275
FXUS66 KEKA 122149
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
249 PM PDT Wed Jun 12 2024

.SYNOPSIS...Cooler temperatures will be the trend starting Thursday
with more substantial cooling over the weekend. Northwesterly winds
strengthen in the interior with strong gusts Thursday night
into Friday morning.


&&

.DISCUSSION...Dry weather continues with temperatures in the
interior reaching the High 80s to low 90s, with a few areas reaching
closer to the upper 90s and low 100s. Trinity county temperatures
look to be their highest near Big Bar and Weaverville, around 96.
Mendocino interior has a few higher temperatures at Potter Valley
and Ukiah at 99 and 100 respectively. Lake county will approach a
moderate Heat Risk in the southern and eastern areas bordering
Colusa, Yolo, and Napa. No Heat Risk advisory has been implemented
at this time due to less area coverage and temperatures at
marginal threshold. However, ground observations at Daly Place,
Middletown, and Hidden Valley Lake have reached or exceeded 100.
Tomorrow`s forecast will lower the probability of heat risk as
cooler trends prevail.

NBM remains consistent with temperatures diminishing on Friday as
upper level ridging shifts south and a trough develops over the
Pacific NW. Stronger westerly to northwesterly winds are expected to
develop on Friday across the interior especially interior Mendocino
and Lake counties. More substantial cooling along with stronger west
to northwest winds are expected in the interior this weekend as
another 500mb trough dips down from the NW. Strongest winds will
most likely occur on Sunday with the passage of a shortwave trough.
With fine grassy fuels cured, the strong westerly to northwesterly
winds may pose a slight risk for rapid spreading grass fires. The
highest risk appears to be in Lake and perhaps eastern Trinity and
southern Mendocino.

This trough is forecast to be relatively dry and right now the
potential for any precipitation is quite meager, 5-10% chance for
mostly Del Norte late in the weekend. The cooler/drier air will also
result in chilly overnight temperatures once winds decouple.
There is a chance (20-40%) for brief morning frost in the colder
valleys of Trinity and eastern Humboldt counties on Sunday. The
frost threat will persist into Monday morning with about the same
probability of occurrence.

Also, rain possibilities increase early to mid next week (June 17-
19), though still quite meager with NBM probabilities for 0.10in or
more in 24 hours no more than 22% for mostly Del Norte and northern
Humboldt counties. NBM has temperatures trending upward by mid week,
however the trough may linger into mid next week and strong warming
appears unlikely at this point. /DB /EYS

&&

.AVIATION...Marine stratus redeveloped along the coast from Cape Mendocino to
Del Norte. A couple of pireps reported bases around 600 feet
average and tops around 2,000 feet at ACV, but halve that height at
CEC. Stratus was slightly more extensive today and more stubborn to
mix out. Winds were "unhurried" to ramp up today, but finally
started to increase by mid-afternoon (at least at CEC). Winds
should stick around up to a couple of hours after sunset. Low clouds
will return to the coast overnight...starting first around Humboldt
Bay, then advecting toward CEC. UKI will continue to stay VFR with
typical afternoon breezes. /TA

&&

.MARINE...Gale conditions are in full swing across the outer
waters this afternoon with nearshore wave heights reaching 10-12
feet. Wave periods building to 10-11 seconds as a SW long period
swell fills into the waters. Peak seas and winds expected to
develop late this evening and overnight, with significant wave
heights approaching 15 feet alongside gusts up to 45 knots. Hi-res
models are highlighting potential for an area of localized gusts
reaching 50 knots in the corridor of an expansion fan downwind of
southern Oregon.

Steep and hazardous seas expected to continue through late Thursday -
gusty winds will slowly diminish and decrease in zone coverage as
the thermal trough and associated pressure gradient slackens. Fairly
marginal gales expected to persist through Friday in the southern
waters within an expansion fan downwind of Cape Mendocino.
Otherwise, seas will begin to dip below 10 feet for the start to
this weekend.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Hazardous Seas Warning until 9 AM PDT Thursday for PZZ450.

     Gale Warning until 9 PM PDT this evening for PZZ455.

     Gale Warning until 9 AM PDT Thursday for PZZ470.

     Gale Warning until 3 AM PDT Friday for PZZ475.

&&

$$

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see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png