-- Discussion containing changed information from previous version are highlighted. --
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FXUS66 KLOX 161754 AAA
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1054 AM PDT Sun Jun 16 2024

updated aviation discussion

.SYNOPSIS...16/345 AM.

Warm to hot conditions are expected again today, although it will
be a bit cooler in most areas. More significant cooling is likely
Monday, then minor changes through Wednesday. Temperatures will
then trend upwards by the end of this week. Gusty north to
northwest winds will affect portions of the region, including
southern Santa Barbara County, the Interstate 5 cooridor, Antelope
Valley, and the Central Coast, through at least Monday night.

&&

.SHORT TERM (TDY-TUE)...16/946 AM.

***UPDATE***

Strengthening northwest to north winds across the I-5 corridor in
northwest LA County as well as the Ventura County mountains,
especially tonight, will combine with low relative humidity to
create favorable conditions for rapid spread and intensification
of wildfires. This includes the ongoing Post Fire complex, and a
Red Flag Warning has been issued. Please reference the Fire
Weather section below for additional information.

Smoke from the Post Fire complex will affect a large portion of
LA County and eastern Ventura County and will bring air-quality
impacts to many areas. The forecast has been updated to account
for the addition of smoke. Please reference the Air Quality Alert
Message for additional information.

With increasing upper support over the area in the base of a
deepening cyclone positioned well north of the forecast area, the
strongest winds will become primarily focused to the I-5 corridor
in northwest LA County as well as the northern and southern
Ventura County mountains, in addition to the western Santa Barbara
County South Coast and western Santa Ynez Range. The High Wind
Warning continues for these areas, with wind gusts increasing to
60-70 mph tonight. The latest indications are that there will be a
relative minimum in these winds across the Santa Barbara County
interior mountains, where wind gusts could still reach upwards of
50 mph, and the High Wind Warning has been replaced by a Wind
Advisory. While the Wind Advisory for the Santa Clarita Valley
expires at 11AM PDT this morning, there is an 80% chance that
another Wind Advisory will be issued for tonight into Monday.

A Heat Advisory remains in effect today for southern Santa
Barbara County, where temperatures today will soar well into the
90s away from the immediate coast.

For additional details regarding the forecast, please reference
the discussion sections below.

***From Previous Discussion***

Strong NW-N winds continued across much of southern SBA County,
the mountains from eastern SBA County thru L.A. County, thru the
I-5 Corridor, in the foothills of the Antelope Valley and in the
Santa Clarita Valley. Temperatures were still in the mid 70s to
around 80 in some foothill locations in SBA/VTU/L.A. Counties
early this morning. An eddy circulation has developed across the
inner waters, and low clouds have pushed into southern L.A.
County. Expect clouds to overspread most of the L.A. County coast
this morning and possibly slip into the San Gabriel Valley. N of
Pt Conception, low clouds have developed in southern portions of
the Central Coast and in the Santa Ynez Valley due to upslope
flow against the N slopes of the Santa Ynez Range. Clouds should
clear in most areas by mid morning. There will probably be areas
of smoke from the Post Fire across portions of L.A. County today.

An unseasonably strong and cold upper low will move into and
across Washington state today, then into Idaho and eventually
Montana tonight and Mon. To the south of this upper low, a trough
will sharpen across CA later today and tonight, then it will move
east and flatten Mon. Strong westerly flow aloft will continue
across the region through tonight, then fast west to northwest
broadly cyclonic flow will continue through Tue. At the surface,
N-S gradients will remain strong right through early Tue.

As a result, a long duration strong NW to N wind event will
affect many parts of Southwest California thru at least Mon
night. Winds will likely be strongest this morning, and again late
this afternoon thru late tonight, with gusts to 60 to 65 mph in
the more favored locations. High Wind Warning level winds may be
somewhat less widespread tonight, but they will still likely occur
across southwestern SBA County, the interior mtns of SBA County,
the Ventura County mtns, thru the I-5 Corridor, and in the
western foothills of the Antelope Valley. While winds should drop
below High Wind Warning levels in southeastern SBA County this
morning, winds will likely remain at advisory level at times
through late tonight, and possibly again late Mon and Mon night.

Advisory level NW winds will likely continue in the Antelope
Valley thru late tonight, and will likely redevelop this
afternoon/evening on the Central Coast. There will likely be
another round of gusty NW winds in the Santa Clarita Valley
tonight after a lull later this morning, and wind advisories may
have to be extended there thru at least late tonight.

With falling heights and some cooling thru the atmosphere, max
temps today should be a few degrees lower than they were Sat in
most areas. However, they should still be somewhat above normal.
Temps will be very tricky across southern SBA County, as warm
downslope northerly winds will be battling with the cooler marine
air pushed northward by the eddy circulation in the inner waters.
It does appear that there will be significant cooling in
southeastern SBA County today, especially near the coast from the
city of Santa Barbara eastward. However, max temps may still jump
again late this afternoon/evening, and since it remained fairly
warm overnight, the chance of heat stress may be a bit higher
than the max temps might suggest. After some consideration, have
decided to leave the Heat Advisory as is for southern SBA County
especially since it includes the foothills which will likely be
very warm again today.

Low clouds and fog will likely be a bit more widespread tonight/Mon
morning across coastal sections of L.A. County, and clouds will
likely push into the San Gabriel Valley and possibly portions of
the San Fernando Valley. By late tonight, some stratus could push
into coastal sections of VTU County. Once again, expect some night
thru morning low clouds/fog in southern portions of the Central
Coast and in the Santa Ynez Valley. Expect skies to clear in most
areas by late Mon morning. Height falls and cooling at 850 mb and
950 mb should bring several degrees of cooling to most areas Mon.

There will be another spike in the NW winds late Mon into Mon
night, but expect winds to be mostly in the Wind Advisory level
range. The low level flow will try to turn more northeasterly Tue
morning as pressure gradients between KLAX and KDAG turn weakly
offshore. This should bring an end to the gusty NW winds in most
areas late Mon night, but some gusty NE winds are possible in the
mtns of L.A. County Tue morning. With the increased NE low level
flow shown by the latest models, there may be somewhat of a
reduction in night thru morning low clouds and fog across L.A.
County Mon night/Tue morning. Max temps may actually rise a bit on
Tue as heights rise slightly and both N-S and W-E gradients will
be offshore to start the day.

.LONG TERM (WED-SAT)...16/525 AM.

There continues to be good agreement amongst the operational
runs of the GFS and the EC, showing another trough developing
along the West Coast Wed, sharpening in place Wed night and Thu,
then beginning to flatten out and move east Fri. Heights will
rise late Fri and Sat as an upper high in Texas and northern
Mexico expands northwestward toward the region.

This pattern should bring areas of night thru morning low clouds
and fog to most coastal and some valley areas Wed thru Fri, with a
possible decrease in low clouds coverage in the valleys by Fri or
Sat as rising heights suppress the depth of the marine layer.
N-S gradients may still be sufficient to produce gusty winds
across SBA County during the late afternoon and evening hours
Wed and Thu, but do not expect winds to be as strong as they
have been recently.

Do not expect too much change in max temps Wed and Thu, remaining
generally within a few degrees of normal, then expect at least a
few degrees of warming both Fri and Sat, especially across the
interior. Max temps may reach or exceed 100 degrees in the
Antelope Valley, and possibly the interior valleys of SLO County
by Fri and Sat.

&&

.AVIATION...
-- Changed Discussion --
16/1753Z.

At 17Z at KLAX, the marine layer was 1900 feet deep. The top of
the inversion was at 3400 ft with a temperature of 21 deg C.

Overall, moderate to high confidence in the 18Z TAF package. For
most sites, VFR conds are anticipated through the period. However
for KOXR, KCMA, KSMO, KLAX, and KLGB, CIG restrictions to IFR/MVFR
will be possible sometime between 05Z-18Z. The timing of the
onset and any dissipation of the low clouds may be off +/- an hour
or two.

Gusty north winds will continue through the period. Light
turbulence and LLWS will be likely across the mountains and
foothills.

KLAX...Moderate confidence in the 18Z TAF. VFR conds with a smoke
layer aloft will prevail into this evening. For tonight, moderate
confidence in return of IFR/MVFR CIGs with a window of +/- 2
hours for timing of return. The cigs should scatter out around 21Z
Mon. No significant easterly wind component is expected.

KBUR...High confidence in the 18Z TAF as CAVU conditions are
expected through the period. There is a 20-30% chance for smoke to
produce some MVFR VSBYs and/or BKN040-060 conditions at any time
during the fcst period.
-- End Changed Discussion --

&&

.MARINE...16/804 AM.

For the Outer Waters, high confidence in current forecast. Winds
are expected to remain at Gale force levels through Monday. So,
GALE WARNINGS will remain in place during this time (with a 20%
chance of Storm force winds through Sunday night). Seas will peak
in the 12 to 15 foot range through Monday. For Tuesday through
Thursday, winds will subside, but remain at Small Craft Advisory
(SCA) levels while seas drop below 10 feet.

For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. There is a 60-80% chance of Gale
force winds this afternoon through tonight and a GALE WARNING
remains in effect. Seas will peak between 10 to 13 foot through
tonight. For Monday through Wednesday, there is a 60-80% chance of
SCA level winds. On Thursday, winds and seas should remain below
SCA levels.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. For the western Santa Barbara
Channel, high confidence in Gale Force Winds this afternoon
through tonight and a GALE WARNING remains in effect. The winds
will be strongest from mid channel and westward. For Monday
through Thursday, there will be a 60-80% chance of SCA level winds
across the western half of the Santa Barbara Channel. Elsewhere
across the southern Inner Waters, there is a 20-30% chance of SCA
level winds this afternoon with high confidence in winds and seas
below SCA levels Monday through Thursday.

Across all of the coastal waters, steep and dangerous seas can be
expected through early this week.

&&

.BEACHES...16/806 AM.

Short-period wind waves, due to gale force winds over the nearby
coastal waters, will generate significant surf conditions along
the local beaches today through Monday. High surf of 4 to 7 feet
will impact the beaches of Ventura county. For the beaches along
the Central Coast as well as Los Angeles county, elevated surf
conditions will continue through Monday. Along with the surf
conditions, dangerous rip currents can be expected into early this
week.

&&

.FIRE WEATHER...16/920 AM.

GOES-16 satellite imagery indicates that the ongoing Post Fire
complex in the vicinity of the I-5 corridor in northwest LA
County and adjacent northern Ventura County continues to grow in
size and intensity. Weather conditions will become increasingly
conducive for further growth and intensification of this complex,
especially tonight, and a Red Flag Warning has been issued for the
I-5 corridor in northwest LA County and the Ventura County
Mountains. For these areas, the latest data suggest that northwest
to north winds will gust to 45 to 55 mph today, increase to 60 to
70 mph range tonight, and then gradually decrease to 30 to 50 mph
through the day Monday. Sustained wind speeds will generally be
in the 20 to 40 mph range. These strong winds, with the notable
uptick tonight, will be caused by increasing upper support
overspreading Southern California in the base of a deepening
cyclone centered well north of the area. The upper pattern will
also bring an influx of abundant dry air into the area, and
minimum afternoon relative humidity values are expected to range
from 15 to 25 percent, locally as low as 10 percent in downslope-
flow favored areas -- with only poor to moderate overnight
recovery to around 25 to 40 percent tonight. While live fuel
moisture readings are still quite high, ample fuel loading of
dead fuels is likely contributing to the extreme fire behavior
with the Post Fire complex, and increasingly favorable
meteorological conditions are expected to foster further growth
and intensification of this fire complex or any other fires
developing in the Red Flag Warning area. The Red Flag Warning is
currently set to expire at 3PM PDT Monday, however, conditions
will be re-evaluated for possible extension of the Warning in
subsequent forecasts, given the potential for gusty winds to
continue into Monday night.

Elsewhere across the region, gusty northwest to north winds are
expected to continue through Monday, peaking in intensity tonight
with a secondary peak Sunday night into early Monday. Wind gusts
of 30 to 50 mph will be common at times through the period for the
Central Coast, mountains of Santa Barbara, Ventura and northwest
LA County as well as the Antelope Valley (strongest in the
mountains and deserts). Isolated gusts to 65 mph will be likely in
the strongest periods of wind across western the Santa Ynez Range
and adjacent western Santa Barbara County South Coast, primarily
in the evening and overnight hours in conjunction with Sundowner
wind enhancements and nocturnal drainage processes. Meanwhile, a
warm and dry air mass will remain in place, with widespread 8 to
15 percent humidities across the interior today, and 12 to 20
percent on Monday. Poor overnight recoveries in the foothills are
also expected. The warm and dry air will continue to descend into
some coastal foothills on Sunday, including portions of southern
Santa Barbara County. The combination of gusty winds, warm
temperatures, and low humidities will continue to bring elevated
to brief critical fire weather conditions across southern Santa
Barbara county through Sunday night, and all interior areas
through Monday. There is an increased risk for fast-growing grass
fires over much of the area, that could transition into wildfires
where the fuel beds are most abundant and dry.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CA...Beach Hazards Statement in effect through Monday evening for
      zones 87-340-346-362-366. (See LAXCFWLOX).
     Wind Advisory remains in effect until 11 AM PDT this morning
      for zone 88. (See LAXNPWLOX).
     Wind Advisory remains in effect until 8 PM PDT this evening
      for zones 340-341-346-347. (See LAXNPWLOX).
     High Wind Warning remains in effect until 11 AM PDT Monday
      for zones 349-351-376>378-381. (See LAXNPWLOX).
     Heat Advisory remains in effect until 8 PM PDT this evening
      for zones 349>352. (See LAXNPWLOX).
     High Wind Warning remains in effect until 11 AM PDT this
      morning for zones 350-352. (See LAXNPWLOX).
     Wind Advisory in effect until 11 AM PDT Monday for zone 353.
      (See LAXNPWLOX).
     High Surf Advisory in effect until 7 PM PDT Monday for zone
      354. (See LAXCFWLOX).
     Wind Advisory remains in effect until 3 AM PDT Monday for
      zones 356-383. (See LAXNPWLOX).
     Red Flag Warning in effect until 3 PM PDT Monday for zones
      376>378. (See LAXRFWLOX).
PZ...Gale Warning in effect until 2 AM PDT Monday for zones
      645-650. (See LAXMWWLOX).
     Gale Warning in effect until 7 PM PDT Monday for zones
      670-673-676. (See LAXMWWLOX).
-- End Changed Discussion --

&&

$$

PUBLIC...Cohen/DB
AVIATION...Sirard
MARINE...RAT/Sirard
BEACHES...RAT/Cohen/Sirard
FIRE...Cohen/Gomberg
SYNOPSIS...DB

weather.gov/losangeles

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