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Area forecast discussion 
National Weather Service Eureka California
410 PM PDT Wednesday Sep 17 2014

Synopsis...isolated thunderstorms along the Humboldt and del
norte coast will continue through this evening then taper to
showers. Showers and thunderstorms are expected to develop
overnight into Thursday morning across the Mendocino coast as a
vigorous system moves ashore. This same system will bring showers
and thunderstorm to interior regions of Mendocino and southern
Trinity counties Thursday afternoon.


Short term (tonight through thu)...low pressure off the coast of
northwest cal will slowly push through the region through Thursday. This
low is bringing periods of heavy rain showers along with isolated
thunderstorms. The majority of the thunderstorms this evening will
be offshore with a few limping across coastal regions. Models are
in good agreement as the low transits the area with a vorticity maximum
sweeping around its south side bringing a bulls eye of precipitation to
coastal Mendocino Thursday morning. This vorticity maximum may prove to be
vigorous enough to produce isolated thunderstorms in the early
morning hours. As the low moves inland it will take its
instability to the east and potentially trigger off the mountains
of Mendocino National Forest. Models have only begun to pick up on
this solution and will need to be watched closely overnight for
development. To the north...del norte and Humboldt will see the
vast majority of the convection this evening then should taper to
showers overnight with limited convection.

Fire weather concerns remain with this pattern, especially across
the interior, due to lightning, dry fuels, and forecasted limited
amounts of rain for the interior.

Long term (fri through wed)...high pressure will build in over
northwest California on Friday as the upper trough slides off to the
south and east...transitioning into a cut off low that then dives
south...settling over Southern California...and moving off to the
east by Monday. Models are in good agreement with this solution. Dry
conditions along with light offshore flow and above normal
temperatures will return to northwest California and dominate the
weather pattern into early next week as heights build. A southerly
coastal stratus surge looks possible Saturday night into Sunday with
a flow reversal over the waters. The light offshore flow will likely
give coastal locations above normal temperatures with the warmest
day looking like Saturday.

By late Tuesday into Wednesday models forecast another upper level
trough to approach northwest California. Have increased probability of precipitation to
slight chance/chance across the northern half of the County Warning Area and this
matches up well with the neighbors. Rmop tool shows low
predictability in the pattern for this time period. This is still
aways out and there remains quite a bit of uncertainty. Will monitor
the situation. Stp


Aviation...MVFR to LIFR conditions and light winds will continue
at kcec and kacv through Thursday morning as showers move across
the area reducing ceilings and visibilities at times. Temporary
LIFR conditions will occur at times at kcec and kacv overnight and
early Thursday morning due to reducec visibilities and ceilings.
VFR conditions and light winds will prevail at kuki this
afternoon. However MVFR to IFR conditions will occur overnight and
early Thursday morning due to reduced ceilings and/or


Marine...a low pressure system moving across the region has
increased the seas across the waters primarily across the outer
waters. Seas will remain elevated tonight then subside slightly
Thursday and Friday. A high pressure system will strengthen offshore
Friday increasing the winds and seas. Winds and seas will be higher
across the outer waters Friday. The winds and seas will diminish
this weekend and early next week as the high pressure system weakens
and a low pressure trough prpagates eastward north of the area.


Eka watches/warnings/advisories...
Northwest California coastal waters...none.


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