Small Craft Advisory 102, NWS Eureka, CA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
243 PM PDT Thu Sep 28 2023

.SYNOPSIS...A weak frontal system will approach the area from the
northwest tonight, bringing widespread, mostly light rain to the
area. Lingering interior showers are expected on Saturday. Rainfall
amounts will generally range from a half inch in the north to less
than a tenth in the south. Dry weather is forecast to return Sunday
persisting into next week. Temperatures will be near normal through
the weekend, with warmer conditions next week.

&&

.DISCUSSION...Low clouds and fog lingered across many interior river
valleys this morning, and this kept even the normally colder
locations mostly in the 40s and prevented frost formation. Inland
clouds rapidly dissipated with daytime heating today, and early
afternoon skies were sunny across most of the area. Some mid-level
cloudiness will spreading SE across the OR/CA border, and more clouds
are expected to spread into the area and gradually lower this
evening. Light rain is forecast to reach the North Coast by around
midnight tonight, then continue to spread SE.

The upper trough over the Pacific NW is forecast to amplify as
shortwave energy digs southward into the base of the trough tonight
and Friday. At the surface, a 1008 mb low is progged to develop and
move SE toward the extreme SW OR and NW CA coast on Friday. Rainfall
amounts with this system are expected to be mostly light through
Friday night, ranging from around a half inch over the terrain of Del
Norte County to less than a tenth of an inch across S Lake County
and portions of Mendocino County.

The NBM has at 15% probability of thunder over portions of the
interior for Saturday afternoon. The available CAPE is forecast to
be low (100-200 J/kg in most locations) and fairly shallow. Still, a
thunderstorm or two may develop over the high terrain during the mid
to late afternoon, and have included isolated thunderstorms in that
area. Any shower or thunderstorm activity will drift SW but will
likely weaken rapidly once displaced from the ridgetops.

The remainder of the forecast period is forecast to be mostly dry,
with near normal temperatures into Monday. Temperatures are forecast
to trend warmer by next Tuesday and Wednesday as an upper ridge
noses E from the E Pacific. /SEC

&&

.AVIATION...Patchy stratus/fog developed along some coastal areas;
conditions were likely more impactful at CEC as brief periods of
CIG/VIS IFR were reported. Elsewhere along the coast, conditions were
VFR except for some haze reported at ACV. This morning, widespread
inland river valley fog was observed across all counties. However,
UKI remained clear. VFR is expected to prevail at all TAF terminals
through at least late tonight before RA/SHRA approach the far North
Coast. ACV and CEC coastal terminals can expect conditions to worsen
as the overnight weather system advances. MVFR/IFR visibility and
ceilings are likely by late morning at the coast. /TA

&&

.MARINE..N winds will start to diminish late tonight and shift to
southerly over the northern waters by early Friday morning in
advance of another frontal system. Northerlies will redevelop late
Friday and increase across the waters into the weekend as the
pressure gradient tightens over the area. Gale force northerlies are
forecast across the outer waters on Saturday. A Gale Watch continues
for the outer waters. In addition, steep to very steep seas around 10
to 16 feet will build with the increasing winds across the outer
waters. Conditions are expected to gradually improve late Sunday
through Monday. A long period westerly swell will build on Monday and
may bring an increased risk of sneaker waves. /ZVS&SEC

&&

.FIRE WEATHER...NW winds will become gusty this afternoon and evening
across Mendocino and Lake counties. This will coincide with some
fairly low interior relative humidity values to produce a marginally
increased risk of fire spread. This is in an area that has received
minimal rainfall with the past couple of systems, and the headline
for fire wx zones 264, 277, and E 276 will continue through the
evening. More gusty northerly winds are expected late Friday into
Saturday night. However, both minimum humidity values are forecast to
be fairly high. /SEC

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 AM Friday for PZZ455-475.
     Small Craft Advisory until 3 PM this afternoon for PZZ470.
     Gale Watch from late Friday night through late Saturday night
      for PZZ470-475.

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