Weather Service Report


855 
FXUS66 KEKA 271145
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
445 AM PDT Tue Jun 27 2017

.SYNOPSIS...A few thunderstorms are possible over the Trinity horn
late this afternoon and this evening. After that, the weather will
return to a more typical summer pattern of mostly dry conditions.
Warm temperatures will return to inland areas by Wednesday and 
persist through the weekend. Marine stratus will continue along 
the coast during the overnight hours through rest of this week.

&&

.SHORT TERM (today thru Thursday night)...Low clouds, along with
some patches of drizzle, continue to cover much of the coastal 
waters and adjacent land areas. The marine layer is deep (at least
2000 feet deep). As a result, there are minimal visibility 
reductions, but the clouds themselves have pushed well inland into
the higher elevations. The latest profiler info from ACV 
indicates that the marine layer likely maxed out in depth several 
hours ago and will decrease in depth as we go through the day. As 
a result, the high resolution models are indicating more erosion 
of coastal clouds through the day, with partly cloudy skies 
possible during the afternoon even near the coast. However, models
also indicate a seabreeze developing, which would act to push 
remaining coastal clouds back toward the coast later in the day. 
Nighttime and morning coastal clouds will continue over the next 
few days, but improvement should be noted by each afternoon.

Convection Monday afternoon fired well NE of the Trinity Horn 
while convective inhibition (CIN) limited development closer to 
the area. Models continue to indicate a vorticity maximum moving 
from NW to SE toward the area this afternoon and evening on the 
backside of a departing and filling trough. It still appears there
will be enough instability over W Siskiyou County to support at 
least isolated thunderstorms, and storm motion should carry them 
SE into E Trinity County. Have continued to include this in the 
forecast. The timing for this activity appears to be either very 
late this afternoon or early this evening.

Inland temperatures will be near normal today, then rise to about
10 degrees above normal by Wednesday as an upper ridge builds 
back over the area. Present indications are that little in the way
of offshore flow will develop, which will keep coastal areas 
seasonable. The weather will be mostly dry. /SEC

.LONG TERM (Friday thru Monday)...The longwave pattern holds 
ridging over the western United States Friday and Saturday before a 
broad trough shifts over the west on Sunday into early next week. 
Thus expect mostly dry weather this weekend with inland temperatures 
continuing to reach above normal values for this time of year. 500 
mb heights will fall Friday and Saturday as a shortwave embedded in 
the upper flow approaches the region from the northwest. Some 
convective showers, possibly a thunderstorm, may be possible across 
the interior Friday afternoon/evening as this shortwave slides over 
the region. However, summertime thunderstorms tend to be more 
conducive when shortwaves travel from the southwest, with 
southeasterly winds helping to prime the environment for storm 
development with moisture and instability. All in all, still not 
confident enough to add storms to the forecast at this point in 
time. Coastal temperatures will remain more seasonal with stratus 
likely impacting parts of the northwest coast with scattering 
afternoon skies. /KML.

&&

.AVIATION...The stratus deck early this morning wasn't as expansive 
as previous mornings with patchy cloud coverage along the NWCA 
coast. The marine layer, however, remained deep as satellite imagery 
showed stratus penetrated well inland once again last night. MVFR 
ceilings this morning are expected to lift and scatter resulting in 
predominately VFR conditions along the coast by the afternoon. MVFR 
ceilings should return to the coast tonight with VFR expected to 
prevail across most of the interior. /KML

&&

.MARINE...Surface high pressure has begun to build back towards 
the California coastline. This tighter pressure gradient is 
beginning to increase the northerly winds across the waters which 
will in turn increase wave steepness later this afternoon. 

A small craft advisory is currently set to take effect Tuesday 
evening for the outer waters. This will have to be watched carefully 
by the day shift as latest model trends have come in faster with the 
small craft advisory winds. If observations show this speedier 
solution the small craft advisory may go into effect this afternoon. 
Some gale force gusts will be possible across the outer waters 
starting Wednesday afternoon however with limited spatial coverage 
and marginal strength no gale warning will be required (yet?).    

The inner waters small craft advisory will take effect very early 
Wednesday morning with the primary concern of large steep waves. 
Winds should stay below small craft advisory except near Cape 
Mendocino and Point St George where gustier winds are expected. 

While the small craft advisories only go through early Friday 
morning these may need to be extended.  For now will hold of on 
extending the advisories until we get later into the week.  The 
outer waters small craft advisory may need to get upgraded to a gale 
warning Friday evening  as the southern outer waters could 
experience some more widespread gale force gusts through the 
weekend. The northern outer waters may also need a gale warning for 
late in the weekend as well, as gale force gusts should increase in 
spatial coverage.  Stay tuned for possible extensions or upgrades. 
/WCI

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory from 3 AM Wednesday to 3 AM Friday for 
     PZZ450-455.
     Small Craft Advisory from 9 PM this evening to 3 AM Friday 
     for PZZ470-475.

$$

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Western Regional Climate Center, wrcc@dri.edu