491
FXUS66 KLOX 051132
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
432 AM PDT Fri Jul 5 2024

.SYNOPSIS...04/739 PM.

A significant heatwave will affect the region this week and will
continue through much of next week, with dangerously hot
temperatures across much of the area. High temperatures will reach
95 to 105 degrees in many areas away from the coast, and upwards
of 105 to 115 across interior valleys and foothills, including the
Antelope Valley. Patchy night to morning dense fog will develop
near the coast through at least Friday morning.

&&

.SHORT TERM (TDY-SUN)...05/431 AM.

Well, today is the day - the hottest day of the prolonged period
of dangerously hot weather. Make sure to limit time outdoors in
the sun and stay hydrated to avoid any heat illness.

Some low clouds and fog were hanging out along the coasts early
this morning, though very patchy in nature. Onshore pressure
gradients between KLAX and KDAG were weakening, while N-S
gradients were becoming increasingly offshore. Therefore, the
marine layer clouds are expected to burn off rather quickly this
morning. Temps at 950 mb are expected to rise quite a bit today
due to all of this. This will allow for plenty of heating -up to
20 degrees compared to yesterday`s high temperatures, and 15 to 20
degrees above normal for this time of year. As a result, today
has the best chance for several locations to break daily high
temperature records.

Saturday`s maximum temperatures will be similar to today`s,
though a few degrees cooler at the coasts and coastal valleys due
to increasing onshore trends through the weekend. Exact
temperatures at the coastal locations on Saturday will depend on
when the increasing onshore trends start up, leading to less
confidence in the heat advisories for coastal areas on Saturday.
Even less confidence in the advisories on Sunday as temperatures
in the mid 70s to mid 80s would be below advisory criteria. While
the onshore flow will reach interior areas on Sunday,
temperatures will still be at or above 110 in the deserts and far
interior valleys of SLO County, and above 100 degrees in the
warmer locations in the L.A./VTU valleys. Therefore the Excessive
heat warnings will likely still be needed across those locations.
The increase in onshore winds there in the afternoon, particularly
across the interior mountains and Antelope Valley, will increase
the fire risk in those areas.

.LONG TERM (MON-THU)...04/209 PM.

The overall pattern next week remains quite hot across the
interior and certainly well above normal closer to the coast.
After Sunday`s onshore flow increase, models have been pretty
consistent indicating lighter, though still present, onshore flow
the rest of next week. Meanwhile, the upper high really doesn`t
move or weaken very much. As a result, interior areas will
continue to scorch with highs near or above 110 and warmer
coastal valley highs will reach around 105 each day. Lower
confidence with coastal temperatures due to the uncertainty with
the marine layer and possible eddy development over the southern
coastal waters, but highs there should be at least 4-8 degrees
above normal all week.

&&

.AVIATION...05/0207Z.

At 00Z at KLAX, the marine layer was 800 feet deep. The top of
the inversion was at 4000 feet with a temperature of 31 deg
Celsius.

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

Expect somewhat less low cloud coverage tonight, mainly affecting
coastal sections of L.A. and VTU Counties, and possibly the
Central Coast. Most likely cigs will be IFR/LIFR. There is a 40%
chance of VLIFR at coastal sites late tonight and early Fri. From
04Z-09Z this evening, there may be areas of MVFR vsbys due to
smoke and haze from holiday fireworks celebrations.

KLAX...Moderate confidence in the 00Z TAF. Cigs may arrive as
early as 03Z, and as late as 09Z. There is a 50% chance of VLIFR
conds 09Z-14Z Fri.

KBUR...High confidence in the 00Z TAF with VFR conds thru the
period, except there is a 30% chance of MVFR vsbys due to smoke
and haze from 05Z-09Z.

&&

.MARINE...05/423 AM.

In the Outer Waters, Small Craft Advisory (SCA) level winds will
continue in the southern zones (PZZ673/PZZ676) thru Sat morning.
In the northern zone (PZZ670), SCA conds are likely (70% chance)
this afternoon thru tonight. For the most part, expect winds to
remain below SCA levels Sat afternoon thru Tue night. However,
there is a 30% chance of SCA level NW winds in the far outer
waters and from near Pt. Conception to NW of San Nicolas Island,
especially during the late afternoon thru late evening hours.

For the Inner Waters N of Pt. Sal, SCA conds are likely (70% chance)
this afternoon/eve. There is a 30% chance of SCA level winds Sat
afternoon/eve. SCA conds are not expected Sat night thru Tue night.

For the Inner Waters south of Pt. Conception, there is a 40%
chance of SCA conds late this afternoon and evening in western
portions of the Santa Barbara Channel, mainly from Santa Cruz
Island to the SBA County south coast from Pt. Conception to
Gaviota to Refugio State Beach. Otherwise, conds will be below SCA
levels for the southern inner waters thru Tue night.

Areas of dense fog will affect the coastal waters this morning.
Please reference the Marine Weather Statement for additional
information.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning remains in effect until 6 PM PDT
      Wednesday for zones 38-343>345-353-376>379-381>383. (See LAXNPWLOX).
     Excessive Heat Warning remains in effect until 6 PM PDT
      Monday for zones 88-342-348-351-352-356>358-369>375-380. (See LAXNPWLOX).
     Heat Advisory remains in effect until 6 PM PDT Sunday for
      zones 341-347-355-368-548. (See LAXNPWLOX).
     Excessive Heat Warning remains in effect until 6 PM PDT
      Saturday for zones 349-350. (See LAXNPWLOX).
     Wind Advisory in effect until 5 AM PDT early this morning for
      zones 349-351. (See LAXNPWLOX).
     Beach Hazards Statement in effect through Sunday evening for
      zones 354-362-366. (See LAXCFWLOX).
     Red Flag Warning in effect from 10 AM this morning to 6 AM
      PDT Saturday for zones 342>345. (See LAXRFWLOX).
     Red Flag Warning in effect until 6 AM PDT Saturday for zones
      349-351>353-376>378-381. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 9
      PM PDT this evening for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect from 3 PM this afternoon to 3
      AM PDT Saturday for zone 670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 AM PDT Saturday for
      zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Lund/DB
AVIATION...Phillips/Sirard
MARINE...DB
SYNOPSIS...MW/KL/CS

weather.gov/losangeles

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