Alta Loma, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

695
FXUS66 KSGX 231736
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
936 AM PST Sat Nov 23 2024

.SYNOPSIS...
Below average temperatures are expected west of the mountains today,
with chances of showers this afternoon and overnight. Rain chances
will move from northwest to southeast, starting in Orange County and
southwestern San Bernardino County this afternoon and ending in San
Diego county by Sunday morning. The rest of Sunday and most of
Monday is expected to remain dry, with additional chances of
precipitation Tuesday and Wednesday. Periods of gusty westerly winds
for the mountains and deserts are expected tonight into Sunday and
again Tuesday into Wednesday. A gradual warming with dry conditions
for Thursday into next weekend is likely.

&&

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

Visible satellite at 9 AM was showing areas of high and low clouds
across the area. Cloud coverage is expected to increase into this
afternoon as an atmospheric river moves southeast across California.
Temperatures today are expected to be similar to yesterday for the
coast and deserts with 5 to 10 degrees of cooling for the valleys
and mountains. Chances of showers will begin to increase this
afternoon for Orange county and southwestern San Bernardino county.
Rainfall chances will move to the southeast into San Diego county
overnight and showers are expected to taper off by Sunday morning.
As far as forecast rainfall totals go, most low elevation areas will
see a tenth of an inch or less, with Orange and San Bernardino
counties the most likely place to see totals closer to a tenth of an
inch. Orographic effects are expected to bring higher rainfall
totals to the coastal slopes of the mountains, particularly the San
Bernardino Mountains. There is a 20 percent chance the coastal
slopes of the San Bernardino mountains could accumulate 0.50" or
more of rain, with a 70 percent chance of accumulating 0.25" or
more. Chances of 0.25" or more of rain is closer to 5 to 10 percent
for the Riverside and San Diego mountains.

Gusty west winds are expected over the mountains and into the
deserts. Winds will begin to increase this morning, peaking late
tonight into early Sunday. Favored mountain passes and canyons could
get wind gusts of 35 to 40 mph. Winds will weaken by Sunday
afternoon. Snow levels will remain near or above 7000 ft through
Sunday. Only minor snow accumulations are expected.

Another moisture surge is expected for early to mid next week. Cool
and cloudy conditions are expected, with periods of rain most likely
Tuesday and Wednesday. Most ensemble members for both the ECMWF and
GEFS are showing mostly light precipitation in and west of the
mountains for Tuesday and Wednesday. This set of unsettled weather
looks like it will be more of an impact to areas north of Southern
California. In addition to periods of rain, gusty winds are again
expected for the mountains and deserts. Snow levels are expected to
remain 7000 ft and above. Temperatures are expected to remain below
average for areas west of the mountains through the middle of the
week.

Most model solutions show weak ridging building over Southern
California for Thursday through next Saturday. This increases the
likelihood of dry and warmer weather for the end of the week. There
is a small percentage of ensemble members for both global models
showing precipitation, but there is more support for a drier and
warmer solution at this time.

&&

.AVIATION...
231645Z...Coast/Valleys...Clearing along the coasts is already
beginning to occur with a few sites still seeing SCT-BKN low clouds
with bases >1000ft MSL with tops to 1800ft MSL, completely clearing
by 19z. Increasing mid-high clouds today and tomorrow with bases
generally around 7,000-10,000ft MSL, becoming BKN-OVC by tonight.
Low clouds return by 22Z Sat-02Z Sun in all coastal/valley areas
with bases 1200-2000 ft MSL and tops 4000-7000 ft MSL and with areas
of terrain obscurations in clouds/-SHRA. Local VIS 3-5 miles will
occur in -SHRA mainly 00Z-12Z Sun. Most areas will clear 18-20Z
Sunday, but mid to high clouds will prevail through all of Sunday.

Mountains...Areas of terrain obscurations will occur 22Z Sat-08Z Sun
in the San Bernardino County/Riverside County mountains and 01Z-12Z
Sun in the San Diego County mountains due to clouds/FG/-SHRA,
especially on the coastal slopes, with cloud tops mostly to around
10,000ft MSL. Mid level cloud cover with SCT-OVC will prevail for
most of Sunday.

Deserts...Mostly clear skies with unrestricted VIS will prevail
through this afternoon. Increasing cloud cover tonight ahead of an
atmospheric river will bring FEW-SCT high clouds with bases 10,000-
12,000ft MSL, becoming SCT-BKN by Sunday morning with similar bases.

&&

.MARINE...
No hazardous marine weather is expected through Wednesday.

&&

.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...CO
AVIATION/MARINE...Zuber