Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Eureka California
315 am PDT Friday Mar 27 2015
Synopsis...a weakening front will generate a push of moisture
and perhaps some light showers tonight north of Mendocino County.
High pressure will rebuild Sat and sun for a return of dry
Discussion...stratus is now well entrenched along the coast with
some areas of dense fog bring reported. As a weakening front
approaches northwest California today the marine layer should deepen
allowing the ceilings to lift. With wind speeds expected to remain
fairly light most coastal areas will remain cloudy today. With the
deepening marine layer it would not be a surprise to see some
drizzle at times through the day today but widespread drizzle is
not currently anticipated.
By this afternoon/evening the weakening front will reach the coast
increasing lift. This front will likely have just enough forcing to
trigger some light showers/rain north of Cape Mendocino over a few
hour period primarily from around 3 PM to 9 PM. Total precipitation
is expected to remain mostly below a tenth of an inch in del Norte
County to around a trace to a few hundredths in Humboldt Bay.
Dry conditions will return on Saturday though there may be just
enough instability to allow a few showers to form over the higher
terrain of Trinity County Saturday afternoon as the front
dissipates/moves inland. With the front not being too strong the
marine boundary layer will likely not completely break
apart...thus resulting in continued cloudiness near the coast
through the weekend. Some increase in northerly winds will allow
for partial afternoon clearing each day.
Another system will move into the Pacific northwest Monday
evening/night with the tail end of the front impacting northwest
California. Models are in general agreement of some light rain
impacting areas north of Mendocino County so have increased chances
for precipitation during this time frame. Still...total rainfall
from this system is expected to be very light with only a 6 hour or
so window for precipitation.
Northwest California will be situated in northwesterly to westerly
upper level flow from Tuesday through the end of the next week. This
may allow for weak shortwaves to move overhead which could trigger a
few showers. However timing of these shortwaves is nearly impossible
at this time and in general most of northwest California will be
dry during this period. Thus have opted to keep chances for
precipitation below 15 percent Tuesday through Friday. /Rpa
Aviation...IFR to LIFR conditions and light winds to calm conditions
will continue at kcec and kacv through the early morning. The lower
conditions due to patchy fog reducing ceilings and/or visibilities.
IFR to MVFR conditions will prevail at kcec and kacv this afternoon.
VFR conditions and calm conditions will continue at kuki through the
early morning. VFR conditions and light to moderate winds will prevail
at kuki this afternoon.
Marine...light to moderate winds will continue today. A weak cold
front will approach the region this afternoon and move through the
waters this evening. Northerly winds will prevail across the waters
tonight through this weekend in the wake of the front. Winds and seas
will increase tonight and Saturday. Small craft advisories are likely
across the southern outer waters Saturday through early next week due
to increasing winds and seas. Small craft advisories are likely across
the northern outer waters Sunday through early next week. Small craft
advisories may be necessary across the southern near shore waters
Northwest California coastal waters...none.
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