299
FXUS66 KEKA 031153
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
453 AM PDT Mon Jun 3 2024

.SYNOPSIS...Post-frontal showers tapper off this morning. Hot,
dry weather will rapidly build back in mid week with high heat
risk for many interior valleys, especially Lake County, Wednesday
and Thursday. Breezy north- northwesterly winds return Wednesday
and Thursday, with gusty winds over the coastal headland and
exposed ridges. There is a potential for late afternoon and
evening thunderstorms on Thursday in northern Trinity.


&&

.DISCUSSION...A cold front is moving onshore across northwest
California early Monday morning. As of 2AM PDT, a period of heavy
rainfall was occurring along the coastal ranges in Del Norte
County and northern Humboldt with rainfall peaking into 0.25" to
around 0.35"/hour range. As the front continue moving east, rain
has spread across Humboldt County and is spreading into portions
of Trinity and northern Mendocino. The cold front will continue
to eject eastward away from the west coast, with post- frontal
showers gradually tapper off during the morning hours.
Temperatures will be cooler across the interior with highs in the
70`s.

High pressure over eastern Pacific will build quickly over the
West Coast in the wake of the this front. The mid level heights
will rise slightly, and a warmer airmass will gradually develop
across the WRN CONUS during the remainder of the week. Interior
highs temperatures are forecast to peak on Wednesday and Thursday,
with values across the hottest valleys ranging from 95-105
degrees. The heat risk is forecast to be minor to moderate over
the area, but a major heat risk is expected to occur over portions
of Lake County. Thus, this will affect anyone without effective
cooling and/or adequate hydration. As a result, a Heat Advisory is
in effect for Lake County from Wednesday morning through Thursday
night. An advisory product is not ruled out for Trinity and the
interior portion of Mendocino. Elsewhere, slightly cooler
temperatures in the 90s are expected within interior Del Norte and
interior Humboldt. Temperatures along the coast are expected to
warm up as well, but nothing significant with highs just few
degrees above normal.

Additionally, a thermal trough is expected to develop near the
coast Wednesday. This will promote breezy north- northwesterly
winds each afternoon Wednesday and Thursday over the exposed
ridges and coastal headlands, with gusts from 25 to 35 mph at
times...locally higher gusts possible over the King Range. NBM
probabilities shows a 60% to 80% fro gusts of 40 MPH or more in
the KIng Range, and 45% chances for Crescent City.

Some moist inflow from the south will bring the potential for
late afternoon and evening thunderstorms on Thursday, or even
overnight thunderstorms. GFS and NAM model sounding guidances are
suggesting elevated instability and steep lapse rates over Trinity
County. At this point, include a slight chance of thunderstorm
over the Trinity Horn Thursday evening, where thunderstorms
development looks possible.

Friday and into the weekend, the ridge starts to shift eastward
and the flow becomes more zonal. This is expected to start to
deepen the marine layer and bring some cooler air to the coastal
counties, mostly north Cape Mendocino. Trinity, eastern Mendocino
and Lake counties are not expected to see much change on Friday.
Temperatures will continue to slightly cool down during the
weekend.



&&

.AVIATION...With the passing of an atmospheric river, rain rates
have increased in the northern sectors of the CWA. This includes
KCEC which experienced heavy rain overnight reducing visibility to 4
miles or less. Gusty southerly winds have begun to ease at KCEC as
of 11z and rain rates are expected to decrease by day break. LIFR
conditions currently at KCEC will improve to MVFR by the afternoon
as ceilings lift and visibility improves. Winds have been out of the
southwest at KACV with LIFR conditions expected to improve to MVFR
by the afternoon as well. Light rain and low visibility at KACV will
improve to MVFR by the afternoon as well. KUKI will begin to get
light precipitation by the late morning as the moisture plume shifts
south. Gusty north winds return to KUKI by the early afternoon with
MVFR to VFR conditions prevailing. /EYS


&&

.MARINE...Summary: A series of small mid period swells through
Tuesday will be followed by a seasonably large and long period WNW
swell on Wednesday. Northerly winds increase Tuesday in the southern
zones, and will strengthen and expand north Wednesday. The short
period N seas and long period WNW swell will create a chaotic seas
state Wednesday.


Today, a slightly larger, mid period NW swell will move in, building
to 6-8 ft at 11 seconds early Tuesday morning. Light, split wind
flow will transition to strengthening northerlies in the southern
zones Monday night.

Tuesday, the NW swell will hold in size, then a slightly larger
reinforcing mid period swell then pulses in Tuesday afternoon with
seas 6 to 8 ft. Northerly winds in the southern waters will further
increase, reaching 22 kts south of the cape in the afternoon.

A strong gale on the southern periphery of a late season Aleutian
low pressure area, driving eastward, will deliver a long period
swell on Wednesday. A resulting seasonably large, long period WNW
swell (300 degrees) will build in early Wednesday morning, currently
forecast 10 to 12 ft at 15 seconds. Northerly winds will be on the
increase throughout the day, with gale conditions probable in
portions of the waters by late Wednesday. There looks to be some
shelter from the strongest winds in the northern inner zones. The
combination of steep, short period northerly seas and the long
period swell will generate a confused sea state up to 15 ft

On Thursday, the long period swell will begin slowly easing in size.
The northerlies will offer more potential Gale gusts in portions of
the waters in the wind favorable locations south of the capes, with
some shelter in the inner zones. /JJW /EYS


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Heat Advisory from 8 AM Wednesday to 8 PM PDT Thursday for
     CAZ114-115.

NORTHWEST CALIFORNIA COASTAL WATERS...
None.
&&

$$

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