Area Forecast Discussion
Issued by NWS Eureka, CA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

FXUS66 KEKA 132221

National Weather Service Eureka CA
221 PM PST Thu Dec 13 2018

.SYNOPSIS...A cold front will bring a quick shot of rain, gusty
winds, and modest mountain snows on Friday. Another cold front
will sweep through the area on Sunday.


.DISCUSSION...Skies were mostly sunny across the area today. High
clouds are forecast to gradually thicken and lower overnight
tonight ahead of an approaching frontal system. In addition, SE to
S winds will begin to increase late this evening. As a result of
the increasing clouds and downslope winds, forecast low
temperatures along the Redwood Coast are presently in the mid 40s.
However, it appears there will be some favorable radiational
cooling conditions after sunset, so temperatures could drop a few
degrees lower than forecast before rising again later in the

Wind speeds/gusts are expected to increase to just above advisory
criteria over portions of the N half of our area, specifically the
Del Norte coast and interior elevations above 1500 ft. A Wind
Advisory was hoisted by the midnight shift, and, other than a
slight extension to the expiration time, this remains unchanged.
This storm system will be progressive, with rainfall totals
expected to range from near one inch in the N mountains to just
over a quarter of an inch over the extreme southern coastal areas.
Coastal downsloping is expected to limit rainfall amounts a bit
along the coast, particularly along the Redwood Coast. This will
also likely delay the start time of the significant precipitation
in those area. Snow amounts in the highest elevations of N Trinity
County will likely approach 6 inches, but this should be away
from major thoroughfares.

Saturday is expected to be a drier day, although some showers may
linger around the southern interior areas. Another fast-moving
storm system will transit the area on Sunday. Integrated moisture
transport (IVT) with this system is more impressive, but, again,
the progressive nature should keep localized flooding potential
low. There is the potential for a bit more convective
precipitation with this storm, so will need to evaluate the
potential for burn scar issues as we get closer to the event.

Another storm system may affect the area on Tuesday of next week,
but indications are that this feature will mainly affect the
Pacific NW, with the best chances of rain in our area over the N
zones. Temperatures will be near to slightly above normal through
the period. /SEC


.AVIATION...Mainly clear skies have been prevailing across the
region today. VFR conditions are expected to continue tonight as a
frontal system approaches, however increasing south-southeast winds
aloft ahead of the front may result in low level wind shear toward
early Friday morning. MVFR and brief IFR conditions will be possible
through the day on Friday as rain develops right behind the front.


.MARINE...An active weather pattern across the north Pacific
will continue to result hazardous ocean conditions through early
next week. A mid-period westerly swell will slowly subside tonight,
however another mid period swell group will build on Friday. Seas
are forecast to reach warning criteria on Friday. A frontal system
will move into the coastal waters late tonight, bringing gusty
southerly winds by Friday morning. Gale warnings are in effect for
the northern waters where winds are expected to peak around 40 kt
around sunrise or shortly thereafter on Friday. Winds should die
down by Friday night. A second storm system will approach on
Saturday, resulting in another round of gale force winds on Sunday.
This second storm has also been generating large westerly swell that
will spread into the waters on Sunday. This long period swell will
combine forces with steep southerly wind waves on Sunday, resulting
in seas around 25 feet or so. Winds should quite down some on
Monday, however seas will likely remain quite elevated and perhaps
still around 20 ft or so.

BEACH HAZARDS...A mid period westerly swell may result in breaking
waves around 20 ft north of Cape Mendocino on Friday. A much more
significant westerly swell is expected to build Sunday into Monday.
This long period west swell will build to 20+ feet, which may result
in breakers over 30 feet. A High Surf Advisory or Warning will be
issued as we near the event. We have hoisted a weather story graphic
to call attention to this beach hazard. People planning any beach
activities should exercise caution and stay farther back from the
surf and off of jetties. Beach conditions will remain unsafe and
hazardous through at the early portion of next week.


CA...Wind Advisory from 3 AM to 11 AM Friday for CAZ101-102-104>106.

     Small Craft Advisory until 4 AM Friday for PZZ450.
     Gale Warning from 4 AM to 3 PM Friday for PZZ450.
     Small Craft Advisory until 9 PM this evening for PZZ470.
     Gale Warning from 9 PM this evening to 3 PM Friday for PZZ470.
     Small Craft Advisory until 2 PM Saturday for PZZ455-475.


Visit us at

Follow us on Facebook and Twitter at:

For forecast zone information
see the forecast zone map online: is the U.S. government's official web portal to all federal, state and local government web resources and services.