Clearlake Oaks, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

186
FXUS66 KEKA 302209
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
209 PM 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...Despite noticeable improvements to weather
conditions this afternoon, another period of wet weather is
expected by Tuesday night. In addition, a very cold airmass has
settled over the region behind the departing system. 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.


&&

.AVIATION...Interior valley fog has mostly lifted this afternoon
with clear skies across the region. NE offshore flow has kept the
coastal terminals clear as high pressure builds into the PNW.
Increasing northerly flow will largely keep marine stratus from
developing, but HREF probabilities still highlight slight chances
(30 to 50%) of <2000 foot cloud ceilings developing in and around
Humboldt Bay around sunset. Even lower chances are evident for the
Russian River Valley. High cloud cover will begin to descend from
the north early Tuesday in anticipation of another weak upper
shortwave and frontal system arriving late Tuesday evening.

&&

.MARINE...Winds are increasing downwind of Cape Mendocino as weak
high pressure builds into the region. A brief period of small
craft conditions is possible overnight in the southern waters as
wind gusts approaching 20 to 25 knots produce elevated wind waves.
Otherwise, seas will continue diminishing as westerly swell
energy decays. Wave heights are expected to fall to 5 to 8 feet
until midweek, when an upper shortwave dips into the PNW and
generates stronger southerly flow alongside a 10 to 12 ft mid-
period westerly swell. Uncertainty still surrounds the strength of
winds with this system, but confidence is increasing on a
stronger low level jet developing along the surface front. Wave
heights are forecast to remain above 10 feet as additional
westerly swells and elevated southerlies persist into the weekend,
especially in the northern waters.


&&

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

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 AM PST Tuesday for PZZ455-475.

&&

$$

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