Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 312258
AFDEKA

Area Forecast Discussion
National Weather Service Eureka CA
358 PM PDT TUE MAY 31 2016

.SYNOPSIS...Well above normal temperatures will continue through
the end of the week across interior areas, with near normal values
along the coast. Isolated to scattered thunderstorms will be
possible across the interior over the weekend.

&&

.DISCUSSION...As expected, a building upper-level ridge of high
pressure aloft has brought well above normal temperatures and
mostly clear skies to much of the region. As of 3 pm, many
interior valley locations have reached well into the middle and
upper 90s, which is approximately 15 degrees above normal for the
end of May. Meanwhile, onshore flow has kept coastal temperatures
characteristically cool, with highs only a few degrees above
normal in the low to mid 60s. Regardless, those few extra
degrees, persistent sunshine, and only a modest breeze have
combined to create a pleasant day along the coast. These warm and
dry conditions will persist through the end of the work week as
the upper level ridge maintains its grip on the region, although
there will be minor fluctuations in high temperatures of around 5
degrees or so. Friday and Saturday appear to be the hottest days
of the week by the slimmest of margins, although this will hardly
be noticeable to the casual observer. Stratus will likely return
to portions of the coast overnight tonight, particularly in the
typical trouble spots around Humboldt Bay and along the Mendocino
coastline. There is some uncertainty as to just how long this
stratus will persist tomorrow morning, and just how much will
develop throughout the week, however it is likely that at least
some low cloud cover will develop along the coast most nights this
week.

Aside from the heat, the next item of interest for this week`s
weather will be the potential for thunderstorms, particularly over
the weekend and early next week. While a brief thunderstorm
remains possible in the mountains near Trinity Lake Wednesday as a
flat shortwave glances our region to the north, chances are very
low and any activity that manages to develop will quickly move
east of our area. Better chances for convection will likely
develop over the weekend and potentially last into early next week as
a cutoff low moves onto the California coast to our south. As this
low moves onto the coast, a plume of steep mid-level lapse rates
and modest moisture will overspread the region, resulting in
substantial instability with minimal inhibition by Sunday
afternoon and evening. Low-level moisture appears to be somewhat
limited, and current model soundings reflect this with deep
inverted-V soundings and high LCLs. Also, wind shear appears to
be somewhat limited with this particular low, i.e. around 15 to 20
kt of 0-6 km bulk shear, and storm organization and strength will
likely be hindered by this. Still, these parameters support the
possibility of scattered high-based thunderstorms across
primarily interior areas, particularly Sunday and Monday
afternoon/evening, potentially with some dry lightning across the
lower elevations in the valleys where precipitation will be
limited by evaporation. While the previously mentioned parameters
have been relatively consistent in models over the last few days,
there remains substantial uncertainty in the track of the
approaching low, and this will play a big role in the timing and
location of convection. /BRC

&&

.AVIATION...The gradient has weakened a bit allowing winds to drop
slightly. The short period seas have followed this trend. The long
period southerly swell has increased as expected to around 3 feet
at 15 seconds. This is mainly showing up south of Cape Mendocino,
but is expected to spread north tonight. The winds over the outer
waters are expected to remain in the 20 to 25 kt range through
Wednesday evening. This is a bit higher than previously expected
so we have extended the small craft advisory. Seas may stay up a
bit longer so the advisory goes through 3 AM Thursday. The inner
waters look to stay just below small craft advisory criteria,
although it may be borderline during the afternoons.

Thursday winds look to remain around 15 to 20 kt. Friday into the
weekend winds increase once again with near gale conditions across
the outer waters. The long period southerly swell will slowly
diminish by the weekend. MKK

&&

.MARINE...High pressure has squashed the marine layer down to
around a thousand feet today. This combined with offshore flow
kept the area mainly clear this morning. The only exception to
this was a small patch of stratus off Humboldt Bay and the area
south of Point Arena. This afternoon the clouds persist from Point
Arena south, but have completely dissipated around Humboldt Bay.

Tonight a very weak system moving into the Pacific Northwest may
change the wind fields enough to allow more stratus to form than
this morning. It may be similar to Monday morning where clouds
formed around Humboldt Bay and were slow to clear in the morning.
Also, the clouds south of point arena may push north, possibly as
far as Fort Bragg. These clouds are expected to clear all the way
to the coast on Wednesday, but it take until mid to late morning.
Winds will be fairly light through Wednesday. MKK


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 AM PDT Thursday FOR PZZ470.

     Small Craft Advisory until 3 AM PDT Thursday FOR PZZ475.

&&

$$

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