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fxus66 keka 221213 

Area forecast discussion
National Weather Service Eureka California
413 am PST Fri Nov 22 2019

Synopsis...expect another sunny and mild day today, with Pacific
high pressure keeping the weather quiet through the weekend. A
colder and wetter weather pattern will arrive next week.


Discussion...clear skies continue to prevail across northwest
California this morning, with the exception of some patchy stratus
lingering along the southern Mendocino coast. The clear skies and
light winds are supporting another cold morning across the area,
with widespread temperatures in the upper 20s to low 30s across the
interior and dipping into the upper 30s along the coast. A fairly
benign upper level pattern will yield another mostly sunny day with
mild temperatures. A weak and compact shortwave trough dropping
south along the coast will brush the area this afternoon and then
pass to the southwest overnight. This feature will have little
impact on sensible weather conditions other than to slightly deepen
the marine layer and possibly provide a slightly higher threat of
some stratus intruding along the coast overnight, although weak
offshore flow will also be present to limit that potential. An
elongated area of high pressure centered well offshore near 140w
will then build into the region on Saturday, supporting continued
quiet weather and slightly warmer inland temperatures for the
weekend. The pattern will begin to amplify late Sunday into Monday
as the ridge axis shifts offshore and allows another shortwave to
approach the area in northwest flow aloft. This feature looks to
provide more of a glancing blow to the area at this point as it
passes just to the north and east, with impacts likely limited to
increasing cloud cover across the area and a few sprinkles near
the or border. /Cb


Long term...a large-scale pattern change is still on tap for next
week. While individual model runs have been inconsistent with the
details, there is unanimous support for the change in the pattern,
with all solutions pointing toward a deep, cold trough dropping
across the West Coast by the middle of next week. The initial
surface low and associated fronts will begin impacting our area as
early as Tuesday, and likely continuing into Wednesday. Depending on
the storm track, rainfall may vary anywhere from a quarter-inch to
few inches, with the ultimate outcome more likely somewhere in
between. The overall pattern is supportive of a colder storm, with
snow levels dropping below 3000 feet by Tuesday and Wednesday. The
notable concern with this system will be impacts to pre-
Thanksgiving travel. /Aad


Aviation...clear skies and light winds continue across the area
this morning. There is some stratus starting to develop offshore,
but so far it is not very extensive. Most models are keeping this
out of the taf sites this afternoon, although if it expands more
than expected some could move into kacv late in the afternoon. At
this point confidence is too low to put it in the forecast. Late
tonight into Saturday morning there may be a short period of
stratus at kacv, but confidence is low on this as well due to a
weak shortwave moving down the coast and high pressure building in
on Saturday. Winds are expected to generally remain less than 10
kt at the taf sites through tonight. Mkk


Marine...the northwest swell has started to build into the waters
this morning. Currently the dominant swell is still the northwest
swell which is around 5 feet at 13 seconds, but the long period
swell has started to show up around 20 seconds. This swell is
expected to build to around 12 feet at 16 seconds by late this
afternoon. There is also a short period swell around 3 feet at 8
seconds. Northerly winds will increase slightly this afternoon to
5 to 15 kt with the strongest winds over the outer waters. This
will start to generate some short period wind driven waves as

This weekend the northerly winds will increase to around 10 to 20
kt. This will generate some short period waves of 6 to 10 feet
around 8 seconds. Due to the long duration of these moderate
northerly winds this will increase the short period waves. Sunday
night and Monday the northerly winds will continue to increase to
15 to 25 knots. The strongest winds will be over the southern outer
waters where a few gale force gusts are possible. This will
develop large short period waves up to 12 feet.

Tuesday winds will rapidly diminish as a strong weather system
approaches the area. Some models show a fairly strong area of low
pressure moving onshore Tuesday night. Confidence is low on the
strength and timing of this feature and it could have a big
impact on the wind speeds and direction for the Tuesday/Wednesday
time frame. Late in the week confidence is higher that we will see
high pressure build back bringing a return of moderate to
possibly strong northerlies.

Another northwest swell will build into the waters on Sunday
pushing periods back up to near 18 seconds. This will keep wave
heights in the 10 to 12 foot range. Monday this will happen again
with yet another swell moving into the waters. The swell is
expected to remain over 10 feet through the middle of the week and
a Small Craft Advisory will likely be needed. Mkk


Eka watches/warnings/advisories...
Northwest California coastal waters...Small Craft Advisory from 3
PM this afternoon to 3 PM PST Sunday for pzz450-455.

Small Craft Advisory from 9 am this morning to 3 PM PST Sunday
for pzz470-475.



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