004
FXUS66 KLOX 141637
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
937 AM PDT Tue May 14 2024

.SYNOPSIS...14/843 AM.

Generally stagnant pattern through early next week with little
day to day changes. Persistent low clouds and below normal
temperatures will dominate the coastal side of the mountains, with
above normal temperatures and gusty onshore winds on the interior
side. The only wrinkle is a low chance of showers in the
mountains each afternoon through Wednesday.

&&

.SHORT TERM (TDY-THU)...14/843 AM.

***UPDATE***

A typical May marine layer, with depths between 1500 and 3000
feet, maintains its stronghold over the area. Expecting another
cool and gloomy day on the coastal side of the mountains, as
healthy onshore pressure gradients remain. Modified the high
temperature forecast a bit to lower some coastal and valley areas
to similar values as yesterday. Onshore wind gusts will increase
and expand over the interior areas as they have been each day,
with gusts of 20 to 35 mph common (strongest in the Antelope
Valley with local gusts to 40 mph possible).

A weak but present upper level low right over southern California
will weakly destabilize the atmosphere today and Wednesday. While
the moisture aloft is the main limiting factor, there is a little
(850mb dewpoints around 8 degrees Celsius). In addition, the
convective clouds and moisture currently over southern Nevada and
northwest Arizona will move over our area later tonight into
Wednesday morning. These clouds could inhibit the convective
potential some tomorrow, but if they thin out in the afternoon
like the computer models suggest, then this could instead provide
an extra moisture boost to the convection potential. As a result,
upped the chances of showers to 20 percent for the typical shower
magnets in the San Gabriel Mountains and north Ventura Mountains.
While not explicitly in the forecast, there is also a 10 percent
chance that any shower grows into a thunderstorm.

***From Previous Discussion***

The relentless May Grey pattern will continue unabated. An upper
low will transit over the area NW to SW today and Wednesday with a
very weak ridge on tap for Thursday. Day to day gradients will
change little and there will be a strong 8+ mb push to the east
and moderate 5+ mb push to the north in the afternoons.

The low cloud pattern will continue with all coasts and vlys
socked in the morning followed by decent clearing for the vlys,
slow clearing for the inland coastal areas and brief late
afternoon or no clearing for the near shore areas. Mdls do show
slightly better/faster clearing on Thursday due the ridge, but
given the strength of the onshore flow this might prove to be a
little optimistic.

The strong onshore gradients will generate gusty southwesterly
winds across interior sections, including the Antelope Valley.
However, outside of the local wind tunnels like Lake Palmdale, do
not expect any widespread advisory-level gusts for the area.

There will be some build ups each afternoon over the higher peaks
where the differential heating will generate decent instability.
Today and Thursday there is high confidence that there will only
be some CU formation today and Thu. A few Hi Rez ensemble
forceast members do show a wave moving in from the NE Wednesday
afternoon and there is a 10 percent chc that this could trigger
some TSTMs across the LA and VTA mtns.

It will be a little cooler today as hgts fall. Max temps will
change little Wednesday and then warm some as hgts rise on
Thursday. Max temps will generally be in the mid 60s to lower 70s
across the coasts and 70s through the vly. The inland areas will
be much warmer with max temps in the 80s. As it has been for the
last few day the csts/vly will be 3 to 6 degrees blo normal and
the inland areas will wind up 3 to 6 degrees above normals.

.LONG TERM (FRI-MON)...14/307 AM.

On Friday the upper level ridge will peak in strength. This
should result in some slightly warmer temperatures and less
extensive marine layer clouds and fog.

An upper level low or trof will move up from the SW on Sat and Sun
and will move over the area on Monday. The hgts will low through
the period and onshore flow will increase into the moderate to
strong category again.

Look for extensive night through morning low clouds through the
period with enough present on Sunday to warrant a chance of
drizzle in the morning.

The gradients are strong enough to bring a chc of advisory level
gusts to portions of the LA mtns and the western Antelope Vly and
adjacent foothills.

There will be a decent for this time of year jet in the area on
Sunday afternoon which is always a convective worry, but right now
none of the ensembles show it having any effect. Still it is worth
watching.

Look for three days of cooling with Monday`s max temps coming in 4
to 8 locally 10 degrees below normal (vly temps only in the lower
to mid 70s)

&&

.AVIATION...14/1637Z.

At 1630Z at KLAX, the marine layer was 2700 feet deep. The
top of the inversion was around 3600 feet with a temperature
of 17 degrees Celsius.

Overall for the 18Z TAF package, high confidence in desert TAFs
and moderate confidence in coastal/valley TAFs. Lower confidence
for coastal/valley sites due to uncertainties with timing of
dissipation and formation of stratus.

KLAX...Moderate confidence in 18Z TAF. There is a 20-30% chance
that MVFR CIGs will not dissipate this afternoon. Timing of flight
category changes could be +/- 2 hours of current forecast. No
significant easterly wind component is expected.

KBUR...Moderate confidence in 18Z TAF. Dissipation of MVFR CIGs
could be as late as 21Z. Return of MVFR CIGs could be +/- 2 hours
of current 06Z forecast. Also, there is a 30% chance of IFR CIGs
08Z-14Z.

&&

.MARINE...14/759 AM.

For the Outer Waters, moderate to high confidence in current
forecast. Today through Saturday, conditions will remain below
Small Craft Advisory (SCA) levels for most of the Outer Waters.
The only exception will be the area around Point Conception where
there is a 30-40% chance of SCA level winds Wednesday and
Thursday.

For the Inner Waters north of Point Sal, high confidence in
current forecast. Today through Saturday, winds and seas will
remain below SCA levels.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. For most of the southern Inner
Waters, winds and waves will remain below SCA levels through
Saturday. The only exception is the western half of the Santa
Barbara Channel where there is a 30-40% chance of SCA level winds
each afternoon and evening today through Thursday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC...Rorke/Kittell
AVIATION...RAT
MARINE...RAT
SYNOPSIS...RK

weather.gov/losangeles

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