422
FXUS66 KLOX 100711
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1211 AM PDT Mon Jun 10 2024

.SYNOPSIS...09/856 PM.

Weaker onshore flow will bring a warming trend through Wednesday
as high pressure builds into the region from the east. Most of
the warming will be felt away from the coastal areas where onshore
flow will keep night through morning low clouds and fog in the
forecast. After a brief cooling trend Thursday, widespread warmer
temperatures are expected Friday through next weekend with some
gusty north winds at times.

&&

.SHORT TERM (MON-THU)...09/941 PM.

The latest satellite imagery shows an upper-level trough of low
pressure about 290 miles southwest of Los Angeles, while ridging
aloft is building into west Texas and southern New Mexico. The
trough will continue to move to the southwest away from the
region and allow for high pressure to the east to expand into the
area. A warming trend will take shape over the coming days as
ridging aloft will weaken onshore flow and thin the marine layer
depth some. Onshore flow is already weakening and the marine layer
stratus coverage is much less entrenched than the last several
days, partially due to the trough digging past the state to the
west. Night through morning low clouds and fog will remain as a
staple of the coastal and valley areas through midweek though as
onshore flow will remain in place. As a result, the best warming
will take place well away from the coast and outside the marine
layer depth.

The forecast keeps a mention of drizzle for tonight and into
Monday, despite the marine layer depth thinning some. Enough
dynamics from the trough continues to scrape the area through
Monday morning. The dynamics could lift the marine layer deck and
squeeze some drizzle.

An update to forecast will be issued shortly.

***From Previous Discussion***

Tuesday expected to be the warmest of this mini heat wave with
far interior areas like the Antelope Valley getting into the lower
100s (though not as warm as last week) and warmer coastal valleys
near 90. Forecast highs were trimmed slightly as offshore trends
have lightened the last few runs but still enough for warming in
most areas. Still expecting low clouds and fog for coastal areas
but clearing earlier.

Models currently showing onshore flow increasing again Wednesday,
however, this may be a little premature as the a majority of the
ensembles show the upper low not starting to move back towards the
coast until early Thursday. So it`s possible that forecast highs
on Wednesday are too cool, especially inland.

.LONG TERM (FRI-MON)...09/157 PM.

Cooler weather on tap Thursday as the upper low moves across the
area from southwest to northeast. The low has very little moisture
associated with it so not expecting any afternoon showers or
storms in the mountains, but some increase in cumulus clouds there
is a good bet. Marine layer will be deepening as the lows treks
through, possibly enough for some more morning drizzle for
coast/valley areas.

A significant warming trend is expected Friday and Saturday as
heights rise and the air mass warms following the departure of the
upper low. At the same time onshore flow to the east weakens and
actually turns offshore to the north by around 3mb. The GFS is
showing around 50kt of north to northwest winds near and west of
Pt Conception, and 25-40 kt over the western Santa Ynez Range.
Will have to monitor this situation closely through the week as
these conditions could create some fire weather concerns.
Elsewhere, warmer valleys are expected to reach the 90s and
inland coastal areas expected to be in the mid 70s to lower 80s.

&&

.AVIATION...10/0707Z.

At 0505Z at KLAX, the marine layer was 2000 ft deep. The top of
the inversion was at 4900 ft with a temperature of 19 degrees C.

High confidence in KPMD and KWJF.

Moderate confidence in KPRB where there is a 30 percent chc of IFR
cigs 11Z-16Z.

For all other sites low confidence in low cloud arrival timing but
high confidence that all sites will have low clouds by 13Z.
Moderate confidence in VFR transition with possible  clearing
occuring 1 hour earlier than fcst. Low confidence again Monday
evening with regard to stratus arrival.

KLAX...Moderate confidence in TAF. There is a 30 percent chc of
clearing by 19Z. There is a 30 percent chc that onset of low
clouds Monday evening will be as late as 08Z. No significant
easterly wind component is expected.

KBUR...Good confidence that low clouds will be in place at 13Z but
low confidence in exact arrival time. There is a 30 percent chc of
clearing by 17Z.

&&

.MARINE...09/820 PM.

For the Outer Waters, high confidence in current forecast, but low
confidence on marginal Small Craft Advisories (SCA). For tonight,
there is a 60-80% chance of Small Craft Advisory (SCA) level
winds. For Monday through Thursday, high confidence in winds and
seas remaining below SCA levels. On Friday, there is a 50-70%
chance of both SCA level winds and seas. For the Inner Waters
north of Point Sal, moderate to high confidence in current
forecast. Localized SCA conditions focused northern areas will
may continue through this evening. For Monday through Thursday,
high confidence in winds and seas remaining below SCA levels. For
Friday, there is a 40-50% chance of SCA level winds in the
afternoon and evening hours.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. For the western half of the Santa
Barbara Channel, there is a 30-40% chance of SCA level winds this
evening. Otherwise, high confidence in winds and seas remaining
below SCA levels through Friday for the Inner Waters south of
Point Conception.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 AM PDT early this
      morning for zones 670-676. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 AM PDT this morning
      for zone 673. (See LAXMWWLOX).

&&

$$

PUBLIC...Hall/MW
AVIATION...Rorke
MARINE...RAT/Munroe
SYNOPSIS...Hall

weather.gov/losangeles

Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox