Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 210953

Area Forecast Discussion
National Weather Service Portland OR
249 AM PDT Sun Apr 21 2019

.SYNOPSIS...Onshore winds and a weak marine push will result
in cloudy skies this morning, but partial clearing is expected for
the afternoon. A front will stall north of the area early in the
week for cloudy skies and a threat of rain north of Salem Monday and
Tuesday with dry and mild weather south of Salem. Dry weather is
expected Wednesday and Thursday with daytime temperatures in the mid
to upper 60s.


.SHORT TERM...Today through Tuesday...Kind of an average spring day
today and for the next few days. Satellite shows zonal flow advancing
east across the north Pacific. Models take the storm track into
western Canada with the forecast area receiving the trailing edge of
the systems.  Today we are under weak high pressure aloft, but
surface high pressure off the coast is pushing marine clouds well
inland.  But the clouds will break up some later in the day
especially inland.  The upper and surface ridge shifts over the area
tonight so expect less marine clouds, but high clouds in advance of
the next system will be moving into the region.

By Monday the zonal Pacific jet reaches the B.C. coast with a warm
front or occluded front off the WA coast by Monday afternoon. Should
see some rain at the coat Monday afternoon then the northern half of
the forecast area Monday night and Tuesday morning.  By Tuesday
afternoon showers should be limited to the Cascades.

Temperatures will be near normal today, but will be warmer on Monday
and Tuesday as the system pull a warmer air mass into the region.

.LONG TERM...Tuesday night through Saturday...Models continue to
show a weak upper level ridge building into the Pac NW towards the
middle of the week. Aside from a few evening showers in the Cascades
on Tuesday expect conditions to remain dry through Thursday night,
with temps running a few degrees warmer than normal. Models then
start to diverge on Friday, but the general trend is to bring the
return of showers and near normal temps on Friday and Saturday as a
series of weak disturbances move across the forecast area. /64


.AVIATION...As of 09Z primarily MVFR along the coast to the
Oregon Coast Range crest and SW Washington lowlands along the
Columbia River to KKLS. VFR inland, but areas of MVFR cigs
025-030 back-building from the Cascade foothills into the east
portion of the Willamette Valley. Guidance suggests MVFR stratus
will continue to spill over the Coast Range into the interior
valleys through 13Z. The SW Washington lowlands will fill up as
well with a stratus push up the Columbia River. Expect to see
earlier improvement Sun compared to today as surface isobars
become more N to NE late Sun morning, instead of NW. All areas
VFR by 20Z and will remain VFR through 12Z Mon.

KPDX AND APPROACHES...VFR at the terminal as of 09Z, but MVFR
conditions just to the east at KTTD. Expect VFR through about
11Z Sun, then MVFR stratus reaches the terminal as it pushes up
the Columbia River. The stratus layer will be lower compared to
Sat morning, generally cigs 015-020. Improvement to VFR around
18Z with drier north low-level flow. VFR then holds through 12Z
Mon. Weishaar


.MARINE...All advisories have ended as of 09Z. The 06Z NAM and
GFS, along with the higher-resolution models, in agreement
depicting wind speeds 15 kt or less through at least 12Z Mon. The
next front reaches the north waters Mon, with 20-25 kt gusts
likely across PZZ270 late Mon morning through early evening.
Northwest to North wind develops Tue as high pressure
strengthens over the waters. Small craft advisory level wind
likely Tue through Thu, mainly afternoon and evenings.

Square sea conditions have slowly abated as dominant periods were
near 10 seconds as of 09Z. Expect wave heights around 5 ft today
through much of the week with periods 10 to 12 seconds.


PZ...Small Craft Advisory for Rough Columbia River Bar from 6 AM to
     9 AM PDT this morning.



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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 forecast area. is the U.S. government's official web portal to all federal, state and local government web resources and services.