Scientific Forecaster Discussion
fxus66 ksgx 232035
Area forecast discussion
National Weather Service San Diego California
135 PM PDT Tue Jul 23 2019
monsoon flow from the southeast will continue to bring moisture
into Southern California through Thursday. This will produce
scattered thunderstorms in the mountains and deserts each day from
late morning through early evening. Isolated to scattered showers
and thunderstorms will also be possible west of the mountains
during the nights and mornings through Thursday. A drying trend
begins Friday and continues through the weekend, with increasing
temperatures inland. Monsoon moisture may return for the early to
middle part of next week.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
The upper level high remains over the 4-corners area and continues
to provide monsoon moisture to socal in southeast flow aloft. The
upper-level feature that brought organized showers/tstms to the
region this morning has moved to the north but a few light showers
continue to move northward across socal. In its wake, this
disturbance has left an area of subsidence over socal which, along
with the cloud cover from earlier, has delayed the initiation of
tstms over the mtns this afternoon. However a cluster of tstms
has developed over the mtns of baja about 15-20 miles south of the
border and high resolution models continue to indicate the
development of afternoon tstms over our local mtns. Any tstms that
develop over the mtns this afternoon will have the potential to
produce gusty and erratic winds, hail of varying size, and locally
heavy rainfall which could lead to flash flooding.
From previous discussion...
the center of the 4-corners high will drift to the southwest through
Saturday. This will bring little or no changes for socal weather
on Wed and Thu. Moist southeast flow will continue, with good
chances for afternoon tstms in the mtns and deserts as well as
chances for nocturnal light showers/tstms across the region. The
moist and cloudy conditions will continue to mitigate daytime
For Friday and Saturday...as the 4-corners high continues to drift
to the southwest, the moisture becomes displaced farther south and
the influx of moisture into socal decreases. The resulting drier
and more stable conditions will significantly reduce the chances
for showers/tstms and also allow for higher daytime temperatures
inland...especially in the lower deserts where temps could be 5
degrees above seasonal averages.
For Sunday through early next week...the center of the high
pressure is expected to migrate northward again with slight
weakening of the high pressure as well. This should bring a return
of monsoonal moisture for the early to middle part of next week.
232000z...coast/valleys...mostly clear with high clouds at or above 10000 feet
mean sea level. In the valleys, scattered-bkn040-070cb for eastern portions of the
valleys with -shra and thunderstorms in the vicinity possible at times. Ts/rain showers activity
diminishing after 01z. Patchy stratus on the coast overnight, with
brief periods of ceilings with bases near 1000 feet mean sea level possible 13-16z at
ksan/kcrq/ksan, although confidence is low-mod. Low confidence in
areas of -shra developing Wednesday morning, mostly in the valleys
and in South Dakota County.
Mountains/deserts...variable clouds, mostly bkn040-070, with areas
of thunderstorms and rain most prominent over the mtns through 01z, with decreasing
coverage this evening and overnight. Gusty surface winds, strong uddfts and
frequent lightning will be possible near storms. Otherwise, scattered-broken
high clouds at or above 15000 feet mean sea level through Wednesday.
no hazardous marine weather is expected through Sunday.
Skywarn activation is not requested at this time. However weather
spotters are encouraged to report significant weather conditions.