456
FXUS66 KEKA 130710
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1210 AM PDT Sun Jul 13 2025

.SYNOPSIS...Hot weather is forecast to continue for the interior
into early next week. HeatRisk diminishes by the middle of the week.
Unhealthy air quality due to nearby wildfires is possible. There is
a slight chance for isolated dry thunderstorms this afternoon and
evening over the mountains of northern Trinity County.


&&

.DISCUSSION...Hot weather continues in the interior, with high
temperatures between 100 and 110 likely. The highest temperatures
are likely along the Trinity and Klamath Rivers in Trinity and
Humboldt Counties. Slightly lower temperatures are found in
Mendocino as marine influence increases humidities and lowers
temperatures. This heat does bring Moderate to Major HeatRisk and is
dangerous to those without proper cooling and those sensitive to
heat related illness.

Smoke and haze models are showing higher smoke concentrations in the
valleys this morning before improving in the afternoon. Greater
instability today may help more haze to mix out and better air
qualities except immediately downwind from the fires. Models are
showing a moisture intrusion coming from the east. Moisture combined
with elevated instability may also bring a slight chance (10-15%)
for an isolated thunderstorm to northern Trinity County. Model
soundings do show a weak capping inversion and moisture remains
limited, so confidence remains low. There is a similar setup Monday
and Tuesday, but confidence is even lower (5-10% chance for an
isolated thunderstorm).

The ridge begins to move eastward Tuesday and Wednesday, allowing
for the marine layer to deepen and some relief to the hottest
temperatures. Temperatures are likely to remain warm, especially in
Trinity County, with mid to high 90s, but the consistent triple
digits are likely to end. JB


&&

.AVIATION...Shallow coastal stratus has developed along the
Humboldt and Mendocino coasts bringing IFR to LIFR ceilings to
coastal terminals. A southerly wind reversal has developed adjacent
to the coast as the strongest northerly winds move offshore early
Sunday morning. Southerly winds 5 to 10 knots will advect IFR
ceilings into CEC early Sunday morning. Both coastal terminals are
expected to see reduced visibilities with mist/fog through sunrise.
Model soundings show the marine layer reluctant to scatter out on
Sunday.


&&

.MARINE...The tight coastal pressure gradient will continue
to ease into Sunday. Gale gusts will retreat into extreme NW PZZ470
through Sunday, but steep and hazardous wind driven seas 9 to 14
feet will continue. Winds and seas will still remain elevated in the
southern outer waters with moderate to fresh breezes and waves 7 to
9 feet. Conditions will diminish in the inner waters on Sunday as
the strongest winds idle further offshore. Gales are expected to
ramp up again on Monday, expanding into the southern outer waters
and pushing closer to shore. Seas are expected to respond
accordingly with another round of 12 to 16 foot waves. There is
increasing confidence in high pressure beginning to break down by
Tuesday, diminishing hazardous conditions 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 Monday
morning. Offshore flow begins to weaken slightly Monday night and
Tuesday morning, and more significantly by Tuesday night.

Upper-level moisture arrives from the east this afternoon into early
next week. 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...
     Extreme Heat Warning until 11 PM PDT Monday for CAZ102-105-
     107-108.

     Heat Advisory until 11 PM PDT Monday for CAZ106.

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

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 5 AM PDT early this morning for
     PZZ450.

     Hazardous Seas Warning until 5 PM PDT this afternoon for
     PZZ470.

     Gale Warning from 11 PM this evening to 11 PM PDT Monday
     for PZZ470.

     Small Craft Advisory until 5 AM PDT Monday 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