Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 201317

National Weather Service Eureka CA
517 AM PST Wed Feb 20 2019

.SYNOPSIS...A cold front associated with a weak area of low
pressure will pass through northern California today. Showers will
impact most of our area, especially north of Mendocino county.
Light snow accumulations will make for slick travel across some of
the mountain passes. Cool and dry conditions with frosty mornings
are expected Thursday and Friday, before another round of rain and
mountain snow arrives this weekend.


.DISCUSSION...Rain and mountain snow showers will impact much of
northwest California today, before tapering off this evening. Weak
low pressure passing across the interior will push a cold front
southward, which will result in snow levels falling later today
and tonight. The current Winter Weather Advisory above 2500 feet
in Del Norte, Humboldt, and northern Trinity county still looks on
track, though some areas around 2500 feet are still seeing rain. It
is tough to get a handle on the exact snow levels early this
morning, but it appears to be generally around 2500 to 3000 feet
based on the available web cams and other observational data. Snow
levels will lower closer to 2000 feet this evening, but by then
most of the showers will be quickly tapering off and shifting
offshore, as stability increases and drier air filters in. Berry
Summit will be the most critical highway pass to see impacts, with
2 to 4 inches of snow possible by this evening. Scott Mountain
Summit and rural roadways above 2500 feet such as Bald Hills Road
may see several inches or more. Lower areas closer to 2000 feet,
and areas farther south in Mendocino county, and to the east in
Trinity county, will see only very minor accumulations. As far as
rainfall amounts go, expect around a half inch possible from
Eureka to Crescent City, which is a bit more than models were
projecting yesterday. Much lighter amounts of a tenth of an inch
or less will be occur over Mendocino county and eastern Trinity.

Skies will begin to clear late tonight as high pressure builds in,
with the last of the shower activity near Cape Mendocino or near
Siskiyou County tapering off by Thursday morning. Expect mostly
sunny skies with another cool day, as highs will run several
degrees below seasonal averages. Friday will start off frosty,
similar to Monday or Tuesday morning, but probably not quite as
cold. Clouds will begin to increase in the afternoon as the next
weak cold front approaches. Models are still not in total
agreement with the weather this weekend into early next week, but
are trending toward a more substantial series of storm systems
impacting our region from Sunday through Tuesday. Potential
mountain snow and periods of heavier rainfall appear to be the
main impacts, as there will likely be a better connection to
deeper Pacific moisture compared to the past few weather systems.
Snow levels may end up higher than most highway passes with a bit
more warm air involved, but details like that are subject to
change as we refine the forecast over the next few days. /AAD


.AVIATION...Intermittent light rain will continue for most of the
day along the Redwood coast, producing predominantly MVFR ceilings
at CEC and ACV. Conditions may occasionally improve to VFR or
briefly deteriorate to IFR at times over the course of the day.
Gusty northwest winds will also persist at the coastal terminals.
Meanwhile, UKI will also see the potential for light rain at times
during the morning but is generally expected to remain VFR. Rain is
expected to clear the area by approximately 06z, yielding widespread
VFR conditions into the overnight hours. /CB


.MARINE...Persistent moderate to strong northerly breezes and steep
short period seas will combine with a building mid period swell to
produce potentially hazardous conditions over the coastal waters
through late in the week. Opted to begin the Small Craft Advisory
for the southern nearshore waters early as short period seas around
8 feet and gusts to 25 mph have already been observed and are
expected to continue through the day. Advisory conditions are also
expected to spread back into the northern nearshore waters this
evening if not sooner. The worst conditions are expected tonight
into Thursday as winds continue to increase and the NW swell builds
to around 12 feet at 14 seconds, producing combined seas on the
order of 15 to 17 feet. Have upgraded the Gale Watch to a Warning
for the southern outer waters as gusts to around 40 kt develop by
late this evening. Winds will begin to trend downward late Thursday
as the swell also begins to decay, yielding improving conditions
through the day on Friday and into the weekend as seas gradually
subside. /CB


CA...Winter Weather Advisory until 8 PM PST this evening for CAZ102-

     6 PM this evening to 9 PM PST Thursday
     for PZZ450.

     Small Craft Advisory until 9 PM PST Thursday for PZZ455-470.

     Small Craft Advisory until 9 PM PST this evening for PZZ475.

     Gale Warning from 9 PM this evening to 9 PM PST Thursday for



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