Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 202300

National Weather Service Eureka CA
400 PM PDT THU OCT 20 2016

.SYNOPSIS...High pressure will remain over the region through
Saturday resulting in mostly dry weather with seasonal
temperatures. A wet weather pattern will develop on Sunday and
early next week.


.DISCUSSION...High pressure will remain over the area through
Saturday and provide mostly dry weather conditions with seasonal
temperatures. 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 tonight through Friday morning as this weak front
approaches the Oregon coast. Some light misty drizzle along the
Humboldt county coast may also occur as winds become northerly
over the coastal waters behind the front. This wind shift looks
to hold off until early Friday morning. Confidence there will be
any measurable precip is low. If rain or drizzle does occur,
expect only a few hundredths.

Ridging and offshore flow will return later on Friday into Friday
night and expect drying and clearing. The ridge and offshore
wind flow will hold into Saturday and dry conditions will
continue to prevail. A front will approach late Saturday night and
should bring some light showers to the northern most portion of
the forecast area by day break Sunday. 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. I
have seen many times when both models have been in great agreement
4-5 days out, yet the front either slows down or speeds up.
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. 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, but
none of the passes across Northwest California will be impacted by


.AVIATION...VFR to MVFR conditions and light winds will continue
at KCEC and KACV through this evening. The lower conditions will
be due to reduced ceilings. VFR to IFR conditions will occur at
KCEC and KACV overnight. The lower conditions will be due to
reduced ceilings and/or visibilities due to stratus and/or patchy
fog occurring at times. VFR conditions and light winds to calm
conditions will occur at KUKI through Friday Winds will become
light to calm overnight at KCEC and KACV.


.MARINE...Light winds will continue across the waters this week
as a high pressure ridge shifts westward and a cold front
approaches the region maintaining a weak pressure gradient across
the area. The aforementioned cold front will move across the
region Friday night and Saturday. The winds will increase along
the front Friday and Saturday. A westerly swell will propagate
across the waters Friday through early next week. Small craft
advisories will be in effect across all the waters Friday night
through Saturday evening due to the elevated westerly swell.


.EKA Watches/Warnings/Advisories...
Small Craft Advisory from 9 PM Friday to 9 PM PDT Saturday
for PZZ450-455-470-475.



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