Heat Advisory 2, NWS Eureka, CA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
302 PM PDT Sun Jun 9 2024

.SYNOPSIS...Isolated thunderstorm possible over the northeastern
portion of Trinity County this afternoon. Hot temperatures will
rapidly build on Monday with moderate heatrisk for many interior
valleys...locally major heatrisk in Lake County, Tuesday and
Wednesday. Breezy north to northwesterly winds will return
Tuesday and Wednesday, with the strongest gusts over the coastal
headlands and exposed ridges.

&&

.DISCUSSION...GOES-West satellite imagery shows a weak upper level
trough continuing to eject eastward away from the west coast this
afternoon. Temperatures are running 2 to 6 degrees cooler across the
interior compared with yesterday's reading. Stratus eroded to the
coast and mixed out as northwesterly breezes increase this
afternoon to bring a period of sunshine. However, onshore flow
will push back inland the stratus later this afternoon and
evening. The marine layer is expected to slightly deepen once
again tonight into Friday.

Some elevated instability has been occurring across the interior
portion of the area today, mainly over Trinity County around the
Alps and Yolla Bolly. Cumulus has been developing with daytime
heating, however most model soundings depict a cap that could
inhibit convection over most of our CWA this afternoon.
High- resolution guidances remain the primarily activity to the
northeastern portion of Trinity County this afternoon into evening.
National blend of model indicates there is a 10-15% chances for
isolated thunderstorm in the aforementioned area.

High pressure will quickly build over the West Coast in the wake of
the trough with 850 mb temperatures warming. This will bring a
warming trend early this week, with Moderate HeatRisk returning
across the interior valleys on Monday and continue through mid week.
Interior high temperatures in the mid 90's into low 100s are
expected to return across across the warmer locations of Trinity,
Lake, interior Mendocino, and northeastern Humboldt. The heat is
forecast to peak on Tuesday with locally major heat risk in Lake
County.

Additionally, a thermal trough is expected to develop near the coast
Wednesday. This will promote breezy north-northwesterly winds each
afternoon Tuesday and Wednesday over the exposed ridges and
coastal headlands, with gusts from 25 to 35 mph at times...locally
higher gusts possible over the King Range and Crescent City. NBM
probabilities shows a 80% to near 100% for gusts of 40 MPH or more
in the King Range, and 45% chances for Crescent City.

Another trough in westerly flow will knock down the ridge toward the
latter portion of the week; Thursday-Saturday and high temperatures
will once again trend down to around seasonal averages. Chance for
any rain toward the end of the week or next weekend is quite low,
less than 10% near the Oregon border. / ZVS

&&

.AVIATION...A short-lived marine layer has mixed out of KCEC and
KACV terminals leading to clear sky and northwesterly, onshore flow
through the afternoon with possible gusts as winds flow around a
weak thermal trough in the central valley. These onshore winds have
the potential to carry sea spray and other aerosols that will create
some hazy conditions, possibly bringing down visibilities and
leading to some ghost cloud layers registered on METARs. Later
tonight however, as a high pressure system approaches out area,
model guidance is showing a high possibility (50-70% according to
NBM) of the marine stratus layer returning. This layer will
actualize as broken to overcast skies overnight into about midday
tomorrow morning with locally limited visibilities caused by mist
suspended in the air. If and when this low cloud layer forms, it is
forecasted to mix out by the afternoon as onshore winds return to
the coastal terminals. At KUKI, the story is entirely different.
Currently there are clear skies with north winds and gusts reaching
up to 20 or so knots. These winds will die off after sunset tonight
and calm conditions should prevail. A surge of moisture is
forecasted to start creeping up the Russian River valley around this
time as well, however that cloud layer is not currently forecasted
to make it up to Mendocino Co and should retreat before reaching
Cloverdale. DS

&&

.MARINE...Wave heights have been slowly climbing as a moderate
long period westerly swell fills into the waters. Seas are further
enhanced by gusty northerly winds developing in the outer waters
and lee of Cape Mendocino, near or just reaching gale gusts in the
southern zones. Steep seas approaching 10 feet and gusty
northerlies will persist through Monday, with a brief reprieve
expected on Tuesday as the coastal jet shifts slightly offshore
and into the southern waters. Winds are forecast to quickly
increase late Tuesday into Wednesday, producing widespread gales
and steep and hazardous seas, especially in the outer waters.
Responsive wave heights approaching 15 feet are possible late
Wednesday into Thursday as the gales persist. Inner waters may
experience slightly subdued conditions, but waves should still be
well within advisory criteria.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 PM PDT Monday for PZZ450.

     Small Craft Advisory until 3 AM PDT Tuesday for PZZ455-470.

     Small Craft Advisory until 3 PM PDT this afternoon for
     PZZ475.

     Gale Warning until 9 AM PDT Monday for PZZ475.

&&

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