752
FXUS66 KLOX 151953
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1253 PM PDT Mon Jul 15 2024

.SYNOPSIS...15/928 AM.

There is a chance of thunderstorms this afternoon over the Los
Angeles and Ventura County mountains and Antelope Valley,
otherwise skies will be clear except for morning low clouds across
the coasts. A cooling trend will continue through Tuesday, but a
warming trend starting Wednesday will lead to the possibility of
extreme heat across the interior by the weekend.

&&

.SHORT TERM (TDY-WED)...15/939 AM.

***UPDATE***

Airmass not quite as unstable as yesterday, though PW`s are around
the same or slightly higher than yesterday. And certainly not as
active across the southwest as it was yesterday at this time.
Still, with the NKX sounding showing PW`s close to 1.5" and
forecast CAPEs around 500j/kg isolated thunderstorms can`t be
ruled out across the eastern San Gabriels and Antelope Valley.
Upper level winds continue to veer more southwest which limits the
westward extent of potential thunderstorms, but will leave a
slight chance in for the northern Ventura mountains as well. In
general, probably not as active as yesterday but given the
potential for fire starts better to err on the side of caution.

Marine layer was 1800-2000 feet this morning, so a few hundred
feet deeper than yesterday, but overall less coverage south of Pt
Conception. With some stabilizing of the air mass overnight and
lowering PW`s we should see slightly greater coverage of stratus
Tuesday morning.

***From Previous Discussion***

Tuesday will be the coolest day of the next 7 as hgts fall in
response to a trof approaching from the west. The most noticeable
cooling will occur across the interior of SLO county. Max temps
will end up about 4 degrees blo normal across VTA and LA counties
(xcp for the Antelope Vly where max temps will be 3 degrees above
normals) and 4 to 8 degrees blo normal for SLO and SBA counties.

On Wednesday, model solutions continue to show the upper high
strengthening and pushing to the west. This will push up heights
and kick off a warming trend which will persist into next weekend,
especially for interior areas. Onshore flow will persist and there
will be morning low clouds at most of the coastal locations.

.LONG TERM (THU-SUN)...15/334 AM.

Both Deterministic and ensemble solutions agree that the upper
high will strengthen and push to the west. By Saturday it will be
over the southern NV/UT border. Heights will rise to near 596 dam
again. Max temps will rise 1 to 3 degrees each day Wed through
Fri. On Saturday the csts/vlys will cool a couple of degrees as
onshore flow increases. The interior will warm another 1 to 2
degrees.

Lower mtn elevations and the far interior will all have triple
digit heat on Saturday with the Antelope Vly topping out between
105 and 110 degrees. These Antelope Vly temps will likely bring
another round of Excessive Heat Warnings. The rest of the
interior, however, will likely come in just below warning
criteria.

Some cooling is forecast for next Sunday but both the EC and GFS
keep hgts similar to Saturday and would not be surprised if temps
remain similar esp inland.

There is no convection in the fcst but the upper high is in
position that there could be some monsoon flow at some point.

Onshore flow will keep the night through morning low cloud pattern
going through the period. The higher than normal hgts will keep
the marine layer shallow enough to preclude any vly penetration
unless a surprise eddy slins up. Toward the end of the week
onshore flow increases enough that some west facing beaches may
struggle to clear.

&&

.AVIATION...15/1816Z.

At 17Z at KLAX, the marine layer was 1200 feet deep. The top of
the inversion was at 4300 feet with a temperature of 25 deg C.

High confidence in TAFs for KPRB, KPMD, and KWJF. There is a 15%
chance of thunderstorms at KPMD and KWJF this afternoon through
evening.

Moderate confidence in KBUR and KVNY. There is a 20-30%
chance of IFR/LIFR conditions at KBUR and KVNY between 10Z and
15Z.

Low confidence in coastal TAFs. Flight categories changes may be
off +/- 3 hours. VFR conditions likely at most coastal sites
through the afternoon, with conditions becoming IFR to LIFR at
most sites. There is a 20% chance of LIFR conditions at KSBP,
KSBA, KOXR, and KCMA.

KLAX...Moderate confidence in TAF. Cigs between 800 and 1000 feet
likely to arrive after 03Z and persist thru at least 18Z. Vsbys
should remain VFR, but there is a 10% chance of LIFR conditions
during the period. Flight category changes could differ +/- 2
hours. No significant east wind component expected.

KBUR...Moderate confidence in TAF. There is a 20% chance that
cigs and vsbys could arrive between 10 and 15Z. Cigs below 500ft
and vsbys below 3SM would be likely if they reach the valley.

&&

.MARINE...15/1250 PM.

In the southern outer waters (zones PZZ673 and PZZ676), there is
a Small Craft Advisory (SCA) from 3 PM this afternoon through 3 AM
Tuesday.

In the northern zone (PZZ670), there is a 30% chance of SCA winds
beginning Wednesday afternoon. SCA winds likely (70%) beginning
Thursday and remaining at all hours thru at least Saturday night.

30% chance of SCA winds in the southern two outer zones (PZZ673/676)
Tuesday night thru Wednesday morning. 70% chance SCA conds
begin Wednesday afternoon and persist at all hours thru at least
Saturday night.

In the inner waters N of Pt. Sal (Zone PZZ645), SCA conditions
are not expected thru Wednesday. There is a 30% chance of SCA
conditions beginning Thursday afternoon and persisting in the
afternoon/evening hours thru at least Saturday.

In the inner waters S of Pt. Conception, there is a 30% chance of
SCA winds across the far western portion of the Santa Barbara
Channel (Zone PZZ650) tonight thru early Tuesday morning. There is
a 20% chance of SCA winds in the afternoon and evening hours
Tuesday thru at least Saturday night. SCA conds are not expected
thru the forecast period for Zone PZZ655.

Areas of dense fog will reduce visibilities to below one mile thru
late this morning. There is a good chance that this will occur
during the night thru morning hours each day thru Wed or Thu.

&&

.BEACHES...15/507 AM.

A series of Southern Hemispheric storms will send a long-period,
S to SW swell (around 18-second wave periods) to the Southern
California coastal waters during early to middle parts of this
week. Wave periods will gradually shorten to around 15 seconds by
late week. In response to these developments, an extended period
of elevated surf -- surf heights of 4-6 feet -- along with
powerful and dangerous rip currents is likely (over 80% chance)
from Tue thru Thu. The area of greatest concern for these impacts
will be on beaches with highest exposure to a S to SW swell
directions -- especially on the L.A. and VTU County beaches.
These factors warrant the issuance of a Beach Hazards Statement
for the beaches of L.A. and VTU Counties.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect from Tuesday morning
      through Thursday evening for zones 354-362-366. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Tuesday for
      zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...MW/Rorke
AVIATION...Lewis
MARINE...Lewis/DB
BEACHES...Cohen/DB
SYNOPSIS...MW

weather.gov/losangeles

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