Scientific Forecaster Discussion
Southwest California area forecast discussion
National Weather Service Los Angeles/Oxnard California
435 am PDT sun Aug 2 2015
..updated aviation discussion...
A trough of low pressure off the coast and a ridge of high pressure
over The Four Corners region will result in near normal temperatures
in most locations through next week...along with night through
morning low clouds and fog west of the mountains. Slight cooling is
possible by late next week as low pressure off the coast moves east.
Short term (today-wed)... the marine layer this morning is 1400
feet deep and is capped by a moderate inversion. Gradients to the
east are similar to ydy but there is a 1 mb offshore trend from the
north. There is no eddy tonight and the marine layer stratus south
of Point Conception is having a hard time getting started. The clear
skies are allowing decent radiational cooling and its more likely
than not that stratus clouds will develop over the next few hours.
There is nothing to keep the low clouds around so look for very good
clearing by middle or late morning. Maximum temperatures will be similar to ydy
and right around seasonal norms. SW flow aloft will keep the
atmosphere dry and there is no threat of convection today.
Little to no change in the synoptic pattern through Wednesday with a
large broad ridge over the desert SW and a weak trough off of the West
Coast. The flow overhead will be from the SW which is dry and the
threat of afternoon convection will be near zero. There will be a
little sundowner each evening across the sba South Coast with the
strongest winds near Gaviota. These winds will keep the South Coast
stratus free....otherwise there will be late night through middle
morning low clouds. Maximum and min temperatures will exhibit only minor day to
Long term (thu-sat)... an weak and dry upper low approaches the
area Thursday but not in time to affect the weather. Perhaps a
little pop up ridge ahead of it will raise the inland temperatures a degree
The upper low moves over the area Friday and Sat. It is not a rain
maker...perhaps a drizzle maker. Its main effect will be to increase
the marine layer and night through morning stratus should cover all
the coasts and most of the valleys. The deeper marine layer and lower
heights will kick off a cooling trend.
At 0816z...the marine inversion at klax was based at 1500 feet. The
top of the inversion was 3400 feet with a temperature of 26 degrees
Overall...moderate confidence in 12z taf package. Stratus entrenched
along central coast...and trying to organize south of Point
Conception. MVFR/IFR ceilings will continue over central coast until
late morning...with MVFR/IFR possible this morning across Ventura
and lax coasts. VFR conds all sites this afternoon/evening...then
stratus should return to most coastal areas overnight.
Klax...moderate confidence in 12z taf. There is a 30% chance that
ceiling restriction will not develop around 13z forecast time. For
tonight...high confidence in return of stratus...but low confidence
in timing (+/- 3 hours of current 08z forecast) and flight category
(a 50% chance of IFR ceilings developing).
Kbur...moderate confidence in 12z taf. There is a 30% chance of IFR
ceilings 13z-17z this morning...and again tonight after 09z.
For the outer waters...high confidence in Small Craft Advisory conditions continuing
through tonight. For Monday through Wednesday...moderate confidence
in winds remaining at Small Craft Advisory levels.
For the inner waters...moderate confidence in Small Craft Advisory conditions
developing today and continuing through tonight across the western
Santa Barbara Channel as well as the waters off the San Luis Obispo
County coast. For these areas...there will be a good chance of Small Craft Advisory
conditions developing afternoon/evening Monday through Wednesday.
Elsewhere across the inner waters...moderate to high confidence in
winds remaining below Small Craft Advisory levels.
Small Craft Advisory (see laxmwwlox).