Scientific Forecaster Discussion
Southwest California area forecast discussion...update
National Weather Service Los Angeles/Oxnard California
950 PM PST Friday Jan 30 2015
..updated aviation discussion...
A ridge of high pressure is expected to build in on the weekend...
with breezy offshore winds in some areas at times. Temperatures
should peak on Sunday and vary little through midweek. A cold front
may approach the central coast by the end of next week.
Short term (tonight-mon)...a few thunderstorms developed over
vtu/l.A. Counties this afternoon in response to a weak upper level
disturbance and some instability increased with afternoon sunshine.
This activity dissipated by early evening with just a few lingering
showers noted over parts of l.A. County. Any leftover showers will
end by middle evening with varying amounts of middle level clouds
lingering mainly over vtu/l.A. Counties. Low clouds did form along
the central coast and spread into the Santa Ynez Valley this
evening...and also developed over the Oxnard plain...but offshore
flow should clear these clouds out of this area after midnight. Low
clouds are also possible later tonight for the l.A. County coast. In
the Salinas River Valley...low clouds and patchy dense fog should
form by morning.
An upper level low over southeastern California this evening will move very slowly east
overnight...then S while weakening on Sat. An upper level ridge will
build into northern California Sat then move into Southern California for sun and Monday. Some
lingering middle level clouds are expected over vtu/l.A. Counties Sat
morning then diminish in the afternoon. Otherwise...mostly clear
skies are expected across the region through Monday. However...the 00z NAM
was hinting at the possibility of low clouds along the coast S of
Point Conception Sun night into Monday morning thanks to an eddy over
the socal bight. Offshore flow will increase by Sat morning...with
gusty winds expected mainly over the l.A. County mountains and in the
Antelope Valley. However...winds should remain generally below advisory
levels...except approach advisory levels in the mountains offshore winds
will increase again Sat night into Sun morning...with the strongest
winds in the l.A. County mountains and some foothill areas of vtu/l.A.
Counties. Winds may approach advisory levels at times in these
areas. Lingering offshore flow can be expected mainly over slo/sba
counties Sun night into Monday morning. Temperatures across the region are
forecast to be several degrees above normal in all areas Sat through
Monday...although it looks like sun will be the warmest of the three days.
***From previous discussion***
Long term (tue-fri)...not much weather to talk about in the long
range. Very little change in temperatures expected as a ridge
remains in place. The ridge builds a bit on Wednesday and Thursday
with a trough approaching from the west. Models agree that a cold
front will try to take a run at the central coast late in the
week...before a ridge develops again for next weekend. A slight
chance of rain may need to be added to the central coast for Friday
if the latest European model (ecmwf) is right. For now kept chances of rain below 20
At 0430z...there was no marine inversion present at klax.
Generally hi confidence in the 06z tafs. For kprb...a period of LIFR
ceilings/visibilities should affect the airfield about 13z-19z Sat. At klax and
klgb... MVFR ceilings are expected late tonight and Sat morning...although
there is a 30 percent chance of this not occurring. At ksmx...there
is a 30 percent chance of MVFR ceilings at times tonight. Otherwise...
VFR conditions are expected at all of the southwestern California airfields through Sat
evening. In addition...gusty NE winds are likely at kwjf and kpmd
Sat afternoon into early evening.
Klax...generally hi confidence in the 06z taf. VFR conditions are
expected through Sat night...except for a period of MVFR ceilings 12z-18z
Sat...although there is a 30 percent chance of no low ceilings developing.
Kbur...generally hi confidence in the 06z taf. VFR conditions are
expected through Sat afternoon. North winds around 12 knots are also
expected to develop Sat afternoon and persist into early evening.
Small Craft Advisory conditions for northwest wind and seas around
10 feet from Piedras Blancas to Point Sal from 10-60 nm and from the
outer waters from Point Sal to San Clemente Island will likely
persist through late tonight. Otherwise a broad area of low pressure
will continue to deepen while remaining nearly stationary over the
central Pacific through Saturday evening and then persist through
Sunday. Gale force winds within a fetch area oriented between
290-300 degrees relative to Ventura County is expected to generate
seas around 20 feet. And the swells from the fetch area are expected
to arrive next week Tuesday and remain below Small Craft Advisory for hazardous
Small Craft Advisory (see laxmwwlox).