Area forecast discussion
National Weather Service Eureka California
331 PM PDT Sat may 25 2013
Synopsis...a weak system will bring light rain to areas north of
Cape Mendocino tonight into Sunday morning. More widespread and
heavier rainfall is expected Sunday night through Monday as a
stronger storm system moves through the region.
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Discussion...mostly clear skies across the region developed today
in association with subsidence in an upper level ridge ahead of an
advancing shortwave trough. This trough will bring light rain to
the northern half of the County Warning Area beginning this evening through the
morning hours. Rainfall will range from a trace in coastal
southern Humboldt County to over a quarter inch in del Norte
County.
This shortwave will move east of the area during the day Sunday with
weak upper level ridging building over northwest California for
Sunday afternoon and evening. This should allow some of the lower
clouds to dissipate leaving middle and high clouds spreading over the
area ahead of the next much stronger system. Divergent flow aloft
will spread over northwest California in the evening at the same
time as weak warm air advection begins to develop. This should allow
light rain to spread over areas north of Cape Mendocino by around
midnight. A strong upper level jet and shortwave will begin to
influence the region early Monday morning enhancing the rainfall and
expanding the rain over all of northwest California. Models have
trended toward heavier rainfall then was predicted in previous
runs...so have increased the quantitative precipitation forecast forecast for the region in line
with the rfc. The heaviest rainfall will likely occur north of Cape
Mendocino in the mountains of Humboldt and del norte counties
during Monday morning. A cold front will push inland during the
day Monday with rainfall decreasing through the evening. Rainfall
totals will range from 0.15 inches in far southern interior
Mendocino County to over an inch in del Norte County. Snow levels
will remain above 6000 feet.
Cold air advection and ridging will redevelop over the region on
Tuesday bringing a brief period of drier conditions...however with
onshore flow still anticipated have kept chance probability of precipitation in the
forecast. A final shortwave will move through Tuesday night into
Wednesday morning bringing a last shot of rainfall to the region
before a large upper level ridge builds back over the West Coast
for the remainder of the week. Rpa
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Aviation...VFR conditions, partly cloudy skies and light to moderate
winds will continue at kcec and kacv through the early evening.
Cloudiness will increase, showers will move through the area at
times and patchy fog will occur overnight and early Sunday morning
at kcec and kacv reducing ceilings and visibilities to MVFR and
temporary IFR conditions. VFR conditions will continue at kuki
through Sunday.
&&
Marine...light to moderate winds and moderate seas will prevail
across the waters through the middle of next week. The winds and
seas will increase Wednesday night and Thursday as a weak cold front
moves through the region and a high pressure system strengthens
behind the front increasing the pressure gradient.
&&
Eka watches/warnings/advisories...
California...none.
Northwest California coastal waters...none.
&&
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