Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 242340

National Weather Service Eureka CA
340 PM PST Fri Nov 24 2017

.SYNOPSIS...Dry weather will persist through late tomorrow before
another storm system spreads rain our way. Windy and wet conditions
will prevail through Monday. Drier weather returns late Monday and
will remain through the end of the week for most locations.


.DISCUSSION...Tomorrow, the first storm system will begin
to approach the Pacific Northwest which will begin to enhance
southeast winds across Northwest California. Models have continued
to struggle with run to run consistency however models are in
slightly better agreement today than they were yesterday (at least
for the first system). Still expecting strong southeasterly winds to
begin Saturday afternoon and last through the evening. These
southeasterly winds will cause temperatures near Humboldt Bay to be
warmer due to downsloping as well as remain fairly dry through
Saturday evening. Higher elevations could see sustained winds of 40
mph with gusts near 60mph. Lower elevations along the coast could
also see some gusty winds around 30mph. These winds will gradually
diminish and switch out of the west on Sunday.

Precipitation with the first storm system has also come into better
agreement today compared to yesterday. Most models now show a plume
of moisture oriented towards the Mendocino coast and another axis of
moisture further north impacting Del Norte and points north.
Therefore have bolstered the rain amounts especially for mountains
with southwest facing slopes due to enhanced orographic lift. Rain
timing is still slightly in question however, it appears that as the
warm front approaches our area late Saturday afternoon precipitation
will begin to increase however the heavier rain should hold off
until late Saturday night into early Sunday morning. This rain
should begin to taper off late Sunday night. Most areas will see
upwards of an inch of rain however, southwest facing mountain slopes
could potentially receive upwards of 2 inches especially south of
Cape Mendocino. With this precipitation there is an increased risk
of rock and mudslides near mountainous terrain and ponding water on
the roadways, which may impact travel. The exact storm total
precipitation is still questionable due to timing and location
differences that exist between the various model runs.

Another big question is with the second system that was supposed to
move through late Sunday night and into early Monday morning however
the latest model runs have shifted that system much further south.
Also due to this further south track snow levels do not appear to
drop as low as originally thought however the higher terrain will
still have the potential for some accumulating snow IF precipitation
continues as the cold air moves in. With the further south track
instability parameters have come in more unstable with LI below 0
and steep low to mid level lapse rates. Therefore, have left a
slight chance of thunder for the waters and immediate coastline
primarily south of Cape Mendocino. With any heavier shower Sunday
night and early Monday some small hail will be possible due to the
lower freezing levels. Showers will gradually taper off Monday
afternoon returning the northcoast to a primarily dry weather
pattern for the week. Some showers are possible towards the middle
of the week across the northern waters and perhaps Del Norte county.


.MARINE...Light winds and relatively low seas will persist into
tonight as high pressure moves over the waters. A low pressure
system will begin to approach tonight turning winds S. These winds
will rapidly increase with gales likely in the outer waters by late
Saturday afternoon and continuing overnight. Very steep seas will
build in response to the winds, peaking between 10 and 15 feet early
Sunday morning. Have upgraded the existing Gale Watch to a Gale
Warning. Have also hoisted Small Craft Advisories in the outer
waters leading up to the gales in addition to advisories for the
inner waters.

Winds will decrease on Sunday after the first system moves inland
followed by a return to southwest winds once again Sunday evening.
In addition to the winds, a large northwest swell will build into
the waters on Sunday. Seas in excess of 10 feet at 14-16 seconds are
expected, potentially exceeding 15 feet in the southern waters by
Monday. Additional large northwest swells will build into the waters
later this coming week.

North winds are anticipated to return Monday through mid week. Small
craft to near gale force northerlies will be possible with the
strongest winds expected by Tuesday night or Wednesday. /RPA&SEC


.AVIATION...Multi-layered cloudiness prevailed across the area
today. Some periods of IFR ceilings occurred along the Redwood
Coast, and those continue as of this writing. Expect mostly mid and
high cloudiness overnight tonight with little in the way of
visibility reduction. Winds will begin to increase by Saturday
afternoon. /SEC


CA...Wind Advisory from 6 PM Saturday to noon PST Sunday for CAZ101-

NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory from 3 PM Saturday to 3 AM PST Sunday for

     Small Craft Advisory from 3 PM Saturday to 9 PM PST Sunday for

     Small Craft Advisory from noon to 3 PM PST Saturday for PZZ470.

     Gale Warning from 3 PM Saturday to 3 AM PST Sunday for PZZ470.

     Small Craft Advisory from noon to 6 PM PST Saturday for PZZ475.

     Gale Warning from 6 PM Saturday to midnight PST Saturday night
     for PZZ475.



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