Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 292018

Area Forecast Discussion
National Weather Service San Diego CA
Issued by National Weather Service Los Angeles/Oxnard CA
117 PM PDT Thu Sep 29 2022

Onshore flow will strengthen into the weekend, helping to build the
marine layer inland, and bringing drier, more stable conditions to
the mountains and deserts. Low clouds and fog will return to the
coastal areas each night, and then burn away during the late morning
to midday. Inland areas will be cooler, as the marine air works
farther inland. There is a small chance of thunder returning to the
mountains on Sunday, but a gradual rebuilding of the ridge over the
Southwest next week, will likely bring dry and warmer days to round
out the first full week of October.



Marine stratus was slow to burn away from coastal areas this
morning, and remained sticky along the coast into the afternoon.
Meanwhile farther inland, cumulus clouds were boiling over the
mountains, and by midday, a few had become showers, and an isolated
thunderstorm or two. Wind reports were mostly light, but turning
from E, to SW-W far inland, where the sea breeze had penetrated.
Strongest gusts at midday were south around 35 MPH through the Cajon
Pass. Isolated stronger gusts are possible near the stronger
thunderstorms through late afternoon, along with brief, heavy
downpours and frequent, dangerous lightning.

Low pressure is moving inland over the PacNW today, and will
eventually become stationary over the northern Rockies this weekend.
This feature is marginally helping to increase the onshore flow,
which is expected to prevail into early next week, aided by the
thermal gradient to the deserts. As this flow continues to develop
farther inland, residual, monsoonal moisture will be chocked off,
which should end the thunderstorm threat in the mts/deserts through
about Saturday, while increasing the coverage of stratus development
each night inland. The marine layer depth should reach it`s maximum
on Sunday morning, then slowly subside. By Sunday, there could be
another weak monsoonal push into our mountains too, as a weak
disturbance passes to our south. A slight chance of thunder returns
to the forecast then.

For next week, the low over the northern rockies will be coaxed
northeastward by a building ridge over the West, and the westerlies
farther to the north. This will not have any major impacts on our
weather, and should maintain an onshore flow and shallow marine
layer over coastal areas. There is some disparity in the ensemble
solutions though, but the majority show some warming for SoCal into
mid next week under this ridge.


291920Z...Coast/Valleys...Mostly clear skies continue away from the
immediate coast, where low clouds will likely continue to linger
through much of this afternoon. Expect low clouds to move back
inland between 01-04z Fri near SAN/CRQ and between 03-06z for areas
near SNA. Slightly higher bases expected this evening and Friday
morning, generally 500-100 FT MSL. Some BR/FG reducing VIS to 0-3SM
possible in coastal foothills and coastal mesas.

Mountains/Deserts...Mostly clear skies and unrestricted VIS through
this evening. Some CU/CB based near 10,000 FT MSL and scattered TSRA
possible in San Diego/Riverside Mtns this afternoon. Gusty and
erratic winds and MOD-STG up/downdrafts expected near any TSRA.


No hazardous marine weather is expected through Monday.


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





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