Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 211139

National Weather Service Eureka CA
439 AM PDT Mon May 21 2018

.SYNOPSIS...We may have a brief break for coastal marine stratus
and interior thunderstorms for today. However, they will return to
the area from Tuesday through Friday.


.DISCUSSION...We are finally getting a brief break in the stagnant
pattern. We have a weak upper level low over southern CA. This
gives us a northerly upper level flow ushering in drier air into
NW California. What this means that we will see a break from the
persistent coastal marine stratus and inland thunderstorms for the
day. Models are hinting on mostly sunny skies over Del Norte
Coast. For Humboldt Coast, we will see marine stratus trying to
break up, and may see a few peeks of sunshine this afternoon.
With the drier air in place, conditions will not be conducive for
thunderstorm developments over interior mountains for this

Enjoy what you have today, because it will not last long. Do
expect marine stratus to return to the coast tonight. Models are
hinting coastal areas to be saturated in the boundary layer from
Tuesday through rest of the work week, courtesy of the return of
the onshore flow. With increase in moisture, potential for
thunderstorm development will return to the interior mountains
from Tuesday through Friday. On Thursday and Friday, a well-
organized cutoff lows will approach the area. With this weather
feature, think that the most favorable conditions for convection
over interior mountains will be on Thursday and Friday.


.AVIATION...A moderately deep and persistent marine layer has
pushed well into the interior again. The clouds were covering nearly
all of Humboldt county and extended into central and eastern Trinity
county. The interior low cloud cover will bust up with daytime
heating and mixing. The solid MVFR ceiling at coastal terminals this
morning should lift up and become more broken this afternoon. The
daytime mixing and drying for sites at the coast will be fighting
against a moist onshore flow which will likely lead to more cloud
generation this afternoon. Thus expect MVFR ceilings to quickly
spread back over the coastal plain and terminals by this evening.
There is a potential for ceilings dropping below 1000 feet as we
head into the early morning hours of Tue. Confidence at this point
is not high.

For KUKI, skies were clear through the night. Low clouds were banked
up over the coastal ranges to the west. Northerly flow offshore is
typically not a favorable setup for stratus at KUKI, unless the
layer deepens and pushes over the coastal ranges. The marine layer
is not expected to deepen considerably through the forecast period.
Thus, VFR is expected for KUKI today through tonight.


.MARINE...Moderate northerlies offshore will generate steep
northerly wind waves today and tonight. Short period seas will most
likely reach 10 ft or more by this evening. Expect rough conditions
to last into Tue before northerly breezes and steep seas settle
down Wed and Thu.


NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 5 PM PDT Tuesday for PZZ450-455-470-



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