Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 221133
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
433 AM PDT Fri Mar 22 2024

.SYNOPSIS...A front moving onshore this morning will bring rain
and gusty winds. There will be a brief break in the weather this
afternoon. Showers and isolated thunderstorms are expected this
evening and Saturday with snow levels falling to around 4000 feet.
Drier weather is expected Sunday with additional wet weather
expected next week.

&&

.DISCUSSION...This morning a frontal boundary is just off the
coast as of 3AM. This is expected to bring a round of locally
heavy rainfall this morning. Warm air advection ahead of this
front is bringing warm air and snow levels look to be around 5,000
feet. Most of the precip with this front is expected to fall
ahead of the cold air. Breezy winds are expected with this front
as well. Gusts of 40 to 45 mph are expected over the higher
terrain in the coastal counties with lighter winds farther inland.
A wind advisory may be needed, but for now it looks like it will
be a brief period of stronger winds mainly associated with the
front. Some lighting has been reported just off the coast this
morning with the front. A strike or two may make it onshore this
morning.

Once the front moves onshore and past the area this afternoon
there will be a brief break in the rain and wind. This evening
the main upper level low moves by to the northwest of the area and
stalls just off the ORegon coast. This low is expected to remain
there slowly weakening through Saturday before dropping south
Saturday night and out of the area by Sunday morning. This will
bring more rain and wind to the area. With the low closer by the
area there will be colder air aloft and this will increase the
potential for thunderstorms tonight and Saturday as well as
lowering snow levels. Snow levels are expected to fall to around
3500 to 4000 feet by early Saturday morning. This expected to
impact highway 3 at Scott Mountain and highway 36 at South Fork
Mountain and near the intersection of highway 3. The best chance
for snow looks to be Friday night into Saturday morning. Four to
six inches is possible on hwy 36 and up to 10 inches of possible
on Scott Mtn. So have issued a winter weather advisory to
highlight this. Gusty winds are also expected with these showers,
but the support aloft diminish as the low weakens tonight. There
is around 40 to 45 kt at 850 MB over Humboldt and Del Norte
counties, but not all of this is expected to mix down so have held
off on issuing a wind advisory.

Once this low moves out of the area early Sunday drier is
expected. This has the potential to allow temperatures to drop
enough for frost, but it looks like there will be too much
moisture remaining in place. Monday and Tuesday a couple of weak
systems are expected but the main impacts are expected to be some
light rain and increased clouds. If there is a long enough break
between these systems there could be some additional potential for
frost.

Tuesday night or Wednesday a stronger system is expected to bring
moderate to heavy rain and stronger winds to the area once again.
Currently the ECMWF EFI is highlighting this with 0.5 to 0.6 for
the strong winds and heavy rain. Additional systems are possible
beyond this.

&&

.AVIATION...Low-level wind shear is the top concern for this
forecast. Hi-res models indicate that we could see 40 KTS as low
as 1500- 2000KT from the south from the low-level jet ahead of the
approaching cold front. The onset and cessation of these stronger
winds aloft will be earlier along the coast, and later farther to
the east at KUKI as the low-level jet axis and cold front keep
moving east. Surface wind near thunderstorms or more robust
showers. It would not be shocking to see some wind gusts pushing
30 KTS locally near stronger storms and showers. Visibility may be
noticeably lower as the line of showers/storms moves through as
well. Two main peaks to wind speeds/gusts will occur in the short
term. The first is ongoing this morning with strong south winds
occurring along and ahead of a cold front advancing east. Then,
after a lull by late morning/early afternoon behind the front,
south southwest winds will increase again, ahead of another re-
enforcing cold front. The south wind could very well remain quite
gusty tonight, especially for KCEC, with south winds over 30KTS
from time to time completely in the realm of expectations. Thunder
is not completely out of the question this morning, but better
chances come this evening tonight. Nonetheless, leaning away from
adding thunder at this time as chances still look low enough to
keep out of the forecast for now.

&&

.MARINE...Current Small Craft Advisory continues to look solid. Two
main peaks to wind speeds/gusts will occur in the short term. The
first is ongoing this morning with strong south winds occurring
along and ahead of a cold front advancing east. We could be pushing
gale force gusts in parts of the norther outer waters and near Cape
Mendocino, especially. Also, wind gusts near some of the strongest
convection could be pushing 30-35 KTS or so as well. Then, after a
lull by late morning/early afternoon behind the front, south
southwest winds will increase again, ahead of another re-enforcing
cold front. Once again wind gusts could be pushing gale force
especially in northern outer waters and off the coast of Cape
Mendocino. Extended the advisory for another 6 hours into Saturday
evening except for northern inner waters due to steep waves
lingering. With the new swell arriving late in the weekend, more
small craft advisories will be quite possible, and perhaps hazardous
seas by Sunday evening, especially over southern outer waters.
Expect another mid to long period swell to arrive Tuesday
night/Wednesday.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Winter Weather Advisory from 11 PM this evening to 11 PM
     PDT Saturday for CAZ107.

     Winter Weather Advisory from 11 PM this evening to 11 AM
     PDT Saturday for CAZ108.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 6 PM PDT Saturday for PZZ450.

     Small Craft Advisory until midnight PDT Saturday night for
     PZZ455-470-475.

&&

$$

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