Scientific Forecaster Discussion
Southwest California area forecast discussion
National Weather Service Los Angeles/Oxnard California
330 am PDT Sat Aug 1 2015
Night through morning low clouds will persist at the coast with
mostly clear skies over the rest of the area. Temperatures will be
near normal through next week.
Short term (today-tue)... marine layer is 1300 feet deep and is
capped by a fairly strong inversion. The onshore push to kdag is
about three mb which is similar to last night but there is a 1.5 mb
offshore trend (which has resulted in only weak onshore flow) from
kbfl. By dawn marine layer stratus has filled into most coasts and
valleys and by dawn only the Santa Clarita valley will be free of low
clouds. The flow aloft has turned to the south-southwest and has effectively
shut off the monsoon flow. Precipitable waters have been falling steadily. While
there is a very small chance of a mountain thunderstorm this afternoon it is not
great enough to mention. Maximum temperatures will be right at normal levels.
Very little change in any of the synoptic parameters sun through
Tuesday except the the upper flow becomes even more SW. The northwest flow
does increase across the waters west of sba County and this will
bring a weak sundowner to the Gaviota region each night. This little
sundowner will also limit but not eliminate the stratus for the sba
South Coast. Maximum temperatures will cool just a touch as heights fall a few dm.
Long term (wed-fri)... the ec and the GFS disagree in the long term
with the GFS slowly bringing a weak ridge into the area while the ec
forecasts a weak trough and then at the end of the period it shuttles
in a dry upper low. Heights are really about the same Wednesday and Thursday so in
reality either model will not produce that different a forecast. If the ec
is correct there will be a little more clouds than forecast and it will
be cooler than currently indicated. Went with a persistence forecast
for Friday...but if the ec verifies there will be a much deeper
marine layer and it will be quite a bit cooler than forecast.
The marine layer at klax at 0800z is 1300 feet deep and the
inversion top is at 2200 feet with a temperature of 24 degrees c.
Low-end Small Craft Advisory conditions are expected from Point
Conception to south of San Nicolas Island through early Saturday
morning...with northwest winds gusting up to 25 knots over the
waters near/west of The Channel islands southward to San Nicolas
Island. The Small Craft Advisory winds may continue Saturday morning but are more
likely Saturday afternoon and evening. There is a chance of Small Craft Advisory
conditions in the Santa Barbara basin Saturday afternoon through
early Sunday morning.
Small Craft Advisory (see laxmwwlox).