Clearlake, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

285
FXUS66 KEKA 301255
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
455 AM PST Mon Dec 30 2024

.SYNOPSIS...
Dry conditions with cold overnight temperatures are expected today
into Tuesday. Temperatures will warm Tuesday night into Wednesday
as rain chances return and persist through Friday.

&&

.DISCUSSION...
The last few showers from the departing storm system over the
weekend are now dissipating over Del Norte County and the coastal
waters. A few sprinkles may also reach the Humboldt coast early this
morning but otherwise dry conditions are expected for the entire
forecast area by mid morning. With plenty of moisture around after
the recent rains, widespread interior valley fog has formed
overnight with some fog being quite dense. This fog should gradually
dissipate through the morning, possibly lingering into the afternoon
for some areas.

A very cold airmass has settled over the region behind the departing
system and low temperatures Tuesday morning are expected to bottom
out into the mid 20s for many interior valley locations and lower to
mid 30s along the coast. For southern Mendocino and Lake counties
there is the potential for some locations to drop to 30 degrees or
colder which meets the criteria for a cold weather advisory in those
areas. The criteria for a cold weather advisory is 20 degrees
farther north into northern interior Mendocino County, Trinity
County, interior Del Norte, and interior Humboldt counties. Thus, no
advisories will be issued for those areas despite colder low
temperatures.

This cold airmass will quickly be pushed east Tuesday into Wednesday
as warm onshore westerly flow re-establishes itself over the region.
A front will settle south into the northern half of the forecast
area as early as late Tuesday bringing rain showers to Humboldt and
Del Norte counties. There are minor differences in model outcomes,
including how far south rain reaches Tuesday night into Wednesday
night, but generally chances for rain are now looking more likely
for areas from northwest Mendocino County north into Del Norte
County into Thursday. Rain will come in spurts of shower activity
and may be heavy enough to keep flows elevated on some rivers. This
will be notable primarily because guidance has trended toward a more
potent system moving through the area Thursday night into Friday. If
the rain persists Wednesday through Thursday in Del Norte and
Humboldt counties and then the potential for heavy rain materializes
Thursday night into Friday, it wouldn`t be a shock to see more
flooding concerns in the northern half of the forecast area where
guidance is currently targeting several inches of total rain in this
period. The Weather Prediction Center is now centering the heaviest
rain near the Oregon/California border region with up to 7 inches of
additional rain in the mountainous terrain in that area before all
is said and done on Friday. This is a major change from what had
looked like a fairly tranquil time period only a few days ago.
Residents of Del Norte and Humboldt counties, in particular, should
stay tuned to see how the forecast trends over the next few days
considering how saturated the environment is at this point. It
wouldn`t take much to cause flooding of small streams and creeks
along with elevated flows on main stem rivers.

Areas farther south will likely see significantly less rainfall and
less of a concern for flooding with these systems. Still, the
forecast has definitely trended wetter and residents conducting work
sensitive to precipitation should keep a closer eye on the forecast
than they might have thought a few days ago. /RPA

&&

.AVIATION...
Biggest problem is fog potential, especially at the KUKI
terminal. Observations at the beginning of the TAF forecast reveal
1/4SM to 3/4SM visibility. Chances are low in the NBM for this
scenario (4-14% for less than a mile), but drop to 0% by 16Z, so a
TEMPO for LIFR visibility/VV001 seems prudent through 16Z. In the
post-cold front regime, the gustiest wind looks like KUKI as well,
and even there the median NBM solution peaks at 12 KTS from the
northwest. A general decrease in sky cover is expected as well. KUKI
visibilities may be a problem again tonight as probabilities of less
than a mile are 7-17%, which is more than this morning, but still
overall low. Will keep out of the forecast for now, but something to
consider.

&&

.MARINE...
Wave heights have decreased and small craft advisories have
expired this morning. We may have a short window Monday night into
Tuesday morning when wind waves could be steep enough to approach
small craft advisory conditions over the southern outer waters.
Also, winds become southerly and increase by Wednesday evening in
advance of the next weather system, possibly producing steep enough
waves in the northern outer waters to reach close to small craft
advisory conditions. Additional mid to long period westerly and
northwesterly swells are anticipated for mid to late week.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Cold Weather Advisory from 3 AM to 8 AM PST Tuesday for
     CAZ112-113-115.

NORTHWEST CALIFORNIA COASTAL WATERS...
None.
&&

$$

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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png