287
FXUS66 KEKA 052214
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
314 PM PDT Fri Jul 5 2024

.SYNOPSIS...Extreme heat will peak on Saturday as high pressure
centers directly over NorCal. Enhanced fire weather risk continues
with westerly diurnal winds, especially in trinity and Lake
counties. Temperatures will ease slightly but remain above average
through early next week.


&&

.DISCUSSION...Daytime interior highs climbing into the 100`s again
today, likely topping out a few degrees higher than yesterday. Areas
already experiencing Excessive Heat Warnings - including valleys of
interior Mendocino, Trinity, and Lake counties - are exhibiting
high probabilities of highs exceeding 105 this afternoon.
Additional temperature records likely to be broken, especially
after being compounded with several days of heat. Gusty diurnally
driven winds enhanced by strong surface heating/low level
instability will increase risk of fire weather in portions of
southeastern Lake County through Saturday.

With the high pressure ridge moving directly overhead, temperatures
will surge even higher on Saturday to meet Major and Extreme
HeatRisk criteria in many interior portions of the CWA.
Aforementioned interior valleys still showing a 60% chance of
exceeding 108-110 degrees by 3 PM. With offshore flow overnight,
unusually high temperatures will surge toward the southern
Humboldt/Mendocino coast to bring highs into the mid 80`s, 70`s
further north. Lower probabilities for coastal highs reaching into
the 80`s.

As afternoon temps heat up, westerly flow is anticipated to increase
across Trinity, Lake and eastern Del Norte counties. With gusts up
to 20-25 mph possible, the Red Flag Warning will continue in SE Lake
while a Fire Weather Watch begins for Trinity Saturday afternoon.
Critically low RH`s in the single digits and teens will exacerbate
these conditions.

Despite the heat, a mild surge of marine moisture will begin to
slowly make its way inland as the westerly flow increases late this
weekend. The marine layer will still be fairly week, but overnight
RH recoveries are expected to improve to exceed 50% for Humboldt,
Del Norte and Mendocino counties.



&&

.AVIATION...ACV/CEC...The coastal terminals are in solid VFR conditions this
afternoon. Under the dry airmass and strong subsidence, the stratus
has greatly struggled to become better organized off the Mendocino
coast. High resolution Models have been overdoing the stratus over
the past couple of nights, but there is a higher probability of
shallow stratus tonight. MOS guidance is more aligned with at least
a brief period of shallow, ground fog formation for early Saturday
morning, and the synoptic setup favors that solution if stratus does
not fill in. IFR to LIFR conditions would develop with these
scenarios, but confidence is low to moderate (57%). Haze and a thin
smoke layer from the Shelly Fires in Siskiyou County became trapped
under the low level inversion last night, and that should redevelop
tonight with minor VIS reduction.

UKI....Firmly in VFR criteria. The occasional gusts this afternoon
will subside and transition to calm winds. VFR is expected through
this 18Z TAF period.


&&

.MARINE...Fair seas and calm winds prevail for all area waters
for the next 36 hours or so. Northwesterly winds start to build
Saturday night with seas responding by Sunday morning in the
northern outer waters as wind waves with square profiles develop.
Small craft advisory conditions will begin in the northern outer
waters Sunday morning with the previously mentioned square wind
waves which will expand into the southern outer waters by Sunday
afternoon. Aside from the standout spots around Cape Mendocino and
Point St George, the northerly winds of around 20 kts will be
confined to the outer water through the weekend, with lighter
nearshore winds.
/EYS


&&

.FIRE WEATHER...Hot temperatures continue and are expected to
bring RH down to 5 to 15 percent this afternoon. The typical
diurnal afternoon winds will be slightly enhanced by the hot
temperatures and this will increase fire weather conditions.
Tonight the valleys are expected to decouple again and see
recoveries of 40 to 50 percent. The thermal belts are expected to
see temperatures only drop to around 80 with RH recoveries around
20 to 30 percent. This will increase fire danger slightly.

Saturday afternoon northwest winds will increase again,
especially in southern Lake county. The red flag warning looks on
track in southern Lake county. Farther north in Trinity County
low RHs and breezy afternoon winds will enhance fire weather
conditions - a Fire Weather Watch will go into effect in the
afternoon. Sunday as the upper level ridge starts to push east
areas closer to the coast are expected to start seeing a slight
marine push. Winds are expected to weaken in Lake county, but may
remain elevated in Trinity county.

Monday there is still the potential for some showers and
thunderstorms in the afternoon. This will need to be watched as it
gets closer. For now the chance looks less than ten percent. /MKK


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Heat Advisory until 8 PM PDT Monday for CAZ102-112.

     Heat Advisory until 11 PM PDT Saturday for CAZ104.

     Excessive Heat Warning until 7 PM PDT Monday for CAZ105-107-
     108.

     Fire Weather Watch from Saturday afternoon through Sunday
     evening for CAZ283.

     Excessive Heat Warning until 8 PM PDT Saturday for CAZ106.

     Excessive Heat Warning until 8 PM PDT Monday for CAZ110-111-
     113>115.

     Red Flag Warning until 11 PM PDT Saturday for CAZ264.

NORTHWEST CALIFORNIA COASTAL WATERS...
None.
&&

$$

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