Scientific Forecaster Discussion

Return to Local Conditions & Forecast
Area forecast discussion 
National Weather Service San Diego California
350 am PDT Friday Apr 18 2014

Synopsis...
a weak low pressure system moving inland through Southern California
will bring abundant middle and high clouds today with a slight chance
of showers over the mountains and upper deserts. Slow inland warming
for Saturday with greater inland warming for Sunday and Monday under
high pressure. The marine layer and onshore flow will continue areas
of night and morning coastal low clouds and fog. For Tuesday and
Wednesday...a stronger trough of low pressure will move inland along
the West Coast bringing cooling...deepening of the marine
layer...and strong gusty west winds in the mountains and deserts.
Weaker winds and modest warming for next Thursday and Friday.

&&

Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
counties...

Upper level low pressure centered over the California bight will
move into Southern California this afternoon and into Arizona
Saturday as it weakens. There is a flow northward of abundant middle
and high level moisture from northern Baja California and the adjacent eastern
Pacific coastal waters into Southern California. Some light showers
are possible today...mainly over the mountains and upper deserts.
And given a dry subcloud layer...there could be gusty downdraft
winds with showers or virga. West of the mountains...the marine
layer is around 3500 feet deep with the cloud layer about 1500 feet
deep so some patchy drizzle west of the mountains cannot be ruled
out for this morning.

For Saturday through Monday...high pressure will bring a warming
trend inland with a slowly decreasing marine layer depth with night
and morning low clouds and fog still extending inland into portions
of the valleys.

For Tuesday and Wednesday...a stronger trough of low pressure will
move inland along the West Coast bringing cooling...a deeper marine
layer...and strong gusty west winds in the mountains and deserts.
With the current trough amplitude...any precipitation would mostly
remain north of Point Conception. Slow warming and weaker winds for
Thursday and Friday of next week under weak high pressure.

&&

Aviation...
180900z...the coastal basin will be filled with low clouds with
bases around 2500 feet above sea level rising to around 3000 feet. Tops will
rise to over 5000 feet. That will mean some coastal slopes will be
obscured in fog. These will partially scatter out by 18-19z...but
some broken ceilings around 3000 feet will continue through the day.
Meanwhile higher clouds at or above 12000 feet above sea level will continue today over
all areas. In the mountains there is a slight chance of high based
convection and virga that could produce an isolated downdraft gust
to 30 knots today. Low clouds will redevelop in and fill the entire
coastal basin during the evening with bases around 2500 feet above sea level.

&&

Marine...
no significant marine weather conditions through Monday.
Strong northwest winds will arrive Tuesday and increased northwest
swell will follow Tuesday night.

&&

Skywarn...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.

&&

Sgx watches/warnings/advisories...
California...none.
Pz...none.

&&

$$

Public...17
aviation/marine...mm