474
FXUS66 KEKA 120701
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1201 AM PDT Sat Jul 12 2025

.SYNOPSIS...High pressure has built in bringing hot weather to the
interior. This heat is likely to last the weekend into early next
week. Smoke and haze remains possible from nearby wildfires. There
is a slight chance for isolated dry thunderstorms Sunday afternoon
in northern Trinity County.


&&

.DISCUSSION...High pressure has built into the area, bringing a
shallow marine layer with dense fog at times along the coast and hot
weather to the interior. Smoke from the Butler and Green fires
remaining in the valleys will likely pool back in overnight.
Smoke models are showing the Trinity and Klamath River valleys
with high smoke concentrations overnight with general haziness is
possible across the area.

As for the heat, high temperatures between 100-110 are possible,
with the highest temperatures likely in Trinity County along the
Trinity River Valley. Widespread haze may bring highs slightly below
what is forecast, but no major impact to temperatures are likely.
The overnight lows may actually be a few degrees warmer than
forecast (forecast being low to mid 60s) in the valleys as denser
smoke could trap some heat the valleys. Regardless, this heat does
bring Moderate to Major HeatRisk and is dangerous to those without
proper cooling and those sensitive to heat related illness.

Sunday, the upper level ridge begins to move east slightly. This
could support a slightly deeper marine layer and temperatures a
degree or two lower in interior Del Norte and southern Humboldt.
Still, temperatures will remain hot. Models are picking up a
moisture intrusion from the east by Sunday afternoon. CAMs within
range are showing a low chance (15%) for some activity in northern
Trinity County. Model soundings do show a weak capping inversion
and moisture remains limited, so confidence remains low.

Monday, the ridge continues to push further east, which will
allow the marine layer to gradually deepen early next week.
Triple digit temperatures are likely to continue into at least
Monday, with "cooling" finally arriving by Tuesday and Wednesday.
Temperatures are likely to remain warm, with 90s expected for much
of the interior through the end of next week.


&&

.AVIATION...A shallow marine layer has developed around the Humboldt
Coast, mostly around Humboldt Bay and in the Eel River Valley.
Southerly reversal winds have developed along the Humboldt and
Del Norte coasts very early Saturday morning. MVFR to IFR ceilings
have developed at KACV and periods of coastal stratus may occur
around the Del Norte Coast, but probabilities are low. Gusty
northerly winds are expected again Saturday with VFR conditions
around KUKI.


&&

.MARINE...A tight coastal pressure gradient continues to produce
strong northerly winds. Gale gusts are likely in the outer waters
with gusts 40 to 45 knots possible in the northern outer waters
(PZZ470) through Saturday. Steep and hazardous wind driven seas 12
to 16 feet expected in the outer waters. Near gale winds and steep
seas 8 to 10 feet have already been observed on buoys - these
conditions may propagate into the northern inner waters, especially
nearshore of Point Saint George and Cape Mendocino. Gale gusts and
steepest seas expected to retreat to the northern outer waters late
Saturday into Sunday. Winds and seas will still remain elevated in
the southern outer waters, with the southern inners waters slightly
sheltered from the strongest winds and waves. Gale conditions and
steep seas expected to persist through Tuesday before finally
showing signs of diminishing by midweek.


&&

.FIRE WEATHER...Building high pressure along with offshore flow has
brought warming and drying to the interior and near-coastal areas.
Afternoon RHs remain very dry, into the teens and 20s across most
the interior. High elevation areas (above 2000-2500 ft or so)
continue to see moderate to poor overnight RH recoveries. Lower
elevations are largely seeing moderate to good overnight recoveries.
Offshore winds in the higher terrain are forecast to remain breezy
overnight, especially in Del Norte county, though at least Sunday
morning. Some marginal improvement is possible Sunday and Monday
nights, before finally easing by Tuesday night.

Upper-level moisture arrives from the east Sunday and Monday
afternoons. Elevated instability along with some moisture brings a
slight chance (10-15%) for isolated dry thunderstorms to northern
Trinity County. As of now, moisture looks more limited on Monday,
but there is still a 5-10% chance for isolated dry thunderstorms.

The ridge begins to weaken Monday into early next week, which will
slowly deepen the marine layer into the middle of next week. RHs
will improve in the near-coastal areas with moderate to good
overnight recoveries possible in the highest terrain by the Tuesday
or Wednesday. JB


&&

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

     Extreme Heat Warning from 11 AM Saturday to 11 PM PDT
     Monday for CAZ102-105.

     Heat Advisory from 11 AM Saturday to 11 PM PDT Monday for
     CAZ106.

     Extreme Heat Warning until 11 PM PDT Monday for CAZ107-108.

     Heat Advisory until 11 PM PDT Sunday for CAZ110-111-113>115.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Hazardous Seas Warning until 11 AM PDT Saturday for PZZ450.

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