High Wind in Oregon, March 5, 2016

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE PORTLAND OR
934 PM PST FRI MAR  4 2016

.SYNOPSIS...A STRONG BUT SLOW MOVING FRONT REMAINS JUST OFF THE
COAST...YIELDING A MOSTLY DRY EVENING FOR THE FORECAST AREA. THIS
FRONT WILL CONTINUE TO SLOWLY MOVE TOWARD THE COAST TONIGHT...
EVENTUALLY SPREADING RAIN ACROSS THE FORECAST AREA LATER TONIGHT AND
SATURDAY MORNING. THE FRONT IS ALSO BRINGING STRONG WINDS TO THE
COASTAL WATERS...WHICH WILL BRIEFLY IMPACT THE IMMEDIATE COAST LATER
TONIGHT. A STRONGER LOW PRESSURE SYSTEM IS EXPECTED TO DEVELOP
OFFSHORE SATURDAY...BRINGING MORE RAIN AND GUSTY WINDS BY SATURDAY
EVENING. COOLER AIR BEHIND THIS SYSTEM WILL CAUSE SNOW LEVELS TO
LOWER TO THE CASCADE PASSES FOR A FEW INCHES OF ACCUMULATION BY
SUNDAY MORNING. SHOWERS CONTINUE SUNDAY AND MONDAY WITH POSSIBLY AN
AFTERNOON THUNDERSTORM OR TWO. ADDITIONAL WET WEATHER WILL LIKELY
ARRIVE TOWARDS THE MIDDLE TO LATTER HALF OF NEXT WEEK.

&&

.SHORT TERM...TONIGHT THROUGH MONDAY...WINDS REMAIN GENERALLY LIGHT
ALONG THE COAST SO FAR THIS EVENING...A STARK CONTRAST FROM THE GALE
FORCE WINDS OCCURRING JUST OFFSHORE. THE DELAY IN WINDS HAS LARGELY
BEEN DUE TO THE DEVELOPMENT OF A WEAK WAVE OF LOW PRESSURE NEAR
40N/127W WHICH IS KEEPING PRESSURE GRADIENTS UNFAVORABLE FOR STRONG
WINDS ALONG THE COAST. THIS WAVE OF LOW PRESSURE IS BECOMING
ABSORBED INTO THE FRONT...WITH THE REMNANT IMPULSE FORECAST BY THE
00Z NAM AND UW WRF-GFS TO LIFT NORTH ALONG THE OREGON COAST
OVERNIGHT TONIGHT. THIS COULD YIELD A BRIEF PERIOD WHERE WINDS REACH
55-65 MPH ALONG THE BEACHES AND HEADLANDS...WHILE THE COASTAL
COMMUNITIES SEE MUCH LIGHTER WINDS. REGARDLESS...CONFIDENCE IS
DWINDLING A BIT ON WHETHER OR NOT THE HIGH WIND WARNING WILL VERIFY
TONIGHT. HOWEVER CONFIDENCE THAT IT WILL NOT VERIFY IS NOT NEARLY
HIGH ENOUGH TO CANCEL AN EXISTING WARNING AT THIS POINT.

THE SAME WAVE OF LOW PRESSURE HOLDING UP THE WINDS ALONG THE COAST
HAS ALSO ALLOWED A MAINLY DRY EVENING ACROSS THE FORECAST AREA ASIDE
FROM SOME SPRINKLES HERE AND THERE. IN FACT...NO RAWS OR ASOS
STATIONS HAVE REPORTED MEASURABLE PRECIPITATION IN THE PAST HOUR IN
OUR CWA. ISSUED A QUICK UPDATE EARLIER TO DECREASE POPS EAST OF THE
COAST RANGE THIS EVENING. 03Z HRRR AND 00Z NAM/GFS STILL SUGGEST THE
FRONT WILL MAKE ENOUGH PROGRESS TOWARD THE COAST TO SPREAD RAIN
INLAND LATER TONIGHT AND SAT MORNING. THE EXISTING FRONT WILL LIKELY
STRETCH AND WEAKEN CONSIDERABLY WHILE OVER WESTERN WA/OR SAT.

THE FRONT WILL LIKELY LEAVE BEHIND PLENTY OF LOW-LEVEL MOISTURE...
AND THERE MAY BE ENOUGH SUN BREAKS OR THINNING IN CLOUD COVER TO
ALLOW SFC TEMPS TO REACH A POINT WHERE THE AIR MASS WILL BE
CONDITIONALLY UNSTABLE UP TO 25 KFT OR SO. WITH STRONG FORCING
EXPECTED TO ARRIVE IN THE FORM OF A DEVELOPING LOW AND NEGATIVELY-
TILTED COLD FRONT...DECIDED IT WOULD BE PRUDENT TO ADD A THUNDER
MENTION TO THE ENTIRE CWA SAT AFTERNOON AND EVENING. ALSO ADJUSTED
TEMPS UPWARDS BY A FEW DEGREES AS THE 00Z GFS SHOWS A THERMAL RIDGE
OF 850 MB TEMPS +8 TO +10 DEG C SPREADING UP NORTH THROUGH THE
WILLAMETTE VALLEY SAT AFTERNOON. BARRING A COMPLETELY CLOUDY DAY WITH
NO SUNBREAKS AT ALL...THIS SHOULD ALLOW MOST LOWLAND LOCATIONS TO
REACH 60 DEGREES SAT AFTERNOON. AS MENTIONED ABOVE...THESE WARMER SFC
TEMPS WILL ASSIST ANY SFC-BASED CONVECTION THAT TRIES TO DEVELOP
ALONG/AHEAD OF THE COLD FRONT COMING IN FROM THE SOUTHWEST.

THE DEVELOPING LOW MENTIONED ABOVE IS SHOWING MORE AND MORE
INDICATION THAT IT IS GOING TO BE THE BIG DOG OF THIS SERIES OF LOWS
BRUSHING THE PAC NW COAST. A VERY WELL-DEFINED NORTHERN STREAM
SHORTWAVE IS EASILY VISIBLE ON WATER VAPOR SATELLITE IMAGERY NEAR
40N/145W. A STRONG PUSH OF COLD AIR BEHIND THIS SYSTEM IS TIGHTENING
THE BAROCLINICITY...WHILE A 160-180 KT JET STREAM FEEDS INTO THIS
SYSTEM. ALL THE INGREDIENTS ARE THERE FOR RAPID CYCLOGENESIS...AND
THE 00Z GFS SHOWS THIS NICELY IN DEVELOPING A 975 MB LOW NEAR
45N/130W BY SAT AFTERNOON WHICH EVENTUALLY BECOMES A 965 MB PARENT
LOW NEAR HAIDA GWAII BY SUN AFTERNOON. MEANWHILE...COLD AIR WILL
CONTINUE TO UNDERCUT THE LOW...DRIVING A STRONG AND VERY SHARP COLD
FRONT INTO THE OREGON COAST LATE SAT AFTERNOON OR SAT EVENING. THE
00Z NAM DEVELOPS ANOTHER SUB-980 MB LOW ALONG THE FRONT NEAR THE
OREGON COAST...WHICH IS POSSIBLE BUT THE DETAILS ARE LIKELY
IMPOSSIBLE FOR THE MODEL TO RESOLVE AT THIS POINT. EITHER
WAY...STRONG COLD ADVECTION FROM THE SOUTHWEST AND PRESSURE RISES
BEHIND THE FRONT ARE LOOKING INCREASINGLY FAVORABLE FOR WINDY
CONDITIONS NOT JUST ALONG THE COAST...BUT INLAND AS WELL SAT EVENING.
WOULD NOT BE SURPRISED IF WE END UP WITH LOW-END ADVISORY GUSTS IN
THE WILLAMETTE VALLEY... THOUGH THIS IS NOT SHOWN AT THIS POINT BY
EITHER THE 00Z NAM OR UW WRF. WILL HOLD GUSTS JUST BELOW ADVISORY
CRITERIA FOR NOW...WITH 30-40 MPH GUSTS IN THE WILLAMETTE VALLEY.

THE HIGH WIND WATCH FOR THE COAST SATURDAY NIGHT STILL LOOKS GOOD.
GIVEN THE TRAJECTORY OF THE LOW...GRADIENTS WILL PROBABLY NOT BE
FAVORABLE FOR STRONG WINDS UNTIL THE FRONT ARRIVES. HOWEVER A STRONG
SURGE OF WIND IS LIKELY ALONG AND AHEAD OF THE FRONT...NOT JUST FOR
THE BEACHES AND HEADLANDS BUT FOR THE COASTAL COMMUNITIES AS WELL.
JUST HOW STRONG WILL DEPEND LARGELY ON THE TRACK OF THE PARENT LOW
AND IF/WHEN/WHERE ANY SECONDARY LOWS DEVELOP. GIVEN THE COLD AIR
PUSHING IN BEHIND THE FRONT...THIS APPEARS TO BE THE TYPE OF EVENT
WHICH UNDERPERFORMS FOR THE BEACHES AND HEADLANDS BUT OVERPERFORMS
ELSEWHERE.

SNOW LEVELS WILL LOWER DRAMATICALLY IN THE COLD AIR BEHIND THE FRONT
SAT NIGHT/SUN. MEANWHILE COLD AIR ALOFT WILL KEEP THE AIR MASS
UNSTABLE WITH COOL SHOWERS AND ISOLATED THUNDERSTORMS LINGERING
THROUGH MONDAY. A FEW INCHES OF SNOW WILL LIKELY ADD UP IN THE
CASCADES BY MONDAY. SOME MODELS HINT AT THE POTENTIAL FOR YET
ANOTHER LOW TO DEVELOP TO OUR SOUTHWEST SUN NIGHT...BUT GIVEN THE
MAGNITUDE OF COLD ADVECTION BEHIND SAT EVENINGS FRONT...IT APPEARS
ANY STRONG LOW THAT WOULD DEVELOP BY THEN WOULD LIKELY STAY WELL TO
OUR SOUTH. ALL IN ALL...AN INTERESTING PATTERN FOR STORMWATCHERS THE
NEXT SEVERAL DAYS.  WEAGLE

.LONG TERM...MONDAY NIGHT THROUGH FRIDAY...AN UPPER LEVEL TROUGH AND
ONSHORE FLOW WILL CONTINUE SHOWERS MONDAY NIGHT. TUESDAY MORNING
WILL BE BETWEEN SYSTEMS WITH SHOWERS RAPIDLY DECREASING UNDER BRIEF
RIDGING. THE NEXT PACIFIC FRONT WILL BRING A RETURN OF RAIN AND
MOUNTAIN SNOW TUESDAY AFTERNOON WITH SNOW LEVELS AROUND 3500 FEET.
THERE IS POTENTIAL FOR AN ATMOSPHERIC RIVER EVENT WEDNESDAY AND
THURSDAY WITH A SURFACE LOW (AND ASSOCIATED FRONT) TAPPING INTO A
SWATH OF 1.10 TO 1.4 INCHES OF PRECIPITABLE WATER. INTEGRATIVE VAPOR
TRANSPORT SHOWS THE BEST CHANCE FOR HEAVY RAIN ACROSS SW
OREGON...BUT THINK NW OREGON AND SW WASHINGTON CAN STILL GET A
DECENT SOAKING. SNOW LEVELS WILL INITIALLY START AROUND 3500 FEET
TUESDAY NIGHT...THEN RAPIDLY RISE TO AROUND 5500 FEET WEDNESDAY. TJ

&&

.AVIATION...A FRONT AND BAND OF RAIN WILL PUSH ONSHORE OVERNIGHT
AND BRING A DETERIORATION TO MVFR FLIGHT CONDITIONS TO MANY TAF
SITES BETWEEN 06Z AND 12Z MONDAY. INCREASING OFFSHORE FLOW SHOULD
TURN CONDITIONS PREDOMINANTLY VFR AREA WIDE AFTER 12Z SATURDAY.
ANOTHER LOW PRESSURE SYSTEM THAT WILL LIKELY BRING STRONGER WINDS
REGION WIDE SATURDAY EVENING WITH GUSTS UP TO 50 KT POSSIBLE ALONG
THE COAST AND 35 KT ACROSS THE INTERIOR. THIS SYSTEM WILL ALSO
LIKELY PRODUCE A PERIOD OF FLIGHT RESTRICTIONS FOR COASTAL
LOCATIONS BETWEEN 00Z AND 06Z SUNDAY.

KPDX AND APPROACHES...EXPECT PREDOMINATELY VFR CONDITIONS THROUGH
06Z SUNDAY AS A SERIES OF LOW PRESSURE SYSTEMS KEEP EAST TO SOUTH
WINDS ELEVATED. HOWEVER...A PERIOD OF STEADIER RAIN LATER TONIGHT
SHOULD BE ENOUGH TO PRODUCE A BRIEF PERIOD OF MVFR CONDITIONS...MOST
LIKELY BETWEEN 09Z AND 12Z SATURDAY. /NEUMAN

&&

.MARINE...SEVERAL SURFACE LOW PRESSURE SYSTEMS DEVELOPED THIS
AFTERNOON AND ARE MOVING NORTHEASTWARD TOWARDS THE PACIFIC
NORTHWEST. WHILE EACH STORM SYSTEM IS NOTABLE...THIS HAS LIKELY
PREVENTED A WORST CASE SCENARIO FROM UNFOLDING. NONETHELESS...GALE
FORCE WIND GUSTS ARE CURRENTLY BEING OBSERVED ACROSS THE
WATERS...AND EXPECT THESE TO CONTINUE FOR THE NEXT SEVERAL HOURS
BEFORE WEAKENING AFTER MIDNIGHT. WILL KEEP THE CURRENT STORM
WARNING GOING DUE TO AN INHERENT UNCERTAINTY WITH THIS TYPE OF
SYSTEM...BUT LATEST TRENDS IN OBSERVATIONS AND MODEL GUIDANCE ARE
NOT PROMISING.

EXPECT WINDS AND SEAS TO SUBSIDE AFTER MIDNIGHT WITH SEAS LIKELY
DROPPING INTO THE LOW TO MID TEENS SATURDAY MORNING THROUGH AT
LEAST EARLY SATURDAY AFTERNOON. HOWEVER...THE LULL IN WINDS AND
SEAS WILL BE SHORT LIVED AS THE NEXT STORM SYSTEM PRODUCES ANOTHER
SET OF STRENGTHENING SURFACE LOW PRESSURES AND STRONGER WINDS AND
HIGH SEAS ACROSS THE WATERS. THERE IS CERTAINLY POTENTIAL FOR
STORM FORCE GUSTS...BUT SUSPECT WIND GUSTS WILL GENERALLY REMAIN
IN SOLID GALE FORCE CRITERIA OF 40 TO 45 KT. AT THIS POINT...THE
STRONGEST WINDS AND ABRUPT RISE IN SEAS WILL LIKELY BEGIN ACROSS
THE CENTRAL OREGON WATERS BETWEEN 3 PM AND 6 PM AND BETWEEN 6 PM
AND 9 PM ACROSS THE NORTHERN WATERS.

WINDS AND SEAS WILL LIKELY REMAIN ELEVATED THROUGH SUNDAY WITH A
SMALL CHANCE THAT ANOTHER SURFACE LOW PRESSURE COULD IMPACT THE
REGION. HOWEVER...IT APPEARS THIS SYSTEM WILL MOST LIKELY STAY
SOUTH OF THE REGION SUNDAY AFTERNOON/EVENING.

ANOTHER FRONT TUESDAY-ISH HAS THE POTENTIAL TO BRING ANOTHER ROUND
OF GALE FORCE WINDS...WITH PERHAPS A STRONGER STORM SYSTEM
WEDNESDAY. SEAS LOOK TO REMAIN ABOVE 10 FT FOR AT LEAST THE NEXT
WEEK...AND MAY EXCEED 20 FT BY QUITE A BIT TOWARDS THE MIDDLE OF
NEXT WEEK. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WARNING UNTIL 4 AM PST SATURDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

     HIGH SURF ADVISORY UNTIL 3 AM PST SATURDAY FOR CENTRAL OREGON
     COAST-NORTH OREGON COAST.

     HIGH WIND WATCH FROM SATURDAY AFTERNOON THROUGH LATE SATURDAY
     NIGHT FOR CENTRAL OREGON COAST-NORTH OREGON COAST.

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

     HIGH SURF ADVISORY UNTIL 3 AM PST SATURDAY FOR SOUTH WASHINGTON
     COAST.

     HIGH WIND WATCH FROM SATURDAY AFTERNOON THROUGH LATE SATURDAY
     NIGHT FOR SOUTH WASHINGTON COAST.

PZ...GALE WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY MORNING FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD OR OUT
     60 NM.

     STORM WARNING UNTIL 1 AM PST SATURDAY FOR COASTAL WATERS FROM
     CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     STORM WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY EVENING
     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 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.