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Area forecast discussion 
National Weather Service Eureka California
421 am PDT sun Aug 30 2015

Synopsis...light showers will develop in northern Humboldt and
del norte counties this morning and persist until early afternoon.
Temperatures will remain generally below normal for the next
several days as a trough sits over the West Coast.


Discussion...the forecast for the near term appears to be on
track as the weekend draws to a a weak cold front
continues to move closer to the Redwood coast. Satellite imagery
reveals that the axis of a potent upper trough remains just
offshore...and cooling cloud tops appear to indicate that stronger
lift is spreading into the area. The timing of these features
appears to line up well with high resolution model
guidance...which is generally in agreement that a narrow band of
light to moderate rain will move onto the Redwood coast around 5
am and gradually dissipate through the morning and early afternoon
as it moves farther onshore. As of 315 only very light radar
returns are visible across the waters...but coverage does appear
to be gradually increasing and this trend is expected to continue.
While rain totals will be generally light...some areas in the
hills of del Norte County could see a quick third of an inch or so
this morning...with quickly tapering totals as you head farther
south. In Humboldt County...rain totals will likely range from a
maximum of a couple tenths of an inch in the Northern Hills to
only a couple hundredths in the central and southern portions of
the County. Very little...if any...precipitation is expected to
make it as far inland as Trinity County and as far south as
Mendocino County. Showers should be mostly dissipated by middle
afternoon...revealing mild afternoon temperatures and gradually
clearing skies.

For the remainder of the work week...the West Coast will remain
under the influence of a longwave trough...with multiple smaller
scale shortwaves rotating around it through the Pacific northwest.
While this unsettled pattern will keep interior temperatures
pleasantly mild and below normal for early September...a generally
dry airmass will likely limit the potential for meaningful
rainfall in northwest California. Best chances for any additional
rain will likely be in our northern areas where weakening cold
fronts moving through the Pacific northwest could clip our
area...particularly from middle to late week...but either way wetting
rains seem unlikely. /Brc


Aviation...light rains associated with an approaching shortwave
trough and attendant surface front are beginning to show up on radar
in the offshore waters. Low ceilings continue at kcec...and
ceilings should begin to drop at kacv over the next few hours.
Conditions will improve during the afternoon hours. Appears to be
some low cloudiness to the SW of kuki and light S winds are being
reported to the S. Will continue to watch for encroachment on the
Airport. Winds will be generally light across the area. /Sec


Marine...winds have continued to diminish across the coastal
waters...and the offshore Small Craft Advisory was allowed to
expire at 3 am. Short period SW waves will subside this morning. A
long period northwest swell is presently moving into the waters with
periods near 20 seconds and heights around 3 feet. There will be a
narrow window for a sneaker wave threat this afternoon and early
this evening when short period SW waves subside and northwest swell has
yet to ramp up. Believe the threat is moderate at best and is
currently well handled in the hazardous weather outlook. The
aforementioned northwest swell will build to 6 to 7 feet at periods of 11
to 12 seconds. Light to moderate north-northwest winds will return early in
the coming week with short period northwest seas becoming gradually more
dominant especially in the S offshore waters. /Sec


Fire weather...a weakening cold front is currently in the
process of moving onshore as of 330 this morning...and this is
expected to result in a period of light rain across primarily del
norte and northern/coastal portions of Humboldt County from
approximately sunrise until noon. Best chances for wetting rain
will be across the mountains of del Norte County where rainfall
totals of up to a third of an inch will be possible. Totals will
decrease quickly farther south and inland...with totals ranging
from only a few hundredths of an inch to perhaps a couple tenths
of an inch in northern portions of Humboldt County.
Otherwise...mild temperatures and high humidity will persist
through the day...with gradually decreasing wind gusts along
ridgetops. Light to moderate north to northeast offshore flow is
expected to develop overnight...but cool temperatures should
continue to allow for good recoveries.

While a brief...muted warmup can be expected Monday
afternoon...cooler than normal temperatures will continue for the
remainder of the work week across northwest California...which
will in turn help to keep humidity levels somewhat high. One thing
to watch will be the arrival of very dry middle level air...which
models indicate will begin to move through the area from the
northwest beginning Monday afternoon. While valley locations will
likely remain sheltered from this dry air...some of the ridge
tops and middle slopes will likely see a drying trend Monday night
and Tuesday. Fortunately winds are expected to remain generally
light through this period...and temperatures will remain near to
slightly below normal.


Eka watches/warnings/advisories...
Northwest California coastal waters...none.


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