Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 180011

National Weather Service Eureka CA
411 PM PST Tue Jan 17 2017

.SYNOPSIS...A series of storms will bring periods of rain, gusty
winds and mountain snow through the weekend.


.Short Term (through Thursday)...A strong cold front is shown off
the coast in the water vapor imagery. This has started to bring a
few light showers to the area this afternoon. The rain and wind is
expected to pick up across the area tonight as this front moves
into the area. There is still some discrepancies with the timing
of the front. The NAM is slightly faster than the GFS. For now
have tended to go more with the GFS timing. The strongest winds
are expected to be with front. Gusts 45 to 55 mph are expected
along the Del Norte coast and over the higher terrain of Humboldt
and Del Norte county. A few gusts to 45 mph are expected on the
Humboldt coast. Gusts to 40 mph are possible in northern and
coastal Mendocino county. The rain is expected to be heavy for
much of the morning and early afternoon as the front moves. This
may cause some small stream flooding and street flooding. Some of
the rivers are expected to reach monitor stage, but the duration
is not expected to long enough to cause significant flooding. For
most of the area snow levels are expected to be high, however this
looks like a situation where there will be cold air persisting
over the valleys of eastern Trinity county. Went ahead and
upgraded the watch to a warning. For now it looks like most of the
low elevation snow will be north of Douglas City and east Oregon
Mountain in Trinity County. Kept the warning level at 3500 feet
expect there will be 6 to 8 inches with higher amounts possible.
An inch or two is possible as low as 2000 feet especially later
Wednesday night. For now it looks like snow levels will remain
above 4500 feet elsewhere, but confidence is low on these levels
and this will need to be watched closely.

Thursday showers will taper off and it is expected to be a mainly
dry day. Skies are expected to remain fairly cloudy through much
of the day. MKK

.Long term (Thursday night through Tuesday)...The next system
starts to move into the area Thursday night. Snow levels for the
majority of the precipitation will be 3500 to 4000 feet. A winter
storm watch may be needed at some point. This would impact Hwy 36
and Highway 3. Current models Friday afternoon and Friday night
snow levels will falling to around 2000 to 2500 feet although snow
amounts are expected to be fairly light. Showers will taper off
Saturday. Late Saturday night into Sunday the next system moves
into the area. The heaviest rain is expected in Mendocino county
with Humboldt, Del Norte, and Trinity counties on the cold side of
the system. This has the potential to be a significant snow event
if the models remain consistent. MKK


.AVIATION...Conditions will gradually deteriorate from north to
south over the next 24 hours, as ceilings light rain overspreads
the region,causing ceilings and visibilities to lower. Some of the
rainfall may be moderate to briefly heavy for short periods of
time. However, confidence in timing this and the duration of such
wasn`t high enough to include more that a light precipitation
intensity at this time.

The other main concern for KCEC and KACV will be low-level wind
shear. A strong 850mb jet, with wind speeds in excess of 60 knots,
will be passing by to our north, yet be close enough that wind
speeds of at least 45 knots are likely in the lowest few thousand
feet. As such, sufficient vertical speed shear exists for wind shear
to be mentioned in the TAFs. The latest VAD wind profiles from the
KBHX Doppler radar west of Fortuna, and the profiler near KACV
confirm that wind shear is near current forecast values and
increasing. /PD


.MARINE...A strong area of low pressure across the coastal waters
of the Pacific Northwest and an associated strong low-level jet
cause surface winds to increase significantly over the next 24
hours. The strongest winds will be north of Cape Mendocino across
the outer and inner waters, where some gusts could approach or
exceed storm fore criteria. However, duration and coverage of such
remains in question, and for now will keep the current headlines
in place, Gale force conditions will develop from north to south
across the waters through this time period this evening through
tomorrow. After which time, conditions will improve to small craft
criteria by wednesday evening.

The strong winds described above will also allow seas to build
into the 15 to 20 feet range. As the first system departs the
region, a second system for the end of the week will cause seas
to build towards 30 feet. /PD


CA...Wind Advisory from 7 PM this evening to 11 AM PST Wednesday for

     Wind Advisory from 10 PM this evening to 11 AM PST Wednesday for

     Wind Advisory from 10 PM this evening to 1 PM PST Wednesday for

     Winter Storm Warning from 10 AM Wednesday to 4 AM PST Thursday
     for CAZ107.

NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 3 AM PST Wednesday for PZZ450-475.

     Gale Warning from 3 AM to 3 PM PST Wednesday for PZZ450-475.

     Small Craft Advisory until 3 PM PST this afternoon for PZZ470.

     Gale Warning until 3 PM PST Wednesday for PZZ470.

     Small Craft Advisory from 9 PM this evening to 9 AM PST
     Wednesday for PZZ455.

     Gale Warning from 9 AM to 3 PM PST Wednesday for PZZ455.



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