878
FXUS66 KLOX 270436
AFDLOX
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
936 PM PDT Fri Jul 26 2024
.SYNOPSIS...26/132 PM.
Cooler temperatures are expected this weekend as high pressure
aloft weakens. High temperatures will drop to 4 to 8 degrees
below normal across the region with an increase in morning low
clouds and fog for coasts and some valleys. Locally gusty
winds are expected during the afternoon and evening for the Santa
Barbara southwestern coast and the Antelope Valley. Starting
Monday, temperatures will gradually trend warmer each day.
&&
.SHORT TERM (FRI-MON)...26/712 PM.
***UPDATE***
Fairly quiet weather day today. Onshore trends and lower hgts
brought 3 to 6 degrees of cooling to the entire area. Despite the
cooling, most max temps remained 2 to 4 degrees above normal today
with the only exception being the Central Coast where max temps
ended up 2 to 4 degrees blo normal. Some CU did develop over the
mtns but there little in the way instability and none of the
clouds showed any vertical development.
The more difficult forecast is the marine layer stratus pattern.
Low clouds are hugging the beaches of the Central Coast but there
are just a few patches of low clouds milling about south of Pt
Conception. Super low confidence in exact timing of the arrival of
the low clouds, but quite good confidence that by dawn most of the
coasts and portions of the lower vlys will be covered with
stratus.
The cooling forecast for tomorrow remains on track. Look for still
lower hgts and even stronger onshore flow to combine to bring 4 to
8 degrees of cooling to most areas.
Forecast is in good shape and no updates are planned.
***From Previous Discussion***
A relatively quiet and much cooler period of weather is expected
across the southland through the weekend. Highs actually expected
to be BELOW normal for the first time in several weeks, by as much
as 10 degrees in some areas but on average 3-7 degrees cooler than
normal. This is all due to a low pressure system that will move
into northern California Saturday, followed by lingering
troughiness into Sunday. This will deepen the marine layer over
the weekend, possibly reaching the coastal valleys. Skies will
clear in the afternoon in most areas except some beaches may stay
cloudy well into the afternoon. Southwest flow aloft will keep the
area free of any convection, though a few cumulus clouds are
possible near the higher peaks in the afternoon.
High pressure will build up from the south starting Monday, which
will be the beginning of the next warming trend that will last
through next week.
.LONG TERM (TUE-FRI)...26/212 PM.
High pressure will continue to build up from the desert southwest
through California next week with the center of the high around
the 4 corners region. Ensembles show very strong consistency in
this feature so there is high confidence in the warming trend.
However, it will a slow climb and most areas won`t even be back to
normal high temperatures until at least Wednesday. After mid week
temperatures will continue to climb, rising 2-3 degrees each day
through next Saturday. Highs across the Antelope Valley will be
approaching 110 degrees as early as next Friday, while the warmer
coastal valleys will be approaching 105. The probabilities for
those sites to reach 110 by Saturday are about 30% and 10%
respectively.
With the high pressure system settling in near the 4 corners that
definitely raises the potential for monsoon moisture moving into
the area from the southeast. The deterministic 12z GFS actually
shows quite a favorable upper air pattern by next Fri with an
inverted trough across southern California and quite a bit of PVA
and instability. And to go along with that, ensembles are
indicating a rapid increase in PW`s late next week and next
weekend to over 1 inch across the area. Expect there will be at
least isolated thunderstorms across the eastern part of LA County
(mountains and Antelope Valley) during this period, possibly
expanding west into the Ventura mountains. And if that GFS upper
air solution comes to fruition that certainly increases the
chances for showers and storms closer to the coast as well.
&&
.AVIATION...26/2352Z.
At 2215Z at KLAX, the marine layer was 800 feet deep. The top of
the inversion was around 2400 ft with a temp of 28 C.
High confidence in valley/desert TAFs, but low to moderate
confidence in coastal TAFs. There is a 25 percent chc of no cigs
for coastal TAFs KSBA and south. If cigs do arrive timing could be
off by as much as 2 hours. VFR transition may occur 1 hour earlier
than fcst.
KLAX...Moderate confidence in TAF. There is a 25 percent chc of no
cigs. If cigs do form they could arrive as early as 06Z or as late
as 10Z. There is a 30 percent chc of VFR conds arriving at 17Z.
No significant easterly wind component is expected.
KBUR...High confidence in CAVU TAF.
&&
.MARINE...26/935 PM.
For the Outer Waters, moderate to high confidence in current
forecast. For PZZ673/676, high confidence in Small Craft Advisory
(SCA) level winds continuing through Sunday night. For Monday
through Wednesday, there is a 60-80% chance of the SCA level winds
continuing. For PZZ670, there is a 60-80% chance of SCA level
winds through Saturday night. For Sunday through Tuesday, there
is a 40% chance of SCA level winds...then a 60% chance of SCA
level winds on Wednesday.
For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. Today through Saturday, there is a
60-70% chance of SCA level winds in the afternoon and evening
hours. For Sunday through Wednesday, there is a 50-60% chance of
SCA level winds, mainly in the afternoon and evening hours.
For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. For the western half of the Santa
Barbara Channel, there is a 60-70% chance of SCA level winds
tonight and Saturday, mainly in the late afternoon and evening
hours. Otherwise for the southern Inner Waters, high confidence in
winds and seas remaining below SCA levels today through
Wednesday.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory remains in effect until 6 AM PDT Saturday for
zones 349-351. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from noon to 9 PM PDT Saturday
for zone 645. (See LAXMWWLOX).
Small Craft Advisory in effect until 3 AM PDT Saturday for
zone 650. (See LAXMWWLOX).
Small Craft Advisory in effect until 3 AM PDT Sunday for zone
670. (See LAXMWWLOX).
Small Craft Advisory in effect until 3 AM PDT Monday for
zones 673-676. (See LAXMWWLOX).
&&
$$
PUBLIC...MW/Rorke
AVIATION...Rorke
MARINE...RAT/Gomberg
SYNOPSIS...MW
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox
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