5
     CORRIDOR IN COWLITZ COUNTY-SOUTH WASHINGTON CASCADE
     FOOTHILLS-SOUTH WASHINGTON CASCADES-SOUTH WASHINGTON COAST-
     WESTERN COLUMBIA RIVER GORGE-WILLAPA HILLS.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR SOUTH WASHINGTON
     COAST.

     WINTER WEATHER ADVISORY UNTIL 1 PM PST SATURDAY FOR SOUTH
     WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 AM PST SATURDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     GALE WARNING FROM 1 AM TO 9 PM PST SATURDAY FOR COASTAL WATERS
     FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 AM PST SATURDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
     NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST
     SUNDAY.

&&


$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.





000
FXUS66 KPQR 192254 CCA
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
253 PM PST FRI DEC 19 2014

.SYNOPSIS...SCATTERED SHOWERS WILL CONTINUE TODAY WITH SNOW SHOWERS
IN THE CASCADES. MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND
WITH AN ATMOSPHERIC RIVER PATTERN RESULTING IN HEAVY RAIN ACROSS MUCH
OF THE REGION...ESPECIALLY MOUNTAINOUS TERRAIN. THERE IS THE
POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO EARLY NEXT WEEK.
LONGER RANGE MODEL OUTPUT IS SUGGESTING A COLDER AIR MASS WILL SETTLE
OVER THE PACIFIC NORTHWEST LATE NEXT WEEK.

&&

.SHORT TERM...THIS AFTERNOON THROUGH MONDAY...SCATTERED SHOWERS
REMAIN THIS AFTERNOON IN THE WAKE OF AN UPPER TROUGH. WE DID SEE ONE
LIGHTNING STRIKE A BIT BEFORE NOON OVER THE COAST RANGE BUT AT THIS
POINT IT LOOKS LIKE THE THUNDER THREAT HAS ENDED AS ANY FORCING FROM
THE TROUGH HAS MOVED WELL EAST OF THE AREA.

WIDESPREAD STRATIFORM RAIN BEGINS TO MOVE INTO THE AREA LATE TONIGHT
WITH THE ONSET OF WHAT CONTINUES TO LOOK LIKE A RATHER IMPRESSIVE
ATMOSPHERIC RIVER EVENT. ALTHOUGH THE GFS CONTINUES TO DELAY THE 850
MB WESTERLY WIND SHIFT UNTIL SATURDAY EVENING...850 MB WINDS OF
AROUND 50 KT SHOULD ENSURE SIGNIFICANT MOISTURE TRANSPORT. BOTH GFS
AND NAM ARE TRENDING DOWN WITH QPF ON SUNDAY SO DECREASED IT TO SOME
EXTENT...BUT SINCE THAT LOOKS LIKE WHEN THE BEST OROGRAPHIC
ENHANCEMENT WILL OCCUR...DID NOT WANT TO LIMIT IT TOO MUCH. DID BRING
INLAND VALLEY QPF DOWN A BIT THOUGH TO REFLECT LIKELY STRONG RAIN
SHADOW EFFECT FROM THE COAST RANGE. STILL THINK WE COULD SEE RAIN
RATES IN THE HIGHER ELEVATIONS OF 1.5 TO 2 INCHES PER 6 HRS FOR AS
MANY AS 24 HOURS IN A ROW THOUGH. A FEW INCHES OF SNOW FELL TODAY ON
MOUNT HOOD AND PROBABLY SOME OF THE OTHER AREA PEAKS BUT SNOW PACK IS
GENERALLY MINIMAL RIGHT NOW. DESPITE LOW SNOW PACK...LATEST HYDRO
GUIDANCE SUGGESTS SOME RIVERS WILL REACH FLOOD STAGE. PLEASE REFER TO
HYDROLOGY SECTION AND CURRENT FLOOD WATCH FOR MORE DETAILS.

HAVE BEEN DEBATING COASTAL WINDS FOR SATURDAY QUITE A BIT WITH NAM
SHOWING BOUNDARY LAYER WINDS RIGHT AROUND 50 KT EARLY SATURDAY
MORNING. HOWEVER THE GFS PEAKS AT 40 TO 45 KT FOR BOUNDARY LAYER
WINDS AND THE ECM IS EVEN LOWER. DECIDED TO NOT ISSUE ANY HIGH WIND
PRODUCTS FOR BEACHES AND HEADLANDS AT THIS POINT AND WILL INSTEAD LET
THE INCOMING SHIFT REASSESS BASED ON NEW MODEL DATA THIS EVENING. IF
HIGH WINDS WERE TO OCCUR...IT LOOKS LIKE THEY WOULD BE SATURDAY
MORNING AND BEACHES AND HEADLANDS COULD GUST UP TO 60 TO 65
MPH...WHICH WOULD MAKE IT A FAIRLY MARGINAL EVENT.

FINALLY...RAPIDLY BUILDING SEAS WILL BRING THE POTENTIAL FOR
DANGEROUS HIGH SURF ALONG THE BEACHES BEGINNING AS EARLY AS LATER
TODAY. COASTAL VISITORS ARE ENCOURAGED TO STAY OUT OF THE SURF ZONE
AS LONG PERIOD SWELLS WILL REACH SHORE AND MAY SURPRISE INDIVIDUALS
WHO ARE UNAWARE. IN ADDITION...LARGE WAVES MAY WASH OVER BEACHES AND
JETTIES WITH LITTLE WARNING. SOME POTENTIAL EXISTS FOR MINOR TIDAL
OVERFLOW SUNDAY AND MONDAY...ESPECIALLY AROUND HIGH TIDES. THIS
THREAT COULD BE ENHANCED BY HIGH FLOWS ON RIVERS IN RESPONSE TO THE
RAINFALL THIS WEEKEND.

THE ATMOSPHERIC RIVER SPIGOT LOOKS LIKE IT FINALLY SHUTS OFF SUNDAY
NIGHT WITH DECREASING POPS INTO MONDAY AS HIGH PRESSURE PUSHES INTO
THE AREA FROM OFF THE CALIFORNIA COAST. HOWEVER RIVER FLOODING MAY
CONTINUE TO BE A THREAT AS THE SIGNIFICANT WEEKEND PRECIP DRAINS DOWN
FROM THE HIGHER TERRAIN. BOWEN/WEISHAAR

&&

.LONG TERM...MONDAY NIGHT THROUGH FRIDAY...AN UPPER LEVEL RIDGE WILL
AMPLIFY OVER THE REGION LATE MONDAY INTO TUESDAY. EXTENDED MODELS
AGREE ON A WEAK SHORTWAVE ATTEMPTING TO FLATTEN THE RIDGE TUESDAY
MORNING AS AN UPPER LEVEL TROUGH BEGINS TO DEEPEN IN THE GULF OF
ALASKA. CLOUDY AND RAINY CONDITIONS WILL LINGER INTO THE MIDDLE OF
NEXT WEEK AS THIS DIRTY RIDGE REMAINS OVER THE AREA. THE NEXT MORE
SIGNIFICANT SYSTEM ARRIVES LATE WEDNESDAY AFTERNOON AS THE UPPER
LEVEL TROUGH AXIS BECOMES MORE NEGATIVELY TILTED AND STARTS TO SHIFT
INLAND. THIS MARKS THE NEXT BEST SHOT FOR THE CASCADES TO FINALLY
SEE SOME SNOW ACCUMULATIONS...AS SNOW LEVELS DROP TO 2000-2500 FT
THROUGH CHRISTMAS DAY. HOLIDAY TRAVELERS HEADED OVER THE CASCADE
PASSES WILL CERTAINLY NEED TO MONITOR THE FORECAST. COLDER NORTH
FLOW WILL FOLLOW AND ALLOW TEMPERATURES TO COOL WELL BELOW NORMAL AS
CONDITIONS DRY OUT NEXT FRIDAY. /27

&&

.HYDROLOGY...CONFIDENCE CONTINUES TO INCREASE THAT A SIGNIFICANT
ATMOSPHERIC RIVER TYPE PRECIPITATION EVENT WILL IMPACT SOUTHWEST
WASHINGTON AND NORTHWEST OREGON OVER THE WEEKEND AND INTO EARLY NEXT
WEEK. PRECIPITATION WILL START LATE TONIGHT INTO EARLY SAT AS A WARM
FRONT PUSHES ONSHORE. THE BAROCLINIC ZONE WILL THEN STALL OVER THE
REGION LATER SAT AND REMAIN NEARLY STATIONARY INTO EARLY MON.
SIGNIFICANT SUB-TROPICAL MOISTURE WITH A LONG FETCH THAT STRETCHES
ALL THE WAY TO THE SOUTH CHINA SEA WILL FEED INTO THIS FRONTAL
SYSTEM...BRINGING THE LIKELIHOOD OF VERY LARGE RAINFALL TOTALS
ACROSS THE REGION. LOW AND MID LEVEL WINDS WILL SWITCH FROM
SOUTHERLY TO WESTERLY SAT AFTERNOON. THESE STRONG WESTERLY WINDS
WILL CONTINUE INTO EARLY MON...WHICH WILL CREATE SIGNIFICANT
OROGRAPHIC ENHANCEMENT TO THE PRECIPITATION ALONG THE HIGHER TERRAIN
OF THE COAST RANGE...FOOTHILLS...AND CASCADES. THESE AREAS ARE
EXPECTED TO SEE AROUND 6 TO 12 INCHES OVER RAIN THROUGH EARLY
MON...WITH LOCALIZED AREAS SEEING EVEN HIGHER AMOUNTS IN THE N
OREGON CASCADES. THE LOWER TERRAIN IS FORECASTED TO SEE
LOWER...ALTHOUGH STILL IMPRESSIVE TOTALS. WE EXPECT 4 TO 8 INCHES TO
FALL ALONG THE COAST...AND 2 TO 5 INCHES OVER THE INTERIOR LOWLANDS.

BASED ON THE LATEST FORECAST RAINFALL TOTALS...NUMEROUS AREA RIVERS
ARE NOW PROJECTED TO REACH FLOOD STAGE. A FEW LOCATIONS ARE EVEN
PROJECTED TO REACH MAJOR FLOOD STAGE. A FLOOD WATCH HAS BEEN ISSUED
FOR ALL OF SW WASHINGTON AND NW OREGON STARTING LATE SAT AFTERNOON
AND CONTINUING THROUGH MON. SOME OF THE FASTER RESPONDING RIVERS
DRAINING THE COAST RANGE AND CASCADES COULD REACH FLOOD STAGE AS
EARLY AS SAT EVENING. SLOWER RESPONDING AND MAIN STEM RIVERS WOULD
LIKELY NOT REACH FLOOD UNTIL LATER SUNDAY OR EARLY NEXT WEEK.

IN ADDITION TO THE FLOODING CONCERNS...EXCESSIVE RAINFALL HAS THE
POTENTIAL TO CREATE LANDSLIDES...DEBRIS FLOWS...AND EXCESSIVE RUNOFF
IN THE VICINITY OF RECENT WILDFIRE BURN SCARS. BURN SCARS FROM TWO
LARGE FIRES THIS SUMMER...THE 36 PIT FIRE IN THE CLACKAMAS RIVER
BASIN NEAR ESTACADA AND THE DECEPTION COMPLEX NEAR OAKRIDGE...WILL
BE PARTICULARLY VULNERABLE.

AS IS USUALLY THE CASE WITH THESE ATMOSPHERIC RIVER HEAVY
PRECIPITATION EVENTS...A LOT DEPENDS ON EXACTLY WHERE THE BAND OF
SUBTROPICAL MOISTURE SETS UP. THE FCST MODELS HAVE BEEN CONSISTENTLY
HIGHLIGHTING OUR REGION FOR SOME OF THE MOST SIGNIFICANT IMPACTS FOR
THE LAST SEVERAL DAYS. HOWEVER...THERE COULD STILL BE SHIFTS IN THE
EXACT POSITIONING OF THE SYSTEM...WHICH WOULD EFFECT PRECIPITATION
ESTIMATES AND RIVER FORECASTS. PLEASE CONTINUE TO FOLLOW THE LATEST
FORECASTS. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE).
PYLE

&&
&&


.AVIATION...A SHOWERY AIRMASS WILL LEAD TO PREDOMINANTLY VFR
CONDITIONS THROUGH THIS EVENING. A WARM FRONT SPREADING WIDESPREAD
LIGHT TO MODERATE RAIN INTO THE AREA OVERNIGHT SHOULD RESULT IN
A DETERIORATION OF CONDITIONS AT ALL TAF SITES AFTER 06Z
SATURDAY. EXPECT WIDESPREAD HIGH END IFR TO MVFR CONDITIONS
BETWEEN 09Z AND 18Z SATURDAY ACROSS NORTHWEST OREGON AND SOUTHWEST
WASHINGTON.

KPDX AND APPROACHES...AN UNSTABLE SHOWERY AIRMASS WILL LEAD TO A
MIX OF VFR AND MVFR CONDITIONS THROUGH 06Z SATURDAY. A WARM FRONT
WILL SPREAD STEADY RAIN INTO THE TERMINAL BETWEEN 09Z AND 18Z
SATURDAY. EXPECT FLIGHT CONDITIONS TO SHIFT MORE SOLIDLY INTO THE
MVFR CATEGORY DURING THIS TIME. /NEUMAN


&&

.MARINE...THE MAIN WEATHER STORY IN THE IMMEDIATE SHORT TERM IS
THAT SEAS CURRENTLY IN THE 10 TO 12 FT RANGE WILL NEARLY DOUBLE IN
HEIGHT TODAY...RISING INTO THE 20 TO 23 FT RANGE WITH A DOMINANT
PERIOD NEAR 18 TO 19 SECONDS. ANY SMALL CRAFT VESSELS ARE URGED
TO COME ONSHORE IMMEDIATELY AS HIGHER SEAS ARE BEGINNING TO
ARRIVE. BUOY 89 ABOUT 70 MILES OFFSHORE JUMPED TO 19 FT AT 19
SECONDS AT 2 PM...AND WILL LIKELY EXCEED 20 FT IN THE NEXT HOUR OR
TWO. THESE HIGHER SEAS WILL PUSH INTO THE INNER COASTAL WATERS
BETWEEN 4 AND 6 PM.

PEOPLE SHOULD AVOID WALKING AND CLIMBING ON JETTIES ALONG THE
OREGON AND WASHINGTON COASTS THROUGH SATURDAY...BUT ESPECIALLY
THIS AFTERNOON AND EVENING. THERE IS CONSIDERABLE CONCERN THAT
SNEAKER WAVES WILL RUN UP MUCH FARTHER UP THE BEACH THAN WAVES
OBSERVED OVER THE PREVIOUS 15 TO 30 MINUTES. UNDER SIMILAR
SCENARIOS...PEOPLE HAVE BEEN KILLED BY BEING SWEPT OFF THEIR FEET
AND DRAGGED OUT TO SEA BY THE RECEDING WATER OR BY THE WATER
DISLODGING STUCK DRIFTWOOD THAT SUBSEQUENTLY ROLES OVER AN
UNSUSPECTING PERSON. PLEASE BE COGNIZANT OF THIS WHEN RECREATING
ON THE BEACHES OF THE OREGON AND WASHINGTON COASTS THROUGH
SATURDAY.

THE NEXT FRONTAL STORM SYSTEM IS STILL ON TRACK TO IMPACT THE
WATERS LATE TONIGHT AND SATURDAY MORNING. EXPECT WINDS TO
GRADUALLY INCREASE TODAY AND TONIGHT...WITH SOLID GALE FORCE WINDS
OF 30 TO 40 KT WITH GUSTS OF 40 TO 45 KT EXPECTED ACROSS THE
WATERS BY SATURDAY MORNING. THERE IS A CHANCE GUSTS MAY APPROACH
50 KT WITHIN 20 NM OF THE COAST AS A SHORT LIVED COASTAL JET
DEVELOPS...PARTICULARLY ALONG THE CENTRAL OREGON COAST. THE GALE
WARNING FOR THE INNER WATERS MAY NEED TO BE UPGRADED TO A STORM
WARNING...BUT WILL LET SUBSEQUENT SHIFTS DIGEST ADDITIONAL MODEL
RUNS BEFORE MAKING THE CALL.

WHILE THE AFOREMENTIONED LARGE WESTERLY SWELL WILL SLOWLY SUBSIDE
SATURDAY...THIS RENEWED SHOT OF STRONG WINDS ACROSS THE
WATERS ON SATURDAY MORNING...WILL LIKELY KEEP SEAS FLIRTING WITH
20 FT MARK FOR MUCH OF THE DAYLIGHT HOURS ON SATURDAY. EXPECT THE
HIGHEST WINDS TO TAPER AROUND MIDDAY OR EARLY SATURDAY
AFTERNOON...WHICH WILL THEN ALLOW COMBINED SEAS TO BEGIN
SUBSIDING. HOWEVER...ADDITIONAL GUSTS OF 35 KT MAY LINGER ACROSS
THE WATERS INTO SATURDAY EVENING AS ANOTHER WEAK SURGE OF WINDS
ENTERS THE WATERS. THE GALE WARNING FOR LATE TONIGHT AND SATURDAY
MORNING WAS EXTENDED INTO SATURDAY EVENING TO COVER THIS
PERIOD...BUT CONFIDENCE IS CONSIDERABLY LOWER THAT THESE 35 KT
WIND GUSTS WILL OCCUR LATE SATURDAY AFTERNOON AND EVENING.
AGAIN...THE PRIMARY WINDOW OF CONCERN FOR THE HIGHEST WINDS ACROSS
THE WATERS WILL BE SATURDAY MORNING...AND CONFIDENCE IS HIGH THEY
WILL OCCUR.

SOUTHWESTERLY TO WESTERLY WINDS WILL CONTINUE INTO SUNDAY...KEEPING
SEAS WELL IN THE TEENS THROUGH SUNDAY NIGHT. SEAS MAY TEMPORARILY
BOTTOM OUT NEAR 10 FT EARLY NEXT WEEK BEFORE A WEAK FRONT...AND
ACCOMPANYING LARGER WESTERLY SWELL AROUND 15 FT SLIDES INTO THE
WATERS TOWARDS MIDWEEK.

HIGH TIDE NEAR TOKE POINT IS EXPECTED TO FLIRT WITH 11 FT ON
SATURDAY DUE TO A TIDAL ANOMALY NEAR 1 FT. HOWEVER...THE HEAVIEST
RAIN WILL NOT HAVE ARRIVED TO ALLOW THE FLOWS ON THE WILLAPA AND
NASELLE RIVERS TO INCREASE ENOUGH THAT MINOR TIDAL OVERFLOW
FLOODING WILL BE A CONCERN. WHILE THE TIDAL ANOMALY WILL LIKELY BE
SLIGHTLY LESS ON SUNDAY...THE SUBSTANTIAL INCREASE IN RIVER FLOWS
EXPECTED ON THE WILLAPA AND NASELLE RIVERS INCREASE OUR CONCERN ON
MINOR TIDAL OVERFLOW FLOODING OCCURRING AROUND THE TOWNS OF
RAYMOND...NASELLE AND OTHER LOW LYING SPOTS AROUND WILLAPA BAY
WASHINGTON. IN FACT...BY MIDDAY SUNDAY...SEVERAL OREGON COASTAL
RIVERS WILL LIKELY BE NEAR FLOOD STAGE OR EXCEEDING FLOOD STAGE SO
COASTAL FLOOD CONCERNS WILL LIKELY ENCOMPASS MUCH OF THE COAST.
DUE TO THE RIVERS REMAINING HIGH AND HIGH TIDAL CYCLES
CONTINUING...THESE TIDAL OVERFLOW CONCERNS COULD CERTAINLY LINGER
INTO MONDAY. EXPECT THESE ISSUES TO BE MOST PREVALENT BETWEEN
9 AM AND 3 PM ON SUNDAY/MONDAY. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR

     CASCADE FOOTHILLS IN LANE COUNTY-CASCADES IN LANE COUNTY-
     CENTRAL COAST RANGE OF WESTERN OREGON-CENTRAL COLUMBIA
     RIVER GORGE-CENTRAL OREGON COAST-CENTRAL WILLAMETTE VALLEY-
     COAST RANGE OF NORTHWEST OREGON-GREATER PORTLAND METRO AREA-
     LOWER COLUMBIA-NORTH OREGON COAST-NORTHERN OREGON CASCADE
     FOOTHILLS-NORTHERN OREGON CASCADES-SOUTH WILLAMETTE VALLEY-
     UPPER HOOD RIVER VALLEY-WESTERN COLUMBIA RIVER GORGE.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

WA...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR

     CENTRAL COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-I-5
     CORRIDOR IN COWLITZ COUNTY-SOUTH WASHINGTON CASCADE
     FOOTHILLS-SOUTH WASHINGTON CASCADES-SOUTH WASHINGTON COAST-
     WESTERN COLUMBIA RIVER GORGE-WILLAPA HILLS.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR SOUTH WASHINGTON
     COAST.

     WINTER WEATHER ADVISORY UNTIL 1 PM PST SATURDAY FOR SOUTH
     WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 AM PST SATURDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     GALE WARNING FROM 1 AM TO 9 PM PST SATURDAY FOR COASTAL WATERS
FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 AM PST SATURDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST
SUNDAY.

&&


$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 192254 CCA
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
253 PM PST FRI DEC 19 2014

.SYNOPSIS...SCATTERED SHOWERS WILL CONTINUE TODAY WITH SNOW SHOWERS
IN THE CASCADES. MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND
WITH AN ATMOSPHERIC RIVER PATTERN RESULTING IN HEAVY RAIN ACROSS MUCH
OF THE REGION...ESPECIALLY MOUNTAINOUS TERRAIN. THERE IS THE
POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO EARLY NEXT WEEK.
LONGER RANGE MODEL OUTPUT IS SUGGESTING A COLDER AIR MASS WILL SETTLE
OVER THE PACIFIC NORTHWEST LATE NEXT WEEK.

&&

.SHORT TERM...THIS AFTERNOON THROUGH MONDAY...SCATTERED SHOWERS
REMAIN THIS AFTERNOON IN THE WAKE OF AN UPPER TROUGH. WE DID SEE ONE
LIGHTNING STRIKE A BIT BEFORE NOON OVER THE COAST RANGE BUT AT THIS
POINT IT LOOKS LIKE THE THUNDER THREAT HAS ENDED AS ANY FORCING FROM
THE TROUGH HAS MOVED WELL EAST OF THE AREA.

WIDESPREAD STRATIFORM RAIN BEGINS TO MOVE INTO THE AREA LATE TONIGHT
WITH THE ONSET OF WHAT CONTINUES TO LOOK LIKE A RATHER IMPRESSIVE
ATMOSPHERIC RIVER EVENT. ALTHOUGH THE GFS CONTINUES TO DELAY THE 850
MB WESTERLY WIND SHIFT UNTIL SATURDAY EVENING...850 MB WINDS OF
AROUND 50 KT SHOULD ENSURE SIGNIFICANT MOISTURE TRANSPORT. BOTH GFS
AND NAM ARE TRENDING DOWN WITH QPF ON SUNDAY SO DECREASED IT TO SOME
EXTENT...BUT SINCE THAT LOOKS LIKE WHEN THE BEST OROGRAPHIC
ENHANCEMENT WILL OCCUR...DID NOT WANT TO LIMIT IT TOO MUCH. DID BRING
INLAND VALLEY QPF DOWN A BIT THOUGH TO REFLECT LIKELY STRONG RAIN
SHADOW EFFECT FROM THE COAST RANGE. STILL THINK WE COULD SEE RAIN
RATES IN THE HIGHER ELEVATIONS OF 1.5 TO 2 INCHES PER 6 HRS FOR AS
MANY AS 24 HOURS IN A ROW THOUGH. A FEW INCHES OF SNOW FELL TODAY ON
MOUNT HOOD AND PROBABLY SOME OF THE OTHER AREA PEAKS BUT SNOW PACK IS
GENERALLY MINIMAL RIGHT NOW. DESPITE LOW SNOW PACK...LATEST HYDRO
GUIDANCE SUGGESTS SOME RIVERS WILL REACH FLOOD STAGE. PLEASE REFER TO
HYDROLOGY SECTION AND CURRENT FLOOD WATCH FOR MORE DETAILS.

HAVE BEEN DEBATING COASTAL WINDS FOR SATURDAY QUITE A BIT WITH NAM
SHOWING BOUNDARY LAYER WINDS RIGHT AROUND 50 KT EARLY SATURDAY
MORNING. HOWEVER THE GFS PEAKS AT 40 TO 45 KT FOR BOUNDARY LAYER
WINDS AND THE ECM IS EVEN LOWER. DECIDED TO NOT ISSUE ANY HIGH WIND
PRODUCTS FOR BEACHES AND HEADLANDS AT THIS POINT AND WILL INSTEAD LET
THE INCOMING SHIFT REASSESS BASED ON NEW MODEL DATA THIS EVENING. IF
HIGH WINDS WERE TO OCCUR...IT LOOKS LIKE THEY WOULD BE SATURDAY
MORNING AND BEACHES AND HEADLANDS COULD GUST UP TO 60 TO 65
MPH...WHICH WOULD MAKE IT A FAIRLY MARGINAL EVENT.

FINALLY...RAPIDLY BUILDING SEAS WILL BRING THE POTENTIAL FOR
DANGEROUS HIGH SURF ALONG THE BEACHES BEGINNING AS EARLY AS LATER
TODAY. COASTAL VISITORS ARE ENCOURAGED TO STAY OUT OF THE SURF ZONE
AS LONG PERIOD SWELLS WILL REACH SHORE AND MAY SURPRISE INDIVIDUALS
WHO ARE UNAWARE. IN ADDITION...LARGE WAVES MAY WASH OVER BEACHES AND
JETTIES WITH LITTLE WARNING. SOME POTENTIAL EXISTS FOR MINOR TIDAL
OVERFLOW SUNDAY AND MONDAY...ESPECIALLY AROUND HIGH TIDES. THIS
THREAT COULD BE ENHANCED BY HIGH FLOWS ON RIVERS IN RESPONSE TO THE
RAINFALL THIS WEEKEND.

THE ATMOSPHERIC RIVER SPIGOT LOOKS LIKE IT FINALLY SHUTS OFF SUNDAY
NIGHT WITH DECREASING POPS INTO MONDAY AS HIGH PRESSURE PUSHES INTO
THE AREA FROM OFF THE CALIFORNIA COAST. HOWEVER RIVER FLOODING MAY
CONTINUE TO BE A THREAT AS THE SIGNIFICANT WEEKEND PRECIP DRAINS DOWN
FROM THE HIGHER TERRAIN. BOWEN/WEISHAAR

&&

.LONG TERM...MONDAY NIGHT THROUGH FRIDAY...AN UPPER LEVEL RIDGE WILL
AMPLIFY OVER THE REGION LATE MONDAY INTO TUESDAY. EXTENDED MODELS
AGREE ON A WEAK SHORTWAVE ATTEMPTING TO FLATTEN THE RIDGE TUESDAY
MORNING AS AN UPPER LEVEL TROUGH BEGINS TO DEEPEN IN THE GULF OF
ALASKA. CLOUDY AND RAINY CONDITIONS WILL LINGER INTO THE MIDDLE OF
NEXT WEEK AS THIS DIRTY RIDGE REMAINS OVER THE AREA. THE NEXT MORE
SIGNIFICANT SYSTEM ARRIVES LATE WEDNESDAY AFTERNOON AS THE UPPER
LEVEL TROUGH AXIS BECOMES MORE NEGATIVELY TILTED AND STARTS TO SHIFT
INLAND. THIS MARKS THE NEXT BEST SHOT FOR THE CASCADES TO FINALLY
SEE SOME SNOW ACCUMULATIONS...AS SNOW LEVELS DROP TO 2000-2500 FT
THROUGH CHRISTMAS DAY. HOLIDAY TRAVELERS HEADED OVER THE CASCADE
PASSES WILL CERTAINLY NEED TO MONITOR THE FORECAST. COLDER NORTH
FLOW WILL FOLLOW AND ALLOW TEMPERATURES TO COOL WELL BELOW NORMAL AS
CONDITIONS DRY OUT NEXT FRIDAY. /27

&&

.HYDROLOGY...CONFIDENCE CONTINUES TO INCREASE THAT A SIGNIFICANT
ATMOSPHERIC RIVER TYPE PRECIPITATION EVENT WILL IMPACT SOUTHWEST
WASHINGTON AND NORTHWEST OREGON OVER THE WEEKEND AND INTO EARLY NEXT
WEEK. PRECIPITATION WILL START LATE TONIGHT INTO EARLY SAT AS A WARM
FRONT PUSHES ONSHORE. THE BAROCLINIC ZONE WILL THEN STALL OVER THE
REGION LATER SAT AND REMAIN NEARLY STATIONARY INTO EARLY MON.
SIGNIFICANT SUB-TROPICAL MOISTURE WITH A LONG FETCH THAT STRETCHES
ALL THE WAY TO THE SOUTH CHINA SEA WILL FEED INTO THIS FRONTAL
SYSTEM...BRINGING THE LIKELIHOOD OF VERY LARGE RAINFALL TOTALS
ACROSS THE REGION. LOW AND MID LEVEL WINDS WILL SWITCH FROM
SOUTHERLY TO WESTERLY SAT AFTERNOON. THESE STRONG WESTERLY WINDS
WILL CONTINUE INTO EARLY MON...WHICH WILL CREATE SIGNIFICANT
OROGRAPHIC ENHANCEMENT TO THE PRECIPITATION ALONG THE HIGHER TERRAIN
OF THE COAST RANGE...FOOTHILLS...AND CASCADES. THESE AREAS ARE
EXPECTED TO SEE AROUND 6 TO 12 INCHES OVER RAIN THROUGH EARLY
MON...WITH LOCALIZED AREAS SEEING EVEN HIGHER AMOUNTS IN THE N
OREGON CASCADES. THE LOWER TERRAIN IS FORECASTED TO SEE
LOWER...ALTHOUGH STILL IMPRESSIVE TOTALS. WE EXPECT 4 TO 8 INCHES TO
FALL ALONG THE COAST...AND 2 TO 5 INCHES OVER THE INTERIOR LOWLANDS.

BASED ON THE LATEST FORECAST RAINFALL TOTALS...NUMEROUS AREA RIVERS
ARE NOW PROJECTED TO REACH FLOOD STAGE. A FEW LOCATIONS ARE EVEN
PROJECTED TO REACH MAJOR FLOOD STAGE. A FLOOD WATCH HAS BEEN ISSUED
FOR ALL OF SW WASHINGTON AND NW OREGON STARTING LATE SAT AFTERNOON
AND CONTINUING THROUGH MON. SOME OF THE FASTER RESPONDING RIVERS
DRAINING THE COAST RANGE AND CASCADES COULD REACH FLOOD STAGE AS
EARLY AS SAT EVENING. SLOWER RESPONDING AND MAIN STEM RIVERS WOULD
LIKELY NOT REACH FLOOD UNTIL LATER SUNDAY OR EARLY NEXT WEEK.

IN ADDITION TO THE FLOODING CONCERNS...EXCESSIVE RAINFALL HAS THE
POTENTIAL TO CREATE LANDSLIDES...DEBRIS FLOWS...AND EXCESSIVE RUNOFF
IN THE VICINITY OF RECENT WILDFIRE BURN SCARS. BURN SCARS FROM TWO
LARGE FIRES THIS SUMMER...THE 36 PIT FIRE IN THE CLACKAMAS RIVER
BASIN NEAR ESTACADA AND THE DECEPTION COMPLEX NEAR OAKRIDGE...WILL
BE PARTICULARLY VULNERABLE.

AS IS USUALLY THE CASE WITH THESE ATMOSPHERIC RIVER HEAVY
PRECIPITATION EVENTS...A LOT DEPENDS ON EXACTLY WHERE THE BAND OF
SUBTROPICAL MOISTURE SETS UP. THE FCST MODELS HAVE BEEN CONSISTENTLY
HIGHLIGHTING OUR REGION FOR SOME OF THE MOST SIGNIFICANT IMPACTS FOR
THE LAST SEVERAL DAYS. HOWEVER...THERE COULD STILL BE SHIFTS IN THE
EXACT POSITIONING OF THE SYSTEM...WHICH WOULD EFFECT PRECIPITATION
ESTIMATES AND RIVER FORECASTS. PLEASE CONTINUE TO FOLLOW THE LATEST
FORECASTS. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE).
PYLE

&&
&&


.AVIATION...A SHOWERY AIRMASS WILL LEAD TO PREDOMINANTLY VFR
CONDITIONS THROUGH THIS EVENING. A WARM FRONT SPREADING WIDESPREAD
LIGHT TO MODERATE RAIN INTO THE AREA OVERNIGHT SHOULD RESULT IN
A DETERIORATION OF CONDITIONS AT ALL TAF SITES AFTER 06Z
SATURDAY. EXPECT WIDESPREAD HIGH END IFR TO MVFR CONDITIONS
BETWEEN 09Z AND 18Z SATURDAY ACROSS NORTHWEST OREGON AND SOUTHWEST
WASHINGTON.

KPDX AND APPROACHES...AN UNSTABLE SHOWERY AIRMASS WILL LEAD TO A
MIX OF VFR AND MVFR CONDITIONS THROUGH 06Z SATURDAY. A WARM FRONT
WILL SPREAD STEADY RAIN INTO THE TERMINAL BETWEEN 09Z AND 18Z
SATURDAY. EXPECT FLIGHT CONDITIONS TO SHIFT MORE SOLIDLY INTO THE
MVFR CATEGORY DURING THIS TIME. /NEUMAN


&&

.MARINE...THE MAIN WEATHER STORY IN THE IMMEDIATE SHORT TERM IS
THAT SEAS CURRENTLY IN THE 10 TO 12 FT RANGE WILL NEARLY DOUBLE IN
HEIGHT TODAY...RISING INTO THE 20 TO 23 FT RANGE WITH A DOMINANT
PERIOD NEAR 18 TO 19 SECONDS. ANY SMALL CRAFT VESSELS ARE URGED
TO COME ONSHORE IMMEDIATELY AS HIGHER SEAS ARE BEGINNING TO
ARRIVE. BUOY 89 ABOUT 70 MILES OFFSHORE JUMPED TO 19 FT AT 19
SECONDS AT 2 PM...AND WILL LIKELY EXCEED 20 FT IN THE NEXT HOUR OR
TWO. THESE HIGHER SEAS WILL PUSH INTO THE INNER COASTAL WATERS
BETWEEN 4 AND 6 PM.

PEOPLE SHOULD AVOID WALKING AND CLIMBING ON JETTIES ALONG THE
OREGON AND WASHINGTON COASTS THROUGH SATURDAY...BUT ESPECIALLY
THIS AFTERNOON AND EVENING. THERE IS CONSIDERABLE CONCERN THAT
SNEAKER WAVES WILL RUN UP MUCH FARTHER UP THE BEACH THAN WAVES
OBSERVED OVER THE PREVIOUS 15 TO 30 MINUTES. UNDER SIMILAR
SCENARIOS...PEOPLE HAVE BEEN KILLED BY BEING SWEPT OFF THEIR FEET
AND DRAGGED OUT TO SEA BY THE RECEDING WATER OR BY THE WATER
DISLODGING STUCK DRIFTWOOD THAT SUBSEQUENTLY ROLES OVER AN
UNSUSPECTING PERSON. PLEASE BE COGNIZANT OF THIS WHEN RECREATING
ON THE BEACHES OF THE OREGON AND WASHINGTON COASTS THROUGH
SATURDAY.

THE NEXT FRONTAL STORM SYSTEM IS STILL ON TRACK TO IMPACT THE
WATERS LATE TONIGHT AND SATURDAY MORNING. EXPECT WINDS TO
GRADUALLY INCREASE TODAY AND TONIGHT...WITH SOLID GALE FORCE WINDS
OF 30 TO 40 KT WITH GUSTS OF 40 TO 45 KT EXPECTED ACROSS THE
WATERS BY SATURDAY MORNING. THERE IS A CHANCE GUSTS MAY APPROACH
50 KT WITHIN 20 NM OF THE COAST AS A SHORT LIVED COASTAL JET
DEVELOPS...PARTICULARLY ALONG THE CENTRAL OREGON COAST. THE GALE
WARNING FOR THE INNER WATERS MAY NEED TO BE UPGRADED TO A STORM
WARNING...BUT WILL LET SUBSEQUENT SHIFTS DIGEST ADDITIONAL MODEL
RUNS BEFORE MAKING THE CALL.

WHILE THE AFOREMENTIONED LARGE WESTERLY SWELL WILL SLOWLY SUBSIDE
SATURDAY...THIS RENEWED SHOT OF STRONG WINDS ACROSS THE
WATERS ON SATURDAY MORNING...WILL LIKELY KEEP SEAS FLIRTING WITH
20 FT MARK FOR MUCH OF THE DAYLIGHT HOURS ON SATURDAY. EXPECT THE
HIGHEST WINDS TO TAPER AROUND MIDDAY OR EARLY SATURDAY
AFTERNOON...WHICH WILL THEN ALLOW COMBINED SEAS TO BEGIN
SUBSIDING. HOWEVER...ADDITIONAL GUSTS OF 35 KT MAY LINGER ACROSS
THE WATERS INTO SATURDAY EVENING AS ANOTHER WEAK SURGE OF WINDS
ENTERS THE WATERS. THE GALE WARNING FOR LATE TONIGHT AND SATURDAY
MORNING WAS EXTENDED INTO SATURDAY EVENING TO COVER THIS
PERIOD...BUT CONFIDENCE IS CONSIDERABLY LOWER THAT THESE 35 KT
WIND GUSTS WILL OCCUR LATE SATURDAY AFTERNOON AND EVENING.
AGAIN...THE PRIMARY WINDOW OF CONCERN FOR THE HIGHEST WINDS ACROSS
THE WATERS WILL BE SATURDAY MORNING...AND CONFIDENCE IS HIGH THEY
WILL OCCUR.

SOUTHWESTERLY TO WESTERLY WINDS WILL CONTINUE INTO SUNDAY...KEEPING
SEAS WELL IN THE TEENS THROUGH SUNDAY NIGHT. SEAS MAY TEMPORARILY
BOTTOM OUT NEAR 10 FT EARLY NEXT WEEK BEFORE A WEAK FRONT...AND
ACCOMPANYING LARGER WESTERLY SWELL AROUND 15 FT SLIDES INTO THE
WATERS TOWARDS MIDWEEK.

HIGH TIDE NEAR TOKE POINT IS EXPECTED TO FLIRT WITH 11 FT ON
SATURDAY DUE TO A TIDAL ANOMALY NEAR 1 FT. HOWEVER...THE HEAVIEST
RAIN WILL NOT HAVE ARRIVED TO ALLOW THE FLOWS ON THE WILLAPA AND
NASELLE RIVERS TO INCREASE ENOUGH THAT MINOR TIDAL OVERFLOW
FLOODING WILL BE A CONCERN. WHILE THE TIDAL ANOMALY WILL LIKELY BE
SLIGHTLY LESS ON SUNDAY...THE SUBSTANTIAL INCREASE IN RIVER FLOWS
EXPECTED ON THE WILLAPA AND NASELLE RIVERS INCREASE OUR CONCERN ON
MINOR TIDAL OVERFLOW FLOODING OCCURRING AROUND THE TOWNS OF
RAYMOND...NASELLE AND OTHER LOW LYING SPOTS AROUND WILLAPA BAY
WASHINGTON. IN FACT...BY MIDDAY SUNDAY...SEVERAL OREGON COASTAL
RIVERS WILL LIKELY BE NEAR FLOOD STAGE OR EXCEEDING FLOOD STAGE SO
COASTAL FLOOD CONCERNS WILL LIKELY ENCOMPASS MUCH OF THE COAST.
DUE TO THE RIVERS REMAINING HIGH AND HIGH TIDAL CYCLES
CONTINUING...THESE TIDAL OVERFLOW CONCERNS COULD CERTAINLY LINGER
INTO MONDAY. EXPECT THESE ISSUES TO BE MOST PREVALENT BETWEEN
9 AM AND 3 PM ON SUNDAY/MONDAY. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR

     CASCADE FOOTHILLS IN LANE COUNTY-CASCADES IN LANE COUNTY-
     CENTRAL COAST RANGE OF WESTERN OREGON-CENTRAL COLUMBIA
     RIVER GORGE-CENTRAL OREGON COAST-CENTRAL WILLAMETTE VALLEY-
     COAST RANGE OF NORTHWEST OREGON-GREATER PORTLAND METRO AREA-
     LOWER COLUMBIA-NORTH OREGON COAST-NORTHERN OREGON CASCADE
     FOOTHILLS-NORTHERN OREGON CASCADES-SOUTH WILLAMETTE VALLEY-
     UPPER HOOD RIVER VALLEY-WESTERN COLUMBIA RIVER GORGE.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

WA...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR

     CENTRAL COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-I-5
     CORRIDOR IN COWLITZ COUNTY-SOUTH WASHINGTON CASCADE
     FOOTHILLS-SOUTH WASHINGTON CASCADES-SOUTH WASHINGTON COAST-
     WESTERN COLUMBIA RIVER GORGE-WILLAPA HILLS.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR SOUTH WASHINGTON
     COAST.

     WINTER WEATHER ADVISORY UNTIL 1 PM PST SATURDAY FOR SOUTH
     WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 AM PST SATURDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     GALE WARNING FROM 1 AM TO 9 PM PST SATURDAY FOR COASTAL WATERS
FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 AM PST SATURDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST
SUNDAY.

&&


$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.





000
FXUS66 KPQR 191937 CCA
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1048 AM PST FRI DEC 19 2014

.SYNOPSIS...SCATTERED SHOWERS WILL CONTINUE TODAY WITH SNOW SHOWERS
IN THE CASCADES. MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND
WITH AN ATMOSPHERIC RIVER PATTERN RESULTING IN HEAVY RAIN ACROSS MUCH
OF THE REGION...ESPECIALLY MOUNTAINOUS TERRAIN. THERE IS THE
POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO EARLY NEXT WEEK.
LONGER RANGE MODEL OUTPUT IS SUGGESTING A COLDER AIR MASS WILL SETTLE
OVER THE PACIFIC NORTHWEST LATE NEXT WEEK.

&&

.MORNING UPDATE...UPPER TROUGH LOOKS LIKE IT HAS JUST PASSED THE AREA THIS
MORNING AND AS SUCH SHOWER ACTIVITY IS LESSENING. WILL SEE SOME
CLEARING THIS AFTERNOON WITH SCATTERED SHOWERS BEFORE CLOUDS AND THEN
STRATIFORM PRECIP FROM THE NEXT SYSTEM BEGIN TO MOVE INTO THE AREA
EARLY THIS EVENING.

THERE HAVE NOT BEEN ANY SIGNIFICANT CHANGES IN THE MODELS THIS
MORNING AND WE APPEAR TO REMAIN ON TRACK FOR A SIGNIFICANT
ATMOSPHERIC RIVER EVENT BEGINNING TONIGHT. COMPARED WITH
YESTERDAY...IT LOOKS LIKE MODELS ARE SHOWING A SLIGHTLY LATER ONSET
OF TRUE WESTERLY 850 MB FLOW...WHICH WOULD SOMEWHAT LIMIT THE
OROGRAPHIC ENHANCEMENT DURING THE BEGINNING OF THE EVENT...BUT THAT
SHOULD NOT CHANGE STORM TOTAL QPF VERY MUCH. HAVE ISSUED A FLOOD
WATCH FOR THE ENTIRE FORECAST AREA BASED ON FORECASTS OF FLOOD OR
NEAR FLOOD STAGE AT MANY RIVER POINTS IN THE AREA.

MODELS ARE INDICATING COLD AIR WILL HANG AROUND THE S WASHINGTON
CASCADES A BIT LONGER THAN ELSEWHERE AND SW FLOW TONIGHT WILL FAVOR
OROGRAPHIC ENHANCEMENT THERE...SO HAVE ISSUED A WINTER WEATHER
ADVISORY FOR AREAS ABOVE 3500 FT. COULD ALSO SEE SOME SNOW
ACCUMULATION ABOVE 4000 FT AROUND AND EAST OF MT HOOD INTO TOMORROW
MORNING...BUT WIDESPREAD AMOUNTS LOOKS LIKE THEY`LL REMAIN LESS THAN
6 INCHES DURING ANY GIVEN 6 HR PERIOD SO HAVE NOT ISSUED ANYTHING FOR
THAT AREA AT THIS TIME. BOWEN

.SHORT TERM (PREVIOUS DISCUSSION)....TODAY THROUGH SUNDAY...THE MAIN
WEATHER FEATURE TODAY WILL BE THE COLD UPPER TROUGH. LATEST
MODEL GUIDANCE SHOWS THE BULK OF THE TROUGH THROUGH THE AREA BY
MIDDAY. SNOW LEVELS DROP TO BELOW THE CASCADES PASSES TODAY...BUT THE
MAJORITY OF THE QPF HAS ALREADY OCCURRED. NAM MODEL SOUNDING FOR KAST
WOULD INDICATE THE BEST POTENTIAL FOR THUNDERSTORMS TO BE THROUGH THE
MORNING HOURS. NAM SOUNDING VALID 17Z TODAY SHOWS AN LI OF 0 WITH A
PRETTY HEFTY SWEAT INDEX OF 335...WELL ABOVE THE GENERALIZED 250
SWEAT INDEX BENCHMARK USED FOR ELEVATED CONVECTIVE
CONFIDENCE. THE CONVECTIVE POTENTIAL THEN DIMINISHES IN THE AFTERNOON
AS THE AIR MASS ALOFT STARTS TO STABILIZE.

THE BIGGER STORY CONTINUES TO BE THE ATMOSPHERIC RIVER EVENT OVER THE
WEEKEND. LATEST MODEL RUNS ARE GENERALLY CONSISTENT WITH THEIR
RESPECTIVE PAST RUNS WITH FAIRLY DECENT CONTINUITY AMONGST THE
INDIVIDUAL MODELS. THE MAIN FORECAST ISSUES WILL BE THE FOCUS OF THE
HEAVIEST PRECIP AND THE DURATION. GFS HAS BEEN PERSISTENT IN
DIRECTING THE BAROCLINIC BAND OVER EXTREME SW WA AND NRN OREGON. THE
NAM AND ECMWF ARE FAIRLY SIMILAR...BUT THE ECMWF SEEMS TO FOCUS THE
HEAVIEST QPF OVER THE CENTRAL PART OF THE FORECAST AREA 12Z SUN
THROUGH 00Z MON. THE 00Z WRF-GFS 48-HR QPF TOTALS VALID 12Z SAT
THROUGH 12Z MON SHOW AT LEAST 3-6 INCHES FOR THE OREGON CASCADES AND
2-4 INCHES FOR THE OREGON COAST RANGE. IT HAS LOWER AMOUNTS IN THE S
WA CASCADES AND WILLAPA HILLS. GFS AND NAM HAVE STRONG ISENTROPIC
LIFT ALONG THE 290K SURFACE STARTING 12Z SAT AND CONTINUING THROUGH
SUN. 850 MB WLY FLOW OF 40-50 KT INTO THE OREGON COAST RANGE AND
CASCADES SAT THROUGH SUN WILL RESULT IN A HIGHLY EFFICIENT OROGRAPHIC
RAINFALL COMPONENT. LOOKING AT THE ENSEMBLE SITUATIONAL AWARENESS
TABLE...SPECIFICALLY THE ENSEMBLE MODEL CLIMATE QPF (OR M CLIMATE
QPF)...IT INDICATES A 99TH PERCENTILE OR MAX QPF EVENT FOR A GOOD
PORTION OF THE OREGON CASCADES SAT AFTERNOON THROUGH SUN MORNING.
THIS MEANS THAT THE GEFS ENSEMBLE IS FORECASTING AN INORDINATE AMOUNT
OF PRECIP COMPARED TO THE 1985-2012 WINTER ENSEMBLE MODEL CLIMATE.
WOULD NOT BE SURPRISED TO SEE 1.5 TO 2.0 INCHES PER SIX HOURS IN THE
CASCADES FOR A 12-18 PERIOD. FORTUNATELY...THERE IS NO LOW-ELEVATION
SNOW AND MINIMAL SNOW AT PASS LEVELS. HOWEVER...LATEST HYDRO GUIDANCE
SUGGESTS A FEW RIVERS WILL REACH FLOOD STAGE BY SUN OR MON. REFER TO
THE HYDROLOGY SECTION FOR MORE DETAILS.

DO NOT ANTICIPATE HIGH WIND HIGHLIGHTS FOR THE COASTAL AREAS BUT IT
WILL BE RATHER BLUSTERY. THE NAM INDICATES A KAST-KOTH GRADIENT OF
AROUND 10 MB BY LATE SAT AFTERNOON AND IN THE EVENING. THE BENCHMARK
GRADIENT IS AROUND 12 MB. EXPECT 45-55 MPH GUSTS ALONG THE BEACHES
AND HEADLANDS SAT THROUGH SAT NIGHT.

IN ADDITION...THOSE PLANNING TO BE ALONG THE COAST AT AREA BEACHES
SHOULD CLOSELY MONITOR THE CONDITIONS THIS WEEKEND. RAPIDLY BUILDING
SEAS WILL BRING THE POTENTIAL FOR DANGEROUS HIGH SURF ALONG THE
BEACHES AS EARLY AS TODAY. LONG PERIOD SWELLS MAY REACH SHORE AND
SURPRISE INDIVIDUALS WHO ARE UNAWARE. ANYONE ON THE BEACHES SHOULD
EXERCISE EXTREME CAUTION AND AVOID THE SURF ZONE AS LARGE WAVES MAY
WASH OVER BEACHES AND JETTIES WITH LITTLE WARNING. SOME POTENTIAL FOR
MINOR TIDAL OVERFLOW IS POSSIBLE FOR SATURDAY AND SUNDAY...ESPECIALLY
AROUND HIGH TIDES. THIS THREAT COULD BE ENHANCED BY HIGH FLOWS ON
RIVERS IN RESPONSE TO THE RAINFALL THIS WEEKEND.  WEISHAAR

&&

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...MODELS AGREE THE WEEKEND
ATMOSPHERIC RIVER EVENT WILL WIND DOWN SUNDAY NIGHT INTO MONDAY.
UPPER RIDGING AMPLIFIES MON...BUT THIS WILL LIKELY BE A DIRTY RIDGE
AS THE GFS AND ECMWF HOLD ON TO SOME QPF...ESPECIALLY ACROSS THE NRN
HALF OF THE FORECAST AREA. HAVE ADJUSTED POPS TO REFLECT THIS
THINKING. A WEAK WARM FRONT MAY BRUSH THE NRN ZONES MON NIGHT AND TUE
FOR SOME ADDITIONAL PRECIP. THE GFS AND ECMWF THEN BRING A COLDER
UPPER LEVEL TROUGH ACROSS THE AREA WED. THE ECMWF DROPS 1000-500 MB
THICKNESS VALUES TO NEAR 530 DM 00Z THU WITH A DECENT AMOUNT OF QPF.
THUS...THE CASCADES AND SKI AREAS MAY FINALLY GET A DECENT SHOT OF
SNOW. COLDER NORTH FLOW WILL FOLLOW AND ALLOW TEMPERATURES TO COOL
WELL BELOW NORMAL AS CONDITIONS DRY OUT LATE WEEK. WEISHAAR

&&

.HYDROLOGY...SITUATION SETTING UP FOR A MEMORABLE HYDROLOGIC EVENT
MAINLY FOR LATER THIS WEEKEND AND HEADING INTO NEXT WEEK. STRONG AND
DEEP MOIST WESTERLY FLOW WILL BEGIN CROSSING THE PACNW COAST COME
SATURDAY MORNING. A VERY LONG FETCH OF MOISTURE IS STRETCHING ACROSS
THE PACIFIC WITH ORIGINS WEST TO THE SOUTH CHINA SEA. THIS MOIST AIR
MASS WILL BE PUSHED EAST BY A 150 TO 170 KT JET AND WESTERLY 25 TO
50 KT LOWER LEVEL WINDS. AS SUCH...THIS CONTINUES TO GIVE THE
APPEARANCE OF A CLASSIC HIGH PRECIPITATION ATMOSPHERIC RIVER EVENT
WHERE THE DEEP MOIST FLOW WILL SPEND A SIGNIFICANT AMOUNT OF TIME
ON A NEARLY PERPENDICULAR COURSE AGAINST THE COAST RANGE WITH THE
CASCADES TAKING A BIT HIGHER OF THE IMPACT. AS OF THE MORNING MODEL
RUNS AND RECENT NWRFC UPDATES...IT APPEARS MULTIPLE RIVERS HAVE
POTENTIAL OF EXCEEDING FLOOD STAGE. ADDITIONALLY...THIS EVENT HAS
SUFFICIENT DEPTH TO BRING SIGNIFICANT RAINS TO THE NORTH OREGON AND
SOUTH WASHINGTON CASCADES WHERE RIVERS WILL ALSO SEE POTENTIAL FOR
NOTABLE FLOODING. HAVE ISSUED FLOOD WATCH FOR THE ENTIRE FORECAST
AREA. KEEP IN MIND THAT DETAILS WILL ALWAYS BE IN FLUX UNDER THESE
SCENARIOS AS SUBTLE NORTH/SOUTH SHIFTS COLD MAKE DRAMATIC DIFFERENCES
IN WHICH BASINS RECEIVE EXTENDED PERIODS OF MODERATE TO HEAVY RAIN.
PLEASE CONTINUE TO FOLLOW THE LATEST FORECASTS AND IMPACTS AS
CONDITIONS WARRANT. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE).
JBONK/BOWEN

&&

.AVIATION...A SHOWERY AIRMASS WILL LEAD TO PREDOMINANTLY VFR
CONDITIONS THROUGH THIS EVENING. A WARM FRONT SPREADING WIDESPREAD
LIGHT TO MODERATE RAIN INTO THE AREA OVERNIGHT SHOULD RESULT IN
A DETERIORATION AT ALL TAF SITES AFTER 06Z SATURDAY. EXPECT
WIDESPREAD HIGH END IFR TO MAINLY MVFR CONDITIONS BETWEEN 09Z
AND 18Z SATURDAY.

KPDX AND APPROACHES...AN UNSTABLE SHOWERY AIRMASS WILL LEAD TO
PREDOMINANTLY VFR CONDITIONS THROUGH AT LEAST 06Z SATURDAY. A WARM
FRONT WILL SPREAD STEADY RAIN INTO THE TERMINAL BETWEEN 09Z AND
18Z SATURDAY. EXPECT A GRADUAL DETERIORATION TO MAINLY MVFR
CONDITIONS DURING THIS TIME. /NEUMAN

&&

.MARINE...THE MAIN WEATHER STORY IN THE IMMEDIATE SHORT TERM IS
THAT SEAS CURRENTLY IN THE 10 TO 12 FT RANGE WILL NEARLY DOUBLE IN
HEIGHT TODAY...RISING INTO THE 20 TO 23 FT RANGE WITH DOMINANT
PERIODS NEAR 18 SECONDS. ANY SMALL CRAFT VESSELS ARE URGED TO COME
ONSHORE IMMEDIATELY AS HIGHER SEAS ARE BEGINNING TO ARRIVE. BUOY
89 ABOUT 70 MILES OFFSHORE IS ALREADY REPORTING SEAS NEAR 15 FT
AT 8 AM...AND WILL LIKELY EXCEED 20 FT BY EARLY AFTERNOON.

PEOPLE SHOULD AVOID WALKING AND CLIMBING ON JETTIES ALONG THE
OREGON AND WASHINGTON COASTS THROUGH SATURDAY...BUT ESPECIALLY
THIS AFTERNOON AND EVENING. THERE IS CONSIDERABLE CONCERN THAT
SNEAKER WAVES WILL POSE A RISK TO THE GENERAL PUBLIC WALKING ALONG
THE BEACHES THIS AFTERNOON AND EVENING. THIS GENERAL PATTERN OF A
LARGE INCOMING SWELL OFTEN ALLOWS UNWARY BEACH GOERS TO BE CAUGHT
OFF GUARD BY WAVES THAT RUN MUCH FARTHER UP THE BEACH THAN WAVES
OVER THE PREVIOUS 15 TO 30 MINUTES. UNDER SIMILAR SCENARIOS IN THE
PAST...WAVES HAVE BEEN KNOWN TO KNOCK UNWARY PEOPLE AND PETS OFF
THEIR FEET BEFORE THE RECEDING WATER PULLS THEM BACK INTO THE SURF
ZONE. IN ADDITION...THESE HIGHER WAVES CAN CAUSE DRIFTWOOD THAT
SUPERFICIALLY APPEARS LOCKED IN PLACE ALONG THE BEACH TO BECOME
MOBILE AND ROLL OVER AN UNSUSPECTING PERSON AS THE WAVE PUSHES
ASHORE AND THEN RECEDES. THIS HAPPENS NEARLY EVERY YEAR ALONG THE
OREGON COAST...AND THIS IS AN IDEAL SETUP FOR THESE LARGE SNEAKER
WAVES TO DO JUST THIS. PLEASE BE COGNIZANT OF THIS WHEN RECREATING
ON BEACHES TODAY AND TONIGHT.

THE NEXT FRONTAL STORM SYSTEM IS STILL ON TRACK TO IMPACT THE
WATERS LATE TONIGHT AND SATURDAY. EXPECT WINDS TO GRADUALLY
INCREASE TODAY AND TONIGHT...WITH SOLID GALE FORCE WINDS OF 30 TO
35 KT WITH GUSTS OF 40 TO 45 KT EXPECTED ACROSS THE WATERS BY
SATURDAY MORNING. THERE IS A CHANCE GUSTS MAY APPROACH 50 KT
WITHIN 20 NM OF THE COAST AS A SHORT LIVED COASTAL JET
DEVELOPS...ESPECIALLY ALONG THE CENTRAL OREGON COAST. WHILE THE
AFOREMENTIONED LARGE WESTERLY SWELL WILL BE SLOWLY TAPERING
SATURDAY...THIS RENEWED SHOT OF WINDS ACROSS THE WATERS...WILL
LIKELY KEEP SEAS FLIRTING WITH 20 FT FOR MUCH OF SATURDAY. EXPECT
THE HIGHEST WINDS TO TAPER AROUND MIDDAY OR EARLY SATURDAY
AFTERNOON. HOWEVER...ADDITIONAL GUSTS OF 35 KT MAY LINGER INTO
SATURDAY EVENING AS ANOTHER WEAK SURGE OF WINDS ENTERS THE WATERS.
OPTED TO EXTEND THE GALE WARNING INTO SATURDAY EVENING TO COVER
THIS PERIOD...BUT CONFIDENCE IS CONSIDERABLY LOWER THAT THESE 35
KT WIND GUSTS WILL OCCUR LATE SATURDAY AFTERNOON AND EVENING.
AGAIN...THE PRIMARY WINDOW FOR SOLID GALE FORCE WINDS WILL BE
SATURDAY MORNING AND CONFIDENCE IS HIGH.

WESTERLY WINDS WILL CONTINUE INTO SUNDAY...AND KEEP SEAS WELL INTO
THE TEENS THROUGH SUNDAY NIGHT. SEAS MAY TEMPORARILY BOTTOM OUT
NEAR 10 FT EARLY NEXT WEEK BEFORE A WEAK FRONT...AND ACCOMPANYING
LARGER SWELL SLIDES INTO THE WATERS TOWARDS MIDWEEK.

WILL CONTINUE TO INVESTIGATE WHETHER OR NOT A COASTAL FLOOD
ADVISORY FOR MINOR TIDAL OVERFLOW FLOODING WILL BE NECESSARY FOR
THE SOUTH WASHINGTON COAST CENTERED AROUND THE HIGH TIDE EXPECTED
TO OCCUR AT 11 AM SATURDAY. GIVEN THE WILLAPA AND NASELLE RIVER FLOWS
WILL BE WELL BELOW FLOOD STAGE...AND HIGH TIDE NEAR TOKE POINT IS
EXPECTED TO FLIRT WITH 11 FT WITH A TIDAL ANOMALY NEAR 1 FT...WE
ARE LEANING TOWARDS NOT ISSUING A COASTAL FLOOD ADVISORY FOR
SATURDAY. HOWEVER...A SIMILAR TIDE HEIGHT WILL OCCUR AROUND MIDDAY
SUNDAY. BY THIS TIME...FLOWS ON THE WILLAPA AND NASELLE RIVERS
WILL BE CONSIDERABLY HIGHER SO THERE IS AN INCREASED CONCERN THAT
MINOR TIDAL OVERFLOW FLOODING WILL OCCUR ALONG LOW LYING ROADS
AROUND RAYMOND...NASELLE AND THE WILLAPA BAY IN GENERAL IN
SOUTHWEST WASHINGTON. GIVEN WIDESPREAD COASTAL FLOODING IS NOT
EXPECTED...WE ARE OPTING TO NOT ISSUE A COASTAL FLOOD WATCH...AND
WILL LIKELY WAIT TO ISSUE THE ADVISORY UNTIL WE GATHER MORE GROUND
TRUTH DATA AND SUNDAY APPROACHES. THE PEAK TIME OF CONCERN ON
SUNDAY WILL BE FROM APPROXIMATELY 9 AM TO 3 PM. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES... OR...FLOOD WATCH FROM SATURDAY
     AFTERNOON THROUGH MONDAY AFTERNOON FOR CASCADE FOOTHILLS IN LANE
     COUNTY-CASCADES IN LANE COUNTY-CENTRAL COAST RANGE OF WESTERN
     OREGON-CENTRAL COLUMBIA RIVER GORGE-CENTRAL OREGON COAST-
     CENTRAL WILLAMETTE VALLEY-COAST RANGE OF NORTHWEST OREGON-
     GREATER PORTLAND METRO AREA-LOWER COLUMBIA-NORTH OREGON COAST-
     NORTHERN OREGON CASCADE FOOTHILLS-NORTHERN OREGON CASCADES-
     SOUTH WILLAMETTE VALLEY-UPPER HOOD RIVER VALLEY-WESTERN
     COLUMBIA RIVER GORGE.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

WA...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR
     CENTRAL COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-I-5
     CORRIDOR IN COWLITZ COUNTY-SOUTH WASHINGTON CASCADE
     FOOTHILLS-SOUTH WASHINGTON CASCADES-SOUTH WASHINGTON COAST-
     WESTERN COLUMBIA RIVER GORGE-WILLAPA HILLS.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR SOUTH WASHINGTON
     COAST.

     WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM PST
     SATURDAY FOR SOUTH WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 AM PST SATURDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     GALE WARNING FROM 1 AM TO 9 PM PST SATURDAY FOR COASTAL WATERS
     FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 AM PST SATURDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
     NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST
     SUNDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 191937 CCA
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1048 AM PST FRI DEC 19 2014

.SYNOPSIS...SCATTERED SHOWERS WILL CONTINUE TODAY WITH SNOW SHOWERS
IN THE CASCADES. MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND
WITH AN ATMOSPHERIC RIVER PATTERN RESULTING IN HEAVY RAIN ACROSS MUCH
OF THE REGION...ESPECIALLY MOUNTAINOUS TERRAIN. THERE IS THE
POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO EARLY NEXT WEEK.
LONGER RANGE MODEL OUTPUT IS SUGGESTING A COLDER AIR MASS WILL SETTLE
OVER THE PACIFIC NORTHWEST LATE NEXT WEEK.

&&

.MORNING UPDATE...UPPER TROUGH LOOKS LIKE IT HAS JUST PASSED THE AREA THIS
MORNING AND AS SUCH SHOWER ACTIVITY IS LESSENING. WILL SEE SOME
CLEARING THIS AFTERNOON WITH SCATTERED SHOWERS BEFORE CLOUDS AND THEN
STRATIFORM PRECIP FROM THE NEXT SYSTEM BEGIN TO MOVE INTO THE AREA
EARLY THIS EVENING.

THERE HAVE NOT BEEN ANY SIGNIFICANT CHANGES IN THE MODELS THIS
MORNING AND WE APPEAR TO REMAIN ON TRACK FOR A SIGNIFICANT
ATMOSPHERIC RIVER EVENT BEGINNING TONIGHT. COMPARED WITH
YESTERDAY...IT LOOKS LIKE MODELS ARE SHOWING A SLIGHTLY LATER ONSET
OF TRUE WESTERLY 850 MB FLOW...WHICH WOULD SOMEWHAT LIMIT THE
OROGRAPHIC ENHANCEMENT DURING THE BEGINNING OF THE EVENT...BUT THAT
SHOULD NOT CHANGE STORM TOTAL QPF VERY MUCH. HAVE ISSUED A FLOOD
WATCH FOR THE ENTIRE FORECAST AREA BASED ON FORECASTS OF FLOOD OR
NEAR FLOOD STAGE AT MANY RIVER POINTS IN THE AREA.

MODELS ARE INDICATING COLD AIR WILL HANG AROUND THE S WASHINGTON
CASCADES A BIT LONGER THAN ELSEWHERE AND SW FLOW TONIGHT WILL FAVOR
OROGRAPHIC ENHANCEMENT THERE...SO HAVE ISSUED A WINTER WEATHER
ADVISORY FOR AREAS ABOVE 3500 FT. COULD ALSO SEE SOME SNOW
ACCUMULATION ABOVE 4000 FT AROUND AND EAST OF MT HOOD INTO TOMORROW
MORNING...BUT WIDESPREAD AMOUNTS LOOKS LIKE THEY`LL REMAIN LESS THAN
6 INCHES DURING ANY GIVEN 6 HR PERIOD SO HAVE NOT ISSUED ANYTHING FOR
THAT AREA AT THIS TIME. BOWEN

.SHORT TERM (PREVIOUS DISCUSSION)....TODAY THROUGH SUNDAY...THE MAIN
WEATHER FEATURE TODAY WILL BE THE COLD UPPER TROUGH. LATEST
MODEL GUIDANCE SHOWS THE BULK OF THE TROUGH THROUGH THE AREA BY
MIDDAY. SNOW LEVELS DROP TO BELOW THE CASCADES PASSES TODAY...BUT THE
MAJORITY OF THE QPF HAS ALREADY OCCURRED. NAM MODEL SOUNDING FOR KAST
WOULD INDICATE THE BEST POTENTIAL FOR THUNDERSTORMS TO BE THROUGH THE
MORNING HOURS. NAM SOUNDING VALID 17Z TODAY SHOWS AN LI OF 0 WITH A
PRETTY HEFTY SWEAT INDEX OF 335...WELL ABOVE THE GENERALIZED 250
SWEAT INDEX BENCHMARK USED FOR ELEVATED CONVECTIVE
CONFIDENCE. THE CONVECTIVE POTENTIAL THEN DIMINISHES IN THE AFTERNOON
AS THE AIR MASS ALOFT STARTS TO STABILIZE.

THE BIGGER STORY CONTINUES TO BE THE ATMOSPHERIC RIVER EVENT OVER THE
WEEKEND. LATEST MODEL RUNS ARE GENERALLY CONSISTENT WITH THEIR
RESPECTIVE PAST RUNS WITH FAIRLY DECENT CONTINUITY AMONGST THE
INDIVIDUAL MODELS. THE MAIN FORECAST ISSUES WILL BE THE FOCUS OF THE
HEAVIEST PRECIP AND THE DURATION. GFS HAS BEEN PERSISTENT IN
DIRECTING THE BAROCLINIC BAND OVER EXTREME SW WA AND NRN OREGON. THE
NAM AND ECMWF ARE FAIRLY SIMILAR...BUT THE ECMWF SEEMS TO FOCUS THE
HEAVIEST QPF OVER THE CENTRAL PART OF THE FORECAST AREA 12Z SUN
THROUGH 00Z MON. THE 00Z WRF-GFS 48-HR QPF TOTALS VALID 12Z SAT
THROUGH 12Z MON SHOW AT LEAST 3-6 INCHES FOR THE OREGON CASCADES AND
2-4 INCHES FOR THE OREGON COAST RANGE. IT HAS LOWER AMOUNTS IN THE S
WA CASCADES AND WILLAPA HILLS. GFS AND NAM HAVE STRONG ISENTROPIC
LIFT ALONG THE 290K SURFACE STARTING 12Z SAT AND CONTINUING THROUGH
SUN. 850 MB WLY FLOW OF 40-50 KT INTO THE OREGON COAST RANGE AND
CASCADES SAT THROUGH SUN WILL RESULT IN A HIGHLY EFFICIENT OROGRAPHIC
RAINFALL COMPONENT. LOOKING AT THE ENSEMBLE SITUATIONAL AWARENESS
TABLE...SPECIFICALLY THE ENSEMBLE MODEL CLIMATE QPF (OR M CLIMATE
QPF)...IT INDICATES A 99TH PERCENTILE OR MAX QPF EVENT FOR A GOOD
PORTION OF THE OREGON CASCADES SAT AFTERNOON THROUGH SUN MORNING.
THIS MEANS THAT THE GEFS ENSEMBLE IS FORECASTING AN INORDINATE AMOUNT
OF PRECIP COMPARED TO THE 1985-2012 WINTER ENSEMBLE MODEL CLIMATE.
WOULD NOT BE SURPRISED TO SEE 1.5 TO 2.0 INCHES PER SIX HOURS IN THE
CASCADES FOR A 12-18 PERIOD. FORTUNATELY...THERE IS NO LOW-ELEVATION
SNOW AND MINIMAL SNOW AT PASS LEVELS. HOWEVER...LATEST HYDRO GUIDANCE
SUGGESTS A FEW RIVERS WILL REACH FLOOD STAGE BY SUN OR MON. REFER TO
THE HYDROLOGY SECTION FOR MORE DETAILS.

DO NOT ANTICIPATE HIGH WIND HIGHLIGHTS FOR THE COASTAL AREAS BUT IT
WILL BE RATHER BLUSTERY. THE NAM INDICATES A KAST-KOTH GRADIENT OF
AROUND 10 MB BY LATE SAT AFTERNOON AND IN THE EVENING. THE BENCHMARK
GRADIENT IS AROUND 12 MB. EXPECT 45-55 MPH GUSTS ALONG THE BEACHES
AND HEADLANDS SAT THROUGH SAT NIGHT.

IN ADDITION...THOSE PLANNING TO BE ALONG THE COAST AT AREA BEACHES
SHOULD CLOSELY MONITOR THE CONDITIONS THIS WEEKEND. RAPIDLY BUILDING
SEAS WILL BRING THE POTENTIAL FOR DANGEROUS HIGH SURF ALONG THE
BEACHES AS EARLY AS TODAY. LONG PERIOD SWELLS MAY REACH SHORE AND
SURPRISE INDIVIDUALS WHO ARE UNAWARE. ANYONE ON THE BEACHES SHOULD
EXERCISE EXTREME CAUTION AND AVOID THE SURF ZONE AS LARGE WAVES MAY
WASH OVER BEACHES AND JETTIES WITH LITTLE WARNING. SOME POTENTIAL FOR
MINOR TIDAL OVERFLOW IS POSSIBLE FOR SATURDAY AND SUNDAY...ESPECIALLY
AROUND HIGH TIDES. THIS THREAT COULD BE ENHANCED BY HIGH FLOWS ON
RIVERS IN RESPONSE TO THE RAINFALL THIS WEEKEND.  WEISHAAR

&&

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...MODELS AGREE THE WEEKEND
ATMOSPHERIC RIVER EVENT WILL WIND DOWN SUNDAY NIGHT INTO MONDAY.
UPPER RIDGING AMPLIFIES MON...BUT THIS WILL LIKELY BE A DIRTY RIDGE
AS THE GFS AND ECMWF HOLD ON TO SOME QPF...ESPECIALLY ACROSS THE NRN
HALF OF THE FORECAST AREA. HAVE ADJUSTED POPS TO REFLECT THIS
THINKING. A WEAK WARM FRONT MAY BRUSH THE NRN ZONES MON NIGHT AND TUE
FOR SOME ADDITIONAL PRECIP. THE GFS AND ECMWF THEN BRING A COLDER
UPPER LEVEL TROUGH ACROSS THE AREA WED. THE ECMWF DROPS 1000-500 MB
THICKNESS VALUES TO NEAR 530 DM 00Z THU WITH A DECENT AMOUNT OF QPF.
THUS...THE CASCADES AND SKI AREAS MAY FINALLY GET A DECENT SHOT OF
SNOW. COLDER NORTH FLOW WILL FOLLOW AND ALLOW TEMPERATURES TO COOL
WELL BELOW NORMAL AS CONDITIONS DRY OUT LATE WEEK. WEISHAAR

&&

.HYDROLOGY...SITUATION SETTING UP FOR A MEMORABLE HYDROLOGIC EVENT
MAINLY FOR LATER THIS WEEKEND AND HEADING INTO NEXT WEEK. STRONG AND
DEEP MOIST WESTERLY FLOW WILL BEGIN CROSSING THE PACNW COAST COME
SATURDAY MORNING. A VERY LONG FETCH OF MOISTURE IS STRETCHING ACROSS
THE PACIFIC WITH ORIGINS WEST TO THE SOUTH CHINA SEA. THIS MOIST AIR
MASS WILL BE PUSHED EAST BY A 150 TO 170 KT JET AND WESTERLY 25 TO
50 KT LOWER LEVEL WINDS. AS SUCH...THIS CONTINUES TO GIVE THE
APPEARANCE OF A CLASSIC HIGH PRECIPITATION ATMOSPHERIC RIVER EVENT
WHERE THE DEEP MOIST FLOW WILL SPEND A SIGNIFICANT AMOUNT OF TIME
ON A NEARLY PERPENDICULAR COURSE AGAINST THE COAST RANGE WITH THE
CASCADES TAKING A BIT HIGHER OF THE IMPACT. AS OF THE MORNING MODEL
RUNS AND RECENT NWRFC UPDATES...IT APPEARS MULTIPLE RIVERS HAVE
POTENTIAL OF EXCEEDING FLOOD STAGE. ADDITIONALLY...THIS EVENT HAS
SUFFICIENT DEPTH TO BRING SIGNIFICANT RAINS TO THE NORTH OREGON AND
SOUTH WASHINGTON CASCADES WHERE RIVERS WILL ALSO SEE POTENTIAL FOR
NOTABLE FLOODING. HAVE ISSUED FLOOD WATCH FOR THE ENTIRE FORECAST
AREA. KEEP IN MIND THAT DETAILS WILL ALWAYS BE IN FLUX UNDER THESE
SCENARIOS AS SUBTLE NORTH/SOUTH SHIFTS COLD MAKE DRAMATIC DIFFERENCES
IN WHICH BASINS RECEIVE EXTENDED PERIODS OF MODERATE TO HEAVY RAIN.
PLEASE CONTINUE TO FOLLOW THE LATEST FORECASTS AND IMPACTS AS
CONDITIONS WARRANT. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE).
JBONK/BOWEN

&&

.AVIATION...A SHOWERY AIRMASS WILL LEAD TO PREDOMINANTLY VFR
CONDITIONS THROUGH THIS EVENING. A WARM FRONT SPREADING WIDESPREAD
LIGHT TO MODERATE RAIN INTO THE AREA OVERNIGHT SHOULD RESULT IN
A DETERIORATION AT ALL TAF SITES AFTER 06Z SATURDAY. EXPECT
WIDESPREAD HIGH END IFR TO MAINLY MVFR CONDITIONS BETWEEN 09Z
AND 18Z SATURDAY.

KPDX AND APPROACHES...AN UNSTABLE SHOWERY AIRMASS WILL LEAD TO
PREDOMINANTLY VFR CONDITIONS THROUGH AT LEAST 06Z SATURDAY. A WARM
FRONT WILL SPREAD STEADY RAIN INTO THE TERMINAL BETWEEN 09Z AND
18Z SATURDAY. EXPECT A GRADUAL DETERIORATION TO MAINLY MVFR
CONDITIONS DURING THIS TIME. /NEUMAN

&&

.MARINE...THE MAIN WEATHER STORY IN THE IMMEDIATE SHORT TERM IS
THAT SEAS CURRENTLY IN THE 10 TO 12 FT RANGE WILL NEARLY DOUBLE IN
HEIGHT TODAY...RISING INTO THE 20 TO 23 FT RANGE WITH DOMINANT
PERIODS NEAR 18 SECONDS. ANY SMALL CRAFT VESSELS ARE URGED TO COME
ONSHORE IMMEDIATELY AS HIGHER SEAS ARE BEGINNING TO ARRIVE. BUOY
89 ABOUT 70 MILES OFFSHORE IS ALREADY REPORTING SEAS NEAR 15 FT
AT 8 AM...AND WILL LIKELY EXCEED 20 FT BY EARLY AFTERNOON.

PEOPLE SHOULD AVOID WALKING AND CLIMBING ON JETTIES ALONG THE
OREGON AND WASHINGTON COASTS THROUGH SATURDAY...BUT ESPECIALLY
THIS AFTERNOON AND EVENING. THERE IS CONSIDERABLE CONCERN THAT
SNEAKER WAVES WILL POSE A RISK TO THE GENERAL PUBLIC WALKING ALONG
THE BEACHES THIS AFTERNOON AND EVENING. THIS GENERAL PATTERN OF A
LARGE INCOMING SWELL OFTEN ALLOWS UNWARY BEACH GOERS TO BE CAUGHT
OFF GUARD BY WAVES THAT RUN MUCH FARTHER UP THE BEACH THAN WAVES
OVER THE PREVIOUS 15 TO 30 MINUTES. UNDER SIMILAR SCENARIOS IN THE
PAST...WAVES HAVE BEEN KNOWN TO KNOCK UNWARY PEOPLE AND PETS OFF
THEIR FEET BEFORE THE RECEDING WATER PULLS THEM BACK INTO THE SURF
ZONE. IN ADDITION...THESE HIGHER WAVES CAN CAUSE DRIFTWOOD THAT
SUPERFICIALLY APPEARS LOCKED IN PLACE ALONG THE BEACH TO BECOME
MOBILE AND ROLL OVER AN UNSUSPECTING PERSON AS THE WAVE PUSHES
ASHORE AND THEN RECEDES. THIS HAPPENS NEARLY EVERY YEAR ALONG THE
OREGON COAST...AND THIS IS AN IDEAL SETUP FOR THESE LARGE SNEAKER
WAVES TO DO JUST THIS. PLEASE BE COGNIZANT OF THIS WHEN RECREATING
ON BEACHES TODAY AND TONIGHT.

THE NEXT FRONTAL STORM SYSTEM IS STILL ON TRACK TO IMPACT THE
WATERS LATE TONIGHT AND SATURDAY. EXPECT WINDS TO GRADUALLY
INCREASE TODAY AND TONIGHT...WITH SOLID GALE FORCE WINDS OF 30 TO
35 KT WITH GUSTS OF 40 TO 45 KT EXPECTED ACROSS THE WATERS BY
SATURDAY MORNING. THERE IS A CHANCE GUSTS MAY APPROACH 50 KT
WITHIN 20 NM OF THE COAST AS A SHORT LIVED COASTAL JET
DEVELOPS...ESPECIALLY ALONG THE CENTRAL OREGON COAST. WHILE THE
AFOREMENTIONED LARGE WESTERLY SWELL WILL BE SLOWLY TAPERING
SATURDAY...THIS RENEWED SHOT OF WINDS ACROSS THE WATERS...WILL
LIKELY KEEP SEAS FLIRTING WITH 20 FT FOR MUCH OF SATURDAY. EXPECT
THE HIGHEST WINDS TO TAPER AROUND MIDDAY OR EARLY SATURDAY
AFTERNOON. HOWEVER...ADDITIONAL GUSTS OF 35 KT MAY LINGER INTO
SATURDAY EVENING AS ANOTHER WEAK SURGE OF WINDS ENTERS THE WATERS.
OPTED TO EXTEND THE GALE WARNING INTO SATURDAY EVENING TO COVER
THIS PERIOD...BUT CONFIDENCE IS CONSIDERABLY LOWER THAT THESE 35
KT WIND GUSTS WILL OCCUR LATE SATURDAY AFTERNOON AND EVENING.
AGAIN...THE PRIMARY WINDOW FOR SOLID GALE FORCE WINDS WILL BE
SATURDAY MORNING AND CONFIDENCE IS HIGH.

WESTERLY WINDS WILL CONTINUE INTO SUNDAY...AND KEEP SEAS WELL INTO
THE TEENS THROUGH SUNDAY NIGHT. SEAS MAY TEMPORARILY BOTTOM OUT
NEAR 10 FT EARLY NEXT WEEK BEFORE A WEAK FRONT...AND ACCOMPANYING
LARGER SWELL SLIDES INTO THE WATERS TOWARDS MIDWEEK.

WILL CONTINUE TO INVESTIGATE WHETHER OR NOT A COASTAL FLOOD
ADVISORY FOR MINOR TIDAL OVERFLOW FLOODING WILL BE NECESSARY FOR
THE SOUTH WASHINGTON COAST CENTERED AROUND THE HIGH TIDE EXPECTED
TO OCCUR AT 11 AM SATURDAY. GIVEN THE WILLAPA AND NASELLE RIVER FLOWS
WILL BE WELL BELOW FLOOD STAGE...AND HIGH TIDE NEAR TOKE POINT IS
EXPECTED TO FLIRT WITH 11 FT WITH A TIDAL ANOMALY NEAR 1 FT...WE
ARE LEANING TOWARDS NOT ISSUING A COASTAL FLOOD ADVISORY FOR
SATURDAY. HOWEVER...A SIMILAR TIDE HEIGHT WILL OCCUR AROUND MIDDAY
SUNDAY. BY THIS TIME...FLOWS ON THE WILLAPA AND NASELLE RIVERS
WILL BE CONSIDERABLY HIGHER SO THERE IS AN INCREASED CONCERN THAT
MINOR TIDAL OVERFLOW FLOODING WILL OCCUR ALONG LOW LYING ROADS
AROUND RAYMOND...NASELLE AND THE WILLAPA BAY IN GENERAL IN
SOUTHWEST WASHINGTON. GIVEN WIDESPREAD COASTAL FLOODING IS NOT
EXPECTED...WE ARE OPTING TO NOT ISSUE A COASTAL FLOOD WATCH...AND
WILL LIKELY WAIT TO ISSUE THE ADVISORY UNTIL WE GATHER MORE GROUND
TRUTH DATA AND SUNDAY APPROACHES. THE PEAK TIME OF CONCERN ON
SUNDAY WILL BE FROM APPROXIMATELY 9 AM TO 3 PM. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES... OR...FLOOD WATCH FROM SATURDAY
     AFTERNOON THROUGH MONDAY AFTERNOON FOR CASCADE FOOTHILLS IN LANE
     COUNTY-CASCADES IN LANE COUNTY-CENTRAL COAST RANGE OF WESTERN
     OREGON-CENTRAL COLUMBIA RIVER GORGE-CENTRAL OREGON COAST-
     CENTRAL WILLAMETTE VALLEY-COAST RANGE OF NORTHWEST OREGON-
     GREATER PORTLAND METRO AREA-LOWER COLUMBIA-NORTH OREGON COAST-
     NORTHERN OREGON CASCADE FOOTHILLS-NORTHERN OREGON CASCADES-
     SOUTH WILLAMETTE VALLEY-UPPER HOOD RIVER VALLEY-WESTERN
     COLUMBIA RIVER GORGE.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

WA...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR
     CENTRAL COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-I-5
     CORRIDOR IN COWLITZ COUNTY-SOUTH WASHINGTON CASCADE
     FOOTHILLS-SOUTH WASHINGTON CASCADES-SOUTH WASHINGTON COAST-
     WESTERN COLUMBIA RIVER GORGE-WILLAPA HILLS.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR SOUTH WASHINGTON
     COAST.

     WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM PST
     SATURDAY FOR SOUTH WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 AM PST SATURDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     GALE WARNING FROM 1 AM TO 9 PM PST SATURDAY FOR COASTAL WATERS
     FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 AM PST SATURDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
     NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST
     SUNDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.





000
FXUS66 KPQR 191937 CCA
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1048 AM PST FRI DEC 19 2014

.SYNOPSIS...SCATTERED SHOWERS WILL CONTINUE TODAY WITH SNOW SHOWERS
IN THE CASCADES. MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND
WITH AN ATMOSPHERIC RIVER PATTERN RESULTING IN HEAVY RAIN ACROSS MUCH
OF THE REGION...ESPECIALLY MOUNTAINOUS TERRAIN. THERE IS THE
POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO EARLY NEXT WEEK.
LONGER RANGE MODEL OUTPUT IS SUGGESTING A COLDER AIR MASS WILL SETTLE
OVER THE PACIFIC NORTHWEST LATE NEXT WEEK.

&&

.MORNING UPDATE...UPPER TROUGH LOOKS LIKE IT HAS JUST PASSED THE AREA THIS
MORNING AND AS SUCH SHOWER ACTIVITY IS LESSENING. WILL SEE SOME
CLEARING THIS AFTERNOON WITH SCATTERED SHOWERS BEFORE CLOUDS AND THEN
STRATIFORM PRECIP FROM THE NEXT SYSTEM BEGIN TO MOVE INTO THE AREA
EARLY THIS EVENING.

THERE HAVE NOT BEEN ANY SIGNIFICANT CHANGES IN THE MODELS THIS
MORNING AND WE APPEAR TO REMAIN ON TRACK FOR A SIGNIFICANT
ATMOSPHERIC RIVER EVENT BEGINNING TONIGHT. COMPARED WITH
YESTERDAY...IT LOOKS LIKE MODELS ARE SHOWING A SLIGHTLY LATER ONSET
OF TRUE WESTERLY 850 MB FLOW...WHICH WOULD SOMEWHAT LIMIT THE
OROGRAPHIC ENHANCEMENT DURING THE BEGINNING OF THE EVENT...BUT THAT
SHOULD NOT CHANGE STORM TOTAL QPF VERY MUCH. HAVE ISSUED A FLOOD
WATCH FOR THE ENTIRE FORECAST AREA BASED ON FORECASTS OF FLOOD OR
NEAR FLOOD STAGE AT MANY RIVER POINTS IN THE AREA.

MODELS ARE INDICATING COLD AIR WILL HANG AROUND THE S WASHINGTON
CASCADES A BIT LONGER THAN ELSEWHERE AND SW FLOW TONIGHT WILL FAVOR
OROGRAPHIC ENHANCEMENT THERE...SO HAVE ISSUED A WINTER WEATHER
ADVISORY FOR AREAS ABOVE 3500 FT. COULD ALSO SEE SOME SNOW
ACCUMULATION ABOVE 4000 FT AROUND AND EAST OF MT HOOD INTO TOMORROW
MORNING...BUT WIDESPREAD AMOUNTS LOOKS LIKE THEY`LL REMAIN LESS THAN
6 INCHES DURING ANY GIVEN 6 HR PERIOD SO HAVE NOT ISSUED ANYTHING FOR
THAT AREA AT THIS TIME. BOWEN

.SHORT TERM (PREVIOUS DISCUSSION)....TODAY THROUGH SUNDAY...THE MAIN
WEATHER FEATURE TODAY WILL BE THE COLD UPPER TROUGH. LATEST
MODEL GUIDANCE SHOWS THE BULK OF THE TROUGH THROUGH THE AREA BY
MIDDAY. SNOW LEVELS DROP TO BELOW THE CASCADES PASSES TODAY...BUT THE
MAJORITY OF THE QPF HAS ALREADY OCCURRED. NAM MODEL SOUNDING FOR KAST
WOULD INDICATE THE BEST POTENTIAL FOR THUNDERSTORMS TO BE THROUGH THE
MORNING HOURS. NAM SOUNDING VALID 17Z TODAY SHOWS AN LI OF 0 WITH A
PRETTY HEFTY SWEAT INDEX OF 335...WELL ABOVE THE GENERALIZED 250
SWEAT INDEX BENCHMARK USED FOR ELEVATED CONVECTIVE
CONFIDENCE. THE CONVECTIVE POTENTIAL THEN DIMINISHES IN THE AFTERNOON
AS THE AIR MASS ALOFT STARTS TO STABILIZE.

THE BIGGER STORY CONTINUES TO BE THE ATMOSPHERIC RIVER EVENT OVER THE
WEEKEND. LATEST MODEL RUNS ARE GENERALLY CONSISTENT WITH THEIR
RESPECTIVE PAST RUNS WITH FAIRLY DECENT CONTINUITY AMONGST THE
INDIVIDUAL MODELS. THE MAIN FORECAST ISSUES WILL BE THE FOCUS OF THE
HEAVIEST PRECIP AND THE DURATION. GFS HAS BEEN PERSISTENT IN
DIRECTING THE BAROCLINIC BAND OVER EXTREME SW WA AND NRN OREGON. THE
NAM AND ECMWF ARE FAIRLY SIMILAR...BUT THE ECMWF SEEMS TO FOCUS THE
HEAVIEST QPF OVER THE CENTRAL PART OF THE FORECAST AREA 12Z SUN
THROUGH 00Z MON. THE 00Z WRF-GFS 48-HR QPF TOTALS VALID 12Z SAT
THROUGH 12Z MON SHOW AT LEAST 3-6 INCHES FOR THE OREGON CASCADES AND
2-4 INCHES FOR THE OREGON COAST RANGE. IT HAS LOWER AMOUNTS IN THE S
WA CASCADES AND WILLAPA HILLS. GFS AND NAM HAVE STRONG ISENTROPIC
LIFT ALONG THE 290K SURFACE STARTING 12Z SAT AND CONTINUING THROUGH
SUN. 850 MB WLY FLOW OF 40-50 KT INTO THE OREGON COAST RANGE AND
CASCADES SAT THROUGH SUN WILL RESULT IN A HIGHLY EFFICIENT OROGRAPHIC
RAINFALL COMPONENT. LOOKING AT THE ENSEMBLE SITUATIONAL AWARENESS
TABLE...SPECIFICALLY THE ENSEMBLE MODEL CLIMATE QPF (OR M CLIMATE
QPF)...IT INDICATES A 99TH PERCENTILE OR MAX QPF EVENT FOR A GOOD
PORTION OF THE OREGON CASCADES SAT AFTERNOON THROUGH SUN MORNING.
THIS MEANS THAT THE GEFS ENSEMBLE IS FORECASTING AN INORDINATE AMOUNT
OF PRECIP COMPARED TO THE 1985-2012 WINTER ENSEMBLE MODEL CLIMATE.
WOULD NOT BE SURPRISED TO SEE 1.5 TO 2.0 INCHES PER SIX HOURS IN THE
CASCADES FOR A 12-18 PERIOD. FORTUNATELY...THERE IS NO LOW-ELEVATION
SNOW AND MINIMAL SNOW AT PASS LEVELS. HOWEVER...LATEST HYDRO GUIDANCE
SUGGESTS A FEW RIVERS WILL REACH FLOOD STAGE BY SUN OR MON. REFER TO
THE HYDROLOGY SECTION FOR MORE DETAILS.

DO NOT ANTICIPATE HIGH WIND HIGHLIGHTS FOR THE COASTAL AREAS BUT IT
WILL BE RATHER BLUSTERY. THE NAM INDICATES A KAST-KOTH GRADIENT OF
AROUND 10 MB BY LATE SAT AFTERNOON AND IN THE EVENING. THE BENCHMARK
GRADIENT IS AROUND 12 MB. EXPECT 45-55 MPH GUSTS ALONG THE BEACHES
AND HEADLANDS SAT THROUGH SAT NIGHT.

IN ADDITION...THOSE PLANNING TO BE ALONG THE COAST AT AREA BEACHES
SHOULD CLOSELY MONITOR THE CONDITIONS THIS WEEKEND. RAPIDLY BUILDING
SEAS WILL BRING THE POTENTIAL FOR DANGEROUS HIGH SURF ALONG THE
BEACHES AS EARLY AS TODAY. LONG PERIOD SWELLS MAY REACH SHORE AND
SURPRISE INDIVIDUALS WHO ARE UNAWARE. ANYONE ON THE BEACHES SHOULD
EXERCISE EXTREME CAUTION AND AVOID THE SURF ZONE AS LARGE WAVES MAY
WASH OVER BEACHES AND JETTIES WITH LITTLE WARNING. SOME POTENTIAL FOR
MINOR TIDAL OVERFLOW IS POSSIBLE FOR SATURDAY AND SUNDAY...ESPECIALLY
AROUND HIGH TIDES. THIS THREAT COULD BE ENHANCED BY HIGH FLOWS ON
RIVERS IN RESPONSE TO THE RAINFALL THIS WEEKEND.  WEISHAAR

&&

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...MODELS AGREE THE WEEKEND
ATMOSPHERIC RIVER EVENT WILL WIND DOWN SUNDAY NIGHT INTO MONDAY.
UPPER RIDGING AMPLIFIES MON...BUT THIS WILL LIKELY BE A DIRTY RIDGE
AS THE GFS AND ECMWF HOLD ON TO SOME QPF...ESPECIALLY ACROSS THE NRN
HALF OF THE FORECAST AREA. HAVE ADJUSTED POPS TO REFLECT THIS
THINKING. A WEAK WARM FRONT MAY BRUSH THE NRN ZONES MON NIGHT AND TUE
FOR SOME ADDITIONAL PRECIP. THE GFS AND ECMWF THEN BRING A COLDER
UPPER LEVEL TROUGH ACROSS THE AREA WED. THE ECMWF DROPS 1000-500 MB
THICKNESS VALUES TO NEAR 530 DM 00Z THU WITH A DECENT AMOUNT OF QPF.
THUS...THE CASCADES AND SKI AREAS MAY FINALLY GET A DECENT SHOT OF
SNOW. COLDER NORTH FLOW WILL FOLLOW AND ALLOW TEMPERATURES TO COOL
WELL BELOW NORMAL AS CONDITIONS DRY OUT LATE WEEK. WEISHAAR

&&

.HYDROLOGY...SITUATION SETTING UP FOR A MEMORABLE HYDROLOGIC EVENT
MAINLY FOR LATER THIS WEEKEND AND HEADING INTO NEXT WEEK. STRONG AND
DEEP MOIST WESTERLY FLOW WILL BEGIN CROSSING THE PACNW COAST COME
SATURDAY MORNING. A VERY LONG FETCH OF MOISTURE IS STRETCHING ACROSS
THE PACIFIC WITH ORIGINS WEST TO THE SOUTH CHINA SEA. THIS MOIST AIR
MASS WILL BE PUSHED EAST BY A 150 TO 170 KT JET AND WESTERLY 25 TO
50 KT LOWER LEVEL WINDS. AS SUCH...THIS CONTINUES TO GIVE THE
APPEARANCE OF A CLASSIC HIGH PRECIPITATION ATMOSPHERIC RIVER EVENT
WHERE THE DEEP MOIST FLOW WILL SPEND A SIGNIFICANT AMOUNT OF TIME
ON A NEARLY PERPENDICULAR COURSE AGAINST THE COAST RANGE WITH THE
CASCADES TAKING A BIT HIGHER OF THE IMPACT. AS OF THE MORNING MODEL
RUNS AND RECENT NWRFC UPDATES...IT APPEARS MULTIPLE RIVERS HAVE
POTENTIAL OF EXCEEDING FLOOD STAGE. ADDITIONALLY...THIS EVENT HAS
SUFFICIENT DEPTH TO BRING SIGNIFICANT RAINS TO THE NORTH OREGON AND
SOUTH WASHINGTON CASCADES WHERE RIVERS WILL ALSO SEE POTENTIAL FOR
NOTABLE FLOODING. HAVE ISSUED FLOOD WATCH FOR THE ENTIRE FORECAST
AREA. KEEP IN MIND THAT DETAILS WILL ALWAYS BE IN FLUX UNDER THESE
SCENARIOS AS SUBTLE NORTH/SOUTH SHIFTS COLD MAKE DRAMATIC DIFFERENCES
IN WHICH BASINS RECEIVE EXTENDED PERIODS OF MODERATE TO HEAVY RAIN.
PLEASE CONTINUE TO FOLLOW THE LATEST FORECASTS AND IMPACTS AS
CONDITIONS WARRANT. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE).
JBONK/BOWEN

&&

.AVIATION...A SHOWERY AIRMASS WILL LEAD TO PREDOMINANTLY VFR
CONDITIONS THROUGH THIS EVENING. A WARM FRONT SPREADING WIDESPREAD
LIGHT TO MODERATE RAIN INTO THE AREA OVERNIGHT SHOULD RESULT IN
A DETERIORATION AT ALL TAF SITES AFTER 06Z SATURDAY. EXPECT
WIDESPREAD HIGH END IFR TO MAINLY MVFR CONDITIONS BETWEEN 09Z
AND 18Z SATURDAY.

KPDX AND APPROACHES...AN UNSTABLE SHOWERY AIRMASS WILL LEAD TO
PREDOMINANTLY VFR CONDITIONS THROUGH AT LEAST 06Z SATURDAY. A WARM
FRONT WILL SPREAD STEADY RAIN INTO THE TERMINAL BETWEEN 09Z AND
18Z SATURDAY. EXPECT A GRADUAL DETERIORATION TO MAINLY MVFR
CONDITIONS DURING THIS TIME. /NEUMAN

&&

.MARINE...THE MAIN WEATHER STORY IN THE IMMEDIATE SHORT TERM IS
THAT SEAS CURRENTLY IN THE 10 TO 12 FT RANGE WILL NEARLY DOUBLE IN
HEIGHT TODAY...RISING INTO THE 20 TO 23 FT RANGE WITH DOMINANT
PERIODS NEAR 18 SECONDS. ANY SMALL CRAFT VESSELS ARE URGED TO COME
ONSHORE IMMEDIATELY AS HIGHER SEAS ARE BEGINNING TO ARRIVE. BUOY
89 ABOUT 70 MILES OFFSHORE IS ALREADY REPORTING SEAS NEAR 15 FT
AT 8 AM...AND WILL LIKELY EXCEED 20 FT BY EARLY AFTERNOON.

PEOPLE SHOULD AVOID WALKING AND CLIMBING ON JETTIES ALONG THE
OREGON AND WASHINGTON COASTS THROUGH SATURDAY...BUT ESPECIALLY
THIS AFTERNOON AND EVENING. THERE IS CONSIDERABLE CONCERN THAT
SNEAKER WAVES WILL POSE A RISK TO THE GENERAL PUBLIC WALKING ALONG
THE BEACHES THIS AFTERNOON AND EVENING. THIS GENERAL PATTERN OF A
LARGE INCOMING SWELL OFTEN ALLOWS UNWARY BEACH GOERS TO BE CAUGHT
OFF GUARD BY WAVES THAT RUN MUCH FARTHER UP THE BEACH THAN WAVES
OVER THE PREVIOUS 15 TO 30 MINUTES. UNDER SIMILAR SCENARIOS IN THE
PAST...WAVES HAVE BEEN KNOWN TO KNOCK UNWARY PEOPLE AND PETS OFF
THEIR FEET BEFORE THE RECEDING WATER PULLS THEM BACK INTO THE SURF
ZONE. IN ADDITION...THESE HIGHER WAVES CAN CAUSE DRIFTWOOD THAT
SUPERFICIALLY APPEARS LOCKED IN PLACE ALONG THE BEACH TO BECOME
MOBILE AND ROLL OVER AN UNSUSPECTING PERSON AS THE WAVE PUSHES
ASHORE AND THEN RECEDES. THIS HAPPENS NEARLY EVERY YEAR ALONG THE
OREGON COAST...AND THIS IS AN IDEAL SETUP FOR THESE LARGE SNEAKER
WAVES TO DO JUST THIS. PLEASE BE COGNIZANT OF THIS WHEN RECREATING
ON BEACHES TODAY AND TONIGHT.

THE NEXT FRONTAL STORM SYSTEM IS STILL ON TRACK TO IMPACT THE
WATERS LATE TONIGHT AND SATURDAY. EXPECT WINDS TO GRADUALLY
INCREASE TODAY AND TONIGHT...WITH SOLID GALE FORCE WINDS OF 30 TO
35 KT WITH GUSTS OF 40 TO 45 KT EXPECTED ACROSS THE WATERS BY
SATURDAY MORNING. THERE IS A CHANCE GUSTS MAY APPROACH 50 KT
WITHIN 20 NM OF THE COAST AS A SHORT LIVED COASTAL JET
DEVELOPS...ESPECIALLY ALONG THE CENTRAL OREGON COAST. WHILE THE
AFOREMENTIONED LARGE WESTERLY SWELL WILL BE SLOWLY TAPERING
SATURDAY...THIS RENEWED SHOT OF WINDS ACROSS THE WATERS...WILL
LIKELY KEEP SEAS FLIRTING WITH 20 FT FOR MUCH OF SATURDAY. EXPECT
THE HIGHEST WINDS TO TAPER AROUND MIDDAY OR EARLY SATURDAY
AFTERNOON. HOWEVER...ADDITIONAL GUSTS OF 35 KT MAY LINGER INTO
SATURDAY EVENING AS ANOTHER WEAK SURGE OF WINDS ENTERS THE WATERS.
OPTED TO EXTEND THE GALE WARNING INTO SATURDAY EVENING TO COVER
THIS PERIOD...BUT CONFIDENCE IS CONSIDERABLY LOWER THAT THESE 35
KT WIND GUSTS WILL OCCUR LATE SATURDAY AFTERNOON AND EVENING.
AGAIN...THE PRIMARY WINDOW FOR SOLID GALE FORCE WINDS WILL BE
SATURDAY MORNING AND CONFIDENCE IS HIGH.

WESTERLY WINDS WILL CONTINUE INTO SUNDAY...AND KEEP SEAS WELL INTO
THE TEENS THROUGH SUNDAY NIGHT. SEAS MAY TEMPORARILY BOTTOM OUT
NEAR 10 FT EARLY NEXT WEEK BEFORE A WEAK FRONT...AND ACCOMPANYING
LARGER SWELL SLIDES INTO THE WATERS TOWARDS MIDWEEK.

WILL CONTINUE TO INVESTIGATE WHETHER OR NOT A COASTAL FLOOD
ADVISORY FOR MINOR TIDAL OVERFLOW FLOODING WILL BE NECESSARY FOR
THE SOUTH WASHINGTON COAST CENTERED AROUND THE HIGH TIDE EXPECTED
TO OCCUR AT 11 AM SATURDAY. GIVEN THE WILLAPA AND NASELLE RIVER FLOWS
WILL BE WELL BELOW FLOOD STAGE...AND HIGH TIDE NEAR TOKE POINT IS
EXPECTED TO FLIRT WITH 11 FT WITH A TIDAL ANOMALY NEAR 1 FT...WE
ARE LEANING TOWARDS NOT ISSUING A COASTAL FLOOD ADVISORY FOR
SATURDAY. HOWEVER...A SIMILAR TIDE HEIGHT WILL OCCUR AROUND MIDDAY
SUNDAY. BY THIS TIME...FLOWS ON THE WILLAPA AND NASELLE RIVERS
WILL BE CONSIDERABLY HIGHER SO THERE IS AN INCREASED CONCERN THAT
MINOR TIDAL OVERFLOW FLOODING WILL OCCUR ALONG LOW LYING ROADS
AROUND RAYMOND...NASELLE AND THE WILLAPA BAY IN GENERAL IN
SOUTHWEST WASHINGTON. GIVEN WIDESPREAD COASTAL FLOODING IS NOT
EXPECTED...WE ARE OPTING TO NOT ISSUE A COASTAL FLOOD WATCH...AND
WILL LIKELY WAIT TO ISSUE THE ADVISORY UNTIL WE GATHER MORE GROUND
TRUTH DATA AND SUNDAY APPROACHES. THE PEAK TIME OF CONCERN ON
SUNDAY WILL BE FROM APPROXIMATELY 9 AM TO 3 PM. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES... OR...FLOOD WATCH FROM SATURDAY
     AFTERNOON THROUGH MONDAY AFTERNOON FOR CASCADE FOOTHILLS IN LANE
     COUNTY-CASCADES IN LANE COUNTY-CENTRAL COAST RANGE OF WESTERN
     OREGON-CENTRAL COLUMBIA RIVER GORGE-CENTRAL OREGON COAST-
     CENTRAL WILLAMETTE VALLEY-COAST RANGE OF NORTHWEST OREGON-
     GREATER PORTLAND METRO AREA-LOWER COLUMBIA-NORTH OREGON COAST-
     NORTHERN OREGON CASCADE FOOTHILLS-NORTHERN OREGON CASCADES-
     SOUTH WILLAMETTE VALLEY-UPPER HOOD RIVER VALLEY-WESTERN
     COLUMBIA RIVER GORGE.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

WA...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR
     CENTRAL COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-I-5
     CORRIDOR IN COWLITZ COUNTY-SOUTH WASHINGTON CASCADE
     FOOTHILLS-SOUTH WASHINGTON CASCADES-SOUTH WASHINGTON COAST-
     WESTERN COLUMBIA RIVER GORGE-WILLAPA HILLS.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR SOUTH WASHINGTON
     COAST.

     WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM PST
     SATURDAY FOR SOUTH WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 AM PST SATURDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     GALE WARNING FROM 1 AM TO 9 PM PST SATURDAY FOR COASTAL WATERS
     FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 AM PST SATURDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
     NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST
     SUNDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.





000
FXUS66 KPQR 191937 CCA
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1048 AM PST FRI DEC 19 2014

.SYNOPSIS...SCATTERED SHOWERS WILL CONTINUE TODAY WITH SNOW SHOWERS
IN THE CASCADES. MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND
WITH AN ATMOSPHERIC RIVER PATTERN RESULTING IN HEAVY RAIN ACROSS MUCH
OF THE REGION...ESPECIALLY MOUNTAINOUS TERRAIN. THERE IS THE
POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO EARLY NEXT WEEK.
LONGER RANGE MODEL OUTPUT IS SUGGESTING A COLDER AIR MASS WILL SETTLE
OVER THE PACIFIC NORTHWEST LATE NEXT WEEK.

&&

.MORNING UPDATE...UPPER TROUGH LOOKS LIKE IT HAS JUST PASSED THE AREA THIS
MORNING AND AS SUCH SHOWER ACTIVITY IS LESSENING. WILL SEE SOME
CLEARING THIS AFTERNOON WITH SCATTERED SHOWERS BEFORE CLOUDS AND THEN
STRATIFORM PRECIP FROM THE NEXT SYSTEM BEGIN TO MOVE INTO THE AREA
EARLY THIS EVENING.

THERE HAVE NOT BEEN ANY SIGNIFICANT CHANGES IN THE MODELS THIS
MORNING AND WE APPEAR TO REMAIN ON TRACK FOR A SIGNIFICANT
ATMOSPHERIC RIVER EVENT BEGINNING TONIGHT. COMPARED WITH
YESTERDAY...IT LOOKS LIKE MODELS ARE SHOWING A SLIGHTLY LATER ONSET
OF TRUE WESTERLY 850 MB FLOW...WHICH WOULD SOMEWHAT LIMIT THE
OROGRAPHIC ENHANCEMENT DURING THE BEGINNING OF THE EVENT...BUT THAT
SHOULD NOT CHANGE STORM TOTAL QPF VERY MUCH. HAVE ISSUED A FLOOD
WATCH FOR THE ENTIRE FORECAST AREA BASED ON FORECASTS OF FLOOD OR
NEAR FLOOD STAGE AT MANY RIVER POINTS IN THE AREA.

MODELS ARE INDICATING COLD AIR WILL HANG AROUND THE S WASHINGTON
CASCADES A BIT LONGER THAN ELSEWHERE AND SW FLOW TONIGHT WILL FAVOR
OROGRAPHIC ENHANCEMENT THERE...SO HAVE ISSUED A WINTER WEATHER
ADVISORY FOR AREAS ABOVE 3500 FT. COULD ALSO SEE SOME SNOW
ACCUMULATION ABOVE 4000 FT AROUND AND EAST OF MT HOOD INTO TOMORROW
MORNING...BUT WIDESPREAD AMOUNTS LOOKS LIKE THEY`LL REMAIN LESS THAN
6 INCHES DURING ANY GIVEN 6 HR PERIOD SO HAVE NOT ISSUED ANYTHING FOR
THAT AREA AT THIS TIME. BOWEN

.SHORT TERM (PREVIOUS DISCUSSION)....TODAY THROUGH SUNDAY...THE MAIN
WEATHER FEATURE TODAY WILL BE THE COLD UPPER TROUGH. LATEST
MODEL GUIDANCE SHOWS THE BULK OF THE TROUGH THROUGH THE AREA BY
MIDDAY. SNOW LEVELS DROP TO BELOW THE CASCADES PASSES TODAY...BUT THE
MAJORITY OF THE QPF HAS ALREADY OCCURRED. NAM MODEL SOUNDING FOR KAST
WOULD INDICATE THE BEST POTENTIAL FOR THUNDERSTORMS TO BE THROUGH THE
MORNING HOURS. NAM SOUNDING VALID 17Z TODAY SHOWS AN LI OF 0 WITH A
PRETTY HEFTY SWEAT INDEX OF 335...WELL ABOVE THE GENERALIZED 250
SWEAT INDEX BENCHMARK USED FOR ELEVATED CONVECTIVE
CONFIDENCE. THE CONVECTIVE POTENTIAL THEN DIMINISHES IN THE AFTERNOON
AS THE AIR MASS ALOFT STARTS TO STABILIZE.

THE BIGGER STORY CONTINUES TO BE THE ATMOSPHERIC RIVER EVENT OVER THE
WEEKEND. LATEST MODEL RUNS ARE GENERALLY CONSISTENT WITH THEIR
RESPECTIVE PAST RUNS WITH FAIRLY DECENT CONTINUITY AMONGST THE
INDIVIDUAL MODELS. THE MAIN FORECAST ISSUES WILL BE THE FOCUS OF THE
HEAVIEST PRECIP AND THE DURATION. GFS HAS BEEN PERSISTENT IN
DIRECTING THE BAROCLINIC BAND OVER EXTREME SW WA AND NRN OREGON. THE
NAM AND ECMWF ARE FAIRLY SIMILAR...BUT THE ECMWF SEEMS TO FOCUS THE
HEAVIEST QPF OVER THE CENTRAL PART OF THE FORECAST AREA 12Z SUN
THROUGH 00Z MON. THE 00Z WRF-GFS 48-HR QPF TOTALS VALID 12Z SAT
THROUGH 12Z MON SHOW AT LEAST 3-6 INCHES FOR THE OREGON CASCADES AND
2-4 INCHES FOR THE OREGON COAST RANGE. IT HAS LOWER AMOUNTS IN THE S
WA CASCADES AND WILLAPA HILLS. GFS AND NAM HAVE STRONG ISENTROPIC
LIFT ALONG THE 290K SURFACE STARTING 12Z SAT AND CONTINUING THROUGH
SUN. 850 MB WLY FLOW OF 40-50 KT INTO THE OREGON COAST RANGE AND
CASCADES SAT THROUGH SUN WILL RESULT IN A HIGHLY EFFICIENT OROGRAPHIC
RAINFALL COMPONENT. LOOKING AT THE ENSEMBLE SITUATIONAL AWARENESS
TABLE...SPECIFICALLY THE ENSEMBLE MODEL CLIMATE QPF (OR M CLIMATE
QPF)...IT INDICATES A 99TH PERCENTILE OR MAX QPF EVENT FOR A GOOD
PORTION OF THE OREGON CASCADES SAT AFTERNOON THROUGH SUN MORNING.
THIS MEANS THAT THE GEFS ENSEMBLE IS FORECASTING AN INORDINATE AMOUNT
OF PRECIP COMPARED TO THE 1985-2012 WINTER ENSEMBLE MODEL CLIMATE.
WOULD NOT BE SURPRISED TO SEE 1.5 TO 2.0 INCHES PER SIX HOURS IN THE
CASCADES FOR A 12-18 PERIOD. FORTUNATELY...THERE IS NO LOW-ELEVATION
SNOW AND MINIMAL SNOW AT PASS LEVELS. HOWEVER...LATEST HYDRO GUIDANCE
SUGGESTS A FEW RIVERS WILL REACH FLOOD STAGE BY SUN OR MON. REFER TO
THE HYDROLOGY SECTION FOR MORE DETAILS.

DO NOT ANTICIPATE HIGH WIND HIGHLIGHTS FOR THE COASTAL AREAS BUT IT
WILL BE RATHER BLUSTERY. THE NAM INDICATES A KAST-KOTH GRADIENT OF
AROUND 10 MB BY LATE SAT AFTERNOON AND IN THE EVENING. THE BENCHMARK
GRADIENT IS AROUND 12 MB. EXPECT 45-55 MPH GUSTS ALONG THE BEACHES
AND HEADLANDS SAT THROUGH SAT NIGHT.

IN ADDITION...THOSE PLANNING TO BE ALONG THE COAST AT AREA BEACHES
SHOULD CLOSELY MONITOR THE CONDITIONS THIS WEEKEND. RAPIDLY BUILDING
SEAS WILL BRING THE POTENTIAL FOR DANGEROUS HIGH SURF ALONG THE
BEACHES AS EARLY AS TODAY. LONG PERIOD SWELLS MAY REACH SHORE AND
SURPRISE INDIVIDUALS WHO ARE UNAWARE. ANYONE ON THE BEACHES SHOULD
EXERCISE EXTREME CAUTION AND AVOID THE SURF ZONE AS LARGE WAVES MAY
WASH OVER BEACHES AND JETTIES WITH LITTLE WARNING. SOME POTENTIAL FOR
MINOR TIDAL OVERFLOW IS POSSIBLE FOR SATURDAY AND SUNDAY...ESPECIALLY
AROUND HIGH TIDES. THIS THREAT COULD BE ENHANCED BY HIGH FLOWS ON
RIVERS IN RESPONSE TO THE RAINFALL THIS WEEKEND.  WEISHAAR

&&

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...MODELS AGREE THE WEEKEND
ATMOSPHERIC RIVER EVENT WILL WIND DOWN SUNDAY NIGHT INTO MONDAY.
UPPER RIDGING AMPLIFIES MON...BUT THIS WILL LIKELY BE A DIRTY RIDGE
AS THE GFS AND ECMWF HOLD ON TO SOME QPF...ESPECIALLY ACROSS THE NRN
HALF OF THE FORECAST AREA. HAVE ADJUSTED POPS TO REFLECT THIS
THINKING. A WEAK WARM FRONT MAY BRUSH THE NRN ZONES MON NIGHT AND TUE
FOR SOME ADDITIONAL PRECIP. THE GFS AND ECMWF THEN BRING A COLDER
UPPER LEVEL TROUGH ACROSS THE AREA WED. THE ECMWF DROPS 1000-500 MB
THICKNESS VALUES TO NEAR 530 DM 00Z THU WITH A DECENT AMOUNT OF QPF.
THUS...THE CASCADES AND SKI AREAS MAY FINALLY GET A DECENT SHOT OF
SNOW. COLDER NORTH FLOW WILL FOLLOW AND ALLOW TEMPERATURES TO COOL
WELL BELOW NORMAL AS CONDITIONS DRY OUT LATE WEEK. WEISHAAR

&&

.HYDROLOGY...SITUATION SETTING UP FOR A MEMORABLE HYDROLOGIC EVENT
MAINLY FOR LATER THIS WEEKEND AND HEADING INTO NEXT WEEK. STRONG AND
DEEP MOIST WESTERLY FLOW WILL BEGIN CROSSING THE PACNW COAST COME
SATURDAY MORNING. A VERY LONG FETCH OF MOISTURE IS STRETCHING ACROSS
THE PACIFIC WITH ORIGINS WEST TO THE SOUTH CHINA SEA. THIS MOIST AIR
MASS WILL BE PUSHED EAST BY A 150 TO 170 KT JET AND WESTERLY 25 TO
50 KT LOWER LEVEL WINDS. AS SUCH...THIS CONTINUES TO GIVE THE
APPEARANCE OF A CLASSIC HIGH PRECIPITATION ATMOSPHERIC RIVER EVENT
WHERE THE DEEP MOIST FLOW WILL SPEND A SIGNIFICANT AMOUNT OF TIME
ON A NEARLY PERPENDICULAR COURSE AGAINST THE COAST RANGE WITH THE
CASCADES TAKING A BIT HIGHER OF THE IMPACT. AS OF THE MORNING MODEL
RUNS AND RECENT NWRFC UPDATES...IT APPEARS MULTIPLE RIVERS HAVE
POTENTIAL OF EXCEEDING FLOOD STAGE. ADDITIONALLY...THIS EVENT HAS
SUFFICIENT DEPTH TO BRING SIGNIFICANT RAINS TO THE NORTH OREGON AND
SOUTH WASHINGTON CASCADES WHERE RIVERS WILL ALSO SEE POTENTIAL FOR
NOTABLE FLOODING. HAVE ISSUED FLOOD WATCH FOR THE ENTIRE FORECAST
AREA. KEEP IN MIND THAT DETAILS WILL ALWAYS BE IN FLUX UNDER THESE
SCENARIOS AS SUBTLE NORTH/SOUTH SHIFTS COLD MAKE DRAMATIC DIFFERENCES
IN WHICH BASINS RECEIVE EXTENDED PERIODS OF MODERATE TO HEAVY RAIN.
PLEASE CONTINUE TO FOLLOW THE LATEST FORECASTS AND IMPACTS AS
CONDITIONS WARRANT. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE).
JBONK/BOWEN

&&

.AVIATION...A SHOWERY AIRMASS WILL LEAD TO PREDOMINANTLY VFR
CONDITIONS THROUGH THIS EVENING. A WARM FRONT SPREADING WIDESPREAD
LIGHT TO MODERATE RAIN INTO THE AREA OVERNIGHT SHOULD RESULT IN
A DETERIORATION AT ALL TAF SITES AFTER 06Z SATURDAY. EXPECT
WIDESPREAD HIGH END IFR TO MAINLY MVFR CONDITIONS BETWEEN 09Z
AND 18Z SATURDAY.

KPDX AND APPROACHES...AN UNSTABLE SHOWERY AIRMASS WILL LEAD TO
PREDOMINANTLY VFR CONDITIONS THROUGH AT LEAST 06Z SATURDAY. A WARM
FRONT WILL SPREAD STEADY RAIN INTO THE TERMINAL BETWEEN 09Z AND
18Z SATURDAY. EXPECT A GRADUAL DETERIORATION TO MAINLY MVFR
CONDITIONS DURING THIS TIME. /NEUMAN

&&

.MARINE...THE MAIN WEATHER STORY IN THE IMMEDIATE SHORT TERM IS
THAT SEAS CURRENTLY IN THE 10 TO 12 FT RANGE WILL NEARLY DOUBLE IN
HEIGHT TODAY...RISING INTO THE 20 TO 23 FT RANGE WITH DOMINANT
PERIODS NEAR 18 SECONDS. ANY SMALL CRAFT VESSELS ARE URGED TO COME
ONSHORE IMMEDIATELY AS HIGHER SEAS ARE BEGINNING TO ARRIVE. BUOY
89 ABOUT 70 MILES OFFSHORE IS ALREADY REPORTING SEAS NEAR 15 FT
AT 8 AM...AND WILL LIKELY EXCEED 20 FT BY EARLY AFTERNOON.

PEOPLE SHOULD AVOID WALKING AND CLIMBING ON JETTIES ALONG THE
OREGON AND WASHINGTON COASTS THROUGH SATURDAY...BUT ESPECIALLY
THIS AFTERNOON AND EVENING. THERE IS CONSIDERABLE CONCERN THAT
SNEAKER WAVES WILL POSE A RISK TO THE GENERAL PUBLIC WALKING ALONG
THE BEACHES THIS AFTERNOON AND EVENING. THIS GENERAL PATTERN OF A
LARGE INCOMING SWELL OFTEN ALLOWS UNWARY BEACH GOERS TO BE CAUGHT
OFF GUARD BY WAVES THAT RUN MUCH FARTHER UP THE BEACH THAN WAVES
OVER THE PREVIOUS 15 TO 30 MINUTES. UNDER SIMILAR SCENARIOS IN THE
PAST...WAVES HAVE BEEN KNOWN TO KNOCK UNWARY PEOPLE AND PETS OFF
THEIR FEET BEFORE THE RECEDING WATER PULLS THEM BACK INTO THE SURF
ZONE. IN ADDITION...THESE HIGHER WAVES CAN CAUSE DRIFTWOOD THAT
SUPERFICIALLY APPEARS LOCKED IN PLACE ALONG THE BEACH TO BECOME
MOBILE AND ROLL OVER AN UNSUSPECTING PERSON AS THE WAVE PUSHES
ASHORE AND THEN RECEDES. THIS HAPPENS NEARLY EVERY YEAR ALONG THE
OREGON COAST...AND THIS IS AN IDEAL SETUP FOR THESE LARGE SNEAKER
WAVES TO DO JUST THIS. PLEASE BE COGNIZANT OF THIS WHEN RECREATING
ON BEACHES TODAY AND TONIGHT.

THE NEXT FRONTAL STORM SYSTEM IS STILL ON TRACK TO IMPACT THE
WATERS LATE TONIGHT AND SATURDAY. EXPECT WINDS TO GRADUALLY
INCREASE TODAY AND TONIGHT...WITH SOLID GALE FORCE WINDS OF 30 TO
35 KT WITH GUSTS OF 40 TO 45 KT EXPECTED ACROSS THE WATERS BY
SATURDAY MORNING. THERE IS A CHANCE GUSTS MAY APPROACH 50 KT
WITHIN 20 NM OF THE COAST AS A SHORT LIVED COASTAL JET
DEVELOPS...ESPECIALLY ALONG THE CENTRAL OREGON COAST. WHILE THE
AFOREMENTIONED LARGE WESTERLY SWELL WILL BE SLOWLY TAPERING
SATURDAY...THIS RENEWED SHOT OF WINDS ACROSS THE WATERS...WILL
LIKELY KEEP SEAS FLIRTING WITH 20 FT FOR MUCH OF SATURDAY. EXPECT
THE HIGHEST WINDS TO TAPER AROUND MIDDAY OR EARLY SATURDAY
AFTERNOON. HOWEVER...ADDITIONAL GUSTS OF 35 KT MAY LINGER INTO
SATURDAY EVENING AS ANOTHER WEAK SURGE OF WINDS ENTERS THE WATERS.
OPTED TO EXTEND THE GALE WARNING INTO SATURDAY EVENING TO COVER
THIS PERIOD...BUT CONFIDENCE IS CONSIDERABLY LOWER THAT THESE 35
KT WIND GUSTS WILL OCCUR LATE SATURDAY AFTERNOON AND EVENING.
AGAIN...THE PRIMARY WINDOW FOR SOLID GALE FORCE WINDS WILL BE
SATURDAY MORNING AND CONFIDENCE IS HIGH.

WESTERLY WINDS WILL CONTINUE INTO SUNDAY...AND KEEP SEAS WELL INTO
THE TEENS THROUGH SUNDAY NIGHT. SEAS MAY TEMPORARILY BOTTOM OUT
NEAR 10 FT EARLY NEXT WEEK BEFORE A WEAK FRONT...AND ACCOMPANYING
LARGER SWELL SLIDES INTO THE WATERS TOWARDS MIDWEEK.

WILL CONTINUE TO INVESTIGATE WHETHER OR NOT A COASTAL FLOOD
ADVISORY FOR MINOR TIDAL OVERFLOW FLOODING WILL BE NECESSARY FOR
THE SOUTH WASHINGTON COAST CENTERED AROUND THE HIGH TIDE EXPECTED
TO OCCUR AT 11 AM SATURDAY. GIVEN THE WILLAPA AND NASELLE RIVER FLOWS
WILL BE WELL BELOW FLOOD STAGE...AND HIGH TIDE NEAR TOKE POINT IS
EXPECTED TO FLIRT WITH 11 FT WITH A TIDAL ANOMALY NEAR 1 FT...WE
ARE LEANING TOWARDS NOT ISSUING A COASTAL FLOOD ADVISORY FOR
SATURDAY. HOWEVER...A SIMILAR TIDE HEIGHT WILL OCCUR AROUND MIDDAY
SUNDAY. BY THIS TIME...FLOWS ON THE WILLAPA AND NASELLE RIVERS
WILL BE CONSIDERABLY HIGHER SO THERE IS AN INCREASED CONCERN THAT
MINOR TIDAL OVERFLOW FLOODING WILL OCCUR ALONG LOW LYING ROADS
AROUND RAYMOND...NASELLE AND THE WILLAPA BAY IN GENERAL IN
SOUTHWEST WASHINGTON. GIVEN WIDESPREAD COASTAL FLOODING IS NOT
EXPECTED...WE ARE OPTING TO NOT ISSUE A COASTAL FLOOD WATCH...AND
WILL LIKELY WAIT TO ISSUE THE ADVISORY UNTIL WE GATHER MORE GROUND
TRUTH DATA AND SUNDAY APPROACHES. THE PEAK TIME OF CONCERN ON
SUNDAY WILL BE FROM APPROXIMATELY 9 AM TO 3 PM. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES... OR...FLOOD WATCH FROM SATURDAY
     AFTERNOON THROUGH MONDAY AFTERNOON FOR CASCADE FOOTHILLS IN LANE
     COUNTY-CASCADES IN LANE COUNTY-CENTRAL COAST RANGE OF WESTERN
     OREGON-CENTRAL COLUMBIA RIVER GORGE-CENTRAL OREGON COAST-
     CENTRAL WILLAMETTE VALLEY-COAST RANGE OF NORTHWEST OREGON-
     GREATER PORTLAND METRO AREA-LOWER COLUMBIA-NORTH OREGON COAST-
     NORTHERN OREGON CASCADE FOOTHILLS-NORTHERN OREGON CASCADES-
     SOUTH WILLAMETTE VALLEY-UPPER HOOD RIVER VALLEY-WESTERN
     COLUMBIA RIVER GORGE.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

WA...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR
     CENTRAL COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-I-5
     CORRIDOR IN COWLITZ COUNTY-SOUTH WASHINGTON CASCADE
     FOOTHILLS-SOUTH WASHINGTON CASCADES-SOUTH WASHINGTON COAST-
     WESTERN COLUMBIA RIVER GORGE-WILLAPA HILLS.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR SOUTH WASHINGTON
     COAST.

     WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM PST
     SATURDAY FOR SOUTH WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 AM PST SATURDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     GALE WARNING FROM 1 AM TO 9 PM PST SATURDAY FOR COASTAL WATERS
     FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 AM PST SATURDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
     NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST
     SUNDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 191848
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1048 AM PST FRI DEC 19 2014

.SYNOPSIS...SCATTERED SHOWERS WILL CONTINUE TODAY WITH SNOW SHOWERS
IN THE CASCADES. MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND
WITH AN ATMOSPHERIC RIVER PATTERN RESULTING IN HEAVY RAIN ACROSS MUCH
OF THE REGION...ESPECIALLY MOUNTAINOUS TERRAIN. THERE IS THE
POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO EARLY NEXT WEEK.
LONGER RANGE MODEL OUTPUT IS SUGGESTING A COLDER AIR MASS WILL SETTLE
OVER THE PACIFIC NORTHWEST LATE NEXT WEEK.

&&

.MORNING UPDATE...UPPER TROUGH LOOKS LIKE IT HAS JUST PASSED THE AREA THIS
MORNING AND AS SUCH SHOWER ACTIVITY IS LESSENING. WILL SEE SOME
CLEARING THIS AFTERNOON WITH SCATTERED SHOWERS BEFORE CLOUDS AND THEN
STRATIFORM PRECIP FROM THE NEXT SYSTEM BEGIN TO MOVE INTO THE AREA
EARLY THIS EVENING.

THERE HAVE NOT BEEN ANY SIGNIFICANT CHANGES IN THE MODELS THIS
MORNING AND WE APPEAR TO REMAIN ON TRACK FOR A SIGNIFICANT
ATMOSPHERIC RIVER EVENT BEGINNING TONIGHT. COMPARED WITH
YESTERDAY...IT LOOKS LIKE MODELS ARE SHOWING A SLIGHTLY LATER ONSET
OF TRUE WESTERLY 850 MB FLOW...WHICH WOULD SOMEWHAT LIMIT THE
OROGRAPHIC ENHANCEMENT DURING THE BEGINNING OF THE EVENT...BUT THAT
SHOULD NOT CHANGE STORM TOTAL QPF VERY MUCH. HAVE ISSUED A FLOOD
WATCH FOR THE ENTIRE FORECAST AREA BASED ON FORECASTS OF FLOOD OR
NEAR FLOOD STAGE AT MANY RIVER POINTS IN THE AREA.

MODELS ARE INDICATING COLD AIR WILL HANG AROUND THE S WASHINGTON
CASCADES A BIT LONGER THAN ELSEWHERE AND SW FLOW TONIGHT WILL FAVOR
OROGRAPHIC ENHANCEMENT THERE...SO HAVE ISSUED A WINTER WEATHER
ADVISORY FOR AREAS ABOVE 3500 FT. COULD ALSO SEE SOME SNOW
ACCUMULATION ABOVE 4000 FT AROUND AND EAST OF MT HOOD INTO TOMORROW
MORNING...BUT WIDESPREAD AMOUNTS LOOKS LIKE THEY`LL REMAIN LESS THAN
6 INCHES DURING ANY GIVEN 6 HR PERIOD SO HAVE NOT ISSUED ANYTHING FOR
THAT AREA AT THIS TIME. BOWEN

.SHORT TERM (PREVIOUS DISCUSSION)....TODAY THROUGH SUNDAY...THE MAIN
WEATHER FEATURE TODAY WILL BE THE COLD UPPER TROUGH. LATEST
MODEL GUIDANCE SHOWS THE BULK OF THE TROUGH THROUGH THE AREA BY
MIDDAY. SNOW LEVELS DROP TO BELOW THE CASCADES PASSES TODAY...BUT THE
MAJORITY OF THE QPF HAS ALREADY OCCURRED. NAM MODEL SOUNDING FOR KAST
WOULD INDICATE THE BEST POTENTIAL FOR THUNDERSTORMS TO BE THROUGH THE
MORNING HOURS. NAM SOUNDING VALID 17Z TODAY SHOWS AN LI OF 0 WITH A
PRETTY HEFTY SWEAT INDEX OF 335...WELL ABOVE THE GENERALIZED 250
SWEAT INDEX BENCHMARK USED FOR ELEVATED CONVECTIVE
CONFIDENCE. THE CONVECTIVE POTENTIAL THEN DIMINISHES IN THE AFTERNOON
AS THE AIR MASS ALOFT STARTS TO STABILIZE.

THE BIGGER STORY CONTINUES TO BE THE ATMOSPHERIC RIVER EVENT OVER THE
WEEKEND. LATEST MODEL RUNS ARE GENERALLY CONSISTENT WITH THEIR
RESPECTIVE PAST RUNS WITH FAIRLY DECENT CONTINUITY AMONGST THE
INDIVIDUAL MODELS. THE MAIN FORECAST ISSUES WILL BE THE FOCUS OF THE
HEAVIEST PRECIP AND THE DURATION. GFS HAS BEEN PERSISTENT IN
DIRECTING THE BAROCLINIC BAND OVER EXTREME SW WA AND NRN OREGON. THE
NAM AND ECMWF ARE FAIRLY SIMILAR...BUT THE ECMWF SEEMS TO FOCUS THE
HEAVIEST QPF OVER THE CENTRAL PART OF THE FORECAST AREA 12Z SUN
THROUGH 00Z MON. THE 00Z WRF-GFS 48-HR QPF TOTALS VALID 12Z SAT
THROUGH 12Z MON SHOW AT LEAST 3-6 INCHES FOR THE OREGON CASCADES AND
2-4 INCHES FOR THE OREGON COAST RANGE. IT HAS LOWER AMOUNTS IN THE S
WA CASCADES AND WILLAPA HILLS. GFS AND NAM HAVE STRONG ISENTROPIC
LIFT ALONG THE 290K SURFACE STARTING 12Z SAT AND CONTINUING THROUGH
SUN. 850 MB WLY FLOW OF 40-50 KT INTO THE OREGON COAST RANGE AND
CASCADES SAT THROUGH SUN WILL RESULT IN A HIGHLY EFFICIENT OROGRAPHIC
RAINFALL COMPONENT. LOOKING AT THE ENSEMBLE SITUATIONAL AWARENESS
TABLE...SPECIFICALLY THE ENSEMBLE MODEL CLIMATE QPF (OR M CLIMATE
QPF)...IT INDICATES A 99TH PERCENTILE OR MAX QPF EVENT FOR A GOOD
PORTION OF THE OREGON CASCADES SAT AFTERNOON THROUGH SUN MORNING.
THIS MEANS THAT THE GEFS ENSEMBLE IS FORECASTING AN INORDINATE AMOUNT
OF PRECIP COMPARED TO THE 1985-2012 WINTER ENSEMBLE MODEL CLIMATE.
WOULD NOT BE SURPRISED TO SEE 1.5 TO 2.0 INCHES PER SIX HOURS IN THE
CASCADES FOR A 12-18 PERIOD. FORTUNATELY...THERE IS NO LOW-ELEVATION
SNOW AND MINIMAL SNOW AT PASS LEVELS. HOWEVER...LATEST HYDRO GUIDANCE
SUGGESTS A FEW RIVERS WILL REACH FLOOD STAGE BY SUN OR MON. REFER TO
THE HYDROLOGY SECTION FOR MORE DETAILS.

DO NOT ANTICIPATE HIGH WIND HIGHLIGHTS FOR THE COASTAL AREAS BUT IT
WILL BE RATHER BLUSTERY. THE NAM INDICATES A KAST-KOTH GRADIENT OF
AROUND 10 MB BY LATE SAT AFTERNOON AND IN THE EVENING. THE BENCHMARK
GRADIENT IS AROUND 12 MB. EXPECT 45-55 MPH GUSTS ALONG THE BEACHES
AND HEADLANDS SAT THROUGH SAT NIGHT.

IN ADDITION...THOSE PLANNING TO BE ALONG THE COAST AT AREA BEACHES
SHOULD CLOSELY MONITOR THE CONDITIONS THIS WEEKEND. RAPIDLY BUILDING
SEAS WILL BRING THE POTENTIAL FOR DANGEROUS HIGH SURF ALONG THE
BEACHES AS EARLY AS TODAY. LONG PERIOD SWELLS MAY REACH SHORE AND
SURPRISE INDIVIDUALS WHO ARE UNAWARE. ANYONE ON THE BEACHES SHOULD
EXERCISE EXTREME CAUTION AND AVOID THE SURF ZONE AS LARGE WAVES MAY
WASH OVER BEACHES AND JETTIES WITH LITTLE WARNING. SOME POTENTIAL FOR
MINOR TIDAL OVERFLOW IS POSSIBLE FOR SATURDAY AND SUNDAY...ESPECIALLY
AROUND HIGH TIDES. THIS THREAT COULD BE ENHANCED BY HIGH FLOWS ON
RIVERS IN RESPONSE TO THE RAINFALL THIS WEEKEND.  WEISHAAR

&&

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...MODELS AGREE THE WEEKEND
ATMOSPHERIC RIVER EVENT WILL WIND DOWN SUNDAY NIGHT INTO MONDAY.
UPPER RIDGING AMPLIFIES MON...BUT THIS WILL LIKELY BE A DIRTY RIDGE
AS THE GFS AND ECMWF HOLD ON TO SOME QPF...ESPECIALLY ACROSS THE NRN
HALF OF THE FORECAST AREA. HAVE ADJUSTED POPS TO REFLECT THIS
THINKING. A WEAK WARM FRONT MAY BRUSH THE NRN ZONES MON NIGHT AND TUE
FOR SOME ADDITIONAL PRECIP. THE GFS AND ECMWF THEN BRING A COLDER
UPPER LEVEL TROUGH ACROSS THE AREA WED. THE ECMWF DROPS 1000-500 MB
THICKNESS VALUES TO NEAR 530 DM 00Z THU WITH A DECENT AMOUNT OF QPF.
THUS...THE CASCADES AND SKI AREAS MAY FINALLY GET A DECENT SHOT OF
SNOW. COLDER NORTH FLOW WILL FOLLOW AND ALLOW TEMPERATURES TO COOL
WELL BELOW NORMAL AS CONDITIONS DRY OUT LATE WEEK. WEISHAAR

&&

.HYDROLOGY...SITUATION SETTING UP FOR A MEMORABLE HYDROLOGIC EVENT
MAINLY FOR LATER THIS WEEKEND AND HEADING INTO NEXT WEEK. STRONG AND
DEEP MOIST WESTERLY FLOW WILL BEGIN CROSSING THE PACNW COAST COME
SATURDAY MORNING. A VERY LONG FETCH OF MOISTURE IS STRETCHING ACROSS
THE PACIFIC WITH ORIGINS WEST TO THE SOUTH CHINA SEA. THIS MOIST AIR
MASS WILL BE PUSHED EAST BY A 150 TO 170 KT JET AND WESTERLY 25 TO
50 KT LOWER LEVEL WINDS. AS SUCH...THIS CONTINUES TO GIVE THE
APPEARANCE OF A CLASSIC HIGH PRECIPITATION ATMOSPHERIC RIVER EVENT
WHERE THE DEEP MOIST FLOW WILL SPEND A SIGNIFICANT AMOUNT OF TIME
ON A NEARLY PERPENDICULAR COURSE AGAINST THE COAST RANGE WITH THE
CASCADES TAKING A BIT HIGHER OF THE IMPACT. AS OF THE MORNING MODEL
RUNS AND RECENT NWRFC UPDATES...IT APPEARS MULTIPLE RIVERS HAVE
POTENTIAL OF EXCEEDING FLOOD STAGE. ADDITIONALLY...THIS EVENT HAS
SUFFICIENT DEPTH TO BRING SIGNIFICANT RAINS TO THE NORTH OREGON AND
SOUTH WASHINGTON CASCADES WHERE RIVERS WILL ALSO SEE POTENTIAL FOR
NOTABLE FLOODING. HAVE ISSUED FLOOD WATCH FOR THE ENTIRE FORECAST
AREA. KEEP IN MIND THAT DETAILS WILL ALWAYS BE IN FLUX UNDER THESE
SCENARIOS AS SUBTLE NORTH/SOUTH SHIFTS COLD MAKE DRAMATIC DIFFERENCES
IN WHICH BASINS RECEIVE EXTENDED PERIODS OF MODERATE TO HEAVY RAIN.
PLEASE CONTINUE TO FOLLOW THE LATEST FORECASTS AND IMPACTS AS
CONDITIONS WARRANT. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE).
JBONK/BOWEN

&&

.AVIATION...A SHOWERY AIRMASS WILL LEAD TO PREDOMINANTLY VFR
CONDITIONS THROUGH THIS EVENING. A WARM FRONT SPREADING WIDESPREAD
LIGHT TO MODERATE RAIN INTO THE AREA OVERNIGHT SHOULD RESULT IN
A DETERIORATION AT ALL TAF SITES AFTER 06Z SATURDAY. EXPECT
WIDESPREAD HIGH END IFR TO MAINLY MVFR CONDITIONS BETWEEN 09Z
AND 18Z SATURDAY.

KPDX AND APPROACHES...AN UNSTABLE SHOWERY AIRMASS WILL LEAD TO
PREDOMINANTLY VFR CONDITIONS THROUGH AT LEAST 06Z SATURDAY. A WARM
FRONT WILL SPREAD STEADY RAIN INTO THE TERMINAL BETWEEN 09Z AND
18Z SATURDAY. EXPECT A GRADUAL DETERIORATION TO MAINLY MVFR
CONDITIONS DURING THIS TIME. /NEUMAN

&&

.MARINE...THE MAIN WEATHER STORY IN THE IMMEDIATE SHORT TERM IS
THAT SEAS CURRENTLY IN THE 10 TO 12 FT RANGE WILL NEARLY DOUBLE IN
HEIGHT TODAY...RISING INTO THE 20 TO 23 FT RANGE WITH DOMINANT
PERIODS NEAR 18 SECONDS. ANY SMALL CRAFT VESSELS ARE URGED TO COME
ONSHORE IMMEDIATELY AS HIGHER SEAS ARE BEGINNING TO ARRIVE. BUOY
89 ABOUT 70 MILES OFFSHORE IS ALREADY REPORTING SEAS NEAR 15 FT
AT 8 AM...AND WILL LIKELY EXCEED 20 FT BY EARLY AFTERNOON.

PEOPLE SHOULD AVOID WALKING AND CLIMBING ON JETTIES ALONG THE
OREGON AND WASHINGTON COASTS THROUGH SATURDAY...BUT ESPECIALLY
THIS AFTERNOON AND EVENING. THERE IS CONSIDERABLE CONCERN THAT
SNEAKER WAVES WILL POSE A RISK TO THE GENERAL PUBLIC WALKING ALONG
THE BEACHES THIS AFTERNOON AND EVENING. THIS GENERAL PATTERN OF A
LARGE INCOMING SWELL OFTEN ALLOWS UNWARY BEACH GOERS TO BE CAUGHT
OFF GUARD BY WAVES THAT RUN MUCH FARTHER UP THE BEACH THAN WAVES
OVER THE PREVIOUS 15 TO 30 MINUTES. UNDER SIMILAR SCENARIOS IN THE
PAST...WAVES HAVE BEEN KNOWN TO KNOCK UNWARY PEOPLE AND PETS OFF
THEIR FEET BEFORE THE RECEDING WATER PULLS THEN BACK INTO THE SURF
ZONE. IN ADDITION...THESE HIGHER WAVES CAN CAUSE DRIFTWOOD THAT
APPEARS LOCKED IN PLACE ALONG THE BEACH TO BECOME MOBILE AND ROLL
OVER AN UNSUSPECTING PERSON. AGAIN...THIS HAPPENS NEARLY EVERY
YEAR ALONG THE OREGON COAST...AND THIS IS AN IDEAL SETUP FOR THESE
LARGE SNEAKER WAVES TO DO JUST THIS. PLEASE BE COGNIZANT OF THIS
WHEN RECREATING ON BEACHES TODAY AND TONIGHT.

THE NEXT FRONTAL STORM SYSTEM IS STILL ON TRACK TO IMPACT THE
WATERS LATE TONIGHT AND SATURDAY. EXPECT WINDS TO GRADUALLY
INCREASE TODAY AND TONIGHT...WITH SOLID GALE FORCE WINDS OF 30 TO
35 KT WITH GUSTS OF 40 TO 45 KT EXPECTED ACROSS THE WATERS BY
SATURDAY MORNING. THERE IS A CHANCE GUSTS MAY APPROACH 50 KT
WITHIN 20 NM OF THE COAST AS A SHORT LIVED COASTAL JET
DEVELOPS...ESPECIALLY ALONG THE CENTRAL OREGON COAST. WHILE THE
AFOREMENTIONED LARGE WESTERLY SWELL WILL BE SLOWLY TAPERING
SATURDAY...THIS RENEWED SHOT OF WINDS ACROSS THE WATERS...WILL
LIKELY KEEP SEAS FLIRTING WITH 20 FT FOR MUCH OF SATURDAY. EXPECT
THE HIGHEST WINDS TO TAPER AROUND MIDDAY OR EARLY SATURDAY
AFTERNOON. HOWEVER...ADDITIONAL GUSTS OF 35 KT MAY LINGER INTO
SATURDAY EVENING AS ANOTHER WEAK SURGE OF WINDS ENTERS THE WATERS.
OPTED TO EXTEND THE GALE WARNING INTO SATURDAY EVENING TO COVER
THIS PERIOD...BUT CONFIDENCE IS CONSIDERABLY LOWER THAT THESE 35
KT WIND GUSTS WILL OCCUR LATE SATURDAY AFTERNOON AND EVENING.
AGAIN...THE PRIMARY WINDOW FOR SOLID GALE FORCE WINDS WILL BE
SATURDAY MORNING AND CONFIDENCE IS HIGH.

WESTERLY WINDS WILL CONTINUE INTO SUNDAY...AND KEEP SEAS WELL INTO
THE TEENS THROUGH SUNDAY NIGHT. SEAS MAY TEMPORARILY BOTTOM OUT
NEAR 10 FT EARLY NEXT WEEK BEFORE A WEAK FRONT...AND ACCOMPANYING
LARGER SWELL SLIDES INTO THE WATERS TOWARDS MIDWEEK.

WILL CONTINUE TO INVESTIGATE WHETHER OR NOT A COASTAL FLOOD
ADVISORY FOR MINOR TIDAL OVERFLOW FLOODING WILL BE NECESSARY FOR
THE SOUTH WASHINGTON COAST CENTERED AROUND THE HIGH TIDE EXPECTED
TO OCCUR AT 11 AM SATURDAY. GIVEN THE WILLAPA AND NASELLE RIVER FLOWS
WILL BE WELL BELOW FLOOD STAGE...AND HIGH TIDE NEAR TOKE POINT IS
EXPECTED TO FLIRT WITH 11 FT WITH A TIDAL ANOMALY NEAR 1 FT...WE
ARE LEANING TOWARDS NOT ISSUING A COASTAL FLOOD ADVISORY FOR
SATURDAY. HOWEVER...A SIMILAR TIDE HEIGHT WILL OCCUR AROUND MIDDAY
SUNDAY. BY THIS TIME...FLOWS ON THE WILLAPA AND NASELLE RIVERS
WILL BE CONSIDERABLY HIGHER SO THERE IS AN INCREASED CONCERN THAT
MINOR TIDAL OVERFLOW FLOODING WILL OCCUR ALONG LOW LYING ROADS
AROUND RAYMOND...NASELLE AND THE WILLAPA BAY IN GENERAL IN
SOUTHWEST WASHINGTON. GIVEN WIDESPREAD COASTAL FLOODING IS NOT
EXPECTED...WE ARE OPTING TO NOT ISSUE A COASTAL FLOOD WATCH...AND
WILL LIKELY WAIT TO ISSUE THE ADVISORY UNTIL WE GATHER MORE GROUND
TRUTH DATA AND SUNDAY APPROACHES. THE PEAK TIME OF CONCERN ON
SUNDAY WILL BE FROM APPROXIMATELY 9 AM TO 3 PM. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES... OR...FLOOD WATCH FROM SATURDAY
     AFTERNOON THROUGH MONDAY AFTERNOON FOR CASCADE FOOTHILLS IN LANE
     COUNTY-CASCADES IN LANE COUNTY-CENTRAL COAST RANGE OF WESTERN
     OREGON-CENTRAL COLUMBIA RIVER GORGE-CENTRAL OREGON COAST-
     CENTRAL WILLAMETTE VALLEY-COAST RANGE OF NORTHWEST OREGON-
     GREATER PORTLAND METRO AREA-LOWER COLUMBIA-NORTH OREGON COAST-
     NORTHERN OREGON CASCADE FOOTHILLS-NORTHERN OREGON CASCADES-
     SOUTH WILLAMETTE VALLEY-UPPER HOOD RIVER VALLEY-WESTERN
     COLUMBIA RIVER GORGE.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

WA...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR
     CENTRAL COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-I-5
     CORRIDOR IN COWLITZ COUNTY-SOUTH WASHINGTON CASCADE
     FOOTHILLS-SOUTH WASHINGTON CASCADES-SOUTH WASHINGTON COAST-
     WESTERN COLUMBIA RIVER GORGE-WILLAPA HILLS.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR SOUTH WASHINGTON
     COAST.

     WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM PST
     SATURDAY FOR SOUTH WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 AM PST SATURDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     GALE WARNING FROM 1 AM TO 9 PM PST SATURDAY FOR COASTAL WATERS
     FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 AM PST SATURDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
     NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST
     SUNDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 191848
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1048 AM PST FRI DEC 19 2014

.SYNOPSIS...SCATTERED SHOWERS WILL CONTINUE TODAY WITH SNOW SHOWERS
IN THE CASCADES. MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND
WITH AN ATMOSPHERIC RIVER PATTERN RESULTING IN HEAVY RAIN ACROSS MUCH
OF THE REGION...ESPECIALLY MOUNTAINOUS TERRAIN. THERE IS THE
POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO EARLY NEXT WEEK.
LONGER RANGE MODEL OUTPUT IS SUGGESTING A COLDER AIR MASS WILL SETTLE
OVER THE PACIFIC NORTHWEST LATE NEXT WEEK.

&&

.MORNING UPDATE...UPPER TROUGH LOOKS LIKE IT HAS JUST PASSED THE AREA THIS
MORNING AND AS SUCH SHOWER ACTIVITY IS LESSENING. WILL SEE SOME
CLEARING THIS AFTERNOON WITH SCATTERED SHOWERS BEFORE CLOUDS AND THEN
STRATIFORM PRECIP FROM THE NEXT SYSTEM BEGIN TO MOVE INTO THE AREA
EARLY THIS EVENING.

THERE HAVE NOT BEEN ANY SIGNIFICANT CHANGES IN THE MODELS THIS
MORNING AND WE APPEAR TO REMAIN ON TRACK FOR A SIGNIFICANT
ATMOSPHERIC RIVER EVENT BEGINNING TONIGHT. COMPARED WITH
YESTERDAY...IT LOOKS LIKE MODELS ARE SHOWING A SLIGHTLY LATER ONSET
OF TRUE WESTERLY 850 MB FLOW...WHICH WOULD SOMEWHAT LIMIT THE
OROGRAPHIC ENHANCEMENT DURING THE BEGINNING OF THE EVENT...BUT THAT
SHOULD NOT CHANGE STORM TOTAL QPF VERY MUCH. HAVE ISSUED A FLOOD
WATCH FOR THE ENTIRE FORECAST AREA BASED ON FORECASTS OF FLOOD OR
NEAR FLOOD STAGE AT MANY RIVER POINTS IN THE AREA.

MODELS ARE INDICATING COLD AIR WILL HANG AROUND THE S WASHINGTON
CASCADES A BIT LONGER THAN ELSEWHERE AND SW FLOW TONIGHT WILL FAVOR
OROGRAPHIC ENHANCEMENT THERE...SO HAVE ISSUED A WINTER WEATHER
ADVISORY FOR AREAS ABOVE 3500 FT. COULD ALSO SEE SOME SNOW
ACCUMULATION ABOVE 4000 FT AROUND AND EAST OF MT HOOD INTO TOMORROW
MORNING...BUT WIDESPREAD AMOUNTS LOOKS LIKE THEY`LL REMAIN LESS THAN
6 INCHES DURING ANY GIVEN 6 HR PERIOD SO HAVE NOT ISSUED ANYTHING FOR
THAT AREA AT THIS TIME. BOWEN

.SHORT TERM (PREVIOUS DISCUSSION)....TODAY THROUGH SUNDAY...THE MAIN
WEATHER FEATURE TODAY WILL BE THE COLD UPPER TROUGH. LATEST
MODEL GUIDANCE SHOWS THE BULK OF THE TROUGH THROUGH THE AREA BY
MIDDAY. SNOW LEVELS DROP TO BELOW THE CASCADES PASSES TODAY...BUT THE
MAJORITY OF THE QPF HAS ALREADY OCCURRED. NAM MODEL SOUNDING FOR KAST
WOULD INDICATE THE BEST POTENTIAL FOR THUNDERSTORMS TO BE THROUGH THE
MORNING HOURS. NAM SOUNDING VALID 17Z TODAY SHOWS AN LI OF 0 WITH A
PRETTY HEFTY SWEAT INDEX OF 335...WELL ABOVE THE GENERALIZED 250
SWEAT INDEX BENCHMARK USED FOR ELEVATED CONVECTIVE
CONFIDENCE. THE CONVECTIVE POTENTIAL THEN DIMINISHES IN THE AFTERNOON
AS THE AIR MASS ALOFT STARTS TO STABILIZE.

THE BIGGER STORY CONTINUES TO BE THE ATMOSPHERIC RIVER EVENT OVER THE
WEEKEND. LATEST MODEL RUNS ARE GENERALLY CONSISTENT WITH THEIR
RESPECTIVE PAST RUNS WITH FAIRLY DECENT CONTINUITY AMONGST THE
INDIVIDUAL MODELS. THE MAIN FORECAST ISSUES WILL BE THE FOCUS OF THE
HEAVIEST PRECIP AND THE DURATION. GFS HAS BEEN PERSISTENT IN
DIRECTING THE BAROCLINIC BAND OVER EXTREME SW WA AND NRN OREGON. THE
NAM AND ECMWF ARE FAIRLY SIMILAR...BUT THE ECMWF SEEMS TO FOCUS THE
HEAVIEST QPF OVER THE CENTRAL PART OF THE FORECAST AREA 12Z SUN
THROUGH 00Z MON. THE 00Z WRF-GFS 48-HR QPF TOTALS VALID 12Z SAT
THROUGH 12Z MON SHOW AT LEAST 3-6 INCHES FOR THE OREGON CASCADES AND
2-4 INCHES FOR THE OREGON COAST RANGE. IT HAS LOWER AMOUNTS IN THE S
WA CASCADES AND WILLAPA HILLS. GFS AND NAM HAVE STRONG ISENTROPIC
LIFT ALONG THE 290K SURFACE STARTING 12Z SAT AND CONTINUING THROUGH
SUN. 850 MB WLY FLOW OF 40-50 KT INTO THE OREGON COAST RANGE AND
CASCADES SAT THROUGH SUN WILL RESULT IN A HIGHLY EFFICIENT OROGRAPHIC
RAINFALL COMPONENT. LOOKING AT THE ENSEMBLE SITUATIONAL AWARENESS
TABLE...SPECIFICALLY THE ENSEMBLE MODEL CLIMATE QPF (OR M CLIMATE
QPF)...IT INDICATES A 99TH PERCENTILE OR MAX QPF EVENT FOR A GOOD
PORTION OF THE OREGON CASCADES SAT AFTERNOON THROUGH SUN MORNING.
THIS MEANS THAT THE GEFS ENSEMBLE IS FORECASTING AN INORDINATE AMOUNT
OF PRECIP COMPARED TO THE 1985-2012 WINTER ENSEMBLE MODEL CLIMATE.
WOULD NOT BE SURPRISED TO SEE 1.5 TO 2.0 INCHES PER SIX HOURS IN THE
CASCADES FOR A 12-18 PERIOD. FORTUNATELY...THERE IS NO LOW-ELEVATION
SNOW AND MINIMAL SNOW AT PASS LEVELS. HOWEVER...LATEST HYDRO GUIDANCE
SUGGESTS A FEW RIVERS WILL REACH FLOOD STAGE BY SUN OR MON. REFER TO
THE HYDROLOGY SECTION FOR MORE DETAILS.

DO NOT ANTICIPATE HIGH WIND HIGHLIGHTS FOR THE COASTAL AREAS BUT IT
WILL BE RATHER BLUSTERY. THE NAM INDICATES A KAST-KOTH GRADIENT OF
AROUND 10 MB BY LATE SAT AFTERNOON AND IN THE EVENING. THE BENCHMARK
GRADIENT IS AROUND 12 MB. EXPECT 45-55 MPH GUSTS ALONG THE BEACHES
AND HEADLANDS SAT THROUGH SAT NIGHT.

IN ADDITION...THOSE PLANNING TO BE ALONG THE COAST AT AREA BEACHES
SHOULD CLOSELY MONITOR THE CONDITIONS THIS WEEKEND. RAPIDLY BUILDING
SEAS WILL BRING THE POTENTIAL FOR DANGEROUS HIGH SURF ALONG THE
BEACHES AS EARLY AS TODAY. LONG PERIOD SWELLS MAY REACH SHORE AND
SURPRISE INDIVIDUALS WHO ARE UNAWARE. ANYONE ON THE BEACHES SHOULD
EXERCISE EXTREME CAUTION AND AVOID THE SURF ZONE AS LARGE WAVES MAY
WASH OVER BEACHES AND JETTIES WITH LITTLE WARNING. SOME POTENTIAL FOR
MINOR TIDAL OVERFLOW IS POSSIBLE FOR SATURDAY AND SUNDAY...ESPECIALLY
AROUND HIGH TIDES. THIS THREAT COULD BE ENHANCED BY HIGH FLOWS ON
RIVERS IN RESPONSE TO THE RAINFALL THIS WEEKEND.  WEISHAAR

&&

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...MODELS AGREE THE WEEKEND
ATMOSPHERIC RIVER EVENT WILL WIND DOWN SUNDAY NIGHT INTO MONDAY.
UPPER RIDGING AMPLIFIES MON...BUT THIS WILL LIKELY BE A DIRTY RIDGE
AS THE GFS AND ECMWF HOLD ON TO SOME QPF...ESPECIALLY ACROSS THE NRN
HALF OF THE FORECAST AREA. HAVE ADJUSTED POPS TO REFLECT THIS
THINKING. A WEAK WARM FRONT MAY BRUSH THE NRN ZONES MON NIGHT AND TUE
FOR SOME ADDITIONAL PRECIP. THE GFS AND ECMWF THEN BRING A COLDER
UPPER LEVEL TROUGH ACROSS THE AREA WED. THE ECMWF DROPS 1000-500 MB
THICKNESS VALUES TO NEAR 530 DM 00Z THU WITH A DECENT AMOUNT OF QPF.
THUS...THE CASCADES AND SKI AREAS MAY FINALLY GET A DECENT SHOT OF
SNOW. COLDER NORTH FLOW WILL FOLLOW AND ALLOW TEMPERATURES TO COOL
WELL BELOW NORMAL AS CONDITIONS DRY OUT LATE WEEK. WEISHAAR

&&

.HYDROLOGY...SITUATION SETTING UP FOR A MEMORABLE HYDROLOGIC EVENT
MAINLY FOR LATER THIS WEEKEND AND HEADING INTO NEXT WEEK. STRONG AND
DEEP MOIST WESTERLY FLOW WILL BEGIN CROSSING THE PACNW COAST COME
SATURDAY MORNING. A VERY LONG FETCH OF MOISTURE IS STRETCHING ACROSS
THE PACIFIC WITH ORIGINS WEST TO THE SOUTH CHINA SEA. THIS MOIST AIR
MASS WILL BE PUSHED EAST BY A 150 TO 170 KT JET AND WESTERLY 25 TO
50 KT LOWER LEVEL WINDS. AS SUCH...THIS CONTINUES TO GIVE THE
APPEARANCE OF A CLASSIC HIGH PRECIPITATION ATMOSPHERIC RIVER EVENT
WHERE THE DEEP MOIST FLOW WILL SPEND A SIGNIFICANT AMOUNT OF TIME
ON A NEARLY PERPENDICULAR COURSE AGAINST THE COAST RANGE WITH THE
CASCADES TAKING A BIT HIGHER OF THE IMPACT. AS OF THE MORNING MODEL
RUNS AND RECENT NWRFC UPDATES...IT APPEARS MULTIPLE RIVERS HAVE
POTENTIAL OF EXCEEDING FLOOD STAGE. ADDITIONALLY...THIS EVENT HAS
SUFFICIENT DEPTH TO BRING SIGNIFICANT RAINS TO THE NORTH OREGON AND
SOUTH WASHINGTON CASCADES WHERE RIVERS WILL ALSO SEE POTENTIAL FOR
NOTABLE FLOODING. HAVE ISSUED FLOOD WATCH FOR THE ENTIRE FORECAST
AREA. KEEP IN MIND THAT DETAILS WILL ALWAYS BE IN FLUX UNDER THESE
SCENARIOS AS SUBTLE NORTH/SOUTH SHIFTS COLD MAKE DRAMATIC DIFFERENCES
IN WHICH BASINS RECEIVE EXTENDED PERIODS OF MODERATE TO HEAVY RAIN.
PLEASE CONTINUE TO FOLLOW THE LATEST FORECASTS AND IMPACTS AS
CONDITIONS WARRANT. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE).
JBONK/BOWEN

&&

.AVIATION...A SHOWERY AIRMASS WILL LEAD TO PREDOMINANTLY VFR
CONDITIONS THROUGH THIS EVENING. A WARM FRONT SPREADING WIDESPREAD
LIGHT TO MODERATE RAIN INTO THE AREA OVERNIGHT SHOULD RESULT IN
A DETERIORATION AT ALL TAF SITES AFTER 06Z SATURDAY. EXPECT
WIDESPREAD HIGH END IFR TO MAINLY MVFR CONDITIONS BETWEEN 09Z
AND 18Z SATURDAY.

KPDX AND APPROACHES...AN UNSTABLE SHOWERY AIRMASS WILL LEAD TO
PREDOMINANTLY VFR CONDITIONS THROUGH AT LEAST 06Z SATURDAY. A WARM
FRONT WILL SPREAD STEADY RAIN INTO THE TERMINAL BETWEEN 09Z AND
18Z SATURDAY. EXPECT A GRADUAL DETERIORATION TO MAINLY MVFR
CONDITIONS DURING THIS TIME. /NEUMAN

&&

.MARINE...THE MAIN WEATHER STORY IN THE IMMEDIATE SHORT TERM IS
THAT SEAS CURRENTLY IN THE 10 TO 12 FT RANGE WILL NEARLY DOUBLE IN
HEIGHT TODAY...RISING INTO THE 20 TO 23 FT RANGE WITH DOMINANT
PERIODS NEAR 18 SECONDS. ANY SMALL CRAFT VESSELS ARE URGED TO COME
ONSHORE IMMEDIATELY AS HIGHER SEAS ARE BEGINNING TO ARRIVE. BUOY
89 ABOUT 70 MILES OFFSHORE IS ALREADY REPORTING SEAS NEAR 15 FT
AT 8 AM...AND WILL LIKELY EXCEED 20 FT BY EARLY AFTERNOON.

PEOPLE SHOULD AVOID WALKING AND CLIMBING ON JETTIES ALONG THE
OREGON AND WASHINGTON COASTS THROUGH SATURDAY...BUT ESPECIALLY
THIS AFTERNOON AND EVENING. THERE IS CONSIDERABLE CONCERN THAT
SNEAKER WAVES WILL POSE A RISK TO THE GENERAL PUBLIC WALKING ALONG
THE BEACHES THIS AFTERNOON AND EVENING. THIS GENERAL PATTERN OF A
LARGE INCOMING SWELL OFTEN ALLOWS UNWARY BEACH GOERS TO BE CAUGHT
OFF GUARD BY WAVES THAT RUN MUCH FARTHER UP THE BEACH THAN WAVES
OVER THE PREVIOUS 15 TO 30 MINUTES. UNDER SIMILAR SCENARIOS IN THE
PAST...WAVES HAVE BEEN KNOWN TO KNOCK UNWARY PEOPLE AND PETS OFF
THEIR FEET BEFORE THE RECEDING WATER PULLS THEN BACK INTO THE SURF
ZONE. IN ADDITION...THESE HIGHER WAVES CAN CAUSE DRIFTWOOD THAT
APPEARS LOCKED IN PLACE ALONG THE BEACH TO BECOME MOBILE AND ROLL
OVER AN UNSUSPECTING PERSON. AGAIN...THIS HAPPENS NEARLY EVERY
YEAR ALONG THE OREGON COAST...AND THIS IS AN IDEAL SETUP FOR THESE
LARGE SNEAKER WAVES TO DO JUST THIS. PLEASE BE COGNIZANT OF THIS
WHEN RECREATING ON BEACHES TODAY AND TONIGHT.

THE NEXT FRONTAL STORM SYSTEM IS STILL ON TRACK TO IMPACT THE
WATERS LATE TONIGHT AND SATURDAY. EXPECT WINDS TO GRADUALLY
INCREASE TODAY AND TONIGHT...WITH SOLID GALE FORCE WINDS OF 30 TO
35 KT WITH GUSTS OF 40 TO 45 KT EXPECTED ACROSS THE WATERS BY
SATURDAY MORNING. THERE IS A CHANCE GUSTS MAY APPROACH 50 KT
WITHIN 20 NM OF THE COAST AS A SHORT LIVED COASTAL JET
DEVELOPS...ESPECIALLY ALONG THE CENTRAL OREGON COAST. WHILE THE
AFOREMENTIONED LARGE WESTERLY SWELL WILL BE SLOWLY TAPERING
SATURDAY...THIS RENEWED SHOT OF WINDS ACROSS THE WATERS...WILL
LIKELY KEEP SEAS FLIRTING WITH 20 FT FOR MUCH OF SATURDAY. EXPECT
THE HIGHEST WINDS TO TAPER AROUND MIDDAY OR EARLY SATURDAY
AFTERNOON. HOWEVER...ADDITIONAL GUSTS OF 35 KT MAY LINGER INTO
SATURDAY EVENING AS ANOTHER WEAK SURGE OF WINDS ENTERS THE WATERS.
OPTED TO EXTEND THE GALE WARNING INTO SATURDAY EVENING TO COVER
THIS PERIOD...BUT CONFIDENCE IS CONSIDERABLY LOWER THAT THESE 35
KT WIND GUSTS WILL OCCUR LATE SATURDAY AFTERNOON AND EVENING.
AGAIN...THE PRIMARY WINDOW FOR SOLID GALE FORCE WINDS WILL BE
SATURDAY MORNING AND CONFIDENCE IS HIGH.

WESTERLY WINDS WILL CONTINUE INTO SUNDAY...AND KEEP SEAS WELL INTO
THE TEENS THROUGH SUNDAY NIGHT. SEAS MAY TEMPORARILY BOTTOM OUT
NEAR 10 FT EARLY NEXT WEEK BEFORE A WEAK FRONT...AND ACCOMPANYING
LARGER SWELL SLIDES INTO THE WATERS TOWARDS MIDWEEK.

WILL CONTINUE TO INVESTIGATE WHETHER OR NOT A COASTAL FLOOD
ADVISORY FOR MINOR TIDAL OVERFLOW FLOODING WILL BE NECESSARY FOR
THE SOUTH WASHINGTON COAST CENTERED AROUND THE HIGH TIDE EXPECTED
TO OCCUR AT 11 AM SATURDAY. GIVEN THE WILLAPA AND NASELLE RIVER FLOWS
WILL BE WELL BELOW FLOOD STAGE...AND HIGH TIDE NEAR TOKE POINT IS
EXPECTED TO FLIRT WITH 11 FT WITH A TIDAL ANOMALY NEAR 1 FT...WE
ARE LEANING TOWARDS NOT ISSUING A COASTAL FLOOD ADVISORY FOR
SATURDAY. HOWEVER...A SIMILAR TIDE HEIGHT WILL OCCUR AROUND MIDDAY
SUNDAY. BY THIS TIME...FLOWS ON THE WILLAPA AND NASELLE RIVERS
WILL BE CONSIDERABLY HIGHER SO THERE IS AN INCREASED CONCERN THAT
MINOR TIDAL OVERFLOW FLOODING WILL OCCUR ALONG LOW LYING ROADS
AROUND RAYMOND...NASELLE AND THE WILLAPA BAY IN GENERAL IN
SOUTHWEST WASHINGTON. GIVEN WIDESPREAD COASTAL FLOODING IS NOT
EXPECTED...WE ARE OPTING TO NOT ISSUE A COASTAL FLOOD WATCH...AND
WILL LIKELY WAIT TO ISSUE THE ADVISORY UNTIL WE GATHER MORE GROUND
TRUTH DATA AND SUNDAY APPROACHES. THE PEAK TIME OF CONCERN ON
SUNDAY WILL BE FROM APPROXIMATELY 9 AM TO 3 PM. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES... OR...FLOOD WATCH FROM SATURDAY
     AFTERNOON THROUGH MONDAY AFTERNOON FOR CASCADE FOOTHILLS IN LANE
     COUNTY-CASCADES IN LANE COUNTY-CENTRAL COAST RANGE OF WESTERN
     OREGON-CENTRAL COLUMBIA RIVER GORGE-CENTRAL OREGON COAST-
     CENTRAL WILLAMETTE VALLEY-COAST RANGE OF NORTHWEST OREGON-
     GREATER PORTLAND METRO AREA-LOWER COLUMBIA-NORTH OREGON COAST-
     NORTHERN OREGON CASCADE FOOTHILLS-NORTHERN OREGON CASCADES-
     SOUTH WILLAMETTE VALLEY-UPPER HOOD RIVER VALLEY-WESTERN
     COLUMBIA RIVER GORGE.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

WA...FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR
     CENTRAL COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-I-5
     CORRIDOR IN COWLITZ COUNTY-SOUTH WASHINGTON CASCADE
     FOOTHILLS-SOUTH WASHINGTON CASCADES-SOUTH WASHINGTON COAST-
     WESTERN COLUMBIA RIVER GORGE-WILLAPA HILLS.

     HIGH SURF ADVISORY UNTIL 4 PM PST SATURDAY FOR SOUTH WASHINGTON
     COAST.

     WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM PST
     SATURDAY FOR SOUTH WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 AM PST SATURDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     GALE WARNING FROM 1 AM TO 9 PM PST SATURDAY FOR COASTAL WATERS
     FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 AM PST SATURDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
     NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST
     SUNDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.





000
FXUS66 KPQR 191225
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
424 AM PST FRI DEC 19 2014

.SYNOPSIS...AN UPPER LEVEL TROUGH WILL MOVE ACROSS THE FORECAST AREA
TODAY...WHICH WILL LOWER SNOW LEVELS BELOW THE CASCADE PASSES. THERE
MAY BE ENOUGH INSTABILITY TODAY OVER THE COASTAL AREAS FOR A THREAT
OF THUNDERSTORMS. MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND
WITH AN ATMOSPHERIC RIVER PATTERN RESULTING IN HEAVY RAIN ACROSS MUCH
OF THE REGION...ESPECIALLY MOUNTAINOUS TERRAIN. THE EXACT LOCATION OF
THE JET STREAM AND ASSOCIATED MOISTURE PLUME IS STILL IN
QUESTION...BUT THERE IS INCREASING CONFIDENCE THAT IT WILL TAKE AIM
AT SW WASHINGTON AND NW OREGON. THERE IS THE POTENTIAL FOR SOME
FLOODING LATE THIS WEEKEND INTO EARLY NEXT WEEK. LONGER RANGE MODEL
OUTPUT IS SUGGESTING A COLDER AIR MASS WILL SETTLE OVER THE PACIFIC
NORTHWEST LATE NEXT WEEK.

&&

.SHORT TERM....TODAY THROUGH SUNDAY...NWS KRTX DUAL-POL DOPPLER RADAR
AS OF 10Z SHOWS THE BACK EDGE OF THE FRONT MOVING ACROSS THE
CASCADES. SIX-HOUR RAINFALL AMOUNTS THROUGH 10Z WERE NOT ALL THAT
IMPRESSIVE...GENERALLY A QUARTER TO TWO-THIRDS OF AN INCH IN MOST
AREAS. RADAR AND INFRA-RED SATELLITE IMAGERY SHOW SHOWERS WITHIN THE
POST-FRONTAL COLDER AIR MASS ALREADY MOVING ONSHORE AND INTO THE
OREGON COAST RANGE AND SW WA WILLAPA HILLS. LIGHTNING DETECTION JUST
BEFORE 10Z INDICATED A POSITIVE STRIKE ALONG THE CENTRAL WA COAST.
JUST BEFORE 11Z A COUPLE STRIKES WERE NOTED NEAR FLORENCE.

THE MAIN WEATHER FEATURE TODAY WILL BE THE COLD UPPER TROUGH. LATEST
MODEL GUIDANCE SHOWS THE BULK OF THE TROUGH THROUGH THE AREA BY
MIDDAY. SNOW LEVELS DROP TO BELOW THE CASCADES PASSES TODAY...BUT THE
MAJORITY OF THE QPF HAS ALREADY OCCURRED. OROGRAPHIC ENHANCEMENT WILL
GIVE SOME SNOW TO THE CASCADES BUT UNDER ADVISORY CRITERIA. NAM MODEL
SOUNDING FOR KAST WOULD INDICATE THE BEST POTENTIAL FOR THUNDERSTORMS
TO BE THROUGH THE MORNING HOURS. NAM SOUNDING VALID 17Z TODAY SHOWS
AN LI OF 0 WITH A PRETTY HEFTY SWEAT INDEX OF 335...WELL ABOVE THE
GENERALIZED 250 SWEAT INDEX BENCHMARK USED FOR ELEVATED CONVECTIVE
CONFIDENCE. THE CONVECTIVE POTENTIAL THEN DIMINISHES IN THE AFTERNOON
AS THE AIR MASS ALOFT STARTS TO STABILIZE.

THE BIGGER STORY CONTINUES TO BE THE ATMOSPHERIC RIVER EVENT OVER THE
WEEKEND. LATEST MODEL RUNS ARE GENERALLY CONSISTENT WITH THEIR
RESPECTIVE PAST RUNS WITH FAIRLY DECENT CONTINUITY AMONGST THE
INDIVIDUAL MODELS. THE MAIN FORECAST ISSUES WILL BE THE FOCUS OF THE
HEAVIEST PRECIP AND THE DURATION. GFS HAS BEEN PERSISTENT IN
DIRECTING THE BAROCLINIC BAND OVER EXTREME SW WA AND NRN OREGON. THE
NAM AND ECMWF ARE FAIRLY SIMILAR...BUT THE ECMWF SEEMS TO FOCUS THE
HEAVIEST QPF OVER THE CENTRAL PART OF THE FORECAST AREA 12Z SUN
THROUGH 00Z MON. THE 00Z WRF-GFS 48-HR QPF TOTALS VALID 12Z SAT
THROUGH 12Z MON SHOW AT LEAST 3-6 INCHES FOR THE OREGON CASCADES AND
2-4 INCHES FOR THE OREGON COAST RANGE. IT HAS LOWER AMOUNTS IN THE S
WA CASCADES AND WILLAPA HILLS. GFS AND NAM HAVE STRONG ISENTROPIC
LIFT ALONG THE 290K SURFACE STARTING 12Z SAT AND CONTINUING THROUGH
SUN. 850 MB WLY FLOW OF 40-50 KT INTO THE OREGON COAST RANGE AND
CASCADES SAT THROUGH SUN WILL RESULT IN A HIGHLY EFFECIENT OROGRAPHIC
RAINFALL COMPONENT. LOOKING AT THE ENSEMBLE SITUATIONAL AWARENESS
TABLE...SPECIFICALLY THE ENSEMBLE MODEL CLIMATE QPF (OR M CLIMATE
QPF)...IT INDICATES A 99TH PERCENTILE OR MAX QPF EVENT FOR A GOOD
PORTION OF THE OREGON CASCADES SAT AFTERNOON THROUGH SUN MORNING.
THIS MEANS THAT THE GEFS ENSEMBLE IS FORECASTING AN INORDINATE AMOUNT
OF PRECIP COMPARED TO THE 1985-2012 WINTER ENSEMBLE MODEL CLIMATE.
WOULD NOT BE SURPRISED TO SEE 1.5 TO 2.0 INCHES PER SIX HOURS IN THE
CASCADES FOR A 12-18 PERIOD. FORTUNATELY...THERE IS NO LOW-ELEVATION
SNOW AND MINIMAL SNOW AT PASS LEVELS. HOWEVER...LATEST HYDRO GUIDANCE
SUGGESTS A FEW RIVERS WILL REACH FLOOD STAGE BY SUN OR MON. REFER TO
THE HYDROLOGY SECTION FOR MORE DETAILS.

DO NOT ANTICIPATE HIGH WIND HIGHLIGHTS FOR THE COASTAL AREAS BUT IT
WILL BE RATHER BLUSTERY. THE NAM INDICATES A KAST-KOTH GRADIENT OF
AROUND 10 MB BY LATE SAT AFTERNOON AND IN THE EVENING. THE BENCHMARK
GRADIENT IS AROUND 12 MB. EXPECT 45-55 MPH GUSTS ALONG THE BEACHES
AND HEADLANDS SAT THROUGH SAT NIGHT.

IN ADDITION...THOSE PLANNING TO BE ALONG THE COAST AT AREA BEACHES
SHOULD CLOSELY MONITOR THE CONDITIONS THIS WEEKEND. RAPIDLY BUILDING
SEAS WILL BRING THE POTENTIAL FOR DANGEROUS HIGH SURF ALONG THE
BEACHES AS EARLY AS TODAY. LONG PERIOD SWELLS MAY REACH SHORE AND
SURPRISE INDIVIDUALS WHO ARE UNAWARE. ANYONE ON THE BEACHES SHOULD
EXERCISE EXTREME CAUTION AND AVOID THE SURF ZONE AS LARGE WAVES MAY
WASH OVER BEACHES AND JETTIES WITH LITTLE WARNING. SOME POTENTIAL FOR
MINOR TIDAL OVERFLOW IS POSSIBLE FOR SATURDAY AND SUNDAY...ESPECIALLY
AROUND HIGH TIDES. THIS THREAT COULD BE ENHANCED BY HIGH FLOWS ON
RIVERS IN RESPONSE TO THE RAINFALL THIS WEEKEND.  WEISHAAR

&&

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...MODELS AGREE THE WEEKEND
ATMOSPHERIC RIVER EVENT WILL WIND DOWN SUNDAY NIGHT INTO MONDAY.
UPPER RIDGING AMPLIFIES MON...BUT THIS WILL LIKELY BE A DIRTY RIDGE
AS THE GFS AND ECMWF HOLD ON TO SOME QPF...ESPECIALLY ACROSS THE NRN
HALF OF THE FORCAST AREA. HAVE ADJUSTED POPS TO REFLECT THIS
THINKING. A WEAK WARM FRONT MAY BRUSH THE NRN ZONES MON NIGHT AND TUE
FOR SOME ADDITIONAL PRECIP. THE GFS AND ECMWF THEN BRING A COLDER
UPPER LEVEL TROUGH ACROSS THE AREA WED. THE ECMWF DROPS 1000-500 MB
THICKNESS VALUES TO NEAR 530 DM 00Z THU WITH A DECENT AMOUNT OF QPF.
THUS...THE CASCADES AND SKI AREAS MAY FINALLY GET A DECENT SHOT OF
SNOW. COLDER NORTH FLOW WILL FOLLOW AND ALLOW TEMPERATURES TO COOL
WELL BELOW NORMAL AS CONDITIONS DRY OUT LATE WEEK. WEISHAAR

&&

.HYDROLOGY...SITUATION SETTING UP FOR A MEMORABLE HYDROLOGIC EVENT
MAINLY FOR LATER THIS WEEKEND AND HEADING INTO NEXT WEEK. STRONG AND
DEEP MOIST WESTERLY FLOW WILL BEGIN CROSSING THE PACNW COAST COME
SATURDAY MORNING. A VERY LONG FETCH OF MOISTURE IS STRETCHING ACROSS
THE PACIFIC WITH ORIGINS WEST TO THE SOUTH CHINA SEA. THIS MOIST AIR
MASS WILL BE PUSHED EAST BY A 150 TO 170 KT JET AND WESTERLY 25 TO
50 KT LOWER LEVEL WINDS. AS SUCH...THIS CONTINUES TO GIVE THE
APPEARANCE OF A CLASSIC HIGH PRECIPITATION ATMOSPHERIC RIVER EVENT
WHERE THE DEEP MOIST FLOW WILL SPEND A SIGNIFICANT AMOUNT OF TIME
ON A NEARLY PERPENDICULAR COURSE AGAINST THE COAST RANGE WITH THE
CASCADES TAKING A BIT HIGHER OF THE IMPACT. AS OF THE MORNING MODEL
RUNS AND RECENT NWRFC UPDATES...IT APPEARS MULTIPLE COAST RANGE
RIVERS HAVE A MODERATE POTENTIAL OF EXCEEDING FLOOD STAGE.
ADDITIONALLY...THIS EVENT HAS SUFFICIENT DEPTH TO BRING SIGNIFICANT
RAINS TO THE NORTH OREGON AND SOUTH WASHINGTON CASCADES WHERE RIVERS
WILL ALSO SEE POTENTIAL FOR NOTABLE FLOODING. WILL CONTINUE THE
HYDROLOGIC OUTLOOK (PDXESFPQR) PRODUCT HIGHLIGHTING CONCERNS. KEEP
IN MIND THAT DETAILS WILL ALWAYS BE IN FLUX UNDER THESE SCENARIOS AS
SUBTLE NORTH/SOUTH SHIFTS COLD MAKE DRAMATIC DIFFERENCES IN WHICH
BASINS RECEIVE EXTENDED PERIODS OF MODERATE TO HEAVY RAIN. PLEASE
CONTINUE TO FOLLOW THE LATEST FORECASTS AND IMPACTS AS CONDITIONS
WARRANT. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE)

/JBONK

&&
&&


.AVIATION...VFR CONDITIONS WILL PERSIST AT MOST TAF SITES
THROUGH THIS EVENING. HOWEVER...BRIEF PERIODS OF MVFR CIGS AND
VIS ARE POSSIBLE UNDER SHOWERY CONDITIONS. DUE TO AN UNSTABLE AIR
MASS OVER THE WATERS THERE REMAINS A CHANCE OF VCTS THROUGH AROUND
18Z TODAY FOR THE COASTAL TAF SITES. CONDITIONS WILL LIKELY BE A
MIX OF IFR TO VFR TONIGHT AND SAT AS A MUCH STRONGER FRONT PUSHES
ACROSS THE REGION. EXPECT THE FRONT TO APPROACH THE COAST AROUND
02Z...AND INLAND AFTER 05Z.

KPDX AND APPROACHES...VFR CONDITIONS TODAY AND TONIGHT.
HOWEVER...BRIEF PERIODS OF MVFR CIGS ARE POSSIBLE AS A FRONT
APPROACHES THE TERMINAL AFTER 05Z. /64

&&

.MARINE...THE SMALL CRAFT ADVISORY FOR WINDS AND HAZARDOUS SEAS
WAS EXTENDED TO LATE TONIGHT. EXPECT TO SEE CONTINUED GUSTS OF 25
KT OVER THE WATERS. SEAS ARE CURRENTLY RUNNING AROUND 12 FT AND
IS EXPECTED TO BUILD INTO THE MID TEENS THIS AFTERNOON. A STRONG
FRONT WILL MOVE ACROSS THE WATERS THIS EVENING AND TONIGHT. AS THE
FRONT APPROACHES THE WATERS WE CAN EXPECT THE SEAS TO CLIMB ABOVE
20 FT THIS EVENING WITH SOLID GALE GUSTS TO 45 KT EXPECTED AFTER
MIDNIGHT. AS SUCH...ISSUED A GALE WATCH STARTING LATE TONIGHT
THROUGH SATURDAY AFTERNOON. SEAS WILL SLOWLY SUBSIDE ON SATURDAY
AFTERNOON AND EVENING WITH WINDS RELAXING TO AROUND 25 KT
OVERNIGHT. THE ACTIVE WEATHER PATTERN CONTINUES INTO MONDAY.
HOWEVER...CONDITIONS WILL NOT BE AS INTENSE. /64

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH SURF ADVISORY FROM 10 AM THIS MORNING TO 4 PM PST SATURDAY
     FOR CENTRAL OREGON COAST-NORTH OREGON COAST.

WA...HIGH SURF ADVISORY FROM 10 AM THIS MORNING TO 4 PM PST SATURDAY
     FOR SOUTH WASHINGTON COAST.

PZ...GALE WATCH FROM LATE TONIGHT THROUGH SATURDAY AFTERNOON FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 AM PST SATURDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 AM PST SATURDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 6 PM
     PST SATURDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 190405
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
805 PM PST THU DEC 18 2014

.SYNOPSIS...A FRONTAL SYSTEM WILL PUSH ONSHORE LATER TONIGHT. A
COLDER UPPER TROUGH MOVES ACROSS THE AREA FRIDAY...WHICH WILL LOWER
SNOW LEVELS BELOW THE CASCADE PASSES. MILD AND VERY WET WEATHER IS
EXPECTED THIS WEEKEND WITH AN ATMOSPHERIC RIVER BRINGING HEAVY RAIN
TO THE REGION. THE EXACT LOCATION OF THE JET STREAM AND ASSOCIATED
MOISTURE PLUME IS STILL IN QUESTION...BUT THERE IS INCREASING
CONFIDENCE THAT IT WILL TAKE AIM AT SW WASHINGTON AND NW OREGON.
THERE IS THE POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO
EARLY NEXT WEEK.

&&

.SHORT TERM....FRONT HAVING PAST BUOY 46029 EARLY THIS EVENING
EXPECTED TO REACH THE SHORE AND BEGIN TO MOVE INLAND BY LATE
EVENING. FAIRLY SOLID BAND OF PRECIPITATION ACCOMPANIES THE FRONT ON
RADAR SO POPS WILL REMAIN HIGH EARLY TONIGHT UNTIL THE FRONT MOVES
THROUGH. POST FRONTAL SHOWERS EXPECTED TO PICK UP LATER IN THE
NIGHT AND EARLY FRI AS THE COLD UPPER TROUGH MOVES ACROSS.

REMAINDER OF SHORT TERM DISCUSSION UNCHANGED...SNOW LEVELS WILL
LOWER DOWN TO BELOW THE CASCADE PASSES BY EARLY FRIDAY MORNING AS
THE COLD UPPER TROUGH SLIDES OVER THE REGION. HOWEVER...THE BULK OF
THE PRECIPITATION WILL HAVE FINISHED BY THE TIME SNOW LEVELS COME
DOWN. OVERALL...A FEW INCHES OF SNOW AT THE PASSES ARE POSSIBLE WITH
A FEW ADDITIONAL INCHES OF SNOW AT THE HIGHER CASCADE ELEVATIONS.
ADDED A SLIGHT CHANCE OF THUNDERSTORMS TO THE FORECAST FOR THE COAST
RANGE AND POINTS WEST FOR EARLY TOMORROW MORNING. THE UPPER TROUGH
MOVES THROUGH THE AREA AND MODEL FORECAST SOUNDINGS INDICATE DECENT
INSTABILITY.

MODELS CONTINUE TO REMAIN IN GOOD AGREEMENT THAT A VERY MOIST
ATMOSPHERIC RIVER PATTERN WILL SET UP DIRECTING LARGE AMOUNTS OF
MOSITURE AT SW WASHINGTON AND NW OREGON THIS WEEKEND. HEAVY RAINFALL
LIKELY BEGINS BY EARLY SATURDAY MORNING AND CONTINUES THROUGH AT
LEAST SUNDAY. THE COAST RANGE...WILLAPA HILLS...CASCADES...AND
FOOTHILLS WILL LIKELY SEE ON THE ORDER OF 8 TO 12 INCHES OF RAINFALL.
LOCATIONS ON THE COAST MAY SEE 5 TO 7 INCHES OF RAIN...WHILE THE
INTERIOR VALLEY LOCATIONS CAN EXPECT 3 TO 4 INCHES. WHILE SOME
UNCERTAINTY IN THE PRECISE AREAS OF MAXIMUM RAINFALL
EXISTS...CONFIDENCE IS INCREASING THAT LARGE AMOUNTS OF PRECIPITATION
WILL OCCUR ACROSS THE FORECAST AREA WITH THIS SYSTEM. AS A
RESULT...THERE IS THE POTENTIAL FOR SHARP RISES ON AREA RIVERS AND
STREAMS THAT MAY RESULT IN FLOODING. SEE THE HYDROLOGY SECTION FOR
MORE DETAILS.

IN ADDITION...THOSE PLANNING TO BE ALONG THE COAST AT AREAS BEACHES
SHOULD CLOSELY MONITOR THE CONDITIONS FOR THIS WEEKEND. RAPIDLY
BUILDING SEAS WILL BRING THE POTENTIAL FOR DANGEROUS HIGH SURF ALONG
THE AREA BEACHES ON FRIDAY. LONG PERIOD SWELLS MAY REACH SHORE AND
SURPRISE INDIVIDUALS WHO ARE UNAWARE. ANYONE ON THE BEACHES SHOULD
EXERCISE EXTREME CAUTION AND AVOID THE SURF ZONE AS LARGE WAVES MAY
WASH OVER BEACHES AND JETTIES WITH LITTLE WARNING. SOME POTENTIAL FOR
MINOR TIDAL OVERFLOW IS POSSIBLE FOR SATURDAY AND SUNDAY...ESPECIALLY
AROUND HIGH TIDES. THIS THREAT COULD BE ENHANCED BY HIGH FLOWS ON
RIVERS IN RESPONSE TO THE RAINFALL THIS WEEKEND.  CULLEN

&&

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS. SUNDAY NIGHT
THROUGH THURSDAY...MODELS AGREE THE WEEKEND RAIN/FLOODING EVENT WILL
WIND DOWN SUNDAY NIGHT INTO MONDAY. A MUCH WEAKER FRONT MAY SLIDE
SOUTHWARD ACROSS NORTHWEST OREGON AND SOUTHWEST WASHINGTON MONDAY
NIGHT INTO TUESDAY. MODELS HAVE WAVERED A BIT ON THIS SYSTEM SO POPS
WERE GENERALLY KEPT IN THE HIGH END CHANCE TO LOW END LIKELY.
CONDITIONS SHOULD TEMPORARILY DRY OUT LATE TUESDAY BEFORE A COLDER
STORM SYSTEM BRINGS SHOWERS TO THE AREA ON WEDNESDAY...BUT
DISCREPANCIES CONTINUE AMONG THE MODELS. SNOW LEVELS WILL LIKELY
LOWER WELL BELOW PASS LEVEL SO HOLIDAY TRAVELERS HEADED OVER THE
CASCADE PASSES WILL CERTAINLY NEED TO MONITOR THE FORECAST. COLD
NORTHERLY WILL FOLLOW AND ALLOW TEMPERATURES TO COOL WELL BELOW
NORMAL AS CONDITIONS DRY OUT LATE WEEK. EASTERLY WINDS WILL LIKELY
RETURN. /NEUMAN

&&

.HYDROLOGY...SITUATION SETTING UP FOR A MEMORABLE HYDROLOGIC EVENT
MAINLY FOR LATER THIS WEEKEND AND HEADING INTO NEXT WEEK. STRONG AND
DEEP MOIST WESTERLY FLOW WILL BEGIN CROSSING THE PACNW COAST COME
SATURDAY MORNING. A VERY LONG FETCH OF MOISTURE IS STRETCHING ACROSS
THE PACIFIC WITH ORIGINS WEST TO THE SOUTH CHINA SEA. THIS MOIST AIR
MASS WILL BE PUSHED EAST BY A 150 TO 170 KT JET AND WESTERLY 25 TO
50 KT LOWER LEVEL WINDS. AS SUCH...THIS CONTINUES TO GIVE THE
APPEARANCE OF A CLASSIC HIGH PRECIPITATION ATMOSPHERIC RIVER EVENT
WHERE THE DEEP MOIST FLOW WILL SPEND A SIGNIFICANT AMOUNT OF TIME
ON A NEARLY PERPENDICULAR COURSE AGAINST THE COAST RANGE WITH THE
CASCADES TAKING A BIT HIGHER OF THE IMPACT. AS OF THE MORNING MODEL
RUNS AND RECENT NWRFC UPDATES...IT APPEARS MULTIPLE COAST RANGE
RIVERS HAVE A MODERATE POTENTIAL OF EXCEEDING FLOOD STAGE.
ADDITIONALLY...THIS EVENT HAS SUFFICIENT DEPTH TO BRING SIGNIFICANT
RAINS TO THE NORTH OREGON AND SOUTH WASHINGTON CASCADES WHERE RIVERS
WILL ALSO SEE POTENTIAL FOR NOTABLE FLOODING. WILL CONTINUE THE
HYDROLOGIC OUTLOOK (PDXESFPQR) PRODUCT HIGHLIGHTING CONCERNS. KEEP
IN MIND THAT DETAILS WILL ALWAYS BE IN FLUX UNDER THESE SCENARIOS AS
SUBTLE NORTH/SOUTH SHIFTS COLD MAKE DRAMATIC DIFFERENCES IN WHICH
BASINS RECEIVE EXTENDED PERIODS OF MODERATE TO HEAVY RAIN. PLEASE
CONTINUE TO FOLLOW THE LATEST FORECASTS AND IMPACTS AS CONDITIONS
WARRANT. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE)

/JBONK

&&

.AVIATION...MOSTLY LOW TO MID RANGE VFR ACROSS REGION...BUT DO
HAVE AREAS OF MVFR CIGS WITH RAIN OVER COAST RANGE AND ALONG
COAST THIS EVENING. THIS WILL PUSH INLAND THROUGH 08Z. FRONT NOW
JUST ONSHORE...AND WILL PUSH THE CASCADES BY 08Z. CONDITIONS
SLOWLY IMPROVE TO VFR WITH TRANSITION TO SHOWERS BEHIND THE FRONT.
WILL KEEP SLIGHT CHANCE OF TS ALONG THE COAST FOR LATER TONIGHT
AND INTO FRI AM. OTHERWISE...MOSTLY VFR ON FRI WITH POCKETS OF
MVFR CONDITIONS UNDER SHOWERS.

PDX AND APPROACHES...VFR THIS EVENING AND FRI. BUT WILL HAVE
PERIOD OF MVFR CIGS DOWN TO 2500 FT AS FRONT MOVES ACROSS REGION.
BEST TIMING SEEMS TO BE 07Z TO 12Z FOR SUCH CONDITIONS. OTHERWISE
NO SIGNIFICANT IMPACTS EXPECTED FOR OPS AREA.         ROCKEY.
&&

.MARINE...WITH FRONT JUST ONSHORE...WINDS HAVE NOW EASED.
GENERALLY GUSTING TO NEAR 25 KT. SO WILL REPLACE GALE WARNING WITH
SMALL CRAFT ADVISORIES FOR BOTH WINDS AND SEAS. BOTH ADVISORIES
WILL EXTEND THROUGH FRI NIGHT.

SEAS HOLDING AT 12 TO 14 FT TONIGHT BUT WILL DROP BACK A FEW FEET
FOR FRI. BUT WITH INCREASING WINDS LATER FRI NIGHT...SO SEAS WILL
BUILD. STILL LOOK LIKE BUILDING UP TO NEAR 20 FT BY LATE FRI
AFTERNOON...AND LIKELY AROUND 25 FT FRI NIGHT. WINDS AND SEAS WILL
EASE BACK LATER SAT NIGHT AND SUN.                    ROCKEY.
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH SURF ADVISORY FROM 10 AM FRIDAY TO 4 AM PST SATURDAY FOR
     CENTRAL OREGON COAST-NORTH OREGON COAST.

WA...HIGH SURF ADVISORY FROM 10 AM FRIDAY TO 4 AM PST SATURDAY FOR
     SOUTH WASHINGTON COAST.

PZ...SMALL CRAFT ADVISORY FOR BOTH WINDS AND HAZARDOUS SEAS FOR
         TONIGHT THROUGH FRI NIGHT.
     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS
         THROUGH FRI NIGHT.

&&


$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 190405
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
805 PM PST THU DEC 18 2014

.SYNOPSIS...A FRONTAL SYSTEM WILL PUSH ONSHORE LATER TONIGHT. A
COLDER UPPER TROUGH MOVES ACROSS THE AREA FRIDAY...WHICH WILL LOWER
SNOW LEVELS BELOW THE CASCADE PASSES. MILD AND VERY WET WEATHER IS
EXPECTED THIS WEEKEND WITH AN ATMOSPHERIC RIVER BRINGING HEAVY RAIN
TO THE REGION. THE EXACT LOCATION OF THE JET STREAM AND ASSOCIATED
MOISTURE PLUME IS STILL IN QUESTION...BUT THERE IS INCREASING
CONFIDENCE THAT IT WILL TAKE AIM AT SW WASHINGTON AND NW OREGON.
THERE IS THE POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO
EARLY NEXT WEEK.

&&

.SHORT TERM....FRONT HAVING PAST BUOY 46029 EARLY THIS EVENING
EXPECTED TO REACH THE SHORE AND BEGIN TO MOVE INLAND BY LATE
EVENING. FAIRLY SOLID BAND OF PRECIPITATION ACCOMPANIES THE FRONT ON
RADAR SO POPS WILL REMAIN HIGH EARLY TONIGHT UNTIL THE FRONT MOVES
THROUGH. POST FRONTAL SHOWERS EXPECTED TO PICK UP LATER IN THE
NIGHT AND EARLY FRI AS THE COLD UPPER TROUGH MOVES ACROSS.

REMAINDER OF SHORT TERM DISCUSSION UNCHANGED...SNOW LEVELS WILL
LOWER DOWN TO BELOW THE CASCADE PASSES BY EARLY FRIDAY MORNING AS
THE COLD UPPER TROUGH SLIDES OVER THE REGION. HOWEVER...THE BULK OF
THE PRECIPITATION WILL HAVE FINISHED BY THE TIME SNOW LEVELS COME
DOWN. OVERALL...A FEW INCHES OF SNOW AT THE PASSES ARE POSSIBLE WITH
A FEW ADDITIONAL INCHES OF SNOW AT THE HIGHER CASCADE ELEVATIONS.
ADDED A SLIGHT CHANCE OF THUNDERSTORMS TO THE FORECAST FOR THE COAST
RANGE AND POINTS WEST FOR EARLY TOMORROW MORNING. THE UPPER TROUGH
MOVES THROUGH THE AREA AND MODEL FORECAST SOUNDINGS INDICATE DECENT
INSTABILITY.

MODELS CONTINUE TO REMAIN IN GOOD AGREEMENT THAT A VERY MOIST
ATMOSPHERIC RIVER PATTERN WILL SET UP DIRECTING LARGE AMOUNTS OF
MOSITURE AT SW WASHINGTON AND NW OREGON THIS WEEKEND. HEAVY RAINFALL
LIKELY BEGINS BY EARLY SATURDAY MORNING AND CONTINUES THROUGH AT
LEAST SUNDAY. THE COAST RANGE...WILLAPA HILLS...CASCADES...AND
FOOTHILLS WILL LIKELY SEE ON THE ORDER OF 8 TO 12 INCHES OF RAINFALL.
LOCATIONS ON THE COAST MAY SEE 5 TO 7 INCHES OF RAIN...WHILE THE
INTERIOR VALLEY LOCATIONS CAN EXPECT 3 TO 4 INCHES. WHILE SOME
UNCERTAINTY IN THE PRECISE AREAS OF MAXIMUM RAINFALL
EXISTS...CONFIDENCE IS INCREASING THAT LARGE AMOUNTS OF PRECIPITATION
WILL OCCUR ACROSS THE FORECAST AREA WITH THIS SYSTEM. AS A
RESULT...THERE IS THE POTENTIAL FOR SHARP RISES ON AREA RIVERS AND
STREAMS THAT MAY RESULT IN FLOODING. SEE THE HYDROLOGY SECTION FOR
MORE DETAILS.

IN ADDITION...THOSE PLANNING TO BE ALONG THE COAST AT AREAS BEACHES
SHOULD CLOSELY MONITOR THE CONDITIONS FOR THIS WEEKEND. RAPIDLY
BUILDING SEAS WILL BRING THE POTENTIAL FOR DANGEROUS HIGH SURF ALONG
THE AREA BEACHES ON FRIDAY. LONG PERIOD SWELLS MAY REACH SHORE AND
SURPRISE INDIVIDUALS WHO ARE UNAWARE. ANYONE ON THE BEACHES SHOULD
EXERCISE EXTREME CAUTION AND AVOID THE SURF ZONE AS LARGE WAVES MAY
WASH OVER BEACHES AND JETTIES WITH LITTLE WARNING. SOME POTENTIAL FOR
MINOR TIDAL OVERFLOW IS POSSIBLE FOR SATURDAY AND SUNDAY...ESPECIALLY
AROUND HIGH TIDES. THIS THREAT COULD BE ENHANCED BY HIGH FLOWS ON
RIVERS IN RESPONSE TO THE RAINFALL THIS WEEKEND.  CULLEN

&&

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS. SUNDAY NIGHT
THROUGH THURSDAY...MODELS AGREE THE WEEKEND RAIN/FLOODING EVENT WILL
WIND DOWN SUNDAY NIGHT INTO MONDAY. A MUCH WEAKER FRONT MAY SLIDE
SOUTHWARD ACROSS NORTHWEST OREGON AND SOUTHWEST WASHINGTON MONDAY
NIGHT INTO TUESDAY. MODELS HAVE WAVERED A BIT ON THIS SYSTEM SO POPS
WERE GENERALLY KEPT IN THE HIGH END CHANCE TO LOW END LIKELY.
CONDITIONS SHOULD TEMPORARILY DRY OUT LATE TUESDAY BEFORE A COLDER
STORM SYSTEM BRINGS SHOWERS TO THE AREA ON WEDNESDAY...BUT
DISCREPANCIES CONTINUE AMONG THE MODELS. SNOW LEVELS WILL LIKELY
LOWER WELL BELOW PASS LEVEL SO HOLIDAY TRAVELERS HEADED OVER THE
CASCADE PASSES WILL CERTAINLY NEED TO MONITOR THE FORECAST. COLD
NORTHERLY WILL FOLLOW AND ALLOW TEMPERATURES TO COOL WELL BELOW
NORMAL AS CONDITIONS DRY OUT LATE WEEK. EASTERLY WINDS WILL LIKELY
RETURN. /NEUMAN

&&

.HYDROLOGY...SITUATION SETTING UP FOR A MEMORABLE HYDROLOGIC EVENT
MAINLY FOR LATER THIS WEEKEND AND HEADING INTO NEXT WEEK. STRONG AND
DEEP MOIST WESTERLY FLOW WILL BEGIN CROSSING THE PACNW COAST COME
SATURDAY MORNING. A VERY LONG FETCH OF MOISTURE IS STRETCHING ACROSS
THE PACIFIC WITH ORIGINS WEST TO THE SOUTH CHINA SEA. THIS MOIST AIR
MASS WILL BE PUSHED EAST BY A 150 TO 170 KT JET AND WESTERLY 25 TO
50 KT LOWER LEVEL WINDS. AS SUCH...THIS CONTINUES TO GIVE THE
APPEARANCE OF A CLASSIC HIGH PRECIPITATION ATMOSPHERIC RIVER EVENT
WHERE THE DEEP MOIST FLOW WILL SPEND A SIGNIFICANT AMOUNT OF TIME
ON A NEARLY PERPENDICULAR COURSE AGAINST THE COAST RANGE WITH THE
CASCADES TAKING A BIT HIGHER OF THE IMPACT. AS OF THE MORNING MODEL
RUNS AND RECENT NWRFC UPDATES...IT APPEARS MULTIPLE COAST RANGE
RIVERS HAVE A MODERATE POTENTIAL OF EXCEEDING FLOOD STAGE.
ADDITIONALLY...THIS EVENT HAS SUFFICIENT DEPTH TO BRING SIGNIFICANT
RAINS TO THE NORTH OREGON AND SOUTH WASHINGTON CASCADES WHERE RIVERS
WILL ALSO SEE POTENTIAL FOR NOTABLE FLOODING. WILL CONTINUE THE
HYDROLOGIC OUTLOOK (PDXESFPQR) PRODUCT HIGHLIGHTING CONCERNS. KEEP
IN MIND THAT DETAILS WILL ALWAYS BE IN FLUX UNDER THESE SCENARIOS AS
SUBTLE NORTH/SOUTH SHIFTS COLD MAKE DRAMATIC DIFFERENCES IN WHICH
BASINS RECEIVE EXTENDED PERIODS OF MODERATE TO HEAVY RAIN. PLEASE
CONTINUE TO FOLLOW THE LATEST FORECASTS AND IMPACTS AS CONDITIONS
WARRANT. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE)

/JBONK

&&

.AVIATION...MOSTLY LOW TO MID RANGE VFR ACROSS REGION...BUT DO
HAVE AREAS OF MVFR CIGS WITH RAIN OVER COAST RANGE AND ALONG
COAST THIS EVENING. THIS WILL PUSH INLAND THROUGH 08Z. FRONT NOW
JUST ONSHORE...AND WILL PUSH THE CASCADES BY 08Z. CONDITIONS
SLOWLY IMPROVE TO VFR WITH TRANSITION TO SHOWERS BEHIND THE FRONT.
WILL KEEP SLIGHT CHANCE OF TS ALONG THE COAST FOR LATER TONIGHT
AND INTO FRI AM. OTHERWISE...MOSTLY VFR ON FRI WITH POCKETS OF
MVFR CONDITIONS UNDER SHOWERS.

PDX AND APPROACHES...VFR THIS EVENING AND FRI. BUT WILL HAVE
PERIOD OF MVFR CIGS DOWN TO 2500 FT AS FRONT MOVES ACROSS REGION.
BEST TIMING SEEMS TO BE 07Z TO 12Z FOR SUCH CONDITIONS. OTHERWISE
NO SIGNIFICANT IMPACTS EXPECTED FOR OPS AREA.         ROCKEY.
&&

.MARINE...WITH FRONT JUST ONSHORE...WINDS HAVE NOW EASED.
GENERALLY GUSTING TO NEAR 25 KT. SO WILL REPLACE GALE WARNING WITH
SMALL CRAFT ADVISORIES FOR BOTH WINDS AND SEAS. BOTH ADVISORIES
WILL EXTEND THROUGH FRI NIGHT.

SEAS HOLDING AT 12 TO 14 FT TONIGHT BUT WILL DROP BACK A FEW FEET
FOR FRI. BUT WITH INCREASING WINDS LATER FRI NIGHT...SO SEAS WILL
BUILD. STILL LOOK LIKE BUILDING UP TO NEAR 20 FT BY LATE FRI
AFTERNOON...AND LIKELY AROUND 25 FT FRI NIGHT. WINDS AND SEAS WILL
EASE BACK LATER SAT NIGHT AND SUN.                    ROCKEY.
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH SURF ADVISORY FROM 10 AM FRIDAY TO 4 AM PST SATURDAY FOR
     CENTRAL OREGON COAST-NORTH OREGON COAST.

WA...HIGH SURF ADVISORY FROM 10 AM FRIDAY TO 4 AM PST SATURDAY FOR
     SOUTH WASHINGTON COAST.

PZ...SMALL CRAFT ADVISORY FOR BOTH WINDS AND HAZARDOUS SEAS FOR
         TONIGHT THROUGH FRI NIGHT.
     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS
         THROUGH FRI NIGHT.

&&


$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 190405
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
805 PM PST THU DEC 18 2014

.SYNOPSIS...A FRONTAL SYSTEM WILL PUSH ONSHORE LATER TONIGHT. A
COLDER UPPER TROUGH MOVES ACROSS THE AREA FRIDAY...WHICH WILL LOWER
SNOW LEVELS BELOW THE CASCADE PASSES. MILD AND VERY WET WEATHER IS
EXPECTED THIS WEEKEND WITH AN ATMOSPHERIC RIVER BRINGING HEAVY RAIN
TO THE REGION. THE EXACT LOCATION OF THE JET STREAM AND ASSOCIATED
MOISTURE PLUME IS STILL IN QUESTION...BUT THERE IS INCREASING
CONFIDENCE THAT IT WILL TAKE AIM AT SW WASHINGTON AND NW OREGON.
THERE IS THE POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO
EARLY NEXT WEEK.

&&

.SHORT TERM....FRONT HAVING PAST BUOY 46029 EARLY THIS EVENING
EXPECTED TO REACH THE SHORE AND BEGIN TO MOVE INLAND BY LATE
EVENING. FAIRLY SOLID BAND OF PRECIPITATION ACCOMPANIES THE FRONT ON
RADAR SO POPS WILL REMAIN HIGH EARLY TONIGHT UNTIL THE FRONT MOVES
THROUGH. POST FRONTAL SHOWERS EXPECTED TO PICK UP LATER IN THE
NIGHT AND EARLY FRI AS THE COLD UPPER TROUGH MOVES ACROSS.

REMAINDER OF SHORT TERM DISCUSSION UNCHANGED...SNOW LEVELS WILL
LOWER DOWN TO BELOW THE CASCADE PASSES BY EARLY FRIDAY MORNING AS
THE COLD UPPER TROUGH SLIDES OVER THE REGION. HOWEVER...THE BULK OF
THE PRECIPITATION WILL HAVE FINISHED BY THE TIME SNOW LEVELS COME
DOWN. OVERALL...A FEW INCHES OF SNOW AT THE PASSES ARE POSSIBLE WITH
A FEW ADDITIONAL INCHES OF SNOW AT THE HIGHER CASCADE ELEVATIONS.
ADDED A SLIGHT CHANCE OF THUNDERSTORMS TO THE FORECAST FOR THE COAST
RANGE AND POINTS WEST FOR EARLY TOMORROW MORNING. THE UPPER TROUGH
MOVES THROUGH THE AREA AND MODEL FORECAST SOUNDINGS INDICATE DECENT
INSTABILITY.

MODELS CONTINUE TO REMAIN IN GOOD AGREEMENT THAT A VERY MOIST
ATMOSPHERIC RIVER PATTERN WILL SET UP DIRECTING LARGE AMOUNTS OF
MOSITURE AT SW WASHINGTON AND NW OREGON THIS WEEKEND. HEAVY RAINFALL
LIKELY BEGINS BY EARLY SATURDAY MORNING AND CONTINUES THROUGH AT
LEAST SUNDAY. THE COAST RANGE...WILLAPA HILLS...CASCADES...AND
FOOTHILLS WILL LIKELY SEE ON THE ORDER OF 8 TO 12 INCHES OF RAINFALL.
LOCATIONS ON THE COAST MAY SEE 5 TO 7 INCHES OF RAIN...WHILE THE
INTERIOR VALLEY LOCATIONS CAN EXPECT 3 TO 4 INCHES. WHILE SOME
UNCERTAINTY IN THE PRECISE AREAS OF MAXIMUM RAINFALL
EXISTS...CONFIDENCE IS INCREASING THAT LARGE AMOUNTS OF PRECIPITATION
WILL OCCUR ACROSS THE FORECAST AREA WITH THIS SYSTEM. AS A
RESULT...THERE IS THE POTENTIAL FOR SHARP RISES ON AREA RIVERS AND
STREAMS THAT MAY RESULT IN FLOODING. SEE THE HYDROLOGY SECTION FOR
MORE DETAILS.

IN ADDITION...THOSE PLANNING TO BE ALONG THE COAST AT AREAS BEACHES
SHOULD CLOSELY MONITOR THE CONDITIONS FOR THIS WEEKEND. RAPIDLY
BUILDING SEAS WILL BRING THE POTENTIAL FOR DANGEROUS HIGH SURF ALONG
THE AREA BEACHES ON FRIDAY. LONG PERIOD SWELLS MAY REACH SHORE AND
SURPRISE INDIVIDUALS WHO ARE UNAWARE. ANYONE ON THE BEACHES SHOULD
EXERCISE EXTREME CAUTION AND AVOID THE SURF ZONE AS LARGE WAVES MAY
WASH OVER BEACHES AND JETTIES WITH LITTLE WARNING. SOME POTENTIAL FOR
MINOR TIDAL OVERFLOW IS POSSIBLE FOR SATURDAY AND SUNDAY...ESPECIALLY
AROUND HIGH TIDES. THIS THREAT COULD BE ENHANCED BY HIGH FLOWS ON
RIVERS IN RESPONSE TO THE RAINFALL THIS WEEKEND.  CULLEN

&&

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS. SUNDAY NIGHT
THROUGH THURSDAY...MODELS AGREE THE WEEKEND RAIN/FLOODING EVENT WILL
WIND DOWN SUNDAY NIGHT INTO MONDAY. A MUCH WEAKER FRONT MAY SLIDE
SOUTHWARD ACROSS NORTHWEST OREGON AND SOUTHWEST WASHINGTON MONDAY
NIGHT INTO TUESDAY. MODELS HAVE WAVERED A BIT ON THIS SYSTEM SO POPS
WERE GENERALLY KEPT IN THE HIGH END CHANCE TO LOW END LIKELY.
CONDITIONS SHOULD TEMPORARILY DRY OUT LATE TUESDAY BEFORE A COLDER
STORM SYSTEM BRINGS SHOWERS TO THE AREA ON WEDNESDAY...BUT
DISCREPANCIES CONTINUE AMONG THE MODELS. SNOW LEVELS WILL LIKELY
LOWER WELL BELOW PASS LEVEL SO HOLIDAY TRAVELERS HEADED OVER THE
CASCADE PASSES WILL CERTAINLY NEED TO MONITOR THE FORECAST. COLD
NORTHERLY WILL FOLLOW AND ALLOW TEMPERATURES TO COOL WELL BELOW
NORMAL AS CONDITIONS DRY OUT LATE WEEK. EASTERLY WINDS WILL LIKELY
RETURN. /NEUMAN

&&

.HYDROLOGY...SITUATION SETTING UP FOR A MEMORABLE HYDROLOGIC EVENT
MAINLY FOR LATER THIS WEEKEND AND HEADING INTO NEXT WEEK. STRONG AND
DEEP MOIST WESTERLY FLOW WILL BEGIN CROSSING THE PACNW COAST COME
SATURDAY MORNING. A VERY LONG FETCH OF MOISTURE IS STRETCHING ACROSS
THE PACIFIC WITH ORIGINS WEST TO THE SOUTH CHINA SEA. THIS MOIST AIR
MASS WILL BE PUSHED EAST BY A 150 TO 170 KT JET AND WESTERLY 25 TO
50 KT LOWER LEVEL WINDS. AS SUCH...THIS CONTINUES TO GIVE THE
APPEARANCE OF A CLASSIC HIGH PRECIPITATION ATMOSPHERIC RIVER EVENT
WHERE THE DEEP MOIST FLOW WILL SPEND A SIGNIFICANT AMOUNT OF TIME
ON A NEARLY PERPENDICULAR COURSE AGAINST THE COAST RANGE WITH THE
CASCADES TAKING A BIT HIGHER OF THE IMPACT. AS OF THE MORNING MODEL
RUNS AND RECENT NWRFC UPDATES...IT APPEARS MULTIPLE COAST RANGE
RIVERS HAVE A MODERATE POTENTIAL OF EXCEEDING FLOOD STAGE.
ADDITIONALLY...THIS EVENT HAS SUFFICIENT DEPTH TO BRING SIGNIFICANT
RAINS TO THE NORTH OREGON AND SOUTH WASHINGTON CASCADES WHERE RIVERS
WILL ALSO SEE POTENTIAL FOR NOTABLE FLOODING. WILL CONTINUE THE
HYDROLOGIC OUTLOOK (PDXESFPQR) PRODUCT HIGHLIGHTING CONCERNS. KEEP
IN MIND THAT DETAILS WILL ALWAYS BE IN FLUX UNDER THESE SCENARIOS AS
SUBTLE NORTH/SOUTH SHIFTS COLD MAKE DRAMATIC DIFFERENCES IN WHICH
BASINS RECEIVE EXTENDED PERIODS OF MODERATE TO HEAVY RAIN. PLEASE
CONTINUE TO FOLLOW THE LATEST FORECASTS AND IMPACTS AS CONDITIONS
WARRANT. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE)

/JBONK

&&

.AVIATION...MOSTLY LOW TO MID RANGE VFR ACROSS REGION...BUT DO
HAVE AREAS OF MVFR CIGS WITH RAIN OVER COAST RANGE AND ALONG
COAST THIS EVENING. THIS WILL PUSH INLAND THROUGH 08Z. FRONT NOW
JUST ONSHORE...AND WILL PUSH THE CASCADES BY 08Z. CONDITIONS
SLOWLY IMPROVE TO VFR WITH TRANSITION TO SHOWERS BEHIND THE FRONT.
WILL KEEP SLIGHT CHANCE OF TS ALONG THE COAST FOR LATER TONIGHT
AND INTO FRI AM. OTHERWISE...MOSTLY VFR ON FRI WITH POCKETS OF
MVFR CONDITIONS UNDER SHOWERS.

PDX AND APPROACHES...VFR THIS EVENING AND FRI. BUT WILL HAVE
PERIOD OF MVFR CIGS DOWN TO 2500 FT AS FRONT MOVES ACROSS REGION.
BEST TIMING SEEMS TO BE 07Z TO 12Z FOR SUCH CONDITIONS. OTHERWISE
NO SIGNIFICANT IMPACTS EXPECTED FOR OPS AREA.         ROCKEY.
&&

.MARINE...WITH FRONT JUST ONSHORE...WINDS HAVE NOW EASED.
GENERALLY GUSTING TO NEAR 25 KT. SO WILL REPLACE GALE WARNING WITH
SMALL CRAFT ADVISORIES FOR BOTH WINDS AND SEAS. BOTH ADVISORIES
WILL EXTEND THROUGH FRI NIGHT.

SEAS HOLDING AT 12 TO 14 FT TONIGHT BUT WILL DROP BACK A FEW FEET
FOR FRI. BUT WITH INCREASING WINDS LATER FRI NIGHT...SO SEAS WILL
BUILD. STILL LOOK LIKE BUILDING UP TO NEAR 20 FT BY LATE FRI
AFTERNOON...AND LIKELY AROUND 25 FT FRI NIGHT. WINDS AND SEAS WILL
EASE BACK LATER SAT NIGHT AND SUN.                    ROCKEY.
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH SURF ADVISORY FROM 10 AM FRIDAY TO 4 AM PST SATURDAY FOR
     CENTRAL OREGON COAST-NORTH OREGON COAST.

WA...HIGH SURF ADVISORY FROM 10 AM FRIDAY TO 4 AM PST SATURDAY FOR
     SOUTH WASHINGTON COAST.

PZ...SMALL CRAFT ADVISORY FOR BOTH WINDS AND HAZARDOUS SEAS FOR
         TONIGHT THROUGH FRI NIGHT.
     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS
         THROUGH FRI NIGHT.

&&


$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.





000
FXUS66 KPQR 190405
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
805 PM PST THU DEC 18 2014

.SYNOPSIS...A FRONTAL SYSTEM WILL PUSH ONSHORE LATER TONIGHT. A
COLDER UPPER TROUGH MOVES ACROSS THE AREA FRIDAY...WHICH WILL LOWER
SNOW LEVELS BELOW THE CASCADE PASSES. MILD AND VERY WET WEATHER IS
EXPECTED THIS WEEKEND WITH AN ATMOSPHERIC RIVER BRINGING HEAVY RAIN
TO THE REGION. THE EXACT LOCATION OF THE JET STREAM AND ASSOCIATED
MOISTURE PLUME IS STILL IN QUESTION...BUT THERE IS INCREASING
CONFIDENCE THAT IT WILL TAKE AIM AT SW WASHINGTON AND NW OREGON.
THERE IS THE POTENTIAL FOR SOME FLOODING LATE THIS WEEKEND INTO
EARLY NEXT WEEK.

&&

.SHORT TERM....FRONT HAVING PAST BUOY 46029 EARLY THIS EVENING
EXPECTED TO REACH THE SHORE AND BEGIN TO MOVE INLAND BY LATE
EVENING. FAIRLY SOLID BAND OF PRECIPITATION ACCOMPANIES THE FRONT ON
RADAR SO POPS WILL REMAIN HIGH EARLY TONIGHT UNTIL THE FRONT MOVES
THROUGH. POST FRONTAL SHOWERS EXPECTED TO PICK UP LATER IN THE
NIGHT AND EARLY FRI AS THE COLD UPPER TROUGH MOVES ACROSS.

REMAINDER OF SHORT TERM DISCUSSION UNCHANGED...SNOW LEVELS WILL
LOWER DOWN TO BELOW THE CASCADE PASSES BY EARLY FRIDAY MORNING AS
THE COLD UPPER TROUGH SLIDES OVER THE REGION. HOWEVER...THE BULK OF
THE PRECIPITATION WILL HAVE FINISHED BY THE TIME SNOW LEVELS COME
DOWN. OVERALL...A FEW INCHES OF SNOW AT THE PASSES ARE POSSIBLE WITH
A FEW ADDITIONAL INCHES OF SNOW AT THE HIGHER CASCADE ELEVATIONS.
ADDED A SLIGHT CHANCE OF THUNDERSTORMS TO THE FORECAST FOR THE COAST
RANGE AND POINTS WEST FOR EARLY TOMORROW MORNING. THE UPPER TROUGH
MOVES THROUGH THE AREA AND MODEL FORECAST SOUNDINGS INDICATE DECENT
INSTABILITY.

MODELS CONTINUE TO REMAIN IN GOOD AGREEMENT THAT A VERY MOIST
ATMOSPHERIC RIVER PATTERN WILL SET UP DIRECTING LARGE AMOUNTS OF
MOSITURE AT SW WASHINGTON AND NW OREGON THIS WEEKEND. HEAVY RAINFALL
LIKELY BEGINS BY EARLY SATURDAY MORNING AND CONTINUES THROUGH AT
LEAST SUNDAY. THE COAST RANGE...WILLAPA HILLS...CASCADES...AND
FOOTHILLS WILL LIKELY SEE ON THE ORDER OF 8 TO 12 INCHES OF RAINFALL.
LOCATIONS ON THE COAST MAY SEE 5 TO 7 INCHES OF RAIN...WHILE THE
INTERIOR VALLEY LOCATIONS CAN EXPECT 3 TO 4 INCHES. WHILE SOME
UNCERTAINTY IN THE PRECISE AREAS OF MAXIMUM RAINFALL
EXISTS...CONFIDENCE IS INCREASING THAT LARGE AMOUNTS OF PRECIPITATION
WILL OCCUR ACROSS THE FORECAST AREA WITH THIS SYSTEM. AS A
RESULT...THERE IS THE POTENTIAL FOR SHARP RISES ON AREA RIVERS AND
STREAMS THAT MAY RESULT IN FLOODING. SEE THE HYDROLOGY SECTION FOR
MORE DETAILS.

IN ADDITION...THOSE PLANNING TO BE ALONG THE COAST AT AREAS BEACHES
SHOULD CLOSELY MONITOR THE CONDITIONS FOR THIS WEEKEND. RAPIDLY
BUILDING SEAS WILL BRING THE POTENTIAL FOR DANGEROUS HIGH SURF ALONG
THE AREA BEACHES ON FRIDAY. LONG PERIOD SWELLS MAY REACH SHORE AND
SURPRISE INDIVIDUALS WHO ARE UNAWARE. ANYONE ON THE BEACHES SHOULD
EXERCISE EXTREME CAUTION AND AVOID THE SURF ZONE AS LARGE WAVES MAY
WASH OVER BEACHES AND JETTIES WITH LITTLE WARNING. SOME POTENTIAL FOR
MINOR TIDAL OVERFLOW IS POSSIBLE FOR SATURDAY AND SUNDAY...ESPECIALLY
AROUND HIGH TIDES. THIS THREAT COULD BE ENHANCED BY HIGH FLOWS ON
RIVERS IN RESPONSE TO THE RAINFALL THIS WEEKEND.  CULLEN

&&

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS. SUNDAY NIGHT
THROUGH THURSDAY...MODELS AGREE THE WEEKEND RAIN/FLOODING EVENT WILL
WIND DOWN SUNDAY NIGHT INTO MONDAY. A MUCH WEAKER FRONT MAY SLIDE
SOUTHWARD ACROSS NORTHWEST OREGON AND SOUTHWEST WASHINGTON MONDAY
NIGHT INTO TUESDAY. MODELS HAVE WAVERED A BIT ON THIS SYSTEM SO POPS
WERE GENERALLY KEPT IN THE HIGH END CHANCE TO LOW END LIKELY.
CONDITIONS SHOULD TEMPORARILY DRY OUT LATE TUESDAY BEFORE A COLDER
STORM SYSTEM BRINGS SHOWERS TO THE AREA ON WEDNESDAY...BUT
DISCREPANCIES CONTINUE AMONG THE MODELS. SNOW LEVELS WILL LIKELY
LOWER WELL BELOW PASS LEVEL SO HOLIDAY TRAVELERS HEADED OVER THE
CASCADE PASSES WILL CERTAINLY NEED TO MONITOR THE FORECAST. COLD
NORTHERLY WILL FOLLOW AND ALLOW TEMPERATURES TO COOL WELL BELOW
NORMAL AS CONDITIONS DRY OUT LATE WEEK. EASTERLY WINDS WILL LIKELY
RETURN. /NEUMAN

&&

.HYDROLOGY...SITUATION SETTING UP FOR A MEMORABLE HYDROLOGIC EVENT
MAINLY FOR LATER THIS WEEKEND AND HEADING INTO NEXT WEEK. STRONG AND
DEEP MOIST WESTERLY FLOW WILL BEGIN CROSSING THE PACNW COAST COME
SATURDAY MORNING. A VERY LONG FETCH OF MOISTURE IS STRETCHING ACROSS
THE PACIFIC WITH ORIGINS WEST TO THE SOUTH CHINA SEA. THIS MOIST AIR
MASS WILL BE PUSHED EAST BY A 150 TO 170 KT JET AND WESTERLY 25 TO
50 KT LOWER LEVEL WINDS. AS SUCH...THIS CONTINUES TO GIVE THE
APPEARANCE OF A CLASSIC HIGH PRECIPITATION ATMOSPHERIC RIVER EVENT
WHERE THE DEEP MOIST FLOW WILL SPEND A SIGNIFICANT AMOUNT OF TIME
ON A NEARLY PERPENDICULAR COURSE AGAINST THE COAST RANGE WITH THE
CASCADES TAKING A BIT HIGHER OF THE IMPACT. AS OF THE MORNING MODEL
RUNS AND RECENT NWRFC UPDATES...IT APPEARS MULTIPLE COAST RANGE
RIVERS HAVE A MODERATE POTENTIAL OF EXCEEDING FLOOD STAGE.
ADDITIONALLY...THIS EVENT HAS SUFFICIENT DEPTH TO BRING SIGNIFICANT
RAINS TO THE NORTH OREGON AND SOUTH WASHINGTON CASCADES WHERE RIVERS
WILL ALSO SEE POTENTIAL FOR NOTABLE FLOODING. WILL CONTINUE THE
HYDROLOGIC OUTLOOK (PDXESFPQR) PRODUCT HIGHLIGHTING CONCERNS. KEEP
IN MIND THAT DETAILS WILL ALWAYS BE IN FLUX UNDER THESE SCENARIOS AS
SUBTLE NORTH/SOUTH SHIFTS COLD MAKE DRAMATIC DIFFERENCES IN WHICH
BASINS RECEIVE EXTENDED PERIODS OF MODERATE TO HEAVY RAIN. PLEASE
CONTINUE TO FOLLOW THE LATEST FORECASTS AND IMPACTS AS CONDITIONS
WARRANT. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE)

/JBONK

&&

.AVIATION...MOSTLY LOW TO MID RANGE VFR ACROSS REGION...BUT DO
HAVE AREAS OF MVFR CIGS WITH RAIN OVER COAST RANGE AND ALONG
COAST THIS EVENING. THIS WILL PUSH INLAND THROUGH 08Z. FRONT NOW
JUST ONSHORE...AND WILL PUSH THE CASCADES BY 08Z. CONDITIONS
SLOWLY IMPROVE TO VFR WITH TRANSITION TO SHOWERS BEHIND THE FRONT.
WILL KEEP SLIGHT CHANCE OF TS ALONG THE COAST FOR LATER TONIGHT
AND INTO FRI AM. OTHERWISE...MOSTLY VFR ON FRI WITH POCKETS OF
MVFR CONDITIONS UNDER SHOWERS.

PDX AND APPROACHES...VFR THIS EVENING AND FRI. BUT WILL HAVE
PERIOD OF MVFR CIGS DOWN TO 2500 FT AS FRONT MOVES ACROSS REGION.
BEST TIMING SEEMS TO BE 07Z TO 12Z FOR SUCH CONDITIONS. OTHERWISE
NO SIGNIFICANT IMPACTS EXPECTED FOR OPS AREA.         ROCKEY.
&&

.MARINE...WITH FRONT JUST ONSHORE...WINDS HAVE NOW EASED.
GENERALLY GUSTING TO NEAR 25 KT. SO WILL REPLACE GALE WARNING WITH
SMALL CRAFT ADVISORIES FOR BOTH WINDS AND SEAS. BOTH ADVISORIES
WILL EXTEND THROUGH FRI NIGHT.

SEAS HOLDING AT 12 TO 14 FT TONIGHT BUT WILL DROP BACK A FEW FEET
FOR FRI. BUT WITH INCREASING WINDS LATER FRI NIGHT...SO SEAS WILL
BUILD. STILL LOOK LIKE BUILDING UP TO NEAR 20 FT BY LATE FRI
AFTERNOON...AND LIKELY AROUND 25 FT FRI NIGHT. WINDS AND SEAS WILL
EASE BACK LATER SAT NIGHT AND SUN.                    ROCKEY.
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH SURF ADVISORY FROM 10 AM FRIDAY TO 4 AM PST SATURDAY FOR
     CENTRAL OREGON COAST-NORTH OREGON COAST.

WA...HIGH SURF ADVISORY FROM 10 AM FRIDAY TO 4 AM PST SATURDAY FOR
     SOUTH WASHINGTON COAST.

PZ...SMALL CRAFT ADVISORY FOR BOTH WINDS AND HAZARDOUS SEAS FOR
         TONIGHT THROUGH FRI NIGHT.
     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS
         THROUGH FRI NIGHT.

&&


$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.





000
FXUS66 KPQR 182351
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
350 PM PST THU DEC 18 2014

.SYNOPSIS...RAIN WILL INCREASE TONIGHT AS A MORE ORGANIZED FRONTAL
SYSTEM PUSHES ONSHORE. A COLDER UPPER TROUGH MOVES ACROSS THE AREA
FRIDAY...WHICH WILL LOWER SNOW LEVELS BELOW THE CASCADE PASSES. MILD
AND VERY WET WEATHER IS EXPECTED THIS WEEKEND WITH AN ATMOSPHERIC
RIVER BRINGING HEAVY RAIN TO THE REGION. THE EXACT LOCATION OF THE
JET STREAM AND ASSOCIATED MOISTURE PLUME IS STILL IN QUESTION...BUT
THERE IS INCREASING CONFIDENCE THAT IT WILL TAKE AIM AT SW WASHINGTON
AND NW OREGON. THERE IS THE POTENTIAL FOR SOME FLOODING LATE THIS
WEEKEND INTO EARLY NEXT WEEK.

&&

.SHORT TERM....TONIGHT THROUGH SUNDAY...NWS DOPPLER RADAR CONTINUES
TO DEPICT LIGHT RAIN SPREADING ACROSS THE REGION THIS AFTERNOON IN
ASSOCIATION WITH AN APPROACHING FRONTAL SYSTEM. RAINFALL TOTALS THIS
AFTERNOON HAVE BEEN LIGHT...WITH TOTALS GENERALLY AROUND ONE TENTH OF
AN INCH FOR MOST SPOTS. SOME OF THE HIGHER ELEVATION LOCATIONS HAVE
MEASURED AROUND ONE QUARTER INCH. MODELS REMAIN IN AGREEMENT THAT THE
FRONTAL BOUNDARY WILL PUSH ONSHORE THIS EVENING. AHEAD OF THE
FRONT...GUSTY SOUTH WINDS WILL INCREASE ACROSS THE COASTAL
AREAS...WITH GUSTS INTO THE 50-55 MPH RANGE THIS EVENING FOR THE MORE
EXPOSED BEACHES AND HEADLANDS.

THE SYSTEM TONIGHT WILL BRING A SHOT OF RAIN TONIGHT THROUGH EARLY
FRIDAY WITH AROUND AN INCH OF RAIN FOR THE COAST AND COAST
RANGE AND AROUND A HALF INCH FOR THE VALLEY. SNOW LEVELS WILL
GRADUALLY RISE A LITTLE THIS EVENING AHEAD OF THE FRONT...BUT LOWER
DOWN TO BELOW THE CASCADE PASSES BY EARLY FRIDAY MORNING AS THE COLD
UPPER TROUGH SLIDES OVER THE REGION. HOWEVER...THE BULK OF THE
PRECIPITATION WILL HAVE FINISHED BY THE TIME SNOW LEVELS COME DOWN.
OVERALL...A FEW INCHES OF SNOW AT THE PASSES ARE POSSIBLE WITH A FEW
ADDITIONAL INCHES OF SNOW AT THE HIGHER CASCADE ELEVATIONS. ADDED A
SLIGHT CHANCE OF THUNDERSTORMS TO THE FORECAST FOR THE COAST RANGE
AND POINTS WEST FOR EARLY TOMORROW MORNING. THE UPPER TROUGH MOVES
THROUGH THE AREA AND MODEL FORECAST SOUNDINGS INDICATE DECENT
INSTABILITY.

MODELS CONTINUE TO REMAIN IN GOOD AGREEMENT THAT A VERY MOIST
ATMOSPHERIC RIVER PATTERN WILL SET UP DIRECTING LARGE AMOUNTS OF
MOSITURE AT SW WASHINGTON AND NW OREGON THIS WEEKEND. HEAVY RAINFALL
LIKELY BEGINS BY EARLY SATURDAY MORNING AND CONTINUES THROUGH AT
LEAST SUNDAY. THE COAST RANGE...WILLAPA HILLS...CASCADES...AND
FOOTHILLS WILL LIKELY SEE ON THE ORDER OF 8 TO 12 INCHES OF RAINFALL.
LOCATIONS ON THE COAST MAY SEE 5 TO 7 INCHES OF RAIN...WHILE THE
INTERIOR VALLEY LOCATIONS CAN EXPECT 3 TO 4 INCHES. WHILE SOME
UNCERTAINTY IN THE PRECISE AREAS OF MAXIMUM RAINFALL
EXISTS...CONFIDENCE IS INCREASING THAT LARGE AMOUNTS OF PRECIPITATION
WILL OCCUR ACROSS THE FORECAST AREA WITH THIS SYSTEM. AS A
RESULT...THERE IS THE POTENTIAL FOR SHARP RISES ON AREA RIVERS AND
STREAMS THAT MAY RESULT IN FLOODING. SEE THE HYDROLOGY SECTION FOR
MORE DETAILS.

IN ADDITION...THOSE PLANNING TO BE ALONG THE COAST AT AREAS BEACHES
SHOULD CLOSELY MONITOR THE CONDITIONS FOR THIS WEEKEND. RAPIDLY
BUILDING SEAS WILL BRING THE POTENTIAL FOR DANGEROUS HIGH SURF ALONG
THE AREA BEACHES ON FRIDAY. LONG PERIOD SWELLS MAY REACH SHORE AND
SURPRISE INDIVIDUALS WHO ARE UNAWARE. ANYONE ON THE BEACHES SHOULD
EXERCISE EXTREME CAUTION AND AVOID THE SURF ZONE AS LARGE WAVES MAY
WASH OVER BEACHES AND JETTIES WITH LITTLE WARNING. SOME POTENTIAL FOR
MINOR TIDAL OVERFLOW IS POSSIBLE FOR SATURDAY AND SUNDAY...ESPECIALLY
AROUND HIGH TIDES. THIS THREAT COULD BE ENHANCED BY HIGH FLOWS ON
RIVERS IN RESPONSE TO THE RAINFALL THIS WEEKEND.  CULLEN

&&

.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...MODELS AGREE THE
WEEKEND RAIN/FLOODING EVENT WILL WIND DOWN SUNDAY NIGHT INTO MONDAY.
A MUCH WEAKER FRONT MAY SLIDE SOUTHWARD ACROSS NORTHWEST OREGON AND
SOUTHWEST WASHINGTON MONDAY NIGHT INTO TUESDAY. MODELS HAVE WAVERED
A BIT ON THIS SYSTEM SO POPS WERE GENERALLY KEPT IN THE HIGH END
CHANCE TO LOW END LIKELY. CONDITIONS SHOULD TEMPORARILY DRY OUT LATE
TUESDAY BEFORE A COLDER STORM SYSTEM BRINGS SHOWERS TO THE AREA ON
WEDNESDAY...BUT DISCREPANCIES CONTINUE AMONG THE MODELS. SNOW LEVELS
WILL LIKELY LOWER WELL BELOW PASS LEVEL SO HOLIDAY TRAVELERS HEADED
OVER THE CASCADE PASSES WILL CERTAINLY NEED TO MONITOR THE FORECAST.
COLD NORTHERLY WILL FOLLOW AND ALLOW TEMPERATURES TO COOL WELL BELOW
NORMAL AS CONDITIONS DRY OUT LATE WEEK. EASTERLY WINDS WILL LIKELY
RETURN. /NEUMAN

&&

.HYDROLOGY...SITUATION SETTING UP FOR A MEMORABLE HYDROLOGIC EVENT
MAINLY FOR LATER THIS WEEKEND AND HEADING INTO NEXT WEEK. STRONG AND
DEEP MOIST WESTERLY FLOW WILL BEGIN CROSSING THE PACNW COAST COME
SATURDAY MORNING. A VERY LONG FETCH OF MOISTURE IS STRETCHING ACROSS
THE PACIFIC WITH ORIGINS WEST TO THE SOUTH CHINA SEA. THIS MOIST AIR
MASS WILL BE PUSHED EAST BY A 150 TO 170 KT JET AND WESTERLY 25 TO
50 KT LOWER LEVEL WINDS. AS SUCH...THIS CONTINUES TO GIVE THE
APPEARANCE OF A CLASSIC HIGH PRECIPITATION ATMOSPHERIC RIVER EVENT
WHERE THE DEEP MOIST FLOW WILL SPEND A SIGNIFICANT AMOUNT OF TIME
ON A NEARLY PERPENDICULAR COURSE AGAINST THE COAST RANGE WITH THE
CASCADES TAKING A BIT HIGHER OF THE IMPACT. AS OF THE MORNING MODEL
RUNS AND RECENT NWRFC UPDATES...IT APPEARS MULTIPLE COAST RANGE
RIVERS HAVE A MODERATE POTENTIAL OF EXCEEDING FLOOD STAGE.
ADDITIONALLY...THIS EVENT HAS SUFFICIENT DEPTH TO BRING SIGNIFICANT
RAINS TO THE NORTH OREGON AND SOUTH WASHINGTON CASCADES WHERE RIVERS
WILL ALSO SEE POTENTIAL FOR NOTABLE FLOODING. WILL CONTINUE THE
HYDROLOGIC OUTLOOK (PDXESFPQR) PRODUCT HIGHLIGHTING CONCERNS. KEEP
IN MIND THAT DETAILS WILL ALWAYS BE IN FLUX UNDER THESE SCENARIOS AS
SUBTLE NORTH/SOUTH SHIFTS COLD MAKE DRAMATIC DIFFERENCES IN WHICH
BASINS RECEIVE EXTENDED PERIODS OF MODERATE TO HEAVY RAIN. PLEASE
CONTINUE TO FOLLOW THE LATEST FORECASTS AND IMPACTS AS CONDITIONS
WARRANT. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE)

/JBONK

&&

.AVIATION...MIX OF VFR AND MVFR CIGS AND VIS THIS EVENING WILL
DROP TO MVFR/IFR AFTER MIDNIGHT. POST FRONTAL SHOWERS ACROSS THE
AREA WILL BRING DOWN CIGS AND VIS. WINDS AT KTTD GUSTING TO 30 KTS
WILL HELP KEEP CIGS UP AT KTTD AND POSSIBLY KPDX...THOUGH CIGS MAY
DROP TO MVFR/IFR WITH HEAVIER SHOWERS. RAIN TO CONTINUE THROUGH
THE DAY FRIDAY...WITH A CHANCE OF THUNDERSTORMS ALONG THE COAST
FRIDAY MORNING. CIGS AND VIS LIKELY TO IMPROVE TO A MIX OF VFR AND
MVFR BY FRIDAY AFTERNOON.

PDX AND APPROACHES...VFR CIGS LIKELY TO STAY VFR THIS
EVENING...WITH PERIODS OF MVFR CIGS AND VIS STARTING LATE THIS
EVENING BEHIND THE COLD FRONT. CIGS AND VIS LIKELY TO DROP TO
MVFR/IFR EARLY FRIDAY MORNING...BUT IMPROVE TO VFR BY FRIDAY
AFTERNOON. -MCCOY

&&

.MARINE...COMBINED SEAS AROUND 12 FT BUILDING TO 14 TO 16 FT BY
FRIDAY MORNING. SEAS WILL RAPIDLY BUILD DURING THE AFTERNOON HOURS AS
THE 20 TO 22 FT SWELL APPROACHES...BRINGING SEAS UP TO 22 FT BY
FRIDAY EVENING. SEAS WILL REMAIN AROUND 20 TO 22 FT THROUGH
SATURDAY MORNING. AS THE SWELL BEGINS TO DROP OFF...SOUTHERLY
WINDS INCREASE AHEAD OF OUR NEXT STRONG COLD FRONT. GALES LOOK
LIKELY WITH THIS SYSTEM...KEEPING SEAS AROUND 20 TO 22 FT THROUGH
SATURDAY MORNING. SEAS BEGIN TO DROP BELOW 20 FT SATURDAY
AFTERNOON BEHIND THE FRONT...AS WINDS EASE...BUT SEAS WILL STAY IN
THE UPPER TEENS THROUGH SUNDAY EVENING.

ANOTHER WEAK FRONTAL SYSTEM COULD KEEP SMALL CRAFT WINDS ACROSS
OUR SOUTHERN WATERS THROUGH SUNDAY NIGHT. OTHERWISE...RELATIVELY
BENIGN WEATHER EXPECTED EARLY NEXT WEEK AS HIGH PRESSURE BUILDS
OVER THE WATERS. -MCCOY

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH SURF ADVISORY FROM 10 AM FRIDAY TO 4 AM PST SATURDAY FOR
     CENTRAL OREGON COAST-NORTH OREGON COAST.

WA...HIGH SURF ADVISORY FROM 10 AM FRIDAY TO 4 AM PST SATURDAY FOR
     SOUTH WASHINGTON COAST.

PZ...GALE WARNING UNTIL MIDNIGHT PST TONIGHT FOR COASTAL WATERS FROM
     CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 3 PM PST
     SUNDAY.

&&


$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.





000
FXUS66 KPQR 182351
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
350 PM PST THU DEC 18 2014

.SYNOPSIS...RAIN WILL INCREASE TONIGHT AS A MORE ORGANIZED FRONTAL
SYSTEM PUSHES ONSHORE. A COLDER UPPER TROUGH MOVES ACROSS THE AREA
FRIDAY...WHICH WILL LOWER SNOW LEVELS BELOW THE CASCADE PASSES. MILD
AND VERY WET WEATHER IS EXPECTED THIS WEEKEND WITH AN ATMOSPHERIC
RIVER BRINGING HEAVY RAIN TO THE REGION. THE EXACT LOCATION OF THE
JET STREAM AND ASSOCIATED MOISTURE PLUME IS STILL IN QUESTION...BUT
THERE IS INCREASING CONFIDENCE THAT IT WILL TAKE AIM AT SW WASHINGTON
AND NW OREGON. THERE IS THE POTENTIAL FOR SOME FLOODING LATE THIS
WEEKEND INTO EARLY NEXT WEEK.

&&

.SHORT TERM....TONIGHT THROUGH SUNDAY...NWS DOPPLER RADAR CONTINUES
TO DEPICT LIGHT RAIN SPREADING ACROSS THE REGION THIS AFTERNOON IN
ASSOCIATION WITH AN APPROACHING FRONTAL SYSTEM. RAINFALL TOTALS THIS
AFTERNOON HAVE BEEN LIGHT...WITH TOTALS GENERALLY AROUND ONE TENTH OF
AN INCH FOR MOST SPOTS. SOME OF THE HIGHER ELEVATION LOCATIONS HAVE
MEASURED AROUND ONE QUARTER INCH. MODELS REMAIN IN AGREEMENT THAT THE
FRONTAL BOUNDARY WILL PUSH ONSHORE THIS EVENING. AHEAD OF THE
FRONT...GUSTY SOUTH WINDS WILL INCREASE ACROSS THE COASTAL
AREAS...WITH GUSTS INTO THE 50-55 MPH RANGE THIS EVENING FOR THE MORE
EXPOSED BEACHES AND HEADLANDS.

THE SYSTEM TONIGHT WILL BRING A SHOT OF RAIN TONIGHT THROUGH EARLY
FRIDAY WITH AROUND AN INCH OF RAIN FOR THE COAST AND COAST
RANGE AND AROUND A HALF INCH FOR THE VALLEY. SNOW LEVELS WILL
GRADUALLY RISE A LITTLE THIS EVENING AHEAD OF THE FRONT...BUT LOWER
DOWN TO BELOW THE CASCADE PASSES BY EARLY FRIDAY MORNING AS THE COLD
UPPER TROUGH SLIDES OVER THE REGION. HOWEVER...THE BULK OF THE
PRECIPITATION WILL HAVE FINISHED BY THE TIME SNOW LEVELS COME DOWN.
OVERALL...A FEW INCHES OF SNOW AT THE PASSES ARE POSSIBLE WITH A FEW
ADDITIONAL INCHES OF SNOW AT THE HIGHER CASCADE ELEVATIONS. ADDED A
SLIGHT CHANCE OF THUNDERSTORMS TO THE FORECAST FOR THE COAST RANGE
AND POINTS WEST FOR EARLY TOMORROW MORNING. THE UPPER TROUGH MOVES
THROUGH THE AREA AND MODEL FORECAST SOUNDINGS INDICATE DECENT
INSTABILITY.

MODELS CONTINUE TO REMAIN IN GOOD AGREEMENT THAT A VERY MOIST
ATMOSPHERIC RIVER PATTERN WILL SET UP DIRECTING LARGE AMOUNTS OF
MOSITURE AT SW WASHINGTON AND NW OREGON THIS WEEKEND. HEAVY RAINFALL
LIKELY BEGINS BY EARLY SATURDAY MORNING AND CONTINUES THROUGH AT
LEAST SUNDAY. THE COAST RANGE...WILLAPA HILLS...CASCADES...AND
FOOTHILLS WILL LIKELY SEE ON THE ORDER OF 8 TO 12 INCHES OF RAINFALL.
LOCATIONS ON THE COAST MAY SEE 5 TO 7 INCHES OF RAIN...WHILE THE
INTERIOR VALLEY LOCATIONS CAN EXPECT 3 TO 4 INCHES. WHILE SOME
UNCERTAINTY IN THE PRECISE AREAS OF MAXIMUM RAINFALL
EXISTS...CONFIDENCE IS INCREASING THAT LARGE AMOUNTS OF PRECIPITATION
WILL OCCUR ACROSS THE FORECAST AREA WITH THIS SYSTEM. AS A
RESULT...THERE IS THE POTENTIAL FOR SHARP RISES ON AREA RIVERS AND
STREAMS THAT MAY RESULT IN FLOODING. SEE THE HYDROLOGY SECTION FOR
MORE DETAILS.

IN ADDITION...THOSE PLANNING TO BE ALONG THE COAST AT AREAS BEACHES
SHOULD CLOSELY MONITOR THE CONDITIONS FOR THIS WEEKEND. RAPIDLY
BUILDING SEAS WILL BRING THE POTENTIAL FOR DANGEROUS HIGH SURF ALONG
THE AREA BEACHES ON FRIDAY. LONG PERIOD SWELLS MAY REACH SHORE AND
SURPRISE INDIVIDUALS WHO ARE UNAWARE. ANYONE ON THE BEACHES SHOULD
EXERCISE EXTREME CAUTION AND AVOID THE SURF ZONE AS LARGE WAVES MAY
WASH OVER BEACHES AND JETTIES WITH LITTLE WARNING. SOME POTENTIAL FOR
MINOR TIDAL OVERFLOW IS POSSIBLE FOR SATURDAY AND SUNDAY...ESPECIALLY
AROUND HIGH TIDES. THIS THREAT COULD BE ENHANCED BY HIGH FLOWS ON
RIVERS IN RESPONSE TO THE RAINFALL THIS WEEKEND.  CULLEN

&&

.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...MODELS AGREE THE
WEEKEND RAIN/FLOODING EVENT WILL WIND DOWN SUNDAY NIGHT INTO MONDAY.
A MUCH WEAKER FRONT MAY SLIDE SOUTHWARD ACROSS NORTHWEST OREGON AND
SOUTHWEST WASHINGTON MONDAY NIGHT INTO TUESDAY. MODELS HAVE WAVERED
A BIT ON THIS SYSTEM SO POPS WERE GENERALLY KEPT IN THE HIGH END
CHANCE TO LOW END LIKELY. CONDITIONS SHOULD TEMPORARILY DRY OUT LATE
TUESDAY BEFORE A COLDER STORM SYSTEM BRINGS SHOWERS TO THE AREA ON
WEDNESDAY...BUT DISCREPANCIES CONTINUE AMONG THE MODELS. SNOW LEVELS
WILL LIKELY LOWER WELL BELOW PASS LEVEL SO HOLIDAY TRAVELERS HEADED
OVER THE CASCADE PASSES WILL CERTAINLY NEED TO MONITOR THE FORECAST.
COLD NORTHERLY WILL FOLLOW AND ALLOW TEMPERATURES TO COOL WELL BELOW
NORMAL AS CONDITIONS DRY OUT LATE WEEK. EASTERLY WINDS WILL LIKELY
RETURN. /NEUMAN

&&

.HYDROLOGY...SITUATION SETTING UP FOR A MEMORABLE HYDROLOGIC EVENT
MAINLY FOR LATER THIS WEEKEND AND HEADING INTO NEXT WEEK. STRONG AND
DEEP MOIST WESTERLY FLOW WILL BEGIN CROSSING THE PACNW COAST COME
SATURDAY MORNING. A VERY LONG FETCH OF MOISTURE IS STRETCHING ACROSS
THE PACIFIC WITH ORIGINS WEST TO THE SOUTH CHINA SEA. THIS MOIST AIR
MASS WILL BE PUSHED EAST BY A 150 TO 170 KT JET AND WESTERLY 25 TO
50 KT LOWER LEVEL WINDS. AS SUCH...THIS CONTINUES TO GIVE THE
APPEARANCE OF A CLASSIC HIGH PRECIPITATION ATMOSPHERIC RIVER EVENT
WHERE THE DEEP MOIST FLOW WILL SPEND A SIGNIFICANT AMOUNT OF TIME
ON A NEARLY PERPENDICULAR COURSE AGAINST THE COAST RANGE WITH THE
CASCADES TAKING A BIT HIGHER OF THE IMPACT. AS OF THE MORNING MODEL
RUNS AND RECENT NWRFC UPDATES...IT APPEARS MULTIPLE COAST RANGE
RIVERS HAVE A MODERATE POTENTIAL OF EXCEEDING FLOOD STAGE.
ADDITIONALLY...THIS EVENT HAS SUFFICIENT DEPTH TO BRING SIGNIFICANT
RAINS TO THE NORTH OREGON AND SOUTH WASHINGTON CASCADES WHERE RIVERS
WILL ALSO SEE POTENTIAL FOR NOTABLE FLOODING. WILL CONTINUE THE
HYDROLOGIC OUTLOOK (PDXESFPQR) PRODUCT HIGHLIGHTING CONCERNS. KEEP
IN MIND THAT DETAILS WILL ALWAYS BE IN FLUX UNDER THESE SCENARIOS AS
SUBTLE NORTH/SOUTH SHIFTS COLD MAKE DRAMATIC DIFFERENCES IN WHICH
BASINS RECEIVE EXTENDED PERIODS OF MODERATE TO HEAVY RAIN. PLEASE
CONTINUE TO FOLLOW THE LATEST FORECASTS AND IMPACTS AS CONDITIONS
WARRANT. RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE)

/JBONK

&&

.AVIATION...MIX OF VFR AND MVFR CIGS AND VIS THIS EVENING WILL
DROP TO MVFR/IFR AFTER MIDNIGHT. POST FRONTAL SHOWERS ACROSS THE
AREA WILL BRING DOWN CIGS AND VIS. WINDS AT KTTD GUSTING TO 30 KTS
WILL HELP KEEP CIGS UP AT KTTD AND POSSIBLY KPDX...THOUGH CIGS MAY
DROP TO MVFR/IFR WITH HEAVIER SHOWERS. RAIN TO CONTINUE THROUGH
THE DAY FRIDAY...WITH A CHANCE OF THUNDERSTORMS ALONG THE COAST
FRIDAY MORNING. CIGS AND VIS LIKELY TO IMPROVE TO A MIX OF VFR AND
MVFR BY FRIDAY AFTERNOON.

PDX AND APPROACHES...VFR CIGS LIKELY TO STAY VFR THIS
EVENING...WITH PERIODS OF MVFR CIGS AND VIS STARTING LATE THIS
EVENING BEHIND THE COLD FRONT. CIGS AND VIS LIKELY TO DROP TO
MVFR/IFR EARLY FRIDAY MORNING...BUT IMPROVE TO VFR BY FRIDAY
AFTERNOON. -MCCOY

&&

.MARINE...COMBINED SEAS AROUND 12 FT BUILDING TO 14 TO 16 FT BY
FRIDAY MORNING. SEAS WILL RAPIDLY BUILD DURING THE AFTERNOON HOURS AS
THE 20 TO 22 FT SWELL APPROACHES...BRINGING SEAS UP TO 22 FT BY
FRIDAY EVENING. SEAS WILL REMAIN AROUND 20 TO 22 FT THROUGH
SATURDAY MORNING. AS THE SWELL BEGINS TO DROP OFF...SOUTHERLY
WINDS INCREASE AHEAD OF OUR NEXT STRONG COLD FRONT. GALES LOOK
LIKELY WITH THIS SYSTEM...KEEPING SEAS AROUND 20 TO 22 FT THROUGH
SATURDAY MORNING. SEAS BEGIN TO DROP BELOW 20 FT SATURDAY
AFTERNOON BEHIND THE FRONT...AS WINDS EASE...BUT SEAS WILL STAY IN
THE UPPER TEENS THROUGH SUNDAY EVENING.

ANOTHER WEAK FRONTAL SYSTEM COULD KEEP SMALL CRAFT WINDS ACROSS
OUR SOUTHERN WATERS THROUGH SUNDAY NIGHT. OTHERWISE...RELATIVELY
BENIGN WEATHER EXPECTED EARLY NEXT WEEK AS HIGH PRESSURE BUILDS
OVER THE WATERS. -MCCOY

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH SURF ADVISORY FROM 10 AM FRIDAY TO 4 AM PST SATURDAY FOR
     CENTRAL OREGON COAST-NORTH OREGON COAST.

WA...HIGH SURF ADVISORY FROM 10 AM FRIDAY TO 4 AM PST SATURDAY FOR
     SOUTH WASHINGTON COAST.

PZ...GALE WARNING UNTIL MIDNIGHT PST TONIGHT FOR COASTAL WATERS FROM
     CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 3 PM PST
     SUNDAY.

&&


$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 181816
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1016 AM PST THU DEC 18 2014

.SYNOPSIS...RAIN WILL INCREASE TONIGHT AS A MORE ORGANIZED FRONTAL
SYSTEM PUSHES ONSHORE. A COLDER UPPER TROUGH MOVES ACROSS THE AREA
FRIDAY...WHICH WILL LOWER SNOW LEVELS BELOW THE CASCADE PASSES. MILD
AND VERY WET WEATHER IS EXPECTED THIS WEEKEND. THERE IS POTENTIAL FOR
AN ATMOSPHERIC RIVER AND ASSOCIATED HEAVY RAIN TO DEVELOP OVER THE
AREA. THE EXACT LOCATION OF THE JET STREAM AND ASSOCIATED MOISTURE
PLUME ARE STILL IN DOUBT. THERE IS THE POTENTIAL FOR SOME FLOODING
LATE THIS WEEKEND INTO EARLY NEXT WEEK.

&&

.UPDATE...SOME LIGHT RAIN CONTINUES TO SPREAD ACROSS SOUTHWEST
WASHINGTON AND NORTHWEST OREGON THIS MORNING AHEAD OF AN APPROACHING
FRONTAL SYSTEM. MODELS INDICATE THAT THIS RAIN WILL CONTINUE THROUGH
THE DAY WITH INCREASING COVERAGE...PARTICULARLY ALONG THE COAST AND
ACROSS THE NORTHERN PORTIONS OF THE FORECAST AREA. THEREFORE
INCREASED POPS FOR THESE LOCATIONS WITH THE MORNING UPDATE. EXPECT
THESE RAINFALL ACCUMULATIONS TO REMAIN FAIRLY LIGHT FOR MOST
LOCATIONS DURING THE DAY...THOUGH HEAVIER RAIN WILL MOVE ONSHORE WITH
THE COLD FRONT THIS EVENING. OTHERWISE...FEW CHANGES TO THE FORECAST.
12Z MODELS REMAIN CONSISTENT WITH SIGNIFICANT RAINFALL FOR THE
WEEKEND WITH A DEVELOPING ATMOSPHERIC RIVER EVENT.  CULLEN

&&

.PREV DISC... /ISSUED 414 AM PST THU DEC 18 2014/

SHORT TERM...THURSDAY THROUGH SATURDAY...WATER VAPOR IMAGERY AS OF
1030Z SHOWS A DEEP UPPER LOW IN THE GULF OF ALASKA WITH A FRONTAL
SYSTEM TAKING SHAPE NEAR 135W. THE 06Z NAM12 RUN SHOWS A WEAK SURFACE
LOW OFF THE S OREGON COAST AT 09Z. THIS FEATURE IS VERY DIFFICULT TO
PICK OUT IN THE WATER VAPOR LOOPER. THE NAM SHOWS THIS LOW FILLING
OVERNIGHT AS IT DRIFTS TO THE NE. NWS PORTLAND DUAL-POL DOPPLER RADAR
SHOWING DECREASING RADAR RETURNS...WITH THE STRONGEST ECHOES IN THE
WILLAPA HILLS AND S WA CASCADES.

NAM...GFS AND ECMWF ALL INDICATE A WEAK 500 MB RIDGE TO MOVE ACROSS
THE AREA TODAY. HOWEVER...MODEL CROSS-SECTIONS AND TIME-HEIGHT
FORECASTS MAINTAIN MOIST LOW-LEVELS THROUGH THE DAY. THUS...STILL
EXPECT LIGHT QPF ACROSS THE FORECAST AREA TODAY...AHEAD OF THE NEXT
FRONTAL SYSTEM. MODELS APPEAR TO BE IN REASONABLE AGREEMENT WITH THIS
FRONT...WITH LANDFALL SOMETIME AROUND 00Z FRI OR SHORTLY THEREAFTER.
ONE CONCERN WAS THE POTENTIAL FOR HIGH WIND ALONG THE COASTAL
HEADLANDS. PREVIOUS SHIFT HAD ISSUED A HIGH WIND WATCH FOR LATE THIS
AFTERNOON THROUGH 08Z FRI. UPON FURTHER REVIEW...NOT SEEING ENOUGH IN
THE 850 MB TO 950 MB WIND FIELDS TO UPGRADE TO A WARNING. THE 00Z
WRF-GFS VALID 00Z FRI HAS A COASTAL JET SIGNATURE OVER THE OREGON
COASTAL WATERS...WITH FORECAST 10M WIND GUSTS OF 55 KT. HOWEVER...BY
03Z FRI THE MODEL HAS JUST A SMALL SLIVER OF 55 KT GUSTS JUST OFF THE
CENTRAL COAST. WOULD NOT BE SURPRISED TO SEE ISOLATED 55 TO 60 MPH
GUSTS ON EXPOSED HEADLAND AREAS LATE THIS AFTERNOON THROUGH THE
MID-EVENING HOURS...BUT DO NOT THINK THESE WILL BE WIDESPREAD AND
FREQUENT ENOUGH TO WARRANT A WARNING.

THE SYSTEM WILL BRING A 6-9 HR SHOT OF RAIN TO THE AREA...BUT SNOW
LEVELS ARE EXPECTED TO SLOWLY RISE AHEAD OF THE FRONT. THE COLDER
UPPER TROUGH SLIDES ACROSS THE REGION FRI...WITH 1000-500 MB
THICKNESS VALUES DROPPING INTO THE LOW TO MID 530S BY 18Z FRI. THIS
PUTS SNOW LEVELS WELL BELOW THE CASCADE PASSES...BUT BY THIS TIME THE
BULK OF THE PRECIPITATION HAS ALREADY OCCURRED. ALTHOUGH NOT IN THE
FORECAST GRIDS AS OF YET...NEED TO CONSIDER THE POSSIBILITY OF
THUNDERSTORMS FOR FRI. GFS SOUNDING FOR KAST VALID 22Z FRI SHOWS LI
VALUES NEAR 0 BUT A SWEAT INDEX OF 272. THE 1000-750 MB LAPSE RATES
ARE AROUND 7.5C/KM.

MODELS STILL ADVERTISING A CHANGE TO A MUCH WETTER PATTERN STARTING
SAT. NAM AND GFS CONTINUE TO SHOW AN ATMOSPHERIC RIVER SET UP
DIRECTED AT SW WASHINGTON AND NW OREGON SAT. THE GEM MAY BE A BIT
SLOWER...BUT STILL HAS SUBSTANTIAL QPF DIRECTED AT THE FORECAST AREA
BY SAT NIGHT. THE 00Z WRFGFS SHOWS VERY HEAVY QPF WITH UP TO 8-12
INCHES OF RAIN IN THE HIGHER TERRAIN AND 2-4 INCHES IN THE WILLAMETTE
VALLEY SAT THROUGH MONDAY. WILL NEED TO MONITOR THIS VERY CLOSELY
OVER THE NEXT FEW DAYS AS SIMILAR SITUATIONS HAVE PRODUCED FLOODING
ON AREA MAINSTEM RIVERS.  WEISHAAR

LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...MODELS MAINTAIN THE
MILD AND MOIST ATMOSPHERIC RIVER PATTERN THROUGH AT LEAST SUN. THE
ECMWF AND GEM GRADUALLY SHIFT THE FOCUS OF THE HEAVIEST PRECIP TO THE
N SUN AFTERNOON BUT THE GFS DOES NOT. EXPECT PLENTY OF RAINFALL TO
CONTINUE THROUGH SUNDAY. ON MONDAY AND TUESDAY...SOME WEAK RIDGING
MOVES OVER THE REGION BUT SHOWERS LIKELY CONTINUE IN THE MOIST
ONSHORE FLOW. THE ECMWF THEN INDICATES ANOTHER MAJOR PATTERN CHANGE
AROUND THE MIDDLE OF NEXT WEEK WITH A MUCH COLDER AIR MASS SETTLING
OVER THE PAC NW. HOWEVER...MOISTURE DIMINISHES DUE TO THE DRIER N-NE
FLOW. THUS...AFTER WHATEVER SNOW THE CASCADES GET LATE THIS WEEK...IT
WILL BE LOST OVER THE WEEKEND. THE GFS ALSO HAS A CHANGE TO COLDER
NW-N FLOW ALOFT BUT IT MAINTAINS AN OPEN TROUGH INSTEAD OF THE CLOSED
UPPER LOW ECMWF SOLUTION. WHILE STILL SOME SIGNIFICANT UNCERTAINTY
EXISTS WITH RESPECT TO THE TIMING OF THE COLD AIR AND JUST HOW COLD
THE AIR WILL BE...IT DOES APPEAR THAT A CHANGE TO MUCH COOLER
CONDITIONS WILL MOVE INTO THE REGION. SNOW LEVELS SHOULD BE QUITE LOW
OVER THE HOLIDAY...BUT DROPPED POPS SUBSTANTIALLY NEXT THU AND THU
NIGHT. WEISHAAR

&&

.HYDROLOGY...WHILE RIVER FORECASTS OF CURRENT MODEL PRECIPITATION
INDICATE FLOODING IS POSSIBLE ON A RIVER OR TWO IN THE FORECAST AREA
SUNDAY INTO MONDAY...A LOOK AT THE MOST CORRELATED ANALOGS TO THE 96
HOUR GFS MODEL FORECAST SHED LIGHT ON FLOODING CHANCES ACROSS OUR
FORECAST AREA LATE IN THE WEEKEND AND EARLY NEXT WEEK. THE THREE
MOST CORRELATED ANALOG WEATHER PATTERNS TO THE CURRENT 96 HOUR GFS
MODEL FORECAST ARE LATE JANUARY 2003...EARLY JANUARY 1983 AND LATE
NOVEMBER 1999. ALL THREE OF THESE EVENTS PRODUCED ISOLATED TO
SCATTERED RIVER FLOODING WITHIN NORTHWEST OREGON AND/OR SOUTHWEST
WASHINGTON. WHILE THERE ARE CERTAINLY NOTABLE DIFFERENCES BETWEEN
THE CURRENT PATTERN AND EACH OF THESE HISTORICAL ANALOGS...SOME
CRITICAL WEATHER PARAMETERS APPEAR EVEN MORE FAVORABLE FOR PRODUCING
HEAVIER RAINS THAN THESE PAST EVENTS. THIS CERTAINLY HELPS BUILD
CONFIDENCE THERE WILL BE HYDROLOGICAL IMPACTS WITHIN OUR FORECAST
AREA OF RESPONSIBILITY SO LONG AS THE PATTERN HOLDS.
NONETHELESS...THERE IS STILL CONSIDERABLE UNCERTAINTY IN WHERE THE
HEAVIEST RAIN WILL SET UP...AND EXACTLY WHICH RIVERS WILL FLOOD AND
WHEN. PLEASE CONTINUE TO MONITOR THE FORECAST IF YOU LIVE NEAR ANY
RIVERS FED BY THE THE CASCADES OR COAST RANGE...AND PLEASE SEE
WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR FOR THE LATEST RIVER
FORECASTS. /NEUMAN

&&

.AVIATION...MIX OF VFR MVFR WILL CONTINUE THROUGH THE DAY TODAY AS
RAIN MOVES IN ACROSS THE AREA...BRINGING DOWN CIGS AND VIS. FRONT
MOVES ONSHORE AROUND 03Z...REACHING INLAND AROUND 05Z. THIS WILL
BRING PERIODS OF MVFR/IFR CIGS AND VIS WITH LIGHT TO MODERATE
RAIN. CIGS AND VIS TO STAY LOW MVFR/IFR THROUGH EARLY FRIDAY AS
CIGS WILL LIKELY LOWER BEHIND THE COLD FRONT.

KPDX AND APPROACHES...MVFR CIGS LIKELY TO PERSIST THROUGH THIS
MORNING AS RAIN MOVES THROUGH THE AREA. THERE MAY BE A PERIOD
WHERE CIGS LIFT TO VFR AFTER THIS INITIAL BAND...BUT CIGS SHOULD
DROP BACK TO MVFR WITH OCCASIONAL IFR AROUND 05Z AS THE FRONT
BRINGS RAIN THROUGH THE AREA. CIGS AND VIS SHOULD REMAIN MVFR/IFR
OVERNIGHT TONIGHT. -MCCOY

&&

.MARINE...COMBINED SEAS TO STAY AROUND 10 TO 12 FT...POSSIBLY
BUILDING TO NEAR 15 FT AROUND 1 PM TO 8 PM AS WINDS OUT OF THE SOUTH
REACH GALE FORCE WITH GUSTS OF 40 TO 45 KTS LIKELY. SEAS WILL START
TO SUBSIDE TO 10 TO 12 FT LATE THIS EVENING. A 20-22 FT SWELL TRAIN
WITH IMPRESSIVELY LONG PERIODS MOVES IN EARLY FRIDAY MORNING. MODELS
TEND TO UNDER-DO THE WAVE HEIGHTS IN THIS TYPE OF SCENARIO...SO WAVE
HEIGHTS MAY WELL BE UNDERDONE. AS OF NOW...EXPECT SEAS ON FRIDAY
MORNING NEARLY DOUBLE IN HEIGHT BY FRIDAY AFTERNOON. BECAUSE OF
THIS...A HIGH SURF ADVISORY WILL LIKELY BE ISSUED WITH OUR AFTERNOON
PACKAGE TODAY. THE GOOD NEWS IS THAT THE LARGEST SWELL WILL LIKELY
ARRIVE DURING LOW TIDE AND DURING THE NIGHT TIME HOURS WHEN MOST
MARINERS AND BEACH GOERS ARE NOT IN HARMS WAY.

ON SATURDAY MORNING ANOTHER FRONT MOVES THROUGH THE WATERS.
CONFIDENCE IS INCREASING FOR ANOTHER ROUND OF SOUTHERLY GALES...WITH
POSSIBLY SOME LOW END STORM FORCE GUSTS. THIS ON TOP OF THE 20 FT
SWELL SATURDAY COULD EASILY BRING SEAS UP INTO THE MIDDLE 20S LATE
SATURDAY MORNING INTO THE AFTERNOON. BEHIND THIS FRONT...SMALL
CRAFT WINDS OUT OF THE WEST-SOUTHWEST WILL CONTINUE THROUGH THE
DAY ON SUNDAY.

HIGH PRESSURE BUILDS IN EARLY NEXT WEEK BRINGING RELATIVELY BENIGN
WEATHER THROUGH MIDWEEK. -MCCOY

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.

WA...NONE.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 PM PST THIS AFTERNOON FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     GALE WARNING FROM 1 PM THIS AFTERNOON TO MIDNIGHT PST TONIGHT
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 PM PST THIS
     AFTERNOON FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
     FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 6 AM
     PST FRIDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 181216
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
414 AM PST THU DEC 18 2014

.SYNOPSIS...RAIN WILL REDEVELOP BY LATE THIS AFTERNOON AND INCREASE
THURSDAY NIGHT AS A MORE ORGANIZED FRONTAL SYSTEM MOVES ONSHORE. A
COLDER UPPER TROUGH MOVES ACROSS THE AREA FRIDAY...WHICH WILL LOWER
SNOW LEVLES BELOW THE CASCADE PASSES. MILD AND VERY WET WEATHER IS
EXPECTED THIS WEEKEND. THERE IS POTENTIAL FOR AN ATMOSPHERIC RIVER
AND ASSOCIATED HEAVY RAIN TO DEVELOP OVER THE AREA. THE EXACT
LOCATION OF THE JET STREAM AND ASSOCIATED MOISTURE PLUME ARE STILL IN
DOUBT. THERE IS THE POTENTIAL FOR SOME FLOODING LATE THIS
WEEKEND INTO EARLY NEXT WEEK.

&&

.SHORT TERM...THURSDAY THROUGH SATURDAY...WATER VAPOR IMAGERY AS OF
1030Z SHOWS A DEEP UPPER LOW IN THE GULF OF ALASKA WITH A FRONTAL
SYSTEM TAKING SHAPE NEAR 135W. THE 06Z NAM12 RUN SHOWS A WEAK SURFACE
LOW OFF THE S OREGON COAST AT 09Z. THIS FEATURE IS VERY DIFFICULT TO
PICK OUT IN THE WATER VAPOR LOOPER. THE NAM SHOWS THIS LOW FILLING
OVERNIGHT AS IT DRIFTS TO THE NE. NWS PORTLAND DUAL-POL DOPPLER RADAR
SHOWING DECREASING RADAR RETURNS...WITH THE STRONGEST ECHOES IN THE
WILLAPA HILLS AND S WA CASCADES.

NAM...GFS AND ECMWF ALL INDICATE A WEAK 500 MB RIDGE TO MOVE ACROSS
THE AREA TODAY. HOWEVER...MODEL CROSS-SECTIONS AND TIME-HEIGHT
FORECASTS MAINTAIN MOIST LOW-LEVELS THROUGH THE DAY. THUS...STILL
EXPECT LIGHT QPF ACROSS THE FORECAST AREA TODAY...AHEAD OF THE NEXT
FRONTAL SYSTEM. MODELS APPEAR TO BE IN REASONABLE AGREEMENT WITH THIS
FRONT...WITH LANDFALL SOMETIME AROUND 00Z FRI OR SHORTLY THEREAFTER.
ONE CONCERN WAS THE POTENTIAL FOR HIGH WIND ALONG THE COASTAL
HEADLANDS. PREVIOUS SHIFT HAD ISSUED A HIGH WIND WATCH FOR LATE THIS
AFTERNOON THROUGH 08Z FRI. UPON FURTHER REVIEW...NOT SEEING ENOUGH IN
THE 850 MB TO 950 MB WIND FIELDS TO UPGRADE TO A WARNING. THE 00Z
WRF-GFS VALID 00Z FRI HAS A COASTAL JET SIGNATURE OVER THE OREGON
COASTAL WATERS...WITH FORECAST 10M WIND GUSTS OF 55 KT. HOWEVER...BY
03Z FRI THE MODEL HAS JUST A SMALL SLIVER OF 55 KT GUSTS JUST OFF THE
CENTRAL COAST. WOULD NOT BE SURPRISED TO SEE ISOLATED 55 TO 60 MPH
GUSTS ON EXPOSED HEADLAND AREAS LATE THIS AFTERNOON THROUGH THE
MID-EVENING HOURS...BUT DO NOT THINK THESE WILL BE WIDESPREAD AND
FREQUENT ENOUGH TO WARRANT A WARNING.

THE SYSTEM WILL BRING A 6-9 HR SHOT OF RAIN TO THE AREA...BUT SNOW
LEVELS ARE EXPECTED TO SLOWLY RISE AHEAD OF THE FRONT. THE COLDER
UPPER TROUGH SLIDES ACROSS THE REGION FRI...WITH 1000-500 MB
THICKNESS VALUES DROPPING INTO THE LOW TO MID 530S BY 18Z FRI. THIS
PUTS SNOW LEVELS WELL BELOW THE CASCADE PASSES...BUT BY THIS TIME THE
BULK OF THE PRECIPITATION HAS ALREADY OCCURRED. ALTHOUGH NOT IN THE
FORECAST GRIDS AS OF YET...NEED TO CONSIDER THE POSSIBILITY OF
THUNDERSTORMS FOR FRI. GFS SOUNDING FOR KAST VALID 22Z FRI SHOWS LI
VALUES NEAR 0 BUT A SWEAT INDEX OF 272. THE 1000-750 MB LAPSE RATES
ARE AROUND 7.5C/KM.

MODELS STILL ADVERTISING A CHANGE TO A MUCH WETTER PATTERN STARTING
SAT. NAM AND GFS CONTINUE TO SHOW AN ATMOSPHERIC RIVER SET UP
DIRECTED AT SW WASHINGTON AND NW OREGON SAT. THE GEM MAY BE A BIT
SLOWER...BUT STILL HAS SUBSTANTIAL QPF DIRECTED AT THE FORECAST AREA
BY SAT NIGHT. THE 00Z WRFGFS SHOWS VERY HEAVY QPF WITH UP TO 8-12
INCHES OF RAIN IN THE HIGHER TERRAIN AND 2-4 INCHES IN THE WILLAMETTE
VALLEY SAT THROUGH MONDAY. WILL NEED TO MONITOR THIS VERY CLOSELY
OVER THE NEXT FEW DAYS AS SIMILAR SITUATIONS HAVE PRODUCED FLOODING
ON AREA MAINSTEM RIVERS.  WEISHAAR

.HYDROLOGY...WHILE RIVER FORECASTS OF CURRENT MODEL PRECIPITATION
INDICATE FLOODING IS POSSIBLE ON A RIVER OR TWO IN THE FORECAST AREA
SUNDAY INTO MONDAY...A LOOK AT THE MOST CORRELATED ANALOGS TO THE 96
HOUR GFS MODEL FORECAST SHED LIGHT ON FLOODING CHANCES ACROSS OUR
FORECAST AREA LATE IN THE WEEKEND AND EARLY NEXT WEEK. THE THREE
MOST CORRELATED ANALOG WEATHER PATTERNS TO THE CURRENT 96 HOUR GFS
MODEL FORECAST ARE LATE JANUARY 2003...EARLY JANUARY 1983 AND LATE
NOVEMBER 1999. ALL THREE OF THESE EVENTS PRODUCED ISOLATED TO
SCATTERED RIVER FLOODING WITHIN NORTHWEST OREGON AND/OR SOUTHWEST
WASHINGTON. WHILE THERE ARE CERTAINLY NOTABLE DIFFERENCES BETWEEN
THE CURRENT PATTERN AND EACH OF THESE HISTORICAL ANALOGS...SOME
CRITICAL WEATHER PARAMETERS APPEAR EVEN MORE FAVORABLE FOR PRODUCING
HEAVIER RAINS THAN THESE PAST EVENTS. THIS CERTAINLY HELPS BUILD
CONFIDENCE THERE WILL BE HYDROLOGICAL IMPACTS WITHIN OUR FORECAST
AREA OF RESPONSIBILITY SO LONG AS THE PATTERN HOLDS.
NONETHELESS...THERE IS STILL CONSIDERABLE UNCERTAINTY IN WHERE THE
HEAVIEST RAIN WILL SET UP...AND EXACTLY WHICH RIVERS WILL FLOOD AND
WHEN. PLEASE CONTINUE TO MONITOR THE FORECAST IF YOU LIVE NEAR ANY
RIVERS FED BY THE THE CASCADES OR COAST RANGE...AND PLEASE SEE
WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR FOR THE LATEST RIVER
FORECASTS. /NEUMAN

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...MODELS MAINTAIN THE
MILD AND MOIST ATMOSPHERIC RIVER PATTERN THROUGH AT LEAST SUN. THE
ECMWF AND GEM GRADUALLY SHIFT THE FOCUS OF THE HEAVIEST PRECIP TO THE
N SUN AFTERNOON BUT THE GFS DOES NOT. EXPECT PLENTY OF RAINFALL TO
CONTINUE THROUGH SUNDAY. ON MONDAY AND TUESDAY...SOME WEAK RIDGING
MOVES OVER THE REGION BUT SHOWERS LIKELY CONTINUE IN THE MOIST
ONSHORE FLOW. THE ECMWF THEN INDICATES ANOTHER MAJOR PATTERN CHANGE
AROUND THE MIDDLE OF NEXT WEEK WITH A MUCH COLDER AIR MASS SETTLING
OVER THE PAC NW. HOWEVER...MOISTURE DIMINISHES DUE TO THE DRIER N-NE
FLOW. THUS...AFTER WHATEVER SNOW THE CASCADES GET LATE THIS WEEK...IT
WILL BE LOST OVER THE WEEKEND. THE GFS ALSO HAS A CHANGE TO COLDER
NW-N FLOW ALOFT BUT IT MAINTAINS AN OPEN TROUGH INSTEAD OF THE CLOSED
UPPER LOW ECMWF SOLUTION. WHILE STILL SOME SIGNIFICANT UNCERTAINTY
EXISTS WITH RESPECT TO THE TIMING OF THE COLD AIR AND JUST HOW COLD
THE AIR WILL BE...IT DOES APPEAR THAT A CHANGE TO MUCH COOLER
CONDITIONS WILL MOVE INTO THE REGION. SNOW LEVELS SHOULD BE QUITE LOW
OVER THE HOLIDAY...BUT DROPPED POPS SUBSTANTIALLY NEXT THU AND THU
NIGHT. WEISHAAR

&&

.AVIATION...LIGHT WINDS AND A MOIST LOWER ATMOSPHERE WILL CONTINUE
TO BRING A MIX OF IFR TO VFR CONDITIONS THROUGH LATE THURSDAY
MORNING. AS THE NEXT FRONT APPROACHES AND THE WINDS PICK UP AHEAD
OF IT EXPECT MOST TAF SITES TO IMPROVE TO VFR BY THURSDAY
AFTERNOON. THE FRONT WILL LIKELY PUSH INTO THE COAST AROUND 03Z
FRIDAY...AND INTO THE INTERIOR AROUND 06Z FRIDAY. EXPECT BRIEF
PERIODS OF IFR TO MVFR CIGS AND VIS UNDER LIGHT TO MODERATE RAIN
BANDS ASSOCIATED WITH THE FRONT.

KPDX AND APPROACHES...VFR CONDITIONS EXPECTED TO PERSIST THROUGH
FRIDAY MORNING. HOWEVER...BRIEF PERIODS OF MVFR CIGS ARE POSSIBLE
THROUGH LATE THURSDAY MORNING DUE TO A MOIST LOWER ATMOSPHERE. A
FRONT WILL PUSH THROUGH AFTER 06Z FRIDAY AND COULD BRING BRIEF
PERIODS TO IFR TO MVFR CIGS AND VIS UNDER LIGHT TO MODERATE RAIN
BANDS. /64

&&

.MARINE...SEAS CONTINUED TO HOVER AROUND 10 FT OVERNIGHT AND LOOKS
TO REMAIN ELEVATED THROUGHOUT THE MORNING SO THE SMALL CRAFT
ADVISORY FOR HAZARDOUS SEAS WAS EXTENDED TO 1 PM. A STRONG
FRONTAL SYSTEM IS STILL ON TRACK TO MOVE ACROSS THE WATERS TODAY
AND WILL BRING SOLID GALE GUSTS THROUGH THURSDAY NIGHT WITH SEAS
CLIMBING INTO THE MID TEENS. /64

PREVIOUS DISCUSSION FOLLOWS...EXPECT SEAS TO SUBSIDE FAIRLY
QUICKLY BACK DOWN INTO THE 10 TO 12 FT RANGE LATE THURSDAY NIGHT
INTO EARLY FRIDAY MORNING. HOWEVER...THESE LOWER WAVE HEIGHTS WILL
BE SHORT LIVED AS AN IMPRESSIVE LONG PERIOD WESTERLY SWELL WILL
LIKELY ARRIVE FRIDAY AFTERNOON INTO FRIDAY EVENING. WAVE HEIGHTS
MAY NEARLY DOUBLE IN A 6 HOUR PERIOD SO THIS COULD CERTAINLY CATCH
OFF GUARD ANY UNINFORMED MARINERS THAT VENTURE OUT FRIDAY MORNING.
CONFIDENCE IS RELATIVELY HIGH THAT THIS SWELL WILL LIKELY EXCEED
20 FT. IN FACT...THESE PATTERNS OFTEN PRODUCE HIGHER SEAS THAN
FORECASTED BY THE ENP WAVE MODEL. A HIGH SURF ADVISORY APPEARS
LIKELY. THE GOOD NEWS IS THAT THE LARGEST SWELL WILL LIKELY ARRIVE
DURING LOW TIDE AND DURING THE NIGHT TIME HOURS WHEN MOST MARINERS
AND BEACH GOERS ARE NOT IN HARMS WAY.

THIS SWELL TRAIN WILL SUBSIDE SATURDAY...BUT ANOTHER STRONG
FRONTAL STORM SYSTEM WILL LIKELY PRODUCE GALE FORCE TO POSSIBLY
LOW END STORM FORCE GUSTS ACROSS THE WATERS ON SATURDAY. THIS WILL
EFFECTIVELY KEEP SEAS FLIRTING WITH THE 20 FT MARK ON SATURDAY.

NORMAL HIGH TIDE AT TOKE POINT WASHINGTON IS SUPPOSED TO BE 10.3
FT SATURDAY AROUND 11 AM. WITH SOUTHERLY WINDS SUPPORTING A
POSITIVE TIDAL ANOMALY OF AROUND 0.5 FT...HIGH TIDE WILL APPROACH
11 FT AND MAY RESULT IN SOME MINOR TIDAL OVERFLOW FLOODING IN
WILLAPA BAY. GIVEN THE HEAVIER RAINS WILL NOT HAVE ARRIVED...THE
WILLAPA RIVER IS FORECASTED TO BE AROUND 20 PERCENT OF FLOOD
FLOW ON SATURDAY...WHICH SHOULD HELP MITIGATE MORE WIDESPREAD
COASTAL FLOODING CONCERNS.

HIGH PRESSURE WILL SLOWLY BUILD OVER THE NORTHEAST PACIFIC LATE IN
THE WEEKEND AND INTO EARLY NEXT WEEK...WHICH SHOULD RESULT IN
WINDS AND SEAS RELAXING QUITE A BIT WHEN COMPARED TO THE
FRIDAY/SATURDAY TIME FRAME. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.

WA...NONE.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 PM PST THIS AFTERNOON FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     GALE WARNING FROM 1 PM THIS AFTERNOON TO MIDNIGHT PST TONIGHT
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 PM PST THIS
     AFTERNOON FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
     FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 6 AM
     PST FRIDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 181216
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
414 AM PST THU DEC 18 2014

.SYNOPSIS...RAIN WILL REDEVELOP BY LATE THIS AFTERNOON AND INCREASE
THURSDAY NIGHT AS A MORE ORGANIZED FRONTAL SYSTEM MOVES ONSHORE. A
COLDER UPPER TROUGH MOVES ACROSS THE AREA FRIDAY...WHICH WILL LOWER
SNOW LEVLES BELOW THE CASCADE PASSES. MILD AND VERY WET WEATHER IS
EXPECTED THIS WEEKEND. THERE IS POTENTIAL FOR AN ATMOSPHERIC RIVER
AND ASSOCIATED HEAVY RAIN TO DEVELOP OVER THE AREA. THE EXACT
LOCATION OF THE JET STREAM AND ASSOCIATED MOISTURE PLUME ARE STILL IN
DOUBT. THERE IS THE POTENTIAL FOR SOME FLOODING LATE THIS
WEEKEND INTO EARLY NEXT WEEK.

&&

.SHORT TERM...THURSDAY THROUGH SATURDAY...WATER VAPOR IMAGERY AS OF
1030Z SHOWS A DEEP UPPER LOW IN THE GULF OF ALASKA WITH A FRONTAL
SYSTEM TAKING SHAPE NEAR 135W. THE 06Z NAM12 RUN SHOWS A WEAK SURFACE
LOW OFF THE S OREGON COAST AT 09Z. THIS FEATURE IS VERY DIFFICULT TO
PICK OUT IN THE WATER VAPOR LOOPER. THE NAM SHOWS THIS LOW FILLING
OVERNIGHT AS IT DRIFTS TO THE NE. NWS PORTLAND DUAL-POL DOPPLER RADAR
SHOWING DECREASING RADAR RETURNS...WITH THE STRONGEST ECHOES IN THE
WILLAPA HILLS AND S WA CASCADES.

NAM...GFS AND ECMWF ALL INDICATE A WEAK 500 MB RIDGE TO MOVE ACROSS
THE AREA TODAY. HOWEVER...MODEL CROSS-SECTIONS AND TIME-HEIGHT
FORECASTS MAINTAIN MOIST LOW-LEVELS THROUGH THE DAY. THUS...STILL
EXPECT LIGHT QPF ACROSS THE FORECAST AREA TODAY...AHEAD OF THE NEXT
FRONTAL SYSTEM. MODELS APPEAR TO BE IN REASONABLE AGREEMENT WITH THIS
FRONT...WITH LANDFALL SOMETIME AROUND 00Z FRI OR SHORTLY THEREAFTER.
ONE CONCERN WAS THE POTENTIAL FOR HIGH WIND ALONG THE COASTAL
HEADLANDS. PREVIOUS SHIFT HAD ISSUED A HIGH WIND WATCH FOR LATE THIS
AFTERNOON THROUGH 08Z FRI. UPON FURTHER REVIEW...NOT SEEING ENOUGH IN
THE 850 MB TO 950 MB WIND FIELDS TO UPGRADE TO A WARNING. THE 00Z
WRF-GFS VALID 00Z FRI HAS A COASTAL JET SIGNATURE OVER THE OREGON
COASTAL WATERS...WITH FORECAST 10M WIND GUSTS OF 55 KT. HOWEVER...BY
03Z FRI THE MODEL HAS JUST A SMALL SLIVER OF 55 KT GUSTS JUST OFF THE
CENTRAL COAST. WOULD NOT BE SURPRISED TO SEE ISOLATED 55 TO 60 MPH
GUSTS ON EXPOSED HEADLAND AREAS LATE THIS AFTERNOON THROUGH THE
MID-EVENING HOURS...BUT DO NOT THINK THESE WILL BE WIDESPREAD AND
FREQUENT ENOUGH TO WARRANT A WARNING.

THE SYSTEM WILL BRING A 6-9 HR SHOT OF RAIN TO THE AREA...BUT SNOW
LEVELS ARE EXPECTED TO SLOWLY RISE AHEAD OF THE FRONT. THE COLDER
UPPER TROUGH SLIDES ACROSS THE REGION FRI...WITH 1000-500 MB
THICKNESS VALUES DROPPING INTO THE LOW TO MID 530S BY 18Z FRI. THIS
PUTS SNOW LEVELS WELL BELOW THE CASCADE PASSES...BUT BY THIS TIME THE
BULK OF THE PRECIPITATION HAS ALREADY OCCURRED. ALTHOUGH NOT IN THE
FORECAST GRIDS AS OF YET...NEED TO CONSIDER THE POSSIBILITY OF
THUNDERSTORMS FOR FRI. GFS SOUNDING FOR KAST VALID 22Z FRI SHOWS LI
VALUES NEAR 0 BUT A SWEAT INDEX OF 272. THE 1000-750 MB LAPSE RATES
ARE AROUND 7.5C/KM.

MODELS STILL ADVERTISING A CHANGE TO A MUCH WETTER PATTERN STARTING
SAT. NAM AND GFS CONTINUE TO SHOW AN ATMOSPHERIC RIVER SET UP
DIRECTED AT SW WASHINGTON AND NW OREGON SAT. THE GEM MAY BE A BIT
SLOWER...BUT STILL HAS SUBSTANTIAL QPF DIRECTED AT THE FORECAST AREA
BY SAT NIGHT. THE 00Z WRFGFS SHOWS VERY HEAVY QPF WITH UP TO 8-12
INCHES OF RAIN IN THE HIGHER TERRAIN AND 2-4 INCHES IN THE WILLAMETTE
VALLEY SAT THROUGH MONDAY. WILL NEED TO MONITOR THIS VERY CLOSELY
OVER THE NEXT FEW DAYS AS SIMILAR SITUATIONS HAVE PRODUCED FLOODING
ON AREA MAINSTEM RIVERS.  WEISHAAR

.HYDROLOGY...WHILE RIVER FORECASTS OF CURRENT MODEL PRECIPITATION
INDICATE FLOODING IS POSSIBLE ON A RIVER OR TWO IN THE FORECAST AREA
SUNDAY INTO MONDAY...A LOOK AT THE MOST CORRELATED ANALOGS TO THE 96
HOUR GFS MODEL FORECAST SHED LIGHT ON FLOODING CHANCES ACROSS OUR
FORECAST AREA LATE IN THE WEEKEND AND EARLY NEXT WEEK. THE THREE
MOST CORRELATED ANALOG WEATHER PATTERNS TO THE CURRENT 96 HOUR GFS
MODEL FORECAST ARE LATE JANUARY 2003...EARLY JANUARY 1983 AND LATE
NOVEMBER 1999. ALL THREE OF THESE EVENTS PRODUCED ISOLATED TO
SCATTERED RIVER FLOODING WITHIN NORTHWEST OREGON AND/OR SOUTHWEST
WASHINGTON. WHILE THERE ARE CERTAINLY NOTABLE DIFFERENCES BETWEEN
THE CURRENT PATTERN AND EACH OF THESE HISTORICAL ANALOGS...SOME
CRITICAL WEATHER PARAMETERS APPEAR EVEN MORE FAVORABLE FOR PRODUCING
HEAVIER RAINS THAN THESE PAST EVENTS. THIS CERTAINLY HELPS BUILD
CONFIDENCE THERE WILL BE HYDROLOGICAL IMPACTS WITHIN OUR FORECAST
AREA OF RESPONSIBILITY SO LONG AS THE PATTERN HOLDS.
NONETHELESS...THERE IS STILL CONSIDERABLE UNCERTAINTY IN WHERE THE
HEAVIEST RAIN WILL SET UP...AND EXACTLY WHICH RIVERS WILL FLOOD AND
WHEN. PLEASE CONTINUE TO MONITOR THE FORECAST IF YOU LIVE NEAR ANY
RIVERS FED BY THE THE CASCADES OR COAST RANGE...AND PLEASE SEE
WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR FOR THE LATEST RIVER
FORECASTS. /NEUMAN

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...MODELS MAINTAIN THE
MILD AND MOIST ATMOSPHERIC RIVER PATTERN THROUGH AT LEAST SUN. THE
ECMWF AND GEM GRADUALLY SHIFT THE FOCUS OF THE HEAVIEST PRECIP TO THE
N SUN AFTERNOON BUT THE GFS DOES NOT. EXPECT PLENTY OF RAINFALL TO
CONTINUE THROUGH SUNDAY. ON MONDAY AND TUESDAY...SOME WEAK RIDGING
MOVES OVER THE REGION BUT SHOWERS LIKELY CONTINUE IN THE MOIST
ONSHORE FLOW. THE ECMWF THEN INDICATES ANOTHER MAJOR PATTERN CHANGE
AROUND THE MIDDLE OF NEXT WEEK WITH A MUCH COLDER AIR MASS SETTLING
OVER THE PAC NW. HOWEVER...MOISTURE DIMINISHES DUE TO THE DRIER N-NE
FLOW. THUS...AFTER WHATEVER SNOW THE CASCADES GET LATE THIS WEEK...IT
WILL BE LOST OVER THE WEEKEND. THE GFS ALSO HAS A CHANGE TO COLDER
NW-N FLOW ALOFT BUT IT MAINTAINS AN OPEN TROUGH INSTEAD OF THE CLOSED
UPPER LOW ECMWF SOLUTION. WHILE STILL SOME SIGNIFICANT UNCERTAINTY
EXISTS WITH RESPECT TO THE TIMING OF THE COLD AIR AND JUST HOW COLD
THE AIR WILL BE...IT DOES APPEAR THAT A CHANGE TO MUCH COOLER
CONDITIONS WILL MOVE INTO THE REGION. SNOW LEVELS SHOULD BE QUITE LOW
OVER THE HOLIDAY...BUT DROPPED POPS SUBSTANTIALLY NEXT THU AND THU
NIGHT. WEISHAAR

&&

.AVIATION...LIGHT WINDS AND A MOIST LOWER ATMOSPHERE WILL CONTINUE
TO BRING A MIX OF IFR TO VFR CONDITIONS THROUGH LATE THURSDAY
MORNING. AS THE NEXT FRONT APPROACHES AND THE WINDS PICK UP AHEAD
OF IT EXPECT MOST TAF SITES TO IMPROVE TO VFR BY THURSDAY
AFTERNOON. THE FRONT WILL LIKELY PUSH INTO THE COAST AROUND 03Z
FRIDAY...AND INTO THE INTERIOR AROUND 06Z FRIDAY. EXPECT BRIEF
PERIODS OF IFR TO MVFR CIGS AND VIS UNDER LIGHT TO MODERATE RAIN
BANDS ASSOCIATED WITH THE FRONT.

KPDX AND APPROACHES...VFR CONDITIONS EXPECTED TO PERSIST THROUGH
FRIDAY MORNING. HOWEVER...BRIEF PERIODS OF MVFR CIGS ARE POSSIBLE
THROUGH LATE THURSDAY MORNING DUE TO A MOIST LOWER ATMOSPHERE. A
FRONT WILL PUSH THROUGH AFTER 06Z FRIDAY AND COULD BRING BRIEF
PERIODS TO IFR TO MVFR CIGS AND VIS UNDER LIGHT TO MODERATE RAIN
BANDS. /64

&&

.MARINE...SEAS CONTINUED TO HOVER AROUND 10 FT OVERNIGHT AND LOOKS
TO REMAIN ELEVATED THROUGHOUT THE MORNING SO THE SMALL CRAFT
ADVISORY FOR HAZARDOUS SEAS WAS EXTENDED TO 1 PM. A STRONG
FRONTAL SYSTEM IS STILL ON TRACK TO MOVE ACROSS THE WATERS TODAY
AND WILL BRING SOLID GALE GUSTS THROUGH THURSDAY NIGHT WITH SEAS
CLIMBING INTO THE MID TEENS. /64

PREVIOUS DISCUSSION FOLLOWS...EXPECT SEAS TO SUBSIDE FAIRLY
QUICKLY BACK DOWN INTO THE 10 TO 12 FT RANGE LATE THURSDAY NIGHT
INTO EARLY FRIDAY MORNING. HOWEVER...THESE LOWER WAVE HEIGHTS WILL
BE SHORT LIVED AS AN IMPRESSIVE LONG PERIOD WESTERLY SWELL WILL
LIKELY ARRIVE FRIDAY AFTERNOON INTO FRIDAY EVENING. WAVE HEIGHTS
MAY NEARLY DOUBLE IN A 6 HOUR PERIOD SO THIS COULD CERTAINLY CATCH
OFF GUARD ANY UNINFORMED MARINERS THAT VENTURE OUT FRIDAY MORNING.
CONFIDENCE IS RELATIVELY HIGH THAT THIS SWELL WILL LIKELY EXCEED
20 FT. IN FACT...THESE PATTERNS OFTEN PRODUCE HIGHER SEAS THAN
FORECASTED BY THE ENP WAVE MODEL. A HIGH SURF ADVISORY APPEARS
LIKELY. THE GOOD NEWS IS THAT THE LARGEST SWELL WILL LIKELY ARRIVE
DURING LOW TIDE AND DURING THE NIGHT TIME HOURS WHEN MOST MARINERS
AND BEACH GOERS ARE NOT IN HARMS WAY.

THIS SWELL TRAIN WILL SUBSIDE SATURDAY...BUT ANOTHER STRONG
FRONTAL STORM SYSTEM WILL LIKELY PRODUCE GALE FORCE TO POSSIBLY
LOW END STORM FORCE GUSTS ACROSS THE WATERS ON SATURDAY. THIS WILL
EFFECTIVELY KEEP SEAS FLIRTING WITH THE 20 FT MARK ON SATURDAY.

NORMAL HIGH TIDE AT TOKE POINT WASHINGTON IS SUPPOSED TO BE 10.3
FT SATURDAY AROUND 11 AM. WITH SOUTHERLY WINDS SUPPORTING A
POSITIVE TIDAL ANOMALY OF AROUND 0.5 FT...HIGH TIDE WILL APPROACH
11 FT AND MAY RESULT IN SOME MINOR TIDAL OVERFLOW FLOODING IN
WILLAPA BAY. GIVEN THE HEAVIER RAINS WILL NOT HAVE ARRIVED...THE
WILLAPA RIVER IS FORECASTED TO BE AROUND 20 PERCENT OF FLOOD
FLOW ON SATURDAY...WHICH SHOULD HELP MITIGATE MORE WIDESPREAD
COASTAL FLOODING CONCERNS.

HIGH PRESSURE WILL SLOWLY BUILD OVER THE NORTHEAST PACIFIC LATE IN
THE WEEKEND AND INTO EARLY NEXT WEEK...WHICH SHOULD RESULT IN
WINDS AND SEAS RELAXING QUITE A BIT WHEN COMPARED TO THE
FRIDAY/SATURDAY TIME FRAME. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.

WA...NONE.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 PM PST THIS AFTERNOON FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     GALE WARNING FROM 1 PM THIS AFTERNOON TO MIDNIGHT PST TONIGHT
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 PM PST THIS
     AFTERNOON FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
     FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 6 AM
     PST FRIDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.





000
FXUS66 KPQR 181216
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
414 AM PST THU DEC 18 2014

.SYNOPSIS...RAIN WILL REDEVELOP BY LATE THIS AFTERNOON AND INCREASE
THURSDAY NIGHT AS A MORE ORGANIZED FRONTAL SYSTEM MOVES ONSHORE. A
COLDER UPPER TROUGH MOVES ACROSS THE AREA FRIDAY...WHICH WILL LOWER
SNOW LEVLES BELOW THE CASCADE PASSES. MILD AND VERY WET WEATHER IS
EXPECTED THIS WEEKEND. THERE IS POTENTIAL FOR AN ATMOSPHERIC RIVER
AND ASSOCIATED HEAVY RAIN TO DEVELOP OVER THE AREA. THE EXACT
LOCATION OF THE JET STREAM AND ASSOCIATED MOISTURE PLUME ARE STILL IN
DOUBT. THERE IS THE POTENTIAL FOR SOME FLOODING LATE THIS
WEEKEND INTO EARLY NEXT WEEK.

&&

.SHORT TERM...THURSDAY THROUGH SATURDAY...WATER VAPOR IMAGERY AS OF
1030Z SHOWS A DEEP UPPER LOW IN THE GULF OF ALASKA WITH A FRONTAL
SYSTEM TAKING SHAPE NEAR 135W. THE 06Z NAM12 RUN SHOWS A WEAK SURFACE
LOW OFF THE S OREGON COAST AT 09Z. THIS FEATURE IS VERY DIFFICULT TO
PICK OUT IN THE WATER VAPOR LOOPER. THE NAM SHOWS THIS LOW FILLING
OVERNIGHT AS IT DRIFTS TO THE NE. NWS PORTLAND DUAL-POL DOPPLER RADAR
SHOWING DECREASING RADAR RETURNS...WITH THE STRONGEST ECHOES IN THE
WILLAPA HILLS AND S WA CASCADES.

NAM...GFS AND ECMWF ALL INDICATE A WEAK 500 MB RIDGE TO MOVE ACROSS
THE AREA TODAY. HOWEVER...MODEL CROSS-SECTIONS AND TIME-HEIGHT
FORECASTS MAINTAIN MOIST LOW-LEVELS THROUGH THE DAY. THUS...STILL
EXPECT LIGHT QPF ACROSS THE FORECAST AREA TODAY...AHEAD OF THE NEXT
FRONTAL SYSTEM. MODELS APPEAR TO BE IN REASONABLE AGREEMENT WITH THIS
FRONT...WITH LANDFALL SOMETIME AROUND 00Z FRI OR SHORTLY THEREAFTER.
ONE CONCERN WAS THE POTENTIAL FOR HIGH WIND ALONG THE COASTAL
HEADLANDS. PREVIOUS SHIFT HAD ISSUED A HIGH WIND WATCH FOR LATE THIS
AFTERNOON THROUGH 08Z FRI. UPON FURTHER REVIEW...NOT SEEING ENOUGH IN
THE 850 MB TO 950 MB WIND FIELDS TO UPGRADE TO A WARNING. THE 00Z
WRF-GFS VALID 00Z FRI HAS A COASTAL JET SIGNATURE OVER THE OREGON
COASTAL WATERS...WITH FORECAST 10M WIND GUSTS OF 55 KT. HOWEVER...BY
03Z FRI THE MODEL HAS JUST A SMALL SLIVER OF 55 KT GUSTS JUST OFF THE
CENTRAL COAST. WOULD NOT BE SURPRISED TO SEE ISOLATED 55 TO 60 MPH
GUSTS ON EXPOSED HEADLAND AREAS LATE THIS AFTERNOON THROUGH THE
MID-EVENING HOURS...BUT DO NOT THINK THESE WILL BE WIDESPREAD AND
FREQUENT ENOUGH TO WARRANT A WARNING.

THE SYSTEM WILL BRING A 6-9 HR SHOT OF RAIN TO THE AREA...BUT SNOW
LEVELS ARE EXPECTED TO SLOWLY RISE AHEAD OF THE FRONT. THE COLDER
UPPER TROUGH SLIDES ACROSS THE REGION FRI...WITH 1000-500 MB
THICKNESS VALUES DROPPING INTO THE LOW TO MID 530S BY 18Z FRI. THIS
PUTS SNOW LEVELS WELL BELOW THE CASCADE PASSES...BUT BY THIS TIME THE
BULK OF THE PRECIPITATION HAS ALREADY OCCURRED. ALTHOUGH NOT IN THE
FORECAST GRIDS AS OF YET...NEED TO CONSIDER THE POSSIBILITY OF
THUNDERSTORMS FOR FRI. GFS SOUNDING FOR KAST VALID 22Z FRI SHOWS LI
VALUES NEAR 0 BUT A SWEAT INDEX OF 272. THE 1000-750 MB LAPSE RATES
ARE AROUND 7.5C/KM.

MODELS STILL ADVERTISING A CHANGE TO A MUCH WETTER PATTERN STARTING
SAT. NAM AND GFS CONTINUE TO SHOW AN ATMOSPHERIC RIVER SET UP
DIRECTED AT SW WASHINGTON AND NW OREGON SAT. THE GEM MAY BE A BIT
SLOWER...BUT STILL HAS SUBSTANTIAL QPF DIRECTED AT THE FORECAST AREA
BY SAT NIGHT. THE 00Z WRFGFS SHOWS VERY HEAVY QPF WITH UP TO 8-12
INCHES OF RAIN IN THE HIGHER TERRAIN AND 2-4 INCHES IN THE WILLAMETTE
VALLEY SAT THROUGH MONDAY. WILL NEED TO MONITOR THIS VERY CLOSELY
OVER THE NEXT FEW DAYS AS SIMILAR SITUATIONS HAVE PRODUCED FLOODING
ON AREA MAINSTEM RIVERS.  WEISHAAR

.HYDROLOGY...WHILE RIVER FORECASTS OF CURRENT MODEL PRECIPITATION
INDICATE FLOODING IS POSSIBLE ON A RIVER OR TWO IN THE FORECAST AREA
SUNDAY INTO MONDAY...A LOOK AT THE MOST CORRELATED ANALOGS TO THE 96
HOUR GFS MODEL FORECAST SHED LIGHT ON FLOODING CHANCES ACROSS OUR
FORECAST AREA LATE IN THE WEEKEND AND EARLY NEXT WEEK. THE THREE
MOST CORRELATED ANALOG WEATHER PATTERNS TO THE CURRENT 96 HOUR GFS
MODEL FORECAST ARE LATE JANUARY 2003...EARLY JANUARY 1983 AND LATE
NOVEMBER 1999. ALL THREE OF THESE EVENTS PRODUCED ISOLATED TO
SCATTERED RIVER FLOODING WITHIN NORTHWEST OREGON AND/OR SOUTHWEST
WASHINGTON. WHILE THERE ARE CERTAINLY NOTABLE DIFFERENCES BETWEEN
THE CURRENT PATTERN AND EACH OF THESE HISTORICAL ANALOGS...SOME
CRITICAL WEATHER PARAMETERS APPEAR EVEN MORE FAVORABLE FOR PRODUCING
HEAVIER RAINS THAN THESE PAST EVENTS. THIS CERTAINLY HELPS BUILD
CONFIDENCE THERE WILL BE HYDROLOGICAL IMPACTS WITHIN OUR FORECAST
AREA OF RESPONSIBILITY SO LONG AS THE PATTERN HOLDS.
NONETHELESS...THERE IS STILL CONSIDERABLE UNCERTAINTY IN WHERE THE
HEAVIEST RAIN WILL SET UP...AND EXACTLY WHICH RIVERS WILL FLOOD AND
WHEN. PLEASE CONTINUE TO MONITOR THE FORECAST IF YOU LIVE NEAR ANY
RIVERS FED BY THE THE CASCADES OR COAST RANGE...AND PLEASE SEE
WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR FOR THE LATEST RIVER
FORECASTS. /NEUMAN

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...MODELS MAINTAIN THE
MILD AND MOIST ATMOSPHERIC RIVER PATTERN THROUGH AT LEAST SUN. THE
ECMWF AND GEM GRADUALLY SHIFT THE FOCUS OF THE HEAVIEST PRECIP TO THE
N SUN AFTERNOON BUT THE GFS DOES NOT. EXPECT PLENTY OF RAINFALL TO
CONTINUE THROUGH SUNDAY. ON MONDAY AND TUESDAY...SOME WEAK RIDGING
MOVES OVER THE REGION BUT SHOWERS LIKELY CONTINUE IN THE MOIST
ONSHORE FLOW. THE ECMWF THEN INDICATES ANOTHER MAJOR PATTERN CHANGE
AROUND THE MIDDLE OF NEXT WEEK WITH A MUCH COLDER AIR MASS SETTLING
OVER THE PAC NW. HOWEVER...MOISTURE DIMINISHES DUE TO THE DRIER N-NE
FLOW. THUS...AFTER WHATEVER SNOW THE CASCADES GET LATE THIS WEEK...IT
WILL BE LOST OVER THE WEEKEND. THE GFS ALSO HAS A CHANGE TO COLDER
NW-N FLOW ALOFT BUT IT MAINTAINS AN OPEN TROUGH INSTEAD OF THE CLOSED
UPPER LOW ECMWF SOLUTION. WHILE STILL SOME SIGNIFICANT UNCERTAINTY
EXISTS WITH RESPECT TO THE TIMING OF THE COLD AIR AND JUST HOW COLD
THE AIR WILL BE...IT DOES APPEAR THAT A CHANGE TO MUCH COOLER
CONDITIONS WILL MOVE INTO THE REGION. SNOW LEVELS SHOULD BE QUITE LOW
OVER THE HOLIDAY...BUT DROPPED POPS SUBSTANTIALLY NEXT THU AND THU
NIGHT. WEISHAAR

&&

.AVIATION...LIGHT WINDS AND A MOIST LOWER ATMOSPHERE WILL CONTINUE
TO BRING A MIX OF IFR TO VFR CONDITIONS THROUGH LATE THURSDAY
MORNING. AS THE NEXT FRONT APPROACHES AND THE WINDS PICK UP AHEAD
OF IT EXPECT MOST TAF SITES TO IMPROVE TO VFR BY THURSDAY
AFTERNOON. THE FRONT WILL LIKELY PUSH INTO THE COAST AROUND 03Z
FRIDAY...AND INTO THE INTERIOR AROUND 06Z FRIDAY. EXPECT BRIEF
PERIODS OF IFR TO MVFR CIGS AND VIS UNDER LIGHT TO MODERATE RAIN
BANDS ASSOCIATED WITH THE FRONT.

KPDX AND APPROACHES...VFR CONDITIONS EXPECTED TO PERSIST THROUGH
FRIDAY MORNING. HOWEVER...BRIEF PERIODS OF MVFR CIGS ARE POSSIBLE
THROUGH LATE THURSDAY MORNING DUE TO A MOIST LOWER ATMOSPHERE. A
FRONT WILL PUSH THROUGH AFTER 06Z FRIDAY AND COULD BRING BRIEF
PERIODS TO IFR TO MVFR CIGS AND VIS UNDER LIGHT TO MODERATE RAIN
BANDS. /64

&&

.MARINE...SEAS CONTINUED TO HOVER AROUND 10 FT OVERNIGHT AND LOOKS
TO REMAIN ELEVATED THROUGHOUT THE MORNING SO THE SMALL CRAFT
ADVISORY FOR HAZARDOUS SEAS WAS EXTENDED TO 1 PM. A STRONG
FRONTAL SYSTEM IS STILL ON TRACK TO MOVE ACROSS THE WATERS TODAY
AND WILL BRING SOLID GALE GUSTS THROUGH THURSDAY NIGHT WITH SEAS
CLIMBING INTO THE MID TEENS. /64

PREVIOUS DISCUSSION FOLLOWS...EXPECT SEAS TO SUBSIDE FAIRLY
QUICKLY BACK DOWN INTO THE 10 TO 12 FT RANGE LATE THURSDAY NIGHT
INTO EARLY FRIDAY MORNING. HOWEVER...THESE LOWER WAVE HEIGHTS WILL
BE SHORT LIVED AS AN IMPRESSIVE LONG PERIOD WESTERLY SWELL WILL
LIKELY ARRIVE FRIDAY AFTERNOON INTO FRIDAY EVENING. WAVE HEIGHTS
MAY NEARLY DOUBLE IN A 6 HOUR PERIOD SO THIS COULD CERTAINLY CATCH
OFF GUARD ANY UNINFORMED MARINERS THAT VENTURE OUT FRIDAY MORNING.
CONFIDENCE IS RELATIVELY HIGH THAT THIS SWELL WILL LIKELY EXCEED
20 FT. IN FACT...THESE PATTERNS OFTEN PRODUCE HIGHER SEAS THAN
FORECASTED BY THE ENP WAVE MODEL. A HIGH SURF ADVISORY APPEARS
LIKELY. THE GOOD NEWS IS THAT THE LARGEST SWELL WILL LIKELY ARRIVE
DURING LOW TIDE AND DURING THE NIGHT TIME HOURS WHEN MOST MARINERS
AND BEACH GOERS ARE NOT IN HARMS WAY.

THIS SWELL TRAIN WILL SUBSIDE SATURDAY...BUT ANOTHER STRONG
FRONTAL STORM SYSTEM WILL LIKELY PRODUCE GALE FORCE TO POSSIBLY
LOW END STORM FORCE GUSTS ACROSS THE WATERS ON SATURDAY. THIS WILL
EFFECTIVELY KEEP SEAS FLIRTING WITH THE 20 FT MARK ON SATURDAY.

NORMAL HIGH TIDE AT TOKE POINT WASHINGTON IS SUPPOSED TO BE 10.3
FT SATURDAY AROUND 11 AM. WITH SOUTHERLY WINDS SUPPORTING A
POSITIVE TIDAL ANOMALY OF AROUND 0.5 FT...HIGH TIDE WILL APPROACH
11 FT AND MAY RESULT IN SOME MINOR TIDAL OVERFLOW FLOODING IN
WILLAPA BAY. GIVEN THE HEAVIER RAINS WILL NOT HAVE ARRIVED...THE
WILLAPA RIVER IS FORECASTED TO BE AROUND 20 PERCENT OF FLOOD
FLOW ON SATURDAY...WHICH SHOULD HELP MITIGATE MORE WIDESPREAD
COASTAL FLOODING CONCERNS.

HIGH PRESSURE WILL SLOWLY BUILD OVER THE NORTHEAST PACIFIC LATE IN
THE WEEKEND AND INTO EARLY NEXT WEEK...WHICH SHOULD RESULT IN
WINDS AND SEAS RELAXING QUITE A BIT WHEN COMPARED TO THE
FRIDAY/SATURDAY TIME FRAME. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.

WA...NONE.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 PM PST THIS AFTERNOON FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     GALE WARNING FROM 1 PM THIS AFTERNOON TO MIDNIGHT PST TONIGHT
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 PM PST THIS
     AFTERNOON FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
     FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 6 AM
     PST FRIDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.





000
FXUS66 KPQR 181216
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
414 AM PST THU DEC 18 2014

.SYNOPSIS...RAIN WILL REDEVELOP BY LATE THIS AFTERNOON AND INCREASE
THURSDAY NIGHT AS A MORE ORGANIZED FRONTAL SYSTEM MOVES ONSHORE. A
COLDER UPPER TROUGH MOVES ACROSS THE AREA FRIDAY...WHICH WILL LOWER
SNOW LEVLES BELOW THE CASCADE PASSES. MILD AND VERY WET WEATHER IS
EXPECTED THIS WEEKEND. THERE IS POTENTIAL FOR AN ATMOSPHERIC RIVER
AND ASSOCIATED HEAVY RAIN TO DEVELOP OVER THE AREA. THE EXACT
LOCATION OF THE JET STREAM AND ASSOCIATED MOISTURE PLUME ARE STILL IN
DOUBT. THERE IS THE POTENTIAL FOR SOME FLOODING LATE THIS
WEEKEND INTO EARLY NEXT WEEK.

&&

.SHORT TERM...THURSDAY THROUGH SATURDAY...WATER VAPOR IMAGERY AS OF
1030Z SHOWS A DEEP UPPER LOW IN THE GULF OF ALASKA WITH A FRONTAL
SYSTEM TAKING SHAPE NEAR 135W. THE 06Z NAM12 RUN SHOWS A WEAK SURFACE
LOW OFF THE S OREGON COAST AT 09Z. THIS FEATURE IS VERY DIFFICULT TO
PICK OUT IN THE WATER VAPOR LOOPER. THE NAM SHOWS THIS LOW FILLING
OVERNIGHT AS IT DRIFTS TO THE NE. NWS PORTLAND DUAL-POL DOPPLER RADAR
SHOWING DECREASING RADAR RETURNS...WITH THE STRONGEST ECHOES IN THE
WILLAPA HILLS AND S WA CASCADES.

NAM...GFS AND ECMWF ALL INDICATE A WEAK 500 MB RIDGE TO MOVE ACROSS
THE AREA TODAY. HOWEVER...MODEL CROSS-SECTIONS AND TIME-HEIGHT
FORECASTS MAINTAIN MOIST LOW-LEVELS THROUGH THE DAY. THUS...STILL
EXPECT LIGHT QPF ACROSS THE FORECAST AREA TODAY...AHEAD OF THE NEXT
FRONTAL SYSTEM. MODELS APPEAR TO BE IN REASONABLE AGREEMENT WITH THIS
FRONT...WITH LANDFALL SOMETIME AROUND 00Z FRI OR SHORTLY THEREAFTER.
ONE CONCERN WAS THE POTENTIAL FOR HIGH WIND ALONG THE COASTAL
HEADLANDS. PREVIOUS SHIFT HAD ISSUED A HIGH WIND WATCH FOR LATE THIS
AFTERNOON THROUGH 08Z FRI. UPON FURTHER REVIEW...NOT SEEING ENOUGH IN
THE 850 MB TO 950 MB WIND FIELDS TO UPGRADE TO A WARNING. THE 00Z
WRF-GFS VALID 00Z FRI HAS A COASTAL JET SIGNATURE OVER THE OREGON
COASTAL WATERS...WITH FORECAST 10M WIND GUSTS OF 55 KT. HOWEVER...BY
03Z FRI THE MODEL HAS JUST A SMALL SLIVER OF 55 KT GUSTS JUST OFF THE
CENTRAL COAST. WOULD NOT BE SURPRISED TO SEE ISOLATED 55 TO 60 MPH
GUSTS ON EXPOSED HEADLAND AREAS LATE THIS AFTERNOON THROUGH THE
MID-EVENING HOURS...BUT DO NOT THINK THESE WILL BE WIDESPREAD AND
FREQUENT ENOUGH TO WARRANT A WARNING.

THE SYSTEM WILL BRING A 6-9 HR SHOT OF RAIN TO THE AREA...BUT SNOW
LEVELS ARE EXPECTED TO SLOWLY RISE AHEAD OF THE FRONT. THE COLDER
UPPER TROUGH SLIDES ACROSS THE REGION FRI...WITH 1000-500 MB
THICKNESS VALUES DROPPING INTO THE LOW TO MID 530S BY 18Z FRI. THIS
PUTS SNOW LEVELS WELL BELOW THE CASCADE PASSES...BUT BY THIS TIME THE
BULK OF THE PRECIPITATION HAS ALREADY OCCURRED. ALTHOUGH NOT IN THE
FORECAST GRIDS AS OF YET...NEED TO CONSIDER THE POSSIBILITY OF
THUNDERSTORMS FOR FRI. GFS SOUNDING FOR KAST VALID 22Z FRI SHOWS LI
VALUES NEAR 0 BUT A SWEAT INDEX OF 272. THE 1000-750 MB LAPSE RATES
ARE AROUND 7.5C/KM.

MODELS STILL ADVERTISING A CHANGE TO A MUCH WETTER PATTERN STARTING
SAT. NAM AND GFS CONTINUE TO SHOW AN ATMOSPHERIC RIVER SET UP
DIRECTED AT SW WASHINGTON AND NW OREGON SAT. THE GEM MAY BE A BIT
SLOWER...BUT STILL HAS SUBSTANTIAL QPF DIRECTED AT THE FORECAST AREA
BY SAT NIGHT. THE 00Z WRFGFS SHOWS VERY HEAVY QPF WITH UP TO 8-12
INCHES OF RAIN IN THE HIGHER TERRAIN AND 2-4 INCHES IN THE WILLAMETTE
VALLEY SAT THROUGH MONDAY. WILL NEED TO MONITOR THIS VERY CLOSELY
OVER THE NEXT FEW DAYS AS SIMILAR SITUATIONS HAVE PRODUCED FLOODING
ON AREA MAINSTEM RIVERS.  WEISHAAR

.HYDROLOGY...WHILE RIVER FORECASTS OF CURRENT MODEL PRECIPITATION
INDICATE FLOODING IS POSSIBLE ON A RIVER OR TWO IN THE FORECAST AREA
SUNDAY INTO MONDAY...A LOOK AT THE MOST CORRELATED ANALOGS TO THE 96
HOUR GFS MODEL FORECAST SHED LIGHT ON FLOODING CHANCES ACROSS OUR
FORECAST AREA LATE IN THE WEEKEND AND EARLY NEXT WEEK. THE THREE
MOST CORRELATED ANALOG WEATHER PATTERNS TO THE CURRENT 96 HOUR GFS
MODEL FORECAST ARE LATE JANUARY 2003...EARLY JANUARY 1983 AND LATE
NOVEMBER 1999. ALL THREE OF THESE EVENTS PRODUCED ISOLATED TO
SCATTERED RIVER FLOODING WITHIN NORTHWEST OREGON AND/OR SOUTHWEST
WASHINGTON. WHILE THERE ARE CERTAINLY NOTABLE DIFFERENCES BETWEEN
THE CURRENT PATTERN AND EACH OF THESE HISTORICAL ANALOGS...SOME
CRITICAL WEATHER PARAMETERS APPEAR EVEN MORE FAVORABLE FOR PRODUCING
HEAVIER RAINS THAN THESE PAST EVENTS. THIS CERTAINLY HELPS BUILD
CONFIDENCE THERE WILL BE HYDROLOGICAL IMPACTS WITHIN OUR FORECAST
AREA OF RESPONSIBILITY SO LONG AS THE PATTERN HOLDS.
NONETHELESS...THERE IS STILL CONSIDERABLE UNCERTAINTY IN WHERE THE
HEAVIEST RAIN WILL SET UP...AND EXACTLY WHICH RIVERS WILL FLOOD AND
WHEN. PLEASE CONTINUE TO MONITOR THE FORECAST IF YOU LIVE NEAR ANY
RIVERS FED BY THE THE CASCADES OR COAST RANGE...AND PLEASE SEE
WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR FOR THE LATEST RIVER
FORECASTS. /NEUMAN

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...MODELS MAINTAIN THE
MILD AND MOIST ATMOSPHERIC RIVER PATTERN THROUGH AT LEAST SUN. THE
ECMWF AND GEM GRADUALLY SHIFT THE FOCUS OF THE HEAVIEST PRECIP TO THE
N SUN AFTERNOON BUT THE GFS DOES NOT. EXPECT PLENTY OF RAINFALL TO
CONTINUE THROUGH SUNDAY. ON MONDAY AND TUESDAY...SOME WEAK RIDGING
MOVES OVER THE REGION BUT SHOWERS LIKELY CONTINUE IN THE MOIST
ONSHORE FLOW. THE ECMWF THEN INDICATES ANOTHER MAJOR PATTERN CHANGE
AROUND THE MIDDLE OF NEXT WEEK WITH A MUCH COLDER AIR MASS SETTLING
OVER THE PAC NW. HOWEVER...MOISTURE DIMINISHES DUE TO THE DRIER N-NE
FLOW. THUS...AFTER WHATEVER SNOW THE CASCADES GET LATE THIS WEEK...IT
WILL BE LOST OVER THE WEEKEND. THE GFS ALSO HAS A CHANGE TO COLDER
NW-N FLOW ALOFT BUT IT MAINTAINS AN OPEN TROUGH INSTEAD OF THE CLOSED
UPPER LOW ECMWF SOLUTION. WHILE STILL SOME SIGNIFICANT UNCERTAINTY
EXISTS WITH RESPECT TO THE TIMING OF THE COLD AIR AND JUST HOW COLD
THE AIR WILL BE...IT DOES APPEAR THAT A CHANGE TO MUCH COOLER
CONDITIONS WILL MOVE INTO THE REGION. SNOW LEVELS SHOULD BE QUITE LOW
OVER THE HOLIDAY...BUT DROPPED POPS SUBSTANTIALLY NEXT THU AND THU
NIGHT. WEISHAAR

&&

.AVIATION...LIGHT WINDS AND A MOIST LOWER ATMOSPHERE WILL CONTINUE
TO BRING A MIX OF IFR TO VFR CONDITIONS THROUGH LATE THURSDAY
MORNING. AS THE NEXT FRONT APPROACHES AND THE WINDS PICK UP AHEAD
OF IT EXPECT MOST TAF SITES TO IMPROVE TO VFR BY THURSDAY
AFTERNOON. THE FRONT WILL LIKELY PUSH INTO THE COAST AROUND 03Z
FRIDAY...AND INTO THE INTERIOR AROUND 06Z FRIDAY. EXPECT BRIEF
PERIODS OF IFR TO MVFR CIGS AND VIS UNDER LIGHT TO MODERATE RAIN
BANDS ASSOCIATED WITH THE FRONT.

KPDX AND APPROACHES...VFR CONDITIONS EXPECTED TO PERSIST THROUGH
FRIDAY MORNING. HOWEVER...BRIEF PERIODS OF MVFR CIGS ARE POSSIBLE
THROUGH LATE THURSDAY MORNING DUE TO A MOIST LOWER ATMOSPHERE. A
FRONT WILL PUSH THROUGH AFTER 06Z FRIDAY AND COULD BRING BRIEF
PERIODS TO IFR TO MVFR CIGS AND VIS UNDER LIGHT TO MODERATE RAIN
BANDS. /64

&&

.MARINE...SEAS CONTINUED TO HOVER AROUND 10 FT OVERNIGHT AND LOOKS
TO REMAIN ELEVATED THROUGHOUT THE MORNING SO THE SMALL CRAFT
ADVISORY FOR HAZARDOUS SEAS WAS EXTENDED TO 1 PM. A STRONG
FRONTAL SYSTEM IS STILL ON TRACK TO MOVE ACROSS THE WATERS TODAY
AND WILL BRING SOLID GALE GUSTS THROUGH THURSDAY NIGHT WITH SEAS
CLIMBING INTO THE MID TEENS. /64

PREVIOUS DISCUSSION FOLLOWS...EXPECT SEAS TO SUBSIDE FAIRLY
QUICKLY BACK DOWN INTO THE 10 TO 12 FT RANGE LATE THURSDAY NIGHT
INTO EARLY FRIDAY MORNING. HOWEVER...THESE LOWER WAVE HEIGHTS WILL
BE SHORT LIVED AS AN IMPRESSIVE LONG PERIOD WESTERLY SWELL WILL
LIKELY ARRIVE FRIDAY AFTERNOON INTO FRIDAY EVENING. WAVE HEIGHTS
MAY NEARLY DOUBLE IN A 6 HOUR PERIOD SO THIS COULD CERTAINLY CATCH
OFF GUARD ANY UNINFORMED MARINERS THAT VENTURE OUT FRIDAY MORNING.
CONFIDENCE IS RELATIVELY HIGH THAT THIS SWELL WILL LIKELY EXCEED
20 FT. IN FACT...THESE PATTERNS OFTEN PRODUCE HIGHER SEAS THAN
FORECASTED BY THE ENP WAVE MODEL. A HIGH SURF ADVISORY APPEARS
LIKELY. THE GOOD NEWS IS THAT THE LARGEST SWELL WILL LIKELY ARRIVE
DURING LOW TIDE AND DURING THE NIGHT TIME HOURS WHEN MOST MARINERS
AND BEACH GOERS ARE NOT IN HARMS WAY.

THIS SWELL TRAIN WILL SUBSIDE SATURDAY...BUT ANOTHER STRONG
FRONTAL STORM SYSTEM WILL LIKELY PRODUCE GALE FORCE TO POSSIBLY
LOW END STORM FORCE GUSTS ACROSS THE WATERS ON SATURDAY. THIS WILL
EFFECTIVELY KEEP SEAS FLIRTING WITH THE 20 FT MARK ON SATURDAY.

NORMAL HIGH TIDE AT TOKE POINT WASHINGTON IS SUPPOSED TO BE 10.3
FT SATURDAY AROUND 11 AM. WITH SOUTHERLY WINDS SUPPORTING A
POSITIVE TIDAL ANOMALY OF AROUND 0.5 FT...HIGH TIDE WILL APPROACH
11 FT AND MAY RESULT IN SOME MINOR TIDAL OVERFLOW FLOODING IN
WILLAPA BAY. GIVEN THE HEAVIER RAINS WILL NOT HAVE ARRIVED...THE
WILLAPA RIVER IS FORECASTED TO BE AROUND 20 PERCENT OF FLOOD
FLOW ON SATURDAY...WHICH SHOULD HELP MITIGATE MORE WIDESPREAD
COASTAL FLOODING CONCERNS.

HIGH PRESSURE WILL SLOWLY BUILD OVER THE NORTHEAST PACIFIC LATE IN
THE WEEKEND AND INTO EARLY NEXT WEEK...WHICH SHOULD RESULT IN
WINDS AND SEAS RELAXING QUITE A BIT WHEN COMPARED TO THE
FRIDAY/SATURDAY TIME FRAME. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.

WA...NONE.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 PM PST THIS AFTERNOON FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     GALE WARNING FROM 1 PM THIS AFTERNOON TO MIDNIGHT PST TONIGHT
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 PM PST THIS
     AFTERNOON FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
     FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 6 AM
     PST FRIDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 180536
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
934 PM PST WED DEC 17 2014

.SYNOPSIS...WEAK LOW PRESSURE CONTINUES TO BRING AREAS OF LIGHT RAIN
AND CASCADE SNOW TO THE DISTRICT THIS EVENING. EXPECT PRECIPITATION
TO BECOME MORE SPOTTY OVERNIGHT AS THE LOW DECAYS. LINGERING MOISTURE
SHOULD ALLOW PATCHY FOG TO DEVELOP OVERNIGHT. RAIN WILL REDEVELOP BY
LATE THURSDAY AND INCREASE OVERNIGHT AS A MORE ORGANIZED FRONTAL
SYSTEM MOVES ONSHORE. THIS FRONT WILL ALSO BRING A PERIOD OF WINDY
CONDITIONS TO THE COAST THURSDAY AFTERNOON AND EVENING. RAIN WILL
TAPER TO SHOWERS BEHIND THE COLD FRONT FRIDAY.SNOW LEVELS WILL RISE
ABOVE THE CASCADE PASSES AHEAD OF THIS FRONT...THEN FALL BACK BELOW
PASS LEVEL WITH SOME ACCUMULATING SNOW SHOWERS FRIDAY AND FRIDAY
NIGHT. MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND. THERE IS
POTENTIAL FOR AN ATMOSPHERIC RIVER AND ASSOCIATED HEAVY RAIN TO
DEVELOP OVER THE AREA...WITH SOME FLOODING POSSIBLE LATER THIS
WEEKEND INTO EARLY NEXT WEEK.

&&

.SHORT TERM...TONIGHT THROUGH SATURDAY...WEAK LOW PRESSURE CAN BE
SEEN ON NWS DOPPLER RADAR MOVING NORTHEASTWARD INTO SW WASHINGTON
THIS EVENING...WITH A VERY LOOSE CIRCULATION MOVING ACROSS THE
WILLAPA HILLS. THIS SYSTEM IS DECAYING...AND AS A RESULT THE AREAL
COVERAGE OF LIGHT RAIN AND CASCADE SNOW IS DECREASING THIS EVENING.
THAT SAID...THE AIR MASS REMAINS VERY MOIST AND FLOW REMAINS WEAKLY
CYCLONIC UP TO 700 MB. THEREFORE IT WOULD NOT BE SURPRISING TO SEE
AREAS OF -RA CONTINUE ACROSS OUR FORECAST AREA OVERNIGHT AND INTO
THURSDAY. ALSO...THE 00Z NAM/GFS KEY IN ON ANOTHER WEAK LOW OFF THE
SRN OREGON COAST WHICH IS BRINGING A BIT MORE LIGHT RAIN TO SW OREGON
THIS EVENING. THIS LOW IS EXPECTED TO LIFT N-NE AND DECAY WHILE
MOVING ACROSS OUR FORECAST AREA THURSDAY...BUT COULD HOLD TOGETHER
ENOUGH TO BRING SOME PERIODS OF LIGHT RAIN THROUGH THE DAY. KEEPING
THIS IN MIND...WE INCREASED POPS THROUGH THURSDAY...BUT QPF WILL BE
VERY LIGHT.

ATTENTION THEN TURNS TO THE NEXT MUCH STRONGER SYSTEM...PRESENTLY
PUSHING A COLD FRONT ACROSS 140W. THIS SYSTEM WILL BE A FAST
MOVER...LIKELY STARTING TO SPREAD MORE SIGNIFICANT RAIN ONSHORE BY
LATE THURSDAY AFTERNOON. 00Z NAM/GFS SUGGEST THE NORTH AND CENTRAL
OREGON COAST GET INTO THE WARM SECTOR AHEAD OF THE COLD FRONT...
OPENING THE DOOR FOR STRONGER WINDS TO SURFACE AT LEAST AT THE
BEACHES AND HEADLANDS THURSDAY AFTERNOON AND EVENING. GRADIENTS
APPEAR TO REMAIN EASTERLY ENOUGH TO KEEP THE STRONGEST WINDS OUT OF
THE COASTAL COMMUNITIES...BUT THE 00Z NAM AND 4KM UW WRFGFS HAVE BEEN
TRENDING STRONGER WITH THE COASTAL JET AHEAD OF THE FRONT. THE 00Z
NAM SHOWS 950 MB WINDS UP TO 60 KT WITHIN THE COASTAL JET. DECIDED
EARLIER IN THE SHIFT TO ISSUE A HIGH WIND WATCH FOR THE BEACHES AND
HEADLANDS BASED ON THE 00Z NAM DATA...AND WITH THE UW WRFGFS TRENDING
STRONGER WE FEEL EVEN MORE CONFIDENT ABOUT THAT DECISION. THIS WILL
MAINLY BE AN ISSUE FOR TRAVELERS ALONG EXPOSED AREAS OF COASTAL
ROUTES...WHILE MOST COASTAL COMMUNITIES WILL LIKELY JUST SEE A BRIEF
1-3 HR PERIOD OF 40-45 MPH GUSTS.

MADE VERY FEW CHANGES BEYOND THURSDAY NIGHT AS THE CURRENT FORECAST
LOOKS ON TRACK FOR A VERY WET AND OCCASIONALLY WINDY WEEKEND. 00Z NAM
AND GFS CERTAINLY HAVE NOT BACKED DOWN FROM THEIR EARLIER FORECASTS
FOCUSING AN ATMOSPHERIC RIVER SQUARELY ON SW WASHINGTON AND NW
OREGON...WITH FLOODING RAINS POSSIBLE. THE 00Z WRFGFS CONTINUES TO
PRODUCE VERY HEAVY QPF WITH UP TO 8-12 INCHES OF RAIN IN THE HIGHER
TERRAIN AND 2-4 INCHES IN THE WILLAMETTE VALLEY BY MONDAY...EVEN WITH
HEAVY RAIN SHADOWING. WILL NEED TO MONITOR THIS VERY CLOSELY OVER THE
NEXT FEW DAYS AS SIMILAR SITUATIONS HAVE PRODUCED FLOODING ON AREA
MAINSTEM RIVERS.  WEAGLE

.HYDROLOGY...WHILE RIVER FORECASTS OF CURRENT MODEL PRECIPITATION
INDICATE FLOODING IS POSSIBLE ON A RIVER OR TWO IN THE FORECAST AREA
SUNDAY INTO MONDAY...A LOOK AT THE MOST CORRELATED ANALOGS TO THE 96
HOUR GFS MODEL FORECAST SHED LIGHT ON FLOODING CHANCES ACROSS OUR
FORECAST AREA LATE IN THE WEEKEND AND EARLY NEXT WEEK. THE THREE
MOST CORRELATED ANALOG WEATHER PATTERNS TO THE CURRENT 96 HOUR GFS
MODEL FORECAST ARE LATE JANUARY 2003...EARLY JANUARY 1983 AND LATE
NOVEMBER 1999. ALL THREE OF THESE EVENTS PRODUCED ISOLATED TO
SCATTERED RIVER FLOODING WITHIN NORTHWEST OREGON AND/OR SOUTHWEST
WASHINGTON. WHILE THERE ARE CERTAINLY NOTABLE DIFFERENCES BETWEEN
THE CURRENT PATTERN AND EACH OF THESE HISTORICAL ANALOGS...SOME
CRITICAL WEATHER PARAMETERS APPEAR EVEN MORE FAVORABLE FOR PRODUCING
HEAVIER RAINS THAN THESE PAST EVENTS. THIS CERTAINLY HELPS BUILD
CONFIDENCE THERE WILL BE HYDROLOGICAL IMPACTS WITHIN OUR FORECAST
AREA OF RESPONSIBILITY SO LONG AS THE PATTERN HOLDS.
NONETHELESS...THERE IS STILL CONSIDERABLE UNCERTAINTY IN WHERE THE
HEAVIEST RAIN WILL SET UP...AND EXACTLY WHICH RIVERS WILL FLOOD AND
WHEN. PLEASE CONTINUE TO MONITOR THE FORECAST IF YOU LIVE NEAR ANY
RIVERS FED BY THE THE CASCADES OR COAST RANGE...AND PLEASE SEE
WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR FOR THE LATEST RIVER
FORECASTS. /NEUMAN

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...MODELS MAINTAIN A
FLATTENED RIDGE OVER THE EASTERN PACIFIC FOR THE WEEKEND THROUGH
EARLY NEXT WEEK. WITH A NEARLY ZONAL JET AND ABUNDANT
MOISTURE...EXPECT PLENTY OF RAINFALL TO CONTINUE THROUGH SUNDAY. ON
MONDAY AND TUESDAY...SOME WEAK RIDGING MOVES OVER THE REGION BUT
SHOWERS LIKELY CONTINUE IN THE MOIST ONSHORE FLOW. AN UPPER TROUGH
DROPS SOUTH OVER THE REGION BY MIDWEEK WITH SOME RATHER COLD AIR AND
ADDITIONAL PRECIPITATION IN STORE. WHILE STILL SOME SIGNIFICANT
UNCERTAINTY EXISTS WITH RESPECT TO THE TIMING OF THE PRECIP VS COLD
AIR AND JUST HOW COLD THE AIR IS...IT DOES APPEAR THAT A SIGNIFICANT
SURGE OF COLD AIR MAY MOVE INTO THE REGION AND THEREFORE...DECREASED
TEMPERATURES ACCORDINGLY FOR THE TUE/WED PERIODS ACROSS THE REGION.
IT DOES APPEAR THAT SNOW LEVELS WILL DROP BELOW PASS LEVELS AT
LEAST...AND PERHAPS DOWN INTO THE FOOTHILL ELEVATIONS LATER
WEDNESDAY INTO THURSDAY. GIVEN THE UNCERTAINTY...THOSE PLANNING
HOLIDAY TRAVEL DURING THIS PERIOD SHOULD MONITOR THE FORECAST.
CULLEN

&&

.AVIATION...A MOIST LOWER ATMOSPHERE...DECREASING WINDS AND
VARYING VFR CLOUD DECKS SCATTERED OVER THE FORECAST WILL RESULT IN
A MIX OF IFR TO VFR CONDITIONS ACROSS THE AREA OVERNIGHT. SUSPECT
SOME DETERIORATION AT MOST TAF SITES. AS THE NEXT COLD FRONT
APPROACHES THE AREA THURSDAY...EXPECT SOUTHEAST TO EAST WINDS TO
INCREASE AGAIN...AND CAUSE MOST SITES WITH FLIGHT RESTRICTIONS TO
TURN VFR. EXPECT A PERIOD OF HIGH END IFR TO MVFR AS THE COLD
FRONT PUSHES INTO THE COAST AROUND 03Z FRIDAY...AND LIKELY AFTER
06Z FRIDAY FOR INTERIOR TAF SITES.

KPDX AND APPROACHES...DUE TO AMPLE LOW LEVEL MOISTURE AND
DECREASING WINDS OVER THE NEXT FEW HOURS...SUSPECT SOME
DETERIORATION...BUT CONFIDENCE IN THE DETAILS IS LOW.
HOWEVER...INCREASING EAST WINDS THURSDAY MORNING SHOULD ALLOW
ANY FLIGHT RESTRICTIONS TO DISAPPEAR. THEREAFTER...EXPECT
PRIMARILY VFR CONDITIONS THROUGH 06Z FRIDAY AS EAST WINDS CONTINUE
AHEAD OF A MODEST COLD FRONT. /NEUMAN

&&

.MARINE...SEAS CONTINUE TO HOVER NEAR 10 FT SO A SMALL CRAFT FOR
HAZARDOUS SEAS WAS EXTENDED THROUGH 4 AM...ALTHOUGH SEAS SHOULD
DROP SOLIDLY BELOW THIS HEIGHT WELL BEFORE THIS TIME. A MORE
ORGANIZED FRONTAL STORM SYSTEM WILL CAUSE IN WINDS TO INCREASE
ACROSS THE WATERS ON THURSDAY...PARTICULARLY OVER THE OUTER
WATERS. EVENTUALLY...THE FRONT WILL PUSH INTO THE WATERS DURING
THE EVENING AND PRODUCE A 3 TO 6 HOUR PERIOD OF GALE FORCE WIND
GUSTS OF 40 TO 45 KT ACROSS THE WATERS. SEAS SHOULD RESPOND
ACCORDINGLY AND RISE INTO AT LEAST THE MID TEENS. EXPECT SEAS TO
SUBSIDE FAIRLY QUICKLY BACK DOWN INTO THE 10 TO 12 FT RANGE LATE
THURSDAY NIGHT INTO EARLY FRIDAY MORNING. HOWEVER...THESE LOWER
WAVE HEIGHTS WILL BE SHORT LIVED AS AN IMPRESSIVE LONG PERIOD
WESTERLY SWELL WILL LIKELY ARRIVE FRIDAY AFTERNOON INTO FRIDAY
EVENING. WAVE HEIGHTS MAY NEARLY DOUBLE IN A 6 HOUR PERIOD SO THIS
COULD CERTAINLY CATCH OFF GUARD ANY UNINFORMED MARINERS THAT
VENTURE OUT FRIDAY MORNING. CONFIDENCE IS RELATIVELY HIGH THAT THIS
SWELL WILL LIKELY EXCEED 20 FT. IN FACT...THESE PATTERNS OFTEN
PRODUCE HIGHER SEAS THAN FORECASTED BY THE ENP WAVE MODEL. A HIGH
SURF ADVISORY APPEARS LIKELY. THE GOOD NEWS IS THAT THE LARGEST
SWELL WILL LIKELY ARRIVE DURING LOW TIDE AND DURING THE NIGHT TIME
HOURS WHEN MOST MARINERS AND BEACH GOERS ARE NOT IN HARMS WAY.

THIS SWELL TRAIN WILL SUBSIDE SATURDAY...BUT ANOTHER STRONG
FRONTAL STORM SYSTEM WILL LIKELY PRODUCE GALE FORCE TO POSSIBLY
LOW END STORM FORCE GUSTS ACROSS THE WATERS ON SATURDAY. THIS WILL
EFFECTIVELY KEEP SEAS FLIRTING WITH THE 20 FT MARK ON SATURDAY.

NORMAL HIGH TIDE AT TOKE POINT WASHINGTON IS SUPPOSED TO BE 10.3
FT SATURDAY AROUND 11 AM. WITH SOUTHERLY WINDS SUPPORTING A
POSITIVE TIDAL ANOMALY OF AROUND 0.5 FT...HIGH TIDE WILL APPROACH
11 FT AND MAY RESULT IN SOME MINOR TIDAL OVERFLOW FLOODING IN
WILLAPA BAY. GIVEN THE HEAVIER RAINS WILL NOT HAVE ARRIVED...THE
WILLAPA RIVER IS FORECASTED TO BE AROUND 20 PERCENT OF FLOOD
FLOW ON SATURDAY...WHICH SHOULD HELP MITIGATE MORE WIDESPREAD
COASTAL FLOODING CONCERNS.

HIGH PRESSURE WILL SLOWLY BUILD OVER THE NORTHEAST PACIFIC LATE IN
THE WEEKEND AND INTO EARLY NEXT WEEK...WHICH SHOULD RESULT IN
WINDS AND SEAS RELAXING QUITE A BIT WHEN COMPARED TO THE
FRIDAY/SATURDAY TIME FRAME. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WATCH FROM THURSDAY AFTERNOON THROUGH THURSDAY
     EVENING FOR CENTRAL OREGON COAST-NORTH OREGON COAST.

WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 4 AM TO 1 PM PST THURSDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     GALE WARNING FROM 1 PM THURSDAY TO MIDNIGHT PST THURSDAY NIGHT
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 AM PST THURSDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 AM
     PST THURSDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 180536
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
934 PM PST WED DEC 17 2014

.SYNOPSIS...WEAK LOW PRESSURE CONTINUES TO BRING AREAS OF LIGHT RAIN
AND CASCADE SNOW TO THE DISTRICT THIS EVENING. EXPECT PRECIPITATION
TO BECOME MORE SPOTTY OVERNIGHT AS THE LOW DECAYS. LINGERING MOISTURE
SHOULD ALLOW PATCHY FOG TO DEVELOP OVERNIGHT. RAIN WILL REDEVELOP BY
LATE THURSDAY AND INCREASE OVERNIGHT AS A MORE ORGANIZED FRONTAL
SYSTEM MOVES ONSHORE. THIS FRONT WILL ALSO BRING A PERIOD OF WINDY
CONDITIONS TO THE COAST THURSDAY AFTERNOON AND EVENING. RAIN WILL
TAPER TO SHOWERS BEHIND THE COLD FRONT FRIDAY.SNOW LEVELS WILL RISE
ABOVE THE CASCADE PASSES AHEAD OF THIS FRONT...THEN FALL BACK BELOW
PASS LEVEL WITH SOME ACCUMULATING SNOW SHOWERS FRIDAY AND FRIDAY
NIGHT. MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND. THERE IS
POTENTIAL FOR AN ATMOSPHERIC RIVER AND ASSOCIATED HEAVY RAIN TO
DEVELOP OVER THE AREA...WITH SOME FLOODING POSSIBLE LATER THIS
WEEKEND INTO EARLY NEXT WEEK.

&&

.SHORT TERM...TONIGHT THROUGH SATURDAY...WEAK LOW PRESSURE CAN BE
SEEN ON NWS DOPPLER RADAR MOVING NORTHEASTWARD INTO SW WASHINGTON
THIS EVENING...WITH A VERY LOOSE CIRCULATION MOVING ACROSS THE
WILLAPA HILLS. THIS SYSTEM IS DECAYING...AND AS A RESULT THE AREAL
COVERAGE OF LIGHT RAIN AND CASCADE SNOW IS DECREASING THIS EVENING.
THAT SAID...THE AIR MASS REMAINS VERY MOIST AND FLOW REMAINS WEAKLY
CYCLONIC UP TO 700 MB. THEREFORE IT WOULD NOT BE SURPRISING TO SEE
AREAS OF -RA CONTINUE ACROSS OUR FORECAST AREA OVERNIGHT AND INTO
THURSDAY. ALSO...THE 00Z NAM/GFS KEY IN ON ANOTHER WEAK LOW OFF THE
SRN OREGON COAST WHICH IS BRINGING A BIT MORE LIGHT RAIN TO SW OREGON
THIS EVENING. THIS LOW IS EXPECTED TO LIFT N-NE AND DECAY WHILE
MOVING ACROSS OUR FORECAST AREA THURSDAY...BUT COULD HOLD TOGETHER
ENOUGH TO BRING SOME PERIODS OF LIGHT RAIN THROUGH THE DAY. KEEPING
THIS IN MIND...WE INCREASED POPS THROUGH THURSDAY...BUT QPF WILL BE
VERY LIGHT.

ATTENTION THEN TURNS TO THE NEXT MUCH STRONGER SYSTEM...PRESENTLY
PUSHING A COLD FRONT ACROSS 140W. THIS SYSTEM WILL BE A FAST
MOVER...LIKELY STARTING TO SPREAD MORE SIGNIFICANT RAIN ONSHORE BY
LATE THURSDAY AFTERNOON. 00Z NAM/GFS SUGGEST THE NORTH AND CENTRAL
OREGON COAST GET INTO THE WARM SECTOR AHEAD OF THE COLD FRONT...
OPENING THE DOOR FOR STRONGER WINDS TO SURFACE AT LEAST AT THE
BEACHES AND HEADLANDS THURSDAY AFTERNOON AND EVENING. GRADIENTS
APPEAR TO REMAIN EASTERLY ENOUGH TO KEEP THE STRONGEST WINDS OUT OF
THE COASTAL COMMUNITIES...BUT THE 00Z NAM AND 4KM UW WRFGFS HAVE BEEN
TRENDING STRONGER WITH THE COASTAL JET AHEAD OF THE FRONT. THE 00Z
NAM SHOWS 950 MB WINDS UP TO 60 KT WITHIN THE COASTAL JET. DECIDED
EARLIER IN THE SHIFT TO ISSUE A HIGH WIND WATCH FOR THE BEACHES AND
HEADLANDS BASED ON THE 00Z NAM DATA...AND WITH THE UW WRFGFS TRENDING
STRONGER WE FEEL EVEN MORE CONFIDENT ABOUT THAT DECISION. THIS WILL
MAINLY BE AN ISSUE FOR TRAVELERS ALONG EXPOSED AREAS OF COASTAL
ROUTES...WHILE MOST COASTAL COMMUNITIES WILL LIKELY JUST SEE A BRIEF
1-3 HR PERIOD OF 40-45 MPH GUSTS.

MADE VERY FEW CHANGES BEYOND THURSDAY NIGHT AS THE CURRENT FORECAST
LOOKS ON TRACK FOR A VERY WET AND OCCASIONALLY WINDY WEEKEND. 00Z NAM
AND GFS CERTAINLY HAVE NOT BACKED DOWN FROM THEIR EARLIER FORECASTS
FOCUSING AN ATMOSPHERIC RIVER SQUARELY ON SW WASHINGTON AND NW
OREGON...WITH FLOODING RAINS POSSIBLE. THE 00Z WRFGFS CONTINUES TO
PRODUCE VERY HEAVY QPF WITH UP TO 8-12 INCHES OF RAIN IN THE HIGHER
TERRAIN AND 2-4 INCHES IN THE WILLAMETTE VALLEY BY MONDAY...EVEN WITH
HEAVY RAIN SHADOWING. WILL NEED TO MONITOR THIS VERY CLOSELY OVER THE
NEXT FEW DAYS AS SIMILAR SITUATIONS HAVE PRODUCED FLOODING ON AREA
MAINSTEM RIVERS.  WEAGLE

.HYDROLOGY...WHILE RIVER FORECASTS OF CURRENT MODEL PRECIPITATION
INDICATE FLOODING IS POSSIBLE ON A RIVER OR TWO IN THE FORECAST AREA
SUNDAY INTO MONDAY...A LOOK AT THE MOST CORRELATED ANALOGS TO THE 96
HOUR GFS MODEL FORECAST SHED LIGHT ON FLOODING CHANCES ACROSS OUR
FORECAST AREA LATE IN THE WEEKEND AND EARLY NEXT WEEK. THE THREE
MOST CORRELATED ANALOG WEATHER PATTERNS TO THE CURRENT 96 HOUR GFS
MODEL FORECAST ARE LATE JANUARY 2003...EARLY JANUARY 1983 AND LATE
NOVEMBER 1999. ALL THREE OF THESE EVENTS PRODUCED ISOLATED TO
SCATTERED RIVER FLOODING WITHIN NORTHWEST OREGON AND/OR SOUTHWEST
WASHINGTON. WHILE THERE ARE CERTAINLY NOTABLE DIFFERENCES BETWEEN
THE CURRENT PATTERN AND EACH OF THESE HISTORICAL ANALOGS...SOME
CRITICAL WEATHER PARAMETERS APPEAR EVEN MORE FAVORABLE FOR PRODUCING
HEAVIER RAINS THAN THESE PAST EVENTS. THIS CERTAINLY HELPS BUILD
CONFIDENCE THERE WILL BE HYDROLOGICAL IMPACTS WITHIN OUR FORECAST
AREA OF RESPONSIBILITY SO LONG AS THE PATTERN HOLDS.
NONETHELESS...THERE IS STILL CONSIDERABLE UNCERTAINTY IN WHERE THE
HEAVIEST RAIN WILL SET UP...AND EXACTLY WHICH RIVERS WILL FLOOD AND
WHEN. PLEASE CONTINUE TO MONITOR THE FORECAST IF YOU LIVE NEAR ANY
RIVERS FED BY THE THE CASCADES OR COAST RANGE...AND PLEASE SEE
WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR FOR THE LATEST RIVER
FORECASTS. /NEUMAN

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...MODELS MAINTAIN A
FLATTENED RIDGE OVER THE EASTERN PACIFIC FOR THE WEEKEND THROUGH
EARLY NEXT WEEK. WITH A NEARLY ZONAL JET AND ABUNDANT
MOISTURE...EXPECT PLENTY OF RAINFALL TO CONTINUE THROUGH SUNDAY. ON
MONDAY AND TUESDAY...SOME WEAK RIDGING MOVES OVER THE REGION BUT
SHOWERS LIKELY CONTINUE IN THE MOIST ONSHORE FLOW. AN UPPER TROUGH
DROPS SOUTH OVER THE REGION BY MIDWEEK WITH SOME RATHER COLD AIR AND
ADDITIONAL PRECIPITATION IN STORE. WHILE STILL SOME SIGNIFICANT
UNCERTAINTY EXISTS WITH RESPECT TO THE TIMING OF THE PRECIP VS COLD
AIR AND JUST HOW COLD THE AIR IS...IT DOES APPEAR THAT A SIGNIFICANT
SURGE OF COLD AIR MAY MOVE INTO THE REGION AND THEREFORE...DECREASED
TEMPERATURES ACCORDINGLY FOR THE TUE/WED PERIODS ACROSS THE REGION.
IT DOES APPEAR THAT SNOW LEVELS WILL DROP BELOW PASS LEVELS AT
LEAST...AND PERHAPS DOWN INTO THE FOOTHILL ELEVATIONS LATER
WEDNESDAY INTO THURSDAY. GIVEN THE UNCERTAINTY...THOSE PLANNING
HOLIDAY TRAVEL DURING THIS PERIOD SHOULD MONITOR THE FORECAST.
CULLEN

&&

.AVIATION...A MOIST LOWER ATMOSPHERE...DECREASING WINDS AND
VARYING VFR CLOUD DECKS SCATTERED OVER THE FORECAST WILL RESULT IN
A MIX OF IFR TO VFR CONDITIONS ACROSS THE AREA OVERNIGHT. SUSPECT
SOME DETERIORATION AT MOST TAF SITES. AS THE NEXT COLD FRONT
APPROACHES THE AREA THURSDAY...EXPECT SOUTHEAST TO EAST WINDS TO
INCREASE AGAIN...AND CAUSE MOST SITES WITH FLIGHT RESTRICTIONS TO
TURN VFR. EXPECT A PERIOD OF HIGH END IFR TO MVFR AS THE COLD
FRONT PUSHES INTO THE COAST AROUND 03Z FRIDAY...AND LIKELY AFTER
06Z FRIDAY FOR INTERIOR TAF SITES.

KPDX AND APPROACHES...DUE TO AMPLE LOW LEVEL MOISTURE AND
DECREASING WINDS OVER THE NEXT FEW HOURS...SUSPECT SOME
DETERIORATION...BUT CONFIDENCE IN THE DETAILS IS LOW.
HOWEVER...INCREASING EAST WINDS THURSDAY MORNING SHOULD ALLOW
ANY FLIGHT RESTRICTIONS TO DISAPPEAR. THEREAFTER...EXPECT
PRIMARILY VFR CONDITIONS THROUGH 06Z FRIDAY AS EAST WINDS CONTINUE
AHEAD OF A MODEST COLD FRONT. /NEUMAN

&&

.MARINE...SEAS CONTINUE TO HOVER NEAR 10 FT SO A SMALL CRAFT FOR
HAZARDOUS SEAS WAS EXTENDED THROUGH 4 AM...ALTHOUGH SEAS SHOULD
DROP SOLIDLY BELOW THIS HEIGHT WELL BEFORE THIS TIME. A MORE
ORGANIZED FRONTAL STORM SYSTEM WILL CAUSE IN WINDS TO INCREASE
ACROSS THE WATERS ON THURSDAY...PARTICULARLY OVER THE OUTER
WATERS. EVENTUALLY...THE FRONT WILL PUSH INTO THE WATERS DURING
THE EVENING AND PRODUCE A 3 TO 6 HOUR PERIOD OF GALE FORCE WIND
GUSTS OF 40 TO 45 KT ACROSS THE WATERS. SEAS SHOULD RESPOND
ACCORDINGLY AND RISE INTO AT LEAST THE MID TEENS. EXPECT SEAS TO
SUBSIDE FAIRLY QUICKLY BACK DOWN INTO THE 10 TO 12 FT RANGE LATE
THURSDAY NIGHT INTO EARLY FRIDAY MORNING. HOWEVER...THESE LOWER
WAVE HEIGHTS WILL BE SHORT LIVED AS AN IMPRESSIVE LONG PERIOD
WESTERLY SWELL WILL LIKELY ARRIVE FRIDAY AFTERNOON INTO FRIDAY
EVENING. WAVE HEIGHTS MAY NEARLY DOUBLE IN A 6 HOUR PERIOD SO THIS
COULD CERTAINLY CATCH OFF GUARD ANY UNINFORMED MARINERS THAT
VENTURE OUT FRIDAY MORNING. CONFIDENCE IS RELATIVELY HIGH THAT THIS
SWELL WILL LIKELY EXCEED 20 FT. IN FACT...THESE PATTERNS OFTEN
PRODUCE HIGHER SEAS THAN FORECASTED BY THE ENP WAVE MODEL. A HIGH
SURF ADVISORY APPEARS LIKELY. THE GOOD NEWS IS THAT THE LARGEST
SWELL WILL LIKELY ARRIVE DURING LOW TIDE AND DURING THE NIGHT TIME
HOURS WHEN MOST MARINERS AND BEACH GOERS ARE NOT IN HARMS WAY.

THIS SWELL TRAIN WILL SUBSIDE SATURDAY...BUT ANOTHER STRONG
FRONTAL STORM SYSTEM WILL LIKELY PRODUCE GALE FORCE TO POSSIBLY
LOW END STORM FORCE GUSTS ACROSS THE WATERS ON SATURDAY. THIS WILL
EFFECTIVELY KEEP SEAS FLIRTING WITH THE 20 FT MARK ON SATURDAY.

NORMAL HIGH TIDE AT TOKE POINT WASHINGTON IS SUPPOSED TO BE 10.3
FT SATURDAY AROUND 11 AM. WITH SOUTHERLY WINDS SUPPORTING A
POSITIVE TIDAL ANOMALY OF AROUND 0.5 FT...HIGH TIDE WILL APPROACH
11 FT AND MAY RESULT IN SOME MINOR TIDAL OVERFLOW FLOODING IN
WILLAPA BAY. GIVEN THE HEAVIER RAINS WILL NOT HAVE ARRIVED...THE
WILLAPA RIVER IS FORECASTED TO BE AROUND 20 PERCENT OF FLOOD
FLOW ON SATURDAY...WHICH SHOULD HELP MITIGATE MORE WIDESPREAD
COASTAL FLOODING CONCERNS.

HIGH PRESSURE WILL SLOWLY BUILD OVER THE NORTHEAST PACIFIC LATE IN
THE WEEKEND AND INTO EARLY NEXT WEEK...WHICH SHOULD RESULT IN
WINDS AND SEAS RELAXING QUITE A BIT WHEN COMPARED TO THE
FRIDAY/SATURDAY TIME FRAME. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WATCH FROM THURSDAY AFTERNOON THROUGH THURSDAY
     EVENING FOR CENTRAL OREGON COAST-NORTH OREGON COAST.

WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 4 AM TO 1 PM PST THURSDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     GALE WARNING FROM 1 PM THURSDAY TO MIDNIGHT PST THURSDAY NIGHT
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 AM PST THURSDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 AM
     PST THURSDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.





000
FXUS66 KPQR 180536
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
934 PM PST WED DEC 17 2014

.SYNOPSIS...WEAK LOW PRESSURE CONTINUES TO BRING AREAS OF LIGHT RAIN
AND CASCADE SNOW TO THE DISTRICT THIS EVENING. EXPECT PRECIPITATION
TO BECOME MORE SPOTTY OVERNIGHT AS THE LOW DECAYS. LINGERING MOISTURE
SHOULD ALLOW PATCHY FOG TO DEVELOP OVERNIGHT. RAIN WILL REDEVELOP BY
LATE THURSDAY AND INCREASE OVERNIGHT AS A MORE ORGANIZED FRONTAL
SYSTEM MOVES ONSHORE. THIS FRONT WILL ALSO BRING A PERIOD OF WINDY
CONDITIONS TO THE COAST THURSDAY AFTERNOON AND EVENING. RAIN WILL
TAPER TO SHOWERS BEHIND THE COLD FRONT FRIDAY.SNOW LEVELS WILL RISE
ABOVE THE CASCADE PASSES AHEAD OF THIS FRONT...THEN FALL BACK BELOW
PASS LEVEL WITH SOME ACCUMULATING SNOW SHOWERS FRIDAY AND FRIDAY
NIGHT. MILD AND VERY WET WEATHER IS EXPECTED THIS WEEKEND. THERE IS
POTENTIAL FOR AN ATMOSPHERIC RIVER AND ASSOCIATED HEAVY RAIN TO
DEVELOP OVER THE AREA...WITH SOME FLOODING POSSIBLE LATER THIS
WEEKEND INTO EARLY NEXT WEEK.

&&

.SHORT TERM...TONIGHT THROUGH SATURDAY...WEAK LOW PRESSURE CAN BE
SEEN ON NWS DOPPLER RADAR MOVING NORTHEASTWARD INTO SW WASHINGTON
THIS EVENING...WITH A VERY LOOSE CIRCULATION MOVING ACROSS THE
WILLAPA HILLS. THIS SYSTEM IS DECAYING...AND AS A RESULT THE AREAL
COVERAGE OF LIGHT RAIN AND CASCADE SNOW IS DECREASING THIS EVENING.
THAT SAID...THE AIR MASS REMAINS VERY MOIST AND FLOW REMAINS WEAKLY
CYCLONIC UP TO 700 MB. THEREFORE IT WOULD NOT BE SURPRISING TO SEE
AREAS OF -RA CONTINUE ACROSS OUR FORECAST AREA OVERNIGHT AND INTO
THURSDAY. ALSO...THE 00Z NAM/GFS KEY IN ON ANOTHER WEAK LOW OFF THE
SRN OREGON COAST WHICH IS BRINGING A BIT MORE LIGHT RAIN TO SW OREGON
THIS EVENING. THIS LOW IS EXPECTED TO LIFT N-NE AND DECAY WHILE
MOVING ACROSS OUR FORECAST AREA THURSDAY...BUT COULD HOLD TOGETHER
ENOUGH TO BRING SOME PERIODS OF LIGHT RAIN THROUGH THE DAY. KEEPING
THIS IN MIND...WE INCREASED POPS THROUGH THURSDAY...BUT QPF WILL BE
VERY LIGHT.

ATTENTION THEN TURNS TO THE NEXT MUCH STRONGER SYSTEM...PRESENTLY
PUSHING A COLD FRONT ACROSS 140W. THIS SYSTEM WILL BE A FAST
MOVER...LIKELY STARTING TO SPREAD MORE SIGNIFICANT RAIN ONSHORE BY
LATE THURSDAY AFTERNOON. 00Z NAM/GFS SUGGEST THE NORTH AND CENTRAL
OREGON COAST GET INTO THE WARM SECTOR AHEAD OF THE COLD FRONT...
OPENING THE DOOR FOR STRONGER WINDS TO SURFACE AT LEAST AT THE
BEACHES AND HEADLANDS THURSDAY AFTERNOON AND EVENING. GRADIENTS
APPEAR TO REMAIN EASTERLY ENOUGH TO KEEP THE STRONGEST WINDS OUT OF
THE COASTAL COMMUNITIES...BUT THE 00Z NAM AND 4KM UW WRFGFS HAVE BEEN
TRENDING STRONGER WITH THE COASTAL JET AHEAD OF THE FRONT. THE 00Z
NAM SHOWS 950 MB WINDS UP TO 60 KT WITHIN THE COASTAL JET. DECIDED
EARLIER IN THE SHIFT TO ISSUE A HIGH WIND WATCH FOR THE BEACHES AND
HEADLANDS BASED ON THE 00Z NAM DATA...AND WITH THE UW WRFGFS TRENDING
STRONGER WE FEEL EVEN MORE CONFIDENT ABOUT THAT DECISION. THIS WILL
MAINLY BE AN ISSUE FOR TRAVELERS ALONG EXPOSED AREAS OF COASTAL
ROUTES...WHILE MOST COASTAL COMMUNITIES WILL LIKELY JUST SEE A BRIEF
1-3 HR PERIOD OF 40-45 MPH GUSTS.

MADE VERY FEW CHANGES BEYOND THURSDAY NIGHT AS THE CURRENT FORECAST
LOOKS ON TRACK FOR A VERY WET AND OCCASIONALLY WINDY WEEKEND. 00Z NAM
AND GFS CERTAINLY HAVE NOT BACKED DOWN FROM THEIR EARLIER FORECASTS
FOCUSING AN ATMOSPHERIC RIVER SQUARELY ON SW WASHINGTON AND NW
OREGON...WITH FLOODING RAINS POSSIBLE. THE 00Z WRFGFS CONTINUES TO
PRODUCE VERY HEAVY QPF WITH UP TO 8-12 INCHES OF RAIN IN THE HIGHER
TERRAIN AND 2-4 INCHES IN THE WILLAMETTE VALLEY BY MONDAY...EVEN WITH
HEAVY RAIN SHADOWING. WILL NEED TO MONITOR THIS VERY CLOSELY OVER THE
NEXT FEW DAYS AS SIMILAR SITUATIONS HAVE PRODUCED FLOODING ON AREA
MAINSTEM RIVERS.  WEAGLE

.HYDROLOGY...WHILE RIVER FORECASTS OF CURRENT MODEL PRECIPITATION
INDICATE FLOODING IS POSSIBLE ON A RIVER OR TWO IN THE FORECAST AREA
SUNDAY INTO MONDAY...A LOOK AT THE MOST CORRELATED ANALOGS TO THE 96
HOUR GFS MODEL FORECAST SHED LIGHT ON FLOODING CHANCES ACROSS OUR
FORECAST AREA LATE IN THE WEEKEND AND EARLY NEXT WEEK. THE THREE
MOST CORRELATED ANALOG WEATHER PATTERNS TO THE CURRENT 96 HOUR GFS
MODEL FORECAST ARE LATE JANUARY 2003...EARLY JANUARY 1983 AND LATE
NOVEMBER 1999. ALL THREE OF THESE EVENTS PRODUCED ISOLATED TO
SCATTERED RIVER FLOODING WITHIN NORTHWEST OREGON AND/OR SOUTHWEST
WASHINGTON. WHILE THERE ARE CERTAINLY NOTABLE DIFFERENCES BETWEEN
THE CURRENT PATTERN AND EACH OF THESE HISTORICAL ANALOGS...SOME
CRITICAL WEATHER PARAMETERS APPEAR EVEN MORE FAVORABLE FOR PRODUCING
HEAVIER RAINS THAN THESE PAST EVENTS. THIS CERTAINLY HELPS BUILD
CONFIDENCE THERE WILL BE HYDROLOGICAL IMPACTS WITHIN OUR FORECAST
AREA OF RESPONSIBILITY SO LONG AS THE PATTERN HOLDS.
NONETHELESS...THERE IS STILL CONSIDERABLE UNCERTAINTY IN WHERE THE
HEAVIEST RAIN WILL SET UP...AND EXACTLY WHICH RIVERS WILL FLOOD AND
WHEN. PLEASE CONTINUE TO MONITOR THE FORECAST IF YOU LIVE NEAR ANY
RIVERS FED BY THE THE CASCADES OR COAST RANGE...AND PLEASE SEE
WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR FOR THE LATEST RIVER
FORECASTS. /NEUMAN

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...MODELS MAINTAIN A
FLATTENED RIDGE OVER THE EASTERN PACIFIC FOR THE WEEKEND THROUGH
EARLY NEXT WEEK. WITH A NEARLY ZONAL JET AND ABUNDANT
MOISTURE...EXPECT PLENTY OF RAINFALL TO CONTINUE THROUGH SUNDAY. ON
MONDAY AND TUESDAY...SOME WEAK RIDGING MOVES OVER THE REGION BUT
SHOWERS LIKELY CONTINUE IN THE MOIST ONSHORE FLOW. AN UPPER TROUGH
DROPS SOUTH OVER THE REGION BY MIDWEEK WITH SOME RATHER COLD AIR AND
ADDITIONAL PRECIPITATION IN STORE. WHILE STILL SOME SIGNIFICANT
UNCERTAINTY EXISTS WITH RESPECT TO THE TIMING OF THE PRECIP VS COLD
AIR AND JUST HOW COLD THE AIR IS...IT DOES APPEAR THAT A SIGNIFICANT
SURGE OF COLD AIR MAY MOVE INTO THE REGION AND THEREFORE...DECREASED
TEMPERATURES ACCORDINGLY FOR THE TUE/WED PERIODS ACROSS THE REGION.
IT DOES APPEAR THAT SNOW LEVELS WILL DROP BELOW PASS LEVELS AT
LEAST...AND PERHAPS DOWN INTO THE FOOTHILL ELEVATIONS LATER
WEDNESDAY INTO THURSDAY. GIVEN THE UNCERTAINTY...THOSE PLANNING
HOLIDAY TRAVEL DURING THIS PERIOD SHOULD MONITOR THE FORECAST.
CULLEN

&&

.AVIATION...A MOIST LOWER ATMOSPHERE...DECREASING WINDS AND
VARYING VFR CLOUD DECKS SCATTERED OVER THE FORECAST WILL RESULT IN
A MIX OF IFR TO VFR CONDITIONS ACROSS THE AREA OVERNIGHT. SUSPECT
SOME DETERIORATION AT MOST TAF SITES. AS THE NEXT COLD FRONT
APPROACHES THE AREA THURSDAY...EXPECT SOUTHEAST TO EAST WINDS TO
INCREASE AGAIN...AND CAUSE MOST SITES WITH FLIGHT RESTRICTIONS TO
TURN VFR. EXPECT A PERIOD OF HIGH END IFR TO MVFR AS THE COLD
FRONT PUSHES INTO THE COAST AROUND 03Z FRIDAY...AND LIKELY AFTER
06Z FRIDAY FOR INTERIOR TAF SITES.

KPDX AND APPROACHES...DUE TO AMPLE LOW LEVEL MOISTURE AND
DECREASING WINDS OVER THE NEXT FEW HOURS...SUSPECT SOME
DETERIORATION...BUT CONFIDENCE IN THE DETAILS IS LOW.
HOWEVER...INCREASING EAST WINDS THURSDAY MORNING SHOULD ALLOW
ANY FLIGHT RESTRICTIONS TO DISAPPEAR. THEREAFTER...EXPECT
PRIMARILY VFR CONDITIONS THROUGH 06Z FRIDAY AS EAST WINDS CONTINUE
AHEAD OF A MODEST COLD FRONT. /NEUMAN

&&

.MARINE...SEAS CONTINUE TO HOVER NEAR 10 FT SO A SMALL CRAFT FOR
HAZARDOUS SEAS WAS EXTENDED THROUGH 4 AM...ALTHOUGH SEAS SHOULD
DROP SOLIDLY BELOW THIS HEIGHT WELL BEFORE THIS TIME. A MORE
ORGANIZED FRONTAL STORM SYSTEM WILL CAUSE IN WINDS TO INCREASE
ACROSS THE WATERS ON THURSDAY...PARTICULARLY OVER THE OUTER
WATERS. EVENTUALLY...THE FRONT WILL PUSH INTO THE WATERS DURING
THE EVENING AND PRODUCE A 3 TO 6 HOUR PERIOD OF GALE FORCE WIND
GUSTS OF 40 TO 45 KT ACROSS THE WATERS. SEAS SHOULD RESPOND
ACCORDINGLY AND RISE INTO AT LEAST THE MID TEENS. EXPECT SEAS TO
SUBSIDE FAIRLY QUICKLY BACK DOWN INTO THE 10 TO 12 FT RANGE LATE
THURSDAY NIGHT INTO EARLY FRIDAY MORNING. HOWEVER...THESE LOWER
WAVE HEIGHTS WILL BE SHORT LIVED AS AN IMPRESSIVE LONG PERIOD
WESTERLY SWELL WILL LIKELY ARRIVE FRIDAY AFTERNOON INTO FRIDAY
EVENING. WAVE HEIGHTS MAY NEARLY DOUBLE IN A 6 HOUR PERIOD SO THIS
COULD CERTAINLY CATCH OFF GUARD ANY UNINFORMED MARINERS THAT
VENTURE OUT FRIDAY MORNING. CONFIDENCE IS RELATIVELY HIGH THAT THIS
SWELL WILL LIKELY EXCEED 20 FT. IN FACT...THESE PATTERNS OFTEN
PRODUCE HIGHER SEAS THAN FORECASTED BY THE ENP WAVE MODEL. A HIGH
SURF ADVISORY APPEARS LIKELY. THE GOOD NEWS IS THAT THE LARGEST
SWELL WILL LIKELY ARRIVE DURING LOW TIDE AND DURING THE NIGHT TIME
HOURS WHEN MOST MARINERS AND BEACH GOERS ARE NOT IN HARMS WAY.

THIS SWELL TRAIN WILL SUBSIDE SATURDAY...BUT ANOTHER STRONG
FRONTAL STORM SYSTEM WILL LIKELY PRODUCE GALE FORCE TO POSSIBLY
LOW END STORM FORCE GUSTS ACROSS THE WATERS ON SATURDAY. THIS WILL
EFFECTIVELY KEEP SEAS FLIRTING WITH THE 20 FT MARK ON SATURDAY.

NORMAL HIGH TIDE AT TOKE POINT WASHINGTON IS SUPPOSED TO BE 10.3
FT SATURDAY AROUND 11 AM. WITH SOUTHERLY WINDS SUPPORTING A
POSITIVE TIDAL ANOMALY OF AROUND 0.5 FT...HIGH TIDE WILL APPROACH
11 FT AND MAY RESULT IN SOME MINOR TIDAL OVERFLOW FLOODING IN
WILLAPA BAY. GIVEN THE HEAVIER RAINS WILL NOT HAVE ARRIVED...THE
WILLAPA RIVER IS FORECASTED TO BE AROUND 20 PERCENT OF FLOOD
FLOW ON SATURDAY...WHICH SHOULD HELP MITIGATE MORE WIDESPREAD
COASTAL FLOODING CONCERNS.

HIGH PRESSURE WILL SLOWLY BUILD OVER THE NORTHEAST PACIFIC LATE IN
THE WEEKEND AND INTO EARLY NEXT WEEK...WHICH SHOULD RESULT IN
WINDS AND SEAS RELAXING QUITE A BIT WHEN COMPARED TO THE
FRIDAY/SATURDAY TIME FRAME. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WATCH FROM THURSDAY AFTERNOON THROUGH THURSDAY
     EVENING FOR CENTRAL OREGON COAST-NORTH OREGON COAST.

WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 4 AM TO 1 PM PST THURSDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     GALE WARNING FROM 1 PM THURSDAY TO MIDNIGHT PST THURSDAY NIGHT
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 AM PST THURSDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 AM
     PST THURSDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 172252
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
252 PM PST WED DEC 17 2014

.SYNOPSIS...WEAK LOW PRESSURE WILL CROSS THE AREA THIS EVENING WITH
SHOWERS LINGERING OVERNIGHT. EXPECT FAIRLY QUIET WEATHER TO START
THE DAY THURSDAY. A MORE ORGANIZED FRONT WILL BRING GUSTY WINDS TO
THE COAST WITH RAIN SPREADING INLAND THURSDAY NIGHT AND FRIDAY.
RISING SNOW LEVELS WILL LIMIT SNOW TO THE HIGHEST PEAKS. COLDER AIR
BEHIND THE FRONT WILL BRING ACCUMULATING SNOW SHOWERS FOR THE
CASCADES PASSES FRIDAY EVENING AND SATURDAY. MILD AND VERY WET
WEATHER ARRIVED THIS WEEKEND. THERE IS POTENTIAL FOR AN ATMOSPHERIC
RIVER AND ASSOCIATED HEAVY RAIN TO DEVELOP OVER THE AREA AFFECTING
RIVERS INTO NEXT WEEK.

&&

.SHORT TERM...TONIGHT THROUGH SATURDAY...A WEAK AND SPLITTING TROUGH
WILL SEND MOST OF ITS ENERGY SOUTH OF OUR AREA TONIGHT. WILL SEE
SHOWERS TAPER OFF OVERNIGHT AS HIGH PRESSURE BEGINS A TRANSIT ACROSS
THE AREA. WILL ALSO SEE CORRESPONDING SNOW LEVELS RISE ABOVE THE
PASSES AND GENERALLY LIMIT THE AMOUNT OF ACCUMULATIONS. THE RIDGE
AXIS QUICKLY PASSES EAST BY TOMORROW AFTERNOON LEADING TO A LARGELY
DRY DAY FOR THE INTERIOR.

ANOTHER MORE COHESIVE TROUGH AND FRONTAL SYSTEM WILL DIG OFFSHORE
WITH WARM FRONTAL RAIN TOUCHING THE COAST LATE FRIDAY AFTERNOON WITH
HEAVIER AMOUNTS BY EARLY FRIDAY EVENING. TIMING COULD BE EARLIER
DEPENDING ON MODEL OF CHOICE WITH THE GFS PERHAPS A COUPLE HOURS
FASTER THAN THE ECMWF AND THE NAM SLOWER YET. NAM TYPICALLY DOES NOT
HANDLE WARM PROCESS RAIN VERY WELL SO AM PUTTING LESS WEIGHT ON IT
TO START WITH. AS THE RAIN COMES IN...A COASTAL JET DEVELOPS
BRINGING FAIRLY GUSTY WINDS TO THE COAST AND COAST RANGE BUT NOTHING
TOO OUT OF THE ORDINARY. NOT ANTICIPATING ANY HIGHLIGHTS BUT
PROBABLY A RUN OF THE MILL WINDY COASTAL STORM. THE ASSOCIATED COLD
FRONT COME ASHORE AROUND 12Z FRIDAY MORNING AND CROSSES THE CASCADES
AROUND 17Z WITH COLDER AIR AND LOWERING SNOW LEVELS WITH AND MORE SO
BEHIND IT. PRECIPITATION TAPERS OFF AND BECOMES MORE SHOWERY IN
NATURE BEHIND THE FRONT. EXPECT LIGHT ACCUMULATING SNOW BEGINS AT
WILLAMETTE PASS AROUND DAY BREAK AND LOWERS TO NEAR GOVERNMENT PASS
LATER THAT MORNING. THE SNOW COMES TO BE TOO LITTLE...TOO LATE FOR
MUCH APPRECIABLE INCREASE IN THE SNOW PACK WITH PERHAPS A FEW INCHES
AT THE HIGHER PASSES AND LESS THAN AN INCH FOR GOVERNMENT CAMP.
HIGHER PEAKS COULD SEE UP TO A FOOT...HOWEVER. ANY OF THE MID
ELEVATION SNOW WILL BE RATHER SHORT-LIVED AS SNOW LEVELS IMMEDIATELY
BEGIN RISING IN ANTICIPATION OF THE PACIFIC STORM TRACK BECOMING
CENTERED OVER THE AREA.

MAIN ATTENTION THIS SHIFT HAS BEEN BE PLACED ON THE ATMOSPHERIC
RIVER EVENT SETTING UP TO AFFECT THE REGION THIS WEEKEND WITH
IMPACTS LASTING INTO NEXT WEEK. RAW GFS MODEL RUN ACCUMULATED QPF
AMOUNTS EXCEED 12 INCHES FOR PORTIONS OF THE CASCADES AND 10 INCHES
FOR THE COAST RANGE ENDING MONDAY MORNING. WILL SEE THE WARM RAINS
BEGIN AFFECTING THE COAST RANGE SATURDAY MORNING AND PUSH QUICKLY
INLAND TO THE CASCADES BY SATURDAY AFTERNOON. MOST OF THE HEAVY RAIN
OCCURS BEGINNING SATURDAY NIGHT. THERE WOULD BE DEEP WESTERLY FLOW
FROM THE SURFACE UP TO THE JET LEVEL THUS EXPECT THIS COULD BE AN
IDEAL OROGRAPHIC SITUATION TO EXTRACT A MAXIMUM AMOUNT OF RAIN FROM
WHATEVER COMES ASHORE. THERE IS GENERAL LARGE SCALE SUPPORT FROM THE
ECMWF ALBEIT WITH LESS QPF. PAST EXPERIENCE SHOWS FOLLOWING THE
HIGHER GFS QPF AMOUNTS IS STILL NOT ENOUGH AND THAT REALITY BRINGS
SIGNIFICANTLY MORE RAIN. ASSUMING THE CURRENT MODEL RUNS STAY
UNCHANGED IN THE FUTURE...WOULD EXPECT MULTIPLE MAINSTEM RIVERS
EXCEEDING FLOOD STAGE AS SOON AS SUNDAY EVENING.

HAVE ISSUED SOME OUTLOOK PRODUCTS TODAY LOOKING AHEAD TO FLOODING
POTENTIAL WITH THE CAVEAT THAT MODELS HAVE SHIFTED THE FOCUS FROM
NORTHERN WASHINGTON/BRITISH COLUMBIA SOUTH TO OUR AREA DURING THE
PAST 36 HOURS. ADDITIONAL SHIFTING IS EXPECTED AS WELL AS TIMING
DIFFERENCES. STAY TUNED AS THIS SITUATION EVOLVES OVER TIME.
/JBONK

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...MODELS MAINTAIN A
FLATTENED RIDGE OVER THE EASTERN PACIFIC FOR THE WEEKEND THROUGH
EARLY NEXT WEEK. WITH A NEARLY ZONAL JET AND ABUNDANT
MOISTURE...EXPECT PLENTY OF RAINFALL TO CONTINUE THROUGH SUNDAY. ON
MONDAY AND TUESDAY...SOME WEAK RIDGING MOVES OVER THE REGION BUT
SHOWERS LIKELY CONTINUE IN THE MOIST ONSHORE FLOW. AN UPPER TROUGH
DROPS SOUTH OVER THE REGION BY MIDWEEK WITH SOME RATHER COLD AIR AND
ADDITIONAL PRECIPITATION IN STORE. WHILE STILL SOME SIGNIFICANT
UNCERTAINTY EXISTS WITH RESPECT TO THE TIMING OF THE PRECIP VS COLD
AIR AND JUST HOW COLD THE AIR IS...IT DOES APPEAR THAT A SIGNIFICANT
SURGE OF COLD AIR MAY MOVE INTO THE REGION AND THEREFORE...DECREASED
TEMPERATURES ACCORDINGLY FOR THE TUE/WED PERIODS ACROSS THE REGION.
IT DOES APPEAR THAT SNOW LEVELS WILL DROP BELOW PASS LEVELS AT
LEAST...AND PERHAPS DOWN INTO THE FOOTHILL ELEVATIONS LATER
WEDNESDAY INTO THURSDAY. GIVEN THE UNCERTAINTY...THOSE PLANNING
HOLIDAY TRAVEL DURING THIS PERIOD SHOULD MONITOR THE FORECAST.
CULLEN

&&

.AVIATION...VFR CONDITIONS LIKELY TO CONTINUE THROUGH THIS
AFTERNOON. ONSHORE WINDS THIS EVENING BEHIND THE WEAK LOW MOVING
ONSHORE WILL ALLOW FOR CIGS AND VIS TO LOWER TO IFR TONIGHT WITH
THE DEVELOPMENT OF FOG/LOW STRATUS. THIS SHOULD HOLD ON THROUGH
THURSDAY MORNING...STARTING TO LIFT BACK TOWARD VFR AROUND 15 TO 18Z
THURSDAY AS WINDS START TO INCREASE OUT OF THE SOUTH. VFR WILL
CONTINUE THROUGH THURSDAY AFTERNOON...THOUGH LOW-LEVEL WIND SHEAR
WILL BE A CONCERN AT KTTD AND POSSIBLY KPDX AS 20 KT EASTERLY
WINDS FROM THE GORGE UNDERCUT INCREASING SOUTHERLY WINDS ALOFT.

KPDX AND APPROACHES...VFR CONDITIONS TO PERSIST THIS
EVENING. WEAK WINDS WILL COULD PROMOTE THE DEVELOPMENT OF FOG/LOW
STRATUS AFTER 06Z THURSDAY...DROPPING CIGS AND VIS TO IFR. THIS
SHOULD LIFT BACK TO VFR BY 18Z THURSDAY. -MCCOY

&&

.MARINE...WEAK LOW PRESSURE SYSTEM MOVING NORTHWARD ALONG THE
COAST HAS BROUGHT WINDS UP TO SCA CRITERIA THIS AFTERNOON IN OUR
SOUTHERN WATERS. THIS IS WEAKENING AND MOVING ONSHORE...WHICH
SHOULD ALLOW WINDS TO SUBSIDE FOR A BRIEF PERIOD THIS EVENING.
WINDS WILL BEGIN TO INCREASE ACROSS OUR WATERS THURSDAY MORNING
AHEAD OF A COLD FRONT WHICH WILL MOVE THROUGH OUR WATERS DURING
THE DAY THURSDAY. AHEAD OF THIS FRONT...WINDS LIKELY TO RAMP UP TO
GALE FORCE WITH A COASTAL JET FULLY DEVELOPED BY THURSDAY
EVENING AND PERSIST UNTIL THE FRONT MOVES ONSHORE EARLY FRIDAY
MORNING.

SEAS CURRENTLY AROUND 10-12 FT WILL DROP TO 9 FT LATER THIS
EVENING. SEAS WILL BEGIN TO BUILD AGAIN THURSDAY MORNING AS WINDS
INCREASE AHEAD OF THE COLD FRONT ON THURSDAY. SEAS EXPECTED TO
BUILD TO THE LOW-TO-MIDDLE TEENS THURSDAY EVENING...SUBSIDING TO
10 TO 12 FT EARLY FRIDAY MORNING. A DYNAMIC FETCH APPROACHES EARLY
FRIDAY...BRINGING A LARGE SWELL INTO OUR WATERS. THIS WILL CAUSE
SEAS TO RAPIDLY BUILD FRIDAY MORNING...REACHING 20 FT FRIDAY
EVENING. THE NEXT STRONG FRONT APPROACHES ON SATURDAY...WITH
GALES POSSIBLE...COULD BUILD SEAS ALREADY 15 TO 20 FEET...TO 20
TO 25 FT SATURDAY. -MCCOY

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 4 AM TO 1 PM PST THURSDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD OR OUT 60 NM.

     GALE WARNING FROM 1 PM THURSDAY TO MIDNIGHT PST THURSDAY NIGHT
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 9 PM PST THIS
     EVENING FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 PM PST THURSDAY FOR
     COASTAL WATERS FROM CASCADE HEAD OR TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 AM PST THURSDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 172252
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
252 PM PST WED DEC 17 2014

.SYNOPSIS...WEAK LOW PRESSURE WILL CROSS THE AREA THIS EVENING WITH
SHOWERS LINGERING OVERNIGHT. EXPECT FAIRLY QUIET WEATHER TO START
THE DAY THURSDAY. A MORE ORGANIZED FRONT WILL BRING GUSTY WINDS TO
THE COAST WITH RAIN SPREADING INLAND THURSDAY NIGHT AND FRIDAY.
RISING SNOW LEVELS WILL LIMIT SNOW TO THE HIGHEST PEAKS. COLDER AIR
BEHIND THE FRONT WILL BRING ACCUMULATING SNOW SHOWERS FOR THE
CASCADES PASSES FRIDAY EVENING AND SATURDAY. MILD AND VERY WET
WEATHER ARRIVED THIS WEEKEND. THERE IS POTENTIAL FOR AN ATMOSPHERIC
RIVER AND ASSOCIATED HEAVY RAIN TO DEVELOP OVER THE AREA AFFECTING
RIVERS INTO NEXT WEEK.

&&

.SHORT TERM...TONIGHT THROUGH SATURDAY...A WEAK AND SPLITTING TROUGH
WILL SEND MOST OF ITS ENERGY SOUTH OF OUR AREA TONIGHT. WILL SEE
SHOWERS TAPER OFF OVERNIGHT AS HIGH PRESSURE BEGINS A TRANSIT ACROSS
THE AREA. WILL ALSO SEE CORRESPONDING SNOW LEVELS RISE ABOVE THE
PASSES AND GENERALLY LIMIT THE AMOUNT OF ACCUMULATIONS. THE RIDGE
AXIS QUICKLY PASSES EAST BY TOMORROW AFTERNOON LEADING TO A LARGELY
DRY DAY FOR THE INTERIOR.

ANOTHER MORE COHESIVE TROUGH AND FRONTAL SYSTEM WILL DIG OFFSHORE
WITH WARM FRONTAL RAIN TOUCHING THE COAST LATE FRIDAY AFTERNOON WITH
HEAVIER AMOUNTS BY EARLY FRIDAY EVENING. TIMING COULD BE EARLIER
DEPENDING ON MODEL OF CHOICE WITH THE GFS PERHAPS A COUPLE HOURS
FASTER THAN THE ECMWF AND THE NAM SLOWER YET. NAM TYPICALLY DOES NOT
HANDLE WARM PROCESS RAIN VERY WELL SO AM PUTTING LESS WEIGHT ON IT
TO START WITH. AS THE RAIN COMES IN...A COASTAL JET DEVELOPS
BRINGING FAIRLY GUSTY WINDS TO THE COAST AND COAST RANGE BUT NOTHING
TOO OUT OF THE ORDINARY. NOT ANTICIPATING ANY HIGHLIGHTS BUT
PROBABLY A RUN OF THE MILL WINDY COASTAL STORM. THE ASSOCIATED COLD
FRONT COME ASHORE AROUND 12Z FRIDAY MORNING AND CROSSES THE CASCADES
AROUND 17Z WITH COLDER AIR AND LOWERING SNOW LEVELS WITH AND MORE SO
BEHIND IT. PRECIPITATION TAPERS OFF AND BECOMES MORE SHOWERY IN
NATURE BEHIND THE FRONT. EXPECT LIGHT ACCUMULATING SNOW BEGINS AT
WILLAMETTE PASS AROUND DAY BREAK AND LOWERS TO NEAR GOVERNMENT PASS
LATER THAT MORNING. THE SNOW COMES TO BE TOO LITTLE...TOO LATE FOR
MUCH APPRECIABLE INCREASE IN THE SNOW PACK WITH PERHAPS A FEW INCHES
AT THE HIGHER PASSES AND LESS THAN AN INCH FOR GOVERNMENT CAMP.
HIGHER PEAKS COULD SEE UP TO A FOOT...HOWEVER. ANY OF THE MID
ELEVATION SNOW WILL BE RATHER SHORT-LIVED AS SNOW LEVELS IMMEDIATELY
BEGIN RISING IN ANTICIPATION OF THE PACIFIC STORM TRACK BECOMING
CENTERED OVER THE AREA.

MAIN ATTENTION THIS SHIFT HAS BEEN BE PLACED ON THE ATMOSPHERIC
RIVER EVENT SETTING UP TO AFFECT THE REGION THIS WEEKEND WITH
IMPACTS LASTING INTO NEXT WEEK. RAW GFS MODEL RUN ACCUMULATED QPF
AMOUNTS EXCEED 12 INCHES FOR PORTIONS OF THE CASCADES AND 10 INCHES
FOR THE COAST RANGE ENDING MONDAY MORNING. WILL SEE THE WARM RAINS
BEGIN AFFECTING THE COAST RANGE SATURDAY MORNING AND PUSH QUICKLY
INLAND TO THE CASCADES BY SATURDAY AFTERNOON. MOST OF THE HEAVY RAIN
OCCURS BEGINNING SATURDAY NIGHT. THERE WOULD BE DEEP WESTERLY FLOW
FROM THE SURFACE UP TO THE JET LEVEL THUS EXPECT THIS COULD BE AN
IDEAL OROGRAPHIC SITUATION TO EXTRACT A MAXIMUM AMOUNT OF RAIN FROM
WHATEVER COMES ASHORE. THERE IS GENERAL LARGE SCALE SUPPORT FROM THE
ECMWF ALBEIT WITH LESS QPF. PAST EXPERIENCE SHOWS FOLLOWING THE
HIGHER GFS QPF AMOUNTS IS STILL NOT ENOUGH AND THAT REALITY BRINGS
SIGNIFICANTLY MORE RAIN. ASSUMING THE CURRENT MODEL RUNS STAY
UNCHANGED IN THE FUTURE...WOULD EXPECT MULTIPLE MAINSTEM RIVERS
EXCEEDING FLOOD STAGE AS SOON AS SUNDAY EVENING.

HAVE ISSUED SOME OUTLOOK PRODUCTS TODAY LOOKING AHEAD TO FLOODING
POTENTIAL WITH THE CAVEAT THAT MODELS HAVE SHIFTED THE FOCUS FROM
NORTHERN WASHINGTON/BRITISH COLUMBIA SOUTH TO OUR AREA DURING THE
PAST 36 HOURS. ADDITIONAL SHIFTING IS EXPECTED AS WELL AS TIMING
DIFFERENCES. STAY TUNED AS THIS SITUATION EVOLVES OVER TIME.
/JBONK

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...MODELS MAINTAIN A
FLATTENED RIDGE OVER THE EASTERN PACIFIC FOR THE WEEKEND THROUGH
EARLY NEXT WEEK. WITH A NEARLY ZONAL JET AND ABUNDANT
MOISTURE...EXPECT PLENTY OF RAINFALL TO CONTINUE THROUGH SUNDAY. ON
MONDAY AND TUESDAY...SOME WEAK RIDGING MOVES OVER THE REGION BUT
SHOWERS LIKELY CONTINUE IN THE MOIST ONSHORE FLOW. AN UPPER TROUGH
DROPS SOUTH OVER THE REGION BY MIDWEEK WITH SOME RATHER COLD AIR AND
ADDITIONAL PRECIPITATION IN STORE. WHILE STILL SOME SIGNIFICANT
UNCERTAINTY EXISTS WITH RESPECT TO THE TIMING OF THE PRECIP VS COLD
AIR AND JUST HOW COLD THE AIR IS...IT DOES APPEAR THAT A SIGNIFICANT
SURGE OF COLD AIR MAY MOVE INTO THE REGION AND THEREFORE...DECREASED
TEMPERATURES ACCORDINGLY FOR THE TUE/WED PERIODS ACROSS THE REGION.
IT DOES APPEAR THAT SNOW LEVELS WILL DROP BELOW PASS LEVELS AT
LEAST...AND PERHAPS DOWN INTO THE FOOTHILL ELEVATIONS LATER
WEDNESDAY INTO THURSDAY. GIVEN THE UNCERTAINTY...THOSE PLANNING
HOLIDAY TRAVEL DURING THIS PERIOD SHOULD MONITOR THE FORECAST.
CULLEN

&&

.AVIATION...VFR CONDITIONS LIKELY TO CONTINUE THROUGH THIS
AFTERNOON. ONSHORE WINDS THIS EVENING BEHIND THE WEAK LOW MOVING
ONSHORE WILL ALLOW FOR CIGS AND VIS TO LOWER TO IFR TONIGHT WITH
THE DEVELOPMENT OF FOG/LOW STRATUS. THIS SHOULD HOLD ON THROUGH
THURSDAY MORNING...STARTING TO LIFT BACK TOWARD VFR AROUND 15 TO 18Z
THURSDAY AS WINDS START TO INCREASE OUT OF THE SOUTH. VFR WILL
CONTINUE THROUGH THURSDAY AFTERNOON...THOUGH LOW-LEVEL WIND SHEAR
WILL BE A CONCERN AT KTTD AND POSSIBLY KPDX AS 20 KT EASTERLY
WINDS FROM THE GORGE UNDERCUT INCREASING SOUTHERLY WINDS ALOFT.

KPDX AND APPROACHES...VFR CONDITIONS TO PERSIST THIS
EVENING. WEAK WINDS WILL COULD PROMOTE THE DEVELOPMENT OF FOG/LOW
STRATUS AFTER 06Z THURSDAY...DROPPING CIGS AND VIS TO IFR. THIS
SHOULD LIFT BACK TO VFR BY 18Z THURSDAY. -MCCOY

&&

.MARINE...WEAK LOW PRESSURE SYSTEM MOVING NORTHWARD ALONG THE
COAST HAS BROUGHT WINDS UP TO SCA CRITERIA THIS AFTERNOON IN OUR
SOUTHERN WATERS. THIS IS WEAKENING AND MOVING ONSHORE...WHICH
SHOULD ALLOW WINDS TO SUBSIDE FOR A BRIEF PERIOD THIS EVENING.
WINDS WILL BEGIN TO INCREASE ACROSS OUR WATERS THURSDAY MORNING
AHEAD OF A COLD FRONT WHICH WILL MOVE THROUGH OUR WATERS DURING
THE DAY THURSDAY. AHEAD OF THIS FRONT...WINDS LIKELY TO RAMP UP TO
GALE FORCE WITH A COASTAL JET FULLY DEVELOPED BY THURSDAY
EVENING AND PERSIST UNTIL THE FRONT MOVES ONSHORE EARLY FRIDAY
MORNING.

SEAS CURRENTLY AROUND 10-12 FT WILL DROP TO 9 FT LATER THIS
EVENING. SEAS WILL BEGIN TO BUILD AGAIN THURSDAY MORNING AS WINDS
INCREASE AHEAD OF THE COLD FRONT ON THURSDAY. SEAS EXPECTED TO
BUILD TO THE LOW-TO-MIDDLE TEENS THURSDAY EVENING...SUBSIDING TO
10 TO 12 FT EARLY FRIDAY MORNING. A DYNAMIC FETCH APPROACHES EARLY
FRIDAY...BRINGING A LARGE SWELL INTO OUR WATERS. THIS WILL CAUSE
SEAS TO RAPIDLY BUILD FRIDAY MORNING...REACHING 20 FT FRIDAY
EVENING. THE NEXT STRONG FRONT APPROACHES ON SATURDAY...WITH
GALES POSSIBLE...COULD BUILD SEAS ALREADY 15 TO 20 FEET...TO 20
TO 25 FT SATURDAY. -MCCOY

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 4 AM TO 1 PM PST THURSDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD OR OUT 60 NM.

     GALE WARNING FROM 1 PM THURSDAY TO MIDNIGHT PST THURSDAY NIGHT
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 9 PM PST THIS
     EVENING FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 PM PST THURSDAY FOR
     COASTAL WATERS FROM CASCADE HEAD OR TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 AM PST THURSDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.





000
FXUS66 KPQR 171756
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
954 AM PST WED DEC 17 2014

.SYNOPSIS...A CLOSED LOW JUST OFFSHORE WEST OF THE OR/CA BORDER WILL
SLOWLY WEAKEN AND EVENTUALLY MOVE ONSHORE ALONG THE N OR/S WA COAST
THIS AFTERNOON. THIS WILL MAINTAIN LIGHT SHOWER ACTIVITY...MAINLY
OVER THE HIGHER TERRAIN THIS MORNING. AN UPPER LEVEL SHORTWAVE WILL
PUSH ONSHORE LATER TODAY...LIKELY BRINGING A PERIOD OF STEADIER
RAINFALL THROUGH EARLY THU MORNING. EXPECT A FAIRLY QUIET PERIOD FOR
MUCH OF THE DAY THU...BUT THEN A MORE ORGANIZED FRONT WILL BRING
GUSTY WINDS AND LARGE SURF TO THE COAST AND RAIN SPREADING INLAND
THURSDAY NIGHT AND FRIDAY. RISING SNOW LEVELS WILL LIMIT SNOW TO THE
HIGHEST PEAKS...BUT COLDER AIR BEHIND THE FRONT MAY RESULT IN SOME
SNOW SHOWERS FOR THE CASCADES PASSES FRIDAY EVENING AND SATURDAY.
WARMER AND MOISTER WEATHER IS EXPECTED THIS WEEKEND. THERE IS THE
POTENTIAL FOR AN ATMOSPHERIC RIVER TYPE SET UP AND ASSOCIATED HEAVY
RAIN TO DEVELOP OVER THE WEEKEND INTO EARLY NEXT WEEK.

&&

.UPDATE...SUBTLE CHANGES FOR TODAY MAINLY BY INCREASING POPS FOR THE
AFTERNOON...AND LATE AFTERNOON PROBABLY IN REALITY. ALSO PLAN ON
RAMPING UP COAST RANGE AND CASCADE WINDS FOR THE NEXT FRONTAL SYSTEM
MAINLY LATE THURSDAY AFTERNOON AND THURSDAY NIGHT. NOT ANTICIPATING
ANY HIGHLIGHTS BUT PROBABLY A RUN OF THE MILL WINDY COASTAL STORM.

MAIN ATTENTION WILL BE PLACED ON THE ATMOSPHERIC RIVER EVENT SETTING
UP TO AFFECT THE REGION THIS WEEKEND WITH IMPACTS LASTING INTO NEXT
WEEK. RAW GFS MODEL RUN ACCUMULATED QPF AMOUNTS EXCEED 12 INCHES FOR
PORTIONS OF THE CASCADES AND 10 INCHES FOR THE COAST RANGE ENDING
MONDAY MORNING. MOST OF THAT OCCURS BEGINNING SATURDAY. THERE WOULD
BE DEEP WESTERLY FLOW FROM THE SURFACE UP TO THE JET LEVEL THUS
EXPECT THIS COULD BE AN IDEAL SITUATION TO EXTRACT A MAXIMUM AMOUNT
OF RAIN FROM WHATEVER COMES ASHORE. THERE IS GENERAL LARGE SCALE
SUPPORT FROM THE ECMWF ALBEIT WITH LESS QPF. PAST EXPERIENCE SHOWS
FOLLOWING THE HIGHER GFS QPF AMOUNTS IS STILL NOT ENOUGH AND THAT
REALITY BRINGS SIGNIFICANTLY MORE RAIN. ASSUMING THE CURRENT MODEL
RUNS STAY UNCHANGED IN THE FUTURE...WOULD EXPECT MULTIPLE MAINSTEM
RIVERS EXCEEDING FLOOD STAGE AS SOON AS SUNDAY MORNING.

WILL BEGIN TO ISSUE SOME OUTLOOK PRODUCTS TODAY WITH THE CAVEAT THAT
MODELS HAVE RELATIVELY RECENTLY SHIFTED THE FOCUS FROM NORTHERN
WASHINGTON/BRITISH COLUMBIA SOUTH TO OUR AREA. ADDITIONAL SHIFTING
IS EXPECTED AS WELL AS TIMING DIFFERENCES. STAY TUNED AS THIS
SITUATION EVOLVES OVER TIME. /JBONK

&&

.PREV DISC... /ISSUED 259 AM PST WED DEC 17 2014/

SHORT TERM...TODAY THROUGH SATURDAY...VERY LIGHT RAIN CONTINUES TO
IMPACT SW WASHINGTON THIS MORNING BUT HAS OTHERWISE STARTED TO
DISSIPATE OVER THE SOUTHERN PORTION OF THE FORECAST AREA. WATER
VAPOR IMAGERY SHOWS A CLOSED LOW WEAKENING AS IT HAS PUSHED ONSHORE
NEAR THE OREGON/CALIFORNIA BORDER...WHILE AN UPPER LEVEL SHORTWAVE
IS ELONGATING AS IT APPROACHES THE PACIFIC NORTHWEST COASTLINE. NOT
MUCH CHANGE IN THE KTTD-KDLS GRADIENT...WHICH REMAINS AROUND -5
EARLY THIS MORNING. EAST WINDS CONTINUE TO GUST NEAR 25 MPH THROUGH
THE GORGE...BUT EXPECT THE EASTERLY GRADIENT TO WEAKEN BY LATE
TONIGHT.

AFTER A PERIOD OF LIGHT RAIN THIS MORNING...MODELS REMAIN CONSISTENT
IN SHOWING AN UPTICK IN PRECIP BY THIS AFTERNOON ASSOCIATED WITH THE
VORT MAX JUST OFFSHORE AROUND 45N 134W. THE LOWER LEVEL MOISTURE
ASSOCIATED WITH THE SURFACE LOW COMBINED WITH THE UPPER LEVEL FORCING
FROM THE SHORTWAVE SHOULD DRIVE A PERIOD OF STEADIER PRECIP THIS
EVENING AND THROUGH TONIGHT. THE VORT MAX PUSHES EAST OF THE CASCADES
BY 12Z THU...AFTER WHICH SHOWER ACTIVITY SHOULD DROP OFF
SIGNIFICANTLY.

WITH CLEARING SKIES AND LIGHT WINDS...SHOULD SEE SOME SHALLOW FOG TO
DEVELOP IN INTERIOR VALLEYS TONIGHT THROUGH EARLY THU MORNING. MODELS
MAINTAIN A THREAT FOR LIGHT PRECIP OVER THE HIGHER TERRAIN MUCH OF
THU...BUT OTHERWISE EXPECT DRY CONDITIONS TO PERSIST TO LOWER
ELEVATIONS. THE NEXT SIGNIFICANT FRONTAL SYSTEM ARRIVES LATE
THU...SPREADING RAIN AND BRINGING GUSTY COASTAL WINDS TO THE REGION
THROUGH FRI. PRECIPITABLE WATER IS EXPECTED TO BE NEAR AN INCH AND AN
APPROACHING JET STREAK SHOULD PROVIDE GOOD LIFT AND EXPECT THE
HIGHEST RAINFALL TOTALS OF 0.75 TO 1 INCH ACROSS THE COAST AND COAST
RANGE THROUGH MIDDAY FRI. OTHER LOCATIONS WILL SEE ON AVERAGE 0.5
INCHES OF RAIN. SNOW LEVELS SHOULD REMAIN ABOVE 5000 FEET DURING THE
PEAK RAIN PERIOD...BUT LOWER TO NEAR OR BELOW THE CASCADE PASSES
BEHIND THE FRONT FRIDAY AFTERNOON.

STRONG LOW PRESSURE OVER THE GULF OF ALASKA WILL PUSH INLAND LATE FRI
INTO EARLY SAT MORNING...SIMULTANEOUSLY FLATTENING A BROAD AREA OF
HIGH PRESSURE OVER THE EASTERN PACIFIC. THERE IS INCREASING
CONFIDENCE AN ATMOSPHERIC RIVER SCENARIO WILL SET UP...WITH ABUNDANT
MOISTURE AIMED DIRECTLY AT THE PACIFIC NORTHWEST SAT.

LONG TERM...SATURDAY NIGHT THROUGH TUESDAY...AS THIS TROUGH MOVES ON
SHORE SATURDAY...THE ASSOCIATED COLD FRONT MOVES ONSHORE AND STALLS
EAST-TO-WEST ACROSS NORTHWEST OREGON AND SOUTHWEST WASHINGTON. THIS
PUTS OUR AREA IN THE PATH OF RAIN STARTING SATURDAY THROUGH MONDAY.
SOME UNCERTAINTY EXISTS IN WHERE THIS BOUNDARY WILL SET UP...WHICH
WILL DETERMINE HOW MUCH RAINFALL WE WILL GET. ON TUESDAY...GEFS
ENSEMBLE SPAGHETTI PLOTS GET MESSY AND SIGNIFICANT DIFFERENCES START
TO SHOW UP BETWEEN THE GFS AND ECMWF...DECREASING CONFIDENCE ON HOW
THE REST OF THE WEEK WILL SHAPE UP.  AS OF NOW...THE MOST COMMON
SOLUTION IS THAT HIGH PRESSURE RIDGING WILL START TO BUILD BACK OVER
THE WESTERN U.S. WHICH SUGGESTS DRIER WEATHER STARTING TUESDAY...
THOUGH UNCERTAINTY IS VERY HIGH. -MCCOY

&&

.AVIATION...VFR CONDITIONS TO PERSIST AT MOST TAF SITES THROUGH
THIS AFTERNOON. AS SHOWERS MOVE IN...THERE MAY BE PERIODS OF
MVFR...ESPECIALLY AT SOUTH WILLAMETTE VALLEY SITES. CLEARING IS
POSSIBLE THIS EVENING...ALLOWING FOG TO DEVELOP IFR CIGS AND
VIS...BUT UNCERTAINTY IS HIGH BECAUSE THE MODELS ARE HINTING AT A
WEAK LOW PRESSURE SYSTEM OFF THE SOUTH OREGON COAST MOVING INLAND
THIS EVENING. THIS COULD BRING ADDITIONAL SHOWERS AND WINDS WHICH
WOULD KEEP CIGS VFR/MVFR. IF ANY CLEARING DOES OCCUR...EXPECT CIGS
AND VIS TO DROP TO IFR WITH THE DEVELOPMENT OF FOG/LOW STRATUS.

KPDX AND APPROACHES...VFR CONDITIONS TO PERSIST WEDNESDAY.
RAIN MAY BRING PERIODS OF MVFR CIGS AND VIS. CIGS COULD DROP TO
IFR TONIGHT WITH THE DEVELOPMENT OF FOG/LOW STRATUS AFTER 09Z
THURSDAY. -MCCOY

&&

.MARINE...WEST SWELL AROUND 10 FT BRINGING SEAS UP TO SMALL CRAFT
CRITERIA TODAY. SEAS DROP BELOW 10 FT LATER THIS EVENING. THE
SYSTEM OF INTEREST WILL BE TOMORROW WHICH WILL LIKELY BRING
SOUTHERLY GALES THROUGH EARLY FRIDAY. THERE IS STILL SOME
UNCERTAINTY ON TIMING...BUT MODELS ARE COMING INTO AGREEMENT THAT
WINDS WILL START TO INCREASE EARLY THURSDAY MORNING...REACHING
GALE FORCE BY EARLY AFTERNOON. SEAS BUILD INTO THE TEENS THURSDAY
AFTERNOON. SEAS DROP BACK DOWN TO 10 TO 12 FT ON FRIDAY AHEAD OF
THE NEXT SYSTEM WHICH WILL BRING SEAS UP EVEN HIGHER ON SATURDAY.

THERE IS STILL UNCERTAINTY ON THE TIMING OF THE SATURDAY SYSTEM...BUT
AS OF NOW MODELS ARE SUGGESTING THAT WINDS COULD AGAIN REACH GALE
FORCE EARLY SATURDAY...WHICH COULD BUILD SEAS INTO THE LOW 20S.
SEAS START TO FALL EARLY SUNDAY...DROPPING BACK INTO THE LOW
TEENS BY LATE SUNDAY OR EARLY MONDAY. AN ACTIVE WEATHER PATTERN
WILL CONTINUE THROUGH THIS WEEKEND...KEEPING SEAS ELEVATED
THROUGH EARLY NEXT WEEK WITH PERIODS OF GALES POSSIBLE. -MCCOY


&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...GALE WATCH FROM THURSDAY MORNING THROUGH THURSDAY EVENING FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 9 PM PST THIS
     EVENING FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST THIS AFTERNOON.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.





000
FXUS66 KPQR 171756
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
954 AM PST WED DEC 17 2014

.SYNOPSIS...A CLOSED LOW JUST OFFSHORE WEST OF THE OR/CA BORDER WILL
SLOWLY WEAKEN AND EVENTUALLY MOVE ONSHORE ALONG THE N OR/S WA COAST
THIS AFTERNOON. THIS WILL MAINTAIN LIGHT SHOWER ACTIVITY...MAINLY
OVER THE HIGHER TERRAIN THIS MORNING. AN UPPER LEVEL SHORTWAVE WILL
PUSH ONSHORE LATER TODAY...LIKELY BRINGING A PERIOD OF STEADIER
RAINFALL THROUGH EARLY THU MORNING. EXPECT A FAIRLY QUIET PERIOD FOR
MUCH OF THE DAY THU...BUT THEN A MORE ORGANIZED FRONT WILL BRING
GUSTY WINDS AND LARGE SURF TO THE COAST AND RAIN SPREADING INLAND
THURSDAY NIGHT AND FRIDAY. RISING SNOW LEVELS WILL LIMIT SNOW TO THE
HIGHEST PEAKS...BUT COLDER AIR BEHIND THE FRONT MAY RESULT IN SOME
SNOW SHOWERS FOR THE CASCADES PASSES FRIDAY EVENING AND SATURDAY.
WARMER AND MOISTER WEATHER IS EXPECTED THIS WEEKEND. THERE IS THE
POTENTIAL FOR AN ATMOSPHERIC RIVER TYPE SET UP AND ASSOCIATED HEAVY
RAIN TO DEVELOP OVER THE WEEKEND INTO EARLY NEXT WEEK.

&&

.UPDATE...SUBTLE CHANGES FOR TODAY MAINLY BY INCREASING POPS FOR THE
AFTERNOON...AND LATE AFTERNOON PROBABLY IN REALITY. ALSO PLAN ON
RAMPING UP COAST RANGE AND CASCADE WINDS FOR THE NEXT FRONTAL SYSTEM
MAINLY LATE THURSDAY AFTERNOON AND THURSDAY NIGHT. NOT ANTICIPATING
ANY HIGHLIGHTS BUT PROBABLY A RUN OF THE MILL WINDY COASTAL STORM.

MAIN ATTENTION WILL BE PLACED ON THE ATMOSPHERIC RIVER EVENT SETTING
UP TO AFFECT THE REGION THIS WEEKEND WITH IMPACTS LASTING INTO NEXT
WEEK. RAW GFS MODEL RUN ACCUMULATED QPF AMOUNTS EXCEED 12 INCHES FOR
PORTIONS OF THE CASCADES AND 10 INCHES FOR THE COAST RANGE ENDING
MONDAY MORNING. MOST OF THAT OCCURS BEGINNING SATURDAY. THERE WOULD
BE DEEP WESTERLY FLOW FROM THE SURFACE UP TO THE JET LEVEL THUS
EXPECT THIS COULD BE AN IDEAL SITUATION TO EXTRACT A MAXIMUM AMOUNT
OF RAIN FROM WHATEVER COMES ASHORE. THERE IS GENERAL LARGE SCALE
SUPPORT FROM THE ECMWF ALBEIT WITH LESS QPF. PAST EXPERIENCE SHOWS
FOLLOWING THE HIGHER GFS QPF AMOUNTS IS STILL NOT ENOUGH AND THAT
REALITY BRINGS SIGNIFICANTLY MORE RAIN. ASSUMING THE CURRENT MODEL
RUNS STAY UNCHANGED IN THE FUTURE...WOULD EXPECT MULTIPLE MAINSTEM
RIVERS EXCEEDING FLOOD STAGE AS SOON AS SUNDAY MORNING.

WILL BEGIN TO ISSUE SOME OUTLOOK PRODUCTS TODAY WITH THE CAVEAT THAT
MODELS HAVE RELATIVELY RECENTLY SHIFTED THE FOCUS FROM NORTHERN
WASHINGTON/BRITISH COLUMBIA SOUTH TO OUR AREA. ADDITIONAL SHIFTING
IS EXPECTED AS WELL AS TIMING DIFFERENCES. STAY TUNED AS THIS
SITUATION EVOLVES OVER TIME. /JBONK

&&

.PREV DISC... /ISSUED 259 AM PST WED DEC 17 2014/

SHORT TERM...TODAY THROUGH SATURDAY...VERY LIGHT RAIN CONTINUES TO
IMPACT SW WASHINGTON THIS MORNING BUT HAS OTHERWISE STARTED TO
DISSIPATE OVER THE SOUTHERN PORTION OF THE FORECAST AREA. WATER
VAPOR IMAGERY SHOWS A CLOSED LOW WEAKENING AS IT HAS PUSHED ONSHORE
NEAR THE OREGON/CALIFORNIA BORDER...WHILE AN UPPER LEVEL SHORTWAVE
IS ELONGATING AS IT APPROACHES THE PACIFIC NORTHWEST COASTLINE. NOT
MUCH CHANGE IN THE KTTD-KDLS GRADIENT...WHICH REMAINS AROUND -5
EARLY THIS MORNING. EAST WINDS CONTINUE TO GUST NEAR 25 MPH THROUGH
THE GORGE...BUT EXPECT THE EASTERLY GRADIENT TO WEAKEN BY LATE
TONIGHT.

AFTER A PERIOD OF LIGHT RAIN THIS MORNING...MODELS REMAIN CONSISTENT
IN SHOWING AN UPTICK IN PRECIP BY THIS AFTERNOON ASSOCIATED WITH THE
VORT MAX JUST OFFSHORE AROUND 45N 134W. THE LOWER LEVEL MOISTURE
ASSOCIATED WITH THE SURFACE LOW COMBINED WITH THE UPPER LEVEL FORCING
FROM THE SHORTWAVE SHOULD DRIVE A PERIOD OF STEADIER PRECIP THIS
EVENING AND THROUGH TONIGHT. THE VORT MAX PUSHES EAST OF THE CASCADES
BY 12Z THU...AFTER WHICH SHOWER ACTIVITY SHOULD DROP OFF
SIGNIFICANTLY.

WITH CLEARING SKIES AND LIGHT WINDS...SHOULD SEE SOME SHALLOW FOG TO
DEVELOP IN INTERIOR VALLEYS TONIGHT THROUGH EARLY THU MORNING. MODELS
MAINTAIN A THREAT FOR LIGHT PRECIP OVER THE HIGHER TERRAIN MUCH OF
THU...BUT OTHERWISE EXPECT DRY CONDITIONS TO PERSIST TO LOWER
ELEVATIONS. THE NEXT SIGNIFICANT FRONTAL SYSTEM ARRIVES LATE
THU...SPREADING RAIN AND BRINGING GUSTY COASTAL WINDS TO THE REGION
THROUGH FRI. PRECIPITABLE WATER IS EXPECTED TO BE NEAR AN INCH AND AN
APPROACHING JET STREAK SHOULD PROVIDE GOOD LIFT AND EXPECT THE
HIGHEST RAINFALL TOTALS OF 0.75 TO 1 INCH ACROSS THE COAST AND COAST
RANGE THROUGH MIDDAY FRI. OTHER LOCATIONS WILL SEE ON AVERAGE 0.5
INCHES OF RAIN. SNOW LEVELS SHOULD REMAIN ABOVE 5000 FEET DURING THE
PEAK RAIN PERIOD...BUT LOWER TO NEAR OR BELOW THE CASCADE PASSES
BEHIND THE FRONT FRIDAY AFTERNOON.

STRONG LOW PRESSURE OVER THE GULF OF ALASKA WILL PUSH INLAND LATE FRI
INTO EARLY SAT MORNING...SIMULTANEOUSLY FLATTENING A BROAD AREA OF
HIGH PRESSURE OVER THE EASTERN PACIFIC. THERE IS INCREASING
CONFIDENCE AN ATMOSPHERIC RIVER SCENARIO WILL SET UP...WITH ABUNDANT
MOISTURE AIMED DIRECTLY AT THE PACIFIC NORTHWEST SAT.

LONG TERM...SATURDAY NIGHT THROUGH TUESDAY...AS THIS TROUGH MOVES ON
SHORE SATURDAY...THE ASSOCIATED COLD FRONT MOVES ONSHORE AND STALLS
EAST-TO-WEST ACROSS NORTHWEST OREGON AND SOUTHWEST WASHINGTON. THIS
PUTS OUR AREA IN THE PATH OF RAIN STARTING SATURDAY THROUGH MONDAY.
SOME UNCERTAINTY EXISTS IN WHERE THIS BOUNDARY WILL SET UP...WHICH
WILL DETERMINE HOW MUCH RAINFALL WE WILL GET. ON TUESDAY...GEFS
ENSEMBLE SPAGHETTI PLOTS GET MESSY AND SIGNIFICANT DIFFERENCES START
TO SHOW UP BETWEEN THE GFS AND ECMWF...DECREASING CONFIDENCE ON HOW
THE REST OF THE WEEK WILL SHAPE UP.  AS OF NOW...THE MOST COMMON
SOLUTION IS THAT HIGH PRESSURE RIDGING WILL START TO BUILD BACK OVER
THE WESTERN U.S. WHICH SUGGESTS DRIER WEATHER STARTING TUESDAY...
THOUGH UNCERTAINTY IS VERY HIGH. -MCCOY

&&

.AVIATION...VFR CONDITIONS TO PERSIST AT MOST TAF SITES THROUGH
THIS AFTERNOON. AS SHOWERS MOVE IN...THERE MAY BE PERIODS OF
MVFR...ESPECIALLY AT SOUTH WILLAMETTE VALLEY SITES. CLEARING IS
POSSIBLE THIS EVENING...ALLOWING FOG TO DEVELOP IFR CIGS AND
VIS...BUT UNCERTAINTY IS HIGH BECAUSE THE MODELS ARE HINTING AT A
WEAK LOW PRESSURE SYSTEM OFF THE SOUTH OREGON COAST MOVING INLAND
THIS EVENING. THIS COULD BRING ADDITIONAL SHOWERS AND WINDS WHICH
WOULD KEEP CIGS VFR/MVFR. IF ANY CLEARING DOES OCCUR...EXPECT CIGS
AND VIS TO DROP TO IFR WITH THE DEVELOPMENT OF FOG/LOW STRATUS.

KPDX AND APPROACHES...VFR CONDITIONS TO PERSIST WEDNESDAY.
RAIN MAY BRING PERIODS OF MVFR CIGS AND VIS. CIGS COULD DROP TO
IFR TONIGHT WITH THE DEVELOPMENT OF FOG/LOW STRATUS AFTER 09Z
THURSDAY. -MCCOY

&&

.MARINE...WEST SWELL AROUND 10 FT BRINGING SEAS UP TO SMALL CRAFT
CRITERIA TODAY. SEAS DROP BELOW 10 FT LATER THIS EVENING. THE
SYSTEM OF INTEREST WILL BE TOMORROW WHICH WILL LIKELY BRING
SOUTHERLY GALES THROUGH EARLY FRIDAY. THERE IS STILL SOME
UNCERTAINTY ON TIMING...BUT MODELS ARE COMING INTO AGREEMENT THAT
WINDS WILL START TO INCREASE EARLY THURSDAY MORNING...REACHING
GALE FORCE BY EARLY AFTERNOON. SEAS BUILD INTO THE TEENS THURSDAY
AFTERNOON. SEAS DROP BACK DOWN TO 10 TO 12 FT ON FRIDAY AHEAD OF
THE NEXT SYSTEM WHICH WILL BRING SEAS UP EVEN HIGHER ON SATURDAY.

THERE IS STILL UNCERTAINTY ON THE TIMING OF THE SATURDAY SYSTEM...BUT
AS OF NOW MODELS ARE SUGGESTING THAT WINDS COULD AGAIN REACH GALE
FORCE EARLY SATURDAY...WHICH COULD BUILD SEAS INTO THE LOW 20S.
SEAS START TO FALL EARLY SUNDAY...DROPPING BACK INTO THE LOW
TEENS BY LATE SUNDAY OR EARLY MONDAY. AN ACTIVE WEATHER PATTERN
WILL CONTINUE THROUGH THIS WEEKEND...KEEPING SEAS ELEVATED
THROUGH EARLY NEXT WEEK WITH PERIODS OF GALES POSSIBLE. -MCCOY


&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...GALE WATCH FROM THURSDAY MORNING THROUGH THURSDAY EVENING FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 9 PM PST THIS
     EVENING FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST THIS AFTERNOON.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.




000
FXUS66 KPQR 171059
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
259 AM PST WED DEC 17 2014

.SYNOPSIS...A CLOSED LOW JUST OFFSHORE WEST OF THE OR/CA BORDER WILL
SLOWLY WEAKEN AND EVENTUALLY MOVE ONSHORE ALONG THE N OR/S WA COAST
THIS AFTERNOON. THIS WILL MAINTAIN LIGHT SHOWER ACTIVITY...MAINLY
OVER THE HIGHER TERRAIN THIS MORNING. AN UPPER LEVEL SHORTWAVE WILL
PUSH ONSHORE LATER TODAY...LIKELY BRINGING A PERIOD OF STEADIER
RAINFALL THROUGH EARLY THU MORNING. EXPECT A FAIRLY QUIET PERIOD FOR
MUCH OF THE DAY THU...BUT THEN A MORE ORGANIZED FRONT WILL BRING
GUSTY WINDS AND LARGE SURF TO THE COAST...WITH RAIN SPREADING INLAND
THURSDAY NIGHT AND FRIDAY. RISING SNOW LEVELS WILL LIMIT SNOW TO THE
HIGHEST PEAKS...BUT COLDER AIR BEHIND THE FRONT MAY RESULT IN SOME
SNOW SHOWERS FOR THE CASCADES PASSES FRIDAY EVENING AND SATURDAY.
WARMER AND MOISTER WEATHER IS EXPECTED THIS WEEKEND. THERE IS THE
POTENTIAL FOR AN ATMOSPHERIC RIVER TYPE SET UP AND ASSOCIATED HEAVY
RAIN TO DEVELOP OVER THE WEEKEND INTO EARLY NEXT WEEK.

&&

.SHORT TERM...TODAY THROUGH SATURDAY...VERY LIGHT RAIN CONTINUES TO
IMPACT SW WASHINGTON THIS MORNING BUT HAS OTHERWISE STARTED TO
DISSIPATE OVER THE SOUTHERN PORTION OF THE FORECAST AREA. WATER VAPOR
IMAGERY SHOWS A CLOSED LOW WEAKENING AS IT HAS PUSHED ONSHORE NEAR
THE OREGON/CALIFORNIA BORDER...WHILE AN UPPER LEVEL SHORTWAVE IS
ELONGATING AS IT APPROACHES THE PACIFIC NORTHWEST COASTLINE. NOT MUCH
CHANGE IN THE KTTD-KDLS GRADIENT...WHICH REMAINS AROUND -5 EARLY THIS
MORNING. EAST WINDS CONTINUE TO GUST NEAR 25 MPH THROUGH THE
GORGE...BUT EXPECT THE EASTERLY GRADIENT TO WEAKEN BY LATE TONIGHT.

AFTER A PERIOD OF LIGHT RAIN THIS MORNING...MODELS REMAIN CONSISTENT
IN SHOWING AN UPTICK IN PRECIP BY THIS AFTERNOON ASSOCIATED WITH THE
VORT MAX JUST OFFSHORE AROUND 45N 134W. THE LOWER LEVEL MOISTURE
ASSOCIATED WITH THE SURFACE LOW COMBINED WITH THE UPPER LEVEL FORCING
FROM THE SHORTWAVE SHOULD DRIVE A PERIOD OF STEADIER PRECIP THIS
EVENING AND THROUGH TONIGHT. THE VORT MAX PUSHES EAST OF THE CASCADES
BY 12Z THU...AFTER WHICH SHOWER ACTIVITY SHOULD DROP OFF
SIGNIFICANTLY.

WITH CLEARING SKIES AND LIGHT WINDS...SHOULD SEE SOME SHALLOW FOG TO
DEVELOP IN INTERIOR VALLEYS TONIGHT THROUGH EARLY THU MORNING. MODELS
MAINTAIN A THREAT FOR LIGHT PRECIP OVER THE HIGHER TERRAIN MUCH OF
THU...BUT OTHERWISE EXPECT DRY CONDITIONS TO PERSIST TO LOWER
ELEVATIONS. THE NEXT SIGNIFICANT FRONTAL SYSTEM ARRIVES LATE
THU...SPREADING RAIN AND BRINGING GUSTY COASTAL WINDS TO THE REGION
THROUGH FRI. PRECIPITABLE WATER IS EXPECTED TO BE NEAR AN INCH AND AN
APPROACHING JET STREAK SHOULD PROVIDE GOOD LIFT AND EXPECT THE
HIGHEST RAINFALL TOTALS OF 0.75 TO 1 INCH ACROSS THE COAST AND COAST
RANGE THROUGH MIDDAY FRI. OTHER LOCATIONS WILL SEE ON AVERAGE 0.5
INCHES OF RAIN. SNOW LEVELS SHOULD REMAIN ABOVE 5000 FEET DURING THE
PEAK RAIN PERIOD...BUT LOWER TO NEAR OR BELOW THE CASCADE PASSES
BEHIND THE FRONT FRIDAY AFTERNOON.

STRONG LOW PRESSURE OVER THE GULF OF ALASKA WILL PUSH INLAND LATE FRI
INTO EARLY SAT MORNING...SIMULTANEOUSLY FLATTENING A BROAD AREA OF
HIGH PRESSURE OVER THE EASTERN PACIFIC. THERE IS INCREASING
CONFIDENCE AN ATMOSPHERIC RIVER SCENARIO WILL SET UP...WITH ABUNDANT
MOISTURE AIMED DIRECTLY AT THE PACIFIC NORTHWEST SAT.

.LONG TERM...SATURDAY NIGHT THROUGH TUESDAY...AS THIS TROUGH MOVES ON
SHORE SATURDAY...THE ASSOCIATED COLD FRONT MOVES ONSHORE AND STALLS
EAST-TO-WEST ACROSS NORTHWEST OREGON AND SOUTHWEST WASHINGTON. THIS
PUTS OUR AREA IN THE PATH OF RAIN STARTING SATURDAY THROUGH MONDAY.
SOME UNCERTAINTY EXISTS IN WHERE THIS BOUNDARY WILL SET UP...WHICH
WILL DETERMINE HOW MUCH RAINFALL WE WILL GET. ON TUESDAY...GEFS
ENSEMBLE SPAGHETTI PLOTS GET MESSY AND SIGNIFICANT DIFFERENCES START
TO SHOW UP BETWEEN THE GFS AND ECMWF...DECREASING CONFIDENCE ON HOW
THE REST OF THE WEEK WILL SHAPE UP.  AS OF NOW...THE MOST COMMON
SOLUTION IS THAT HIGH PRESSURE RIDGING WILL START TO BUILD BACK OVER
THE WESTERN U.S. WHICH SUGGESTS DRIER WEATHER STARTING TUESDAY...
THOUGH UNCERTAINTY IS VERY HIGH. -MCCOY

&&

.AVIATION...VFR CONDITIONS TO PERSIST AT MOST TAF SITES THROUGH
WEDNESDAY AFTERNOON. THE QUESTION STILL REMAINS WHETHER LOW LEVEL
STRATUS/FOG WILL DEVELOP IN THE CENTRAL AND SOUTH WILLAMETTE
VALLEY. IF LOW LEVEL STRATUS/FOG DOES DEVELOP EXPECT IT TO CLEAR
OUT BY EARLY WEDNESDAY AFTERNOON. BRIEF PERIODS OF MVFR TO IFR
CIGS AND VIS ARE POSSIBLE UNDER LIGHT TO MODERATE RAIN BANDS
THROUGH LATE WEDNESDAY. WITH CLEARING EXPECTED LATE WEDNESDAY WE
WILL LIKELY SEE THE DEVELOPMENT OF IFR CIGS AND VIS DUE TO LOW
LEVEL STRATUS/FOG RETURNING TO PORTIONS OF THE VALLEY.

KPDX AND APPROACHES...VFR CONDITIONS TO PERSIST WEDNESDAY.
HOWEVER...BRIEF PERIODS OF MVFR CIGS AND VIS ARE POSSIBLE UNDER
LIGHT TO MODERATE RAIN BANDS THROUGH WEDNESDAY AFTERNOON. /64

&&

.MARINE...RATHER BENIGN CONDITIONS TO CONTINUE THROUGH EARLY
THURSDAY AS A WEAK LOW PRESSURE SYSTEM MOVES INLAND OVER NORTHERN
CALIFORNIA. EXPECT SEAS TO REMAIN BELOW 10 FT WITH GUST TO 20 KT
POSSIBLE. ANOTHER LOW PRESSURE SYSTEM CONTINUES TO STRENGTHEN
OFFSHORE AND LOOKS TO MOVE ACROSS THE COASTAL WATERS ON THURSDAY.
THIS SYSTEM WILL LIKELY BRING SOUTHERLY GALES THURSDAY THROUGH
EARLY FRIDAY...BUT THERE IS STILL SOME UNCERTAINTY ON THE EXACT
TIMING. SEAS WITH THIS SYSTEM ARE EXPECTED TO BUILD INTO THE UPPER
TEENS TO THE LOW 20S BY SATURDAY MORNING. AN ACTIVE WEATHER
PATTERN WILL CONTINUE THROUGH NEXT WEEK AND COULD BRING MORE
SOUTHERLY GALES AND ELEVATED SEAS. /64

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.

WA...NONE.

PZ...GALE WATCH FROM THURSDAY MORNING THROUGH THURSDAY EVENING FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 11 AM
    THIS MORNING TO 4 PM PST THIS AFTERNOON.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.





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