Southwest California area forecast discussion
National Weather Service Los Angeles/Oxnard California
820 PM PDT Thursday may 23 2013
Synopsis...
Breezy winds will continue tonight across the mountains and deserts.
An area of low pressure will linger over the region through Tuesday
with persistent night through morning cloudiness and fog. Gusty winds with
possible precipitation on Monday night into Tuesday night for most
areas. The afternoon temperatures will remain below normal through
next Tuesday...then a warmup to seasonal normals by midweek.
&&
Short term (tonight-sun)...
mostly clear skies across the forecast area this evening...with low
clouds currently confined to portions of Orange and San Diego
counties. A persistent upper level trough and strong onshore flow
brought additional cooling to the region today. Another round of gusty
west to northwest winds felt across the district today...although wind
speeds have generally been less than yesterday. With winds dropping
below advisory levels across the Antelope Valley and central coast...will
be dropping those advisories at 9 PM update.
Current acars data showing a weakened marine inversion with a depth
around 4000 feet. This weakened inversion has allowed for good clearing
today. Latest 00z NAM model continues to develop an eddy circulation
overnight...with low clouds likely filling in once again across much
of the Los Angeles and Ventura counties...locally extending into the
lower coastal slopes.
*** From previous discussion ***
Very little changes for the weekend. The low pressure system over
the Pacific northwest remains stationary with heights remaining
static over Southern California through Sunday. Temperatures will be a
couple of degrees higher than today but that's about it. Night and
morning low clouds and patchy fog should return along the South
Coast and reorganize along the central coast over the weekend.
Long term (mon-thu)...
the long range becomes a little more fuzzy with lower forecast
confidence for Monday and Tuesday. With the Pacific northwest low
pressure system stalling out...this allows time for a stronger
northwest jet stream to reach the eastern Pacific and dig down the
backside of the low pressure trough. By Tuesday morning this jet
stream is rapidly pushing 90+kts along the central coast as the
trough amplifies across the Great Basin. The European model (ecmwf) has been the most
aggressive for the past two runs...but the GFS is also showing
enough to warrant a slight chance of showers late Monday night
through Tuesday evening. Gusty northwest winds may turn out to the
bigger story for the central Coast...Mountains...and av during this
time frame. The trough looks progressive and should clear Southern
California by Wednesday but it may remain rather windy in places. Expect
temperatures to be below normal early in the week then warming as a
ridge builds in mid-week.
&&
Aviation...23/2335z.
Satellite imagery showing some stratocumulus clouds lingering across the
la County valleys and mountains this afternoon...otherwise skies are mostly
clear. A persistent eddy circulation is expected to maintain low clouds
across much of the la basin tonight...potentially spreading into portions
of Ventura County late. Only 20 percent chance of low clouds redeveloping
along central coast. Gusty onshore winds continue across central coast
and Antelope Valley...however speeds are not as strong as yesterday.
Klax...high confidence that MVFR ceilings will return at some point
tonight...but low confidence in timing. A 10% chance that VFR conditions
could linger through the night.
Kbur...high confidence that MVFR ceilings will return at some point
tonight...but low confidence in timing. A 10% chance that VFR
conditions could linger through the night.
&&
Lox watches/warnings/advisories...
Gale Warning (see laxmwwlox).
Small Craft Advisory (see laxmwwlox).
High rip current risk (see laxsrflox).
&&
$$
Public...gomberg/boldt
aviation...Smith
synopsis...seto
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