Coastal Flood in Oregon, December 8 to 9, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
357 AM PST TUE DEC  8 2015

.SYNOPSIS...ANOTHER FRONT WILL BRING RAIN AND WINDY CONDITIONS TO
THE REGION AGAIN TODAY INTO WED...WITH ANOTHER ROUND OF RAIN AND WIND
WED NIGHT AND THU. THEN COOLER AND SHOWERY FRI INTO THIS WEEKEND WITH
SNOW LEVELS AROUND THE CASCADES PASSES.

&&

.SHORT TERM...TODAY THROUGH THURSDAY...SATELLITE LOOP SHOWING PARENT
LOW CENTER IN THE GULF OF ALASKA NEAR 52N 149W. THE OCCLUDED FRONT
EXTENDS TO THE SE OF THE THE LOW WITH THE COLD FRONT EXTENDING TO THE
SW OF THE TRIPLE POINT. THE WARM FRONT EXTENDS TOWARD THE WA COAST.
A SHORTWAVE ON THE COLD FRONT IS NEAR 40N 148W WHICH WILL COME INTO
PLAY LATER.  THE HEAVY FROM THE WARM FRONT WILL BE DIRECTED TOWARD
THE OLYMPIC MOUNTAINS IN WESTERN WA TODAY AND CLIPPING THE SOUTH WA
COAST AND NORTH OREGON COAST. THE COLD FRONT WILL MOVE TO THE COAST
LATER THIS AFTERNOON AND THE SHORTWAVE WILL ENHANCE WINDS AND RAIN
RATES IN THE WELL MOISTENED AIR MASS. SATELLITE PRECIPITABLE WATER
ESTIMATES AROUND 1.3 TO 1.5 INCHES AND SOUTHWEST WINDS IN THE LOWER
ATMOSPHERE WILL BE EFFICIENT MAINTAINING THE MOISTURE FEED INTO THE
STORM. TONIGHT THE COLD FRONT WILL SLOWLY SAG TO THE SOUTH BRINGING
THE MODERATE TO HEAVY RAIN INTO THE INTERIOR LOWLANDS.	DO NOT EXPECT
THE PROLONGED HEAVY RAIN AS THE EVENT ON MONDAY. HOWEVER WILL NEED TO
MONITOR THE POTENTIAL FOR A SECONDARY WAVE DEVELOPING ALONG THE FRONT
TO SLOW ITS PROGRESS AND INCREASE FLOODING CONCERNS PARTICULARLY FOR
THE COASTAL RIVERS AND POSSIBLY IN THE NORTH VALLEY.	FORTUNATELY
THE BREAK IN THE RAIN OVERNIGHT HAS ALLOWED THE FASTER RESPONDING
RIVERS TO RECEDE.

WIND WILL ALSO BE AN ISSUE WITH THIS SYSTEM. STRONG SOUTHERLY WINDS
TO DEVELOP OVER AREA BEHIND THE WARM FRONT. THERE SHOULD
BE ENOUGH GRADIENT TO SUPPORT GUSTS OF 60 TO 70 MPH WINDS ON THE
COAST AND EXPOSED RIDGES IN THE COASTAL MOUNTAINS...WITH GUSTS 50 TO
65 MPH FOR THE COASTAL COMMUNITIES. LIKELY SEE THESE WINDS PERSIST
THROUGH THE MORNING AND WELL INTO THE AFTERNOON BEFORE EASING IN THE
EVENING.  AS THE COLD FRONT SHIFTS CLOSER TO THE INTERIOR ZONES WE
COULD ALSO SEE GUSTY WINDS FOR THE INTERIOR LOWLAND ZONES TONIGHT.
WITH THE SATURATED SOILS FEEL CONFIDENT ENOUGH TO ISSUE THE WARNING
FOR THE CENTRAL AND NORTH WILLAMETTE VALLEY AS WELL AS CLARK COUNTY.

STRONG WINDS ALSO EXPECTED IN THE CASCADES GENERALLY ABOVE 4000 FEET
SO WILL UPGRADE THE WATCH TO A WARNING FOR THAT AREA. SOUTHWEST WIND
35 TO 45 MPH WITH GUSTS LIKELY 70 TO 75 MPH. EXPOSED RIDGES CAN SEE
GUSTS TO 80-90 MPH.

THE COLD FRONT MOVES THROUGH LATE TONIGHT INTO EARLY WED. THE CST
MODELS IN GOOD GENERAL AGREEMENT WITH THE TIMING OF THE
FRONT...BRINGING IT INTO THE CASCADES BY DAYBREAK WED...THEN EAST OF
THE CASCADES DURING WED MORNING. EXPECT A BREAK FROM THE HEAVY RAIN
AND WIND FOR THE REST OF THE DAY WED WITH ONLY SOME RELATIVELY LIGHT
POST FRONTAL SHOWERS REMAINING. SNOW LEVELS WILL REMAIN WELL ABOVE
6000 FT DURING MOST OF THE FRONTAL PRECIPITATION TUE NIGHT...BUT WILL
THEN DROP CONSIDERABLY ON THE BACKSIDE OF THE FRONT. THIS WILL LIKELY
ALLOW THE CASCADE PASSES TO PICK UP A COUPLE INCHES OF SNOW ON WED.

YET ANOTHER LOW PRES SYSTEM IS EXPECTED TO FORM ALONG THE STALLED
BAROCLINIC ZONE AND AFFECT THE PAC NW WED NIGHT INTO THU. THIS SYSTEM
APPEARS TO HAVE THE POTENTIAL TO BE QUITE STRONG...WITH THE FCST
MODELS INDICATING A SURFACE LOW WITH A CENTRAL PRES APPROACHING
960-965 MB RANGE. HOWEVER...FCST CONFIDENCE IN THE DETAILS ON TIMING
AND POSITIONING OF THIS SYSTEM ARE IMPROVING. WITH THE LOW SITTING
OFF THE NORTH WA COAST OR OFF VANCOUVER ISLAND ON THURSDAY. THIS MAY
BE ENOUGH FOR HIGH WINDS AT THE COAST.	 /MH

.LONG TERM...THURSDAY NIGHT THROUGH MONDAY...
A FAIRLY COLD AND BROAD UPPER LEVEL TROUGH IS MODELED TO DIG INTO
THE PAC NW TO END THE WEEK...WITH QUITE A BIT OF SHOWER ACTIVITY
LIKELY AROUND ON FRI AND PRECIPITATION FALLING AS SNOW IN THE
CASCADES. FCST CONFIDENCE DECREASES GOING INTO THE WEEKEND AND EARLY
NEXT WEEK. HOWEVER...IT DOES APPEAR THAT A MORE PROGRESSIVE PATTERN
PREVAILS. FOR NOW...WILL KEEP TEMPS AND POPS NEAR CLIMO AND WAIT
UNTIL MODEL AGREEMENT INCREASES BEFORE TRYING TO ADD MUCH DETAIL TO
THE FCST. PYLE /MH

&&

.AVIATION...MOIST SOUTHWESTERLY FLOW AND LOW LEVEL SOUTHERLY WINDS
WILL BRING MAINLY A MIX OF MVFR AND VFR CONDITIONS FOR INTERIOR TAF
SITES AND A MIX OF IFR AND MVFR CONDITIONS ALONG THE COAST THROUGH
12Z WEDNESDAY. KONP WILL LIKELY EXPERIENCE THE MOST FLIGHT
RESTRICTIONS OVER THE NEXT 24 HOURS...POSSIBLY STAYING ALMOST
ENTIRELY IN LIFR TO IFR FLIGHT CONDITIONS FOR THE PERIOD WITH SOUTH
WIND GUSTS INCREASING INTO THE 40 TO 50 KT RANGE AFTER 00Z WEDNESDAY.
INCREASING SOUTH WINDS IN THE WILLAMETTE VALLEY SHOULD HELP TO KEEP
KSLE AND KEUG PREDOMINANTLY VFR TODAY AND PERHAPS EVEN THE PORTLAND
METRO TAF SITES. HOWEVER...THESE MORE NORTHERN TAF SITES WILL BE
CLOSER TO A STEADIER RAIN BAND THAT WILL DEVELOP OVER FAR NORTHWEST
OREGON AND SOUTHWEST WASHINGTON...WHICH COULD RESULT IN SOME
DETERIORATION AT THESE TERMINALS TOWARDS 00Z WEDNESDAY AND POINTS
AFTERWARD.

KPDX AND APPROACHES...EXPECT A MIX OF MVFR AND VFR CONDITIONS
THROUGH THIS MORNING AS A WARM FRONT BRINGS LIGHT RAIN SHOWERS TO
THE TERMINAL. INCREASING SOUTH WINDS TOWARDS 18Z TUESDAY SHOULD KEEP
ANY IFR CONDITIONS THAT DEVELOP FROM PERSISTING FOR AN EXTENDED
PERIOD. A FRONTAL RAIN BAND WILL SHIFT SOUTHWARD TOWARDS THE
TERMINAL AROUND 00Z TO 06Z WEDNESDAY. CONDITIONS WILL LIKELY
DETERIORATE MORE SOLIDLY INTO MVFR CONDITIONS AFTERWARDS. /NEUMAN

&&

.MARINE...WINDS BEGINNING TO INCREASE AGAIN AS A WARM FRONT
CONTINUES PUSHING NORTH ACROSS THE WATERS. A COLD FRONT WILL DRAG
SOUTH THIS AFTERNOON. BETWEEN THE TWO FRONTS...WILL SEE SOMEWHAT
OF A COASTAL JET DEVELOP WITH WIND GUSTS EXPECTED TO HOVER BETWEEN
40 TO 45 KT THROUGH EARLY AFTERNOON. AS THE FRONT MOVES SOUTH
TODAY...THE NORTHERN REACHES OF THE NORTHER WATERS STAND TO SEE A
SEVERAL HOUR BREAK IN WINDS THIS AFTERNOON AND EVENING. HAVE
CONCERNS...HOWEVER...THAT THE JET MAY INTENSIFY AND BECOME
ESPECIALLY FOCUSED ACROSS THE CENTRAL WATERS FROM ABOUT 20 NM
INLAND. 06Z MODELS SHOW A VERY SMALL SCALE SURFACE LOW DEVELOPING
ALONG THE NORTHERN EDGE OF THE FRONT AND WELL OFF THE MOUTH OF
THE COLUMBIA THIS AFTERNOON. THEY THEN TAKE IT NORTHEASTWARD THIS
EVENING TO THE STRAIT OF JUAN DE FUCA AFTER MIDNIGHT. THIS MAY
PROVIDE A FOCUS OF MARGINAL STORM FORCE WINDS SOUTH OF TILLAMOOK
BAR LATER THIS EVENING AND OVERNIGHT AS THE BOUNDARY LIFTS BACK
NORTH AS A WARM FRONT AGAIN AFTER MIDNIGHT AND BRINGING THE GALES
BACK WITH IT. DECIDED THAT THE BREAK IN WINDS WAS COMPARATIVELY
SHORT FOR THE BULK OF THE NORTHERN WATERS AND RELUCTANTLY DECIDED
TO EXTEND THE WARNING COVERING THE ENTIRE TIME PERIOD UNTIL WINDS
EASE LATER WEDNESDAY MORNING.

THE CONCERN WILL THEN SHIFT TO A VERY DEEP SURFACE LOW PRESSURE
SYSTEM...SOMEWHERE ON THE ORDER OF 960 TO 970MB...THAT IS
EXPECTED TO DEVELOP IN THE NORTHEAST PACIFIC OCEAN. THE EC AND GFS
REMAIN IN RELATIVELY GOOD AGREEMENT THAT THIS SYSTEM WILL SPIN UP
AND MOVE NORTHEASTWARD TOWARDS THE WATERS BETWEEN VANCOUVER ISLAND
AND HAIDA GWAII. A NEGATIVELY TILTED OCCLUSION WILL LIKELY BRING A
BOUT OF HIGH END GALE FORCE TO LOW END STORM FORCE WINDS TO THE
WATERS ON WEDNESDAY NIGHT OR THURSDAY. IN ADDITION...WAVE MODELS
HAVE FLUCTUATED BETWEEN A 25 TO 40 FT WESTERLY SWELL AT
APPROXIMATELY 15 TO 17 SECONDS MOVING INTO THE WATERS SOME TIME
THURSDAY/FRIDAY. FOR NOW...WENT WITH A MIDDLE OF THE ROAD
APPROACH TOWARD SEA HEIGHTS IN COLLABORATION WITH SURROUNDING
OFFICES. EITHER WAY...BESIDES BRINGING EXTREMELY DANGEROUS SEA
CONDITIONS TO THE WATERS DURING THIS PERIOD...WAVES THIS SIZE FROM
A WESTERLY DIRECTION WILL ALMOST CERTAINLY BRING HIGH SURF
CONDITIONS AND COASTAL FLOODING. AS A RESULT...THE CURRENT
COASTAL FLOOD WATCH LOOKS TO BE IN GOOD SHAPE.

IN ADDITION...THE HIGH RIVER FLOWS ACROSS THE REGION COUPLED WITH
TIDAL ANOMALIES OF 1 TO 2 FT AND HIGHER THAN NORMAL TIDES...WILL
LIKELY RESULT IN SOME MINOR TIDAL OVERFLOW FLOODING ALONG OUR
COAST. AT THIS POINT...THE TIDES OF CONCERN WILL BE AROUND 10 TO
11 AM TUESDAY AND WEDNESDAY MORNING AND THE CURRENT TIDAL OVERFLOW
ADVISORY LOOKS ON TRACK. JBONK/NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR 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 WIND WARNING FROM 4 PM THIS AFTERNOON TO 4 AM PST
    WEDNESDAY FOR CASCADES IN LANE COUNTY-NORTHERN OREGON CASCADES.

     WIND ADVISORY FROM 1 PM THIS AFTERNOON TO 4 AM PST WEDNESDAY
    FOR CENTRAL WILLAMETTE VALLEY-GREATER PORTLAND METRO AREA.

     HIGH WIND WARNING UNTIL 4 AM PST WEDNESDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

     COASTAL FLOOD WATCH FROM THURSDAY MORNING THROUGH FRIDAY M
     MORNING FOR CENTRAL OREGON COAST-NORTH OREGON COAST.

     COASTAL FLOOD ADVISORY FROM 8 AM THIS MORNING TO 1 PM PST THIS
     AFTERNOON FOR CENTRAL OREGON COAST-NORTH OREGON COAST.

     COASTAL FLOOD ADVISORY FROM 8 AM TO 1 PM PST WEDNESDAY FOR
     CENTRAL OREGON COAST-NORTH OREGON COAST.

     HIGH WIND WARNING FROM 10 AM THIS MORNING TO 4 AM PST WEDNESDAY
     FOR CENTRAL COAST RANGE OF WESTERN OREGON-COAST RANGE OF
     NORTHWEST OREGON.

WA...FLOOD WATCH THROUGH THURSDAY 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 WIND WARNING FROM 4 PM THIS AFTERNOON TO 4 AM PST
     WEDNESDAY FOR SOUTH WASHINGTON CASCADES.

     WIND ADVISORY FROM 1 PM THIS AFTERNOON TO 4 AM PST WEDNESDAY
     FOR GREATER VANCOUVER AREA.

     HIGH WIND WARNING UNTIL 4 AM PST WEDNESDAY FOR SOUTH WASHINGTON
     COAST.

     COASTAL FLOOD WATCH FROM THURSDAY MORNING THROUGH FRIDAY
     MORNING FOR SOUTH WASHINGTON COAST.

     COASTAL FLOOD ADVISORY FROM 8 AM THIS MORNING TO 1 PM PST THIS
     AFTERNOON FOR SOUTH WASHINGTON COAST.

     COASTAL FLOOD ADVISORY FROM 8 AM TO 1 PM PST WEDNESDAY FOR
     SOUTH WASHINGTON COAST.

     HIGH WIND WARNING FROM 10 AM THIS MORNING TO 4 AM PST WEDNESDAY
     FOR WILLAPA HILLS.

PZ...GALE WARNING UNTIL 10 AM PST WEDNESDAY FOR COASTAL WATERS FROM
     CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 10 AM
     PST WEDNESDAY.

&&

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.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PORTLAND OR
911 AM PST TUE DEC 08 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0430 PM     FLOOD            VERNONIA                45.86N 123.18W
12/07/2015                   COLUMBIA           OR   OTHER FEDERAL

            THE NEHALEM RIVER NEAR VERNONIA CRESTED AT 12.26 FEET AT
            430 PM. FLOOD STAGE IS AT 12.0 FEET.

0430 PM     FLOOD            TRASK                   45.42N 123.64W
12/07/2015                   TILLAMOOK          OR   OTHER FEDERAL

            THE TRASK RIVER NEAR TILLAMOOK CRESTED AT 17.97 FEET AT
            430 PM. FLOOD STAGE IS 16.5 FEET.

0445 PM     FLOOD            MAPLETON                44.03N 123.87W
12/07/2015                   LANE               OR   OTHER FEDERAL

            THE SIUSLAW RIVER NEAR MAPLETON CRESTED AT 18.36 FEET AT
            445 PM. FLOOD STAGE IS 18.0 FEET.

0500 PM     FLOOD            SILETZ                  44.72N 123.92W
12/07/2015                   LINCOLN            OR   OTHER FEDERAL

            THE SILETZ RIVER NEAR SILETZ CRESTED AT 21.5 FEET AT 5
            PM. FLOOD STAGE IS 16.0 FEET. MODERATE FLOOD STAGE IS
            20.0 FEET.

0530 PM     FLOOD            6 E TILLAMOOK           45.46N 123.71W
12/07/2015                   TILLAMOOK          OR   OTHER FEDERAL

            THE WILSON RIVER NEAR TILLAMOOK CRESTED AT 15.75 FEET AT
            530 PM. FLOOD STAGE IS 12.0 FEET. MODERATE FLOOD STAGE IS
            15.5 FEET.

0545 PM     FLOOD            GRESHAM                 45.50N 122.44W
12/07/2015                   MULTNOMAH          OR   OTHER FEDERAL

            THE JOHNSON CREEK NEAR SYCAMORE CRESTED AT 15.33 FEET AT
            545 PM. FLOOD STAGE IS 11.0 FEET. MAJOR FLOOD STAGE IS
            14.0 FEET.

0630 PM     FLOOD            TIDEWATER               44.42N 123.90W
12/07/2015                   LINCOLN            OR   OTHER FEDERAL

            THE ALSEA RIVER NEAR TIDEWATER CRESTED AT 17.89 FEET AT
            630 PM. FLOOD STAGE IS 18.0 FEET.

0630 PM     FLOOD            FOSS                    45.70N 123.75W
12/07/2015                   TILLAMOOK          OR   OTHER FEDERAL

            THE NEHALEM RIVER NEAR FOSS CRESTED AT 15.43 FEET AT 630
            PM. FLOOD STAGE IS AT 15.0 FEET.

0700 PM     FLOOD            GRAYS RIVER             46.35N 123.60W
12/07/2015                   WAHKIAKUM          WA   OTHER FEDERAL

            THE GRAYS RIVER NEAR ROSBURG CRESTED AT 12.01 FEET AT 7
            PM. FLOOD STAGE IS AT 12.0 FEET.

0830 PM     FLOOD            ESTACADA                45.29N 122.33W
12/07/2015                   CLACKAMAS          OR   OTHER FEDERAL

            THE CLACKAMAS RIVER NEAR ESTACADA CRESTED AT 20.65 FEET
            AT 830 PM. FLOOD STAGE IS 20.0 FEET.

1247 AM     DEBRIS FLOW      SWEET HOME              44.40N 122.70W
12/08/2015                   LINN               OR   BROADCAST MEDIA

            MAJOR ROCKSLIDE ON US HIGHWAY 20 JUST EAST OF SWEET HOME.
            ONE LANE STILL BLOCKED BY THE SLIDE.

0245 AM     FLOOD            DILLEY                  45.48N 123.12W
12/08/2015                   WASHINGTON         OR   OTHER FEDERAL

            THE TUALATIN RIVER NEAR DILLEY CRESTED AT 17.85 FEET AT
            245 AM. FLOOD STAGE IS 17.5 FEET.

0530 AM     FLOOD            SUVER                   44.75N 123.20W
12/08/2015                   POLK               OR   OTHER FEDERAL

            THE LUCKIAMUTE RIVER NEAR SUVER CRESTED AT 30.26 FEET AT
            530 AM. FLOOD STAGE IS 27.0 FEET.

&&

LBRACKETT