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856
FXUS66 KLOX 211024
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
324 AM PDT Fri Jun 21 2024

.SYNOPSIS...
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21/222 AM.

Above normal temperatures are expected today into early next
week, particularly for areas away from the coasts. Dangerously
hot conditions are possible this weekend, especially for the
mountains and Antelope Valley. There is a slight change of rain
showers or thunderstorms Saturday through Tuesday.
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&&

.SHORT TERM (TDY-SUN)...
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21/323 AM.

Today the trough overhead will weaken, giving way to high pressure
creeping in from the east. This area of high pressure will
overspread much of the southern United States on Saturday, with
SoCal under the westernmost portion. Heights will rise rapidly
today and Saturday, and then will stagnate for Sunday, when the
center of the high pressure starts to settle over Arizona and New
Mexico. With rising heights compressing the marine layer and
decreasing onshore pressure gradients, cloud cover will be minimal
today. Additionally, temperatures will increase by 4 to 10
degrees across the region compared to the previous day.

For most areas, daytime highs will peak over the weekend. Expect
temperatures ranging from 102 to 108 degrees across the Antelope
Valley, from 90 to 100 for the interior valleys, and in the mid
80s to mid 90s for inland coastal plains. Only the beaches will
see temperatures in the 70s, with upper 60s possible along the
Central Coast. Minimum temperatures will be warm Saturday and
Sunday night, offering little relief from the heat, especially for
inland locations. Overnight lows will be as warm as 80 degrees
for portions of the Antelope Valley and some mountain areas.
Excessive Heat Watches have been issued for this weekend, that
include the Antelope Valley and foothills, the San Gabriel
Mountains, Ventura Mountains, Interior Santa Barbara Mountains,
and the I-5 Cooridor. Heat Advisories have also been issued for
the weekend, to include interior San Luis Obispo County, the Santa
Clarita Valley, the San Fernando Valley, and the San Gabriel
Valleys. Please see the product LAXNPWLOX for all of the details.
With little change to the pattern going forward, theses heat
products may be extended into mid next week.

There is a chance of showers or thunderstorms across Los Angeles
County and the southern coastal waters on Sunday. A stream of
moisture from the remnants of Tropical Storm Alberto will be
funneled into the region within the anticyclonic flow around the
high pressure. Even if no showers develop, the additional mositure
will increase humidities and slightly moderate temperatures,
dampening daytime highs and raising overnight lows. This will
further intensify the impacts of the high temperatures both
during the day and overnight. Heat related preparations and
precautions are advised for this weekend.

.LONG TERM (MON-THU)...21/308 AM.

Both the GFS and the EC as well as their respective ensembles
agree that the large and warm upper high will remain over the
AZ/NM region through Wednesday and then push off to the east on
Thursday. Hgts will remain near 594 dam though Wed and fall a few
dam on Thu.

There is good agreement that the predominate flow pattern will be
from the SW on Mon and Tue. This will keep any monsoon moisture
well to the east of the area. On Wednesday some ensemble members
begin to hint at a more southerly or even southeasterly flow
pattern with some chance of a monsoon moisture push. There is
still not enough agreement to put convection into the fcst but
this day will need watching. The eastward progression of the upper
high Thursday will bring dry SW flow to Srn CA and eliminate any
convective threat.

The combination of a strong East Pac high and strong thermal low
over the CA/AZ border will produce a strong (~9mb) W to E onshore
push each afternoon. This will bring near advisory level winds to
the western Antelope Valley and foothills each afternoon.

The very strong marine inversion will continue through the period.
Night through morning low clouds and fog (likely dense at times)
will continue across the near shore areas through the period.
Despite the strong onshore push the low clouds will not extend
too far inland since the marine will will be squashed down to ~500
ft. The combination of a very strong capping inversion and strong
afternoon onshore flow will likely keep many west facing beaches
cloudy all day.

Hgts fall just enough Monday to bring 2 to 4 degrees of cooling to
the area. This should be enough to bring temps just below advisory
criteria. After that, with hgts and gradients fairly similar
through Thursday there will not be much day to day change in
temperatures. Max temps will remain 8 to 10 degrees above normal
across the mtns and far interior, 4 to 6 degrees above normal for
the vlys and a few degrees either side of normal for the near
shore areas.
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&&

.AVIATION...21/0649Z.

At 0515Z at KLAX, the marine layer was 1100 feet deep. The top of
the inversion was at 2300 ft with a temperature of 21 deg C.

Very good confidence in TAFs for KSBA, KOXR, KCMA, KBUR, KVNY,
KPMD and KWJF.

Moderate confidence in TAFs for KPRB, KSBP and KSMX where flight
cat changes could be off by +/- 90 minutes and cigs hgts off by
300 ft.

Low confidence in TAFs for KSMO (40 percent chc of MVFR cigs
12Z-17Z) and KLAX and KLGB (40 percent chc of no cigs).

KLAX...Low confidence in TAF. There is a 40 chance of no cig/vsby
restrictions tonight. No significant east wind component is
expected.

KBUR...High confidence in TAF.

&&

.MARINE...
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21/233 AM.

For the Outer Waters, high confidence in current forecast. Small
Craft Advisory (SCA) winds will continue through this evening.
Thereafter, SCA conditions are not expected through at least early
next week.

For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. SCA winds are likely this
afternoon and evening after a brief lull this morning. Thereafter,
SCA conditions are not expected through at least early next week.

For the inner waters south of Point Conception, moderate to high
confidence in current forecast. SCA winds are not expected over
most of the area, but the western third of the Santa Barbara
Channel will have local gusts to 25 kts this afternoon and
evening. Otherwise, SCA conditions are not expected through at
least early next week.

There is a slight chc for a few thunderstorms across the southern
portion of the local waters this weekend, as remnant upper-level
moisture from Tropical Cyclone Alberto advances into the region.
Please see the Marine Weather Statement (LAXMWSLOX) for
additional information.
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&&

.LOX WATCHES/WARNINGS/ADVISORIES...
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CA...Heat Advisory remains in effect from 10 AM Saturday to 8 PM
      PDT Sunday for zones 38-88-343>345-372-373-548. (See LAXNPWLOX).
     Excessive Heat Watch remains in effect from Saturday morning
      through Sunday evening for zones 353-376>383. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Saturday for
      zones 645-670-673-676. (See LAXMWWLOX).
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&&

$$

PUBLIC...Schoenfeld/Rorke
AVIATION...Rorke
MARINE...Rorke
SYNOPSIS...jld/RS

weather.gov/losangeles

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