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Area forecast discussion 
National Weather Service Eureka California
345 PM PDT Thursday Aug 28 2014

Synopsis...clear conditions will persist across interior northwest
California tonight while low clouds and fog reassert themselves
along the coast. An upper trough approaching from the northwest will
bring a cooling trend to the area through Saturday. Another
warming trend will occur during the first half of next week.


Discussion...afternoon water vapor imagery shows a stretching
small upper low over northwest California. This caused some high clouds
today, but that's about it. The upper ridge to the south is
attempting to reassert its dominance by nosing back northward, but
a large upper trough over the Gulf of Alaska is battling for the
same position. Models continue to show the upper trough winning
out through the first half of the week. However, this ridge will
not leave quietly. Expect another night of low clouds and fog
along the coast with areas of drizzle. Fog is expected to be
locally dense again as the upper and surface ridges suppress the
marine layer down to the lowest few hundred feet. By Friday the
trough will begin to sweep through which will cause a deepening
marine layer through Friday night. This may allow for deeper
penetration of coastal fog and stratus to the interior.
Otherwise, this trough is not expected to do much more than bring
a slight cool down to the interior. Models are in decent agreement
that another ridge will transit into the region by early next week
which will bring a warming and drying trend for a few days before
another upper trough slips into the area. At this time there
appears to be no organized systems which would bring US any threat
of thunderstorms. The most the mountains will have to deal with
are gusty Ridgeline winds as this trough passes. Forecast-wise
continued with the ongoing forecast as things seem to be on track.
The most significant change was overnight tonight to add drizzle
along the Redwood coast under a tightly bound marine layer. Bfg


Aviation...coastal airfield conditions today were very similar to
yesterday with much of the coast inundated with stratus and
intermittent clearing in the afternoon. Stratus will return to any
scattered areas by early this evening. Expect low ceilings and
visibilities (ifr to lifr) to return again tonight as ridging
maintains a stronger marine inversion. Southwesterly flow aloft
allowed smoke from fires in Siskiyou to drift out of the area
today. VFR will prevail across the interior with high pressure in
place. However some airfields near Siskiyou fires may see some
smoke overnight as winds aloft weaken and turn north to NE. Rpa\kml


Marine...northerly winds will increase overnight through Friday
afternoon as the ridge offshore and the thermal trough over
California interact and strengthen the coastal pressure gradient.
The 20z ascat pass showed light winds offshore so the advisories
were postponed until 10 PM tonight. The strongest winds and
highest seas should remain offshore, however, steep seas may
propagate into the inner waters. A brief decrease in northerly
winds may occur on Saturday across the northern waters yet winds
are expected to remain higher south of Cape Mendocino. By early
next week, strong ridging off the West Coast will bring near gale
conditions across the coastal waters through the middle of next

Southerly swell continues to move through the waters originating
from now downgraded Tropical Storm Marie. This swell will subside
through Friday decreasing the threat of stronger currents. Rpa\kml


Eka watches/warnings/advisories...
Northwest California coastal waters...Small Craft Advisory from 10 PM this evening to 3 am PDT
Saturday pzz470-475.



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