Small Craft Advisory 68, NWS Los Angeles, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
929 AM PDT Thu May 11 2017

.SYNOPSIS...
A high will build in for night to morning low clouds...fog for the
coast and coastal valleys...otherwise fair inland with normal
temperatures. Breezy winds on Friday and Saturday as a low should
approach. The low may linger into mid week for a deepening marine
layer and around normal temperatures.

&&

.SHORT TERM...(TDY-SAT)

Satellite imagery showing a solid blanket of low clouds across
much of SLO/SBA counties this morning, with 12z Vandenberg
sounding showing a marine layer depth around 3800 feet. For
Ventura and Los Angeles counties, low cloud coverage is greatly
reduced from yesterday at this time, with some low clouds near
the coast. With low level moisture in place, will see increasing
stratocumulus clouds today with daytime heating. With a reduced
marine layer cloud coverage today over Ventura and LA counties,
look for these areas to be warmer today. Look for gusty west
winds across the Antelope Valley today. Wind event still on
track for Friday afternoon through Saturday per latest 12z
NAM model.

*** From previous discussion ***

An upper low will move through the Eastern Pacific toward the Pac
NW tonight and Fri. The wrf suggests that the marine inversion
will lower tonight, and a more traditional marine layer may form,
with areas of night through morning low clouds and fog in most
coastal and valley areas. Skies should become mostly sunny in most
areas by afternoon. Max temps should not change too much on Fri,
except there should be some cooling in the mtns and deserts.

The upper low will move into the Pac NW Fri night and into Nevada
on Sat. N-S Gradients will sharpen late Fri and Fri night, then
remain strong into Sat. Gusty northwest winds will likely reach
advisory levels on the Central Coast Fri afternoon, then advisory
level northwest to north winds are expected Fri night in the Santa
Ynez Range and adjacent south coast of SBA County and through the
Interstate 5 corridor Fri night into Sat morning. Gusty winds may
spill into the valleys of L.A. and eastern VTU Counties Fri night
and early Sat. Winds may also reach advisory levels in the
Antelope Valley late Fri into Fri night. Low clouds will probably
be confined mainly to coastal sections of L.A. County and possibly
the San Gabriel Valley Fri night/Sat morning. Skies should become
sunny in those areas by late Sat morning. Max temps will likely
jump up several degrees on Sat, especially in coastal and valley
areas, where max temps may actually rise to slightly above normal
levels.

.LONG TERM...(SUN-WED)

Another upper low will drop southward into CA Sun, then drift into
the Great Basin by late Mon. Yet then another upper low will drop
into the Pac NW Tue, then drop southward through CA Wed. This
will keep temperatures on the cool side though the middle of next
week. As each system passes to the north and northeast of the
region, they should generate some gusty west to northwest winds
at times. There will probably be a fairly deep marine layer for
much of the time, with areas of night through morning low clouds
and fog in most coastal and valley areas, disrupted at times
by the northwesterly flow. The 06z GFS ids farther west with the
system late Tue and Wed, and some shower activity is a distinct
possibility, especially in the mountains.

&&

.AVIATION...11/1530Z...

At 1530Z, the marine inversion at KLAX was based at 3200 feet. The
top of the inversion was 5500 feet with a temperature of 15
degrees Celsius.

Overall, moderate confidence in 18Z TAF package. For sites north
of Point Conception, MVFR CIGs will continue through mid-afternoon
(although there is a 40% chance that MVFR CIGs will not scatter
out as forecast around 22Z). For tonight, high confidence in
return of MVFR CIGs, but low confidence in timing. For the sites
south of Point Conception, VFR conditions will continue through
this evening. Overnight, high confidence in MVFR CIGs returning,
but low confidence in timing.

KLAX...Moderate confidence in 18Z TAF. High confidence in VFR
conditions through early evening. Overnight, moderate confidence
in return of MVFR CIGs, but low confidence in timing (could be
+/- 4 hours of current 06Z forecast).

KBUR...Moderate confidence in 18Z TAF. High confidence in VFR
conditions through early evening. Overnight, moderate confidence
in return of MVFR CIGs, but low confidence in timing (could be
+/- 4 hours of current 08Z forecast).

&&

.MARINE...11/800 AM...

For the Outer Waters, high confidence in current forecast. Winds
and seas will remain below Small Craft Advisory (SCA) levels
through this afternoon. By tonight, winds will increase to SCA
levels Thursday. On Thursday evening, northwest winds will
increase to SCA levels then increase to Gale force levels on
Friday. The Gale force winds will continue through Monday.

For the Inner Waters, moderate to high confidence in current
forecast. For the waters north of Point Sal, winds and seas will
remain below SCA levels through tonight. On Friday, the winds
will increase to strong SCA levels and remain at SCA levels
through the weekend (with a 50% chance of Gale force conditions
developing this weekend). For the waters south of Point Conception,
winds and seas will remain below SCA levels through tonight. On
Friday, winds will increase with SCA conditions likely through the
weekend, especially across western sections (with a 50% chance of
Gale force winds for the western portion).

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect from 8 PM this evening to 9 AM
      PDT Friday for zones 670-673-676. (See LAXMWWLOX).
     Gale Watch in effect from Friday morning through late Sunday
      night for zones 670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(SAT-WED)
High surf and strong rip currents are possible this weekend
at area beaches. Gusty northwest to north winds will affect
portions of Southwest California Saturday and again during
the middle of next week, bringing elevated fire weather
concerns to the region.

&&

PUBLIC...Gomberg/DB
AVIATION...Thompson
MARINE...Thompson
SYNOPSIS...STu

weather.gov/losangeles