Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 181126

National Weather Service Eureka CA
326 AM PST Mon Dec 18 2017

.SYNOPSIS...High pressure will maintain dry weather through
Monday. A cold front will bring rain to most of NW CA Tuesday
and Wednesday followed by another long stretch of dry weather.


.DISCUSSION...Pleasant winter weather conditions continue through
Monday night as high pressure shifts over the Pacific Northwest.
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. 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 a
winter weather advisory...but some highway passes may see The
snow on the road surface early Wednesday morning above 2000 to
2500 feet. Thus snow showers may impact travel over the mountain
passes and a current weather story graphic calls 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...VFR high level clouds have expanded over Northwest
California and will continue to thicken and lower today through
Tuesday. The only ceilings of concern are some coastal stratus
that have formed north of Cape Mendocino. IFR or LIFR is expected
through mid morning at ACV and possibly expanding toward CEC.
There is some uncertainty as to how well these clouds will scatter
for the afternoon but most guidance shows VFR redeveloping for
the afternoon hours and tonight. /RPA


.MARINE...Surface high pressure will bring light winds and relatively
low seas through tonight. Winds will begin to increase out of the
south on Tuesday as a cold front approaches the waters. Strong to
near gale force wind gusts are forecast just in advance of the
frontal passage with seas building in response. Some gale force
gusts are anticipated in the northern waters for an hour or two
but they should be limited enough to not require a gale warning.
Small craft advisories will need to be issued later today for

Winds will turn out of the northwest and then north behind the front
allowing a northwesterly swell to build into the waters. Steep short
period seas developing from the moderate to strong north winds will
combine with this swell allowing small craft conditions to persist
through Wednesday and possibly into Thursday. Winds are expected to
relax late in the week and over the weekend as surface high pressure
builds back over the eastern Pacific. /RPA




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