-- Discussion containing changed information from previous version are highlighted. --
053
FXUS66 KLOX 150616
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1116 PM PDT Fri Jun 14 2024

.SYNOPSIS...14/843 PM.

Strong to locally damaging north to northwest winds will affect
the interior mountains in northwest Los Angeles, northern and
central Ventura County, and southern and eastern Santa Barbara
Counties, as well as the Santa Barbara County South Coast and
Santa Ynez Range. The timing of these winds will be this evening
through the weekend. Warm to hot conditions will affect the region
with sunny skies on Saturday, and a slight cooling trend is
expected for Sunday. Dry conditions are expected through the
weekend. Low clouds will return to the coasts and coastal valleys
next week.

&&

.SHORT TERM (FRI-MON)...14/842 PM.

The upper level pattern tonight through Monday will feature a
broad upper level trough, that will sag over the region with
generally zonal flow aloft. In the low levels, the pattern becomes
much more significant. Strong north to northwest flow will begin
to strengthen tonight, with the latest NAM model showing 40-50 kts
at 950 MB over the coastal waters at times into Monday morning.
As winds will turn counterclockwise with height, related weak cold
advection will allow for general subsidence causing the gust
potential to increase at the surface.

The strong low-level winds are driven by impressive northerly
pressure gradients near the surface. As of 7 pm, we are seeing
the Santa Barbara-Santa Maria pressure gradient at -4 mb and is
expected to peak at around -4.5 mb tonight, then -5.5 mb by late
Saturday afternoon/evening. In addition, the Santa Barbara-
Bakersfield gradient is currently around 0 mb, and is expected to
trend sharply offshore tonight to around -4 mb by early Saturday
morning.

As of 8 pm, already seeing northwest winds increasing across the
favored areas with gusts between 30 and 50 mph common. For
tonight, the increased upper level wind support, cold air
advection, and tightening northerly pressure gradients will likely
bring warning level wind gusts of 50 to 65 mph for the western
Santa Barbara County South Coast (especially near Point
Conception) and adjacent mountains, the Ventura County mountains,
the I-5 Corridor, and the Antelope Valley western foothills.
Highways 101 and 154 (especially near Gaviota and San Marcos
Passes) will be particularly susceptible to strong cross winds
especially for locations below north-to-south oriented canyons.
The most western portions of the Antelope Valley may reach
advisory level winds this weekend, but such impacts are expected
to be highly localized. Due to channeling of wind down the I-5
corridor, winds are expected to build to advisory level at times
through Sunday morning for the Santa Clarita Valley. There is a
slight chance of local gusts up to 35 to 40 mph reaching the
northwestern San Fernando Valley, including areas like Porter
Ranch and the I-5 and 210 intersection.

For the eastern portions of Santa Barbara County, including the
eastern Santa Ynez Mountains, interior Mountain Ranges, and the
eastern Santa Barbara South Coast, winds are expected to build to
advisory level tonight. Warning level winds will then likely
extend to the eastern portion Saturday afternoon and night, in
part due to an increases in the northerly pressure gradients
and more favorable upper level wind support. The upcoming
sundowner wind event is expected to be widespread across southern
Santa Barbara county through Sunday night. In addition, the
sundowner winds will likely persist for longer duration than
normal across the western portions. And also of note, the
sundowner winds will likely impact the more populated areas
near Santa Barbara/Montecito and the adjacent foothills Saturday
afternoon into Saturday night. The combination of gusty winds,
very warm temperatures, and lowering humidities will bring
elevated fire weather conditions to southern Santa Barbara county
and much of the interior valleys, mountains, and Antelope Valley
through this weekend (See Fire Weather Planning Forecast for more
details on fire weather concerns).

*** From previous discussion ***

With the northerly offshore wind, temperatures in most areas will
be much warmer than normal. Of particular note, the HeatRisk
indicates a localized hot-spot for heat-related impacts over the
Santa Barbara County South Coast, where the potential will exist
for temperatures to locally reach up to 100 degrees even near the
coast. However, there is a moderate amount uncertainty with this
pattern. Local TempStudy data indicates a wide range of daytime
highs with similar atmospheric conditions. The uncertainty is a
result of competing factors, mainly compressional heating from
downsloping wind interacting with a cooling marine influence. Even
with uncertainty in daytime highs, with elevated minimum
temperatures and a dramatic swing from conditions earlier this
month, heat will feel significant, and precautions are advised for
this weekend. A Heat Advisory is in effect.

The only areas expected to see marine stratus will be the LA
County coast, and possibly the Ventura County coast by morning.
Then  rapid clearing should occur by late morning. High
temperatures in the coasts and coastal valleys on LA and and
Ventura Counties are expected to reach the 80s and perhaps around
90 away from the beaches.

The strong winds will likely dimish below warning levels by mid
to late morning Sun, but with north to south gradients remaining
steep, advisory level winds are possible for many areas through Monday
morning.

A modest cooling trend is expected for Sunday into Monday, as
midlevel heights continue falling over the western states by a
reinforced upper trough.

.LONG TERM (TUE-FRI)...14/301 PM.

For middle to latter parts of next week, broad and high-
amplitude upper troughing will persist across the western CONUS,
as a series of cyclonic perturbations advance through the flow
across the northwest states and adjacent Canada. Subsidence
upstream of the trough will favor continued surface ridging over
the east Pacific waters. This will maintain gusty northwest to
north winds in terrain-favored areas such as the I-5 corridor and
nearby VTA County Mountains and western Antelope Valley Foothills.
Present indications are that gusts should remain below Wind
Advisory thresholds starting Tuesday. However, there will be some
possibility for occasional advisory-level gusts (20% chance) if
smaller-scale enhancements to the east Pacific surface ridging
were to materialize.

The overall coast-parallel orientation of the low-level flow
across the coastal waters -- potentially favoring mesoscale eddy
development around the southern Channel Islands -- along with an
increasingly onshore surface pressure gradient across the larger-
scales, suggest that marine stratus will likely be supported
throughout middle and latter parts of next week. This would
especially be the case over a broader area of the coasts and
coastal valleys south of Point Conception. This could be
accompanied by night and morning fog and/or drizzle. Scattering
out and/or clearing of marine stratus should be less and less
from day to day as the marine layer deepens.

Meanwhile, compressional heating from downslope flow over
interior areas, beneath gradually building midlevel heights, will
support a warming trend farther inland through late week. This
will strengthen the temperature gradient across the forecast area
from day to day, with high temperatures by late next week
reaching the middle and upper 90s to around 100 degrees across the
interior valleys. High temperatures closer to the coast may not
rise above the upper 60s or lower 70s.

Otherwise, lacking midlevel moisture will prevent precipitation
development through the end of next week.

&&

.AVIATION...
-- Changed Discussion --
15/0615Z.

At 06Z at KLAX, the marine layer was 400 ft deep. The top of the
inversion was at 3300 ft with a temperature of 29 C.

Expect clear skies and VFR conds thru the period. The possible
exception is for some local MVFR an vsbys through the early
morning hours, and some possible LIFR to VLIFR cigs in coastal
sections of L.A. County from 11Z-16Z

KLAX...Moderate to high confidence in TAF. For tonight, there is
a 20-25% chance of IFR cigs 11Z-16Z. No significant easterly wind
component is expected.

KBUR...High confidence in TAF with VFR conds thru the pd.
-- End Changed Discussion --

&&

.MARINE...14/941 PM.

For the Outer Waters, moderate to high confidence in current
forecast. Gale Force winds have started through most of the outer
waters, and are expected to continue into Monday. Seas will peak
in the 12 to 15 foot range this weekend. GALE WARNINGS are in
effect through Monday. High- end Gale Force Winds are expected
especially over PZZ670 and PZZ673, where there is also a 20-30%
percent chance of Storm Force gusts (48 knots or greater) Saturday
through Sunday. On Tuesday, winds are expected to subside to SCA
levels.

For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. Strong SCA level winds have
developed, and winds are expected to increase to Gale Force Winds
Saturday through Sunday when a GALE WARNING is in effect.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. For the western Santa Barbara
Channel, high confidence in SCA level winds increasing to Gale
Force Winds Saturday through Sunday when a GALE WARNING is in
effect. For the rest of the southern Inner Waters, winds are not
expected to be as strong, though there is a 20-30% chance of SCA
level winds Saturday through Sunday.

Across all of the coastal waters, steep and dangerous seas can be
expected this weekend into at least early next week.

&&

.BEACHES...14/943 PM.

Hazardous beach conditions are expected to develop this evening
into tonight, and then continue through this weekend and early
next week. Significant wind-wave energy from relatively short-
period swell -- around 10-second wave periods generated by Gale
Force Winds winds over the nearby coastal waters -- will impact
all of the beaches starting later today. This will bring elevated
surf conditions and dangerous rip currents through early next
week. The latest data suggests that surf of 4-8 feet will likely
affect the Ventura County beaches, where a High Surf Advisory is
in effect. Elevated surf, with a 30-50% chance for High Surf
conditions, is expected for west-facing beaches along the Central
Coast and Los Angeles County. Locally elevated surf is expected
for the Santa Barbara County South Coast beaches, as well.

&&

.FIRE WEATHER...14/941 PM.

Rapidly increasing northwest to north winds are expected
tonight, especially across southern Santa Barbara County, the
Ventura county mountains, and I5 corridor where gusts of 35 to 50
mph are likely with isolated gusts to 65 mph possible. Meanwhile,
the air mass will warm and dry, with widespread 8 to 15 percent
humidities in the mountains and deserts. High temperatures between
90 and 100 will be common inland of the beaches. Poor overnight
recoveries in the foothills are also expected. This warm and dry
air will descend into some coastal foothills, including southern
Santa Barbara County. As a result, there is an elevated 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. The gusty wind pattern is expected to continue into early
next week.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect through Monday evening for
      zones 87-340-346-362-366. (See LAXCFWLOX).
     Wind Advisory now in effect until 11 AM PDT Sunday for zone
      88. (See LAXNPWLOX).
     High Wind Warning remains in effect until 11 AM PDT Sunday
      for zones 349-351. (See LAXNPWLOX).
     Heat Advisory remains in effect from 9 AM Saturday to 8 PM
      PDT Sunday for zones 349>352. (See LAXNPWLOX).
     Wind Advisory remains in effect until 6 PM PDT Saturday for
      zones 350-352-353. (See LAXNPWLOX).
     High Wind Warning remains in effect from 6 PM Saturday to 11
      AM PDT Sunday for zones 350-352-353. (See LAXNPWLOX).
     High Surf Advisory in effect until 7 PM PDT Monday for zone
      354. (See LAXCFWLOX).
     High Wind Warning now in effect until 11 AM PDT Sunday for
      zones 376>378-381. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 11 AM PDT Saturday for
      zones 645-650. (See LAXMWWLOX).
     Gale Warning in effect from 11 AM Saturday to 2 AM PDT Monday
      for zones 645-650. (See LAXMWWLOX).
     Gale Warning in effect until 2 PM PDT Monday for zones
      670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Gomberg/Schoenfeld/Cohen
AVIATION...DB
MARINE...Phillips/Cohen
BEACHES...Cohen
FIRE...Gomberg
SYNOPSIS...Cohen/Schoenfeld

weather.gov/losangeles

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