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

fxus66 kpqr 102239

Area Forecast Discussion
National Weather Service Portland, OR or
239 pm pst sun dec 10 2017

.synopsis...high pressure will continue to bring cool temperatures
and areas of morning fog and frost before a transition to a more
typical wet december returns towards late in the work week or next
weekend. gusty gorge winds will continue but likely weaken tuesday
and wednesday.


.short term...tonight through wednesday...the upper ridge will
remain over the pacnw through the period. monday and monday
night/early tuesday, however, the axis will get pushed eastward by a
short-wave riding north roughly along 130w. there is a decaying
front associated with it which may hold together long enough to
bring light rain to the waters. more importantly to some though, the
building surface high pressure behind the front will greatly weaken
the pressure gradient across the cascades. the east winds will not
disappear completely, but there appears to be about a 36 hour period
where the cold pool drainage is driving the flow about as much as
the weak pressure gradient. average gusts near the western gorge
will be about 20 mph lower by tuesday night and early wednesday down
to a paltry 35-40 mph versus the 55-60 mph, and locally higher,
speeds today and monday.

still appears fog and/or all day low clouds will stay confined to
the eastern gorge and portions of the southern willamette valley
tomorrow through wednesday. areas which do not break free of the
stratus, like hood river, will struggle to make it above the
freezing mark while the remaining lower elevations will make it into
the upper 30s to lower 40s. the foothill and higher elevations will
continue to see the upper 40s to lower 50s. higher clouds increase
following the aforementioned short wave and may keep overall
temperatures cooler and also make it harder for the fog and stratus
to burn off wednesday for more areas with high temperatures closer
to the freezing mark. that will all depend om the thickness of the
high clouds with confidence rather shaky. /jbonk

.long term...wednesday night through sunday...ridging will keep us
dry into thursday.  models have pushed back the onset of
precipitation to 10pm thursday night at the earliest on the coast
and friday morning in the willamette valley.  this may help lower
the chance for freezing rain in the hood river valley. the later the
precip arrives in the morning, the less chance of freezing rain at
onset. this is still a time period to watch over the next few days.

once rain starts, we get into more of a zonal flow pattern as the
ridge of high pressure gets squashed down by a longwave trough
digging into the gulf of alaska over the weekend. this means our
winter rains return. we may get a break in the precipitation on
saturday before another system swings through on sunday, but the
timing of this break is uncertain at this time.

snow levels will be coming down to 3000 to 4000 ft behind this first
front friday night, bringing snow to the resorts passes friday night
into early saturday morning.  snow levels lift back up to 6000-8000
ft for the onset of the next system on sunday. -mccoy


.aviation...gusty east winds continue through the columbia river
gorge and along the coast at least through monday morning.
widespread vfr conditions tonight and monday morning except for
near keug and kcvo where fog will result in ifr conditions, and
for mvfr stratus in the columbia gorge and the upper hood river
valley. the east winds should decrease monday night.

pdx and approaches...vfr conditions continue next 24 hours. gusty
east winds this evening should decrease late tonight. the east
winds will increase again late monday morning, but should not be
as strong as they were today. ~tj


.marine...breezy east winds will continue through the coastal
gaps tonight with localized gusts near 25 kt. a secondary longer
period nw swell builds in the waters tonight. this swell will
build to 4 to 5 feet by monday as the current sw swell continues.
the wave periods from these two swells will become similar monday
night making it more difficult to distinguish the two swells.
the significant wave heights will build to 9 feet monday night
into early tuesday morning.

a weakening front will produce south winds in the waters monday
night. marginal small craft winds are possible beyond 40 nm and
north of cascade head monday night, but these are not widespread
enough to warrant an advisory for all of marine zone 270. east
winds return wednesday. another front approaches on thursday and
is expected to move across the waters thursday night into friday
for a better chance of widespread small craft advisory

the east winds have minimized the normal impacts of the ebbs on
seas the past couple of days, and do not expect tonight and
monday morning`s ebbs to raise the seas much. ~tj


.pqr watches/warnings/advisories...
or...air stagnation advisory until 2 pm pst thursday for central
     willamette valley-lower columbia-south willamette valley.

wa...air stagnation advisory until 2 pm pst thursday for greater
     vancouver area-i-5 corridor in cowlitz county.



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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.

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