Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 182201
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
301 PM PDT Sat Aug 18 2018

.SYNOPSIS...Hot and dry conditions continue across the interior
with cooler conditions along the coast. Smoke from active
wildfires in California and southern Oregon will persist across
the region during the upcoming week.

&&

.DISCUSSION...A period of east to northeast winds occurring
during the past 24 hours allowed smoke to drift south and west
across most of the CWA. Recent visible satellite imagery shows
the thickest smoke was located over Del Norte, northern Humboldt,
Trinity, and eastern Mendocino counties. As a result, an Air
Quality Advisory is in effect for Hoopa, Orleans, Weitchpec,
Lewiston, and Trinity Center through Sunday. In addition, a hot
antecedent airmass will continue to be tempered somewhat by areas
of thicker smoke.

Model guidance is developing a mid to upper-level trough along
the California and Oregon border starting Monday, but some
uncertainty exists in the exact placement of the disturbance.
However, MUCAPE around 800 J/kg and pwats nearing an inch are
forecast to accompany this feature. Despite the uncertainty in
the placement of the trough, confidence was sufficient to
introduce a slight chance of thunderstorms over interior Del Norte
county. Otherwise, early to midweek temperatures are forecast to
be cooler across the interior in response to the upper-level
disturbance, with afternoon highs in the 80s to low 90s.

&&

.AVIATION...Smoke has been the main forecast issue for all of the
local airports today. Conditions have improved along the coast with
only slight visibility reductions being noted at ACV early this
afternoon. Across the interior, conditions remain IFR/LIFR due to
reduced visibilities and near surface opaque smoke layers. As we go
through the afternoon slightly enhanced mixing will allow
visibilities to increase to MVFR/IFR.

As we go into the evening, the next forecast issue will be the
return of coastal stratus. As of early afternoon, one batch of
stratus has been hugging close to the Mendocino coast line. With
strong northerly winds don`t expect that area of stratus to round
the cape. However, a second batch of stratus is located
approximately 60 nm off the coast and as winds become more
northwesterly this stratus may approach and expand along the
Humboldt Coast. High resolution model guidance indicates IFR/LIFR
conditions will develop at ACV by late this evening and persist
through Sunday morning. Conditions at CEC are a bit more uncertain
as model guidance keeps CEC clear. With southerly winds developing
at CEC by late tonight though expect some of the coastal stratus to
advect north along the coast, eventually impacting CEC. /WCI

&&

.MARINE...The brisk northerly winds and steep seas will continue to
impact the waters through at least Monday morning. While winds will
be lighter across the inner waters seas will remain steep and
hazardous. Model guidance continues to show northerly winds
decreasing in intensity on Monday which will also allow seas to
begin to diminish. Light southerly winds develop along the Mendocino
coast by Tuesday morning as a low pressure center moves offshore
otherwise,  light to moderate northerly winds will persist through
the end of the week. /WCI

&&

.FIRE WEATHER...Winds will diurnally fluctuate between onshore
during the afternoon, followed by offshore overnight. The strongest
offshore winds, with gusts to 25 mph, are forecast to occur
across the ridgetops of interior Del Norte county through Monday
night. Otherwise, hot and dry conditions, with temperatures in the
90s to low 100s will continue through Sunday across interior
northwestern California. In addition, an isolated thunderstorm
will be possible Tuesday evening over interior Del Norte county.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 5 PM PDT Sunday for PZZ450.

     Small Craft Advisory until 3 PM PDT Monday for PZZ470-475.

     Small Craft Advisory until 5 AM PDT Monday for PZZ455.

&&

$$

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