762
FXUS66 KEKA 302301
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
301 PM PST Thu Jan 30 2025

.SYNOPSIS...Gusty south wind and rain will arrive overnight
through Friday. Snow will be restricted to the Trinity Alps. Rain
showers will continue into the weekend with gradually lowering
snow levels.


&&

.DISCUSSION...Mostly dry conditions have continued for one final day
today, but an approaching storm system will soon bring the area`s
first wetting rain since January 6th. A robust band of rain is
currently visible on satellite about 150 miles offshore. Wind has
already turned southerly ahead of the front and begun to increase.

Southerly wind will continue to build this evening, especially after
2000 through early Friday morning. Peak gusts along exposed ridges
of Humboldt and Del Norte will most likely reach between 40 and 55
mph, though high resolution models show poor mixing with few gusts
above 40 mph expected at lower elevations and along the coast.

Rain will begin behind the strongest wind, mostly occurring after
midnight through the day on Friday. Rain rates will be mostly
moderate with high resolution guidance giving less than a 10% chance
of any rates above 0.4 in/hour. This will help limit overall rain
impacts (see hydrology section below). Over the next 48 hours, the
most rain favored locations (high elevation, south facing slopes)
will most likely see between 1.5 and 2.5 inches of rain, with
locally higher amounts in the King Range. Lower elevations however
such as Humboldt Bay and the Russian River valley, will see much
lower amounts closer to 1.0 to 1.5 inches of rain. Lighter rain
showers are expected to continue through the weekend and even into
early next week. Most models are showing a second wave of enhanced
rain sometime around next Monday.

This first round of rain and southerly wind will promote a push of
warm air advection, which will generally raise snow levels above
5000 feet through Saturday. That said cold, dry air trapped around
the Trinity Alps combined with upslope cooling may allow for
localized snow level as low as 2500 feet tonight into early Friday
morning. This will bring period of inconsistent, wet heavy snow most
likely between 4 and 8 inches along highway 3 north of Weaverville.
1 to 3 inches is possible as low as Weaverville itself and along
Buckhorn Summit. 8 to 12 inches of snow should be expected around
Scott Mountain pass.

Snow levels will rapidly drop this weekend, especially Sunday into
early next week as much colder air moves in aloft. By Sunday night,
snow levels may drop as low as 1000 to 2000 feet, though uncertainty
remains very high depending on the exact depth of the trough aloft.
That said, roughly 50% of ensemble member currently support snow
levels down to 1500 feet by next Monday. As rain showers continue
into next week, this will likely allow for the lowest elevation
snowfall of the season so far with snow impacts possible along many
pass of Highways 101, 199, 299, 3, 36, and even 20 in Lake County.
Such low freezing levels will also bring the potential of
accumulating small hail along the coast. High resolution models show
low freezing levels and low level instability as soon as Sunday
afternoon and evening which could generate isolated small hail along
the coast. This potential will have to watched closely over the next
couple days.

Ensemble models consistently show (90%) rain showers continuing
through much of next week. Most ensemble members (80%) show a dry
period returning some time around February 5th. /JHW


&&

.AVIATION...Pre-frontal cloudiness continued to advance across the North Coast
today; mostly MVFR Cigs "marginally" impacted coastal airports.
Stratus into the Humboldt and Mendocino interior valleys was quite
abundant and persistent through out the day...with cloud tops as
high as 3000 feet. UKI began the early hours in IFR...then finally
reported Cigs into MVFR this afternoon. Tonight, the approaching
system will usher in pre-frontal significant winds at the surface
and above ground. Therefore, LLWS will be possible this
evening...especially at CEC and then ACV. Rain will precede the
frontal system...starting in the late evening/overnight. MVFR
conditions should prevail overnight but deteriorate into lower
categories Friday afternoon. /TA


&&

.MARINE...Mild conditions will continue for the rest of the
daylight hours today before the first of many storms in the changing
weather pattern enters our area causing deteriorating conditions.
Strong southerly winds are expected to increase to gale-force gusts
tonight up to 50kts by tomorrow morning. These gale-force southerly
winds are expected to build in fast, and die down just as quickly
after passing through the area with the tomorrow`s afternoon winds
being around 10-15kts with gusts under/at 20kts. Southelry winds
should switch to moderate northerly breezes around 20kts on Saturday
and continue through the weekend.

A series of swells will enter the coastal waters this weekend with a
westerly swell of 5ft@9s arriving Saturday early morning. An
additional northwesterly swell of 7-8ft@11s arriving Sunday and
persisting into the work week. Steep wind waves could create
dangerous conditions through the weekend due to the stong winds
mentioned above. All and all, a chaotic sea state is to be expected
from tonight through Tuesday afternoon.


&&

.HYDROLOGY...An approaching storm system will bring significant
rainfall to the area over the 48 hours. As mentioned above, 1.5 to
3.5 inches is expected to fall at high elevation within the first 48
hours with light rain showers into early next week. Rain will be
widespread throughout the area from Del Norte and Lake County.

While rain will certainly increase the risk of rocks and debris on
local roadways with areas of ponding waters, widespread flooding
impacts are unlikely. Dry weather for the last 3 weeks has left
soils receptive to more rain, which will generally reduce runoff.
Furthermore, rain amounts look moderate at best with few models
(less than 10%) producing peak rates much above 0.4 in / hr. Such
rates generally produce only minor impacts for our area.

In line with this thinking, the latest river forecasts do not show
any river sites reaching even minor flood stage. At most, they show
the Eel rive reaching monitor stage next with a 20% chance of minor
flooding along the Russian river. Even flashier creeks like Scotts
Creek in Lake County are not project to reach impactful levels this
weekend.

All that said, there is some potential for more hydrology impacts
early next weeks. Saturated soils form this weekend would generally
be more conducive to enhanced runoff. This period (around late
Monday) is also when most river forecasts peak. Though the currently
most likely rainfall is not expect to generate such impacts, the
possibility will have to be watched closely. /JHW


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Wind Advisory from 10 PM this evening to 4 PM PST Friday
     for CAZ102-104>106.

     Winter Storm Warning from 1 AM to 2 PM PST Friday for
     CAZ107.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 9 PM this evening to 3 AM PST
     Friday for PZZ450-475.

     Gale Warning from 3 AM to 1 PM PST Friday for PZZ450.

     Small Craft Advisory from 3 AM to 3 PM PST Friday for
     PZZ455.

     Small Craft Advisory until 9 PM PST this evening for PZZ470.

     Gale Warning from 9 PM this evening to 9 AM PST Friday for
     PZZ470.

     Gale Warning from 3 AM to 9 AM PST Friday for PZZ475.

&&

$$

Visit us at https://www.weather.gov/eureka

Follow us on Facebook and Twitter at:
https://www.facebook.com/NWSEureka
https://www.twitter.com/NWSEureka

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