Scientific Forecaster Discussion
Southwest California area forecast discussion...updated
National Weather Service Los Angeles/Oxnard California
520 am PDT Sat may 30 2015
Updated aviation discussion
Above normal temperatures are expected for inland areas through the
weekend as high pressure persists overhead. Temperatures will return
to near normal or just below next week as the High Breaks down and a
weak frontal system approaches late Sunday into Monday. A broad
trough of low pressure develops early next week. 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 (today-mon)...latest amdar soundings near lax indicated
the marine layer depth around 1000 feet this morning...with a strong
inversion. Latest fog product imagery indicated low clouds filling
in across the coastal areas and will likely reach coastal valleys by
sunrise. With such a strong inversion in place...low clouds should
have a tough time scouring out along the immediate coast of
Ventura...Santa Barbara and San Luis Obispo coast this afternoon. La
County coast should clear out by middle to late morning.
Synoptically...an amplified upper ridge axis which is currently over
the entire West Coast will continue to allow for warmer than normal
temperatures across areas away from the coast. The marine layer will
continue to be around 1000 to 1500 feet deep through Sunday morning.
Today should be the peak of the warmest temperatures for Los
Angeles...Ventura and Santa Barbara counties...while San Luis Obispo
County should see a slight decrease in high temperatures across the
interior locations...including Paso Robles which reached 95
yesterday...but should be closer to 90 today. Expect the warmest
valleys to be in the lower 90s for la/vtu County valleys and the
Lower Mountain elevations...while the Antelope Valley reaches the
middle 90s. Meanwhile...coastal areas will continue to be mild due to
the marine layer influence.
By Sunday...a deeper upper level trough will move into California
allowing for widespread cooling along coastal areas and a few
degrees of cooling for inland areas. Best cooling will occur across
areas north of Point Conception. There will continue to be a few degrees
of widespread cooling on Monday as well as the upper trough will
persist over the region. The marine layer will deepen up bringing
more widespread low clouds and fog to the coastal valleys Sunday
night into Monday morning.
There will be a weak short wave moving across the northern portion
of the forecast area Monday afternoon through early Tuesday. The
marine layer could deepen up to allow for some patchy drizzle for
areas west of the mountains. As the dry front moves through the
region...northerly winds are expected to increase across the usual
wind prone areas including Santa Barbara County mountains...adjacent South
Coast as well well as the I-5 corridor and Antelope Valley with west
to northwest winds. At this time...it looks like winds will remain
below advisory levels. There will be some low clouds banking up
against the northern slopes of the Ventura and Santa Barbara County
mountains Monday night into early Tuesday morning.
Long term (tue-fri)...both the GFS and European model (ecmwf) continue to advertise
the upper level trough to stick around over the eastern Pacific and
California through much of next week. Expect the typical June gloom
pattern with night through morning low clouds along the coast and
coastal valleys through the long term period. Overall...high temperatures
will be a bit cooler than normal. Expect gusty southwest winds
across the Antelope Valley to be a daily afternoon and evening
occurrence during this typical onshore flow regime.
Update on Hurricane Andres...the track of Hurricane Andres will
continue to move slowly north to northwest tracking well west of
Cabo San Lucas. Models downgrade the hurricane to a tropical storm
by early Monday morning. Andres is expected to weaken quickly by
next Monday night. As far as moisture remnants...looks like the
remnant moisture will stay well south of California.
The GFS is also picking up on another tropical disturbance west of
Mexico. If the model is correct... it takes aim towards Cabo San
Lucas around June 7th. It is way to early to bun into this solution.
But people should continue to follow as updates occur throughout
at 12z...the marine layer depth at klax was 1400 feet. The top
of the inversion was at 3100 feet with a temperature of 23 degrees
Stratus with generally IFR to LIFR conds was widespread on the
coastal plain...and in the San Gabriel and Salinas valleys.
IFR to LIFR ceilings will probably push into the San Fernando Valley
for a few hours. Expect fairly quick clearing in the valleys
and across interior sections of the coastal plain...with slower
clearing near the coast. In fact...clouds may linger at the
beaches S of pt Conception into the afternoon. Expect
IFR conds to return to the coastal plain this evening...and to
most valley areas late tonight.
Klax...moderate confidence in the 12z taf. There is a 20 to 30
percent chance that IFR conds will linger through 21z or 22z.
Kbur...moderate confidence in the 12z taf. There is a 20 percent
chance of dense fog with visibilities 1/4 mile or less between 13z and 15z.
Fairly high confidence that winds/seas will remain below Small Craft Advisory levels
across the entire water through Monday. However...occasional Small Craft Advisory level
gusts are possible in the outer waters during the afternoon and
evening hours...especially sun and Monday. There is a good chance of
Small Craft Advisory level winds across the outer waters Monday night or Tuesday through
Local dense fog is expected this morning and possibly again late
tonight and Sunday morning across the Santa Barbara Channel and
the inner waters north of pt Conception.