Gale Watch 34, NWS Los Angeles, CA

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1142 PM PDT Fri Aug 13 2021

.SYNOPSIS...13/745 PM.

High pressure will build over the region through this weekend
with an associated warming trend. Excessive heat is expected to
begin Saturday in the far interior areas, and across the mountains
and some of the valleys Sunday. Hot conditions will persist
through Monday afternoon, along with locally gusty onshore winds.
Cooler conditions are expected by midweek.

&&

.SHORT TERM (FRI-MON)...13/808 PM.

***UPDATE***

A strong upper high centered over the Western States will
gradually spread westward and strengthen through Sunday, before
weakening some on Monday. Southeast flow around the high will
begin to draw mid-level monsoonal moisture over the region
starting early Saturday. The moisture, along with instability
caused by the significant daytime heating, will likely cause some
cumulus buildups over the mountains and Antelope Valley Saturday
and Sunday afternoons. However, the chance of rain is very low as
the lower levels remain very dry, and the chance of thunderstorms
is ten percent or less.

Heat Warnings are in effect for the interior deserts Saturday
through Monday, with heat advisories for the mountains, the Santa
Clarita Valley, and the western San Fernando Valley. Sunday looks
to be the peak heating of the event, with highs ranging from 102
to 108 over the areas under excessive heat products. Warm nights
are expected as well during this time, with overnight lows in the
70s to near 80, adding to the heat stress.

Gusty onshore winds will weaken some during this time as onshore
gradients diminish, but the locally gusty winds combined with high
temperatures and low humidities will create elevated fire
conditions over interior areas.

Meanwhile, a shallow marine layer will linger near the coast.
While the Central Coast is likely to keep seeing low clouds and
fog during the overnight periods, the areas further south may
continue seeing more limited coverage. For tonight, portions of
the LA Basin should see low clouds for at least a few hours, with
a chance of low clouds and fog along the western edge of the
Oxnard Plain.

.LONG TERM (TUE-FRI)...13/223 PM.

Better cooling is on tap for Tuesday as an upper level trof moves
out of the Pacific NW and down through northern California.
Heights should fall to about 589 dam. There will also be a little
stronger onshore flow. Look for 4 to 8 degrees of cooling across
the interior and 1 to 3 degrees of cooling for the coasts and
valleys.

Broad troffing will be over the state on Wednesday as the
positively tilted upper-level low moves into Idaho, but locally
the heights may pop back up to 592 dam and bring back a bit of
inland warming. Low clouds and fog are expected over the near
shore areas during the night through morning hours and couple more
degrees of coastal cooling in the afternoon may occur. Wednesday
will also see a possible return of some afternoon cumulus in the
eastern San Gabriel mountains.

A broad area of 588 to 590 dam heights looks to settle over the
area on Thursday and Friday with another 2 to 3 degrees of
warming possible.

&&

.AVIATION...14/0642Z.

At 0505Z at KLAX, the marine layer was 700 feet deep. The top of
the inversion was around 1700 feet with a temperature of 26 C.

High confidence in desert and valley TAFs including KPRB.

Moderate confidence in coastal TAFs north of Point Conception.
Timing of cig arrival may be off by +/- 2 hours. There is a 30
percent chc of VLIFR conds at KSBP 12Z-15Z and a 30 percent chc
of no VLIFR conds at KSMX.

Low confidence in coastal TAFs south of PT Conception. There is a
40 percent chc of no clouds at any site. Timing of cig arrival
could be off by +/- 2 hours. Better confidence in VFR transition.

KLAX...Low confidence in TAF. There is a 40 percent chc that low
clouds will arrive and then dissipate 2 to 3 hours later with only
a 50 percent chc of reforming around 13Z. If low clouds do arrive
the VFR transition may occur as late as 17Z. Good confidence that
any east wind component will be 3 kt or less.

KBUR...High confidence in TAF.

&&

.MARINE...13/814 PM.

High confidence that winds and seas will remain below Small Craft
Advisory (SCA) level through Saturday morning. There is a 40%
chance of widespread SCA level NW winds from the Central Coast to
San Nicolas Island on Saturday afternoon and evening. Higher
confidence in SCA conditions on Sunday afternoon lasting through
at least Monday. There is a 40-50% chance for Gale force winds
Sunday evening through Monday night for the outer waters north of
Point Conception.

South to southeast swells 3 to 4 feet with 14-15 second periods
are expected through early next week from Hurricane Linda.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning in effect from 10 AM Saturday to 8 PM
      PDT Monday for zones 37-38-51-59. (See LAXNPWLOX).
     Heat Advisory in effect from 10 AM Sunday to 8 PM PDT Monday
      for zones 52>54-88-547. (See LAXNPWLOX).
PZ...NONE.

&&

.HAZARD POTENTIAL OUTLOOK (MON-FRI).

Hot conditions in the San Luis Obispo interior and Antelope Valley
will peak on Sunday and continue into Monday. The Los Angeles
County mountains and Santa Clarita will likely also be quite hot
on Sunday.

&&

PUBLIC...Smith/Rorke/jld
AVIATION...Rorke
MARINE...Stewart
SYNOPSIS...Smith

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