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National Weather Service Area Forecast Discussion for Long Beach, WA USA

fxus66 kpqr 201030

Area Forecast Discussion
National Weather Service Portland, OR or
318 am pdt sun aug 20 2017

.synopsis...onshore flow will produce varying degrees of morning
clouds, afternoon sunshine and inland temperatures in the 70s and
80s for much of the next week with monday and tuesday likely being
the warmest. a weak storm system could bring a few light showers
late wednesday and thursday before temperatures warm back to
above average levels next weekend.


.short through wednesday...fog product early this
morning reveals very little cloud cover across the area. high clouds
streaming southeastward out of canada should spread across the area
today, but these should dissipate this evening and overnight as an
upper level ridge rolls over the pacific northwest.

a weak shortwave trough sliding southeastward across the rockies this
afternoon and evening will maintain onshore pressure gradients
across the cwa despite the upper level ridge impinging on the
region. with marine clouds currently congealing offshore, there
should be more marine clouds monday morning when compared to this
morning, particularly along the north oregon coast and lower reaches
of the columbia river valley...perhaps making it to the eastern pdx
metro for a couple hours between 7-10am.

some models suggest marine clouds will push onto the central
oregon coast late sunday night and monday morning, but with winds
turning slightly offshore, particularly around 925mb, suspect there
should be at least some clear patches along the central oregon coast
monday morning. all in all, monday should be a good day to view the
eclipse across most of the cwa with with inland temperatures
climbing well into the 80s. some model guidance even suggests low
90s in the willamette valley, but given the decrease in solar
insolation monday morning due to the eclipse, held temperatures on
the cool side of mos guidance for monday.

it should be noted that winds turn weakly easterly around 850mb
towards midday monday, which may allow some smoke from the wildfires
in lane and linn counties to drift over portions of the central and
southern willamette valley monday afternoon and evening.

expect tuesday to be a near repeat of monday except the winds aloft
turn a little more westerly, which will limit any smoke issues to
those in the immediate vicinity of the current wildfires. some
modest instability over south central oregon could clip far eastern
lane county late tuesday afternoon or evening and again on
wednesday, but suspect thunderstorms will most likely remain east of
the cascades. the next storm system is on track to bring a dying
front, increased cloudiness, cooler temperatures and possibly some
light showers to the region late wednesday. /neuman

.long term...wednesday night through sunday...models are in good
agreement a shortwave trough will slide eastward across british
columbia and washington wednesday night and thursday. this should
bring cooler temperatures, increased cloud cover and a chance of
light rain, particularly along the coast and across the cascade
foothills, but even portions of the willamette valley could see some
light rain. shortwave ridging should then build over the pacific
northwest and bring a return to more sunshine and above average
temperatures towards next weekend. /neuman


.aviation...starting to think there will not be any stratus along
the coast this morning given the current satellite trends. with
good radiational cooling, some fog development is possible in a
few of the coastal valleys. this fog will stay confined to areas
sheltered by the wind. therefore, do not expect any fog
developments at kast or konp. inland, dry conditions should
supersede any fog/low stratus development.

kpdx and approaches...vfr conditions through the period. do not
expect any stratus to develop in the area of the terminal this
morning. /bentley


.marine...a persistent weather pattern will result in little
change in the marine weather the next several days. high pressure
holds over the ne pacific while a thermal trough is along the
south oregon coast. this supports north winds across the south
washington and north oregon waters. the thermal trough
strengthens each afternoon such that the north winds will
increase and become gusty each afternoon. the winds south of
cascade head will have frequent gusts to around 25 kt which
supports the current small craft advisory for winds.

the seas will be locally generated from these winds and generally
remain 4 to 6 ft with periods at 9 to 10 seconds. the seas will
be choppier in the southern waters for the afternoons with
dominant periods possibly around 8 seconds. bentley


.pqr watches/warnings/advisories...
pz...small craft advisory for winds until 11 pm pdt monday for
     coastal waters from cascade head or to florence or out 60



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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.

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