Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 112206

National Weather Service Eureka CA
206 PM PST Mon Dec 11 2017

.SYNOPSIS...Mainly dry conditions, accompanied by mild afternoons
and cool nights, will persist during the next 7 days.


.DISCUSSION...A compact upper low positioned offshore from WA was
in the process of moving north along the west side of a WRN CONUS
ridge Monday afternoon. An increase in midlevel southerlies
associated with the wave was aiding in transporting smoke produced
by wildfires in SRN CA northward across the Redwood Coast.
However, model guidance during the next 24 hours shows midlevel
flow becoming northerly over the CNTRL/SRN CA coast, which will
allow smoke to clear the region during Tuesday into Wednesday.
Otherwise, high level cirrus is forecast to increase during
midweek, resulting in a decrease in nocturnal surface radiational
cooling and cold air drainage into area valleys. Thus, overnight
lows are expected to gradually moderate. By Friday, model guidance
shows the ridge over the west coast breaking down as a weak upper
impulse moves west across the region. This process will allow an
increase in westerly moisture flux to develop over the OR/WA
coast during the weekend into early next week, the brunt of which
is forecast to be too far north to yield significant rain
probabilities over NWRN CA.


.AVIATION...A persistent strong ridge will continue to result in
VFR conditions at all terminals. Some smoke aloft and high clouds
have been noted at both ACV and UKI today due to the fires down
south. Some interior river valleys will also see patchy fog again
tomorrow morning however it will clear by late morning. /WCI


.MARINE...Quiet marine weather pattern will continue through
Tuesday. A strong high pressure remains over western North
America, while the main storm track remains offshore. By middle of
the week, a thermal trough is forecasted to develop along the CA
coast, and this will enhance the northerly pressure gradient over
NW CA waters at that time. A strong high will build north of NW CA
water by the end of the work week, and this will further tighten
the northerly pressure gradient in the area.

Light and variable winds in NW CA coastal waters through Tuesday.
North winds will start to increase on Tuesday night to around 10
to 20 kt. North winds will further increase on Friday to 15 to 25
kt, before diminishing through the weekend.

Through Tuesday, we will just be seeing decaying west swell,
giving us a combined seas of around 5 to 7 feet. On Tuesday night,
looks like we will have a fresh NW swell coming in, with a
developing short period wind wave. Combined seas will be around 7
to 9 feet. The short period wind wave will increase later this
week as the northerly winds strengthen.

There is a slight potential for sneaker wave late Tuesday
afternoon through Tuesday evening. However, there is some forecast
uncertainty with this. The long period swell is marginal in terms
of its energy. The wave period will be decreasing, from 18 to 15
seconds. Meanwhile, the wave magnitude will increase from 1 to 5
feet. In addition, the short period wind wave may erode the energy
provided by the long period swell. The short period wave is
forecasted to be around 3 to 6 feet. The higher the magnitude of
the wind wave, the less likely the threat for sneaker wave. Due to
these conflicting indicators, confidence is low in determining
the potential for sneaker wave, but the threat does exist at this

There is no marine hazards in effect at this time. /RCL




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