Area Forecast Discussion
Issued by NWS San Diego, CA
FXUS66 KSGX 310301
AREA FORECAST DISCUSSION
National Weather Service San Diego CA
800 PM PDT TUE AUG 30 2016
High pressure aloft will continue very warm weather just inland
from the coast through Wednesday, then cooler into the Labor day
weekend as a low pressure trough develops over the West Coast.
Gusty westerly winds will develop over the mountains and deserts
during the latter half of the week, along with low relative humidity,
which will increase the wildfire danger in these areas.
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
Satellite imagery shows patchy marine clouds just offshore,
otherwise skies were mostly clear with a smoke layer over portions
of the Inland Empire associated with the Bogart Fire near Banning.
Marine clouds should reform overnight, but be limited to the coastal
strip. Surface pressure gradients showed onshore trends, but
remained weak offshore from NV and 6-7 MBS onshore KSAN to the
lower deserts. Strongest wind gust reports were 25-30 MPH far inland
near the passes.
A coastal eddy has formed and should linger into Wednesday, keeping
coastal areas cooler into Wednesday, while inland areas remain quite
warm. Cooler on Thursday all areas as onshore flow and the marine
From previous discussion...
The high pressure ridge will slowly give way to a fairly robust
trough over the Pacific Northwest, beginning a cooling and drying
trend for the latter half of the week, through the holiday
weekend. However, a thin layer of monsoon moisture will continue
at around mountain top level through Thursday, serving to explain
the cumulus clouds mainly over the mountains each afternoon. The
atmosphere appears too stable to allow for those clouds to produce
any rain. Temperatures will drop below average as the trough
slowly settles over the entire western part of the country and
coastal clouds will be allowed to spread farther inland each night
and morning. High pressure appears to rebound next Tuesday to
start a gradual warming trend.
310345Z...Coast/Valleys...SCT-BKN008-014 along the coast this
evening becoming BKN-OVC007-013 tops 1500 ft through 14Z and
spreading 15 miles inland impacting KSAN, KCRQ and KSNA. Areas of
vis 3-5 miles with local vis AOB 1 mile along higher coastal
terrain/mesas. Confidence in cigs/vis is low to moderate.
Smoke from the Bogart fire near Banning will drift over the Inland
Mountains/Deserts...Some vis restrictions in smoke tonight from the
Bogart Fire near the San Gorgonio Pass. SKC except for some SCT-BKN
clouds AOA 10000 ft msl Wednesday afternoon over the mountains.
No hazardous marine weather is expected through Sunday.
Onshore flow will be increasing on Wednesday and continue moderate
into the Labor Day weekend. Westerly winds of 15 to locally 25 MPH,
with peak gusts of 30 to locally 40 MPH will be likely on some
ridges, desert slopes, and through passes at times starting late
Wednesday and continuing into Friday, while minimum RH falls to
10-15 percent for Friday and Saturday in these areas.
Near critical fire weather conditions will be possible at times in
the onshore wind prone areas late in the week.
Skywarn activation is not requested. However weather spotters are encouraged
to report significant weather conditions.