Area Forecast Discussion
Issued by NWS San Diego, CA
FXUS66 KSGX 241115
AREA FORECAST DISCUSSION
National Weather Service San Diego CA
415 AM PDT SUN JUL 24 2016
The cooling that began Saturday will continue today with the
greatest cooling in the valleys. Slowly warmer inland for Tuesday
through Thursday with some mid and high clouds at times and some
afternoon clouds over the mountains. A little cooler inland for
Friday through next weekend with an influx of monsoonal moisture
bringing a slight chance of afternoon thunderstorms near the
mountains. Areas of night and morning coastal low clouds and fog
will spread locally into the western valleys at times.
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
High pressure aloft will weaken slightly through Monday...
strengthen slightly for Tuesday through Thursday...then weaken
into next weekend as a trough of low pressure develops near the
The cooling that began Saturday as a result of weakening high
pressure aloft and a coastal eddy will continue for most areas
today with the greatest cooling in the valleys.
The circulation center of a coastal eddy has moved far enough
westward...now to the southwest of San Nicolas Island...such that
the most widespread stratus coverage is mostly beyond the offshore
islands with patchier coverage toward the coast with not much
inland spread of the stratus.
Satellite imagery and lightning detection data shows a large
convective complex over northwest Mexico. The GFS initializes this
reasonably well and takes the bulk of the mid and high level
moisture westward across northern Baja through tonight...possibly
just grazing far southern California. The vertical distribution of
this moisture is less than optimal for convective development in
Southern California with most of it 600 mb and above and the bulk
of it from 500 to 300 mb.
An influx of monsoonal moisture for late in the week could be
more favorably distributed for afternoon convection over the
mountains...extending down to around 700 mb. With the developing
trough of low pressure near the West Coast for next weekend...
drier southwest flow aloft should not be too far away to the
240900Z...Coast...Areas of stratus will continue this morning near
the coast and up to about 15 miles inland. Bases will be 500-900 ft
MSL with tops to 1300 ft MSL. Vis restrictions 1-3 SM over the
higher coastal terrain and near the coast, possibly including the
San Diego County mesas, VCNTY KCRQ, KMYF and KSDM. Most areas will
clear out between 16Z-18Z this morning although a few patches BKN
conditions possibly continuing near the beaches through this
afternoon. Coastal stratus will likely reform this evening with
bases a bit higher than this morning, more widespread, and spreading
up to 20 SM inland overnight through early Monday morning.
Valleys/Mountains/Deserts...Some smoke will occur in San Bernardino
County from the Sand Fire of LA County, but most vis will remain
above 5 SM. Otherwise, increasing clouds above 15000 ft MSL with
unrestricted vis will continue through this evening.
No hazardous marine weather is expected through Thursday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
CA...Heat Advisory until 8 PM PDT this evening for Apple and Lucerne
Valleys-Coachella Valley-Riverside County Mountains-San
Bernardino County Mountains-San Bernardino and Riverside
County Valleys-The Inland Empire-San Diego County Deserts-
San Diego County Mountains-San Diego County Valleys-San
Gorgonio Pass Near Banning.