Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 191436
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
535 AM PST Thu Jan 19 2017

.SYNOPSIS...A series of storms will continue to bring wet and
unsettled weather to Northwest California through the weekend.

&&

.DISCUSSION...Weak thunderstorms have been firing up offshore and
near the coast overnight. Aside from the lightning and thunder,
small hail and locally heavy rain has been occurring with the
isolated storms. The mid level trough axis will move through by mid
morning and an isolated storm or two will be possible near or at the
coast north of about Cape Mendocino. The thunder chances will
diminish this afternoon as the 500mb trough exits to our east.

A new storm system will quickly follow tonight. The trough aloft
will gain a slight negative tilt. This will be yet another setup
for isolated or scattered thunderstorms over the coastal waters
and perhaps along the coast. The air will be conditionally
unstable on Friday and we will once again be in a prime setup for
more storms that will generate locally heavy rain, small hail and
perhaps strong wind gusts.

Shower activity has been increasing in Trinity county this
morning. We converted the Winter Storm warning to a Winter Weather
advisory. An inch or two is expected before the shower activity
winds down by this afternoon. Another frontal system will move
through the region late tonight into Friday bringing widespread
precip. Snow levels will rise out toward the coast with the
southerlies ramping up over the coastal mountains. Snow levels
will probably remain around 3000-3500 feet in eastern Trinity per
the BUFKIT profiles. Levels should fall over the coastal ranges on
Friday after frontal passage. Elevations above 3000 ft will see
another round of heavy snow in Trinity county tonight through
Friday. A Winter Storm watch is in effect. The coastal mountains
of Humboldt and Del Norte counties may be too warm for snow down
to 3000 feet tonight. Even though the precip amounts will be
higher out over the coastal ranges, snow levels will not fall
until Friday when the precip changes over to showers in the cooler
air. A Winter Weather advisory is in effect for the interior
mountains of Humboldt county. Del Norte and northern Mendocino
counties may need to be added to the advisory. Berry Summit and
Oregon Mountain Summit may be impacted with wet heavy snow. South
Fork Mountain pass will be affected. Expect travel delays.

A third storm will rapidly develop over the weekend. This storm
will probably have greater amounts of precip along with higher
potential for strong winds. Latest GFS and NAM both indicate
fairly tight surface gradients pinching the coast Sat night with
925mb winds from 50 to 60kt. A wind advisory or high wind warning
will be possible at the coast. The strong winds may cause power
outages.

Showery conditions will persist on Monday as cool air aloft and
unstable air remains over the region. The trough aloft will pass to
our southeast on Tuesday and conditions will gradually dry out and
stabilize through the day. Overall the forecast is looking much drier
by mid next week. An offshore flow regime should bring fairly nice
days and cold mornings at the coast. Interior valleys will probably
see night and morning low clouds and fog.

Beach hazards...A high surf warning is very probable Friday night or
Saturday. A large westerly swell will start to build on Friday, but
may not reach warning level til early Saturday morning. It is too
early to hoist a warning at this time. Confidence remains high this
will be a major threat for both beachgoers and mariners, especially
on Saturday. Standby for more information and an official high surf
warning or an advisory.

&&

.AVIATION...MVFR to IFR conditions and light winds will continue
at KCEC and KACV through this morning. The lower conditions will
be due to reduced ceilings and/or visibilities due to rain showers,
stratus and patchy fog. VFR conditions and light to moderate winds
will prevail at KCEC and KACV this afternoon and evening as the
showers diminish and ceilings and visibilities increase. Showers
will move through the region tonight reducing ceilings and/or
visibilities to MVFR and temporary IFR conditions at KCEC And
KACV. MVFR to IFR conditions will continue at KUKI today due to
reduced ceilings and/or lower visibilities due to rainshowers
early this morning and stratus and/or patchy fog through the day.
The winds will be light today at KUKI.

&&

.MARINE...The winds have diminished today in the wake of a cold
front which moved across the region. The winds and seas will
increase tonight as another cold front approaches the area.
Elevated seas will persist across the waters through early next
week as a series of cold fronts move through the region. The winds
will diminish slightly Friday then increase again Friday night and
Saturday. A small craft advisory is in effect across the near
shore waters through Friday evening. The small craft advisory will
likely be extended through early next week with a hazardous seas
warning also likely along with the small craft advisory Friday
night and Saturday. A small craft advisory is in effect across the
outer waters through this evening. A gale warning will be in
effect across the outer waters this evening through Friday
morning.

&&


.EKA WATCHES/WARNINGS/ADVISORIES...
CA...Winter Weather Advisory until 10 AM PST this morning for CAZ107-
     108.

     Winter Storm Watch from this evening through Friday morning for
     CAZ107-108.

     Winter Weather Advisory from 10 PM this evening to 4 PM PST
     Friday for CAZ105-106.

NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory until 9 PM PST Friday for PZZ450-455.
Small Craft Advisory until 9 PM PST this evening for PZZ470-475.
Gale Warning from 9 PM this evening to 9 AM PST Friday for
PZZ470-475.

&&

$$

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