740
FXUS66 KLOX 111044
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
344 AM PDT Thu Jul 11 2024

.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)...11/329 AM.

The marine layer is about 900 ft deep. The E/W gradient is near
neutral while there is weak onshore flow to the north. Low clouds
cover all of the coastal sections. Burn off will be similar to
Wednesday. There are some high clouds drifting in from the SE and
skies may be partly cloudy at times.

Heat is still the #1 issue. 596 dam hgts are over the area
extending from a very warm 598 dam upper high centered over
eastern NV. Excessive Heat Warnings for the valleys (max temps 95
to 106 | 6 to 12 degrees above normal) last through this evening.
The Excessive Heat Warnings for the Mtns and Interior (max temps
110 to 110 | 8 to 12 degrees above normal) continue to today and
beyond.

Look for a similar low cloud pattern tonight with an early low
cloud arrival for the immediate coasts north of Malibu. It will
be warm again for the foothills, lower mtns and deserts, with lows
in the 70s to around 80 expected.

Slight hgt falls will occur Friday as the upper high moves to the
east. The onshore flow will increase a little as well. More
importantly there will be an increase in mid level clouds and
moisture as the new position of the high shuttles some monsoon
moisture into the area. These factors will combine to bring 1 to
2 degrees of cooling to the area. Enough to preclude any heat
products for the vlys, but not enough to prevent bring
temperatures out of Excessive Heat Warning criteria for the Mtns
and Interior. The one possible fly in the ointment is the mid
level clouds which if they come in thicker than fcst could lead to
more dramatic cooling. The convective parameters are still too
low to mention showers or TSTMs but there will likely some build
ups over the LA and VTA mtns.

The upper high moves to near the 4 corners region on Saturday.
This puts it into a good location for some monsoon flow and aside
from the relentless coastal low clouds in the morning skies will
be partly cloudy. There is also enough afternoon instability to
bring a slight chc of TSTMs to the eastern LA mtns and the
Antelope Vly.

More cooling is forecast for the interior due to the increased
cloud cover. The heat warning remains in effect through the
evening, but if the clouds are thick enough it may be cancelled
early this will be the short range problem of the next two days.

.LONG TERM (SUN-WED)...11/343 AM.

Deterministic and ensemble means agree that a trof will push
closer to the west coast Sunday and will linger there through
Tuesday. At the same time the onshore flow will increase. The
marine layer will deepen and will push further inland. Max temps
will fall each day and by Tuesday most areas will be 2 to 4
degrees blo normal.

The upper trof will nudge the monsoon moisture back to the east
and the afternoon convection threat will fall below 10 percent.

The strong onshore push in the afternoon will keep some west
facing beaches cloudy through most of or even all of the
afternoon. In addition there will be gusty near advisory level
winds across the interior.

On Wednesday it is likely that the upper high will push westward
again and kick off a warming trend that may extend into the
weekend.

&&

.AVIATION...11/0601Z.

At 0505Z at KLAX, the marine layer was near 900 feet deep. The
top of the inversion was at 2500 feet with a temperature of 32 C.

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

Good confidence in KBUR TAF, with a 15 percent chance of IFR CIGs
for the overnight period.

Moderate confidence in the remaining TAF sites. Timing of flight
category changes may vary +/- 2 hours from current fcst. There is
a 30% chance that flight cat to be off by one category.

KLAX...Moderate confidence in TAF. The arrival time of IFR conds
may be delayed by up to 3 hours. There is a 10 percent chance of
3/4SM BR OVC003 conds 11Z to 15Z. No significant east wind
component is expected.

KBUR...Good confidence in TAF. There is a 15% chance of 1/2sm fg
VV002 conds 13Z-15Z.

&&

.MARINE...10/752 PM.

SCA conditions are not expected through Monday night.

Dense fog will continue over the coastal waters tonight into
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 this
      evening for zones 88-351-352-356>358-369>375-380-548. (See LAXNPWLOX).
PZ...NONE.

&&

$$

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

weather.gov/losangeles

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