978
FXUS66 KEKA 271109
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
409 AM PDT Mon May 27 2024

.SYNOPSIS...High temperatures will be warm and summer-like today
inland due to an upper level ridge that has remained over over the
Western US during our holiday weekend. After a trough and subsequent
cooler temperatures Tuesday, much warmer temperatures are expected
late week and are eventually expected to peak on Friday.


&&

.DISCUSSION....Night skies are clear over Trinity and Lake
counties as an upper level high pressure over our areas is keeping
upward motion from initiating. Coastal stratus has already
started its battle to fill in the low elevation coastal areas
tonight. Satellite imagery is already showing dense coverage over
most of the northern Humboldt coast while at Mendocino and
northern Del Norte counties, winds at about 2500ft are flowing
offshore. This offshore flow is currently prohibiting the
possibility of marine stratus reforming due to compressional
heating. HREF probabilities for cloud heights below 1000 ft are
around 55 percent for Humboldt Bay, 25 percent for the Del Norte
Coast, and 35 percent for the Mendocino coast. whatever stratus
that does form is expected to lift by the late morning and mostly
clear skies and pleasantly warm temperatures will then prevail
throughout this Memorial Day. Temperatures inland Monday will warm
steadily throughout the day as solar heating will have no
hindrance due to clouds, with high temperatures in the low to mid
80s in most of the interior valleys. Coastal temperatures will
range from the upper 50s and 60s with breezy onshore winds
building throughout the day.

A trough moving through this afternoon will allow for some moisture
and instability to move through. This combined with increased
temperatures will enhance instability, bringing the potential for
some light rain showers to pop up in the higher terrain of Trinity
and Mendocino counties. The chance for thunder is nonzero, but with
little mid-level moisture and low lapse rates, chances are low. NBM
gives around a 10 percent probability to see thunder, while SREF
gives around a 20 percent chance.

The an incoming trough arriving Tuesday morning will allow the
formation of more coastal stratus and even some drizzle. Widespread
high altitude cloud cover on Tuesday morning will lead to cooler
temperatures inland on Tuesday afternoon. A ridge will reform over
the area on Wednesday, gradually warming up the interior. Mid to
high 80s are forecast for Thursday, while high 80s to low 90s are
forecast for Friday. Afternoon wind gusts are possible as well, with
probabilities for wind gusts above 25 mph near 70 percent along the
coast Thursday and gust above 30 mph near 35 percent Friday. An even
stronger ridge will lead to warm temperatures peaking on Friday as
confidence builds among model ensemble members. Ensemble members are
even starting to show some agreement on a weaker ridge persisting at
least through Saturday. DS

.AVIATION....Some status has spread across Humbodlt county along the
coast and up the inland river valleys. So far this has brought MVFR
conditions, but these are gradually lowering and will likely drop
into IFR for a period of time this morning. This is also expanding
and may make it into Crescent City this morning bringing ceilings
around 1000 feet. These clouds are expected to erode by midday, but
return in the evening. An approaching trough may bring some drizzle
and lower visibilities along with IFR ceilings tonight. Short
periods of LIFR are possible but the probabilities of it being this
are lower. MKK

.MARINE...An upper level trough moving into the Pacific Northwest
will keep winds lighter today and Tuesday. Winds will be slightly
stronger south of Cape Mendocino and have extended the small craft
advisories out through Tuesday night. Waves are a combination of
wind driven seas and a small northwest swell around 9 seconds.
Tuesday a new swell builds in to around 6 feet at 12 seconds by the
afternoon.

Wednesday high pressure starts to strengthen again and this brings
near gale to gale force winds to the waters.  Confidence is growing
in these gales. The NBM is showing over an 85 percent probability of
gale force gusts on Thursday. Once these winds pick up the swell is
expected to be obscured by the wind driven waves. Winds are expected
to start to decrease Friday and into the weekend. MKK


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 AM PDT Wednesday for PZZ455-
     475.

&&

$$

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