Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
200 am PDT Tuesday Sep 1 2015
a trough of low pressure along the West Coast will continue to bring
fair and cooler weather this week featuring night and morning
coastal clouds extending into the valleys. Brisk onshore flow will
bring locally gusty winds to the Desert Mountain slopes during the
late afternoons and evenings. The trough of low pressure will weaken
a bit during the Holiday weekend...bringing a little warmer weather
by Labor Day.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Coastal low clouds moved into the southern inland Empire rather
smoothly overnight as a decent coastal eddy spins off the coast.
Most of the valleys will become cloudy by sunrise. The clouds will
clear by late morning...but variable high clouds will occasionally
filter the sunshine today through Wednesday. A low pressure trough
will remain rather stationary along the West Coast with little
variation for the rest of the week. So expect a very similar marine
layer depth and extent of coastal clouds during the nights and
mornings. Maximum temperatures will be cooler than average during this
time...but clouds and a really warm sea surface will keep min temperatures
rather high near the coast. The onshore pressure gradient will be
sufficient to produce brisk westerly winds through the usual pockets
of mountain passes and adjacent deserts. Gusts could exceed 40 miles per hour
at the top spots such as Whitewater each evening. On Sunday and
Monday the trough retreats a little allowing a high pressure ridge
to strengthen over the southwest. This will bring a modest warming
trend next week and less extensive coastal clouds for the Holiday.
Any moisture that could bring rain stays away from Southern
California despite a busy tropical season way down south.
010830z...coast/valleys...widespread low clouds with bases 1700-2000
feet mean sea level and tops near 2300 feet mean sea level will continue to spead inland
through 13z this morning. Low clouds have already reached portions
of the inland Empire...including kont. Minor visible restrictions of 4-6
sm with br will be possible at times between 10z and 18z. Otherwise
visible below 3 sm will be limited to areas where low clouds and terrain
intersect. Low clouds are expect to clear to the coast between 17z
and 18z...leaving mosly clear skies this afternoon. Low clouds with
bases 1800-2200 feet mean sea level and tops to 2700 feet mean sea level will begin returning
to coastal taf sites between 01z answer 03z Wednesday.
Mtns/deserts...sky clear with unrestricted visible through Tuesday night.
130 am...no hazardous marine weather is expected through Saturday.
130 am...south swells from cyclones over the tropical east Pacific
will continue to bring elevated surf and a high rip current risk to
local beaches through early Thursday. Highest surf will occur today
and Wednesday with widespread 3-4 feet surf and local sets to 6 feet
along southwest facing beaches. Lower surf heights and weaker rip
currents are expected late Thursday into early Saturday...before a
long period south swell arrives early next week.