822
FXUS66 KEKA 120740
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1240 AM PDT Wed Aug 12 2026

.KEY MESSAGES...

* Warm, near-normal temperatures expected for the interior today.
  Cooler temperatures are likely late week into the weekend.

* Smokey conditions likely from the MP 18 Fire, focused in the
  Trinity River Valley.

* Slight chance of interior thunderstorms Thursday into Saturday.

* Minor coastal flooding is possible around Humboldt Bay at the
  evening high tide tonight.

&&

.SYNOPSIS...Interior temperatures trend below normal late in the
week. Coastal areas continue to have near normal temperatures
with overnight stratus clearing in the afternoons along with
breezy northwest winds. There is a slight chance for dry
thunderstorms in the interior late this week and into Saturday.

&&

.DISCUSSION...Smoke from the MP 18 fire continues to impact air
quality over Northern California, particularly in the interior
valleys of Humboldt and Trinity counties. Depending on fire
containment, expect a similar pattern to carry through the week.
The low level inversion is showing signs of weakening as more of
a troughing pattern develops, and this will help clear out the
smoke more efficiently over the coming afternoons.

The troughing will continue to lower interior daytime highs.
Temperatures will be near or below climatological normals today,
followed by continued lowering to below normals through the
extended forecast. The marine layer is deepening and extending
farther inland, and will be conducive to producing light drizzle
over the coming days.

The broad troughing and embedded disturbances will also bring low
chances for some showers or perhaps thunderstorm activity. A weak
surge of monsoon moisture associated with a shortwave disturbance
may clip portions of the southern zones Thursday, but even the most
aggressive modes keep the moisture SE of Lake County at this time.
This day will still be watched regarding any dry lightning potential
through Trinity County (5%), especially if the moisture flux nudges
northwest at all.

A secondary wave will move NE over Northern California Friday into
Saturday morning. This disturbance will carry higher instability and
moisture (though still meager), giving a slightly higher chance
for some thunderstorm activity (5-10% over Trinty County northward
through far eastern Del Norte County, and 10-15% over Siskiyou
County and far northeast Del Norte). There would be a potential
for nocturnal activity late Friday as well if storms occur at all.
precipitable water values will be on the higher side, and
precipitation reaching the ground would be possible. That said,
this is still a very low confidence forecast; however, it will
still be watched very closely due to historical poor model
handling of the setup type and the impact even a little lightning
would have regarding fire potential over the very dry vegetation.


&&

.AVIATION...(06Z TAFs)...Coastal stratus has returned bringing IFR
ceilings. CEC has only seem brief impacts late Tuesday evening,
but southerly winds will likely bring stratus for much of the
early morning. IFR ceilings are likely before sunrise with the
possibility for LIFR ceilings and visibilities around sunrise.
Ceilings will lift shortly after sunrise. While some improvement
is likely in the afternoon, there is around a 50% chance at ACV
and CEC for IFR to MVFR stratus impacts all day. This may also be
in the form of stratus right off the coast that will periodically
impact the terminals. Most interior areas are likely to remain VFR
outside the early morning in the Trinity River Valley where smoke
is expected to accumulate. /JB

&&

.MARINE...Strong northerlies with gale conditions continue in the
outer waters. These winds are generated steep and hazardous seas up
to 12 ft at 10 to 11 seconds. These larger seas will periodically
migrate into the inner waters following the afternoon/evening
stronger wind surges. Seas of up to 11 ft have occasionally been
observed at the North Spit buoy. Northerly winds will drop below
25 kts Thursday afternoon as troughing enters the region. The
northerlies will drop more substantially Friday and especially
through the weekend as troughing weakens the pressure gradient.


&&

.FIRE WEATHER...Elevated fire weather conditions continue within
the mountains of Del Norte and in the King Range as winds remain
gusty. In Del Norte, easterly winds gusts of up to 30 mph are
possible overnight tonight. Similarly in the King Range there
will be gusty afternoon northerly winds with poorer overnight
recoveries in the higher elevations.

Minimum RH and overnight recoveries will continue to improve with
moistening westerly flow and lower daytime highs from the
breakdown of the ridge of high pressure. A troughing pattern then
takes shape, which will maintain good recoveries and also
increases chances for a deepened marine layer to infiltrate
farther into the interior.

A weak surge of monsoon moisture associated with a shortwave
disturbance may clip portions of the southern zones Thursday, but
even the most aggressive modes keep the moisture SE of Lake County at
this time. This day will still be watched regarding any dry
lightning potential through Trinity County (5%), especially if the
moisture flux nudges northwest at all.

A secondary wave will move NE over Northern California Friday into
Saturday morning. This disturbance will carry higher instability
and moisture (though still meager), giving a slightly higher
chance for some thunderstorm activity (5-10% over Trinty County
northward through far eastern Del Norte County, and 15% over
Siskiyou County and far northeast Del Norte). There would be a
potential for nocturnal activity late Friday as well if storms
occur at all. Storm movement would be to the north/northeast at
just over 20mph.


&&

.COASTAL FLOODING...Measured sea levels continue to run approximately
0.7 to 0.8 ft above the predicted tide level in Humboldt Bay. The
predicted tide at the North Spit tide gauge is 7.84 ft MLLW at
12:10 am tonight. The anomaly would need to increase to nearly a
foot. This is possible as northerly winds will be diminishing and
may locally become southerly which would push more water into
Humboldt Bay. That said, any flooding will be very minor if it
occurs.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Coastal Flood Advisory from 10 PM this evening to 1 AM PDT
     Wednesday for CAZ103.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Coastal Flood Advisory from 10 PM this evening to 1 AM PDT
     Wednesday for PZZ415.

     Small Craft Advisory until 9 AM PDT Thursday for PZZ450-455.

     Gale Warning until 9 AM PDT Thursday for PZZ470-475.

&&

$$

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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