Area Forecast Discussion
Issued by NWS Los Angeles, CA

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557
FXUS66 KLOX 230710
AFDLOX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1210 AM PDT Wed Aug 23 2017

.SYNOPSIS...

A weak trough over the Coastal Waters will bring overnight low
clouds to the coast and valleys through Thursday morning. As the
low moves east of the area, overnight low clouds will retreat to
coastal areas. As high pressure builds over the area, a warming
trend is expected Friday through the middle of next week. Very
warm temperatures are likely, with the peak heating on Monday and
Tuesday.

&&

.UPDATE...

There are some low clouds across the Central Coast and between
Catalina Island and Orange County. Max temps today were about the
same at the coast...a couple of degrees up over the
mtns...Antelope Vly and the interior Vlys. The biggest jump in
temps was across the vlys where there was 4 to 8 degrees of
warming.

Biggest issue tonight is the return of the low clouds. Its likely
that by sunrise all of the coasts will be covered in clouds but
there is a fair chc that the San Fernando Vly will be clear
through the morning.

Current forecast is in good shape and no updates are planned.

&&

SHORT TERM...(WED-SAT)

Models also show moisture filling in below the inversion base
south of Pt Conception tonight as well so better coverage overall
is expected by Wednesday morning. Along with this there is a 1-2mb
onshore trend. So in addition to an increase in low clouds
tomorrow most coast/valleys should be a degree or two cooler as
well for highs.

After that we should begin a slow warming trend through the rest
of the work week. Gradients trends weakly offshore each day
leading to a weaker onshore flow.

LONG TERM...(SUN-WED)

Little change or slight warming Saturday, then more significant
warming as we get into Sunday, Monday, and especially Tuesday
where light offshore flow could finally bring some of that inland
heat to the coast. Warmer valley spots should see triple digits by
Sunday and likely 105 or higher by Tuesday. Inland coastal areas
like downtown LA probably won`t see 90 until Monday or Tuesday but
still above normal by Sunday. Temps expected to keep on climbing
through most of next week as well, possibly leading to some heat
advisories and/or excessive heat warnings by as early as Tuesday.
Models still so far not showing any monsoon moisture with this
heat wave so thunderstorms remain out of the forecast.

&&

.AVIATION...23/0709Z.

At 06Z, the marine layer depth was around 1300 feet deep at KLAX.
The top of the inversion was around 2150 feet with a temperature
of 23 degrees Celsius.

Moderate confidence in the current forecast. Predominantly IFR
conditions, except for MVFR for Los Angeles County Coastal
terminals will likely spread into coastal and valley terminals
through 13Z. There is a chance of LIFR conditions for terminals
north of Point Conception between 08Z and 16Z. VFR conditions
should redevelop between 16Z and 20Z.

KLAX...MVFR conditions will likely linger through 18Z, but there
is a chance of MVFR conditions lingering until 20Z.

KBUR...There is a 60 percent chance of IFR to MVFR conditions
betwee 13Z and 17Z. Otherwise, VFR conditions are expected
through the period.

&&

.MARINE...22/815 PM

Outer waters...good confidence in current forecast. Sub Small
Craft Advisory (SCA) conditions through Wednesday. SCA levels will
likely develop Thursday afternoon with building seas to around 7
ft into Saturday morning. There will be a small S swell mixed with
the W-NW swell at times.

Inner waters...good confidence in the current forecast. For the
waters north of Point Sal, winds and seas will remain below SCA
levels through Wednesday. On Thursday and Friday, SCA level winds
are likely each afternoon and evening with winds diminishing below
SCA levels on Saturday and Sunday. For the waters south of Point
Conception, winds and seas are expected to remain below SCA levels
through the weekend.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

.HAZARD POTENTIAL OUTLOOK...(SAT-WED)
A significant heatwave could develop this upcoming weekend and
continue into early next week.

&&

$$

PUBLIC...MW/Rorke
AVIATION...Hall
MARINE...Boldt/ASR
SYNOPSIS...Smith

weather.gov/losangeles



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