Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 292357 AAA
AFDLOX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
457 PM PDT Wed Mar 29 2017

...update for new aviation discussion...

.SYNOPSIS...
A trough of low pressure will bring cooler conditions for
Thursday and Friday with another round of gusty northerly winds. A
brief warmup is likely this weekend with ridge of high pressure
nosing into the region, before another trough brings cooler and
breezy conditions early next week.

&&

.SHORT TERM...(TDY-SAT)

A warm day across the area as high pressure combined with weak
offshore flow generated strong compressional heating. Although
below record levels, temps are still 10-20 degrees above normal.
Significant cooling, though still near to slightly normal,
expected Thu as a trough that is currently moving into northern CA
will shift the offshore flow to strongly onshore. So in addition
to the cooler temps we`ll see strong west to northwest winds
developing in the afternoon, especially along the Central Coast,
srn SB County, all the mountains, and the Antelope Valley. High
wind watches were posted earlier for all those areas except the
Central Coast, which certainly will need advisories for tomorrow
as will much of the remainder of the area by late afternoon or
evening.

This wind event is expected to be on par with the event we had
Monday night into early Tuesday. Strongest winds at that time were
in the I5 corridor where gusts in excess of 80 mph were observed
at Whitaker Peak just above Interstate 5. Will probably see
similar speeds Thu night. The advisory level winds will include
coastal LA County where more gusty north winds are expected
through and below the Hollywood Hills.

Winds will remain gusty through Friday though below advisory level
after Friday morning. With the cooler air arriving with the trough
expect another few degrees of cooling Friday.

Then we bounce back up Saturday as gradients shift to offshore
and the northeast (Santa Ana) winds kick in. Might be a low end
advisory level Santa Ana event Saturday, though fairly brief as
upper support and gradients weaken late Sat. Highs will jump a
good 5-10 degrees from Friday, pushing highs again well into the
80s for the valleys and near 80 for interior coastal zones.

.LONG TERM...(SUN-WED)

Another pretty warm day Sunday, though likely a few degrees cooler
especially for coastal areas as offshore flow weakens. Models
continue to bounce around a little bit with the Monday trough.
Though virtually all solutions now are dry, the big question
remains how far south the trough will dig and whether we`ll see
another burst of strong north winds late Monday into Tuesday.
Either way we should see another few degrees of cooling Monday,
then warming Tuesday/Wednesday as a ridge of high pressure
develops along the west coast and gradients turn weakly offshore.

&&

.AVIATION...29/2355Z

At 2255Z, the inversion at KLAX was 100 ft deep. The top of the
inversion was at 1200 ft with a temperature of 22 deg C.

Generally hi confidence in the 00Z TAFs. VFR conditions are expected
at all the airfields thru Thu, except there should be a period of
IFR/MVFR vsbys at KPMD and KWJF aft about 21Z Thu due to blowing
dust. There is, however, the slight chance (20 percent) of low
clouds with IFR cigs developing around KLAX and KLGB aft about 12Z
thru mid morning Thu. Gusty nw winds will affect KSBP and KSMX Thu
afternoon, with gusty w winds at KOXR, KCMA and KLAX, and gusty n
winds at KVNY. Very strong w winds can be expected at KPMD and KWJF
late Thu morning thru the afternoon, with gusts up to 50 KT
expected, contributing to the reduced vsbys in blowing dust.

KLAX...Generally hi confidence in the 00Z TAF. VFR conditions are
expected thru Thu evening. However, there is the slight chance (20
percent) of low clouds with IFR cigs developing aft about 12Z thru
mid morning Thu.

KBUR...Hi confidence in the 00Z TAF with VFR conditions expected
thru Thu afternoon.

&&

.MARINE...29/200 PM

Across the Outer Waters...A combination of winds and seas will
keep Small Craft Advisory conditions through at least Thursday
morning. Gale force winds are likely Thursday afternoon through
Friday.

Across the Inner Waters...Strong SCA winds will affect the
western portions of the inner waters on Thursday and Friday with a
40 percent chc of gale force winds.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Wind Watch in effect from Thursday evening through
      Friday morning for zone 46. (See LAXNPWLOX).
     High Wind Watch in effect from Thursday afternoon through
      Friday morning for zones 52>54. (See LAXNPWLOX).
     High Wind Watch in effect from Thursday afternoon through
      late Thursday night for zone 59. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 PM PDT Friday for zone
      645. (See LAXMWWLOX).
     Small Craft Advisory in effect until 1 PM PDT Thursday for
      zones 670-673-676. (See LAXMWWLOX).
     Gale Watch in effect from Thursday afternoon through Friday
      afternoon for zones 670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(SAT-WED)
Gusty northeast winds are possible Saturday across LA/Ventura
counties.

&&

$$

PUBLIC...MW
AVIATION...Sirard
MARINE...Sweet
SYNOPSIS...Munroe

weather.gov/losangeles



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