Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 212330
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
330 PM PST Wed Feb 21 2018

.SYNOPSIS...Light snow can be expected above 1000 feet Thursday
morning, with small hail accumulations possible at lower
elevations along the coast. Very cold temperatures can be expected
Friday morning. Additional light showers and snow can be expected
in northern areas over the weekend, with more widepsread
precipitation on Monday.

&&

.DISCUSSION...Moist onshore flow and surface heating continues to
generate very weak shower activity across the interior hills of
Humboldt and Del Norte counties this afternoon, likely resulting
in little more than a few sprinkles in low elevations and very
light snow in the hills. This activity will diminish during the
evening.

Late tonight, another similar system will drop into the region
from the north, this time with a bit more moisture and instability
associated with it. As a result, scattered to numerous showers
will move onto the Del Norte and Humboldt Coast beginning early in
the morning, bringing another round of low elevation snow and
potentially small hail. Given the timing of this system during the
early morning hours when temperatures will be at their coldest,
snow levels are expected to be notably low when precipitation
begins, likely to around 1000 feet and locally lower along the
coast, and down to most valley floors on the east side of the
first coastal ridges. As a result, many areas in Humboldt and Del
Norte counties will likely see light snow accumulations. Totals
will not be particularly heavy, likely only reaching 1 to 3
inches in most areas. However, the northwesterly prevailing flow
will likely favor central and southwestern Humboldt counties for
some of the heavier snows, as this will likely be a favored
trajectory for landfalling showers. As a result, some areas could
see 3 to 4 inches in places where multiple showers move across the
same paths. This region includes Berry Summit along Highway 299.
Snow levels will gradually rise late in the morning and afternoon,
and shower activity will diminish as well.

In the lower elevations right along the coast, small hail
accumulations are likely to occur as well. This can be just as, if
not more hazardous than accumulating snow for drivers, so please
use caution during the Thursday morning commute. Later in the day
Thursday, gusty winds can also be expected along the coast as the
cold front moves through the area.

Temperatures Friday morning are expected to be notably cold, and a
Freeze Watch remains in effect for many coastal areas. Low
temperatures in the mid to upper 20s can be expected.

After a cool but quiet day Friday, another weak system will bring
some light showers into Del Norte and Humboldt counties Saturday
and Sunday, again with relatively low snow levels. A more
substantial winter storm may bring some welcome widespread
rainfall Monday, including potentially significant snow
accumulations at higher elevations. /BRC

&&

.AVIATION...An abundance of mostly VFR level low clouds remained
over much of the forecast region today. However, a weak low
pressure center off the far North Coast generated MVFR CIGS at
CEC...and very light rain was even reported north of Klamath to
CEC. Elsewhere, including interior airports (UKI) will maintain
various amounts of clouds, but remain VFR. For the afternoon 24
hour TAF package (til Thursday 4 Pm), Another slightly more
significant weather system will slide down into the region on
Thursday. This system will bring a more noticeable impact to ACV
and CEC airports. This disturbance will also bring somewhat low
QPF rain amounts...and increased unstable showers to the Redwood
Coast. Northwest (NW) to north-northwest (NNW) winds will become
breezy to gusty and CIGS and VIS are expected to dip into MVFR for
short periods. /TA

&&

.MARINE...Northerly winds will continue to steadily increase
overnight tonight, but the strongest winds are not expected to
arrive in the waters until Thursday morning. By then, 25 to 30 kt
sustained northerlies are expected to arrive, with gusts to 40 kt
expected across the outer waters. This will result in building
steep seas, likely reaching 11 to 15 feet overall by Thursday
night. As a result, the Gale Watches for Thursday and Friday
morning have been upgraded to Warnings for the outer waters, while
Small Craft Advisories have been added to the inner waters for
the same time period. Wind speeds will gradually diminish Friday
through Friday night, allowing seas to slowly settle as well.

Over the weekend, moderate northwest winds will combine with
continuing northwest swell to maintain moderately elevated seas,
likely fluctuating between 8 and 11 feet combined. Northerly winds
will increase again early next week, and at the same time another
robust northwest swell will cause seas to build. /BRC


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...Hard Freeze Watch from Thursday evening through Friday morning
     for CAZ103-109.

     Winter Weather Advisory from 4 AM to 4 PM PST Thursday for
     CAZ102-104>106.

NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 6 AM PST Thursday for PZZ470.

     Gale Warning from 6 AM Thursday to midnight PST Thursday night
     for PZZ470.

     Small Craft Advisory from 9 AM Thursday to 3 PM PST Friday for
     PZZ455.

     Small Craft Advisory from 6 AM Thursday to midnight PST Thursday
     night for PZZ450.

     Small Craft Advisory until 9 AM PST Thursday for PZZ475.

     Gale Warning from 9 AM Thursday to 6 AM PST Friday for PZZ475.

&&

$$

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