600
FXUS66 KLOX 102131
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
231 PM PDT Wed Jul 10 2024

Updated Aviation and Marine sections

.SYNOPSIS...10/102 PM.

A long-lasting and extreme heatwave will continue across the
mountains and interior areas through much of the week, as a
strong high pressure system remains anchored over the region. A
high risk of dangerous heat illness exists across the interior
portions of the area. A cooling trend is expected by Friday and
the weekend but temperatures will remain well above normal inland.

&&

.SHORT TERM (TDY-SAT)...10/102 PM.

Synoptically, the area is under a large dome of higher heights
(597 dam) centered along the NV/AZ border and extending over most
of California. This ridge will build slightly (598 dam) and move
further to the east, centering over the UT/AZ border by Friday. Local
heights will fall beginning on Friday as this feature moves away
and drop to about 590 dam, where they will stay through next
Wednesday. The position of the high over the weekend is somewhat
favorable to bring moisture to the area, and models still show
moisture above 500mb on Saturday and Sunday which could lead to
convective activity over the weekend. Still putting this as a
5-10% chance and it is not in the weather grids.

Temperatures remain up several degrees over yesterday as they got
off to a warmer start under mostly clear skies along the south
coast this morning. Issued a Heat Advisory for the downtown LA
area as it should finish a bit over 90 today which is almost 10
degrees above normal.

High pressure aloft will continue to impact the forecast area,
with dangerously hot weather continuing across the majority of the
region through at least Thursday. The Excessive Heat Warning
remains in effect through Saturday for far interior areas
including the Antelope Valley due to forecast temperatures of 106
to 116 degrees. Excessive Heat Warnings remain in place for
Coastal Valleys and Coastal Mountains through Thursday for
temperatures of 98 to 108 degrees expected. This extremely hot
weather puts anyone at risk for heat illness, and it is highly
recommended to limit time outdoors and remain sufficiently
hydrated during this time.

Today and Thursday will be very similar weather-wise. Temperatures
across far interior areas may be slightly higher Thursday compared
to today and will remain 10 to 15 degrees above normal for this
time of year across areas away from the coast. Areas closer to
the beaches will be in the 70s thanks to the marine layer
influence. Expecting similar cloud conditions Thursday.

Today and Thursday the I-5 corridor, western Santa Ynez range,
and southwestern Santa Barbara South Coast will see northwest
winds of 30 to 40 mph. There is less confidence than yesterday
that the Sundowner winds will reach advisory levels tonight, as
the upper level support looks to be weak.

On Friday, temperatures will start cooling by a couple of
degrees across the board, however it will still remain very hot
and warrant the interior Excessive Heat Warnings to continue.
Additionally, temperatures across the coastal valleys and coastal
mountains may still remain high enough that heat advisories will
possibly be needed again. Marine layer clouds may roll further
inland as onshore flow increases by one millibar for the LAX to
DAG gradient on Friday.

Saturday should bring another couple degrees of cooling as some
mid or high clouds could make an appearance, and the High moves
further to our east.

.LONG TERM (SUN-WED)...10/112 PM.

The cooling trend should continue Sunday through Tuesday and
temperatures are expected to fall by 2 to 5 degrees across the
region each day (except in the Antelope Valley which is forecast
to remain around 102 to 105). Some high to mid clouds on Sunday should
also help to keep temps down.

It looks like the convection and dry lightning will stay to our
east on Sunday and Monday, but there is still a 5-10 percent
chance of afternoon convection and dry lightning, mostly likely
just impacting the far eastern San Gabriels if anywhere.

On Tuesday, temperatures look to be very similar to forecast
temperatures on Monday. Highs will actually be near seasonal for
this time of year, if not a few degrees cooler for once.

Wednesday should start similarly to Tuesday, but by later in the
day it looks like a gradual warming trend will begin and drive
temps up a couple of degrees each day through next Saturday.

&&

.AVIATION...10/2129Z.

At 21Z at KLAX, the marine layer was 800 feet deep. The top of
the inversion was at 3000 feet with a temperature of 31 deg C.

High confidence in CAVU TAFs for KPRB, KVNY, KPMD, and KWJF.

Moderate to high confidence in KBUR TAF.

Moderate confidence in remaining TAFs at coastal sites and
coastal valley sites. For these locations, IFR to LIFR cigs with
MVFR to IFR vsbys will return tonight through Thursday morning.
Smoke will further contribute to vsby restrictions, especially at
KSBA. Timing of flight category changes may vary +/- 2-3 hours
from current forecasts. There is a 30% chance for minimum
vsbys/cigs to be off by a category.

KLAX...Moderate confidence in TAF. There is a 30% chance for
vsbys to become IFR tonight and Thursday morning. No significant
east wind component is expected.

KBUR...Moderate to high confidence in TAF. There is a 20% chance
for MVFR vsbys/cigs to occur tonight into Thursday morning.

&&

.MARINE...10/229 PM.

SCA conditions are not expected through this weekend.

Dense fog will continue over the coastal waters for tonight and
Thursday morning. Please reference the Marine Weather Statement
for additional information.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning remains in effect until 9 PM PDT
      Saturday for zones 38-343>345-353-376>379-381>383. (See LAXNPWLOX).
     Excessive Heat Warning remains in effect until 9 PM PDT
      Thursday for zones 88-351-352-356>358-369>375-380-548. (See LAXNPWLOX).
     Heat Advisory in effect until 8 PM PDT this evening for zone
      368. (See LAXNPWLOX).
PZ...NONE.

&&

$$

PUBLIC...jld
AVIATION...Cohen
MARINE...Cohen
SYNOPSIS...MW/Smith

weather.gov/losangeles

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