071
FXUS66 KLOX 051328
AFDLOX

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

.SYNOPSIS...05/443 AM.

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 this 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)...05/440 AM.

Unsurprisingly, hot weather continues through the extended period
due to the high pressure aloft hanging out to the north and east
of the region. The onshore flow starts weakening again on
Monday resulting in a few degrees of warming both Monday and
Tuesday across the region, except the deserts and mountains which
will change little if at all due to the stationary high. Then,
conditions are expected to be very similar Tuesday through
Thursday. The deserts and far interior areas of SLO County 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 up to 4-8 degrees above normal
all week.

&&

.AVIATION...05/1328Z.

At 11Z at KLAX, the marine layer was 700 feet deep. The top of
the inversion was at 3000 feet with a temperature of 32 deg
Celsius.

Low clouds were affecting coastal areas of Ventura and L.A.
Counties, the Central Coast, and western portions of the Santa
Ynez Valley. Conds were mostly LIFR to VLIFR, except locally IFR
in L.A. County. Skies should clear in most areas by mid to late
morning, but could linger at the beaches into the afternoon.
There will be some MVFR to even local IFR vsbys in the valleys
through mid morning in haze.

Expect similar low cloud coverage tonight, with stratus mainly
affecting coastal sections of L.A. and VTU Counties, and possibly
the Central Coast. Conds will be mostly VLIFR to LIFR.

KLAX...Moderate confidence in the 12Z TAF. IFR to LIFR cigs are
expected to arrive by 14Z. There is a 20% chance that skies will
remain clear. There is a 20-30% chance that, if cigs arrive as
expected, they will linger until 18Z. Tonight, there is a 20%
chance that IFR cigs will arrive as early as 06Z. There is a 30%
chance of an east wind component of 7-8 kt from 10Z-17Z Sat.

KBUR...High confidence in 12Z TAF with VFR conds after MVFR to IFR
vsbys in HZ improve by mid morning.

&&

.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).
     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...DB
MARINE...DB
SYNOPSIS...MW/KL/CS

weather.gov/losangeles

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