Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 222232
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
232 PM PST Thu Feb 22 2018

.SYNOPSIS...Light snow showers will taper off this evening, but
very cold temperatures may result in icy roads overnight tonight
and Friday morning. Dry but cold weather is expected Friday, with
another round of weak showers and snow showers is expected early
Saturday. A more substantial system will bring rain and snow on
Monday.

&&

.DISCUSSION...

..THURSDAY NIGHT THROUGH SATURDAY NIGHT...Snow showers are
quickly weakening throughout the region this afternoon, leaving
only a few very light showers clinging to some interior hills.
While some of these more persistent showers rooted to the terrain
may result in a quick dusting of snow before the end of the night,
most accumulating snow and the potential for small hail has
ended. However, while roadways are improving, some snow may linger
in shady spots and and high elevations through the night.
Meanwhile, overnight low temperatures are expected to be
exceptionally cold, likely dropping well into the teens and low
20s across the interior, and the mid to upper 20s all the way out
to the beach in some places that are sheltered from gusty
northwest winds. As a result, icy patches are a near certainty
overnight, and a Hard Freeze Warning has been issued for coastal
areas from tonight through Friday morning. And as for those winds,
some exposed coastal areas and ridges can expect to see wind
gusts to around 35 mph through the evening and early overnight
hours as well.

 Dry but chilly conditions can be expected Friday as dry air and
a brief period of high pressure moves over the area. Some valley
fog may linger in interior areas as well, which could contribute
to icy road surfaces where it persists.

 A weak storm system will move through the Pacific northwest and
into the Great Basin early Saturday, and drag a weak cold front
through northwest California as it does. As a result, another
round of weak showers will impact mostly Del Norte, Humboldt, and
Trinity counties early Saturday. While the airmass will be cold
yet again, it will likely not be quite as cold as the most recent
event, and showers will likely not be as strong or numerous. As a
result, while some light and low elevation snow accumulations will
be possible, amounts will likely be less than what we saw today.
/BRC

&&

.AVIATION...Northerly gales today will result in a large and
steep sea state through early Friday morning. Afternoon buoy
observations showed extremely steep waves northward of Cape
Mendocino. We expect steep waves to build across the southern
inner waters too as stronger winds shift southward tonight. As a
result, hazardous seas warnings were added to the inner waters
through tonight. Then as high pressure causes the gradient to
relax, north winds and steep seas will gradually subside through
the weekend. A northwesterly swell, however, will continue to
impact the waters through next week helping to keep seas somewhat
elevated. Once gales expire early Friday morning, any wind gust or
sea hazards look to be marginal but we will have to examine the
potential for perhaps a low-end small craft advisory over the
weekend. The next period for more obvious deterioration in the
marine environment will come in the wake of a storm system early
next week. During this period north winds will ramp up and a large
swell will impact the waters. Expect near gales and combined seas
near 11 to 16 feet potentially on Monday through early Tuesday
morning. Confidence has been increasing with the impacts of this
storm system but please stay tuned for possible timing changes.
/KML

&&

.MARINE...Looking into the extended forecast, longwave models
predict broad troughing across the western United States to
persist through much of next week. This system will harbor a cold,
polar airmass which will generally keep temperatures slightly
below normal. This pattern will also allow embedded upper-level
shortwaves to bring additional opportunities for rain and lower
elevation snow. The first of which will impact on Sunday with the
heavier band of precipitation by late Sunday night as the cold
front passes overhead. Impactful snow accumulations will be
possible as snow levels fall through Sunday night but an
additional concern will be snow showers (possibly low elevation)
impacting those traveling/commuting on Monday morning. Confidence
is increasing with this system with another round of wintry
impacts that will potentially make traveling hazardous. Stay tuned
for updates with this system. Shortwave ridging will bring a
brief break from precipitation for most of Tuesday before another
round of wintry weather conditions arrives through the later half
of next week. Both the GFS and ECMWF are hinting at greater
precipitation accumulations and low snow levels but there are
still discrepancies in the timing and positioning of this late-
week storm system. /KML

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...Hard Freeze Warning from 10 PM this evening to 9 AM PST Friday
     for CAZ101-103-109.

     Winter Weather Advisory until 4 PM PST this afternoon for CAZ102-
     104>108.

NORTHWEST CALIFORNIA COASTAL WATERS...Gale Warning until midnight PST tonight for PZZ470.

     Small Craft Advisory until 3 PM PST Friday for PZZ455.

     Hazardous Seas Warning until midnight PST tonight for PZZ455.

     Small Craft Advisory until 3 AM PST Friday for PZZ450.

     Hazardous Seas Warning until midnight PST tonight for PZZ450.

     Gale Warning until 6 AM PST Friday for PZZ475.

&&

$$

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