896
FXUS66 KLOX 011116
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
416 AM PDT Tue Oct 1 2024

.SYNOPSIS...30/519 PM.

It will be warmer each day today through Wednesday. Dangerously
hot conditions are expected across many valley, mountain, and
inland areas on Tuesday and Wednesday. A slow cool down will start
Thursday and persist into the weekend. Max temperatures, however,
will remain above normal away from the coast. Skies will be clear
through the period except for patchy night through morning low
clouds and fog across the coasts.

&&

.SHORT TERM (TDY-THU)...01/259 AM.

590 dam hgts will move into the area today as an East Pac upper
high noses into the center of the state from the west. These
higher than normal hgts will persist into Wednesday before fall
to 588 dam Thursday as the upper high weakens. At the sfc there
will near neutral flow this morning and only weak onshore flow in
the afternoon. Wednesday there will be offshore flow from both the
north and east in the morning turning very weakly onshore in the
afternoon. Thursday will see neutral flow in the morning but the
onshore push to the east in the afternoon will increase to about 4
mb. Skies will be mostly clear save for some coastal low cloud
and dense fog this morning.

The high hgts, sunshine and lack of significant onshore flow will
all combine to bring three days of dangerously hot weather to the
area. 5 to 10 degrees of warming today will be followed by 2 to 4
degrees of warming for the vlys and interior and 4 to 8 degrees
(due to the offshore flow) of warming for the coastal sections on
Wednesday. Most areas will cool 4 to 8 degrees on Thursday as the
hgts fall and the onshore flow increases. Max temps today and
Wednesday will be 6 to 12 degrees above normal across the coasts
and 10 to 20 degrees over normal for the inland areas.

Today and Wednesday across the vlys and interior look for daytime
highs between 95-105 with local readings nearing 110. On Wednesday
there is a 20 percent chance that additional heat advisories will
be needed over additional coastal areas such as Downtown Los
Angeles. While there will be some cooling Thursday there will not
be enough to eliminate the need for heat advisories across most of
SLO and SBA counties. For all of the details about the warnings
and advisories for this heat event please the product LAXNPWLOX.

The heat and low humidities will bring fire weather danger to the
area as well - please see the detailed fire weather discussion
below for all the details.

The high hgts have smooshed the marine layer to under a 1000 ft
and likely under 800 ft. This shallow marine layer has produced
areas of dense fog and a dense fog advisory is in effect for the
coastal sections from Avila Beach to Long Beach.

.LONG TERM (FRI-MON)...01/313 AM.

A PAC NW trof will knock down the ridge some on Friday. This along
with some more onshore trends will bring 2 to 5 degrees of cooling
to almost all the area. This should eliminate the need for heat
products but the max temps will still be 5 to 10 degrees above
normal.

There is better consensus now with all deterministic and ensemble
mdls for the weekend forecast and it looks like the ridge will
push back into the area from the SE and hgts will again rise to
591-592 dam. It looks like there will be more offshore flow
through the period as well. Warming is forecast both days and
there is a about a 50 percent chc that another round of heat
products will be needed. The offshore flow should eliminate the
threat of low clouds and skies should be clear through entire
weekend.

Slight cooling is forecast for Monday as the ridge begins to break
down. Max temps, however, will remain 6 to 12 locally 15 degrees
above normal.

&&

.AVIATION...01/1114Z.

Due to a data outage, current data is not available for KLAX.

High confidence in KPRB, KBUR, KVNY, KPMD, and KWJF.

Low confidence in coastal sites. For KSBP, there is a 30% chance
of LIFR to VLIFR conds until 16Z, and for KSMX there is a 30%
chance of no cigs developing this morning. South of Point
Conception, flight cat changes may be off by +/- 90 minutes, and
LIFR to VLIFR conditions will be possible at times through 16Z.

Low confidence for cigs/vsby this evening for all coastal sites.

KLAX...Low confidence in TAF. Flight cat changes may be off by
+/- 90 minutes this morning and low confidence in cigs/vsby this
evening. No significant east wind component expected.

KBUR...High confidence in TAF.

&&

.MARINE...01/308 AM.

In the Outer Waters (Central Coast to San Nicolas Island),
there is a 60-70% chance of SCA level winds from Point Conception
south to San Nicolas Island this evening through late tonight.
Then, moderate confidence in more widespread SCA winds level winds
Wed afternoon and night. There is a 20-40% chance for SCA level
winds in the afternoon thru evening hours Thurs thru Sat, with
best chances Friday and Saturday. Seas will decrease through today
before building again Wed through Fri.

For the inner waters along the Central Coast, there is a 20-40%
chance of SCA level winds Wed, Thur, and Sat afternoon and
evening.

For the Santa Barbara Channel and inner waters off the LA and OC
coasts, there is a 60-70% chance of brief SCA level winds across
the Santa Barbara Channel and from Pt Mugu through the San Pedro
Channel this afternoon and evening. Wednesday may also be windy
for the western portion of the SBA Channel and waters south of
Point Mugu, but more than likely will remain below SCA levels.
Otherwise, SCA conditions are not expected thru Sat.

Dense fog will impact portions of the coastal waters through at
least this morning. Mariners should be prepared for abrupt
visibility changes down to one nautical mile or less.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory remains in effect from 11 AM this morning to 8
      PM PDT Thursday for zones 38-341>345-347>349-351. (See LAXNPWLOX).
     Excessive Heat Warning remains in effect from 11 AM this
      morning to 8 PM PDT Wednesday for zones 88-372-373-378-379. (See LAXNPWLOX).
     Dense Fog Advisory in effect until 9 AM PDT Thursday for
      zones 346-349-350-354-355-362-366. (See LAXNPWLOX).
     Excessive Heat Warning remains in effect from 11 AM this
      morning to 8 PM PDT Thursday for zones 352-353. (See LAXNPWLOX).
     Heat Advisory remains in effect from 11 AM this morning to 8
      PM PDT Wednesday for zones 356>358-369>371-374>377-380-548. (See LAXNPWLOX).
     Fire Weather Watch in effect from Wednesday morning through
      Thursday evening for zones 342-345-353. (See LAXRFWLOX).
     Red Flag Warning in effect from 9 AM this morning to 8 PM PDT
      Thursday for zone 379. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 9
      PM PDT this evening for zones 650-655. (See LAXMWWLOX).
     Small Craft Advisory in effect from 3 PM this afternoon to 3
      AM PDT Wednesday for zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Rorke
AVIATION...Schoenfeld/Black
MARINE...Schoenfeld/Black
SYNOPSIS...30

weather.gov/losangeles

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