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

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Area Forecast Discussion
National Weather Service Portland, OR or
215 am pdt thu may 23 2019

.synopsis...a ridge of high pressyure off the coast will bring
warmer temepratures today, while low pressure to the east keeps a
chance for showers and thunderstorms, mainly for the cascades. on
friday an upper level low pressure system will move down the british
columbia coast and over the pacific northwest, bringing cooler
temperatures and renewed chances for showers lasting through the
weekend.

&&

.short term...today through saturday...the upper low pver the
desert southwest early this morning is expected to lift north
through utah today and into wyoming tonight. cascades remain on the
northwest periphery of the closed low today, leaving the area open
to a chance for showers and thunderstorms. areas further west
however are likely to remain dry today and tonight as a ridge of
high pressure aloft offshore presses closer to the coast and raises
heights aloft. this also expected to result in warmer temperatures
for much of the area today as 850 mb temperatures climb several
degrees.

models agree on a shortwave moving south down the british columbia
and washington coast friday, digging in for a closed low sinking
south over the region friday night. a surface trough of low pressure
trailing the low to the north, brings enhanced low level onshore
flow to the region friday. this brings a chance for showers back to
the entire region, but pops will be a bit on the conservative side
generally chance category except over terrain in the north, as
moisture is limited to just the very low elevations. a second low
follows the first one down the coastline on saturday, maintaining a
showery cool air mass for the area.

.long term...saturday night through wednesday...no changes.
previous discussion follows. the models agree on the general trend
throughout the extended. a low will slowly track over the forecast
area through sunday leaving a wake of shortwaves that will keep
chances of precipitation within the forecast through monday night.
the euro is leaning more towards the wetter side as its low has a
more organized circulation and stronger frontal formation, this
results in more rain. the forecast however, is leaning more towards
the gfs which still shows precipitation but not as heavy. both
models show heavier precipitation in the cascades monday night.

a high pressure moving in from off-shore tuesday will reduce
precipitation for the rest of the extended. a notable feature will be
the inversions that occur sunday through tuesday in the early
morning hours (around 5am); this will increase temperatures above
1500ft by roughly 5 degrees. -bphillips

&&

.aviation...mvfr stratus beginning to develop inland will spread
through the rest of the inland sites through thursday morning.
coastal sites will drop to ifr through the night and likely not
improve above mvfr during the day thursday. inland site should
clear out thursday afternoon but for some cirrus.

kpdx and approaches...mvfr stratus returning and lasting through
about 18z or 19z thursday, then vfr. light and variable winds
overnight, become northwest round 10 kt thursday afternoon. bowen


&&

.marine...latest buoy obs show winds below 20 kt and they were
marginal earlier even at buoy 89, so have dropped current small
craft advisory for winds. however, it does look like winds will
pick up again out of the northwest behind the current system over
the waters beyond about 15 nm offshore, so added a new small
craft advisory for winds starting 5 pm pdt thursday.

this northerly wind pattern continues through at the weekend.
it appears winds weaken over the weekend. meanwhile, seas have
dropped some to 8 to 9 ft at 8 to 10 seconds. have kept the small
craft advisory for hazardous seas in place as it, but will not
extend as seas will continue to drop a little bit with dominant
wave period remaining around 9 seconds.

model guidance shows seas exceeding 10 ft again friday night as
the next low pressure area along the british columbia coast drops
south. latest spectral guidance has seas peaking around 14 ft in
the northern outer waters. seas then fall just below 10 ft
saturday and look to continue falling through sunday to around 4
to 5 feet. bowen


&&

.pqr watches/warnings/advisories...
or...none.
wa...none.
pz...small craft advisory for winds from 5 pm this afternoon to 5 am
     pdt friday for waters from cape shoalwater wa to florence
     or from 10 to 60 nm.

     small craft advisory for hazardous seas until 11 am pdt this
     morning for coastal waters from cape shoalwater wa to
     florence or out 60 nm.
&&

$$

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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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