Green Valley Lake, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

665
FXUS66 KSGX 282128
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
128 PM PST Sat Dec 28 2024

.SYNOPSIS...
A building high pressure ridge will bring a shallow marine layer,
with low clouds and fog in the coastal areas and western portions
of the inland valleys each night and morning through Monday. Dense
fog could impact some areas. Offshore flow will develop Tuesday
through Thursday, bringing gradual warming and much drier
conditions, with periods of Santa Ana winds. Cooler next Friday
and Saturday as a low pressure trough approaches from the west.

&&

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

This afternoon...The marine layer is a little shallower with low
clouds and fog lingering at some beaches. Otherwise, high clouds
continue to stream overhead from northwest to southeast in the
flow across the building ridge aloft. Inland away from the marine
layer influence, temperatures are anywhere from 5 to 20 degrees
higher than at this time yesterday. Temperatures at low elevations
west of the mtns are mostly in the 60s.

From previous discussion...
As the upper level high pressure ridge continues to build, the
marine layer will become shallower with increased chances for
dense fog in the coastal areas late tonight into Sunday morning as
the inland extent of the marine layer is reduced. A weak short
wave trough moves inland to the north late Sunday, weakening the
ridge and strengthening the onshore flow. West winds gusting to 30
mph in the mtns and deserts will likely develop Sunday afternoon
and evening. The deserts will be a little warmer on Sunday, with
high temperatures as much as 17 degrees above normal in the high
deserts. The marine layer remains shallow into Monday morning,
likely resulting in another night of dense fog for the coastal
areas.

A third shortwave moves inland to our north Monday night/Tuesday
morning. A surface high follows this trough and settles into the
Great Basin setting up offshore pressure gradients which will
produce periods of Santa Ana winds with dry conditions for
Tuesday through Thursday. There is still significant uncertainty
with respect to the timing and strength of the winds due to the
spread among model solutions, however we can say with some
confidence that conditions will be dry, and that Wed and Thu will
be significantly warmer west of the mtns, with daytime high temps
reaching the low 80s in some valley locations.

Onshore flow will return on Friday ahead of a low pressure trough
approaching from the northwest. Friday will remain unseasonably
warm before cooling begins to spread inland on Saturday with the
return of the marine layer. The consensus solution among models
is for no precipitation with this low pressure trough.


&&

.AVIATION...
282113Z...Coast/Valleys...Areas of low clouds along the coasts and
up to 5 miles inland. Bases generally 900-1200ft MSL. Most locations
will have VIS of 5+ miles though 1-3 miles is possible at times for
coastal mesas.

Low clouds look to redevelop and move back ashore around 01-03z
Saturday evening, but bases should be a few hundred feet lower than
this morning, around 400-700ft MSL. More VIS restrictions
anticipated, including the coasts which could fall below 2 miles at
times.

Mountains/Deserts...SCT-BKN high cirrus clouds with unrestricted VIS
will prevail through early Sunday morning.

&&

.MARINE...
West-northwesterly swells will continue through Sunday. Seas will be
5-8 feet in the outer coastal waters (30-60 NM from the coast) and 3-
5 feet in the inner waters (within 30 NM). Otherwise, no marine
weather hazards are expected through Wednesday.

&&

.BEACHES...
The long period (15 to 17 seconds) northwesterly (280-290 degree)
swell of 3-5 feet will continue through Sunday, decreasing Monday.
Elevated surf of 4-7 feet will continue through Monday at San Diego
County beaches with local sets to 8 feet on west-northwest facing
beaches. Minor coastal flooding is possible in vulnerable areas
during morning high tides as tides will increase this weekend
(peaking on 12/31), coinciding with the elevated surf. See the Beach
Hazards Statement for more information.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Sunday afternoon for San Diego
     County Coastal Areas.

PZ...None.

&&

$$

PUBLIC...PG
AVIATION/MARINE/BEACHES...Small