Area Forecast Discussion
Issued by NWS Eureka, CA

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935
FXUS66 KEKA 142221
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
221 PM PST Thu Dec 14 2017

.SYNOPSIS...A cold front is forecast to move south across the
region during Friday. Very light rain will be possible with the
front over Del Norte county. Dry conditions will return during
the weekend into early next week, followed by a chance of rain
over much of northwest California Tuesday night.

&&

.DISCUSSION...An upper ridge was positioned from an area offshore
of CA north across WRN Canada. An upper trough was located west of
the ridge, and will aid in breaking down the ridge during Friday
as it moves east across the PAC NW. The southern tail of the
upper wave is forecast to move across NWRN CA Friday afternoon and
evening, and will support a small probability of light
precipitation over Del Norte county. The upper wave will quickly
pass southeast of the area during Friday night. Skies should
rapidly clear in its wake, and strong high pressure will build
southward across the intermountain west. The strengthening high
will yield moderate to strong NELY winds across area ridgetops
late Friday night through Saturday afternoon (refer to the fire
weather discussion below).

From Saturday afternoon through Tuesday morning, NWRN CA will once
again be under the influence of a mainly dry subsident airmass
associated with a broad upper trough centered west of CA.
However, model guidance shows a frontal wave moving south across
the area Tuesday afternoon/night. This wave appears to favor light
rainfall across much of the area, but will be followed by
restrengthening of the upper ridge during mid to late next week.

&&

.AVIATION...Persistent high pressure ridging will remain in place
through early Friday morning. As result, widespread VFR
conditions will basically be maintained over area
airfields/strips. The exception will be pockets of morning fog
across inland valleys and fog/haze near the immediate coast. Today
along the Redwood Coast, shallow fog/haze was widely reported.
These conditions can be expected again overnight through Friday
morning. Also at ACV today, cigs even dropped into IFR (600 feet)
due to sea spray under a light west to westnorthwest (WNW) wind. A
change feature will briefly interrupt the prolonged High on
Friday afternoon at the North Coast...and allow a weak and
"mostly" dry weather disturbance to brush across the region. This
system will possibly usher in some MVFR clouds, slight chance of
drizzle, and/or light rain to the far northern areas...specifically
CEC.

&&

.MARINE...Long period northwest swell continues to dominate the
sea state today as northerly winds remain generally moderate in
strength. Some steeper wind waves are likely more noticeable near
Cape Mendocino and also well offshore where the strongest winds
are located, but northwest swell remains the largest wave group in
the vast majority of the waters. Moderate north winds will
continue through approximately mid-day Friday, and will steadily
increase overnight Friday to near Gale strength by Saturday
morning. These increasing northerlies will result in building
steep seas throughout much of the waters. These strong winds will
continue through the remainder of the weekend before settling
early Monday. Light winds will continue Monday through the middle
of the week, allowing steep seas to settle during the first half
of the week. /BRC

&&

.FIRE WEATHER...Locally strong northeasterly offshore winds are
forecast to develop across area ridges late Friday night into
Saturday. Dead fuel moisture values have become critically dry
across portions of northwest California due to very little
precipitation during December. However, greening of live
vegetation is expected to preclude a more significant fire weather
threat during Saturday.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement until 10 PM PST this evening for CAZ101-
     103-104-109.

NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory from 3
     PM Friday to 3 AM PST Monday for PZZ470.

     Gale Watch from late Friday night through Sunday afternoon for
     PZZ475.

     Small Craft Advisory until midnight PST Friday night for PZZ475.

&&

$$

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