Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 251339

National Weather Service Eureka CA
639 AM PDT TUE OCT 25 2016

.SYNOPSIS...Mainly dry conditions are expected today with a few
light showers possible. A warm front will bring light rain to the
area tonight. A frontal boundary will stall out over Humboldt and
Del Norte counties bringing rain Wednesday before moving through
the area on Thursday. Additional systems will bring periods of
rain into next week.


.Update...Did a quick update to the forecast to lower the pops
across much of the area for this morning. The shower coverage is
less than expected this morning. Light rain or drizzle is still
expected to start mid to late afternoon and quickly spread across
the area. Otherwise the forecast looks to be on track. MKK


.PREV DISCUSSION... /issued 450 AM PDT TUE OCT 25 2016/

DISCUSSION...This morning the water vapor shows a very active
pattern across the eastern Pacific. The next system to impact the
area is a robust shortwave moving around the base of the broad
upper level trough off the west coast. This will make today a
mainly dry, partly cloudy and breezy day for much of the area.
This shortwave develops a surface low that the GFS has dropping
994 mb well off the Oregon coast. This low moves by the area off
the coast keeping the strong winds well offshore, but we will
still see breezy south winds. Gusts to 40 mph are possible late
tonight and Wednesday morning along the coast and near coastal
ridges. Higher gusts are possible in which case a wind advisory
would be needed. First it will bring a warm front to the area.
Light rain or drizzle will start in the afternoon, first in
Mendocino county then quickly spreading north. Tonight rainfall
amounts will vary widely with over an inch possible in Humboldt
and Del Norte county. In Mendocino and Trinity counties rainfall
amounts will range from a few hundredths to a half inch.

Once the is warm front passes tuesday night the cold front will
be just off the coast. In Del Norte county there may not
be a break in the rain. Wednesday morning this front will move
onshore and stall out over Humboldt and Del Norte counties. Due to
the angle it is coming in at Mendocino county looks to stay mainly
dry. The models have come into better agreement that this front
will stall out in this position. The ECMWF trended toward the GFS,
although the NAM still keeps the front off the coast. So for now
have gone the GFS/ECMWF solution, however the NAM solution is
certainly still possible. Wednesday night the GFS and ECMWf are in
general agreement that the front will remain relatively stationary
over Humboldt and Del Norte County. The front finally starts to
move through on Thursday when another wave comes and kicks it into
motion. Rainfall amounts in Humboldt and Del Norte county will
range from 2 to 4 inches while less than an inch is expected in
most of Mendocino and Trinity counties. Trended the QPF forecast
towards the WPC QPF. Confidence is lower than average on this

Thursday night into Friday morning another wave from the
southwest brings rain to mainly Trinity and Mendocino counties.
Additional waves moving through the southwest flow and will
continue to bring periods of rain to the area through at least
early next week. The week ahead looks to continue to be very
active with small and fast moving systems. This means that a
slight shift in the trajectory would make a big difference in the
weather in a particular location. MKK

AVIATION...Light winds with mainly VFR Conditions will continue
at KCEC and KACV through the morning. Farther south at KUKI,
ceilings have been alternating between 400 feet ceilings and VFR
conditions. This is likely due to some radiational fog from the
moist soil conditions and calm winds. For now, will carry a TEMPO
group to cover this. Winds will increase overnight as the next
system draws near and rain approaches the region, with reduced
visibilities or ceilings likely at all TAF locations. /PD

MARINE...Seas have been on a downward trend this morning, after peaking in
the 16 to 19 feet range earlier. Wave periods have been rimming in
the 13 to 15 second range, which has occasionally touched the
hazardous seas criteria for our outer waters. However, given they
have only marginally reached this and a decrease in wave morphology
has already been observed, we`ll keep the current small craft
advisories as is.

The next storm system to affect the region will be approaching the
area by tonight. Winds will rapidly increase ahead of this system,
with seas building as well. The current gale watch in effect looks
good for the outer waters, and this will likely be upgraded to a
warning with the afternoon package. For the waters within 10
nautical miles, gale force winds will probably develop near Cape
Mendocino, but be confined to near that location, with the remainder
of the inner waters more of a forecast challenge, as they`ll likely
stay in small craft advisory criteria. This is something we`ll
continue to look at before deciding which way to go (small craft
versus gale warning) during the morning, with the eventual outcome
also included in the afternoon package. /PD


.EKA Watches/Warnings/Advisories...
NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 9 PM PDT Wednesday for PZZ450.

     Gale Watch from this evening through Wednesday morning for

     Small Craft Advisory until 8 PM PDT this evening for PZZ455-470-



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