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fxus66 keka 182258 
afdeka

Area forecast discussion
National Weather Service Eureka California
258 PM PST Thu Jan 18 2018

Synopsis...showers will persist across the region through Friday.
These showers combined with cold air aloft will yield mountain
snow and possibly coastal hail. A brief period of drier weather
is expected to occur during Saturday, followed by another round of
rain on Sunday.

&&

Discussion...showers and a few thunderstorms are moving onshore
this afternoon. Snow levels are currently around 4,000 feet.
These are expected to become more vigorous tonight when the colder
air aloft moves overhead tonight in Friday morning. Instability
is not very impressive, but mid level lapse rates are over 8c/km
and h500 mb temps are around -34c north of Cape Mendocino. This
should bring fairly widespread small hail starting this evening.
This is starting in Crescent City first and spreading south
through the night and into Friday morning. Snow levels tonight are
expected to drop to around 2,000 to 2,500 feet tonight. Snow
accumulations of 3 to 6 inches are possible above 3,000 feet.
Locally higher amounts possible in the heavier showers.

Friday afternoon showers will diminish, especially over the inland
areas. They may linger a bit longer than currently expected as
the flow remains onshore. Saturday any lingering showers should
taper off as a brief period of high pressure builds into the
region. This is fairly weak so skies may not clear out very much.

Sunday the next cold front moves into the region. Models are
struggling with the strength of this system. The 12z GFS pushes the
main energy farther south and keeps area north of Cape Mendocino
much drier. The 12z European model (ecmwf) is similar to previous runs and much
wetter. Both models show the potential for low elevation snow in
Trinity with higher levels closer to the coast. The cold air in
place from Saturday night combined with some upslope flow on
Sunday may keep them around 2,000 or 2,500 feet for this event.

Monday showers look to end quickly as both models push the systems
out of the area. Tuesday the next system is expected to bring rain
and snow to the area. Some of the models are showing an extended
period of wet weather as the boundary stalls over US on Tuesday
through early Wednesday. Late Wednesday the upper level trough
moves over the area and snow levels will fall as the cold air
moves in and showers prevail. Mkk

&&

Aviation...rain and convective Post frontal weather disturbances
(shortwaves) will continue to rotate into northwestern California through
Friday as the associated upper level trough swings over the
region. By late Friday afternoon, shower activity should start
tapering. The cec, acv and uki air terminals can expect
fluctuating VFR-IFR conditions through the period...and especially
through this evening. Acv and cec terminals can particularly
expect multiple flight hazards including:
lower cigs/vis, mod-heavy shra, occasional tsrags (small hail),
lightning and convective wind gust.

&&

Marine...the very large westerly swell peaked around 4am this
morning with most buoys reporting significant wave heights of 28
feet around 18 seconds. This afternoon the swell is still being
measured at 19-24 feet around 17 seconds at our coastal buoys.
This swell will continue to very gradually decay over the next few
days. Southerly winds have also continued to decrease this
afternoon. This very large swell has also created very hazardous
conditions for traversing the Humboldt Bay entrance. Due to these
hazardous conditions the uscg has closed the entrances to
Humboldt Bay, as well as Crescent City and Noyo harbors at 1pm.
These entrances will remain closed until conditions improve. Winds
are still southerly at most locations however, they should begin
to turn more westerly and eventually northwesterly as we go
through the evening and Friday.

Sunday, winds and seas will yet again increase as another system
passes off to our north. Near gale to gale force winds will be
possible by Sunday morning and persist through early Monday morning.
These strong winds will also cause short period waves to increase on
Sunday. In addition to the short period waves, another large
westerly swell will begin to build across the waters beginning
Sunday morning. Conditions will gradually improve on Monday however
the sea state will remain elevated through early next week. /Wci

&&

High surf...a significant westerly swell is currently impacting
our area and will gradually begin to diminish late tonight through
tomorrow. Buoys just offshore today have been reporting waves of
22 to 28 feet which have resulted in high surf conditions along
all west and northwest facing beaches. A high surf warning remains
in effect through 10 PM this evening. /Wci

&&

Eka watches/warnings/advisories...
California...high surf warning until 10 PM PST this evening for caz101-103-
104-109.

Winter Weather Advisory from 7 PM this evening to 7 PM PST
Friday for caz105>108.

Winter Weather Advisory until 7 PM PST Friday for caz102.

Northwest California coastal waters...
California...high surf warning until 10 PM PST this evening for caz101-103-
104-109.

Winter Weather Advisory from 7 PM this evening to 7 PM PST
Friday for caz105>108.

Winter Weather Advisory until 7 PM PST Friday for caz102.

Northwest California coastal waters...
hazardous seas warning until 10 am PST Saturday
for pzz450-455-470-475.



&&

$$

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