Scientific Forecaster Discussion
fxus66 keka 221210
Area forecast discussion
National Weather Service Eureka California
410 am PST Mon Jan 22 2018
Synopsis...dry weather today, transitioning to wetter weather
late tomorrow. The next storm system will arrive tomorrow night
and continue to affect northwest California through Friday.
Discussion...a few showers are lingering on radar this morning
but will be short lived as a transitory high sets up over the area.
A broad trough situated over the Gulf of Alaska will sag towards
the Pacific northwest pushing a frontal boundary into our region
by late Tuesday morning. Winds will be increasing from the south
during this time frame which should warm coastal temperatures to
the upper 50s and low 60s. Right now winds are expected to be just
below Wind Advisory criteria but this could change as we get
closer to the event. Precipitation will gradually spread from the
northwest to the southeast with widespread rainfall across the
County Warning Area expected by Wednesday morning. Rainfall amounts are still a
bit questionable but most areas should see 1 to 3 inches of
accumulation with higher amounts possible in del Norte County and
favorable areas of orographic lift. Following the rain on
Wednesday, wet weather will continue into Thursday. The difference
with this next round of precipitation is that the atmosphere will
become much colder dropping snow levels down to 2000 to 2500 ft.
This means accumulating snow will be possible at pass levels and
that small hail is possible for coastal areas. Showery conditions
will then continue into Friday with the weather becoming more
uncertain for the weekend. Model guidance continues to bounce
around between dry and wet weather for the County Warning Area. Areas north of
Mendocino County have the best chances for staying wet through
Sunday morning with a brief period of dry weather expected for the
rest of the day.
Aviation...patchy ground fog will be possible across the region
this morning in the wake of sunday's rain. Otherwise, winds will be
variable during Monday, with clouds generally scattering out with
time. Fog development will be possible tonight once again,
particularly in the vicinity of kuki, where skies will be clearest.
Near the north coast, mid and upper clouds will be on the increase
late tonight in advance of another storm system.
Marine...a westerly swell will gradually subside during the next 24
hours, and winds will generally be light and variable. Southerly
winds will increase significantly during Tuesday as a frontal
boundary approaches from the northwest. Gale force winds are
expected over marine zone 470 Tuesday afternoon and evening, with
solid small craft speeds probable over the remainder of the coastal
waters. Winds will decrease slightly on Wednesday as the front exits
the region. However, seas will remain hazardous as a westerly swell
from 15-20 feet builds during Thursday.
Northwest California coastal waters...Small Craft Advisory until 4 am PST Wednesday for pzz450-455-475.
Gale watch from Tuesday morning through late Tuesday night for
Small Craft Advisory until 7 am PST Tuesday for pzz470.
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