Scientific Forecaster Discussion
Southwest California area forecast discussion...updated
National Weather Service Los Angeles/Oxnard California
1040 PM PDT Friday may 29 2015
Updated aviation discussion
Above normal temperatures are expected for inland areas through the
weekend as high pressure moves overhead. Temperatures will return to
near normal next week as a moisture starved frontal system
approaches late Sunday...then a broad trough of low pressure
develops. There is a good chance of night through morning low clouds
and fog for coastal areas and some valley areas through next week.
Short term (tonight-mon)...fair skies with some hi clouds
prevailed for most areas early this evening. There were also some
low clouds along the central coast and from the vtu County coast to
the l.A. County coast from Malibu to Palos verdes. The marine
inversion was around 1100 feet deep at lax this evening. The low
clouds are expected to expand along all coastal areas overnight and
move inland to some of the adjacent valleys...with mostly clear skies
elsewhere. Some low clouds and fog are also expected to develop in
the Salinas River Valley late tonight. Otherwise...mostly clear
skies can be expected. Gusty S to west winds from the l.A. County mountains
to the Antelope Valley this evening will diminish overnight.
An upper level ridge over Southern California this evening will remain over the
area through Sat. The upper ridge will slowly weaken Sat night and sun
as an upper level trough approaches the California coast from the east Pacific. The
upper trough will move into California from later Sun night through Monday.
The may gray marine layer pattern will continue for most coastal
areas into some of the adjacent valleys through Monday...with night and
morning low clouds and fog persisting...although a few coastal areas may
have lingering low clouds well into the afternoon. Otherwise...
mostly clear skies will prevail across the forecast area through the
period. Breezy onshore winds can be expected each afternoon and
early evening during the period...although gusty winds are expected in
the l.A. County mountains and in the Antelope Valley thanks to decent
Temperatures away from the coast are expected to be rather warm again on
Sat with highs well above normal into the lower 90s for the warmest
valleys. Temperatures will then cool slightly for sun but still be a few
degrees above normal. For Monday...temperatures will cool to near normal to
slightly above normal. Highs for the immediate coast will remain near
normal for the most part through Monday.
***From previous discussion***
Long term (tue-fri)...both the GFS and European model (ecmwf) are indicating a
persistent upper trough pattern across California through most of
the week. Night and morning low clouds and fog will be prevalent
across most coastal and valley areas along with cooler than normal
temperatures through the period. Not expecting any precipitation...
but cant rule out some patchy drizzle during night and morning
hours. Breezy conditions continuing across mountains and deserts
during extended period due to strengthening onshore flow.
At 2341z the marine layer depth at klax was around 800 feet.
The top of the inversion was 2700 feet with a temperature of
23 degrees celsius.
Expect stratus with generally IFR to LIFR conds across the coastal
plain overnight...likely pushing into the San Gabriel...Santa Ynez
and Salinas valleys. Conds may improve to MVFR across coastal
sections of l.A. County after 14z. There is a chance that clouds
could push into the San Fernando Valley as well. Expect fairly quick
burnoff of the low clouds Sat...except clouds may linger at the
beaches S of pt Conception into the afternoon.
Klax...moderate confidence in the 06z taf. There is a 20 percent
chance of dense fog with visibilities 1/4 mile or less between 07z and
12z. There is a 20 percent chance that IFR conds will linger through
Kbur...moderate confidence in the 06z taf. There is a 30 percent
chance of IFR to LIFR ceilings between 10z and 17z.&&
For the outer waters...moderate confidence that northwest Small Craft Advisory winds
will continue through tonight. For the weekend...northwest winds
expected to be generally 10 to 20 knots over the outer waters...
increasing to Small Craft Advisory levels late Monday through Wednesday.
Across the inner waters...high confidence winds will remain below
Small Craft Advisory levels through Monday.
Small Craft Advisory (see laxmwwlox).