Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 261121
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
421 AM PDT Tue Sep 26 2017

.SYNOPSIS...Above normal temperatures and dry conditions will
persist through Thursday with strong offshore winds through
Wednesday morning. Potential for rain showers near Oregon border on
Friday. Another rain chance early next week.


&&

.DISCUSSION...We will have a few more days of dry and warm
conditions. The upper level ridge will still be the dominant weather
feature along the West Coast through Wednesday night. Wednesday will
be the warmest day, with highs around 90 degrees for interior
locations. There will be slight cooling starting on Thursday as
cooler maritime air starts to filter into the region as we start to
feel the influence of the next upper level trough.

On Friday, models are hinting on a weak front passing through the
area. There will be potential for precipitation, primarily over Del
Norte County. Rainfall amount will be fairly light, at around one
tenth of an inch. Further south in Mendocino County, this front is
unlikely to bring in precipitation. Highs on Friday will be near
normal, around 80 degrees inland, 60s along the coast.

For the weekend, looks to be mostly dry. High pressure will build
into the area behind the front. After the weekend, looks like we are
heading into a slightly wetter pattern. A zonal flow will set up
over NW California, with occasional weather frontal passages and
resultant precipitation.

Forecast confidence is below average starting on Friday, as models
start to struggle about the transition into a wetter pattern.


&&

.AVIATION...High pressure continues bring mainly clear skies and
dry conditions to the area this morning. There is only a very
small area of of stratus in the Eel River Valley. Offshore flow
is expected to keep it this way across most of the area this
morning. The stratus in the Eel river valley may continue to
expand a bit more this morning, but it is not expected to make it
to KACV. This afternoon breezy winds are expected along the
coast, but they are expected to be lighter than yesterday. Tonight
some localized stratus is possible again, but models are
indicating offshore flow will continue so it is not expected to be
very widespread. MKK

&&

.MARINE...High pressure over the area will bring one more day of
moderate northerly winds. It looks like the strongest winds and
seas will remain offshore so am not planning to issue small craft
advisories for the inner waters today. Tonight into Wednesday
morning models are in decent agreement on winds becoming fairly
light across the waters. These light winds will continue on
Thursday and into Friday morning. There is still some disagreement
on the direction, but there will likely be some southerly winds
for a period of time.

Models are still in decent agreement on high pressure building
back into the area Friday night into Saturday and bringing a
return to moderate northerly winds. After this models start to
diverge. The GFS shows an inside slider type system moving down
from the north. This brings near gale to gale force northerly
winds to the waters. The ECMWF has a much different solution to
this system bringing it onshore as an upper level trough. This
brings light to moderate southerly winds and rain to the area.
This is the first run with these southerly winds. Confidence is
low on a particular solution so have kept it mainly in line with
the GFS, but with slightly weaker winds. MKK

&&

.FIRE WEATHER...Red flag warning remains in effect for Mendocino
and Lake counties through early Wednesday morning due to low
relative humidity and gusty winds. Models continue to show that
there will be periods of gusty NE winds, 20 mph sustained with gusts
to 30 mph, over Mendocino and Lake counties. Strongest winds will be
over ridge top levels, as suggested by the strong 925 mb to 850 mb
level winds. As of early Tuesday morning, RH recoveries were to
around 30 to 40 percent. Do expect the diurnal heating will drop the
RH to 15 to 25 percent this afternoon. Do expect the combination of
low RH and gusty winds will produce critical fire weather conditions
for at least 8 hours for those areas. Thus, keep the Red Flag
Warning as is. The gusty winds should subside starting on Wednesday.
Dry conditions will still persist through Thursday. There will be
increasing moisture starting on Friday, as the area starts to feel
the effect of more onshore flow. Dry conditions will return for the
weekend.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...Red Flag Warning until 8 AM PDT Wednesday for CAZ276-277.

NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 9 AM PDT Wednesday for PZZ470-475.

&&

$$

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