109
FXUS66 KLOX 101732
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1032 AM PDT Mon Jun 10 2024

.SYNOPSIS...10/925 AM.

Temperatures will warm through Tuesday with better clearing each
day. After a brief cooling trend Wednesday and Thursday with
possible morning drizzle, widespread warmer temperatures are
expected Friday through next weekend with gusty northerly to
northwesterly winds.

&&

.SHORT TERM (TDY-WED)...10/938 AM.

***UPDATE***

A weak upper low about 300 miles southwest of KLAX continues to
spin away from the area, leading to rising heights and a warming
air mass. Onshore gradients have also decreased by 2-4 mb today so
the expectation is still for faster clearing today and warmer
temperatures, though some beaches may still remain cloudy and
cool well into the afternoon.

Forecast soundings are indicating significant lowering of the
marine layer Tuesday, which makes sense given the upper pattern
and gradient trends. Daytime highs expected to rise a few more
degrees, especially inland, with highs in the lower 100s in the
Antelope Valley and around 90 in the warmer coastal valleys.
Expecting the marine layer depth to drop to around 1500 feet in
the LA Basin and under 1000 feet along the Central Coast. Still
likely some morning low clouds into the valleys tomorrow but
clearing off much faster.

***From Previous Discussion***

With lower onshore flow through Tuesday, southwesterly winds are
expected to lighten up somewhat over the Antelope Valley and
foothills. Wednesday, as gradients are expected to increases,
gusty winds are likely to return.

.LONG TERM (THU-SUN)...10/331 AM.

Thursday into Friday the low will track eastward across the area,
with the center expected to remain south of Los Angeles County.
This system lacks significant moisture and the highest amount of
vorticity will occur overnight, so afternoon showers/thunderstorms
over the mountains are unlikely. However, some low impact cumulus
clouds may develop Thursday afternoon over high terrain. There is
a good chance of drizzle Thursday morning when lowering heights
are likely to lift the marine layer. There will continue to be a
chance for drizzle Friday and Saturday when heights rise again,
compressing the marine layer.

Temperatures will keep trending downward for Thursday, because
onshore pressure gradients are expected to continue to increase
while upper level heights lower. Low clouds and fog will extend
far inland overnight and be slow to clear with strong onshore
flow. There is however a chance that the cold air aloft will
disturb the capping inversion above the marine layer, causing low
clouds to scatter out across the region.

Friday through the weekend will see a significant change in the
overall pattern. Dry NW flow will move into the area and hgts will
rise to 587 dam. Temperatures will trend upward through Saturday
with little change on Sunday. A strong NW to SE pressure gradient
will develop across the eastern Pacific and wind will increase
greatly. The winds appear strongest over the coastal waters and
the Santa Barbara South Coast, with a significant chance of
Sundowners Winds (and Gale Force winds for the waters). Northerly
pressure gradients will shift offshore Friday night (peaking
around 3 to 4 mbs), which will drive the north to northwesterly
winds at the surface. In conjunction, easterly onshore gradients
will weaken at this time. This trend will drive up daytime highs
by minimizing the influence of marine layer clouds/seabreezes and
increasing warm downslope winds (especially for the Santa Barbara
South Coast). For the weekend, expect in the 90s across the
interior and warmer valleys, 80s for the coastal valleys, and mid
to upper 70s at the coasts.

&&

.AVIATION...10/1731Z.

At 1656Z at KLAX, the marine layer was 2300 ft deep. The top of
the inversion was at 3900 ft with a temperature of 19 degrees C.

For the 18Z TAF package, high confidence in desert TAFs and
moderate confidence in coastal and valley TAFs. Lower confidence
for coastal and valley sites due to uncertainties in marine layer.
Timing of flight category changes could be +/- 3 hours of current
forecasts.

KLAX...Moderate confidence in 18Z TAF. Timing of flight category
changes could be +/- 3 hours of current forecasts. Also, there is
a 20% chance of LIFR conditions 08Z-14Z time frame. No significant
easterly wind component is expected.

KBUR...Moderate confidence in 18Z TAF. Timing of flight category
changes could be +/- 3 hours of current forecasts. Also, there is
a 20% chance of LIFR conditions 08Z-14Z time frame.

&&

.MARINE...10/735 AM.

For the Outer Waters, high confidence in current forecast. Today
through Thursday, high confidence in winds and seas remaining
below Small Craft Advisory (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. Today through Thursday, high
confidence in winds and seas remaining below SCA levels. On
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. Today through Thursday, high
confidence in winds and seas remaining below SCA levels. On
Friday, there is a 30-40% chance of SCA level winds across the
western half of the Santa Barbara Channel.

The chance of gale force winds is increasing for next weekend and
will be monitored.

&&

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

&&

$$

PUBLIC...MW/Schoenfeld/Rorke
AVIATION...RAT
MARINE...RAT
SYNOPSIS...MW/Hall/RS

weather.gov/losangeles

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