Area Forecast Discussion
Issued by NWS San Diego, CA
FXUS66 KSGX 262049
AREA FORECAST DISCUSSION
National Weather Service San Diego CA
149 PM PDT TUE JUL 26 2016
Continued warm inland today with a chance of afternoon showers
and thunderstorms over the mountains and desert slopes, but less
humid west of the mountains. Gradually warmer through Thursday or
Friday, then minor cooling into early next week. A greater influx
of monsoonal moisture will bring a slight chance of afternoon and
early evening thunderstorms in the mountains and deserts for
Friday through early next week.
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
This afternoon...a shallow marine layer maintains areas of low
clouds at the immediate coast of San Diego county. Temperatures
are several degrees higher than this time yesterday, mostly due to
the lack of cloud cover. Cumulus buildups have developed over the
mtns, but so far no significant echoes have been detected by
radar. The moisture from the collapsed MCS over the Sonora desert
is tracking west and it appears that the bulk of it will remain to
our south. At the same time, mid-level clouds are moving over the
San Bernardino mtns from the east. In spite of the available
moisture, conditions may not be unstable enough to support
widespread deep convection this afternoon/evening. Although,
isolated showers/tstms remain a threat.
From previous discussion...
Gradually warmer through Fri as the upper- level pattern shifts,
with a trough deepening over the eastern U.S. and the ridge
amplifying over the western U.S. This will bring less monsoonal
moisture with a more stable atmosphere through Thu, reducing the
chances for afternoon/evening showers and tstms. The marine layer
will remain very shallow with night and morning low clouds limited
to the immediate coast.
For the weekend into early next week...a trough of low pressure
will deepen over the west coast, weakening the upper ridge and
bringing generally lower temperatures and a little deeper marine
layer. As the upper high repositions itself, monsoonal flow will
once again bring more moisture into the region, resulting in
chances for afternoon/evening showers and tstms over the mtns and
262010Z...Coast/Valleys...Low clouds, with bases 600-900 ft MSL and
tops around 1000 ft MSL, will linger along the immediate San Diego
County coast through this afternoon. VFR conditions will continue
this afternoon elsewhere. BKN/OVC stratus will redevelop along
portions of the coast and around 15 sm inland late tonight with
bases 700-1000 ft MSL and tops 1300 ft MSL. Vis of 2-4 sm BR is
possible where low clouds near higher terrain.
Mtns/Deserts...Isolated TSRA are possible over the mountains this
afternoon with bases 9K ft MSL and tops to 35K ft MSL, along with
local surface gusts to 40 knots and LLWS. Otherwise, occasional SCT-
BKN clouds at/above 15K ft MSL and unrestricted vis through Wed
No hazardous marine weather is expected through Saturday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.