Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 252217

National Weather Service Eureka CA
317 PM PDT Sat Mar 25 2017

.SYNOPSIS...The next storm system will arrive sunday morning and
afternoon with widespread rainfall, higher elevation snowfall,
and gusty winds to locations along and west of the coastal range.
The on again off again showery pattern will persist through
Thursday morning, before dry weather returns for the remainder of
the week.


.DISCUSSION...The next storm system currently resides off the
north coast however some high clouds in its advance are now moving
over the region. This fairly strong area of low pressure will be
undergoing an occlusion process as it treks across the southeastern
Pacific sending a trailing cold front eastward. Ahead of this
front, a 925mb jet of 45 to 50 knots will develop across the outer
waters and along the Redwood Coast from Cape Mendocino north, in
the late Sunday morning into the afternoon time frame. This could
bring some gusty winds to locations to portions of Humboldt and
Del Norte counties. However, winds look to be slightly less than
yesterdays system. As the front crosses the region during the
afternoon and evening hours, widespread rainfall will spread from
west to east. Overall, rainfall amounts don`t look to be too
significant, but some locally heavy rainfall is expected, mainly
for portions of Humboldt and Del Norte County along the south and
west facing slopes. Things will be on a downward trend for Monday,
as precipitation becomes more showery. Some higher elevation
snowfall will occur during this time as well, with snow levels
gradually dropping from ~4500 to 3500 feet. Amounts will be light
enough though to preclude any real impacts to area passes, with
the exception being Scott Mountain Pass, where some light
accumulations will occur. As for the convective potential,
although 700mb and 500mb lifted indices do go slightly negative,
modest mid-level lapse rates and negligible MUCAPEs preclude any
thunder inclusion in the zones (forecast) at this time. Another
brief period of transient riding will build across the region
Monday evening into early Tuesday morning, with more dry weather
expected. However, another weak disturbance in the flow aloft may
bring additional precipitation back into the area for Tuesday
afternoon into Thursday morning time frame. this will need to be
watched though, as the models have shown a slight northward drift
in precipitation with some delay also seen in timing. In any
event, after this latter system, high pressure looks to build
across the state with perhaps a prolonged period, featuring mainly
clear skies and dry conditions. /PD/JT


.AVIATION...VFR conditions across all terminals this afternoon. Do
expect the VFR conditions to persist through first part of tonight.
Rain will be spreading into the area by early tomorrow morning.
Flight categories will be lowering by early morning as more steady
precipitation moves into the area lowering visibilities and ceilings
across all terminasl. Winds will be gusty tomorrow morning, with
wind shear a possibility for Crescent City and Arcata airports
starting early tommorw morning. /RCL


.MARINE...Fairly active pattern for the marine forecast.
Moderately steep seas and light winds for tonight. Winds will pick
up to advisories and warning level tomorrow morning. Light winds
and moderately steep seas will resume tomorrow night. A fresh
swell will be moving into the area starting on Monday night.

Winds have been fairly light today, with wind speed generally less
than 10 kt. However, waves are moderately steep. Buoys have been
reporting combined seas of 9 to 11 feet at around 9 to 10 seconds.
Do expect the elevated seas to continue through tonight. Thus, issue
a small craft advisory to account for the elevated seas.

The weather front will push towards NW California coast through
tonight. Winds will become south and increase overnight. Winds will
reach gale warning criteria for the northern outside water, while
reaching small craft advisory criteria for the rest of the waters.
This weather front will push through and weaken during the day, the
wind should collapse by the evening. After that, the wind regime
should shift to north and northwest for the rest of the forecast

With a northwest flow, we will have a fresh northwesterly swell
approaching NW California coast by Monday afternoon. The swell will
then remain in the area through the work week.

Changes to the previous forecast package is fairly minor. Used
ECMWF/GFS in refreshing the forecast package.


NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 3 PM PDT Sunday for PZZ450-455-475.

     Small Craft Advisory until 9 AM PDT Sunday for PZZ470.

     Gale Warning from 9 AM to 3 PM PDT Sunday for PZZ470.



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