748
FXUS66 KEKA 110851
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
151 AM PDT Mon Aug 11 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 week.


&&

.KEY MESSAGES...

* Very hot weather with temperatures in the triple digits
  continues today across the interior valleys.

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

* A gradual cool down is expected beginning on Tuesday and
  continuing through late week.


&&

.DISCUSSION...Latest Satellite imagery shows stratus and patchy
fog blanketed much of the coastal waters and adjacent land areas
overnight, while mostly clear sky across the interior. Although,
a southerly reversal winds is helping the stratus to advect up the
Russian River valley into southern Mendocino County. Low clouds
are expected to erode back to the coast with the daytime heating,
although stratus are expected to be more stubborn to scatter out
along the immediate coast this afternoon.

Dry weather and above normal temperatures will continue today
with the highest heat shifting eastward. As results, temperatures
will down a few degrees along the coastal counties, but still
conditions remain hot in the interior. Areas of northern Trinity
and northeast Humboldt are still forecast to see high temperatures
between 100 and 110F. The Heat Advisory remains in effect through
11PM this evening for northeast Humboldt and Northern Trinity as
these temperatures still do present a moderate to major risk for
heat- related illness. Onshore flow will keep coastal
temperatures moderated, largely in the 60`s.

Tuesday, the ridge break down and a shortwave will gradually squeeze
down the coast bringing an end to the worst of the heat and
increasing onshore flow. However, temperatures are expected to
remain in the upper 90`s to 105, with the highest temperatures in
Trinity County.

Ensemble clusters and deterministic model guidance are showing 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. While unlikely, some ensemble
members are showing a trough digging farther south into northern
California this weekend, and the wettest members do show some
potential for rain for the northern forecast area. /ZVS


&&

.AVIATION...A southerly surge of coastal stratus has brought LIFR
conditions to the entire coast of northern California tonight.
Expect light winds from variable directions, yet mostly from the
south, due to the southerly surges and eddies forming along coastal
terminals. Visibilities remain variable as well with ASOS measuring
dense fog of 1/2SM to P6SM conditions under the cloud deck. Come
late morning TAF LAMP probabilities show only a 20% chance of
conditions improving above IFR status along the coast due to cloud
ceilings. Inland, VFR is expected with calm winds tonight. Height
density issues continue to be possible as inland temperatures rise
to over triple digits Monday and Tuesday.


&&

.MARINE...Northerly continue to move further offshore tonight as a
southerly wind surge fills into the coast, accompanied with areas
of dense fog leading to visibilities <1/2NM. Other than the
slighter milder northerly wind waves, two long period swells will
fill in today, one from the south-southwest (3ft@17S) and another
from the northwest (3ft@17s). These swells have the potential to
create square wave pattern due to the perpendicular wave directions
creating possible grid-like patterns. Conditions remain mild early
this coming week with breezy northerlies likely to return by
Wednesday/Thursday.


&&

.FIRE WEATHER...Nosignificant changes to the previous forecast.
Surface observation reports poor overnight recoveries continues
with values generally in the mid 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. Breezy offshore winds
have generally eased in the higher terrain, but conditions remain
hot and dry. RH recoveries remain poor on the ridges (20- 40%).
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 to 11 PM PDT Monday for CAZ105.

     Heat Advisory until 11 PM PDT Monday for CAZ107.

NORTHWEST CALIFORNIA COASTAL WATERS...
None.
&&

$$

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