Skip to main content.

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

000
fxus66 kpqr 171651
afdpqr

Area Forecast Discussion
national service portland or
917 am pdt wed jul 17 2019

.synopsis...a frontal system will result in light rain spreading
southward across the area today and tonight. drier and cooler air
arrives behind the front. then warmer weather is expected for the
weekend.

&&

.short term...today through friday...water vapor satellite imagery
reveals an unusually strong jet stream stretching across the lower
gulf of alaska that is taking aim at southern british columbia and
washington state. models have initialized a 160-170 kt jet off the
coast, which will weaken as it pushes inland over the next 12-24
hours, but even then it may end up outside what has been observed
over washington state this time of the year via a 30 year naefs
reanalysis climatology. closer to the surface, an extensive area of
clouds composed of multiple decks is apparent over the northeast
pacific via visible satellite imagery. the bulk of these clouds
are forming in an area of weak warm advection, which will slowly sag
southward across the area today. this should result in areas of
drizzle and light rain spreading southward across the area this
afternoon and evening. there may be just enough westerly flow to
produce some rain shadowing in the western portions of the willamette
valley, though. with relatively high precipitable water values,
hourly rainfall rates could peak in the 0.1"-0.2"/hour range across
the most favored west facing slopes in the coast range, particularly
in tillamook county and points northward near the coast.

between drier air pushing in behind a trailing cold front tonight and
a lowering subsidence inversion, expect rain chances to decrease
rather markedly late tonight into thursday morning. continuing
onshore flow on thursday should should result in high temperatures
topping out a few degrees below average.

another shortwave trough will swing around the parent gulf of alaska
trough and brush the region thursday night into friday morning. this
could result in some light showers streaming onto our north coast
during this time so will likely add at least some mentionable pops
with the afternoon forecast package. in addition, it will keep high
temperatures several degrees below average on friday.

it should also be noted that dewpoints should drop closer to more
typical levels around 50f, which should result in thursday and
friday feeling much less muggy than the past week or so. /neuman


.long term...friday night through tuesday...no changes...previous
discussion follows...a high pressure ridge builds over northwest
oregon and southwest washington through monday. this will keep
conditions fairly clear and dry through the weekend with warming
temperatures. models are hesitating a little bit regarding exactly
how warm it will get, so didn`t end up changing temperatures much at
all. hopefully models will get into better agreement over the next 24
hours. the ridge begins to weaken monday night as an upper trough
approaches from the northwest. however, will only see a little bit in
the way of cooling by tuesday. overall, the long term looks dry and
seasonably warm. bowen


&&


.aviation...a warm front along the sw washington coast is
resulting in mostly mvfr conditions for the north coast, with
ceilings flirting with ifr. the rain and mvfr conditions will
extend further south along the coast, impacting ktmk, konp and
possibly k6s2 by 18z. the mvfr-ifr conditions will linger along
the coast into this evening and through tonight as a weak cold
front replaces the warm one around 0z.

inland areas...the warm front will bring mvfr conditions for the
sw washington cascades and extreme north cascades this afternoon
around 20z and possibly impacting k4s2 and kttd. vfr will likely
remain in the willamette valley most of today with the best
possibility for mvfr conditions this evening and tonight.
forecast soundings suggest the ceilings tonight will be around
1500 to 2500 ft.

kpdx and approaches...vfr prevailing with 4000-7000 ft ceilings
this morning. ceilings of 3500-4000 feet will become more
dominant this afternoon after 22z when a weak warm front moves
across the area. there is a better chance for mvfr ceilings
around 1500-2500 feet tonight after 0z as a dissipating cold
front moves inland from the coast. south winds this morning
should become sw-w around 0z. showers will end early thursday
morning with vfr returning. ~tj


&&


.marine...buoy #46029 shows marginal small craft winds this
morning with a warm front supporting the current small craft
advisory. seas are a mix of wind waves and a small (3 feet) long
period (18 sec) southwest swell. the waters south of pacific city
will briefly gust 21-25 kt later this afternoon, but do not
anticipate these stronger gusts to reach south of newport. ~tj

from previous discussion sent at 256 am...high pressure begins
to rebuild offshore on thursday and strengthens for the weekend.
this will result in a return to northerly winds through early
next week. gusts of 25-30 kt can be expected for the weekend with
the strongest winds beyond 10 nm offshore.

seas start in the 3 to 4 ft range, then build to around 8 feet
thursday morning. seas will be choppy as this system passes with
the potential for square seas on thursday morning. seas will
stay above 5 ft through the weekend. the larger seas are a
product of the increased wind wave height from the short wave
system that moves through wednesday night into thursday but also
from a swell out of the nw that will be the dominant swell
throughout the forecast time period. -bphillips/mh


&&


.pqr watches/warnings/advisories...
or...none.
wa...none.
pz...small craft advisory until 5 pm pdt this afternoon for coastal
     waters from cape shoalwater wa to cascade head or out 60
     nm.

     small craft advisory until 2 pm pdt this afternoon for coastal
     waters from cascade head or to florence or out 60 nm.

&&


$$

interact with us via social media: www.facebook.com/nwsportland
www.twitter.com/nwsportland

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...
Issuing Weather Forecast Discussion Homepage