San Diego Forecast Discussion

FXUS66 KSGX 011018

Area Forecast Discussion
National Weather Service San Diego CA
318 AM PDT Sun Oct 1 2023

A low pressure system will bring another unseasonably cool day
with isolated to scattered showers ending late in the day. Dry
and warmer weather will begin Monday as the low pressure weakens.
High pressure and increased offshore flow will boost the warming
trend for above normal temperatures Wednesday through Saturday.



Isolated showers in coastal and valley areas, and scattered
showers in the hills and mountains, are continuing this morning.
Isolated wind gusts over 35 mph through the mountain passes
indicate that winds have decreased overall and will continue to do
so this morning. The unstable air mass today underneath the core
of the upper level trough will continue to support shallow
convection for these isolated to scattered showers anywhere from
the coast to the mountains for much of the day, ending this
evening. There doesn`t seem to be sufficient instability for
thunderstorms, but a few showers could be briefly heavy.
Additional rainfall in the mountains could exceed 0.25 inch, but
most areas will receive an additional 0.01 to 0.15 inch. Our cool
and mostly cloudy environment today will produce high
temperatures inland 15-25 degrees below average, so look for more
low max temp records to fall, like they did yesterday. Random and
intermittent clearing of clouds will gradually take place tonight
into Monday as the upper low weakens and lifts out. The marine
layer will try to recover, but coastal clouds appear patchy at
most Tuesday, and non-existent thereafter. High pressure begins to
build, but a weak remnant upper low seems to hang out over
Arizona Wednesday and Thursday. With colder air over the
intermountain west, an offshore pressure gradient sets up. The
northerly flow aloft will assist the offshore flow. It starts
weak Tuesday, but strengthens for Wednesday through Thursday. The
air mass warms and the offshore flow will greatly boost
temperatures west of the mountains. After max temps 15-25 degrees
below normal today, we`ll approach normal Tuesday, then zoom well
above normal for the rest of the week. We`re looking at widespread
90s on Thursday in the valleys and inland coastal areas, about
4-12 degrees above normal. Offshore Santa Ana wind gusts of 25-35
mph look probable in the foothills, right now looking most
favorable during the nights and mornings Wednesday and Thursday.
Right now the stronger winds don`t appear to reach too far into
the populated lowlands if at all. There is some weakening of the
high pressure and offshore flow toward the weekend that should
help ease temperatures back to normal. The atmosphere seems to
have checked the calendar and noticed that October is here, and
better shape up and start acting like it. The season appears to be
turning the page.


010925Z...Coast/Valleys...Sct -SHRA through 21Z. BKN-OVC clouds
through 21Z gradually become SCT/BKN through 02Z Mon, then becoming
SKC/SCT thereafter. Bases will be variable between 2000-5000 ft MSL,
layered to 7000 ft MSL today.

Mountains/Deserts...Areas of mountain obscuration in clouds and
-SHRA through 23Z. Decreasing cloud cover tonight. Areas of W-SW
winds gusting 25-40 knots on the mountain crests and the desert
slopes east of San Gorgonio Pass through 20Z.


No hazardous marine conditions through Thursday.


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






NWS SGX Office Area Forecast Discussion