799
FXUS66 KEKA 110711
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1211 AM PDT Fri Jul 11 2025

.SYNOPSIS...High pressure is building and generally hot and dry
weather is expected for the next week or so. The hottest
temperatures will start in the south on Friday and fill in towards
the north on Saturday and Sunday. Northeast winds overnight on
Thursday and Friday will help to limit the coastal fog/stratus and
potentially bring warmer temperatures closer to the coast.


&&

.DISCUSSION...High pressure continues to build over the area and
hot temperatures are starting to take hold in Mendocino county.
Offshore flow tonight is expected to limit the coverage of clouds up
the river valleys and this should facilitate skies clearing on
coast.

The heat advisories start Friday afternoon in Mendocino and
Lake counties as the temperatures warm more quickly down there,
although there is quite a bit of warming in the north as well and
the argument could be made to start the advisories in Humboldt and
Del Counties as well. Trinity county warms more Saturday as this
heat continues to build. This is expected to be the start of a more
extended period of hot weather so have issued an excessive heat
warning. Sunday the ridge starts to shift east slightly and it looks
like this will allow some marine air to start to intrude on
Mendocino county and some stratus to the immediate Mendocino coast.
This intrusion of marine air is causing the end of the heat
advisory for the Ukiah and Willits forecast zones on Saturday
evening. Also on Sunday, the models are showing some increasing
moisture aloft and the potential for a thunderstorm over northern
Trinity county. For now, this only looks to be around a 10 percent
chance, so it wasn`t added to the forecast. One potential challenge
in this forecast is the presence of smoke aloft may keep
temperatures cooler than expected. Forecast confidence is hedging
that the smoke would not be sufficient to keep temperatures cooler
over a large area.

Monday the ridge continues to shift east allowing the marine layer
to start making its way north, cooling off portions of Humboldt and
Del Norte counties. There is still some uncertainty on how much of
the heat will linger in eastern Mendocino and Lake counties so the
advisories may need to be extended in those areas. Tuesday shows a
continuation of hot weather, yet it is expected to be more confined
to areas well away from the coast in Trinity county. On Wednesday,
an upper level trough approaching the area continues the slow
cooling trend, but most areas are expected to still be in the 90s.


&&

.AVIATION...A shallow marine layer continues to redevelop along
the Humboldt coast bringing LIFR/IFR ceilings and visibilities.
Northerly winds have eased for most of the area. Periods of
southerly reversal winds are possible along the immediate coast
between ACV and CEC, which would advect stratus northward.
Northerlies just off the Del Norte Coast will remain strong
through Friday morning, if strong northerlies push back onshore
near CEC early Friday morning, stratus could clear out around the
terminal. NBM is showing around a 60% chance for IFR or LIFR
ceilings and visibilities for CEC. Interior areas, including UKI,
are expected to remain clear aside from smoke and haze. Strong
northerlies on Friday afternoon will help clear the shallow
stratus that develops from coastal terminals.


&&

.MARINE...Northerly winds will continue to ramp up as a tight
pressure gradient sets up along the coast. Gale force gusts will
continue for the outer waters into Friday. Nearshore waters could
see gusts of 20-25 kts in the afternoons, but are largely insulated
from the strongest winds. A small area just off Cape Mendocino in
the southern inner waters will see gale force gusts,  as well.
Steep, elevated seas in the outer waters are likely to move into
nearshore waters Friday afternoon, bringing steep seas of 8-10 ft.
Winds begin to move further offshore Saturday, especially south of
Cape Mendocino. North of the Cape, near-gale to gale force winds are
likely to continue into early next week. High pressure begins to
break down by mid next week, which will likely ease winds and seas.
JB


&&

.FIRE WEATHER...High pressure is building and offshore flow is
expected with the warming and drying inland and near coastal areas.
Areas below the marine layer inversion, which is currently around
2500 feet, are expected to see good RH recoveries while areas above
it will be much drier and see breezy northeast to east winds. These
NE winds will bring hotter conditions to river valleys over the
weekend. This inversion is expected to lower over the next couple
days as high pressure strengthens. 850 and 925 mb winds are around
10-20mph overnight with RH recoveries around 40-50 percent on the
ridges again. Warmer dry conditions are generally expected on
Saturday, although portions of Mendocino county closer to the coast
may start to see more marine influence as the flow aloft weakens
starting on Saturday.

Smoke aloft will be pushed south from the Butler Fire. Then it will
shift more towards the west overnight and back to the east in the
afternoon when the winds become more northwesterly. The eastern
portions of the area may also see some smoke or haze from the Green
Fire north of Redding in the afternoons. This general pattern is
expected to continue over the next several days depending on how
much smoke the fires output.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Heat Advisory from 11 AM Saturday to 11 PM PDT Sunday for
     CAZ102-105-106.

     Extreme Heat Warning from 11 AM Friday to 11 PM PDT Monday
     for CAZ107-108.

     Heat Advisory from 11 AM Friday to 11 PM PDT Saturday for
     CAZ110-113.

     Heat Advisory from 11 AM Friday to 11 PM PDT Sunday for
     CAZ111-114-115.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 11 AM PDT Saturday for PZZ450.

     Small Craft Advisory until 3 AM PDT Friday for PZZ455.

     Gale Warning until 11 PM PDT Saturday for PZZ470.

     Gale Warning until 11 AM PDT Saturday for PZZ475.

&&

$$

NOTE: The full forecast discussion is now regularly issued between
10 am/pm and 1 pm/am. Additional updates will be issued as needed.

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