Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 172259

National Weather Service Eureka CA
259 PM PST Sun Dec 17 2017

.SYNOPSIS...High pressure will maintain dry weather through
Monday. A cold front will bring a chance for rain Tuesday and
Wednesday followed by another long stretch of dry weather.


.DISCUSSION...Dry weather conditions will persist Monday through
Tuesday morning as high pressure shifts over the Pacific Northwest.
Some high level clouds will spill over the ridge from time to
time. Also, patchy low cloud and fog may form during the night
and morning hours along the north coast and in some of the
interior river valleys.

A cold front will approach from the NW Tuesday afternoon bringing
rain to mainly Del Norte county by mid to late afternoon. The
bulk of rain for the rest of the area will most likely arrive late
Tuesday afternoon into the evening hours. Rain amounts will be
modest with the highest amounts expected in Del Norte county. The
rain will quickly change over the showers after frontal passage
Tuesday night. The models were still not in fabulous agreement
with the timing, but Tuesday evening from 4pm to 10pm looks to be
the best chance of rain for the northern zones and after 10pm for
the southern zones.

Snow levels will fall behind the front late Tuesday night and
some snow showers will be possible for the higher terrain through
mid day Wednesday. Overall, the precipitation amounts are not
looking sufficient to warrant an advisory. The best chances for
snow will be Wednesday morning above 2000 to 2500 feet. Snow
showers may impact travel over the mountain passes, so we hoisted
a weather story graphic to call attention to this road hazard.
Also, there will be a threat for low top convection and small hail
Wednesday morning as freezing levels fall to 2kft or less. Small
hail has been added to the forecast as well.

Beyond that, the GFS, ECMWF and GEM indicate another shortwave
diving southward Friday night. This front is looking dry and no
rain is expected at this time. This front will user in much colder
air (modified arctic for NW CA) and increase the potential for
blustery easterly and northeast winds, primarily for the upper
elevations next weekend. It will be the coldest air of the season
so far, though it is December and not too unusual.

The models continue to indicate westerly flow breaking through
and undercutting the large scale block early next week. This is
most likely overdone or too fast. December is usually the wettest
month of the season, however this December will likely go down as
one of the driest on record.


.AVIATION...Quiet conditions will continue for the TAF cycle as
high pressure holds over the region. Coastal terminals and
associated river valleys may see areas of patchy fog develop
tonight but conditions are not expected to fall below MVFR.
Current TAF package keeps VFR conditions in place overnight but
brief periods of MVFR conditions may occur if the fog develops.


.MARINE...High pressure will continue to build over the Pacific
resulting in decreasing northerly winds today resulting and the
sea state slowly subsiding subside. Lighter winds are expected for
Monday and will last through Tuesday before a frontal system
moves through the region. This will increase winds and shift them
to the south. A northwesterly swell will remain the dominant
feature through this period.


Small Craft Advisory until 10 PM PST this evening for PZZ475.



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