Scientific Forecaster Discussion
Southwest California area forecast discussion
National Weather Service Los Angeles/Oxnard California
1040 am PDT Monday Aug 3 2015
Synopsis... weak high pressure building over the southwest will
bring a slight warm up...then a dry trough of low pressure off the
coast will push east through the area late in the week for a cooling
trend. Temperatures will remain mainly below normal with overnight
to morning coastal clouds and fog persisting into the weekend.
Short term (rest of today-wed)... what overnight stratus that did
form has essentially cleared out for the day...all but in the Long
Beach area. Little change in temperatures today compared to yesterday
although they may be slightly cooler in spots due to some high level
clouds that will push across today in the upper level southwest
flow...these clouds tracing all the way back to blowoff from
Tropical Storm Guillermo east of Hawaii. There will be some periods
today that will be pretty cloudy but overall more sun than clouds.
Not much change expected in the marine layer depth through the short
term and the very slight warm up is still expected into
midweek...now looking like Wednesday will be the relatively warmest
day of the week. But daytime temperatures will still be at or just below
normal even with the
***from previous discussion***
Long term (thu-sun)... a little pop up ridge develops over the
area Thursday ahead of a weak cut off low that moves towards the
coast. This will allow inland temperatures to bump up a little.
The upper low moves over the area Friday and Sat. This is a weak and
dry system and there is no threat of convection. The gentle lift
associated with the low will enhance the marine layer cloud deck and all
coasts and most valleys will be cloud covered. Heights will fall and with
the increased depth of the marine layer there will be good cooling
trend across the board. Some inland warming Saturday as heights rise in
the afternoon in the wake of the upper low.
The warming trend will continue Sunday as heights rebound a little more
and the marine layer shrinks. SW flow holds steady over the area and
there the area will stay monsoon free.
Upper level trough over the eastern Pacific will persist while a middle
level trough of low pressure approaches. Upper level moderate and
relatively moist southwest winds will prevail and middle level light
west winds will become light to moderate southwest after 04/20z.
Weak to moderate onshore pressure gradient through 04/04z and after
04/20z otherwise weak north and onshore gradient. Marine inversion
with a base approximately 1.6kft this morning will differ little
Tuesday morning. Marine cloud field was unorganized this morning and
expect little difference Tuesday morning.
Marine layer at lax at 1500z is 1594 feet deep and the inversion top
is at 3084 feet with a temperature of 24 degrees c.
Klax...chance ceilings 012 between 04/10-04/16z.
Kbur...chance current sky/visibility conditions will persist.
Virtually certain - 95-100%
very likely - 80-95%
likely - 60-80%
chance - 30-60%
very unlikely - 20% or less
Small Craft Advisory conditions with northwest winds and very steep
seas will persist from Point Conception to south of San Nicolas
Island through Wednesday morning. And there is a chance Small Craft Advisory
conditions will exist in the west half of the Santa Barbara basin
and in the vicinity of Santa Cruz Island each afternoon today
Small Craft Advisory (see laxmwwlox).