710
FXUS66 KEKA 071259
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
435 AM PDT Mon Oct 7 2024

.SYNOPSIS...High temperatures begin to trend downward today as
high pressure weakens. Coastal stratus likely to return this
evening. Rain possible late week.


&&

.DISCUSSION...High pressure has begun to move out this morning,
starting a gradual cooling trend down to fall-like temperatures
by midweek. Temperatures do still remain warm today, only falling
a few degrees, with low to mid 90s possible across most interior
valleys. Mid-level moisture from the SW continues to bring spotty
cloud cover across Mendocino and Lake Counties today. Radar is
picking up reflectivities in the waters early this morning that
will make their way toward shore. Rain is not expected as surface
conditions remain dry, likely evaporating any rain before reaching
the surface. A stray sprinkle is not completely out of the
question, however.

High pressure moving out also disrupts the offshore wind pattern
that has kept widespread coastal stratus away for much of the
last week. As offshore wind subsides, stratus and fog will likely
form and impact much of the coast. A weak shortwave moving
through Tuesday night into Wednesday looks likely to bring in
more moisture, rebuilding or reinforcing coastal stratus, and
perhaps bringing drizzle to coastal Humboldt and Del Norte.

A stronger upper level low is forecast to move through Friday
and Saturday. NBM shows a 70 percent probability of wetting rain
(>0.1 in) for much of Humboldt and Del Norte Counties and 50 to
60 percent for much of Trinity, Mendocino, and Lake Counties. The
chance for an inch of rain is around 50 to 60 percent for Humboldt
and Del Norte Counties. Gusty southerly wind on ridges and
coastal headlands are possible with this system, though details
are uncertain and NBM probabilities of peak gusts greater than 30
mph are currently low. More details of this system will become
clearer in the coming days. JB


&&

.AVIATION...Radar imagery over the waters reveals some light
showers associated with a weak passing shortwave. The showers are
not expected to hold together over land, with only mid level
clouds streaming in through the afternoon. Offshore flow on Sunday
effectively dried out the boundary layer, and clear skies and VFR
conditions prevail as a result. Low level moisture will be on the
increase with a shutdown of the offshore flow and moistening
westerly flow. This will result in a building offshore marine
layer throughout the day. Coastal stratus may threaten close to
the coastal terminals by this afternoon before chances
significantly increase this evening. This layer looks to be
shallow, and NBM chances for LIFR CIGS increase to 46% along the
coast around 2Z to 4Z Tuesday. Fog development also looks probable
with HREF and NBM highlighting 35 to 50% probability for VIS 1
mile along the coast.


&&

.MARINE...A northerly wind pattern continues, with the main focus
south of Cape Mendocino. The winds in the southern waters will gust
in excess of 25 kts. Short period seas will respond to these winds
today, building 6 to 8 ft in the southern zones. There will be a
short uptick of steep seas up to 6 ft across the northern outer
waters late this morning through this afternoon. A small, long
period WNW swell is building through the waters this morning with a
period of 16 to 18 seconds. The swell will build this afternoon to
the 6 ft range. Winds and short period seas will be low for the
northern inners creating a sneaker wave risk. Otherwise, a very
similar wind pattern will carry through Tuesday. The northerlies
look to increase in coverage late Wednesday before an approaching
trough weakens the northerlies Thursday. Southerly winds will likely
increase with this trough on Friday. NBM has a high probability of
wind gusts greater than 25 kts from the south at this time. The
dynamics of the trough may support stronger gusts.


&&

.FIRE WEATHER...Temperatures are forecast to cool by a few degrees
today, but minimum RHs remain in the teens and 20s with poor to
moderate recoveries. Gusty westerly wind is forecast to increase
this afternoon, peaking around 20 to 25 mph in exposed areas of
southern Mendocino and Lake Counties. Elevated to locally critical
fire weather conditions are possible this afternoon and evening
as winds increase. Conditions improve in the coming days as
temperatures trend downward and RHs trend upward. Wetting rain is
possible Friday and Saturday across much of the area. JB


&&

.BEACH HAZARDS...A long period WNW swell will is building in this
morning with a period of 16 to 18 seconds. The swell will peak this
afternoon through this evening at around 6 ft. Light winds and a
lack of shorter period seas north of the cape will heighten the
sneaker wave risk Monday. Avoid steep beaches, climbing rocks,
jetties and outcroppings. Never turn your back on the ocean.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Beach Hazards Statement from 8 AM PDT this morning through
     this afternoon for CAZ101-103.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 3 PM this afternoon to midnight
     PDT Tuesday night for PZZ455.

     Small Craft Advisory from 9 AM this morning to 4 PM PDT
     this afternoon for PZZ470.

     Small Craft Advisory from 9 AM this morning to midnight PDT
     Tuesday night for PZZ475.

&&

$$

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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png