San Diego Forecast Discussion

FXUS66 KSGX 090424

Area Forecast Discussion
National Weather Service San Diego CA
923 PM PDT Thu Jun 8 2023

Weather on Friday will be similar to today, ahead of an approaching
low pressure system for the weekend. The low will bring additional
cooling, a deeper marine layer and scattered showers Saturday night
and Sunday. Westerly winds will be gusty over the mountains and
deserts, where isolated thunderstorms will be possible Sunday
afternoon. Gradual warming sets in next week, but low pressure aloft
will keep night and morning clouds in the mix, and the days will be
cooler than average.



Skies cleared well west over the coastal waters today, but are
slowly filling back in this evening. The 00Z Miramar sounding had the
marine inversion base at 3K FT MSL. This means the marine layer is
still deep enough to develop well inland across the valleys by
morning. Moderate onshore sfc pressure gradients continue to the
deserts and are supporting some wind gusts of 40-50 MPH through and
below the San Gorgonio Pass. A minor change was made to the forecast
for tomorrow to allow partly cloudy skies over coastal areas.

Some minor updates have been added to the grids this evening for
less clouds tomorrow afternoon, and some patchy drizzle along the
coast on Saturday morning.

From previous discussion...

Today will likely be the warmest day of the week for many
locations west of the mountains before another low pressure system
arrives this weekend. The marine layer will deepen as the low
pressure system arrives, and may be deep enough to support areas
of drizzle Friday night into Saturday. Cooling also spreads inland
this weekend with many inland valley locations experiencing highs
nearly 15 to 20 degrees cooler than normal.

The weekend system will also bring chances for showers and
thunderstorms, mainly from the San Bernardino Mountains into the
High Deserts, for late Saturday into Sunday in addition to more
chances for drizzle at the coast as the marine layer rapidly
deepens. Ensemble PWAT guidance currently ranges from 0.75-1.00
inch near the coast to perhaps upwards of 0.50-0.60 inch in the
mountains by Sunday. Accordingly, there is still a fair amount of
spread in model QPF solutions for this weekend, with about one
half of EPS members showing 0.10” or less for Big Bear, and a
handful of members showing notably wetter solutions of 0.50” or
more. Greater confidence exists in the drizzle potential with
nearly all EPS members on board, all showing roughly 0.10” of
precipitation for Saturday and Sunday.

There will also be persistent rounds of increasing onshore winds,
especially over the mountains and deserts each afternoon and
evening today through the weekend. Saturday looks to have the
strongest wind activity as the 500mb low approaches, with gusts of
50-60 mph possible over ridgelines, through wind-prone canyons,
and below passes. Slightly weaker, but still elevated winds will
occur today and Friday afternoon as well as on Sunday.

The 500mb low and trough look to weaken for next week, leading to
a warming trend and a shallower marine layer each day. It will
remain deep enough to still support night and morning low clouds
all the way onto the coastal mountain slopes early next week, but
becoming more confined to the coasts and valleys by the middle
portions of next week. Temperatures will also steadily warm by
about 2 to 5 degrees each day next week.


090300Z...Coast/Valleys...SCT-BKN020-030 through 07Z...then becoming
OVC020-030 through 14Z Friday with tops 3500 ft. Valley clearing
Friday 17Z-20Z. Coastal clearing 20Z-24Z.

Mountains/Deserts...SCT250 tonight and Friday. WNW wind gusts 25-40
kt through 10z Fri.


No hazardous marine conditions are expected through Monday.


A fading south swell will generate 2-4 ft surf Friday with sets to 5
ft at the favored southwest-facing beach breaks. This downward trend
in surf and swell continues Saturday.


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






NWS SGX Office Area Forecast Discussion