385
FXUS66 KEKA 100850
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
150 AM PDT Sun Aug 10 2025

.SYNOPSIS...Hot and drier weather conditions expected through
Tuesday. Moderate to localized Major HeatRisk through Monday.
A gradual cool down is expected by mid to late next week.


&&

.KEY MESSAGES...

* Moderate to localized Major HeatRisk through Monday across the
  interior.
* Hotter temperatures across the interior valleys will result in
  major risk of heat-related illness for anyone without effective
  cooling and/or adequate hydrate.


&&

.DISCUSSION...Pics from sky depicts high clouds streaming across
the forecast area, while coastal stratus gradually blanket the
West Coast overnight. With a weak low-level inversion, diurnal
heating will allowed low clouds to burned off for much of the
immediate coast this afternoon.

Temperatures will peak today across most of the inland areas as
the high pressure strengthens aloft. Moderate to localized Major
HeatRisk continue through Monday across the interior valleys with
temperatures ranging from 100F to 115F, with the hottest
temperatures in northern Trinity and northeast Humboldt interior.
The Heat Advisory remains in effect for Today for Del Norte,
northern Humboldt interior, northern Trinity and southeastern
Mendocino interior. For these areas, there is a major risk of
heat- related illness for anyone without effective cooling and/or
adequate hydration. The Heat Advisory remains in effect through
Monday night for northern Trinity with the heat shifting eastward.
Coastal areas are forecast to be slightly lower than Saturday`s
reading as the onshore breezes should keep temperatures in the
mid to upper 60s.

Tuesday, the ridge break down and a shortwave will gradually squeeze
down the coast bringing a return to cooler weather and onshore
flow. However, temperatures are expected to remain in the upper
90`s to 105 across the hottest valleys, especially in Trinity
County.

Ensemble clusters and deterministic model guidance shows an upper
level trough from the northeast Pacific driving southward along
the coast on Wednesday and settling over the area late next week.
This will bring an enhanced onshore winds and a deepening marine
layer with coastal stratus. /ZVS


&&

.AVIATION...6Z TAFs...Stratus has started to form off the Humboldt
and Del Norte coasts and remains along the Mendocino coast. Models
are showing stratus moving northward around Cape Mendocino toward
ACV and CEC in the early morning hours. IFR to LIFR conditions are
possible if stratus does reach the terminals. While stratus is
likely to scatter out in the afternoon, models are in decent
agreement of stratus lingering nearshore for most the day. Some
occasional IFR impacts to the terminals in the afternoon are not out
of the question. Regardless, stratus is likely to return again in
the evening. Inland, VFR conditions are expected with mostly clear
skies. Breezy west winds are possible around UKI in the afternoon.
JB


&&

.MARINE...Strong northerlies continue to move off the coast early
this morning, with gales finally subsiding by sunrise. Gentle to
moderate southerly wind will replace the northerlies, with the
strongest winds nearshore and around Cape Mendocino. Fog is likely
to return with these southerlies. Seas will continue to subside as
winds ease. Other than diminishing wind waves, two minor mid period
swells will fill in today, one from the southwest and another from
the northwest. Conditions remain mild early next week, but northerlies
are likely to return by the middle of next week. JB

&&

.FIRE WEATHER...Breezy offshore winds continues over the higher
terrain areas of Del Norte County through this morning, while
generally light to gentle offshore flow elsewhere. Surface
observation depicts a slight improve in RH`s overnight recoveries
with the 24 hour RH change showing an increasing moisture values
up to 20 percent in the vicinity of the coastal areas. However,
poor RH`s recoveries continues with values generally in the 20`s
to 40`s percent on the ridges.


Hot and drier weather conditions are expected through Tuesday.
Very dry daytime RH`s values in the single digits and teens
percent will continue through Monday. Winds are expected to be
light during the day, yet westerly up valley winds may become
breezy each afternoon and evening. Dry weather will continue next
week, but with a gradual cooling trend and improved RH recoveries
by mid to late next week. On Thursday, elevated fire weather
threat should be possible with enhanced onshore winds and low
daytime RH in the teens and 20`s, especially in Lake County. /ZVS



&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Heat Advisory from 9 AM Sunday to 1 AM PDT Monday for
     CAZ102-105-113.

     Heat Advisory from 9 AM Sunday to 11 PM PDT Monday for
     CAZ107.

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

     Hazardous Seas Warning until 11 AM PDT Sunday for PZZ470.

     Small Craft Advisory until 3 PM PDT Sunday 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