Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 212254

National Weather Service Eureka CA
254 PM PST Sun Jan 21 2018

.SYNOPSIS...Precipitation will be diminishing through tonight. Dry
day on Monday, transition day on Tuesday. Next weather system will
impact NW California from Tuesday night through Friday. Potentially
drier weather after that.


.DISCUSSION...For today, precipitation has moved onshore. The
heaviest rainfall can be found in the hills south of Eureka and
north of Mendocino County. So far, most areas have seen around 0.5
to 1 inch of rainfall, with higher amounts in exposed windward
slopes. Moderate precipitation will be spreading south and east into
Trinity and Mendocino County late this afternoon through this
evening. Still expect wintry precipitation for Trinity County.
Snowfall rate can be heavy at times, lowering visibilities and
making travel very hazardous. The Winter Storm Warning for northern
Trinity County and the Winter Weather Advisory for southern
Trinity COunty remains in effect until 10 pm this evening. For
coastal Humboldt and Del Norte County, do expect precipitation to
taper off through this evening as the front pushes inland.

Gusty winds were also reported by stations in the area. Crescent
CIty observed a peak gust of 52 mph, while Cooskie Mountain saw a
gust of 51 mph. Wind gusts were around 40 to 45 mph in the Humboldt
Bay area. Wind advisory will remain in effect through 4 pm this

Monday will be a dry day across most of NW California as a
transitory high moves over the area. The dry weather, however,
will not last long. The next significant weather front will move
into the area, and allow the return of precipitation to the area
by Tuesday evening. There will also be southerly wind ahead of the
weather front on Tuesday. These southerly winds will have some
downslope drying component to it. DO expect a mostly dry, but
fairly warm day for Humboldt and Del Norte Coast. Do expect highs
on Tuesday to approach 60 degrees. Precipitation and wind will
then move into the area by Tuesday night, and then spread inland
during the overnight hours into Wednesday. Do expect moderate to
heavy rain will linger through Wednesday. After the weather front,
much cooler air and showers will impact NW California. Right now,
it looks interior snow will be favorable Thursday through Friday.
After that, looks like we may have drier weather returning to the

.AVIATION...A front will sag southward this evening generating
light to moderate rain and MVFR conditions for the forecast
terminals. Conditions should improve for CEC and ACV overnight while
conditions at UKI deteriorate to IFR.


.MARINE...A front will transition southward into Mendocino waters
this evening, however confidence that winds will gusts to 35 kt or
more remains low. All the models continue to indicate the boundary
weakening south of the Cape this evening. Thus will let the current
warnings for gales end around 6PM. Winds north of the Cape should
dye down quickly late this afternoon into early evening, however
seas will remain chaotic with a combination of large mid period
westerly swell and steep southerly wind waves. A small craft
advisory warning for hazardous seas will be necessary.

Winds should be tranquil on Mon, though seas will continue to be
hazardous due to a westerly swell centered near 14 seconds. This
swell should subside on Tue, bottoming out around 8 ft. This brief
reprieve probably will not last long, especially in the outer waters
and north of Cape Mendo, as southerlies start to ramp up again in
advance of the next storm.

A new storm system will impact the waters through the rest of the
week. South-southeasterly winds will likely strengthen to gale force
again by Tue night as the frontal boundary eventually moves across
the waters. We should see frontal passage on Wed along with brisk
west to southwest winds. Short period southerly wind waves will
dominate the spectrum Tue and Tue Night. The storm will generate a
fairly large westerly swell group arrives that should arrive Wed
night into Thu. The GFS wind fields continue to fluctuate around, so
the exact magnitude of the swell is still sketchy. We may start to
see a break in the active pattern toward the end of the week (Fri
that is), though seas will probably hover around 10 ft.



CA...Winter Weather Advisory until 10 PM PST this evening for CAZ108.

     Wind Advisory until 4 PM PST this afternoon for CAZ101-102-

     Winter Storm Warning until 10 PM PST this evening for CAZ107.

NORTHWEST CALIFORNIA COASTAL WATERS...Gale Warning until 5 PM PST this afternoon for PZZ450-470.

     Gale Warning until 6 PM PST this evening for PZZ455-475.



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