638
FXUS66 KEKA 211057
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
357 AM PDT Sat Sep 21 2024

.SYNOPSIS...Warm and dry conditions will continue to gradually
settle in today with continued gusty north winds along the coast.
Heat will peak early next week with above average temperatures
pushing out even along the coast.


&&

.DISCUSSION...High pressure is continuing to build across the
eastern Pacific and gradually drift towards shore. Gentle offshore
flow overnight coupled with very dry air aloft has allowed for clear
skies all around the area. Enhanced nighttime inversion are apparent
throughout interior valleys with high elevation lows in the mid 60s
compared to valley lows in the upper 40s.

The gradually building heat dome will allow temperatures to creep
upwards today with hot interior valleys reaching the mid 90s, which
is a solid 10 degrees above normal for most locations. Lingering
offshore flow this morning may aid in some brief warming near 70
along the coast, especially with clear skies, but gusty north wind
right along shore of 10 to 20 mph will generally pull marine
influence inland in the afternoon while simultaneously scouring out
any marine stratus.

High pressure will build and peak early this week with the hottest
temperatures most likely Monday and Tuesday. There is a 60 to 80%
chance of highs above 100 along the Russian and Trinity River
Valleys. In addition, most models are placing a close low off the
Central California Coast during this time. This low will encourage
offshore wind which which, combined with the high pressure, will help
push particularly warm conditions very close to the coast. Thank to
this pattern NBM has a 50 to 70% chance of highs over 100 in
Garberville and a 30 to 50% chance of highs in the mid 70s around
Humboldt Bay. Such above normal temperatures, combined with little
overnight relief will help support moderate and very localized major
heat risk. None the expected temperature, however, are near record
breaking.

There is high model agreement that high pressure will weaken by mid
next week and give way to a broad and shallow trough across the
Pacific Northwest. About 30% of model ensemble member shave the
trough dip just south enough to bring light wetting rain right
along the North Coast. Essentially no model members show any rain
more than a few tenth of an inch. Most model ensemble member show no
precipitation beyond coastal drizzle with trough just bringing
generally cool temperatures and increased clouds cover, especially
with a marine layer along the coast.

There is high confidence in a generally benign, dry, and seasonable
patten continuing through the end of the week. By next weekend there
is wide model disagreement. About 10% of cluster ensembles show a
widespread wetting rain event while 20% show the total opposite with
a moderate heat wave. The majority (70%) show weak high pressure and
generally dry but seasonable conditions. /JHW


&&

.AVIATION...Skies are clear over much of the north coast tonight due
to easterly wind aloft. Stratus development has yet to initiate this
morning and should remain as such throughout the day leading to VFR
conditions. Possible visibility reductions due to haze aloft over
the coastal terminals. Wind shear is forecast to be a threat at the
KCEC due to strong northerlies at the surface and easterlies aloft
at 2000 ft AGL. Tonight, there are low probabilities (~20%) of fog
returning to the coastal terminals according to the NBM and HREF
models. Inland, KUKI is forecast to remain as VFR conditions with
its daily wind patterns.


&&

.MARINE...Gale strength northerlies with gusts up to 40 kts have
developed over the waters. These winds have the highest coverage
over the outer waters, but gale conditions will intrude the inners
around Cape Mendocino and Point St George. In response to the winds,
seas will continue to build to 14 ft at 10 seconds by this evening.
These very steep and hazardous seas will propagate into the inner
zones until midday Saturday. Winds and seas will be very slow to
subside on Saturday.


&&

.FIRE WEATHER...Building high pressure has allowed for enhanced
thermal belts to form overnight. While protected valleys have
continued to see very high RH recovery above 80 percent, midslope
and high elevation locations are generally between 30 and 50 percent
early this morning. North wind offshore has also enhanced nighttime
northeast flow, with isolated gusts of 20 to 30 mph this morning
mostly just at the high elevations of the western Klamath Mountains.

Building heat and high pressure this weak will continue to enhance
fire weather conditions with daytime highs in the mid 90s to low
100s and minimum RH in the teens. Overnight recoveries will continue
to worsen at mid and high elevations with recoveries of 20 to 40
percent though Tuesday morning. Daytime winds will continue to be
mostly gentle and terrain driven, but low pressure of the central
california coast combined with high pressure will help enhance night
time northeast flow at high elevations. Northeast wind gusting up to
25 mph should be expected a high elevations late each night early
this week. This risk will be focused in the usual areas of Del Norte
and Lake Counties but will also include the usually calmer ridges
of Southern Humboldt and northern Mendocino Counties. Generally more
mild conditions will build in late in the week with increasing
marine influence. /JHW


&&

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

     Small Craft Advisory until 9 AM PDT this morning for PZZ455.

     Gale Warning until 11 PM PDT this evening for PZZ470.

     Gale Warning until 9 AM PDT this morning for PZZ475.

     Hazardous Seas Watch from 9 AM PDT this morning through
     late tonight for PZZ475.

&&

$$

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