Area Forecast Discussion
Issued by NWS Los Angeles, CA

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945
FXUS66 KLOX 240720
AFDLOX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1100 PM PDT MON MAY 23 2016

New Aviation Discussion

.SYNOPSIS...

A broad low pressure system will remain over the region into
midweek for breezy winds and below normal temperatures. A cool
weather pattern will prevail with a few showers at times. A high
pressure system should begin to build in on Thursday for normal
temperatures into the weekend.

&&

.UPDATE...

Locally gusty Sundowner winds have developed across Southern
Santa Barbara County this evening. With KSBA-KSMX gradients a tad
weaker than last night, winds are expected below advisory level
winds.

A broad trough remains over the West Coast this evening per the
latest water vapor imagery. A shortwave trough moving around the
broader trough circulation is currently located about 400 miles
west-northwest of Los Angeles. The shortwave trough and its
associated jet streak will wrap around the trough and nose into
the South Coast Basin after midnight tonight. With some clouds
developing on infrared satellite this evening ahead of the upper-
level feature and an eddy circulation remaining intact, mentions
of showers have been added to the forecast. The instability aloft
could interact with the expanding stratocumulus deck across the
South Coast Basin to bring mainly isolated showers to the coast,
valleys, and mountains.

Strong onshore flow in place and a bit better upper-level wind
support with the vorticity maximum could bring advisory level
winds to the Antelope Valley on Tuesday afternoon and evening.
The next shift will be briefed about the wind possibilities.

&&

.PREV DISCUSSION...

SHORT TERM...By late morning Tuesday with the added low lvl
moisture most areas should at least have more clouds with cooler
daytime highs. Again, a very small chance of a
sprinkle/drizzle/light shower around with the deep inversion. With
the daytime heating and lift from the onshore flow clouds should
increase over the mtns with some isolated light showers there.
Stability parameters were very poor in the models for tomorrow
(and Wednesday), possibly just due to too much cloud cover, but
didn`t feel like there was much chance of thunder so that`s been
removed.

A second upper low dumbbells around the trough and moves through
Wed morning. Here again no real organized features to really have
much confidence in. A little moisture mainly below 850 mb again
with the flow shifting to northwest behind the trough in the
afternoon. And again a very weak marine inversion making it a
tricky sky cover forecast. Overall partly cloudy, maybe some
periods of mostly cloudy, perhaps an isolated light
sprinkle/shower, mainly near the mtns.

Air mass starts to dry out Wednesday night as the trough finally
exits to the east and a very brief low amplitude ridge develops
over California. Should be a sunnier day Thu with little threat
of any precipitation. Perhaps some afternoon clouds over the mtns
with highs a few degrees warmer than Wed.

LONG TERM...The little warming trend will continue into Friday
before a weak trough returns for the weekend. Minimal impacts
locally other than a cooling trend through early next week with a
deepening marine lyr.

&&

.AVIATION...

24/0600Z

At 06Z AT KLAX there was no marine layer.

Low confidence in TAFs due to a weak marine layer. There is a 40
percent chc of no MVFR conds for all TAFs KSBA and south. There is a
better chance of low VFR BKN conds later this morning and afternoon.

KLAX...Low confidence in TAF. There is a 40 percent chc of no cigs
through 17Z. Better chc of VFR cigs after 17Z but could range
anywhere from 035 to 080.

KBUR...Low confidence in TAF. There is a 40 percent chc of no mvfr
cigs.

&&

.MARINE...

23/900 PM

Winds will diminish some between late tonight and Tuesday night.
There is a 30 percent chance that the Small Craft Advisory could
be extended through Tuesday evening. Widespread advisory level
winds are expected across the outer waters from Wednesday evening
through at least Friday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 AM PDT Tuesday For
      zones 650-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Hall/MW
AVIATION...ASR
MARINE...Hall
SYNOPSIS...Seto/Hall

weather.gov/losangeles



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