Area Forecast Discussion
Issued by NWS Los Angeles, CA
FXUS66 KLOX 281730
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1030 AM PDT THU JUL 28 2016
A high will bring above normal temperatures inland this week.
Over the weekend the monsoonal moisture will arrive to
bring a slight chance showers and thunderstorms to Ventura and Los
Angeles county mountains and deserts. Then early next week the
onshore flow will increase for more low clouds and a cooling trend.
Solid marine lyr north of Pt Conception but just a few patches to
the south. Otherwise, another sunny and warm day across the area
with highs similar to maybe a degree or two warmer for inland
areas. Air mass slightly unstable again today but moisture too
high up to pose much of a problem today or tomorrow so will keep
thunderstorms out of the forecast. 12z models not much different
from previous runs so the afternoon forecast probably won`t look
much different than it currently does.
***From previous discussion***
Sprawling upper high over the Great Basin will move little through
Saturday. Expect night through morning low clouds and fog to
remain confined to the coastal plain, mainly within a few miles
of the beaches tonight and Friday night. A few buildups are
expected in the mountains and Antelope Valley Fri afternoon.
Models actually show a slight bump up in 950 mb temps on Fri, so
highs could be up slightly, especially away from the coast.
Somewhat better moisture moving into the region on Sat warrants
a slight chance of tstms for the mtns of L.A. and VTU County
mountains and the Antelope Valley Sat afternoon and evening, but
latest model runs are looking less impressive. With the upper high
weakening some on Sat, and with onshore flow increasing, expect
a few degrees of cooling to all area on Sat.
The upper high will weaken a bit or on Sunday, so a couple
more degrees of cooling is expected in most areas. Weak sely flow
aloft will cont to justify a slight chance of showers/tstms
in the mtns of L.A. and VTU counties and the Antelope Valley
Sunday afternoon and evening. Night through morning low clouds
and fog confined to the coastal plain.
There is not much change in the pattern Monday through
Wed, with an upper high centered near the Four Corners
region. Night through morning low clouds and fog should remain
confined to the coastal plain, but it is not out of the question
that some clouds could spread into the lower valleys. Max temps
should generally be near normal through the period. The flow will
remain somewhat favorable for ocnl surges of monsoonal moisture
into the region during that time, but best chances should remain
s and e of the region.
At 18z, the marine layer was around 1000 feet deep at KLAX. The
top of the inversion was near 4000 feet with a temperature around
27 degrees celsius.
Satellite imagery showing good clearing for areas south of Point
Conception this afternoon, with ifr cigs lingering near some of
the beach areas north of Point Conception. Shallow marine layer
around 1000 feet will persist across the region tonight, producing
ifr/lifr cigs for portions of the coast. High probability of cigs
will be for KSMX and KSBP where there is fairly high probability
of lifr cigs and a 20 percent chance of vlifr cigs. Low confidence
of cigs for coastal sites south of Point Conception. A few elevated
cu buildups possible over the San Gabriel Mtns and Ventura County
Mtns after 20z.
KLAX...Low confidence with return of IFR cigs tonight into Friday
morning. There is a 30 percent chance that VFR conditions could
persist through entire forecast period.
KBUR...High confidence in VFR conditions through forecast period.
High confidence in the current forecast through Saturday. The
marine layer inversion remains relatively shallow which will
result in areas of dense fog mainly north of Point Conception with
only patchy fog for areas to the south. Weak to locally moderate
northwest winds will kick up each afternoon near the islands and
across the outer waters, with gusts of 20 to 25 kts through the
early evening hours. A Small Craft Advisory is in effect for this
afternoon and evening for the Southern Outer Waters.
A small but long period southerly swell will develop Saturday
night through Sunday. Not anticipating any issues.
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 3
AM PDT Friday For zones 673-676. (See LAXMWWLOX).