161
FXUS66 KLOX 131807
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1107 AM PDT Sat Jul 13 2024

.SYNOPSIS...13/900 AM.

Scattered showers and thunderstorms are expected today, especially
across the interior. The long-lasting heat wave across the
mountains and interior areas will end today as the high pressure
system weakens and pushes to the east. There will be some cooling
each day through the middle of next week. In the meantime,
temperatures inland will remain above normal. Another warming
trend will develop later next week and continue into next weekend.

&&

.SHORT TERM (TDY-MON)...13/911 AM.

***UPDATE***

Scattered showers and thunderstorms developed last night and
continue this morning. Most of the activity currently is focused
across western Ventura County and north with a lull across LA
County. However, satellite imagery shows an area of showers and
storms over the southeast deserts moving towards the northeast.
The trajectory of this would bring it into eastern LA County and
particularly the eastern San Gabriels and Antelope Valley area by
this afternoon, similar to what the hi res models have been
indicating since yesterday. So far there has been very little rain
reaching the ground with any of the storms, which was expected
given the high based moisture. With daytime heating and some
additional energy moving in from the southeast this afternoon
updraft strength will increase and there could be some heavier
showers at times reaching the ground, especially at higher
elevations. The biggest impact today will likely be dry lightning
and gusty winds but can`t totally rule out isolated flooding with
the bigger storms later today, especially in the Antelope Valley.

***From Previous Discussion***

The upper high remains near the four corners area on Sunday. Hgts
fall enough to bring a degree or 2 of cooling to the area. The
onshore gradients do not change much and the low cloud pattern
should be similar today. Not totally out of the woods as far as
convection is concerned but it looks like all of the moisture will
be around 600mb so a non zero but less than 12 percent chc of a
shower in the afternoon more likely just a bunch of build ups. Max
temps will only be 4 to 6 degrees above normal and near normal
across the coasts and vlys.

On Monday the east Pac trof pushes close enough to the coast to
switch the flow the SW which will dry things out and eliminate the
convective threat. Otherwise a pretty dull day with coastal low
clouds in the morning and otherwise clear skies. Max temps will be
similar to Sunday`s.

.LONG TERM (TUE-FRI)...13/337 AM.

Tuesday will be the coolest day of the next 7 as the east Pac
trof makes it`s closest approach to the coast. Hgts fall to about
592 dam and the onshore flow increases to the highest value of
the week. Max temps will fall another couple of degrees. Most max
temps will end up 2 to 4 degree blo normal save for the Antelope
Vly which will remain 2 or 3 degrees above normal.

The the upper high will build back to the west and hgts will
increase and temps will rise. Look for a couple of degrees of
warming each day Wed through Saturday. Onshore flow will continue
and there will be night through morning low clouds across the
coasts. Barring an unforeseen eddy the vlys will remain cloud
free. The marine layer will keep the coasts cooler but the vlys
will be about 5 degrees above normal by Saturday and the interior
will be about 10 degrees. Right now it looks like the monsoon will
keep to the east but this could change.

&&

.AVIATION...13/1806Z.

At 18Z at KLAX, the marine layer was 1800 feet deep. The top of
the inversion was at 5800 feet with a temperature of 25 deg C.

There is a low, but non-zero chance of isolated thunderstorms at
all sites 18Z Sat-06Z Sun.

Moderate confidence in TAFs for KPRB, KPMD, and KWJF. For these
sites, there is a 20% chance for thunderstorms 18Z Sat-06Z Sun.

Moderate confidence in coastal TAFs. Cig hgts may be off by +/-
300 ft. Flight cat transitions may be off by +/- 2 hours.

KLAX...Moderate confidence in TAF. Flight cat transitions may be
off by +/- 2 hours. No significant easterly wind component is
expected.

&&

.MARINE...13/822 AM.

Small Craft Advisory (SCA) conditions are not expected through
the weekend. There is a 30-40% chance of SCA winds across the
Outer Waters starting Monday afternoon through the week.
Additionally, there is a 20-30% chance of SCA winds across the far
western portion of the Santa Barbara Channel during each
afternoon through overnight hours beginning Monday through the
week. A long period south swell is expected to arrive Tuesday and
may lead to a chance for elevated surf conditions and high rip
current potential through Thursday.

Isolated thunderstorms are possible (about a 20% chance) through
the day, and lightning has already been observed this morning.
Any thunderstorm that forms will be capable of producing locally
gale force winds, rough seas, and dangerous lightning.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning remains in effect until 9 PM PDT this
      evening for zones 38-343>345-353-376>379-381>383. (See LAXNPWLOX).
     Fire Weather Watch in effect until 9 PM PDT this evening for
      zones 342>345-348-351>353-376>383. (See LAXRFWLOX).
PZ...NONE.

&&

$$

PUBLIC...MW/Rorke
AVIATION...jld
MARINE...Lund/jld
SYNOPSIS...MW

weather.gov/losangeles

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