037
FXUS66 KEKA 152041
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
141 PM PDT Tue Jul 15 2025

.SYNOPSIS...Inland temperatures continue trending down this week
while still remaining warm. The coastal stratus will become more
persistent over the coastal regions, lowering the daytime highs
for some.


&&

.DISCUSSION...Upper troughing to the north through the Pacific
Northwest is suppressing high pressure over our region today. Inland
temperatures are forecast to be 5-8 degrees cooler today than
yesterday as a result. The low-level inversion has strengthened
today, and will remain strong to moderately strong this week. Broad
coastal eddies and strengthening southerly return flow along the
coast will begin to develop this afternoon, and will strengthen
Wednesday. A weak shortwave trough will also develop off the coast
Wednesday. In response, the coastal stratus will become better
embedded and will hold daytime highs down a bit where clearing
does not occur.

There is a slight chance (10-15%) for dry thunderstorms in northern
Trinity County this afternoon. Model soundings show some elevated
instability, and some moisture remains available. Some cumulus
clouds are observed on visible satellite. Confidence is low as
there is still some CIN, but chances are not zero. The setup
remains similar Wednesday afternoon, but with slightly less
moisture available. CAMs are showing a better setup in Siskiyou
County, but these could drift westward into Del Norte. Chances
remain low, 5- 10%, but will need to be watched.

A similar pattern remains in place for much of the week with a
series of shortwaves moving into the Pacific Northeast. This will
keep temperatures moderated in the 90`s. By Thursday, NBM
probabilities of triple digits in Trinity and northeast Humboldt
fall off to less than 30% into the weekend. JB/JJW


&&

.AVIATION...(18Z TAFs) A deeper stratus layer will continue to
surge around the North Coast this morning as an eddy flows between
Southern Oregon and Cape Mendocino. Stratus is expected to clear out
from KACV and KCEC through the morning with only a 20% probability
of IFR conditions from 20Z-02Z. Slight clearing is already visible
on satellite imagery around Humboldt Bay as of 1715Z. As stratus
clears today, expect scattered to broken ceilings to persist before
a return to IFR conditions around sunset then back to LIFR
conditions around 04Z along the coast as a strong surface inversion
traps moisture close to the terminals. Inland, VFR conditions are
expected with potential for smokey visibilities as well as light
surface (<10kt) and elevated winds (<15kt) in Trinity, interior
Humboldt and NE Mendocino counties.


&&

.MARINE...Near- gale force winds are already beginning to ease this
morning, before continuing to subside midday through the evening. As
these winds die, these steep wind driven seas are expected to weaken
as well leading to calm conditions Wednesday. A stronger southerly
winds is expected directly offshore and north of Cape Mendocino
Wednesday. OVerall however, moderate breezes expected from Wednesday
through Friday. Fog and stratus is to be expected as well with
potential degraded visibilities through the next 48hrs, especially
at nighttime and in the early mornings.

&&

.FIRE WEATHER...Some remnant moisture, instability aloft, and
broad forcing will continue the chances for a couple
thunderstorms over northeast Trinity County this afternoon, with
some remaining chances into the evening. Minimum RH will inch
higher Wednesday while overnight recoveries remain good. A weak
shortwave trough will increase southerly to southwesterly winds
locally Wednesday afternoon in Lake and Southern Mendocino
counties. Inland temperatures will inch slighlty higher late this
week and through the weekend. Minimum RH will drop into the low
20s to mid teens with some increasing westerly winds through that
period. JJW


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 8 PM PDT this evening for PZZ450.

     Small Craft Advisory until 3 AM PDT Wednesday 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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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png