San Diego Weather at Mission Trails, CA

000
FXUS66 KSGX 201034
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
234 AM PST Tue Nov 20 2018

.SYNOPSIS...
A weakening low pressure system moving inland across the area
today will bring some clouds and cooling. For Wednesday night and
Thursday, a trough of low pressure moving inland through
California will bring a period of showers for much of southwestern
California along and west of the mountains and across the high
deserts with much of the precipitation falling from late Wednesday
night into Thursday morning. A second period of lighter showers
is possible for late Friday night into Saturday morning along and
west of the mountains. For Sunday and Monday, high pressure aloft
near the California coast and surface high pressure over the Great
Basin are expected to bring offshore flow and a warming trend
with periods of gusty northeast winds for the mountains and inland
valleys.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

.SHORT TERM (Today through Thursday)...
A weakening low pressure system will move inland across southern
California and northern Baja today. It is not expected to have
much impact other than to bring some clouds and some cooling,
though an isolated sprinkle is not out of the question. Onshore
flow will continue for tonight and Wednesday with greater coverage
of night and morning coastal low clouds and fog possible along
with slow deepening of the marine layer.

For Wednesday night and Thursday, a trough of low pressure and the
associated cold front is expected to bring a period of showers
for much of southwestern California along and west of the
mountains and across the high deserts with much of the
precipitation falling from late Wednesday night into Thursday
morning as the front moves across the area. Some lighter and less
widespread precipitation may precede the front Wednesday evening
into Wednesday night.

Rainfall amounts are expected to range from one tenth to one
quarter inch near the Orange County coast to one half to one inch
in the San Bernardino County mountains with locally greater
amounts. Rainfall amounts are expected to be less farther south
with amounts in San Diego County ranging from around one tenth
inch near the coast to one quarter to one third inch in the
mountains with locally greater amounts. In the deserts, the high
desert areas are expected to receive around one tenth inch with
less than one tench inch in the lower deserts. The snow level will
lower to around 6500 feet for late Wednesday night into Thursday
morning with a few inches of snowfall possible on the higher peaks
in San Bernardino County, mostly above 7000 feet. The forecast
rainfall leans away from the drier GFS and toward a blend of the
QPF from WPC and local higher-resolution models.

&&

.LONG TERM (Friday through Monday)...
A trough of low pressure to the north moving across the Pacific
Northwest on Friday into the Great Basin on Saturday could bring a
a few mostly light showers along and west of the mountains late
Friday night into Saturday morning with the greatest coverage in
San Diego County if they were to occur.

For Sunday and Monday, high pressure aloft near the California
coast and surface high pressure over the Great Basin are expected
to bring offshore flow and a warming trend with periods of weak of
possibly moderate strength gusty northeast winds in the mountains
and inland valleys and below passes and canyons. The forecast
during this period leans toward the ECMWF.

&&

.AVIATION...
201015Z...Coast/Valleys...FEW-SCT low clouds with bases 1000-1500 ft
along the coast this morning. Chances of CIGS at any of the coastal
airports is low. Otherwise local 4-6 SM vis in BR along the coast
and up to 10 mi inland through 15Z. After 15Z, variable clouds AOA
15000 ft MSL and unrestricted vis through the evening. Patchy low
clouds with bases near 1500 ft MSL developing along the coast after
21/03Z and spreading into portions of the valleys overnight.

Mountains/Deserts...Variable clouds AOA 15000 ft MSL and
unrestricted vis through Wed morning.

&&

.MARINE...
No hazardous marine weather is expected through Thursday. Wind gusts
near 20 kt are possible Friday afternoon into Saturday, mainly near
San Clemente island.

&&

.FIRE WEATHER...
Periods of offshore flow with gusty northeast winds and lower
inland humidity are possible for Sunday and Monday, but with low
confidence in the timing and intensity. However, the most likely
intensity would be weak to possibly moderate. Some modification of
the very dry fuels situation is possible from precipitation that
is expected for Wednesday night and Thursday. But offshore winds
and lower inland humidity are expected to bring periods of at
least elevated fire weather conditions for portions of the
mountains and inland valleys for Sunday and Monday.

&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC/FIRE WEATHER...17
AVIATION/MARINE...SS