Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 112240
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
240 PM PST Tue Dec 11 2018

.SYNOPSIS...A weak system will bring some light rain to the area
this evening and overnight. Wednesday and Thursday will see dry
weather. The next system bringing rain and mountain snow is
expected Friday with additional systems on Sunday and Tuesday.

&&

.DISCUSSION...Currently a weak frontal boundary is bringing some
light rain to Del Norte and Humboldt counties. This will continue
to spread south across the area this evening and overnight.
Rainfall amounts will generally be light, totals are expected to
range from 0.5 inches in the Del Norte Norte mountains to a few
hundredths in southern Mendocino county and Eastern Humboldt
county. The Humbodlt Bay area is expected to see around 0.15
inches.

Wednesday high pressure is expected to build into the area.
Coastal areas will likely be clear fairly early, but inland areas
may be slow to clear. Wednesday night will be the coldest night,
although it is hard to say at this point if we will see frost in
the coastal areas. There may be too much lingering moisture. There
is also a weak system moving by to the north of the area that may
bring some high clouds to the area. These could linger into
Thursday.

Thursday night the next cold front starts to approach the area.
This will increase southerly winds and they are expected to peak
Friday morning. There are still some timing differences in the
models, the 12Z ECMWF has the front keeping the rain offshore
until late morning, while the NAM and the GFS bring it onshore in
the north early in the morning. have trended the forecast towards
a slightly slower solution, but confidence is low on the exact
timing. Snow levels are expected to range from 4,000 to 4,500 feet
in eastern Trinity county. This will likely impact the Scott
Mountain pass on Highway 3. Winds are expected to stronger with
this system, gusts around 45 mph are expected on the ridges. A
wind advisory may be needed, but for now it looks borderline.

Saturday is looking fairly dry in the morning, but a weak warm
frontal boundary could bring some light misty rains to the area in
the afternoon. Saturday night and Sunday morning there may be
some periods of rain ahead of the next cold front. Currently the
GFS and ECMWF show the heaviest rain moving into the area Sunday
afternoon as the cold front moves through. The models are both
showing this system moving through quickly making river flooding
not too likely. Some small stream or urban area flooding is
possible due to the heavy rainfall rates. Winds are expected to
be strong with this system, but models are still struggling with
the exact track of the low pressure offshore.
 with several inches of snow.
Next week the models are divided on how far south the system
brings rainfall. The ECMWF brings a significant amount of rainfall
into the area while the 18Z GFS keeps it just north of the border
in Oregon. This will need to be watched as it gets closer. MKK

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals through tonight, though rain has already started to move
in at the coast and impact the coastal terminals. Overall, rainfall
is expected to be light to moderate, but a heavier shower cannot be
ruled out. Additionally, MVFR to IFR conditions may occur with any
heavier showers that pass over the terminals. Low-level wind shear
will be possible at KCEC this afternoon and evening as the front
arrives, but the other terminals are expected to experience only
marginal low-level wind shear.

&&

.MARINE...Seas will build tonight as another westerly swell moves
through the coastal waters, with seas peaking early Thursday
morning. Small Craft Advisories are in place for each coastal zone
and tried to be timed to begin as the westerly swell moves through
the waters. Northerly winds will develop behind the front tonight
and into Wednesday, then shift to southerly early on Thursday as
another system is set to approach on Friday. Seas will gradually
wane through the day on Thursday as a west to northwest swell begins
to move through the waters early Friday morning. Southerly winds
will increase first over the outer waters Thursday and move into the
inner waters by Friday. As a result, short period southerly wind
waves will build across the coastal waters through Friday. Combined
seas will climb over 20 feet in the outer waters during the day on
Friday. Otherwise, yet another westerly swell will move through the
coastal waters Saturday night and into Sunday, with seas forecast to
peak around 23 feet Sunday night.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 6 AM Wednesday to 9 PM PST
     Thursday for PZZ450.

     Small Craft Advisory from midnight tonight to 9 PM PST Thursday
     for PZZ470-475.

     Small Craft Advisory from noon Wednesday to 9 PM PST Thursday
     for PZZ455.

&&

$$

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