123
FXUS66 KEKA 102153
AFDEKA
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
253 PM PDT Thu Jul 10 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 work their way
north on Saturday and Sunday. Northeast winds overnight on
Thursday and Friday will help to limit the stratus and potentially
bring warmer temperatures to the coast.
&&
.DISCUSSION...High pressure continues to build over the area and
hot temperatures are starting to take hold in Mendocino county. A
thin strip of stratus remains in place as of 2pm along portions of
the coast. If this clears out it may take considerable time to
come back tonight. 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. This may also
bring some stratus to the immediate Mendocino coast. So the
heat advisory ends for the Ukiah and Willits 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, but did add that to the forecast. One potential challenge
in this forecast is the presence of smoke may keep temperatures
cooler than expected. General went with the idea that the smoke
would not be sufficient to keep temperatures cooler over a large
area.
Monday the ridge continues to shift east and the marine layer may
start making its way north and starting to cool 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 there. Tuesday
hot weather continues, but it is expected to be more confined to
areas well away from the coast in Trinity county. Wednesday an
upper level trough approaching the area continues the slow cooling
trend, but most areas are expected to still be in the 90s. MKK
&&
.AVIATION...Stratus along the Del Norte and Humboldt coasts has
started to lift and scatter early this afternoon. Breezy northerly
winds are likely this afternoon and evening, with strong winds at
CEC possibly exceeding 25 kts. Mostly clear skies will follow for
across the area into the evening, apart from wildfire smoke. Stratus
is likely to return this evening and overnight to the Humboldt
coast, with a shallow marine layer bringing LIFR/IFR ceilings and
visibilities. Northerly winds will likely ease overnight for most of
the area, aside from CEC. Southerly winds are possible along the
immediate coast between ACV and CEC, which would advect stratus
northward. If northerlies remain strong overnight at CEC, stratus
will likely hit a barrier before affecting 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. JB
&&
.MARINE...Northerly winds have started to ramp up as a tight
pressure gradient sets up along the coast. Gale force gusts are
likely in the outer waters starting this afternoon into Friday.
Nearshore waters could see gusts of 20-25 kts in the afternoons, but
are largely insulated from the strongest winds. Steep, elevated seas
in the outer waters are likely to in nearshore 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. This is keeping just a very thin strip of stratus along the
coast this afternoon and even this may erode later this afternoon.
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. This inversion is expected to lower over the next couple
days as high pressure strengthens. The NBM is likely too high on
the rh due to the pattern shift from a deep marine layer. So it
has been lowered it by blending it with the FV3 model. This may
not be low enough, but it appears to push it in the right
direction. 850 and 925 mb winds are around 10 to 20 mph
overnight with rh recoveries only around 40 to 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 across the area will mainly be pushed south from the Butler
Fire. This will trend 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 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. MKK
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
Extreme Heat Watch from Saturday morning through Sunday
evening for CAZ102-105-106.
Heat Advisory from 11 AM Friday to 11 PM PDT Sunday for
CAZ107-108-111-114-115.
Heat Advisory from 11 AM Friday to 11 PM PDT Saturday for
CAZ110-113.
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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https://www.weather.gov/images/eka/zonemap.png
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