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
932 am pst tue jan 19 2021

updated aviation discussion

.synopsis...dry weather is expected through wednesday. a low
pressure system will provide a chance for showers on thursday with
snow levels mostly between 2000 and 3000 feet. dry but cooler
weather is expected on friday and saturday. a cold front will
provide the chance for lower elevation snow sunday and monday.

&&

.short term...today through thursday night...mostly clear skies and
light winds overnight is resulting in a cool and frosty morning. the
temperatures are much cooler than they have been the past several
nights, but are actually in line with what is normally expected for
this time of the year. fog and low clouds are mostly limited to the
south willamette valley, but satellite and temperature/dewpoint
spreads indicate that localized fog is forming near and along the
columbia and the willamette rivers. light offshore flow will support
mostly sunny skies into the afternoon with temperatures warming into
the upper 40s to lower 50s this afternoon, which are also typical
for the season. offshore flow decreases this afternoon and evening,
and light winds and mostly clear skies will lead to another night
with near freezing temperatures.

clouds will increase from north to south on wednesday as a weak low
approaches, but otherwise there will be little change in the overall
weather with near seasonal temperatures persisting. the low will
remain offshore as it moves south along the south washington coast
wednesday night and the oregon coast on thursday. patchy drizzle is
possible overnight wednesday across sw washington and extreme north
oregon, then a chance for showers is expected across the area mid
thursday morning through thursday night. snow levels will generally
be around 2500 to 3000 feet, although there will locally be lower
snow levels between 1000 and 1500 feet for the upper hood valley,
central columbia gorge, and portions of sw washington. rain and snow
totals will be light with 0.15 to 0.25 inch of rain expected from
salem and southward, and 0.05 to 0.15 inch for north of salem. the
cascades could measure 1 to 3 inches of snow with the higher amounts
across the cascades of lane county. these precipitation totals are
from thursday morning through thursday night. cooler air moves in
behind the low as it moves south, and temperatures thursday afternoon
are expected to be a few degrees cooler. ~tj

.long term...friday through monday...showers wrapping around a south
moving low may continue into friday even though the low should be
well into california. an overall cooler pattern is expected friday
into the weekend as north flow is established. the models are still
forecasting the possibility for an even cooler weather system sunday
night through monday, and are actually stronger with the cooling and
moisture associated with it. there is increasing confidence that the
snow levels will be low (500 to 1000 feet) with the onset of
precipitation saturday night into sunday morning, providing the first
chance for widespread low elevation snow this winter. snow levels
should rise to 1000 to 2000 feet sunday afternoon and evening, but
forecast confidence on the snow levels and timing of them rising
remain low. a series of shortwave may continue the chance for
precipitation with 1000 to 2000 feet snow levels through monday. for
what it is worth, the nbm is forecasting a 90 to 100 percent chance
of snow for the willamette valley from portland to eugene with a
range of 0.5 to 1.5 inch of total snow. there is much greater
confidence that the cascades, cascade foothills, and coast
range will have snow accumulations with this event. forecast
confidence for this day 5-7 forecast period has improved from 24
hours ago, but is still low. ~tj

&&

.aviation...the 18z taf period is highlighted by scattered high
clouds, light and variable winds away from the west gorge, and
vfr flight conditions. the except to this is at keug where low
stratus with cigs between 400-500 feet will linger through this
morning before giving way to scattered high clouds this
afternoon. expecting shallow patchy fog and low stratus to form
near keug again tonight, especially after 12z wednesday. fog
and/or low stratus is not expected at any of the other taf sites
throughout the 18z taf period. at kttd, expect breezy east winds
between 15-20 kt to continue through 01-02z, before falling below
10 kt by 03-04z.

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

kpdx and approaches...expect vfr flight conditions through 18z
wednesday as scattered high clouds continue along with light and
variable winds. there is the potential for frost again tonight as
temperatures drop to near freezing, especially on exposed
surfaces. some very shallow patchy ground fog is also possible
between 09-14z wednesday, but any visibility reductions would
most likely be insignificant and short-lived. -tk


&&

.marine...high pressure remains anchored over the are with an
thermally induced trough stretched from the northern california
coast to the washington coast. conditions will remain settled
through wednesday as this high pressure persists. offshore winds
today will begin to shift to a weak onshore flow. while onshore,
not expecting winds to exceed gusts of 15 to 20 kt. a slight bump
up in winds possible on thursday as a very weak front moves over
the waters. ultimately though, not expecting winds to reach small
craft speeds. seas will also remain mild through the week. swells
around 8 ft at 15 seconds will be the norm with minimal wind
waves. there is a chance for some building seas on thursday and
with the introduction of a bit more of a wind wave, however it
likely will be isolated to the far outer waters. more active
weather possible over the weekend.   -muessle

&&

.pqr watches/warnings/advisories...
or...none.
wa...none.
pz...none.
&&

$$

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