Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 021247
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
447 AM PST Tue Mar 2 2021

.SYNOPSIS...Dry weather, along with near-normal daytime and cool
nighttime temperatures, will occur across northwest California
through Wednesday. There is the potential for strong winds
Thursday with rain moving in late Thursday or Friday. The
potential for rain will continue through Monday.

&&

.DISCUSSION...The upper level low well off the coast of central
CA continues to drift south bringing offshore flow and mostly
clear skies to northern CA. This has brought chilly temperatures
across the area this morning. Have expanded the frost and freeze
products as temperatures have ended up colder than expected. This
afternoon temperatures are expected to be similar to yesterday
with the coast in the middle 50s and the interior valleys in the
60s.

Tonight an upper level trough starts to slowly approach the area.
This will likely shift flow to more onshore at the coast bringing
stratus onshore to the Humboldt coast and should keep temperatures
from getting as cold. Confidence is low on this as the night
satellite shows it to be fairly broken up. Despite this, the HREF
shows fairly high probabilities of low clouds near the coast.
Inland areas of Mendocino and Lake counties will likely see frost
or freezing conditions once again. This afternoon coastal stratus
and onshore will likely keep coastal areas cooler than today.
Inland areas seeing mostly clear skies and temperatures are
expected to be similar to today.

Wednesday evening and overnight southerly winds will start to
pick up along the Humboldt and Del Norte coasts as the upper level
trough and associated frontal boundary approach the area. This
should help keep temperatures above freezing. The southerly flow
may help to clear out clouds at the coast. Winds will continue to
increase on Thursday and Thursday night. Currently it looks like
the winds will peak early Friday morning just ahead of the front
with gusts of 40 to 50 mph on exposed coastal headlands and
ridges. Higher gusts are possible, but there are some questions on
how well the winds will mix down. There is the potential these
will impact the Mendocino coast as well, but confidence is lower
on this and it will be closer to midday that winds will peak.
Overall the ensembles are in good agreement on this system moving
onshore and the biggest source of uncertainty appears to be on the
timing and exact strength. This front is also expected to bring
rain and high elevation snow. There is a chance the rain will
start as early as Thursday in the north, but the better chances
for precipitation will be with the main front on Friday. The
ensembles are still showing quite a bit of uncertainty on the
timing and this is resulting in only chance pops. Despite these
low pops there is the potential for a period of moderate to heavy
rain on Friday. At this point it doesn`t look it will convective
and rainfall rates are not expected to be high enough to impact
burn scars. Snow levels are generally expected to range from 4,000
to 5,000 feet, but these could be lower early on and this will
need to be watched as it gets closer.

Over the weekend some of the ensemble solutions, mainly the GEFS,
are showing a colder trough moving over the area. There are also
a good number of them, keeping the area warmer and drier with a
slower and weaker trough. If the colder and wetter solutions
verify there is the potential for snow to impact the higher passes
on Hwy 299, 36, and 3. However, if the slower solutions verify
only some very light rain or snow is expected for the weekend.

The wet pattern generally looks to continue into next week,
although there is a lot of variability in the details. There are a
number of ensemble solutions that could bring some low elevation
snow as well as some that bring a much warmer solution. MKK

&&

.AVIATION...Scattered high clouds drift over Mendocino, Lake and
Trinity counties this morning while valley fog has formed in a few
inland valleys of Humboldt and Del Norte. Any low clouds should mix
out soon after daybreak, with widespread VFR conditions expected
through at least early afternoon. Stratus may develop offshore this
afternoon, and if it does, it should return to the coast this
evening and persist overnight...driving IFR to possibly LIFR
conditions at coastal terminals. Otherwise VFR and light winds
continue through the TAF period for areas farther inland.


&&

.MARINE...Light northerly winds around 5 to 15 kts continue
today, with a local max in the high teens developing off of Cape
Mendocino late this afternoon. A mid period NW swell continues to
fill in through tonight, when it should peak around 11 ft at 14
seconds, then decay through Wednesday.

A front is expected to approach the coast late this week, bringing a
slow moving, wide and robust band of southerly winds starting early
Thursday. These winds should efficiently build up short period
southerly seas by Thursday night, with heights in the low to mid
teens currently forecasted for the outer waters. Meanwhile, another
slightly longer period 10 to 12 ft NW swell should arrive on
Thursday and last through the weekend, bringing a chance of chaotic
combined seas in the high teens to low 20`s for Friday.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...Freeze Warning until 9 AM PST this morning for CAZ110-111-114-
     115.

 Frost Advisory until 9 AM PST this morning for CAZ103-112-113.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 6 AM this morning to 6 AM PST
     Wednesday for PZZ470.

     Small Craft Advisory from 6 PM this evening to 6 AM PST
     Wednesday for PZZ455.

     Small Craft Advisory from noon today to 6 AM PST Wednesday for
     PZZ450-475.

&&

$$

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