Area Forecast Discussion
Issued by NWS Los Angeles, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KLOX 241010
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
310 AM PDT Sat Jun 24 2017

.SYNOPSIS...
High pressure centered over Southern Arizona will continue to
bring very warm conditions to all areas except the coast through
early next week. Night through morning low clouds and fog will
continue into next week. High pressure aloft will weaken Tuesday
and a cooling trend should develop as onshore flow increases.

&&

.SHORT TERM...(TDY-MON)

The marine layer has shrunk a few hundred feet (its at 1400 feet
now)...there are weak offshore trends from the north and the
powerful ridge continues to sit directly atop the state with 594
hgts. All of this will add up to another very warm day with little
change from the very hot temps across the interior and the cool
temps across the coastal areas which are swaddled in cool marine
air. The vlys will see a bump up in temps of 2 to 4 degrees as the
marine layer retreats.

The offshore trends will allow for a little better clearing of the
marine layer this afternoon but more than a few west facing
beaches will likely remain cloudy.

A little instability and some mid level moisture is working its
way up from the north. This is creating some elevated convection.
There is a slight chc of some dry lighting this morning from this
system but the only chc or rain and thunder is over the southern
outer waters where the convection has been training for the past 7
hours. The mtns and esp the VTA mtns are rather unstable today and
there is even some decent CAPE to complement the instability but
there is still no low level moisture so still expecting a large
field of ACCAS but not much else. The chc of a mtn TSTM is not
zero but it is too low to mention in the forecast. Would not be
too surprised if there were a few reports of big raindrops.

Continued offshore trends tonight will result in a greatly reduced
marine layer. Quite confident that the vlys will be clear and that
most of the Central Coast and the LA coast will be cloudy but the
VTA county coast is the big question mark. Keeping it clear for
now but would not be surprised if the clouds sneak in late.

The ridge begins to break down on Sunday and this will result in
some cooling across the interior including the Antelope Vly which
will see its first slight relief in a week. But the offshore
trends and reduced marine layer will bring a warming trend to the
coasts and vlys.

The ridge continues to flatten out on Monday so the cooling trend
will continue across the interior and will spread to the coasts
and vlys which will have a similar marine layer and pressure
gradient pattern as Sunday but lower hgts overhead.

.LONG TERM...(TUE-FRI)

The EC blinked first and after 3 days of disagreement now
resembles the GFS through the xtnd period. An upper low rolls
through the Canadian Rockies and a long wave trof will slowly
develop and expand across the western CONUS. There will be
continued cooling Tue and Wed and then Thu and Fri will see little
change. The marine layer will grow Tue and Wed when it will cover
most of the coasts and vlys. The marine layer stratus pattern will
then also change little on Thu and Fri.

&&

.AVIATION...

24/0600Z

At 0546Z at KLAX, the marine layer depth was around 1100 feet.
The top of the inversion was around 4200 feet with a temperature
near 29 degrees Celsius.

Only moderate confidence in coastal TAFs as mid level clouds could
disrupt the low clouds leading to VFR conds. There is 40 percent
chc that low clouds will not reach KVNY and KBUR. There is a 30
percent chc that TAF sites with no afternoon clearing forecast
will clear by 22Z. Low confidence in low clouds redevelopment
after 00Z for all coastal TAFs.

KLAX...Moderate confidence in TAF. There is a 10 percent chc of
clearing by 14Z. There is a 30 percent chc that there will be
clearing by 22Z. Low confidence in TAF after 00Z with a 40 percent
chc of VFR conds. For west departures through 12Z there is a 20
percent chc of lightning 120 NM west of the terminal.

KBUR...Low confidence in TAF through 17Z. There is a 40 percent
chc of no low clouds tonight. Good confidence in TAF after 17Z.

&&

.MARINE...

24/300 AM.

Outer Waters...Winds will gradually increase through the weekend,
increasing above Small Craft Advisory levels this morning for the
two lower outer water zones from Point Sal to NW of San Nicolas
Island. By this afternoon, the outer northern waters will
increase to SCA level winds as well. Small Craft advisories for
the outer waters have been extended through at least late Sunday
night, and will likely need to be extended into early next week.

Inner Waters...N of Point Conception, SCA will be in effect this
afternoon through mid evening hours. This will be on the low end
of the scale. There will be a 50% chance that SCA will be needed
Sunday afternoon and evening, and a 70% chance for Monday
afternoon and evening.

S of Point Conception... A SCA has also been issued valid for
this afternoon through mid evening foe the Western Portion of the
SBA Channel. Otherwise winds should remain below SCA for the other
portions through Sunday morning. Otherwise winds will remain
below SCA levels for the inner waters through Sunday. Sunday will
be similar to today except slightly windier across zone PZZ655
from Pt. Mugu to San Mateo Pt. There is a 60% that SCA will be
needed once again for the SBA Inner waters Western Portion Monday
afternoon.

A short-period west to northwest swell with a period around 6
seconds could impact the coastal waters between Monday and
Wednesday. A mix of short-period seas and/or winds could develop
across the entire coastal waters into midweek next week.

Otherwise, a 2-3 foot south swell with a 16-17 second period will
last through today and may pose a risk for breaking waves
nearshore. People boating or kayaking near shore should use extra
caution.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect until 9 PM PDT Sunday for zones
      38-52>54. (See LAXNPWLOX).
     Beach Hazards Statement in effect through this evening for
      zones 40-41-87. (See LAXCFWLOX).
     Excessive Heat Warning in effect until 9 PM PDT Sunday for
      zone 59. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 9
      PM PDT this evening for zones 645-650. (See LAXMWWLOX).
     Small Craft Advisory in effect from 3 PM this afternoon to 3
      AM PDT Monday for zone 670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Monday for
      zones 673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(MON-FRI)
No significant hazards expected.

&&

$$

PUBLIC...Rorke
AVIATION...Rorke
MARINE...Kaplan
SYNOPSIS...Hall

weather.gov/losangeles



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.