325
FXUS66 KEKA 142308
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
308 PM PST Thu Nov 14 2024

.SYNOPSIS...Convective showers and thunderstorms will continue to
impact the region in the wake of a strong cold front. Mountain snow
is likely in the Trinity horn as precipitation tapers off. Cooler
temperatures are expected for late this week into the weekend.


.DISCUSSION...Convective showers are still being observed across the
CWA this afternoon as the axis of a cold upper trough moves over the
region and generates instability. SPC has outlined the north coast
with a widespread risk of disorganized convective activity for
coastal areas of the PNW with 100-300 J/Kg of CAPE just offshore.
Locally heavy downpours and gusty, erratic winds are possible with
isolated thunderstorms.

Shower activity will gradually taper off overnight into early
Friday morning with the arrival of a cold, dry airmass on the
backside of the upper trough. Residual snow showers are likely to
continue in interior mountains of Humboldt and Trinity counties as
snow levels drop to 2500 to 3500 feet. Additional accumulations
of 1 to 3 inches are possible. Colder temperatures will reach
lower elevations Friday into the weekend. HREF highlights a high
probability (>75%) of widespread interior lows <32 degrees Friday
morning, with sub-40 degree temperatures (>75%) much closer to the
coast, especially in coastal counties. However, with so much
ground moisture following the recent rainfall, it is likely that
many of these valleys will develop fog as temperatures fall. The
furthest interior Mendocino and Trinity will have a chance of
falling into the upper 20`s while coastal areas hover around 40.

Conditions will clear out Friday as high pressure nudges its way
into the PNW. Northerly winds are expected to increase, with gusts
15 to 25 mph at higher elevations and exposed headlands.
Probabilities are greater for near-freezing temperatures approaching
the coast Friday night with high pressure subsidence within a drier
airmass. This may be the opportunity to formally designate a killing
freeze in the final days of the growing season for coastal Mendocino
and Lake counties.

After a brief period of ridging and warmer temperatures, mid range
models are noting another upper level trough with exceptionally cold
temperatures swinging down into the PNW. There is still
uncertainty in how deep this trough will dig into the region, but
it is likely that there will be another round of accumulating
precipitation late Saturday into Sunday. Preliminary QPF values
are 0.5 to 1.0 inches in northern Humboldt and Del Norte Counties,
tapering significantly to the southeast.


&&

.AVIATION...Showery conditions will continue to diminish into early
tonight for the terminals in Northwest California. Ridging
conditions will try to build in for tonight and tomorrow. Generally
light offshore flow tonight should aid in keeping coastal terminals
free from lower ceilings and visibilities. Northerly winds will
begin to ramp up for most terminals into late tomorrow morning
and afternoon.



&&

.MARINE...General west to northwest winds have begun to take over
the coastal waters after the passage of a weak front earlier today.
Short period seas have greatly moderated with the winds, but a now
declining northwest swell will still maintain steep seas throughout
all waters. This swell will very gradually decay through the end of
the week.

Northwest winds will continue to increase, especially south of Cape
Mendocino. Strong gusts are in all waters by Friday with gusts of 25
to 30 kts. Such winds will support steep shore period seas into the
weekend. Northerly winds will gradually weaken and pull south this
weekend with another series of fronts and associated
stronger southerly winds by early to mid next week.


&&

.BEACH HAZARDS...A large mid period swell continues to decline
with breaking waves decreasing to below 20 ft. In addition to surf,
King Tides are on track to build Friday and into the weekend.
Building north winds will tend to push water levels lower, but the
tides will build over the next couple days with high tide near 9
feet at the North Spit by Saturday. Such levels will most likely
generate minor coastal flooding in low lying areas of Humboldt Bay
such as King Salmon and the Arcata Bottoms.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 AM PST Saturday for PZZ450-470.

     Small Craft Advisory until 9 AM PST Saturday for PZZ455-475.

&&

$$

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