Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 192204

Area Forecast Discussion
National Weather Service Portland OR
204 PM PST Sun Nov 19 2017

.SYNOPSIS...The upcoming week looks unsettled and wet. A cold front
will slowly move onto the north coastal areas this afternoon and
through the remainder of southwest Washington and northwest Oregon
tonight and Monday, stalling and weakening over the southern part of
the forecast area Monday afternoon. The front then lifts back north
across the forecast area as a warm front Monday night and Tuesday.
The front will linger over the area into Wednesday. Another cold
front will move through on Thanksgiving with showers lingering into
Friday but decreasing later in the day. The next system is expected
Saturday night and Sunday.

.SHORT TERM...Tonight through Wednesday...The next front is now
spreading rain onto the Washington coast this afternoon and will
spread onto our northern coastal forecast zones and into the the
adjacent coastal mountains during the remainder of this afternoon,
and probably not much farther inland until this evening. The front
will slowly sag south through southwest Washington and northwest
Oregon tonight and Monday, briefly weakening and lingering in the
south part of our forecast area Monday afternoon.

There will be decent winds along the coast and in the coastal
mountains this afternoon and tonight ahead of the front, with the
strongest winds along the coastal headlands and beaches and over the
higher terrain of the coast range. It will also be breezy in the
inland valleys this afternoon and tonight, with gusts 30 to 35 mph

There is some residual cold air in the south Washington Cascades, and
will continue the Winter Storm Warning there for tonight. Snow levels
will be rising across the Oregon Cascades through today and tonight,
finally reaching the south Washington Cascades Monday morning.

The leftover front across the southern part of our forecast area
Monday afternoon continues to be forecast to lift north across the
forecast area Monday night and Tuesday for more rain. We will likely
see some east wind develop through the Gorge and in the Portland and
Vancouver metro areas Monday night and Tuesday as the main low with
this warm front will be developing offshore and a bit outside 130W.
Snow levels will remain rather high in the Cascades as well.

At this point, south of this warm front another frontal boundary
extends southwestward and there is a wave that moves north along this
boundary near our coast Tuesday night into Wednesday that keeps some
rain going on.

Total rainfall amounts through Tuesday could reach 3-5 inches at the
coast and in the Cascades, and 0.50-1.5 inches in the valleys. Totals
through Wednesday could reach 4-7 inches at the coast and the
mountains and 0.67-1.75 in the valleys. The rainfall is not expected
to cause flooding other than some possible localized urban flooding
should leaves clog storm drains, though area rivers and streams will
likely see some sharp rises this week. Tolleson

.LONG TERM...Wednesday night through Sunday. Expect steady rain
across the region during any pre-holiday travel. For Thanksgiving, a
front crossing the area will bring rain to southwest Washington and
northwest Oregon, but expect temperatures to be several degrees above
seasonal normals, with afternoon highs in the mid to upper 50s. Snow
levels look to remain well above the Cascade passes. There might be a
slight break in precipitation at the start of next weekend, but it`s
looking more unlikely as a new system enters into the area during the
weekend. Bishop/Tolleson

.AVIATION...An incoming front will bring rain and breezy conditions
tonight with a mix of MVFR and low end VFR conditions for most taf
sites between 06-12z Monday. As winds subside towards 12z Monday,
conditions may deteriorate further into a mix of MVFR and IFR
conditions between 12-18z Monday. It appears enough low level
instability will move into the region to trend conditions towards a
mix of MVFR and VFR conditions thereafter. It should be noted that
some elevated instability pushing over our southern zones could bring
a rumble or two of thunder between 03-09z Monday to KONP and KEUG.

KPDX AND APPROACHES...An incoming front will bring rain and breezy
conditions tonight with a mix of MVFR and low end VFR conditions
between 06-12z Monday. It appears winds may weaken enough to allow
conditions to trend towards a mix of IFR and MVFR between 12-18z
Monday, but we should see enough low level instability move into the
area to allow conditions towards a mix of MVFR and VFR conditions
thereafter. /Neuman

.MARINE...A front will move southeastward across the waters this
evening and overnight. Gale Force wind gusts of 35 to 45 kt are
already spreading across the waters, and should continue until
frontal passage, which should occur between 8-10pm near the mouth of
the Columbia River and closer to 3-5am near Newport and Florence. In
the meantime, there could be a few gusts to 50 kt within 20 nm of the
coast due to coastal jet enhancement of the winds, but think this
threat should be short enough in duration to keep the Gale Warning
intact for now. Either way, expect seas to peak near 20 ft this
evening across waters. Seas should subside into the low to mid teens
fairly quickly after midnight and drop below 10 ft towards midday
Monday. The aforementioned front will actually stall across the
southern Oregon waters Monday before lifting back northward and
spreading Gale Force winds back across the waters Tuesday. Seas
should respond accordingly and climb back well into the teens where
seas look to remain through Thanksgiving. An additional storm system
or two looks possible next weekend as well. /Neuman

OR...High Wind Warning until 1 AM PST Monday for Coast Range of
     Northwest Oregon-North Oregon Coast.

     High Wind Warning until 3 AM PST Monday for Central Oregon

WA...High Wind Warning until 9 PM PST this evening for South
     Washington Coast.

     High Wind Warning until 1 AM PST Monday for Willapa Hills.

     Winter Storm Warning from 6 PM this evening to 6 AM PST Monday
     for South Washington Cascades.

PZ...Gale Warning until 10 PM PST this evening for Coastal Waters
     from Cape Shoalwater WA to Cascade Head OR out 60 NM.

     Gale Warning until 3 AM PST Monday for Coastal Waters from
     Cascade Head OR to Florence OR out 60 NM.

     Small Craft Advisory for Rough Columbia River Bar until 9 AM
     PST Monday.



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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. This area is
commonly referred to as the CWA, or forecast area. is the U.S. government's official web portal to all federal, state and local government web resources and services.