High Wind in Washington, November 12, 2016

Area Forecast Discussion
National Weather Service Portland Oregon
257 AM PST Sat Nov 12 2016

.SYNOPSIS...showery today, as low pressure moves into western
Washington. But drying tonight as region awaits the next front. After
morning fog, rain will increase during the day on Sunday. Rain will
continue into Monday, with possibly heavy rain at times. Wet weather
will continue through the week, though snow levels will fall to or
below the major passes in the Cascades by Wed afternoon.
&&

.Short Term (Today through Monday)...Cold front now pushing up and
over the Cascades. Rain has now transitioned to showers. The showers
across the region will gradually decrease as today progresses. Main
driver for the showers will be the unstable air mass associated with
the upper low that is just off the Oregon coast this am. This low
will drift northeastward and track into Washington later this am.
Still just enough instability with the low that could see an
isolated thunderstorm over the coastal waters and onshore, but will
limit the threat only to the those areas and possibly into the
coastal mountains this am.

Now, other problem is the gust winds with the gradient that lies on
the south side of the low. This tighter gradient will push onshore
this am, but will be gradually weakening. Still, gradient tight
enough to produce gusty winds along the coast. Will maintain the High
Wind Warning for the open beaches and headlands through 8 am today,
with peak gusts 50 to 60 mph likely, and 35 to 45 mph further inland.
Winds will quickly ease this am as then low heads inland.

Region will be between systems tonight into early Sunday. Think high
clouds mainly across region. With light winds tonight, will see areas
of low clouds and fog forming, especially to south of Portland. Next
system approaching on Sunday will spread rain back across the coast
in the morning, and inland in the afternoon and evening. This next
front will be a slow moving system, and with decent warm advection,
there is potential for heavy rain at times later Sunday night into
Monday am for coastal/coast ranges extending across the interior to
the north Oregon and south Washington Cascades. Not expecting any
flooding on rivers, but would expect to see considerable ponding of
water, mainly with leaf-clogged storm drains and other poor drainage
areas.	Rain will continue on Monday, though will start to ease back
somewhat later in the afternoon.

At moment, rainfall for late Sunday through Monday looks to be
generally 1 to 2 inches along the coast, with 2 to 3 inches for the
Coast Range/Willapa Hills. Similar values expected in the Cascades,
with 1 to 3 inches though heaviest rainfall will be over the south
Washington Cascades. Rainfall bit less for interior valleys, with
0.75 to 1.25 inch looking reasonable.		       Rockey.

&&

.AVIATION...A cold front is approaching the coast early this
morning, bringing rain and gusty southerly winds. Conditions are
currently predominantly MVFR at the coast, and VFR over the
interior. Expect MVFR to become more prevalent over the interior
between 12Z-15Z as the front moves onshore. The front will be
through by 18Z, with post-frontal showers continuing through the
afternoon. Expect mainly VFR conditions behind the front, with
occasional MVFR in heavier showers. Clearing skies tonight to set
the stage for another round of IFR fog and low clouds.

Expect southerly winds gusting 35-40 kt for the coastal TAF sites
early this morning. Winds will become breezy for the interior TAF
sites as well after 12Z, with gusts 20 to 25 kt possible.

KPDX AND APPROACHES...VFR to prevail until around 12Z. Conditions
expected to drop into MVFR around 12Z with frontal passage.
Improvement to VFR mid to late morning, but the usual brief
periods of post-frontal MVFR in heavier showers late Sat morning
through the evening. Skies clearing this evening may allow for IFR
fog to form overnight into Sun morning. Pyle

&&

.MARINE...A surface low pres system is moving onto Vancouver
Island this morning. An associated cold front is moving through
the Washington and Oregon coastal waters, bringing solid gale
force winds gusting 35 to 40 kt. A coastal jet may bring localized
gusts to 45 kt within 30 nm of the coast between 3-6 AM. Winds
will subside fairly rapidly and turn to the W-SW later this
morning and this afternoon after the cold front has pushed
onshore. Winds to be below 20 kt by early afternoon.

Another strong frontal system will arrive late Sun from the NW and
push slowly through the waters Sun night and Mon morning. Gale
force winds are likely, especially over the northern waters. There
will be a period of more benign winds during the middle of next
week as a showery upper level low moves over the region. Then
another front looks to be on tap for the end of the week.

Seas have increased into the mid teens this morning, with a
dominant longer period westerly swell. Expect seas will peak
around 15 to 17 ft early this morning, then gradually subside
later this morning and this afternoon. Expect seas down around 12
ft by this evening, then drop below 10 ft late tonight or Sun
morning. The late Sun/Mon front will push seas back into the mid
teens again. Pyle

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning until 8 am today for the North and Central
	 Coast of Oregon.

WA...High Wind Warning until 8 am today for South Wash. Coast.

PZ...Gale Warning early this am on all coastal waters.

     Small Craft Advisory for Rough Columbia River Bar until 7 PM
     PST this evening, and for late tonight.

&&

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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.