Scientific Forecaster Discussion
Southwest California area forecast discussion
National Weather Service Los Angeles/Oxnard California
140 PM PDT Friday Jul 3 2015
The approach of a low system will deepen the overnight marine layer
and cool the coastal and valley areas over the weekend. The
temperatures will be around normal through next week. The low will
move in by midweek to increase the night to morning clouds and fog
with additional cooling.
Short term (today-mon)...quiet day with minimal cumulus development over
the interior as most of the middle level monsoon moisture has exited
the area. A fair amount of very high level moisture is moving into
southeastern California but aside from some high clouds this won't
be posing any threat and is expected to shift east into Arizona by
Otherwise, just a typical early Summer weather regime this weekend
with a 1500-2000' marine layer that will linger along the coast each
day but clear most of the valleys and inland coastal plain by middle to
late morning. Temperatures today generally running cooler with 24 hour
changes running anywhere from 0 to -8. Expect just minor changes
through Sunday as the upper low off our coast drifts slowly north
and high pressure to our east continues to weaken and drift away.
Southeast flow will shift to southwest and keep our area out of the
monsoon flow. Might get a few afternoon cumulus over the mountains but nothing
more than that.
On Monday there is a very slight bump in heights/thicknesses as that
upper low off the coast shifts north allowing some very brief and
weak ridging to develop so there could be a slight jump in temps,
mainly inland, but probably not even enough to notice.
Long term (tue-fri)...minimal changes Tuesday from Monday. Models
have been consistent last few days showing that upper low getting
picked up by the westerlies and pushed into northern and central
California by around middle week. This will likely bring about a deeper
marine layer and cooler temperatures all areas Wed/Thu. By Friday the trough is
gone and weak ridging returns for a warming trend going into the
weekend. No threat of monsoon thunderstorms for the next 10 days at
least as the flow aloft is from a dry southwest direction.
At 1550z...the marine inversion at klax was 1600 feet deep. The top of
the inversion was at 2500 feet with a temperature of 22 degree c.
Fairly good confidence in the 18z tafs. As expected...the marine
clouds have returned to the coastal sections and with further marine
layer deepening today and tonight will reclaim more territory by
spreading into the valleys Saturday morning. MVFR conditions are
expected in the coastal sections while IFR conditions are the likely
result in the valleys. Increasing onshore flow across the forecast
area will insure some gusty southwest winds across the Antelope
Valley in the afternoons for the next few days.
Klax...good confidence in the 18z taf. There is a 30 percent chance
of total clearing for this afternoon. There is a 30 percent chance
the marine clouds will arrive later than forecast.
Kbur...good confidence in the 18z taf. There is a 30 percent chance
of VFR conditions through the night.
There may be some local Small Craft Advisory level wind gusts across the outer waters
during the afternoon and evening hours through Sunday. There is a 20
to 30 percent chance that Small Craft Advisory level winds will become widespread
enough to require advisories during the afternoon and evening hours
each of the next three days...mainly across the southern two thirds
of the outer waters.
high rip current risk (see laxsrflox).