Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 250226

Area Forecast Discussion
National Weather Service Eureka CA
726 PM PDT TUE MAY 24 2016

.SYNOPSIS...Showers and thunderstorms will continue through this
evening, then diminish overnight. Isolated showers over the
interior mountains on Wednesday, then dry a stretch through early
next week.


.UPDATE...Thunderstorms have tapered off more quickly than
expected so have trimmed back the thunderstorms in the forecast.
There is still the possibility of isolated thunderstorms for the
next couple hours, but it is more likely we will just see showers
and these are diminishing quickly. MKK




A rather active afternoon across the interior locations. Showers and
thunderstorms developed over the mountains in eastern Mendocino
County and Trinity County. These showers have produced frequent
lightning strikes, dime-size hails, and locally heavy rainfall.
These showers are considered ordinary convection, mainly caused by
daytime heating in a marginally unstable environment. Afternoon CAPE
is progged to be around 500 to 800 J/kg, which is not too
significant. Upper level winds are fairly weak, thus there is not
much steering for these showers and thunderstorms. These pop-up
thunderstorms are mostly stationary. Once they matured, the heavy
rain will drag the cold air aloft down to the surface, and thus
choking off the warmer air inflow into these thunderstorms, and then
lead to the demise of these showers and thunderstorms. However, new
cells will then develop on the leading edge of the cold pool induced
by the parent thunderstorms. The cycle will continue through early
evening, until the surface-based instability courtesy of daytime
heating is gone as the sun sets. Elsewhere across NW California,
turns out to be a fairly nice afternoon as sun shines through breaks
in the sky cover.

Expect mostly cloudy skies for tonight, and diminishing showers
overnight. Mostly sunny skies will develop on Wednesday as the
cutoff low moves across Southern California into the Four Corner
region, and a strong upper level ridge builds over Eastern Pacific
Ocean. Dry conditions will continue through the Memorial Day weekend
as the upper ridge remain in control over the area. Coastal areas
will see diurnal intrusion of marine layer overnight, and the
retreat of it during the morning. Highs will be in the mid 70s
inland, in the low to mid 60s along the coastal area.

Forecast confidence is above average. Very stable weather pattern
with NW-ly upper-level flow. Overall changes are minor. /RCL


Pressure gradients will tighten up the next 24 hours as
high pressure strengthens offshore. As a result, northerly winds and
short period seas will increase on Wednesday. Winds and seas will
increase further Thursday as the high pressure ridge strengthens and
thermal low pressure deepens over the interior. Small craft
advisories for both winds and seas have been hoisted for all waters
starting Wednesday afternoon and evening. The highest winds are
expected in the outer waters, and around Cape Mendocino and Pt St
George. Near Gale conditions are expected Thursday and Friday in
the outer waters and locally around Pt St George and Cape
Mendocino. /DJB


Marine clouds covered much of the Coast today. Conditions at
ACV & CEC airports dropped down into IFR-MVFR with some midday
clearing. by 2:30 pm low clouds had started reforming along portions
of the coast. Low clouds will probably continue tonight except for a
few local spots reporting VFR skies into the early evening.
Disturbances associated with an upper low may bring isolated showers
over the near coastal hills...but will be unlikely to impact ACV or
CEC`s terminals. Interior areas are quite different as enough moist
unstable conditions...associated with the upper low...have migrated
into the region thus producing a number of thunderstorms. This will
be a threat to inland airfields through the evening with thunder...
lightning...small hail and associated gusty winds.  /TA


     Small Craft Advisory from 4 PM Wednesday to 5 PM PDT Thursday
     FOR PZZ450-470.

     Small Craft Advisory from 2 PM Wednesday to 5 PM PDT Thursday
     FOR PZZ455-475.



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