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

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Area Forecast Discussion...updated
National Weather Service Portland, OR or
845 pm pdt thu oct 29 2020

.synopsis...a weakening front will bring clouds and showers to the
region on friday, mainly through mid-day. then, back to dry weather
for a bit, though will see areas of late night/morning fog again
this weekend. rather zonal flow into the pac nw next week, with a
series of fronts expected. this will bring lot more in way of clouds,
and rain at times next week.

&&

.short term...tonight through sunday...clouds never quite cleared
south of salem this afternoon, and cigs/vsbys are beginning to lower
at corvallis, eugene, and creswell while the overall area of fog/low
clouds slowly expands this evening. updated the sky cover forecast
earlier in the shift to reflect the satellite/observational trends.
with skies never having cleared, temperatures failed to rise much
above 50 degrees for the southern willamette valley. aside from the
stubborn low clouds and fog, the remainder of the forecast looked to
be in good shape with only a few mainly cosmetic tweaks needed to the
forecast.

satellite imagery reveals a maturing low near the southern tip of
haida gwaii, pushing a cold front southeast toward wa/or. this front
to move to the coast late tonight then across the interior during the
morning hours. but before that we will likely have enough clearing
before frontal clouds arrive for some fog to redevelop in the
interior valleys. front is not all that strong, with modest lift as
the forecast area is more in the tail end of the front. the bulk of
the moisture is below 850 mb so the coastal mountains will cut into
rain amounts reaching the valley. looks like the southwest wa zones
will have the higher rain amounts. high pressure builds back into
the region later friday and friday night. so, will see clearing skies
friday night, with areas of fog again. overall, mild again on
saturday, under variable high clouds. could see bit of north to
northeast flow aloft, which give bit more support for mild
temperatures on saturday.  weagle/mh

.long term...sunday night through wednesday...as we switch from
october to november, almost like clockwork we transition into a
progressive pattern.  high pressure at the surface and aloft will
hold through at least monday morning. during this time will likely
see valley temperatures inversions for at least some fog or low
clouds in the morning with afternoon sunshine and temperatures
climbing to the upper 50s to low 60s.  but by monday morning the
ridge has shifted east of the cascades. this will open the door to a
series of fronts moving through during the week. the first front
arrives later monday into tuesday but is in a weakening state by the
time it arrives.  this may be delayed or weakened further as cluster
analysis has some of the groups weakening the ridge less.
stronger fronts arrives for the latter half of the week as a much
zonal jet noses into western wa beginning wed. 12z ecmwf & gfs
currently indicating the jet peaking 150-160 kt wed evening. the
forecast area will be in the warmer side of the jet so snowlevel will
be above cascade peaks. /mh


&&

.aviation...vfr skc across most of the area as of 0330z. the
exception is an area of ifr to lifr in the central and south
willamette valley. this has has been slowly expanding north and
will likely impact ksle by 05z. expect increasing ifr or lower
conditions north of ksle overnight. meanwhile, mid and high level
clouds associated with the leading edge of an approaching
frontal system had reached the washington coast near khqm. there
is a mass of stratus beneath these mid and high clouds and expect
mvfr flight conditions to develop along the south washington and
north oregon coast by 06z.

a predominant mix of ifr and mvfr will cover the northwest half
of the forecast area from 10z through about 19z fri. ifr to lifr
will persist in the willamette valley south of ks12 through 10z.
gradual improvement occurs after 10z as a south surface wind
helps to mix out the fog. the southern half of the area west of
the cascades will be in mainly mvfr conditions late tonight
through friday morning. the central cascades should hold on to
vfr at least til 14z fri and then endure a 4-5 hour period of
sub-vfr conditions.

for detailed regional pac nw weather information, go online to:
http://weather.gov/zse

kpdx and approaches...vfr skc as of 0330z, but am expecting ifr
to develop around 07z. the tualatin river valley will likely see
lifr a little earlier. a mix of ifr to mvfr holds through 10z and
then mainly mvfr until 19z. improvement to vfr after 19z in the
post-frontal air mass. weishaar

&&

.marine...little change to current forecast. north wind will
continue across the waters tonight, but will be under 15 kt. low
pressure will move into the queen charlotte sound late tonight
with an associated cold front moving through the waters early
friday morning. strongest wind looks to stay confined to zones
pzz270 and pzz250 with gusts to 25 kt expected. model output
shows seas building to around 10 ft friday afternoon and then
subsiding by friday night.

high pressure returns friday afternoon with a surface thermal
trough developing fri night along the north california and far
south oregon waters. this thermal trough expands north saturday
for a return of north wind. model output shows the possibility of
25 kt gusts over pzz255 and pzz275 sat afternoon through sat
night. the new fresh swell will create steep and choppy
conditions over the weekend. weishaar

&&

.pqr watches/warnings/advisories...
or...none.
wa...none.
pz...small craft advisory until 11 pm pdt friday for coastal waters
     from cape shoalwater wa to cascade head or out 60 nm.

&&

$$

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