Southwest California area forecast discussion
National Weather Service Los Angeles/Oxnard California
142 PM PDT Tuesday may 21 2013
Synopsis...
A cooling trend that began for most areas today will continue
through the weekend along with an increase in night through morning
low clouds and fog. Breezy conditions are expected along the central
coast...southern Santa Barbara County...Interstate 5 corridor...and
the Antelope Valley.
&&
Short term (today-fri)...a strong onshore push today brought
cooling to most areas except some of the mountains and Antelope Valley.
This will continue and spread further inland through the weekend as
a persistent trough sets up along the West Coast. Slight deepening of
the trough is expected Wednesday and Thu, and this combined with a
strengthening eddy circulation (thanks to increasing outer water
winds) will possibly be enough to generate some drizzle during the
overnight hours across Ventura and la counties. That increase in
northwest flow around pt Conception and through the Santa Ynez range
will likely keep low clouds out of southern sba County the next few days
with warmer temperatures there. Winds will be close to or locally exceeding
advisory criteria for southern sba County, the i5 corridor and the
Antelope Valley starting late Wednesday.
If the models are to be believed, the trough briefly lifts on Friday,
resulting in a very slight warming trend Friday, maybe a few degrees
at most, and earlier marine layer clearing.
Long term (sat-tue)...trough deepens again over the Holiday weekend.
Decreasing northwest flow should allow the low clouds to spread up
the coast through slo County and we may see areas of drizzle again
each morning through Monday. Limited coastal clearing and clouds may
linger into early afternoon for some of the valleys. Daytime temperatures
expected to run 2-4 degrees below normal. The trough is expected to
shift east Tuesday for a warming trend going into the middle of next
week.
&&
Aviation...21/1800z.
Overall confidence in the 18z taf package is moderate. Moderate to
high confidence that all taf sites will remain in VFR conditions
through early this evening. A trough will move through the area
today and increased northerly flow will help this. For tonight and
tomorrow morning...moderate to high confidence that most sites north
of koxr will remain VFR due to the previously mentioned strong
northerly flow and even some northeast flow on the central coast.
There is a 30% chance that ksmx will not see the ceilings that are
currently predicted. A Catalina eddy will spin up again tonight and
the marine layer will deepen for Los Angeles and Ventura
counties...so a similar cloud pattern is expected for these taf
sites tomorrow morning as to what was seen today. Less confident in
the koxr taf as there will be stronger northerly flow tomorrow
morning...which may make it difficult for the eddy to bring low
clouds that far north. There is a 30% chance that the forecasted
ceilings for koxr tomorrow morning will not develop.
Klax...moderate to high confidence in VFR conditions through early
this evening. High confidence that MVFR conditions will return for
tonight and tomorrow morning...however low to moderate confidence in
the exact arrival time.
Kbur...high confidence in VFR conditions through early this evening.
Moderate to high confidence that at least MVFR conditions will
return tonight and tomorrow morning...however low to moderate
confidence in the exact arrival time. There is a 20% chance that
ceilings could fall into the IFR category.
&&
Lox watches/warnings/advisories...
Gale Warning (see laxmwwlox).
Small Craft Advisory (see laxmwwlox).
High rip current risk (see laxsrflox).
&&
$$
Public...mw
aviation...Sweet
synopsis...kj
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