Area Forecast Discussion
Issued by NWS San Diego, CA
FXUS66 KSGX 292022
Area Forecast Discussion
National Weather Service San Diego CA
122 PM PDT Sat Apr 29 2017
A limited sea breeze this afternoon will strengthen over the next
few days, bringing marine air with associated low clouds and fog
back to coastal areas late Sunday night into Monday morning. In the
meantime, it will remain fair, with warm days inland next week as
high pressure builds over the West. Cooler again next weekend as low
pressure develops near the West Coast and onshore flow strengthens.
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
Skies were completely clear this afternoon across the entire CWA and
adjacent coastal waters. Temperatures were running some 5 to 12
degrees F above values observed yesterday at midday along the Coast.
Surface pressure gradients remained weak to moderate offshore from
the deserts at Noon. The Wind Advisories/Warnings have expired, but
we still have some isolated peak gusts in wind-prone areas in the 45-
50 mph range.
The pattern...A deep low pressure trough over the central U.S., and
strong high pressure over the EastPac will maintain a NW flow aloft
over SoCal through the first half of next week. For mid next week,
the ridge off the coast drifts inland across CA, then farther east
as a sharp long-wave trough deepens along the West Coast over the
The weather...After a very warm day today, cooling will begin over
coastal areas Sunday as onshore flow increases. Inland areas will
remain quite warm under fair skies. Daytime temperatures will be
near, to slightly above average along the Coast, and 5 to 10 degrees
F above average inland through Thu. Low clouds/fog will likely
become more prevalent under a strong marine inversion for the coming
week, perhaps not totally clearing the beaches some days. Once the
ridge drifts off to the east, onshore flow will increase further
Fri, into the weekend, deepening the marine layer for further
For the extended period...After next Saturday, the global models are
coalescing around a large omega blocking pattern across the western
hemisphere. For now, the western cut-off portion of this block is
favored to develop just off the SoCal Coast. If this position of the
cut-off were to verify, it would be much cooler, with even some
showers possible. But given the fickleness of cut-offs, and how far
this is into the future, it would be prudent to lean toward
climatology at this point.
292030Z...Northeast winds gusting 20-35 kt will continue this
afternoon along coastal mountain slopes and through mountain passes
and into adjacent valleys. MDT up/downdrafts and LLWS are likely
through this afternoon just west of the mountains, continuing to
impact KONT, KSBD and KSNA. Winds will gradually weaken through the
afternoon and evening. Otherwise, clear with unrestricted vis
Northwest winds gusting near 20 kt are likely over the coastal
waters this afternoon through early tonight. Otherwise, no hazardous
marine conditions are expected through Wednesday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.