815
FXUS66 KEKA 051311
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
553 AM PDT Wed Jun 5 2024

.SYNOPSIS...High pressure and hot interior temperatures will
continue to intensify today and will peak on Thursday. This pattern
will bring major heat risk to hot interior valleys, especially in
Lake County. Otherwise typical summer weather will continue through
the weekend.


&&

.DISCUSSION...Surface high pressure will continue to build today,
bringing hot interior temperatures. NBM shows a 15 to 30% chance of
highs over 100 this afternoon with a 50 to 70% chance of such highs
by Thursday afternoon. Heat risk will be greatest in southern
Mendocino and especially Lake County where the strong inversion of
the Sacramento Valley will help keep overnight lows as warm as 70.
Such prolonged heat will be sufficient to pose a major risk to at
risk groups. That said, all forecast highs are well below record
highs for this time of year which are closer to 110 for most
interior valleys.

Beyond temperature, strong solar heating will also help increase
surface instability. At the very least, this will most likely
generate more impressive and visible afternoon cumulus clouds over
high terrain. Model sounding suggest an impressive 600 to 1000 J/Kg
of CAPE of the Trinity Alps late Thursday afternoon. Despite this
fact, total column moisture is marginal at best and any lifting
would have to break through a midlevel cap and reach near 20 kft to
for thunderstorm formation. These factors make the formation of
isolated afternoon thunderstorms possible though unlikely (10 to 15%
chance) Thursday evening.

Closer to the coast, high pressure will continue to promote a thin
but persistent marine layer with temperatures solidly in the 60s and
stubborn coastal fog and stratus. Strong heating, however, will most
likely promote gusty north winds in the afternoon that will at
least temporarily help disrupt cloud cover.

High pressure will weaken into the weekend with a narrow trough
crossing the area around Sunday. Such a pattern will push marine
influence further inland and bring interior temperatures back into
the low to mid 80s. With little moisture to speak of, however,
essentially no ensemble members show rain with the trough beyond
coastal drizzle. Essentially all cluster ensemble members show a
ridge of high pressure centering over the Pacific Northwest early
next with low pressure stalled off the California Coast. Such a
pattern will bring typical to slightly above average summer
temperatures. Only about 15% of ensemble members currently show any
temperatures hotter than the current heat wave. /JHW


&&

.AVIATION...Stratus overnight has made its way up the Eel valley,
and may make it as far as Ft. Seward before sunrise. Stratus has
developed more density in the early morning hours, bringing flight
categories down to LIFR at KCEC and KACV with 1/4 to 1/2 mile
visibility and 200 foot ceilings. Soundings at the coastal terminals
show a subsidence inversion lasting into the early afternoon but
mixing and drying out soon after with VFR/MVFR until the evening.
Models are showing a southerly reversal which may bring stratus back
tonight and a return to LIFR conditions at KCEC and KACV by late
tonight. KUKI will have prevailing VFR conditions with a return of
gusty northerlies by the afternoon. /EYS


&&

.MARINE...Northerlies have already ramped up this morning with
gusts at Pt. St. George and Pt. Arena around 20 to 25 kts. The
southern waters will be the first to reach Gale in coverage by the
afternoon with the northern waters reaching near Gale in most areas
but focused expansion fans will be closest to Oregon waters near the
41.6N latitude. Gale gusts to 40 kt are probable again on Thu, but
once again the coverage appears to be localized and confined to
narrow corridors in the outer waters. Steep short period waves will
steadily build today, reaching 9 to 11 feet at 9 seconds. This is
borderline for a hazardous seas warming, but sufficient when
decaying NW swell is added. A late season NW swell of 10 to 12 feet
at 16 seconds will also arrive early today and then gradually decay
through Friday. The combination of the NW swell and locally
generated northerly waves will yield seas up 13 to 15 feet by late
this afternoon and into the evening. This typical strong northerly
wind regime with very steep northerly waves will persist into Thu
before backing off on Fri. Steep northerly waves and resurgence of
northerly winds is expected for the weekend, though exact magnitude
of winds and timing remain uncertain. /DB /EYS

&&

.BEACH HAZARDS...A large long period NW swell will build early
Wednesday with significant swell heights up to 11 feet at 16-17
seconds during the morning. This high energy swell has the potential
to bring a moderate risk of sneaker waves. Shorter period NW swell
of 7-9 feet at 7-9 seconds may mitigate the risk for the Mendocino
coast. However, the risk remains with an increase of beachgoers
looking for relief from the interior heat. A beach hazard statement
has been hoisted for the entire coast. /ZVS/DB


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Beach Hazards Statement through Thursday morning for CAZ101-
     103-104-109.

     Heat Advisory from 8 AM this morning to 8 PM PDT Thursday
     for CAZ114-115.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Hazardous Seas Warning until 3 PM PDT Thursday for PZZ450-
     470.

     Gale Warning from 8 AM this morning to 9 AM PDT Thursday
     for PZZ455-475.

&&

$$

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