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National Weather Service Area Forecast Discussion for Seaside, OR USA

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Area Forecast Discussion
National Weather Service Portland, OR or
1221 pm pdt mon oct 23 2017

.synopsis...strong high pressure will sit over the pac nw this week,
with dry and mild conditions. will see areas of late night/am fog and
low clouds, mainly for interior valleys. some threat of showers wed
as weak front moves across the region. then back to mild and dry,
with breezy offshore winds for thu into next weekend.

&&

.short term...tonight through wednesday...building high pressure
ridge over the region will maintain dry and mild conditions for a
while. surface high pressure east of the cascades will dominate
weather for next few days, with increasing offshore flow tonight.

should see lot less in way of low clouds and fog tonight. most likely
areas will be in willamette valley south of salem, and in the cowlitz
valley. with increasing offshore winds, will see drier air increasing
on the west side. this will work to erode fog/low clouds later
tonight into tue am.

speaking of which, these east winds will becoming gusty over the
higher terrain and through the columbia river gorge later tonight as
the offshore pressure gradient strengthens. gusts of 30 to 45 mph
expected for the higher terrain of the willapa hills, coast range and
the cascades later tonight through good part of tue. the east winds
will gust 25 to 40 mph across the east side of portland/vancouver
metro, with gusts up to 50 mph in the western columbia river gorge.

with 850 mb temps climbing into the upper teens celsius, the coast
range and lower to midslopes of the cascades should easily reach the
70s, and perhaps approach 80 degrees tue afternoon. with 500 mb
heights exceeding 590 dm, there will be inversions which will likely
keep valleys a bit cooler, but still in the the mid to upper 60s.

the upper ridge flattens tue night, with a weak system drops
across the pac nw wed and wed night. will see light onshore flow at
that time, with some threat of showers. best threat of showers will
over the cascades north of santiam pass. even so, rainfall amounts
will be spotty and light.       rockey.

.long term...wednesday night through sunday...high pressure will
rebuild over the pac nw thu and fri, and hold in place into next
week. this will maintain mild and dry conditions, as well as varying
degrees of offshore flow. expect breezy east winds for thu night
through early sat, especially over the higher terrain and in western
columbia river gorge. in fact, if current trend pans out, this would
be a dry and mild halloween, the first since 2007. rockey.


&&


.aviation...ifr fog and low clouds over the lowlands this
morning have mostly cleared at this point. the exception is a small
patch of stratus in the southern willamette valley, which should
also burn off within the next hour. then widespread vfr conditions
will remain in control through this evening. strengthening offshore
flow overnight should keep the coast and the northern portions of
the interior lowlands cloud free tonight and tue morning. the
southern half of the willamette valley is more uncertain. keug and
possibly ksle could see a period of fog overnight into tue morning.
however, ne flow may develop through the valley, which would prevent
much fog from forming in these locations either.

kpdx and approaches...vfr conditions expected to remain through the
next 24 hrs. easterly flow will develop overnight and remain through
tue, which should keep any low clouds or fog from forming overnight.
gust east winds out towards the gorge will affect easterly
approaches tonight and much of tue. pyle


&&


.marine...high pressure building over the ne pac will remain in
place through most of the next 7 days. meanwhile, a thermally
induced surface low will remain over the northern ca and southern or
coast. this pattern will result in persist n-ne winds. the winds
will be gusty at times. based on the latest model guidance, decided
to issue a small craft advisory for winds for the outer waters from
this evening through tue night. expect gusts of 20-25 kt during this
time. winds will be lighter over the inner waters. a weak front will
move through the waters wed, which will briefly weaken the ne pac
high and turn winds weak westerly. gustier northerly winds will
return for later in the week.

seas remain 10 to 11 ft this afternoon, so have kept the small craft
advisory for seas through this evening. seas will drop below 10 ft
later this evening, then continue to fall over the next couple of
days. they will be around 6 ft by wednesday, and stay in the 5 to 7
ft through friday. pyle


&&


.pqr watches/warnings/advisories...
or...none.
wa...none.
pz...small craft advisory for winds from 8 pm this evening to 5 am
      pdt wednesday for waters from cape shoalwater wa to
      cascade head or from 10 to 60 nm-waters from cascade head
      to florence or from 10 to 60 nm.

     small craft advisory for hazardous seas until 11 pm pdt this
      evening for coastal waters from cape shoalwater wa to
      cascade head or out 10 nm-coastal waters from cascade head
      to florence or out 10 nm-waters from cape shoalwater wa to
      cascade head or from 10 to 60 nm-waters from cascade head
      to florence or from 10 to 60 nm.

     small craft advisory for rough columbia river bar until 11 pm
      pdt this evening.

     small craft advisory for rough columbia river bar from 6 am to
      10 am pdt tuesday.

&&


$$

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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

Information courtesy of the National Weather Service - NWS Portland...
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