Area Forecast Discussion
Issued by NWS San Diego, CA
FXUS66 KSGX 251222
Area Forecast Discussion
National Weather Service San Diego CA
422 AM PST Sat Feb 25 2017
Continued cool today with patchy frost in the inland valleys early
this morning. For late tonight through Monday night...a pair of low
pressure systems from the northwest will bring cooling...periods
of mainly light precipitation...and periods of strong gusty west
winds on the desert slopes of the mountains. Slightly warmer for
Tuesday. Then dry with a warming trend for Wednesday into next
weekend with periods of weak offshore flow.
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
.SHORT TERM (Today through Monday night)...
Today will be another cool day with patchy frost in portions of
the inland valleys early this morning. The first in a pair of low
pressure systems from the northwest will move through Southern
California late tonight and early Sunday with a second for tonight
and Monday. The first round of mainly light precipitation for
areas along and west of the mountains and deserts is expected for
late tonight into Sunday morning with precipitation spreading
southward across the area.
A second round of precipitation is expected for Sunday night into
Monday with showers lingering into Monday night. For this second
round of precipitation...a trough of low pressure from the
northwest will tap a plume of subtropical moisture extending into
northern Baja. The more significant precipitation is expected
across northern Baja with lighter precipitation extending into
southern portions of Southern California with the greatest
precipitation amounts for Southern California expected across San
For this second round of precipitation...rainfall amounts have
been increased somewhat for San Diego County from one third to
locally one half inch near the coast to one half to one inch in
the mountains with less than one tenth inch in the deserts.
Snow levels will fluctuate around 5000 feet.
There will also be periods of gusty west winds...strongest near
the mountain ridge tops onto the desert slopes of the mountains.
The first is expected for tonight. The second is expected for
Sunday night into Monday evening. This second round is expected to
be a little stronger and more widespread.
High temperatures for Sunday and Monday are expected to be around
5 degrees below average near the coast...to 10 to 15 degrees below
average for areas farther inland.
.LONG TERM (Tuesday through Friday)...
Slightly warmer for Tuesday with northwest flow aloft. For
Wednesday through Friday...high pressure aloft near the
California coast and surface high pressure over the Great Basin
will bring dry weather with a warming trend with periods of weak
251000Z...Mostly clear with unrestricted vis this morning. FEW-SCT
clouds 3000-5000 ft MSL developing west of the mountains after 18Z,
becoming BKN-OVC after 11/00Z. Bases lowering to 2500-3500 ft MSL
overnight. Coastal mountain slopes becoming obscured in clouds/fog
tonight. Otherwise increasing clouds AOA 10000 ft MSL and
unrestricted vis through Sunday.
A weak storm will bring occasional showers and winds gusting to near
20 kt at times Sunday and Monday. Otherwise no hazardous marine
weather is expected through Thursday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
CA...Wind Advisory from 4 PM this afternoon to 10 PM PST Monday for
Riverside County Mountains-San Bernardino County Mountains-
San Diego County Mountains-San Gorgonio Pass Near Banning.
Frost Advisory until 8 AM PST this morning for San Bernardino
and Riverside County Valleys-The Inland Empire-San Diego