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Area Forecast Discussion (AFD)

Issued by San Diego, CA (SGX)

                            
000
FXUS66 KSGX 161029
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
329 AM PDT Tue Jul 16 2019

.SYNOPSIS...
Slightly cooler for inland areas today. Low clouds over the
coastal waters will extend into some coastal areas early this
morning with patchy dense fog near higher coastal terrain and the
mesas. A weak trough of low pressure to the north will bring 
greater cooling for Wednesday into the weekend. The marine layer 
will deepen with night and morning coastal low clouds spreading 
into the western valleys for tonight into Wednesday morning and 
into portions of the inland valleys for Thursday into Saturday.
For Sunday through Tuesday, strengthening high pressure will 
bring a warming trend with the marine layer becoming shallower. A 
gradual influx of monsoonal moisture will bring increasing 
humidity for inland areas and a slight chance of afternoon 
thunderstorms near the mountains on Monday and Tuesday.

&&

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

High pressure will weaken as a weak trough of low pressure moves
inland through the western states for today into Wednesday. Today
will be slightly cooler for inland areas with greater cooling
spreading inland for Wednesday and Thursday followed by minor day
to day changes for Friday and Saturday.

The marine layer has decreased in depth to around 1200 feet. 
Early this morning, satellite imagery shows areas of coastal low 
clouds along the Baja coast extending northward into portions of 
the southern California coast. The low clouds will extend locally 
inland into portions of the coastal areas early this morning with 
patchy dense fog near higher coastal terrain and the mesas. 
Satellite imagery also shows a large area of low clouds along the 
California coast from Point Conception northward surging southward
just beyond the California bight. 

The marine layer will begin deepening with night and morning 
coastal low clouds spreading into the western valleys for tonight 
into Wednesday morning and into portions of the inland valleys for
Thursday into Saturday.

For Sunday through Tuesday, high pressure across the central and
southern Rockies into the southwest states will strengthen and
expand. This will bring a warming trend for most areas with the
warming in the lower deserts modulated by influxes of monsoonal
moisture. The marine layer will become shallower with night and
morning coastal low clouds not spreading as far inland. 

There remain differences among the global models with the details
of the influx of monsoonal moisture into southwest California for
Sunday through Tuesday. The models generally show an initial
influx of moisture from the southeast on Sunday with an additional
influx on Monday. There is greater spread beyond Monday on day to
day differences in moisture and its placement. A slight chance of
thunderstorms has been added near the mountains for Monday and 
Tuesday afternoons. 

&&

.AVIATION... 
160900Z...Coast...Prevailing BKN-OVC002-006 with intermittent SCT 
through 16Z, with terminals clearing thereafter. High (80%) 
confidence in periods of VIS 1/2-2SM at coastal terminals through 
16Z. Moderate (50%) confidence in brief periods 1/4SM in FG, most 
likely at KSAN/KCRQ. CIGS redeveloping after 05Z Wed with higher 
bases 700-1100 FT MSL and widespread VIS 2-4SM on mesas and with
higher coastal terrain obscured. 

Valleys/Mountains/Deserts...Brief CIGS may intrude into westernmost 
portions SD County valleys Tuesday night. Otherwise, CLR with 
unrestricted vis through Wed. 

&&

.MARINE... 
No hazardous marine weather through Saturday. 

&&

.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...17
AVIATION/MARINE...Rodriguez