Alta Loma, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

785
FXUS66 KSGX 022045
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
145 PM PDT Wed Apr 2 2025

.SYNOPSIS...
A low pressure system over the western states will continue the cool
weather with periods of showers through Thursday. Shower activity
will taper off this afternoon then increase again tonight through
Thursday evening with the greatest coverage and amounts of
precipitation over the mountains. Dry and warmer for the weekend
into next week, with high temperatures rising to around average
over the weekend and 10 to 15 degrees above average for inland
areas for the middle of next week.

&&

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

Isolated light showers continue this afternoon, mainly in San
Diego County. High-resolution models continue to show increasing
shower activity through tonight and Thursday. Onshore winds
continue to weaken with the windiest locations reporting gusts of
around 40 mph in the last hour.

From previous discussion...
An extensive area of low pressure will continue to dominate the
synoptic pattern into the weekend. The mean trough will become
narrower through Friday as the pattern becomes more amplified. Cold
air filtering in aloft from the north and northwest will maintain
unstable conditions and promote showers through Thursday. A
disturbance moving southeast in the cold air on the backside of
the mean upper level trough will bring a slight chance of tstms on
Thursday. Additional rainfall and liquid-equivalent above the
snow level will range from less than one-tenth inch near the
coast to one-quarter inch inland and up to three-quarters inch in
the mountains, with locally greater amounts. The snow level will
rise to 4500-5000 feet this afternoon, lower to 4000-4500 feet
late tonight, then rise to 5000-5500 feet Thursday afternoon into
Thursday evening. Snowfall of a few inches is possible above 5000
feet with locally 4 to 7 inches above 7500 feet. Daytime high
temperatures will remain below seasonal averages through Friday
although a warming trend begins on Friday as conditions begin to
dry out.

By Sunday, daytime high temperatures rise to above seasonal
averages as the upper level low pressure trough moves east and
a ridge of high pressure moves over the region from the west. A
weak trough of low pressure moves inland to the north but will
have minimal impacts for SoCal. A more robust high pressure ridge
begins to build over the west on Tuesday and by Wednesday,
temperatures will rise to as much as 18 degrees above seasonal
averages in the inland valleys.

&&

.AVIATION...
022015Z...Coast/Valleys/Coastal Mountain Slopes...SCT to
occasionally BKN clouds based between 2500-4500 feet MSL with tops
reaching 7000 feet will continue today, with predominantly FEW-SCT
conditions vcnty KSNA. Cigs below 3000 feet MSL and isolated
-SHRA most likely far inland against the coastal slopes and in San
Diego County this afternoon. West-northwest winds gusting 25-30
kts today near the coast through this evening. Clouds will lower
and become more widespread, more widespread -SHRA return, and
winds will gradually diminish after 02Z today. Cloud bases will
locally lower to 2000-3500 feet MSL, lowest in -SHRA, after 02Z
into Thursday, most likely near mountains and in San Diego County.
Bases rise again to mostly above 3000 ft MSL after 13Z Thu.
Partial scattering will occur late Thursday morning into the
afternoon, but clouds and -SHRA will linger along the coastal
slopes and in San Diego Co. -SHRA tapering off by 05Z Thu.

Desert Mountain Slopes/Deserts...Mostly clear skies today and
tonight. Westerly winds with gusts 30-40 kts over the ridges,
through mountain passes, and locally into adjacent deserts. Winds
weaken to 25-35 kts and become more isolated in these areas this
evening, then gradually calm overnight. Areas of moderate
up/downdrafts in lee of mountains this afternoon and early evening.

&&

.MARINE...
Strong northwest winds and hazardous, steep seas will continue
today. Winds and seas gradually diminish from the inner coastal to
the outer coastal waters this evening through early Thursday. See
the Small Craft Advisory for details. Winds and seas will continue
to diminish Thursday and beyond, and no additional hazardous marine
conditions are expected Thursday through Sunday.

&&

.BEACHES...
Surf of 4 to 7 feet with local sets to 9 feet in San Diego County
will generate dangerous rip currents, hazardous swimming conditions,
and localized beach erosion today. Surf will gradually subside
Thursday. The High Surf Advisory is in effect through this evening
and contains more details.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory until 11 PM PDT this evening for San Diego
     County Coastal Areas.

PZ...Small Craft Advisory until 5 PM PDT this afternoon for Coastal
     Waters from San Mateo Point to the Mexican Border and out
     to 10 nm.

     Small Craft Advisory until 7 AM PDT Thursday for Waters from San
     Mateo Point to the Mexican Border Extending 10 to 60 nm out
     including San Clemente Island.


&&

$$

PUBLIC...PG
AVIATION/MARINE/BEACHES...CSP