701
FXUS66 KLOX 041801 AAA
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1101 AM PDT Thu Jul 4 2024

updated aviation discussion

.SYNOPSIS...04/912 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 at least Friday morning.

&&

.SHORT TERM (TDY-SAT)...04/933 AM.

***UPDATE***

Low clouds and fog developed again overnight but remains confined
to coastal areas despite the marine layer depth rising to around
1500 feet. Gradients to the east are actually trending weakly
onshore so with this and the deeper marine layer it`s not
surprising that temperatures across many coast and valleys are
starting off a few degrees cooler. Strong high pressure aloft is
preventing any of those influences from reaching the interior and
temperatures there are running 3 to 6 warmer. On the other hand,
gradients to the north are starting to turn offshore. Given the
current situation with the stratus and gradients it`s possible
that temperatures on the coastal side of the mountains today will
be little changed from yesterday or possibly even slightly cooler.
However, those areas influenced by northerly flow, especially
southern Santa Barbara County and parts of the Central Coast,
should trend slightly warmer.

In any case, all signs continue to point to significant warming in
all areas Friday, with highs in the warmer coastal valleys around
or slightly higher than 110 and even some inland coastal areas in
the 90s, especially Central Coast and southern SB County.

***From Previous Discussion***

An extended period of dangerously hot weather will continue across
much of the region into early next week. Not only will high
temperatures be dangerously high, but overnight temperatures will
remain elevated and limit any relief, especially for areas away
from the coast. This will be a time to limit exposure to the sun
(maybe even stay indoors) and make sure to stay hydrated.

The hot weather is a result of high pressure aloft continuing to
creep toward the West Coast and through Central California through
the weekend. Due to the high pressure, the marine layer influence
will be very shallow and remain limited to the coast through the
weekend allowing inland areas to warm up. However, there is a
small chance that clouds will linger at the beaches through the
day today and Saturday, but looks like it will clear out on Friday
due to weak northerly flow and offshore trends.

High temperatures today will increase a few degrees compared to
yesterday, but Friday is looking to have the biggest jump in high
temps with an increase of 5-15 degrees. The Santa Barbara South
Coast will warm 20 degrees due to northerly sundowner flow, except
lower at the immediate coast where a marine influence will most
likely prevail. Warmer coastal valleys will push close to 110 and
inland coastal areas in the 80s to low 90s. Deserts and other far
interior areas will be approaching or even locally exceeding 115.
These high temperatures will be up to 20 degrees above normal for
this time of year, and many daily record high temperatures may be
broken on Friday.

While Friday will be the hottest day with Saturday not far behind,
the duration of this event will likely produce an unprecedented
stretch of high temperatures over 110 degrees for the Deserts and
interior areas. The record for consecutive days at or above 110 is
three for Palmdale and Lancaster and five for Paso Robles. The
desert streak will almost certainly be crushed with the current
forecast showing highs over 110 for the next seven days.

.LONG TERM (SUN-WED)...04/501 AM.

As previously mentioned, the dangerously hot weather will
continue into next week with the upper level high pressure
persisting just to the north and east of the forecast area through
Wednesday. Temperatures will remain extremely high during that
time, but a weak trough will start to push into the region after
Wednesday causing coasts/coastal valleys to start to see slight
cooling (though still 5-10 degrees above normal) due to increasing
onshore flow. The onshore push will likely cause night through
morning clouds to expand further inland past the coasts,
contributing to the cooling. While the deserts may not see any
cooling, increasing winds with the onshore push may reach the
interior area, increasing fire danger there with the continued
extreme heat and hot and dry air mass.

&&

.AVIATION...04/1800Z.

At 17Z at KLAX, the marine layer was 1200 feet deep. The top of
the inversion was at 4100 feet with a temperature of 30 deg
Celsius.

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

Low clouds and IFR conds should clear from the coastal airfields S
of Point Conception by 19Z. Expect somewhat less low cloud
coverage tonight, mainly affecting coastal sections of L.A. and
VTU Counties, and possibly the Central Coast. Conds will be mostly
LIFR to IFR, except for a 50% chance of VLIFR at KLAX and KLGB
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 18Z TAF. There is a 30% chance
that cigs will linger until 19Z. There is a 30% chance of MVFR
vsbys due to smoke and haze from 04Z-09Z. There is a 60% chance
that IFR cigs will move into the airfield this evening around
03Z-04Z. There is a 50% chance of VLIFR conds 11Z-15Z Fri.

KBUR...High confidence in the 18Z 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...04/820 AM.

In the Outer Waters, Small Craft Advisory (SCA) level winds will
develop in the southern zones (PZZ673/PZZ676) this afternoon, with
SCA winds continuing into Saturday morning. In the northern zone
(PZZ670), there is a 40% chance of SCA winds this afternoon/eve,
with SCA level winds expected Fri afternoon thru late Fri night.
There is a 30% chance of SCA level NW winds Sat afternoon/eve. SCA
conds are not expected Sat night thru Mon night.

For the Inner Waters north of Pt. Sal, SCA conditions are not
expected thru Mon night, except there is a 40% chance of SCA
winds Fri afternoon/eve.

For the Inner Waters south of Pt. Conception, SCA winds are likely
during the late afternoon thru late night hours today and Fri in
western portions of the Santa Barbara Channel. The area with the
greatest threat of SCA level winds is from Santa Cruz Island to
the SBA County south coast from Pt. Conception to Gaviota to
Refugio State Beach. Within this area, there is a 10-15% chance
of local Gale Force wind gusts just offshore from the immediate
coast late this afternoon thru late tonight. Otherwise, conds will
be below SCA levels for the southern inner waters through Mon
night.

Areas of dense fog is expected to affect the coastal waters this
morning, with patchy dense fog for tonight and Fri morning.
Please reference the Marine Weather Statement for additional
information.

&&

.BEACHES...04/501 AM.

A southerly swell front will overspread the Southern California
coastal waters today into Friday, followed by 15-17-second
southerly swell persisting from late this week into the weekend.
While surf is not expected to be particularly high, surf heights
upwards of around 5 feet are anticipated at beaches exposed to
southerly swell -- especially the LA and Ventura County beaches.
Moreover, significant wave energy with the long-period swell will
combine with the elevated surf to create dangerous conditions at
area beaches, with powerful and dangerous rip currents expected.
This is especially the case for the beaches of LA and Ventura
Counties. A Beach Hazards Statement is in effect from mid-day
today through the weekend to address these concerns.

&&

.FIRE WEATHER...04/918 AM.

A dangerous fire weather scenario exists through Friday or
Saturday. The current heat wave is resulting in an unprecedented
stretch of extremely hot conditions with rapidly drying fuels.
Humidities over the interior areas will fall into the 5 to 10
percent range by Friday with poor overnight recoveries. Coastal
valley areas will also see humidities drop into the teens by
Friday. Meanwhile, northwest to northeast winds will gust to 20 to
40 mph tonight through Friday Night over southern Santa Barbara
County, many mountains, and the interior valleys like the Antelope
Valley. While classic Red Flag thresholds will likely not be met,
considering the extreme nature of this event and the holiday fire
ignition sources available, conditions are favorable for critical
fire weather activity and behavior. That is why Red Flag Warnings
and Fire Weather Watches have been issued.

There is a high risk for grass fires and plume dominated
wildfires. The public needs to be urged to refrain with anything
that can start a fire, especially in open spaces with dry fuels.
Fireworks, campfires, firearms, and dragging tow chains have all
started destructive wildfires in the past. Consider the risk for
firefighters and neighbors if a fire starts. Residents near large
open spaces and the wild land interface should have a plan on
what they will do if a wildfire breaks out. Visit
readyforwildfire.org and wildfirerisk.org for good resources.

&&

.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).
     Fire Weather Watch in effect from Friday morning through late
      Friday night for zones 342>345. (See LAXRFWLOX).
     Red Flag Warning in effect from 6 PM this evening to 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 2
      AM PDT Friday for zone 650. (See LAXMWWLOX).
     Small Craft Advisory in effect from 3 PM Friday to 3 AM PDT
      Saturday for zone 670. (See LAXMWWLOX).
     Small Craft Advisory in effect from 3 PM this afternoon to 9
      AM PDT Saturday for zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Lund/DB
AVIATION...Sirard
MARINE...DB/Sirard
BEACHES...Cohen
FIRE...Kittell
SYNOPSIS...MW/KL

weather.gov/losangeles

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