Weather Service Report


409 
FXUS66 KSGX 220915
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
215 AM PDT Mon Oct 22 2018

.SYNOPSIS...
A trough of low pressure moving slowly inland across Southern 
California will bring cooler weather through Tuesday. A deeper 
marine layer will bring more night and morning low clouds to the 
coast and western valleys. The weather will turn much warmer 
Wednesday through Friday as high pressure over the eastern 
Pacific builds over central California. 

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

Low clouds have organized and uniform coverage is marching inland
this morning. It looks like clouds and fog might barely sneak 
into the Inland Empire through its western and southern portals 
before sunrise. Patchy fog with low visibility could occur 
anywhere between 1,200 to 1,800 feet elevation. Meanwhile, there 
are thunderstorms(!) in the desert of San Bernardino County, yes 
even this time of the morning. A weak upper low moving through 
Southern California can explain the storms and also the marine 
layer development. We don't expect the moisture or instability to 
be sufficient for storms in our region today, but you'll see some 
cumulus clouds over the interior, especially in the mountains. 
And that looks to be the case through Tuesday and Wednesday. The 
marine layer and coastal cloud coverage will be similar through 
Tuesday. There will be some high clouds from time to time as well.
As the low moves on, the higher pressure will tamp down the 
marine layer a step for Wednesday and Thursday for less cloud 
coverage in time and space. There's also a touch of offshore flow 
each morning; after all we are in October. A high pressure ridge 
over the eastern Pacific Ocean noses boldly into California as we
head into the weekend. A little more offshore flow will develop 
to bring areas of offshore breezes. The combination of ridging 
aloft and the offshore flow at the surface will boost temperatures
quite a bit for Thursday through Saturday. Right now it appears 
the warmth peaks Friday, particularly for the coastal basin. As 
the offshore flow weakens over the weekend, the warmth will 
migrate into mountains and deserts. High temps on Friday will
feature some 90s. The upper ridge weakens slightly next week with
some form of western trough coupled with a baggy weak trough to 
our south. This would probably bring us more low and high clouds 
and slightly cooler weather.

&&

.AVIATION... 
220850Z...Coast/Valleys...Stratus with bases 1100-1500 ft MSL 
continuing along the coast and local 15-20 mi inland this morning. 
Local vis 3-5 SM in BR/HZ along inland extent of low clouds. 
Clearing to the coast will occur 16-19Z, though beaches may remain 
locally BKN through the afternoon. Stratus will spread back into the 
coastal areas around 23/02Z and 15-20 mi inland overnight. Bases 
will remain near 1000-1500 ft MSL. 

Mountains/Deserts...FEW-SCT mid and high clouds and unrestricted vis 
through Tuesday morning.

&&

.MARINE...
No hazardous marine weather is expected through Friday.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC...MM
AVIATION/MARINE...SS

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Western Regional Climate Center, wrcc@dri.edu