Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 190951

Area Forecast Discussion
National Weather Service Portland OR
250 AM PDT Mon Mar 19 2018

.SYNOPSIS...Clouds over the region today, but not much in way of
showers. This break in the weather will last through Tue. Then will
see return of clouds and rain later Tue night and Wed, with much
cooler air arriving Thu. This cooler air will maintain showers and
low snow levels for Thu into next weekend.

.SHORT TERM...Today through Wednesday...At 3 am, generally quiet
conditions across the region, under a mix of mid and high clouds. Do
have areas of fog and/or low clouds, mainly north of of a Tillamook
to Salem line. These low clouds and fog will continue to expand over
next several hours.

Upper low remnants sitting offshore this am, with showers farther
offshore. Circulation such that not many showers will make it to the
coast, as the upper flow remains southeasterly today. So, will keep
very low PoP for the Oregon coast this am, where could still see a
shower over the waters come close to shore. Otherwise, mix of sun and
clouds today with mild conditions. Will have to keep 20 pct PoPs over
the Cascades, as still have very weak instability in the
afternoon/early evening.

As the upper low offshore weakens more, cloud cover will thin
tonight. This will lead to more widespread fog and/or low clouds.

Tuesday looks mostly dry as we are mainly in between weather systems,
though some moisture may brush the eastern Lane County Cascades with
a few showers. Overall, should be great for first day of spring, with
temperatures well into the 50s, and even lower 60s for a few spots.
Will see increasing clouds later in the day to the south, mainly Lane
county, as next weather system approach

Models still say some moisture will spread up from the south Tue
night and mainly on Wed for more rain. This due to a low, currently
out near 35W/145W, is picked up ahead of and phased with the next
system dropping out of the Gulf of Alaska. There will be a bump
upward in the snow levels, but they will still tend to hover near the
elevation of the Cascade passes.       /Dean

.LONG TERM...Wednesday night through Sunday...The models are tending
to remain rather consistent with the moisture from the system west of
California spreading into northwest Oregon and southwest Washington
Wednesday night, followed by the cooler system digging south out of
the Gulf of Alaska sweeping through the forecast area Thursday. Snow
levels will drop dramatically Thursday and continue low on Friday,
with snow down into the Cascade foothills and the coastal mountains.
The parent cold upper low churns around and sends spokes of energy
onshore to keep showers and low snow levels over the area through
much of next weekend. Depending upon the details of the low, there
could be some thunder possible again late in the week or next
weekend. We should continue to add a bit of snow to the Cascade snow
pack. All in all it will be unsettled with temperatures below normal.

.AVIATION...Skies are clearing early this morning, which should
lead to areas of MVFR, IFR and LIFR conditions developing early
this morning. Expect these flight restrictions to improve to VFR
between ~17-20z Monday. MVFR, IFR and LIFR flight restrictions
should return to some taf sites towards 12z Tuesday.

KPDX AND APPROACHES...Any IFR flight restrictions that develop
early this morning should improve to VFR between 17-19z Monday.
Clear skies and light winds may lead to additional flight
restrictions developing towards 12z Tuesday.  /Neuman

.MARINE...Expect winds to generally remain less than 20 kt
through midweek. Models continue to show a more active weather
pattern returning Thursday and continuing through the weekend.
Small Craft Advisory level wind gusts of 25 to 30 kt and seas
climbing into the low to mid teens appear most likely during this
time. /Neuman



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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.