411
FXUS66 KLOX 081133
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
433 AM PDT Mon Jul 8 2024

.SYNOPSIS...07/1017 PM.

A long-lasting and extreme heatwave will continue across the
mountains and interior areas through much of the coming week as a
strong high pressure system remains anchored over the region. A
high risk for dangerous heat illness exists across the interior
portions of the area. Above normal temperatures are likely across
much of the area into late week, along with an increasing risk of
heat issues in the valleys towards the latter half of the week.

&&

.SHORT TERM (TDY-WED)...08/429 AM.

Strong high pressure aloft will continue to slowly move northeast
of the region through midweek. This high pressure, combined with
weakening onshore flow, will continue the very hot weather across
much of the region through midweek.

Due to little change in upper level heights, expecting the far
interior areas and mountains, including the Antelope Valley, to
remain very hot with daily high temperatures up to 115 through
Thursday. Temperatures across the coastal valleys are expected to
warm today by about 5-10 degrees compared to yesterday due to
onshore flow weakening and the shrinking of the marine layer.
Thus, have issued a heat advisory for the Ventura and L.A. Valleys
with temperatures of 93-103 degrees possible. Temperatures across
the coastal valleys/coastal mountains will further warm on
Tuesday as the onshore flow continues to weaken. The increase in
temperatures combined with limited night time relief, led to the
issuance of Excessive Heat Watches from Tuesday morning through
Thursday evening. Little change in conditions are expected Tuesday
through Thursday across the region.

As for clouds, the high pressure aloft has squashed the marine
layer over the past day, resulting in dense fog across the coastal
areas this morning. Thus, a dense fog advisory has been issued
through mid morning. Expecting clouds to burn off by late morning,
however there is a good chance that some beach areas remain at
least partly cloudy through the day. Tuesday and Wednesday should
be similar, though dense fog may not be as expansive and may be
patchy at most. However, better clearing during both days are expected
due to the weakening onshore flow. Developing northerly flow
along the Central Coast and southern Santa Barbara County will
likely limit or possibly eliminate the stratus in those areas
tonight. Increasing north winds Tuesday and Wednesday evenings in
southern Santa Barbara County and parts of the Santa Lucias may be
strong enough for some wind advisories as well as keep the low
clouds away both nights.

.LONG TERM (THU-SUN)...07/222 PM.

This very lengthy period of strong high pressure aloft only very
slowly weakens later this week into next weekend and deciding
which day to end the current slate of seemingly endless Excessive
Heat Warnings across the interior will be decided after
coordination with surrounding offices. For now have extended the
warnings there through Thursday which is about when high
temperatures start to reach or drop slightly below 110, but could
certainly see a case for going another day or two beyond that with
highs still 10-15 degrees above normal.

Similar situation for the valleys. There are no watches or
warnings currently in effect but the latest ensemble guidance is
leaning warmer and likely to stay 10-15 degrees above normal
through Thursday.

A slow cooling trend is expected to continue into next weekend,
however triple digit heat is possible in the valleys even into
next Sunday. Coastal areas will 2-5 degrees above normal Thursday,
then basically near normal next weekend with typical night and
morning low clouds and fog expected. Not really seeing any clear
signals of monsoon flow yet.

&&

.AVIATION...08/0017Z.

At 23Z at KLAX, the marine layer was 900 feet deep. The top of
the inversion was at 4200 feet with a temperature of 32 deg C.

High confidence in VFR TAFs for KPRB, KPMD, and KWJF.

Moderate confidence in forecast with flight category timing
possibly off by two hours and flight category off by one at times.
Except low confidence at KBUR and KVNY with a 40-50 percent chance
that VFR conds prevail. Highest confidence of LIFR conds for KSMX
and KSBP.

Fires in the region may lead to periods of 4-8SM HZ/FU at some
terminals, especially KOXR/KCMA and north.

KLAX...Moderate confidence in TAF. There is a 20-30% of at least
brief LIFR cigs/vsbys between 04-10Z. Good confidence in any east
wind component remaining under 5 kts.

KBUR...Low confidence in TAF with a 40-50% that VFR conds prevail.

&&

.MARINE...07/838 PM.

We have issued a Marine Weather Statement for areas of dense fog
that will continue for most of the coastal waters through at least
Monday morning. A low end Small Craft Advisory has also been
issued to cover the Outer Waters Monday evening through Wednesday
night.

In the Outer Waters, winds are expected to remain below SCA
levels thru Mon morning. There is a 50-70% chance of SCA conds
Monday evening through Wednesday night, although there will likely
be lulls in SCA conds each morning.

In the inner waters N of Pt. Sal, there is a 30% chance of SCA
level winds during the afternoon/evening hours Mon and Tue,
otherwise SCA conds are not expected thru Fri night.

In the inner waters S of Pt Conception, SCA conditions are not
expected thru Fri night. The possible exception is in western
portions from Santa Cruz Island to the SBA County south coast from
Pt. Conception to Refugio State Beach, where there is a 30%
chance of SCA level winds during the late afternoon thru late
evening hours Tue thru Thu.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning remains in effect until 9 PM PDT
      Thursday for zones 38-343>345-351>353-376>383. (See LAXNPWLOX).
     Heat Advisory in effect from 10 AM this morning to 10 AM PDT
      Tuesday for zones 88-357-358-371-372-375. (See LAXNPWLOX).
     Excessive Heat Watch in effect from Tuesday morning through
      Thursday evening for zones 88-356>358-369>375-548. (See LAXNPWLOX).
     Dense Fog Advisory in effect until 9 AM PDT this morning for
      zones 340-341-346-347-349-350-354-355-362-366>368. (See LAXNPWLOX).
     Red Flag Warning in effect until 6 AM PDT early this morning
      for zones 378-381. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect from 2 PM this afternoon to 3
      AM PDT Thursday for zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Lund/DB
AVIATION...Munroe
MARINE...Munroe/Sirard
SYNOPSIS...Hall

weather.gov/losangeles

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