FXUS66 KEKA 181132

National Weather Service Eureka CA
432 AM PDT Mon Mar 18 2019

.SYNOPSIS...Mild and dry conditions can be expected today through
most of Tuesday, with coastal dense fog along the coast early
Monday. Light rain can be expected late Tuesday and Wednesday,
with a quick round of moderate rain expected Friday.


.DISCUSSION...While generally benign conditions exist in most
areas of northern California this morning due to the presence of
high pressure, a summer-like shield of shallow marine stratus and
fog has developed across the waters and along the immediate coast.
Due to the shallow depth of the marine layer this fog is
primarily impacting very low elevations, generally 500 feet and
less, which limits its coverage on land. However, visibilities
have been universally low in the areas that have been impacted,
often 1/4 mile or less, including in Crescent City, around
Humboldt Bay, and along portions of Highway 101. While improvement
is expected by mid morning, fog will likely reduce visibilities
in some areas during the morning commute. Otherwise, once fog
diminishes later this morning, generally pleasant and sunny
conditions can be expected for much of the afternoon in all areas,
with the exception of some stubborn patches of stratus in coastal

On Tuesday, while conditions will remain mild and mostly dry for
much of the day, mid and high level cloud cover will steadily
increase ahead of an approaching weak low pressure system. By late
afternoon, a few light showers will even be possible across
interior high terrain, although much of Tuesday's activity will
likely be restricted to virga. Overnight Tuesday and Wednesday
morning, this low pressure system will move onshore in the
vicinity of the Bay Area and begin to separate from its parent
trough. As it does so, a surge in moisture will arrive in
Northwest California from the southeast, and shower coverage will
begin to increase throughout the area...particularly across
interior areas as downsloping offshore flow will likely cut into
rain rates in the coastal lower elevations. This light to
occasionally moderate rain will continue much of the day Wednesday
before dissipating overnight. While widespread thunderstorms are
not expected, some very modest instability may be enough to yield
an occasional lightning strike or two, especially in the
afternoon. Snow levels are expected to remain well above major
highway passes, and snow impacts are not anticipated.

While some lingering moisture may continue to generate very light
drizzly precipitation across the hills Thursday, a transient
upper level ridge between storm systems will keep most areas dry.
However, confidence is increasing that a progressive trough and
cold front will sweep through the area quickly between Friday and
Saturday morning, bringing a round of moderate rainfall to most of
the area. The fast-moving nature of this system will prevent storm
total accumulations from becoming particularly high, and as a
result only minimal rises on area rivers and streams can be
expected. The remainder of the weekend is likely to be dry as high
pressure regains control of the West Coast, with hints of another
potential storm system early to mid-week. /BRC


.AVIATION...Early morning satellite imagery showed marine stratus
over much of the coastal waters and along the immediate coast.
Both coastal terminals have experienced LIFR conditions most of
the overnight period, with visibility dropping to 1/4 mile at both
sites. This shallow stratus deck has since moved away from KACV,
but is still in the vicinity and appears to be making a possible
return over the terminal. IFR to LIFR conditions are expected to
continue along the coast through at least mid-morning before the
stratus retreats more offshore later this morning. Conditions
along the coast should improve by this afternoon, with VFR to MVFR
conditions expected. Though, should the stratus linger along the
immediate coast, IFR to LIFR conditions would be possible should
it move back over any terminals. VFR conditions are expected to
prevail across inland terminals through the TAF period. Otherwise,
cloud cover will begin to increase tonight across the area as a
weak system nears the region.


.MARINE...Generally light southerlies will persist through the
day today before increasing tonight to around 15 to 20 knots over
the southern waters. This will result in the development of
steeper wind driven waves as another westerly swell is set to
arrive tonight. Combined seas of 10 to 12 feet will be possible
over the southern waters beginning early on Tuesday. Small Craft
Advisories were issued for the southern waters from late tonight
through Tuesday night. Winds are forecast to weaken on Wednesday
before becoming northerly Wednesday night and into Thursday. Seas
will come down Wednesday through Thursday evening, dropping below
8 feet across most of the coastal waters. A larger westerly swell
will move through the waters late on Thursday and into Friday.
Combined seas will range from 12 to 15 feet starting from Friday
afternoon and persisting through most of the day on Saturday.


.BEACH HAZARDS...A long-period westerly moving through the
coastal waters will result in a moderate to high sneaker wave
threat on area beaches from tonight through Tuesday evening.
Beachgoers should use caution along area beaches and keep a safe
distance from the surf zone, as waves may suddenly wash much
farther up the beach than expected after several minutes of
relatively smaller waves.


CA...Beach Hazards Statement from this evening through Tuesday
evening for CAZ101-103-104-109.

NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory from 5 AM Tuesday to midnight PDT Tuesday
night for PZZ455-475.



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