Scientific Forecaster Discussion
Southwest California area forecast discussion
National Weather Service Los Angeles/Oxnard California
930 am PDT Sat Aug 1 2015
onshore flow associated with weak low pressure off the
coast will persist into next week. This will result in just below
normal temperatures across the area with overnight to morning clouds
and patchy fog for the coast and adjacent valleys.
Short term (rest of today-tue)...what we get today is what we'll
see through the forecast period since our upper flow pattern changes
little if any through into next week. The 1300 feet or so marine layer
has brought the stratus into most of the nearby valleys...although
the sba South Coast has had trouble filling in so far. This will all
burn off on a similar schedule to yesterday. Meanwhile the monsoon
moisture has fully moved off to the east to bring precipitable water
values back down to normal for this time of year...maybe not even
enough for afternoon mountain cumulus. Models indicating the marine
layer will shrink a bit tonight through Monday night so overnight
stratus may not penetrate as far inland as this morning and may
clear a little faster through the morning. High temperatures will be just
below normal in most spots and slightly above normal some mountain
areas. Wind-wise we should see some gusty evening sundowner winds
sba South Coast and the usual afternoon gusty southwesterly winds in
the Antelope Valley.
Forecast looks good with no changes needed.
***From previous discussion***
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 was 1300 feet deep. The inversion
top was at 2200 feet with a temperature of 24 degrees c.
Widespread stratus in all coastal and most valley areas this
morning. Conds were generally IFR to LIFR...except locally MVFR
across coastal sections of l.A. County. Expect somewhat slower
clearing today...with clearing by late morning in the valleys...and
by early afternoon across the coastal plain.
Locally gusty northwest to north winds are expected across southern sba County this
evening...mainly below passes and canyons...and there may be some
local low level wind shear and MDT uddf. Expect widespread low clouds again in
coastal and most valleys areas tonight...with generally IFR conds
Klax...low to moderate confidence in the taf. There is a 20 to 30
percent chance that ceilings will drop into the IFR category at times
between 12z and 16z. There is a 20 percent chance that ceilings will not
scatter out until at least 22z.
Kbur...moderate to high confidence in the 12z taf. There is a 20
percent chance that ceilings will not scatter out until at least 19z.
Small Craft Advisory conditions are likely from Point Conception to
south of San Nicolas Island this afternoon through Sunday afternoon
and likely Sunday afternoon through the remainder of the period
(wed). 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
Sunday afternoon and each afternoon Monday through Wednesday.
Small Craft Advisory (see laxmwwlox).