Small Craft Advisory 5, NWS Eureka, CA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
257 PM PST Thu Jan 11 2024

.SYNOPSIS...Mostly dry weather is expected tonight, although a
few very light showers are possible in Humboldt and Del Norte. The
next system starts to bring rain Friday, spreading south through
the afternoon. Heavy rain is expected Friday night and Saturday
along with strong winds. Heavy snow is possible in northeastern
Trinity county. Drier weather is expected Sunday and Monday with
additional systems possible by mid week.

&&

.DISCUSSION...High pressure has built in rapidly to the area
today, with our barometer on Woodley reading a +0.3 in Hg increase
in the last 24 hours. A weak disturbance is currently slipping over
this ridge is bringing some clouds and intermittent light rain to
Del Norte and Humboldt counties. This is expected to continue
through tonight.

Friday these showers are expected to gradually increase in coverage
and eventually become widespread stratiform rain. This rain is
expected to become heavy for nearly a 24 hour period Friday night
and Saturday with a strong plume of moisture moving over the area.
The current forecast remains nearly unchanged, calling for
widespread amounts of 2 to 3 inches, with a couple local maxima of 5
inches or more in the mountains of Del Norte and the King Range.
Lake county will likely see the least rain with amounts in the
southeast from Clearlake to Cache Creek only slightly over an inch.
This rain will likely cause small stream flooding and a flood watch
may be needed for Humboldt and Del Norte counties. There is still
some uncertainty on how heavy the rain will be, but the ground is
pretty saturated and there will be more runoff. Currently none of
the main stem rivers are expected to see flooding, but a couple
could reach monitor stage. Strong winds are expected with this
system as well, mainly in Humboldt and Del Norte counties. Gusts to
45 mph are possible in Crescent City and gusts to 50 mph are
possible over the higher terrain in these counties.

In northeastern Trinity county the cold air may linger and upsloping
may also help reduce snow levels. There is a lot of uncertainty on
how low they will be and where where they will be low. Typically
with this pattern it is an area north and east of Hayfork. For now
have the snow levels between 2,500 and 3,000 which would impact Hwy
299 at Buckhorn Summit as well as much of Hwy 3 north of
Weaverville. The deterministic NAM and GFS continue to hold on to
this solution, with both showing several inches of snow in
Weaverville. Decided to upgrade to a winter storm warning above 3000
feet for primarily Highway 3 in the Trinity Horn. Advisory level
snowfall (up to 5 inches) is possible along the 299 corridor from
Oregon Mtn to Buckhorn...and a couple inches of very wet, slushy
snow are possible down to Weaverville and around Clair Engle, with
the best chance for lower elevation snowfall during the early
morning hours of Saturday. Latest guidance is showing more
pronounced warming by midday Saturday, and this is expected to
switch the precip type at most of the lower elevations by Saturday
afternoon, limiting snow accumulations.

Dry weather is generally expected Sunday and Monday, although there
may be some lingering showers Sunday morning in the coastal
counties. The next chance for rain is expected on Wednesday. There
is still a lot of uncertainty on the strength and timing of this
system, but the most of the ensembles are showing it to be much
weaker than the Friday and Saturday system. MKK/TDJ

&&

.AVIATION...Mid-level ceilings and VFR conditions have prevailed
throughout the day with isolated showers periodically appearing at
coastal terminals. A dominant area of high pressure offshore has
been steering a broad shield of overrunning high level cloud cover
into the region. This cloud layer should keep temperatures from
dropping to their dewpoints overnight, although light valley fog is
still a possibility for UKI early Friday morning. Upper level
moisture advection will continue to drop ceilings overnight to MVFR
conditions and will produce periods of light rain through the day
Friday at CEC and ACV. This is only a precursor to a larger system
set to impact the PNW late Friday and early Saturday. Rainfall will
gradually become heavier late Friday night into Saturday as a large
plume of moisture makes landfall as an AR. Significant precip totals
and LLWS are likely with this system, especially on Saturday.

&&

.MARINE...Seas will continue to diminish tonight and through the day
on Friday, briefly dropping below 10 ft as westerly winds subside.
Broad upper level ridging and an offshore high will limit the
precipitation produced from a disturbance passing over the region
tonight into Friday. Winds will gradually shift southerly and
strengthen Friday afternoon and evening ahead of a more potent low
descending into southern Canada and the PNW. Very heavy rain and
potentially gale force southwest wind gusts associated with this
system are expected during the day on Saturday. Higher wind speeds
are possible depending on the strength of a coastal low level jet
developing along the OR/CA coastline, although models are still
inconsistent. Wind wave response and a long period NW swell will
cause wave heights to build again late Saturday into Sunday, with 14-
16 ft seas possible in the northern outer waters as winds subside
and shift northerly. Widespread ridging and a quieter weather
pattern is likely for the eastern Pacific early next week.

&&

COASTAL FLOODING...The highest tides of the month are coming up
Friday with 8.4 feet above MLLW. Northerly winds today are
limiting the surge over the astronomical tides, but it still may
be close to 8.8 feet and could cause some minor flooding in King
Salmon and the Arcata Bottoms. Winds are expected to become
southerly on Friday and Saturday, potentially causing Humboldt Bay
see some water levels slightly over the astronomical tides. As a
result, this may bring water levels higher than they were today
in Humboldt Bay.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Winter Storm Warning from 4 PM Friday to 9 PM PST Saturday
     for CAZ107.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 10 PM PST this evening for
     PZZ450-455-470-475.

     Small Craft Advisory from 3 PM Friday to 3 PM PST Saturday
     for PZZ450-470.

     Small Craft Advisory from 3 AM to 3 PM PST Saturday for
     PZZ475.

&&

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https://www.weather.gov/images/eka/zonemap.png