Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
822 PM PDT Monday Jul 25 2016
partly cloudy skies through Tuesday as a wave of humid air moves
through the region. There is a slight chance of showers and
thunderstorms Tuesday afternoon, mainly in the mountains. High
pressure will bring slightly warmer weather this week with patchy
coastal clouds nights and mornings. For Friday through next weekend,
an influx of monsoonal moisture will bring cooling, and another
chance of afternoon thunderstorms, mainly near the mountains.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
The weak disturbance that brought clouds and sprinkles across the
region today is passing to the northwest this evening. Skies have cleared
most areas, including much of the California bight. The 00z Miramar sounding
had a deep moist layer between 15k and 30k feet with a precipitable water of 1.62
inch. A weak inversion was based near 1300 ft, and unlike the past
few days, south winds have been replaced with northwest winds below 5k feet.
Satellite derived precipitable water indicated a rich moisture environment with
pws 1.5-2.0 inch from the Gulf of CA, up across socal.
The only change to the forecast this evening was to add the slight
chance of thunderstorms to the mountain areas on Tuesday afternoon.
Another weak disturbance is forecast to traverse socal on Tue, and
given the high precipitable water in place, it could set off isolated thunderstorms,
provided there is enough sun to heat the mountain tops. Dcape values
are around 1000 j/kg with a fairly deep dry layer below 10k ft, so
there is a microburst and dry lightning threat. For most of the area
however, expect another dry and warm day under partly cloudy skies.
The center of the subtropical ridge was near The Four Corners region
of the SW this evening. The center is forecast to drift northwest and
strengthen slightly through Wednesday. This should trend daytime
temperatures upward and dry things out a bit until late in the week,
when the high is forecast to weaken. Another surge of monsoonal
moisture may arrive over the weekend when there is another chance of
thunder in the forecast. Then, cooler through early next week as
another weak trough develops along the West Coast.
260330z...coast/valleys...areas of broken-overcast stratus will likely
develop between 07z and 11z within 15 miles of the coast, with cigs
for at least a few hours at ksan, kcrq and ksna. Bases will be 800-
1100 ft mean sea level with tops to 1300 ft mean sea level. Local vis below 3 miles will
occur over higher coastal terrain 10z-15z. Most areas will clear 15z-
16z Tue. Otherwise, occasional scattered-broken clouds above 15000 ft mean sea level
will prevail through Tue.
Mtns/deserts...there is a slight chance of thunderstorms over the
mountains Tue afternoon with bases 9000 ft mean sea level and tops to 35000 ft
msl, along with local surface gusts to 40 knots and low level wind shear. Otherwise,
occasional scattered-broken clouds above 15000 ft mean sea level and unrestricted vis
will prevail through Tue.
no hazardous marine weather is expected through Saturday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.