San Diego Forecast Discussion

FXUS66 KSGX 271955

Area Forecast Discussion
National Weather Service San Diego CA
1255 PM PDT Tue Jul 27 2021

Seasonal summer weather is expected this coming week. A
persistent marine layer will maintain a cloud cover near the coast
nights and mornings. Monsoon flow will ebb and flow into the
region, bringing small chances of afternoon thunderstorms mainly
to the mountains today and Wednesday, and to mountains and
deserts Friday and Saturday. It will be warmer through Thursday,
then not as warm this weekend.



Coastal low clouds were slow to clear from the beaches but they`ll
get sunshine this afternoon. Cumulus clouds have been forming
right over the highest mountain ridges, but have struggled to grow
into showers or thunderstorms...yet. There is a small chance one
or two could pop later this afternoon, most likely in the Big Bear
area. With today`s chance of thunderstorms being so marginal and
Wednesday looking even less favorable, there is too small of a
chance to keep them in the forecast. Thursday looks similar.
Cumulus clouds will develop over the mountains each afternoon.
High pressure aloft over the interior West will expand slightly
into California through Thursday. This should suppress the marine
layer a little, for less extensive coastal clouds in time and
space. It will also boost temperatures a few degrees, probably
reaching a little above normal by Thursday. That would mean parts
of the Coachella Valley exceeding 110 degrees. The monsoon
moisture flows back into the region Friday and Saturday for
greater chances of thunderstorms those days. It still looks like
the chance is mainly during afternoons for mountains and deserts.
The added humidity and cloud cover should decrease max
temperatures inland, but increase the min temps. A trough of low
pressure off the coast will gently nudge aside the monsoon
moisture on Sunday, ushering in drier air and taking out the
chance of thunderstorms. Ensemble guidance is still split on
whether the dry-trough scenario maintains the dry forecast next
week or if the ridge-wetter scenario would prevail. Most ensemble
members are going with the drier idea and so for now, next week
looks dry with seasonal temperatures.


272000Z...Coast/Valleys...Areas of BKN-OVC stratus will continue
along the immediate coast of San Diego County this afternoon with
bases around 1500 ft MSL. Stratus will spread inland again this
evening but be less extensive tonight than Mon night, with onset at
coastal airports between 02Z and 05Z Wed in San Diego County and 05Z
and 09Z Wed in Orange County. Bases will be 800-1100 ft MSL with
tops to 1500 ft MSL. Local vis will be 1-3 miles in BR mainly in the
coastal valleys 08Z-16Z Wed. Clearing will be faster Wed morning,
mostly 16Z-18Z.

Mountains/Deserts...There is a slight chance of ISOLD TSRA with CB
bases 9000 ft MSL and tops to 35000 ft MSL 20Z Tue-01Z Wed, mainly
over the San Bernardino Mountains. Except near TSRA, visibility will
be unrestricted, with mostly clear skies tonight through Wed.


No hazardous marine weather is expected through Sunday.


Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.






NWS SGX Office Area Forecast Discussion