High Wind in Washington, February 11 to 12, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
915 PM PST TUE FEB 11 2014

.SYNOPSIS...A PACIFIC STORM WILL PRODUCE HEAVY RAIN AND STRONG WINDS
ACROSS THE REGION TONIGHT THROUGH WEDNESDAY MORNING...ESPECIALLY FOR
THE COAST AND COAST RANGE. WESTERLY FLOW ACROSS THE PACIFIC WILL
CONTINUE WARMER AND MOISTER WEATHER THIS WEEK. ANOTHER STORM IS
EXPECTED FRIDAY.

&&

.SHORT TERM UPDATE...FORECAST IS ON TRACK AND MADE ONLY MINOR CHANGES
WITH THE EVENING UPDATE. THE SURFACE LOW HAS MOVED QUICKLY TOWARDS THE
COAST THIS EVENING AND IS CURRENTLY AROUND 100 MILES OFF THE COAST
FROM SEATTLE WASHINGTON. THE SURFACE PRESSURE GRADIENT IS TIGHTENING
OFFSHORE AND ALONG THE COAST AND WINDS HAVE BEEN GRADUALLY
INCREASING. THERE HAVE BEEN A FEW GUSTS CLOSE TO 50 MPH ALONG THE
SOUTH WASHINGTON AND NORTHERN OREGON COAST THE PAST COUPLE OF HOURS.
THE GRADIENT WILL CONTINUE TO TIGHTEN AS THE LOW CONTINUES TO MOVE
INLAND WITH STRONG GUSTY WINDS THROUGH THE NIGHT...GRADUALLY MOVING
INLAND. THE MEDFORD TO ASTORIA GRADIENT IS CURRENTLY 11 MB...AND
SHOULD STRENGTHEN TO AROUND 16 MB AROUND MIDNIGHT TONIGHT.

BESIDES THE WIND...THE PORTLAND FORECAST AREA HAS BEEN GETTING MUCH
NEEDED RAIN. THE RAIN HAS BEEN RATHER EARNEST AND RAINFALL TOTALS
ACROSS THE NORTHWEST HAVE BEEN AROUND 0.1 TO 0.2 INCH HIGHER THAN
WHAT WAS FORECASTED. THE NORTH OREGON COAST RANGE AND THE WILLAPA
HILLS OF SW WASHINGTON HAVE MEASURED AROUND 0.6 INCH SINCE 5
PM...WITH THE CENTRAL AND NORTHERN WILLAMETTE VALLEY AROUND 0.25
INCH. HAVE ADJUSTED TONIGHT'S QPF UP A TAD TO ACCOUNT FOR THE HIGHER
RAINFALL TOTALS.				                        HARTLEY

PREVIOUS SHORT TERM DISCUSSION...TONIGHT THROUGH FRIDAY...LITTLE
CHANGE IN THE OVERALL PATTERN NOR THE MUCH IN THE DETAILS OVER THE
NEXT FEW DAYS. MAIN STORY FOR TONIGHT WILL BE THE STRONG WINDS
EXPECTED ALONG THE COAST AND COAST RANGE THIS EVENING AND OVERNIGHT.
STRONG STABLE FORCING WILL CREATE A SIGNIFICANT COASTAL JET. THE
SURFACE LOW IS COHESIVELY MODELED BY THE NAM...GFS...AND THE ECMWF TO
BRING THE SURFACE LOW CENTER ONSHORE AROUND THE STRAIT OF JUAN DE
FUCA AROUND MIDNIGHT TONIGHT. THERE HAS BEEN VERY LITTLE CHANGE IN
MODELED WINDS WITH 925 MB WINDS IN PARTICULAR SHOWING SPEEDS AROUND
70 KTS/80 MPH. THE DIRECTION IS SOMEWHAT MORE WESTERLY AGAINST THE
SURFACE GRADIENT BUT NOT ENOUGH TO PRECLUDE SOME 75 MPH
BEACH/HEADLAND GUSTS. THE COASTAL COMMUNITIES AND THE COAST RANGE
WILL ALSO FEEL THE BRUNT TO A LESSER EXTENT. ALSO ADDED THE ENTIRE
VALLEY	I-5 CORRIDOR AS THE LOW TRACK WILL BRING A SOLID PARALLEL
GRADIENT AND GUSTY WIND POTENTIAL. SPEEDS ARE A LITTLE IFFY, BUT AM
BANKING ON ADDITIONAL TREE WEAKENING FROM THE RECENT ICE STORMS AND
ALSO SOME MODERATE SOIL SATURATION TO RESULT IN LIMBS COMING OFF OR
THE OCCASIONAL UPROOTING.

THE ASSOCIATED BURST OF MOISTURE FROM THIS SYSTEM WILL BRING A BURST
OF HEAVY RAIN AND HIGH ELEVATION SNOW. WE FULLY EXPECT TO SEE SOME
SHARP RISES FROM THE REMAINDER OF THE SNOW MELT BUT MORE LIKELY FROM
THE OVERALL RAINFALL. THIS ROUND OF RAIN WILL LIKELY TAKE CARE OF
THE REST OF THE LOW LAND SNOW PACK IN THE SOUTH WILLAMETTE VALLEY.
WHILE THERE MAY BE SOME SMALLER TRIBS AND CREEKS RUNNING AT ELEVATED
STAGES NOT SEEN SINCE LATE LAST FALL, THIS ROUND OF RAIN IS UNLIKELY
TO BRING ANY OF THEM OUT OF THEIR BANKS. SNOW LEVELS WILL CONTINUE
RISING TONIGHT UNTIL THE COLD FRONT CROSSES LATE OVERNIGHT. THIS
WILL KEEP NOTABLE SNOW ACCUMULATIONS ABOVE 5000 FEET IN THE
WASHINGTON CASCADES AND MAINLY ABOVE 6000 FEET TO THE SOUTH. ALL
TOLD...PORTIONS OF THE CASCADES WILL GET AROUND 2 INCHES OF LIQUID
EQUIVALENT.

PRECIP WILL BECOME MORE HYBRID STRATIFORM/SHOWERY WED MORNING AS A
BREAK IN THE WINDS WILL SIGNAL A SHORT BREAK IN THE WIND FLOW
PATTERN. THIS WILL SIGNIFICANTLY EASE PRECIP RATES UNTIL THURSDAY
AFTERNOON/EVENING WHEN THE NEXT MOISTURE WAVE PUSHED ONSHORE. THIS
SYSTEM HAS WIND AND MOISTURE SIGNATURES MORE RESEMBLING AN
ATMOSPHERIC RIVER AND WILL PRESENT A 1-2 PUNCH FRIDAY AND SATURDAY.
THE FIRST WAVE OF THIS EVENT WILL BRING ANOTHER 2 TO 3 INCHES OF
LIQUID MAINLY TO TOWARD THE LANE CASCADES AT THIS TIME. THE BULK OF
THE MOISTURE WILL BE SHUNTED INTO SW OREGON/NW CALIFORNIA BUT WE
WANT TO EMPHASIZE, HOWEVER, SUBTLE SHIFTS IN NORTH/SOUTH POSITION
OFTEN OCCUR IN THE FOCUS POINT OF THE NARROW AND HEAVIEST PRECIP
BAND. AS CURRENTLY FORECAST, THE AMOUNT OF RAIN EXPECTED BEGINNING
WITH THIS EVENT HAS THE BEST POTENTIAL TO SEND SOME OF THE MAIN STEM
TRIBUTARIES OUT OF THEIR BANKS. FORTUNATELY...THE MAIN STEM RIVERS
WILL SEE NOTABLE RISES BUT STILL APPEAR TO STAY BELOW FLOOD STAGE AS
AREA RESERVOIRS CONTINUE TO HAVE ABUNDANT FLOOD CONTROL CAPACITY.
							                                /JBONK

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS... FRIDAY NIGHT
THROUGH TUESDAY...PROGRESSIVE FLOW WILL CONTINUE THROUGH EARLY NEXT
WEEK. MODEL AGREEMENT IS MUCH HIGHER THAN AVERAGE WHICH LENDS
CONFIDENCE TO THE FORECAST. THE POLAR VORTEX /AREA OF LOWEST 500 MB
HEIGHT/ THAT HAS BEEN STUBBORNLY HANGING OUT OVER CENTRAL AND EASTERN
CANADA FOR MUCH OF THIS SEASON WILL SHIFT NORTH AND THEN REFORM
FARTHER WEST...BRIEFLY TAKING UP RESIDENCE OVER ALASKA. THIS LARGE
UPPER LOW WILL USHER AT LEAST TWO SHARP SHORT WAVES AND ASSOCIATED
COLD FRONTS INTO THE PAC NW DURING THE EXTENDED PERIOD. THE FIRST
FRONT LOOKS TO ARRIVE SATURDAY OR SATURDAY NIGHT. THIS FRONT WILL TAP
INTO TROPICAL MOISTURE/REMNANT ATMOSPHERIC RIVER...AND MODELS AGREE
THAT HEAVY RAIN IS LIKELY SATURDAY. IN ADDITION...IF MODELS MAINTAIN
THEIR CURRENT DEPICTION OF STRONG WARM ADVECTION WITH HIGH DEWPOINTS
AHEAD OF THE FRONT AND A SHARP TEMPERATURE GRADIENT BEHIND
IT...CANNOT RULE OUT THE CHANCE FOR THUNDER ESPECIALLY WITH THE
FRONTAL PASSAGE SOMETIME SATURDAY AFTERNOON OR EVENING. THERE IS NOT
ENOUGH OF A SIGNAL TO ADD THIS TO
THE CURRENT FORECAST...HOWEVER IT DOES AT LEAST BEAR A MENTION HERE.
SUNDAY INTO MONDAY MODELS CONTINUE RATHER REMARKABLE AGREEMENT AND
ARE DEPICTING A STATIONARY FRONT SETTING UP OVER SOUTHWESTERN
WASHINGTON/NORTHWEST OREGON. THIS WOULD FOCUS ANOTHER ROUND OF HEAVY
PRECIPITATION ON THE PAC NW...BEFORE ANOTHER STRONG COLD FRONT IS
PUSHED THROUGH THE REGION TUESDAY AS THE AFOREMENTIONED UPPER LOW
OVER ALASKA BEGINS TO FILL/WEAKEN AND SLIDE SOUTHWARD.	 BURGESS

&&

.AVIATION...SOME IMPROVEMENT THIS EVENING AS INCREASING SOUTHERLY
FLOW BROUGHT MIXING TO THE LOWER LAYERS. GENERALLY MVFR AT THE
COAST AND NORTH INTERIOR...WITH MORE VFR INLAND SOUTH.
INLAND TAF SITES SHOULD REMAIN IN THE HIGH-MVFR TO LOW-VFR
PATTERN THROUGH THIS EVENING THEN BECOME PRIMARILY MVFR. GOOD
CHANCE INLAND SITES WILL GO BACK TO VFR MID TO LATE WED MORNING.
MODELS SHOW ANOTHER WAVE MOVING INTO SWRN OREGON EARLY WED
AFTERNOON THAT COULD BRING MVFR OR LOWER CONDITIONS TO THE S PART
OF THE FORECAST AREA. COASTAL AREAS LIKELY TO REMAIN MVFR TO IFR
IN VIS AND CIGS THROUGH WED.

WIND...GUSTS 50-65 KT LIKELY ALONG THE COAST THIS EVENING AND
TONIGHT...THEN DROPPING OFF QUICKLY WED MORNING. INTERIOR VALLEY
AREAS WILL SEE GUSTS UP TO 40 KT. MAIN CONCERN WILL BE SUBSTANTIAL
SPEED SHEAR 06Z-12Z WED. WILL CONTINUE LLWS FOR ALL INLAND TAF
SITES AS MODELS SHOW SFC WIND SPEEDS 15-25 KT BUT 45-60 KT FROM
1500 TO 3000 FT.

KPDX AND APPROACHES...A MIX OF MVFR AND LOW-END VFR THROUGH THE
NIGHT. E-SE WIND WILL SWITCH TO THE SOUTH AND INCREASE TONIGHT.
FAIRLY SUBSTANTIAL SPEED SHEAR IN THE LOWEST 2000 FEET 06Z-12Z
WED...WITH 15-25 KT AT THE SURFACE AND 45-55 KT AT 2000 FT.
						                             WEISHAAR/MH

&&

.MARINE...FORECAST IN PRETTY GOOD SHAPE STRONG GALES IN THE INNER
WATERS AS A COASTAL JET SETS UP. WINDS NOT QUITE UP TO GALES NEAR
THE 60 NM AREA BUT SHOULD BE INCREASING SHORTLY. MODELS STILL
PUSHING 40-50 KT BOUNDARY LAYER WIND SPEEDS WITH 55-60 KT AT 975
MB. ESTIMATE PEAK WINDS BETWEEN 11 PM AND 2 AM...THEN WIND SPEEDS
DROP OFF RATHER QUICKLY BEHIND THE COLD FRONT. IN THESE
SITUATIONS...A COASTAL BARRIER JET IS QUITE COMMON.

ANOTHER IMPULSE MOVES BY TO THE NORTH LATE WED AND WED EVENING
WHICH COULD PRODUCE NEAR-GALE FORCE GUSTS. A SECOND FAIRLY POTENT
SYSTEM MOVES THROUGH THU NIGHT WHICH LOOKS TO GIVE STRONG GALE
FORCE WIND TO THE WATERS. ADDITIONAL SYSTEMS IMPACTS THE WATERS
THIS WEEKEND...WITH STORM FORCE GUSTS POSSIBLE.

SEAS SHOULD BE IN THE 15 TO 18 FT TONIGHT WITH STORM FORCE WINDS.
THERE WILL BE A CONSIDERABLE WIND-WAVE COMPONENT TO THE
SEAS...POSSIBLY UP TO 15 FT. SEAS REMAIN FAIRLY ACTIVE THE REST OF
THE WEEK...POSSIBLY REACHING CLOSE TO 20 FT OVER THE WEEKEND.
						                               WEISHAAR/MH

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WIND ADVISORY UNTIL 6 AM PST WEDNESDAY FOR CENTRAL WILLAMETTE
     VALLEY-GREATER PORTLAND METRO AREA-LOWER COLUMBIA-SOUTH
     WILLAMETTE VALLEY.

     HIGH WIND WARNING UNTIL 6 AM PST WEDNESDAY FOR CENTRAL COAST
     RANGE OF WESTERN OREGON-COAST RANGE OF NORTHWEST OREGON.

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

WA...WINTER STORM WARNING UNTIL 6 AM PST WEDNESDAY FOR SOUTH
     WASHINGTON CASCADES.

     WIND ADVISORY UNTIL 6 AM PST WEDNESDAY FOR GREATER VANCOUVER
     AREA-I-5 CORRIDOR IN COWLITZ COUNTY.

     HIGH WIND WARNING UNTIL 6 AM PST WEDNESDAY FOR WILLAPA HILLS.

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

PZ...STORM WARNING UNTIL 6 AM PST WEDNESDAY FOR COASTAL WATERS FROM
     CAPE SHOALWATER WA TO CASCADE HEAD OR OUT 60 NM.

     STORM WARNING UNTIL 4 AM PST WEDNESDAY FOR COASTAL WATERS FROM
     CASCADE HEAD OR TO FLORENCE OR OUT 60 NM.

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

&&

MORE WEATHER INFORMATION ONLINE AT..
    HTTP://WEATHER.GOV/PORTLAND

INTERACT WITH US VIA SOCIAL MEDIA
    WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
    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.