Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
303 am PDT Thursday Jul 28 2016
fair and hot weather will continue today. An increase in monsoonal moisture
this weekend will increase the chance of showers and thunderstorms
in the mountains and deserts each afternoon and evening. It will
also be slightly cooler this weekend into early next week.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Light onshore gradients this morning with the San Diego to daggettgradient
running almost 5 mb, this is trending a bit up as would be
expected as some troughing develops along the coast. Coastal
stratus is also beginning to fill in attm, a bit more coverage
than 24 hours ago.
The marine layer will get a little better hold today, and we
expect some slight but welcome cooling for the coast and western
valleys as a result.
Upper level ridging will still be the dominant player inland,
especially for the mountains and deserts, where temperatures will
be as hot as yesterday, and even a degree or two hotter in a few
spots as the upper level height pattern really is not expected to
change much today compared to yesterday. The heat advisory will
remain in place through this evening for the very hot weather in
the deserts with temperatures again expected to be up to 10
degrees above normal.
Friday will be a transition day as heights begin to fall across
all areas. Return monsoonal moisture will begin to encroach on our
area as well, bringing a slight chance for afternoon and evening
convection. Monsoonal moisture will make a more noteworthy push
Sunday and Monday, with a plume of nearly 2" precipitable water airmass riding
north along the Baja Coast and also across the Sonoran Desert.
This airmass should be capable of generating heavy rainfall and
possible flooding in the deserts and mountains on Sunday and/or
Convection chances still look decent for Tuesday, then a
decreasing threat for convection by mid next week as a weak upper
level trough approaches the California coast, and squashes our
moist airmass to the east. Temperatures are likely to remain near
normal mid next week with more comfortable relative humidity.
280930z...patchy stratus continuing to form along the coast with
bases 800-1200 ft msl, reaching kcrq by 12z. Low confidence in cigs
at ksna. Local vis 2-4 sm possible where status nears higher coastal
terrain. Expect clearing by 16z. Patchy stratus developing late this
evening and spreading locally 10-15 mi inland overnight. Little
change in cig heights expected.
Valleys/mountains/deserts...few-sct clouds above 20000 feet and
unrestricted vis through Fri morning. Cumulus clouds will form over
the mountain crests this afternoon, dissipating by sunset.
no hazardous marine weather is expected through Monday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...heat advisory until 8 PM PDT this evening for apple and Lucerne
valleys-Coachella Valley-San Diego County deserts.