685
FXUS66 KLOX 280330
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
830 PM PDT Thu Aug 27 2026

.SYNOPSIS...27/217 PM.

Hot and muggy conditions will continue through Friday with a high
risk for heat-related illness. Scattered showers and
thunderstorms are possible through Friday, with risks of
lightning, fire starts, and erratic winds. Temperature and
moisture relief will start over the weekend, but will increase
again starting Tuesday, with a chance for showers and convection.

&&

.SHORT TERM (THU-SUN)...27/830 PM.

***UPDATE***

 Highs today came in about 5 to 12 degrees colder today for Ventura
and Los Angeles Counties, likely due to some additional clouds
and some sporadic showers. Pressure gradients were pretty weak,
with very minimal onshore flow. Further north, the difference was
far more significant, with areas away from the coast seeing a
large 15 to 25 degrees drop. More showers along with much thicker
clouds likely played a role. Looking at temperatures for tomorrow,
expecting clouds to break up in the afternoon hours, so thinking
things will be warmer than today, and temperatures were decreased
2 to 5 degrees from Santa Barbara to San Luis Obispo County to
account for the ongoing shower/thunderstorm chances and additional
clouds.

This evening, showers have grown isolated but chances are ongoing
into Friday. Gusty sundowner winds have developed as well, and
guidance failed to pick up on a SBA-BFL offshore gradient of 5
mb, helping to drive these winds. A short-duration wind advisory
was issued for the Santa Ynez Range and southwestern Santa Barbara
Coast to cover wind gusts up to 45 mph, although this may need to
be canceled early if winds fail to sustain/increase their speeds.
The current forecast looks on track, with no other significant
changes.

***From Previous Discussion***

What a difficult forecast thanks to the remnants of Tropical Storm
Iselle (ee-SELL) which are now upon us. There are so many
potential impacts and outcomes over the next 36 hours.

Lets start off with the shower and thunderstorm piece. For the
rest of today, scattered light showers will continue to impact
portions of all four of our counties. Any rain amounts should
stay under 0.10 inches. We had 8 lightning strikes around
Vandenberg this morning, but not much since then. There is still a
small chance anywhere today, with the highest chances on the
Central Coast and any of our mountains and deserts. All
indications suggest a shift northward and decrease in activity
overall tonight, but with the moisture still in place, cannot
completely rule out an isolated shower or two. For tomorrow, a
trough to the northwest will interact with this tropical moisture
and enhance the chance for showers and thunderstorms, mainly for
areas north of Santa Ynez. As a possible glimpse into the future,
this interaction is currently taking place about 400 miles
southwest of Point Conception. The current IR satellite over
there shows rapidly cooling cloud tops (an indicator of
convection) with the lightning-cast algorithm showing a 50%
chance of thunderstorms. This all adds up to a 10-30% chance of
showers and thunderstorms, with the highest chances over San Luis
Obispo County, decreasing to the south. The main threat will
continue to be cloud-to-ground lightning and erratic winds, which
pose a significant risk for fire starts and growth. The risk for
isolated heavy rain and flooding is not zero but it is low. The
moisture is on track to exit the region overnight on Friday and be
gone by Saturday.

Next up...the temperature bit. The clouds wreaked havoc on the
temperatures today. Much of Los Angeles and Ventura Counties are
down 5-10 degrees compared to yesterday, and much of Santa Barbara
and San Luis Obispo Counties are down 15-25 degrees (except for
5-10 degrees of warming over SW Santa Barbara County). Despite
the numeric cool down, most will agree that it still feels hot as
dewpoints are around 70 degrees for much of our region, which is
similar to Florida right now. With the new tropical airmass,
overnight lows last night were sweltering. While some areas will
be different, cannot see a reason for the majority of the region
to experience something similar again tonight. Daytime
temperatures on Friday are a muddled mess. Fairly confidence that
Los Angeles and Ventura Counties will see less cloud cover and
therefore should be noticeably warmer than today. For Santa
Barbara and San Luis Obispo County, the trends could be up 10 or
down 10 depending on how that moisture plume and any convection
sets up. Because of all of these complexities and uncertainties,
we will NOT be changing any of the Heat Warnings or Advisories
today, but might need to make some adjustments tomorrow. At this
point, the chance of extending any heat seeing any need to extend
anything beyond tomorrow.

That gets us through Friday Night. For the weekend, the airmass
will dry out and cool down, especially by Sunday when temperatures
will drop enough to cross under normal. The marine layer clouds
will likely make a return, but exact coverage is always a tough
call. Sundowner winds will peak Saturday Night with a Wind
Advisory more favorable than not.

.LONG TERM (MON-THU)...27/215 PM.

Monday looks pretty benign with below normal temperatures, coastal
low clouds, and typically breezy mountain winds. After
that...anything goes. A disturbance currently forming off the
Baja coast will likely form into a Tropical Storm as it moves
toward the west to northwest. Another trough will likely form to
the north and interact with that tropical moisture in the Tuesday
through Thursday timeframe. About half of the projections result
in some of this moisture streaming over southwest California,
with about 10 percent of the solutions resulting in rain. About 5%
of the earlier projections showed heavy rain with the bulk of the
moisture moving over, but that signal is largely gone in the
latest projections. With all that stated, the most likely outcome
is for some increased mugginess and warmer conditions and that is
about it, with intel about the rest of the risks in a clear wait
and see holding pattern.

&&

.AVIATION...27/2332Z.

At 2238Z at KLAX, the marine layer was 600 feet deep. The top of
the inversion was 1600 feet with a temperature of 32 C.

Overall, moderate confidence in 00Z TAF Package. For most of
the period expecting BKN/OVC080-150 with isolated to scattered
light showers in the area through 28/06Z with a 5-10% chance of
a lightning strike at any airfield. Showers could linger a bit
later for KPRB and KSBP but most guidance keeps activity just
offshore.

KLAX...Moderate confidence in TAF. A light shower or two may
occur through 28/06Z, otherwise BKN/OVC deck above 10KFT thru at
least 28/18Z. Any east wind component is expected to remain below
7 kts.

KBUR...Moderate confidence in AF. BKN/OVC deck above 10KFT thru at
least 28/18Z. A shower or two is possible through 28/09Z. 5% chc
of a lightning strike.

&&

.MARINE...27/744 PM.

Through this weekend, high confidence in small craft advisory
(SCA) level winds across the outer waters with short-period
choppy seas. These hazardous conditions will reach into the
nearshore waters along the Central and into the Santa Barbara
Channel at times (especially afternoon/eve). Local gusts may
approach 35 kt near Point Conception Saturday evening.

Isolated to scattered showers are expected to continue across the
coastal waters mainly north and west of Point Conception. There
is a 10% chance of thunderstorms which could bring the threat
of erratic winds, localized rough seas and cloud-to-surface
lightning.

For next week, most waters are likely to fall below SCA levels
Monday and Tuesday. Increasing chances for SCA conditions later
in the week but signal isn`t strong, moderate at best.

&&

.FIRE WEATHER...27/310 PM.

An extended period of very hot and dry conditions will bring widespread
elevated to brief critical fire weather conditions away from the immediate
coast through this weekend. Triple digit temperatures, very deep mixing
heights, locally gusty winds, and low humidities (focused Friday) with
fuels approaching critical levels will bring the highest risk of large
plume dominated fires with rapid spread in the interior mountains and
adjacent foothills, as well as the Cuyama Valley, resulting in the Red
Flag Warning issuance through Friday. Gustiest winds will likely occur
this evening across interior mountain areas. Conditions will generally
improve this weekend and into early next week, especially on the coastal
side of the mountains. However, increasing onshore flow will still bring
elevated to locally brief critical conditions to far interior areas.

Moderate Sundowner winds with hot and dry conditions will likely bring
elevated to brief critical fire weather conditions across southern Santa
Barbara county through Sunday night, likely peaking Saturday with winds
15 to 30 mph with gusts 30 to 45 mph (locally up to 55 mph near Gaviota
and Refugio).

Subtropical moisture associated with former Tropical Storm Iselle will
bring a 15 to 25 percent chance of showers and thunderstorms over the area
through Friday with the potential for dry lightning. Highest chances
exist Friday over San Luis Obispo County, thus a Red Flag Warning is in
effect.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Extreme Heat Warning in effect until 8 PM PDT Friday for
      zones 38-87-88-349>358-362-366>376-378>383-548. (See LAXNPWLOX).
     Beach Hazards Statement in effect until 11 PM PDT this
      evening for zones 87-354-362-366. (See LAXCFWLOX).
     Heat Advisory in effect until 8 PM PDT Friday for zones
      341>345-347-348. (See LAXNPWLOX).
     Wind Advisory in effect until 1 AM PDT Friday for zones
      349-351-352. (See LAXNPWLOX).
     Red Flag Warning in effect from 5 AM to 3 PM PDT Friday for
      zones 340>345. (See LAXRFWLOX).
     Red Flag Warning in effect until 3 PM PDT Friday for zones
      353-375>380. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect from 3 PM Friday to 3 AM PDT
      Saturday for zones 645-650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 PM PDT Saturday for
      zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Phillips/RK
AVIATION...Black
MARINE...Black
FIRE...Lewis
SYNOPSIS...RK

weather.gov/losangeles

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