High Wind in Washington, December 5, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
450 AM PST SAT DEC 5 2015

UPDATED AVIATION DISCUSSION

.SYNOPSIS...THE WARM FRONT WITH THE NEXT STRONG MOIST FRONTAL SYSTEM
OFF THE COAST WILL SPREAD ONTO THE COAST AND IN THE NORTHERN VALLEY
AREAS TODAY FOR RAIN...HEAVIEST ON THE SOUTH WASHINGTON COAST...AS
WELL AS STRONG WINDS ALONG THE COAST NEAR THE BEACHES AND HEADLANDS.
THE ASSOCIATED COLD FRONT WILL SWEEP ONSHORE TONIGHT AND EARLY SUNDAY
WITH MORE RAIN OVER THE WHOLE FORECAST AREA...FOLLOWED BY DECREASING
SHOWERS THE REMAINDER OF SUNDAY. ANOTHER STRONG MOIST FRONTAL SYSTEM
WILL MOVE INTO SOUTHWEST WASHINGTON AND NORTHWEST OREGON SUNDAY
NIGHT...REINFORCED BY A SECOND SURGE OF ENERGY MONDAY. THIS SYSTEM
WILL PRODUCE MORE AND POSSIBLY HEAVIER RAIN OVER THE AREA...AND
ANOTHER ROUND OF STRONG WINDS ALONG THE COAST THAT MAY REACH INLAND
BY MONDAY. AT LEAST A COUPLE OF MORE WET SYSTEMS ARE LIKELY TO AFFECT
THE REGION FROM TUESDAY THROUGH THE END OF THE WEEK.
ALL OF THIS RAIN HAS A DECENT CHANCE OF CAUSING SOME FLOODING AROUND
THE AREA ESPECIALLY NEXT WEEK.
&&

.SHORT TERM...TODAY THROUGH MONDAY...WE HAD A BRIEF BREAK IN THE
PRECIPITATION OVERNIGHT AS WE WERE IN BETWEEN SYSTEMS. HOWEVER...
CLOUDS ARE ALREADY BEGINNING TO INCREASE EARLY THIS MORNING FROM THE
WARM FRONT WITH THE NEXT MOIST STRONG FRONTAL SYSTEM. NATIONAL
WEATHER SERVICE DOPPLER RADAR SHOWS ECHOES INCREASING ALONG THE COAST
AND BEGINNING TO MOVE ONSHORE. THE WARM FRONTAL PRECIPITATION WILL
SPREAD INLAND ESPECIALLY IN THE NORTH THIS MORNING AS THE COLD FRONT
STALLS OFF THE COAST. THE GREATEST AMOUNT OF RAIN WILL BE ON THE
SOUTH WASHINGTON COAST TODAY.

WE WILL ALSO SEE STRONG WINDS OVER THE COASTAL WATERS...AND BUOY 89
60 NM OFFSHORE ALREADY HAS A PEAK WIND OF 47 KT...SO OUR STORM
WARNING OVER THE COASTAL WATERS LOOKS GOOD. LOOK FOR HIGH WINDS ALONG
THE COASTAL STRIP AS WELL. THE GRADIENT IS PRETTY EASTERLY... BUT THE
WINDS WILL LIKELY BE STRONG ENOUGH TO WARRANT THE CURRENT HIGH WIND
WARNING AT THE BEACHES AND HEADLANDS...BUT MAY PREVENT COASTAL
COMMUNITIES FROM REACHING CRITERIA UNLESS IT IS VERY BRIEFLY AS THE
FRONT MOVES ONSHORE TONIGHT.

THE ASSOCIATED COLD FRONT SWEEPS THROUGH SOUTHWEST WASHINGTON AND
NORTHWEST OREGON TONIGHT AND EARLY SUNDAY WITH RAIN ACROSS ALL OF THE
AREA. HOWEVER...THERE IS A FAIR AMOUNT OF ENERGY DIGGING SOUTH INTO
NORTHERN CALIFORNIA WITH THIS FRONT...AND THAT MAY LIMIT HOW STRONG
AND WET THE FRONT WILL BE AS IT MOVES INLAND TONIGHT.

ONCE THE FRONT MOVES INLAND SUNDAY MORNING...THE REMAINDER OF SUNDAY
WILL SEE DECREASING SHOWERS.

SNOW LEVELS WILL THIS EVENT WILL BE RELATIVELY HIGH...EXCEPT NEAR THE
CASCADE CREST FROM ABOUT MOUNT HOOD NORTHWARD THROUGH THE SOUTH
WASHINGTON CASCADES AS COLD AIR DAMMING AND EAST WINDS RETURN AND
LOWER THE SNOW LEVEL IN THAT AREA. PRECIPITATION AMOUNTS WILL BE
RELATIVELY LIGHT TODAY...SO ONLY A COUPLE OF INCHES OF SNOW ARE
EXPECTED. THE RAIN PICKS UP TONIGHT...BUT ALSO EXPECT THE SNOW LEVEL
TO RISE...AND THIS WILL PROBABLY LIMIT SNOW ACCUMULATIONS FROM BEING
MORE THAN A FEW INCHES. THE MOST PRONE AREAS WILL BE AROUND TROUT
LAKE WA AND NORTHWARD TOWARD MOUNT ADAMS.

THE NEXT EVEN STRONGER AND WET FRONTAL SYSTEM IS EXPECTED TO MOVE
INTO SOUTHWEST WASHINGTON AND NORTHWEST OREGON SUNDAY NIGHT AND
MONDAY. DETAILS WITH THIS SYSTEM HAVE BEEN A BIT FLUID...SO TO
SPEAK...BUT RECENT MODEL RUNS ARE INDICATING THE FIRST WAVE OF
MOISTURE AND WIND ARE EXPECTED SUNDAY NIGHT. LOOK FOR STORM FORCE
WINDS AGAIN OVER THE COASTAL WATERS AND HIGH WINDS ALONG THE COAST. A
SECOND WAVE IS EXPECTED MONDAY...WITH MORE HEAVY RAIN AND STRONG
COASTAL WIND THAT MAY ALSO SPREAD INLAND THIS TIME.

DO NOT EXPECT ANY FLOODING WITH THE SYSTEM THAT AFFECTS THE AREA
TODAY INTO SUNDAY. HOWEVER...WE WILL NEED TO WATCH SUBSEQUENT
SYSTEMS...BEGINNING WITH THE SUNDAY NIGHT AND MONDAY SERIES...AS WELL
AS SYSTEMS TUESDAY AND BEYOND. THE CURRENT HYDROLOGIC OUTLOOK COVERS
THIS AS WELL AS IT CAN AT THIS POINT. TOLLESON

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
MONDAY NIGHT THROUGH FRIDAY. ACTIVE WEATHER PATTERN CONTINUES INTO
NEXT WEEK. WE GET SOMEWHAT OF A BREAK MONDAY NIGHT INTO TUESDAY...
WITH ONLY A FEW SHOWERS STILL LINGERING AROUND THE AREA. DURING THIS
TIME THE MOISTURE PLUME FROM THE MONDAY SYSTEM SHIFTS NORTH OF OUR
AREA...BEFORE DROPPING BACK SOUTH WITH THE NEXT LOW PRESSURE SYSTEM
TUESDAY AFTERNOON INTO WEDNESDAY. THE MODELS HAVE A LOT OF MOISTURE
WITH BOTH OF THESE SYSTEMS...SO WE ARE ANTICIPATING A VERY WET WEEK
WITH SIGNIFICANT ACCUMULATIONS LIKELY THROUGH WEDNESDAY. DUE TO THE
TROPICAL AIRMASS SOURCING THE MOISTURE FOR THESE SYSTEMS...SNOW
LEVELS REMAIN UP ABOVE 7000 FT THROUGH THE FIRST HALF OF NEXT WEEK.
SNOW LEVELS DROP BACK DOWN TO BELOW PASS LEVELS BEHIND THE
TUESDAY-WEDNESDAY SYSTEM...WITH ACTIVE WEATHER PATTERN CONTINUING
INTO THE WEEKEND. THEREFORE...SNOW COULD IMPACT TRAVEL THROUGH THE
CASCADES STARTING WEDNESDAY AFTERNOON THROUGH THE END OF THE WEEK.
THE SYSTEMS LATER IN THE WEEK DON'T HAVE THE LONG MOISTURE FETCH LIKE
THE MONDAY-WEDNESDAY SYSTEMS...SO RAINFALL AMOUNTS SHOULD BE LESS
LATER IN THE WEEK. -MCCOY
&&

.AVIATION...12Z TAFS...VFR TO START HOWEVER A LOWER MVFR DECK IS
JUST STARTING TO APPEAR AT KONP. MODELS NOT SHOWING THAT AND WILL
SEE IF IT STICKS. OTHERWISE...EXPECT CIGS WILL CONTINUE TO LOWER
BUT LARGELY REMAIN VFR OVER THE COURSE OF THE NEXT SEVERAL HOURS
AS THE WARM FRONTAL PORTION OF THE SYSTEM PASSES BY. COASTAL AREAS
WILL SEE CIGS LARGELY STAY PUT AS THE COLD FRONT APPROACHES...HOWEVER
THE INLAND TERMINALS SHOULD SEE SOME IMPROVEMENT AHEAD OF THE
COLD FRONT. MOST TERMINALS WILL SEE CIGS AND/OR VSBYS LOWER TO
MVFR UNDER THE COLD FRONTAL INFLUENCE. EXPECT THE COAST TO DROP
AROUND 00-01Z WITH INLAND SITES WAITING UNTIL CLOSER TO 06-08Z AS
THE COLD FRONT STALLS. KTTD WILL CONTINUE TO SEE EAST WINDS 15-20
KT WITH GUSTS NEARING 30 KT THIS MORNING. KAST AND KONP WILL SEE
SOUTHERLY WINDS INCREASE TO DAY UNDER A COASTAL JET INFLUENCE
REACHING 20-25 KT AND GUSTS 30-35 KT.

KPDX AND APPROACHES...GENERALLY VFR CONDITIONS AT KPDX UNTIL THE
COLD FRONT NEARS LATER TONIGHT. SOME OF THE 30 KT GUSTS MAY EXTEND
WEST FROM KTTD AT TIMES AFFECTING THE TERMINAL TODAY. CIGS WILL
BEGIN TO NOTABLY LOWER LATE THIS EVENING AS THE COLD FRONT
CROSSES. /JBONK
&&

.MARINE...A STRONG FRONTAL SYSTEM WILL GENERATE STORM FORCE WINDS
TODAY. INCREASING SOUTH WINDS WILL BUILD WIND WAVES AND A FRESH SOUTH
SWELL WITH COMBINED SEAS REACHING 20 FT BY SUNRISE ACROSS THE OUTER
WATERS AND CLOSER TO SHORE . SEAS ARE EXPECTED TO BUILD TO 20 TO 24
FT RANGE THIS AFTERNOON. SOUTH WINDS WILL DECREASE LATE TONIGHT AND
BE BELOW 25 KT BY SUNRISE SUNDAY. HAVE CONFIDENCE ANOTHER STRONG WIND
EVENT WILL CROSS THE WATERS SUNDAY NIGHT AND MONDAY. LEANED ON A
BLEND OF THE GFS AND ECMWF SURFACE WINDS AS THE NAM APPEARED TO BE AN
OUTLIER ACROSS THE NORTH. HAVE ISSUED A STORM WATCH FOR THE LATER
HALF OF THE WEEKEND UNTIL FINER DETAILS CAN BE SORTED OUT.

SEAS WILL BRIEFLY DIP BACK INTO THE TEENS SUNDAY BEFORE A LARGE WEST
SWELL BUILDS SUNDAY EVENING. THIS SWELL WILL BRING SEAS BACK ABOVE 20
FT SUNDAY EVENING. MODELS FORECAST THE SWELL TO PEAK AROUND 27 FT AT
18 SECONDS LATE SUNDAY NIGHT. THE LARGE S SWELL COUPLED WITH LARGE
LOCALLY GENERATED WIND WAVES AND FRESH SOUTHERLY SWELL WILL MAKE FOR
CHAOTIC AND DANGEROUS SEAS. ADDITIONALLY...THIS SWELL WILL GENERATE
LARGE AND DANGEROUS BREAKING WAVES IN THE SURF ZONE THROUGH MONDAY
MORNING.

MODELS HAVE BACKED OFF ON TUESDAYS SYSTEM ALTHOUGH GALES STILL SEEM
LIKELY. OVERALL PATTERN WILL RELAX FOR WEDNESDAY AND THURSDAY.
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WARNING FROM 10 AM THIS MORNING TO 2 AM PST SUNDAY
     FOR CENTRAL OREGON COAST-NORTH OREGON COAST.

     HIGH SURF ADVISORY FROM 7 PM SUNDAY TO 9 AM PST MONDAY FOR
     CENTRAL OREGON COAST-NORTH OREGON COAST.

WA...HIGH WIND WARNING FROM 10 AM THIS MORNING TO 2 AM PST SUNDAY
     FOR SOUTH WASHINGTON COAST.

     HIGH SURF ADVISORY FROM 7 PM SUNDAY TO 9 AM PST MONDAY FOR
     SOUTH WASHINGTON COAST.

PZ...STORM WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     STORM WARNING UNTIL 2 AM PST SUNDAY FOR WATERS FROM CAPE
     SHOALWATER WA TO CASCADE HEAD OR FROM 10 TO 60 NM-WATERS
     FROM CASCADE HEAD TO FLORENCE OR FROM 10 TO 60 NM.

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

     SMALL CRAFT ADVISORY FOR WINDS UNTIL 6 AM PST EARLY THIS
     MORNING FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO CASCADE
     HEAD OR OUT 10 NM-COASTAL WATERS FROM CASCADE HEAD TO
     FLORENCE OR OUT 10 NM.

     STORM WARNING UNTIL 2 AM PST SUNDAY FOR COASTAL WATERS FROM
     CAPE SHOALWATER WA TO CASCADE HEAD OR OUT 10 NM-COASTAL WATERS
     FROM CASCADE HEAD TO FLORENCE OR OUT 10 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 AM PST EARLY
     THIS MORNING FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
     CASCADE HEAD OR OUT 10 NM-COASTAL WATERS FROM CASCADE HEAD
     TO FLORENCE OR OUT 10 NM.

&&

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.