Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 222311
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
311 PM PST Wed Nov 22 2017

.SYNOPSIS...Unsettled weather conditions will persist through
Thanksgiving day with cloudy skies and light to moderate rain. A
slight reprieve from the rain will occur Friday and early Saturday
before yet another storm system brings rain back to the area
Saturday morning through early next week.

&&

.DISCUSSION...Precipitation has continued today across the northern
half of our warning area and will persist through tomorrow. Latest
radar trends continue to show an increasing trend in precipitation
intensity and coverage across the coastal waters with a general
motion towards the coast. This precipitation is associated with a
moderate atmospheric river (AR). This AR was oriented north of our
area today however it has begun to weaken and move farther south.
This tropical moisture will continue to be aimed at our area tonight
through Thanksgiving day before the cold front eventually clears
our area late Thursday night. The passage of the cold front will
setup a dry day on Friday with highs in the upper 50`s to low 60`s
across the region.

The GFS and ECMWF have come into better agreement today regarding
the timing of this weekends storm system with rain returning early
Saturday morning and sticking around the rest of the weekend.
However, the GFS and ECMWF have not come into better agreement
regarding the intensity, the ECMWF now depicts a much wetter
solution than the GFS (which less than 24 hours ago was the exact
opposite). Due to the low consistency from run to run have gone
with the middle ground of the solutions. Strong winds especially
over the higher terrain will also be possible late Saturday night
and into Sunday morning. These strong winds will probably last
less than 12 hours however a wind advisory may be required as we
get closer to the event. As the trough moves over the area much
colder air aloft will return to the region which will lower snow
levels down to around 3500 feet potentially even lower. It is
still a bit too far out to put snowfall totals with this system
however some of the higher highway passes may be impacted Sunday
night and Monday. Drier weather is expected next week once the
trough clears the area on Tuesday. /WCI


&&

.AVIATION...Concerning airports/airfields: A shield of clouds
steadily advected into Northwest California today, and is
associated...and out ahead of a somewhat weak cold front boundary.
Diverse types and levels of the cloudiness persisted through the
day, but was mostly mid-high clouds. The LLWS threat weakened in
the early afternoon, but may reconsider LLWS at CEC in the late
evening.

Coastal Air Terminals: Cigs remained VFR with VIS briefly dipping
into MVFR and a few light sprinkles in the morning. A rain band
slightly intensified offshore in early afternoon. The 1 PM
Reflectivity radar image showed rains sliding onto the coast,
producing light rain from EKA-ACV-CEC. The rain chances will
definitely increase through late afternoon into evening. Model
guidance also indicating for conditions to possibly even lower into
IFR late tonight.

Interior mountain valleys: Fog and low Cigs remained settle over
some inland valleys from Tuesday evening until around noontime
today...especially at UKI. The UKI air terminal reported VIS & CIG
at 1/4 miles and 200 feet through much of the period. Afternoon VFR
conditions will slowly give way to approaching clouds and overnight
light rain. Expect low VIS in the morning, but Cigs may not be as
impactful as in the last couple of days. /TA


&&

.MARINE...Moderate southerlies will continue across the
norther outer waters tonight. These winds will continue to drive
steep southerly seas across the outer waters, which will combine
with both SW and NW swells to create a mixed and uncomfortable sea
state. Winds will begin to weaken on Thanksgiving and turn to the N
on Friday, allowing the steep southerly seas to settle. However, the
previously mentioned swells will continue to maintain elevated seas
throughout the waters through the end of the work week.

On Saturday, southerly winds will increase yet again as another cold
front approaches, with gales likely in the N outer waters. This will
bring the return of steep southerly waves, in addition to both a
fresh westerly swell and a long period northwesterly swell. In a
nutshell, seas will be large, mixed in both period and direction,
and hazardous to mariners late in the weekend. /BRC&SEC


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 4 AM PST Thursday for PZZ470.

&&

$$

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