Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 211209

National Weather Service Eureka CA
509 AM PDT FRI OCT 21 2016

.SYNOPSIS...High pressure will remain over the region and slowly
weaken through Saturday resulting in mostly dry weather and
gradually cooling temperatures. A wet weather pattern will
develop on Sunday with another dose of moderate rain expected


.DISCUSSION...High pressure will remain over the area through
Saturday although weakening slowly while heights and thickness`s
fall. The only fly in the ointment will be a weak front that has
been spreading considerable cloud cover over Del Norte county
today. Isolated light showers will be possible over Del Norte
county this morning as this weak front approaches the Oregon
coast. Some light misty drizzle along the Humboldt county coast
has occurred early this morning as winds have become northerly
over the coastal waters behind the front. Saturday looks pretty
nice along the coast as some offshore wind flow develops ahead of
another weak front approaching late Saturday.  Better chances of
rain with this front will probably hold off until Sunday
afternoon. The flow aloft will become southwest and parallel to
the boundary which will slow it down. A mid level short-wave
should push the boundary toward the coast in the afternoon. A wet
weather pattern will begin to emerge by Sunday night as an upper
trough digs southward offshore of the West Coast. The timing of
the rain is still somewhat sketchy, so did hit the precip chances
hard for Sunday night. Plus, the rainfall amounts with the first
front on Sunday or Sunday night does not look to be all that heavy
and the duration will not be long. The short duration and low rain
amounts should minimize impacts. A more potent and juicier front
will bear down on Northwest California on Monday. Both the GFS and
ECMWF were in decent agreement with the bulk of rain coming in
during the afternoon on Monday and Monday night.  Confidence is
high we are going to see a good soaking with 1-2 inches of rain by
daybreak Tue, just not confident in the exact timing yet. The rain
with this front will probably have more impacts, however flooding
is not anticipated at this time. This will need to be closely
monitored. We never really know for sure until the rain starts
hitting the ground and accumulating. Showers will probably linger
on Tuesday. Forecast models still having some difficulty resolving
precip amounts and timing for next week. It is interesting to
note that the models were in fairly decent on the 500mb flow
pattern going into mid next week. Both show a broad positively
tilted upper trough offshore the West Coast with broad flat
ridging over our area. Yet the forecast for precip varied greatly.
The GFS was quite wet while the ECMWF was much drier. The GFS is
obviously entraining much more moisture into the trough than the
ECMWF. Confidence is not high here with either solution, so have
kept only a chance of rain. The forecast becomes much uncertain on
Thu, though both models indicate little or no rain. Thus kept
precip chances near climo. Good thing is these storms will be mild
in terms of low snow levels. Granted the levels will come down a
little, but mostly rain is expected and only snow along the
highest peaks.


.AVIATION...Low ceilings near 600 feet with 2 to 5SM visibilities (occasionally
lower) persist at KCEC. Even lower ceilings persist at KACV, but
visibilities have been more variable. This trend will continue
through mid morning at both locations, before improving slightly
after that, with a return to IFR or lower conditions likely Friday
night. Meanwhile, at KUKI, light winds and VFR conditions will
prevail. /PD


.MARINE...Light winds and seas will continue through this afternoon. A weak
cold front crossing the region Friday night and Saturday will cause
an increase (somewhat) in the pressure gradient. This will allow
winds and seas to build some. A small craft advisory is already in
effect for all marine zones during this period of time and this
looks good, so we`ll maintain the current headlines as is. Things
will improve by Sunday and continue for the remainder of the
forecast period. /PD


.EKA Watches/Warnings/Advisories...
NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory from 9 PM this evening to 9 PM PDT Saturday
     for PZZ450-455-470-475.



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