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000
FXUS66 KSGX 060346
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
845 PM PDT Wed May 5 2021

.SYNOPSIS...
A trough moving inland over California will bring stronger onshore
flow and cooler weather into the weekend. Gusty westerly winds will
develop on Friday over the mountains and into the deserts, pulling
in a deeper marine layer with more extensive low clouds and patchy
fog well inland each night and morning. This Springtime pattern will
persist much of next week with temperatures close to average.

&&

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

Satellite imagery showed extensive low clouds over the CA Bight and
along the immediate coast at 8 PM PDT. The 00Z Miramar sounding had
a 6C inversion based near 1700 FT MSL. Cloud bases were initially
near that 1700 FT level late this afternoon at coastal airports,
likely propped up by a moderate coastal eddy circulation. That eddy
has weakened, which may allow the clouds to settle a bit, as they
get drawn inland overnight on weak onshore sfc pressure gradients/
trends. Expect some fog, locally dense as well, especially along the
higher coastal terrain and well inland. No forecast changes.

From previous discussion...

A low pressure system will move inland over the Pacific Northwest
Thursday through the weekend. This will increase onshore flow and
spread cooler marine air inland. The marine layer will deepen and
spread into portions of the valleys each night and morning. West
winds will become gusty on Friday over the mountains and deserts,
with peak gusts to 40 mph. Higher gusts to 50 mph are possible
through the San Gorgonio Pass. Periods of gusty west winds will
continue Saturday but don`t look to be as strong as Friday.
Another round of gusty west winds are possible on Sunday.

There continues to be some spread in the ensembles on how long
this low pressure system will stick around over the West. For now,
it appears the low pressure system will continue to bring us
cooler weather through at least Sunday, possibly into Monday.
Ensembles are indicating high pressure building back in sometime
Tuesday or Wednesday, which would bring us slightly warmer
temperatures and a shallower marine layer.

&&

.AVIATION...
060330Z...Coast/Valleys...Stratus along the coast will gradually
spread up to 25-30 miles inland overnight. Bases will be 900-1500 ft
MSL with tops to 1700 ft MSL. Areas of vis 2-4 miles will occur over
higher coastal terrain and in the valleys with local vis below 1
mile in the valleys 09Z-16Z Thu, including near KRNM, KF70, KAJO.
Most areas will clear 15Z-18Z Thu, except locally along the beaches
where stratus could linger Thu afternoon. Stratus will expand again
Thu evening with slightly higher bases.

Mountains/Deserts...Mostly clear with unrestricted vis through Thu
evening.

&&

.MARINE...
No hazardous marine conditions are expected through Monday.



&&

.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...10/Connolly
AVIATION/MARINE...Maxwell