Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 162345
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
345 PM PST Mon Jan 16 2017

.SYNOPSIS...High pressure continues to bring mostly clear and dry
conditions to the area this afternoon. The next system starts to
move into the area Tuesday afternoon. This will bring a period of
heavy rain on Wednesday. Additional systems are expected later in
the week.

&&

.Short Term...Water vapor shows the next system approaching the
area. High clouds are expected to start moving in over the area
tonight into Tuesday morning. Chilly temperatures are still
expected tonight, although likely not as cool as last night with
the increased cloud cover.

Tuesday afternoon rain is expected to start over the higher
elevations and in Del norte county as a warm front moves over the
area. Early Wednesday morning rain will start to taper off as the
warm moves to the north of the area. Winds will increase as the
warm front moves onshore and remain elevated in the warm sector
behind the warm front. There will likely be a break in the rain
Wednesday morning, although the farther north you go the shorter
the break. Crescent City may not see much of a break at all. The
front is expected to move through Wednesday afternoon. There is
expected to be a period of heavy rain where 1 to 2 inches will
fall in just a few hours. This will likely cause minor flooding
of low lying areas and street flooding. Winds will peak with the
front as well. Gusts to 35 mph are expected in Eureka with a few
gusts 45 to 55 mph at elevation along the coast. A wind advisory
will likely be needed along the Del Norte county coast and over
the higher elevations of Humboldt and Del Norte counties, but will
wait for a few more model runs to see if they remain consistent.
Rainfall totals with this initial system are expected to range
from 1.5 to 5 inches. The highest amounts will be over the higher
elevations in Humboldt and Del Norte county with the lowest
elevations around Humboldt Bay and in southern Mendocino county.
This is not expected to be enough rain to cause much flooding on
the main stem rivers. Snow levels will be high in most areas with
this front, mainly over 6,000 feet. There is a possibility some
cold air will get trapped in the eastern valleys of Trinity county
and this will need to be watched.

Wednesday night showers are expected behind the front. A few
thunderstorms are possible with the best chance being over the
waters. Held off on adding them to forecast though due to low
confidence. Snow levels will fall once the front passes Wednesday
evening to around 3000 feet by Thursday morning. At this point
showers look fairly minimal and expect we will only see a couple
inches of snow. Thursday there will likely only be a few showers
around and otherwise mainly dry and partly cloudy. MKK

.Long Term...(Thursday night through Monday) Another front is
expected early Friday morning. This system looks colder than
earlier in the week. Significant snow is possible as low as 3500
feet with this system. Behind this front on Friday and Saturday
showers are expected to bring snow levels progressively lower to
around 2500 feet. Sunday another front is expected and may bring
snow to 3000 feet. Showers are possibler even lower on Monday.
Confidence is low on the details, but it appears we are heading
into a stretch of colder weather. MKK

&&

.AVIATION...Another nice and sunny day across NW California
today. Crescent City and Arcata airports were in VFR conditions
all day today. There were periods when Arcata went down to
MVFR/IFR/LIFR last night due to passing fog bank or low clouds.
Ukiah remained in low clouds and fog, or LIFR category, until mid-
morning.

High clouds will be moving into NW California tonight. Do expect
the rain showers to move into Crescent City tomorrow morning,
along with increasing winds. Do bring in 35 kt low level wind
shear by tomorrow afternoon, along with steady rain and reduced
visibilities and ceiling. For Arcata, bring in vicinity showers by
tomorrow afternoon. Should be another nice day in Ukiah. /RCL

&&

.MARINE...Active pattern for the marine weather. Light and
variable winds will give way to south wind this evening. The south
winds will increase late tonight as the southerly pressure
gradient off the NW California waters tightens. By tomorrow
afternoon, will have south wind increasing to 25 to 35 kt with
higher gusts with the approach of a weather front. The strongest
winds will be over the outside waters. The strong south winds will
persist through Wednesday afternoon. The weather will push inland
Wednesday evening, and that will allow the winds to become
southwesterly and drop off. With the primary storm track remaining
north of the area, winds will remain primarily from the west to
southwest through next weekend.

With persistent onshore winds, the seas will remain elevated through
the forecast period. Wave heights of around 6 to 7 ft today will
increase to 11 to 14 ft by tomorrow afternoon. The wave period will
be around 14 seconds. Right now, there is a low pressure system off
the coast of Japan. This system will track east across the Pacific
Ocean, and reach East Pacific on Friday. With a long westerly fetch,
this system will bring in high magnitude swell to NW California
coastal waters. Models are suggesting 25 ft or higher with wave
period of 18 seconds. This has potential to produce high surf
conditions along the coast. /RCL

&&

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

     Small Craft Advisory from 9 AM to 3 PM PST Tuesday for PZZ470.

     Gale Warning from 3 PM Tuesday to 3 PM PST Wednesday for PZZ470.

     Small Craft Advisory from 9 PM Tuesday to 9 AM PST Thursday for
     PZZ455.

     Small Craft Advisory from 9 AM Tuesday to 3 AM PST Wednesday for
     PZZ475.

     Gale Warning from 3 AM to 3 PM PST Wednesday for PZZ475.

&&

$$

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