Area Forecast Discussion
Issued by NWS Los Angeles, CA

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032
FXUS66 KLOX 291753
AFDLOX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1053 AM PDT FRI JUL 29 2016

...Updated aviation discussion...

.SYNOPSIS...
The high will linger into the weekend for inland temperatures to
be above normal, with the beaches at normal in the marine layer.
Then next week the high will weaken and the onshore flow will
increase for more clouds and a cooling trend with temperatures
around normal.

&&

.SHORT TERM...(TDY-SUN)

Low clouds and fog with some patchy dense fog continued to affect
the Central Coast this morning, and patchy low clouds were noted
along the immediate coast s of Point Conception. The low clouds
along the Central Coast will clear away from the area by late this
morning, with mostly sunny skies expected across the forecast area
thru the afternoon except for some afternoon cu buildups in the mtns.
Good onshore gradients this afternoon (NAM fcst +8.0 mb LAX-DAG and
+6.4 mb SMX-BFL at 00Z) will result in gusty s to w afternoon winds
mainly for the foothills, mtns and deserts. Temps will again be
significantly warmer than normal this afternoon, with highs running
5 to 15 deg above average for this time of year. Highs in the
warmest vlys and foothills will reach the upper 90s to 106, except
107 to 110 in the Antelope Vly.

Fairly strong upper level ridging will persist over srn CA thru Sun.
500 mb heights will be about 594 dm today, then weaken slightly to
591 to 592 dm by Sun. 1000-500 mb thicknesses will range from 584 to
588 dm today, lowering slightly to 580 to 585 dm by Sunday. The
marine inversion which is below 1000 ft today should gradually
increase to near 1500 ft over the weekend, with very good onshore
gradients up to +9.0 mb LAX-DAG each afternoon.

Marine layer clouds and fog should expand along the coastal plain
and extend into some of the adjacent vlys night and morning hours
thru Sun. Afternoon clouds should also develop over the mtns and
deserts each day with marginal amounts of monsoonal moisture
filtering into the area from the e at mid levels. A 10 percent or less
chance of a thunderstorm cannot be ruled out as well in the mtns and
deserts, which is too small a chance to mention in the zones.
Otherwise, mostly clear skies will prevail thru the weekend across
the forecast area. Gusty afternoon and evening s to w winds will
persist across the foothills, mtns and deserts thru the weekend as
well. The onshore flow and gradually deeper marine layer will help
to lower temps some for Sat and Sun. Even so, highs will remain
several degrees above normal away from the coast. Highs by Sun in
the warmest vlys and foothills will be in the upper 80s and 90s,
except upper 90s to 103 in the Antelope Vly.

***FROM PREVIOUS DISCUSSION***

.LONG TERM...(MON-THU)

The upper high will linger over Nevada into Tuesday, then it
will be forecast westward off the coast as a trough moves thru
the Pac Nw Tue through Wed. The upper flow and moisture profile
look to be favorable for a slight chance of showers/tstms in the
mtns and Antelope Valley Mon and possibly Tue, then less so
thereafter. Expect minor day to day fluctuations in the night
through morning low cloud patter, generally confined to the
coastal plain, with max temps generally near normal thru the pd.


&&

.AVIATION...29/1800Z.

At 1030z, the marine layer was around 750 feet deep at KLAX. The
top of the inversion was near 4000 feet with a temperature around
29 degrees celsius.

N of Point Conception...moderate confidence in coastal tafs, with
marine layer clouds moving in overnight, with lower confidence in
timing. Cigs expected to fall to LIFR but 30% chance of IFR conditions.

S of Point Conception...Low to moderate confidence in 18z tafs
for coastal sites...high confidence inland. There is a 30% chance
that low clouds will not affect the KLAX...KLGB or KOXR. A 40%
chance KSBA will remain vfr.

KLAX...Low to moderate in taf...due to uncertainty in timing and
height of marine layer cigs overnight. there is a 20% chance of
IFR cigs...and a 30% chance the site will remain clear.

KBUR...High confidence in VFR conditions through the period.

&&

.MARINE...29/900 AM.
Moderate to high confidence with the forecast through this
weekend. Not expecting SCA winds, except for the coastal areas
around Point Conception where local gusts to 25 kt will be
possible this afternoon and evening. There is a 40% chance that
gusts could become more widespread and the SCA might need to be
added late this afternoon. Otherwise no significant issues across
the coastal waters through this weekend.

A small but long period southerly swell will develop Saturday
night through Sunday. Not anticipating any issues.


&&

.FIRE WEATHER...

29/900 AM.

Hot and dry conditions continue are expected to continue today with
widespread temperatures in the 90s and 100s across the interior with
minimum relative humidities in the 10s to low 20s. Locally gusty
onshore winds will continue during the afternoon and evening hours
across portions of the Los Angeles Mountains into the Antelope
Valley through at least early next week. Gradually improving
relative humidities and cooler temperatures will help to reduce fire
weather concerns this weekend into early next week as high pressure
aloft weakens and shifts to the east.
&&

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

&&

$$

PUBLIC...Sirard
FIRE...Munroe
AVIATION...Smith
MARINE...Smith
SYNOPSIS...Seto

weather.gov/losangeles



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