Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 252301
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
401 PM PDT THU AUG 25 2016

.SYNOPSIS...Warm and dry conditions will continue throughout the
interior, while cool, cloudy and foggy conditions will persist
along the coast. A cooling trend is expected late in the weekend
and early next week.

&&

.DISCUSSION...Typical summertime conditions persist across
northwest California today, with stubborn shallow fog and stratus
across much of the waters and immediate coast, and warm, dry
conditions across the interior. While there was some afternoon
erosion of clouds/fog along the immediate coast this afternoon,
stratus coverage actually spread farther north and expanded across
the waters through the day despite drying aloft. At this point,
it appears that this stratus is here to stay through at least
early next week, and will likely continue to expand in coverage as
southerly flow increases and spreads across the majority of the
waters in the next 24 hours. In fact, while the marine layer will
remain somewhat shallow, this increased southerly flow may aid the
formation of overnight and morning drizzle in some areas as well,
particularly from Cape Mendocino southwards where coastal
mountains will be more favorably oriented for orographic
enhancement.

Over the next two days, the weak upper trough currently situated
over the area will give way to a modest ridge and zonal flow, and
by mid-week a series of stronger upper troughs will pass through
the area. Expect a continuation of warm and dry conditions across
the interior, with a very slight cooling trend that becomes more
pronounced by mid week. Stratus and fog will continue along the
coast through at least early next week, with more uncertainty
towards the middle of the week as upper troughs impact the region.
By late week, a deeper storm system may even bring some light rain
to the region, and while uncertainty remains high, slight chances
for showers have been introduced for northern portions of the
area beginning Thursday. /BRC

&&

.AVIATION...This morning, there were some very dense fog in part
of the coastal area. Visibilities in Arcata was less than one
quarter of a mile at times. As the day goes on, the coastal fog is
slowly burning off. Visibilities has improved to 5 miles or better
in Crescent City and Arcata airports. However, there is still a
low overcast deck at around 300 feet in both locations. Do expect
IFR/LIFR conditions to persist through the afternoon. By early
evening, the marine stratus will make its nightly intrusion back
to the area. Do expect Eureka and Arcata to be back in LIFR. The
marine stratus will attempt to break again during the daytime on
Friday. For Ukiah, expect VFR conditions to persist. /RCL

&&

.MARINE...No marine hazards for the next few days...aside from
persistent fog which may become dense at times. As of early this
afternoon, buoys offshore are showing generally 4 foot waves with
wave period of around 8 seconds. The winds at these buoys are also
fairly light, to around 10 kt. The low seas and light and variable
winds conditions will continue overnight. Winds will shift to the
south overnight. Along the coast near Cape Mendocino, there will
be some healthy southerlies developing during the day on Friday,
with 10 to 20 kt sustained and up to 30 kt gusts. The southerlies
will relax Friday night into Saturday. Models are hinting on the
light and variable winds will continue into Sunday. By early next
week, looks like the northerlies will return to the area once
again. However, models are starting to diverge by early next week.

There are several wave groups. The short period wave will be coming
in from the northwest. There are two long period wave groups. One
will be coming in from the south, and another one coming in from the
southwest. But overall, the waves should be below advisory criteria.

Minor changes were made to refresh the forecast package. Forecast
confidence is near average. Models of choice is GFS. /RCL

&&

.FIRE WEATHER...Overnight RH recoveries are expected to be
moderate to poor along upper slopes and even some higher mid
slopes across much of northwestern CA tonight and tomorrow
morning. While winds are expected to be generally light in most
areas, some gusty easterly winds are expected to develop across
the typical areas of Del Norte and northern Humboldt counties.
This will primarily affect exposed high elevations, while valley
bottoms will continue to remain mostly sheltered with light winds
and good RH recoveries. Conditions tomorrow afternoon will once
again feature warm afternoon temperatures and low minimum
humidities, although some improvement will be possible as a surge
in southerly winds may bring a temperatures down a few degrees
across low lying areas of Mendocino county.

Heading into the weekend and early next week, an approaching
trough of low pressure will result in a gradual cooldown and
modest increase in humidity. Winds are expected to remain
generally light and terrain driven. Thunderstorm chances are
minimal through at least early next week.

&&

.EKA Watches/Warnings/Advisories...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...None.
&&

$$

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