Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 260614
AFDLOX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1114 PM PDT THU AUG 25 2016

Updated Aviation Section

.SYNOPSIS...

Marine layer clouds will persist along the coast and some valleys
night and morning hours through late next week, otherwise mostly
clear skies will prevail. Cooler temperatures can be expected into
the weekend as a weak upper level trough of low pressure moves in.
High pressure will build into the area Sunday and into early next
week for above normal temperatures in many areas, followed by a
cooling trend thru mid week as low pressure moves back in.
&&

.SHORT TERM...(THU-SUN)

Upper level trough will continue to deepen across California
during next 24 hours. Already saw a cooling trend with stronger
onshore flow today. Heights/thicknesses will continue to fall on
Friday,leading to additional continue for many areas on Friday.
Most inland areas will only be in the 80s on Friday, with the
exception of the Antelope Valley climbing into the lower 90s. 00z
Vandenberg sounding showing marine layer depth around 1700 feet.
ACARS sounding showing marine layer depth around 1600 feet across
the LA basin, but should deepen to around 2000 feet by Friday
morning.

Satellite imagery already showing low clouds developing across
the LA coast and Central Coast this evening. With the deepening
marine layer and stronger onshore flow, expecting low clouds
to fill into many valley locations overnight into Friday morning.
Also expecting some low clouds to linger across some immediate
coastal areas on Friday afternoon. The increased marine layer
influence on Friday is expected to better humidity recoveries and
cooler temperatures to both the Chimney and Rey wildfires tonight
into Friday, however there will be the potential for gusty onshore
winds at both fire locations during the afternoon hours.

***From previous discussion***

We`ll turn the corner over the weekend as the trough exits to the
east and is replaced by an even stronger high pressure ridge than
we had a couple days ago. Temps will nudge upward Saturday but
bigger jumps Sunday as the ridge builds.

.LONG TERM...(MON-THU)

The ridge will strengthen further Monday and peak early Tuesday.
Warmer valley highs expected to climb into the lower triple digits
(100-103). For coastal areas gradients do trend offshore but not
really enough to offset the marine lyr impacts. Still, inland
coastal areas should reach the mid to high 80s early next week.

The ridge starts weakening Tuesday, though initial cooling should
be confined to northern areas. For southern areas high Tuesday
shouldn`t be much different than Monday and possibly even a degree
or two warmer across the interior. Beyond Tuesday models differ
with respect to the pattern, with the GFS showing just a slight
cool down mid to late week then turning warmer again by next
weekend. The ECMWF shows a continued cooling trend through the
period. Have trended towards the warmer GFS solution as that seems
to have been the better performer lately.

&&

.AVIATION...26/0600Z.

At 06Z, the marine layer depth was around 1800 feet deep at KLAX.
The top of the inversion was near 4300 feet with a temperature
around 22 degrees Celsius.

North of Point Conception...Predominantly IFR conditions will
spread into coastal and valley terminals through 13Z. There is a
chance of LIFR conditions between 08Z and 16Z. VFR conditions
should develop between 16Z and 18Z. There is a slight chance of
MVFR conditions lingering at coastal terminals through the
afternoon.

South of Point Conception...Predominantly MVFR conditions will
spread into coastal and valley terminals through 13Z. MVFR
conditions should linger through at least 16Z with coastal
terminals likely struggling to clear on Friday. There is a slight
chance of MVFR conditions lingering through the afternoon.

KLAX...High confidence in the current forecast. MVFR conditions
should linger through at least 18Z...or as late as 21Z. There is a
20 percent chance of mvfr cigs lingering through the afternoon
hours on Friday.

KBUR...High confidence in the current forecast. MVFR conditions
should linger through at least 16Z...or as late as 18Z. There is a
20 percent chance of mvfr cigs lingering through the afternoon
hours on Friday.

&&

.MARINE...25/800 PM.

Conditions will remain below advisory levels through Saturday.
Winds across the outer waters will strengthen late Saturday and
Small Craft Advisories may be needed for some areas by Sunday.

Patchy fog will be widespread across the coastal waters through
Saturday...mainly during the overnight through morning hours.

&&

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

&&

$$

PUBLIC...Gomberg/MW
AVIATION...Hall
MARINE...Smith
SYNOPSIS...Sirard

weather.gov/losangeles


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