Area Forecast Discussion
Issued by NWS San Diego, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
FXUS66 KSGX 172043

Area Forecast Discussion
National Weather Service San Diego CA
143 PM PDT Sat Mar 17 2018

A few light showers this afternoon, mainly in San Diego County. Another
round of showers is expected late this afternoon and evening,
ending late tonight. Snow levels will be 4000 to 4500 feet. Cool
today with southwest to west winds gusting to 45 mph on the
desert slopes of the mountains. Dry and warmer Sunday through
Tuesday. A low pressure system over the eastern Pacific could
bring rain to areas bordering Los Angeles County on Wednesday with
greater chances for rainfall across much of southwest California
for Thursday into early Friday.



The showers have mostly dissipated but a few remain this
afternoon, mainly in San Diego County. So far, the location with
the greatest amount of rainfall is located on Palomar mountain at
1.07 inches. Several other locations have reported amounts of 0.75
inch or greater. The snow level is between 4500 and 5000 ft and
amounts of up to 7 inches have been reported in the San Bernardino
mountains. A second shortwave approaching from the northwest will
bring another round of organized precip to the region late this
afternoon/evening, before moving away to the east late tonight.
Total rainfall will range from two tenths to one inch near the
coast and one half to one and one half inch in the mountains with
locally greater amounts.

In the mountains, snow levels 4500 to 5000 feet this afternoon
will lower to around 4000 feet late tonight. Total snow
accumulations of a trace to 1 inch are expected between 4000 and
5000 feet, 2 to 5 inches from 5000 to 6000 feet, and 5 to 7 inches
above 6000 feet with local accumulations to 10 inches on the
highest peaks of the mountains in San Bernardino and Riverside

Gusty southwest to west winds will continue into tonight with,
gusts to 45 mph from the mountain ridge top onto the desert slopes.
Strongest gusts to 55 mph are expected for this evening along the
east slopes of the mountains from the San Bernardino Mountains

For Sunday through Tuesday...high pressure aloft will build over
California with a low pressure system farther off the coast,
centered along 140W. This will bring dry weather with a warming

For Wednesday through Friday...Deterministic models still show
some differences in solutions and the forecast favors the
solutions from the ECMWF and Canadian models. This would bring an
initial round of more significant precipitation for central and
northwestern portions of Southern California for Tuesday night
into Wednesday. Some of that precipitation might extend into areas
bordering Los Angeles County on Wednesday. As the upper trough
off the West Coast begins to move eastward...more significant
precipitation would spread across much of Southern California
Wednesday night and Thursday...decreasing early Friday.


1172015Z...Mountains westward...SCT-BKN cloud layers 3000-5000 ft MSL
with higher layers to near 10000 feet MSL through about 18/1000Z
Sunday morning, and isolated showers. Showers and BKN clouds mainly
near KSAN in the south, and about 5-10 SM east of the coastline
elsewhere through 18/0200Z this evening, becoming more widespread
overnight after about 18/0200Z.

At KSAN the risk of BKN-OVC low cloud bases below 2500 feet MSL is
low so confidence in the higher bases per the TAF is moderate-high.

Desert mountain slopes/deserts...west winds 20-30 kt with gusts to
45 kt through 17/2300Z-18/0600Z with strong UDDFS and wind shear.


West-northwest winds 15-25 kt developing this evening through Sunday
morning. A Small Craft Advisory is in effect from 7 PM this evening
through 4 AM Sunday.

Showers will continue at times today through Sunday morning.


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


CA...Winter Weather Advisory until 3 AM PDT Sunday for Riverside
     County Mountains-San Bernardino County Mountains-San Diego
     County Mountains.

PZ...Small Craft Advisory from 7 PM this evening to 4 AM PDT Sunday
     for Coastal Waters from San Mateo Point to the Mexican
     Border and out to 30 nm-Waters from San Mateo point to the
     Mexican Border Extending 30 to 60 nm out including San
     Clemente Island.



AVIATION/MARINE...Small is the U.S. government's official web portal to all federal, state and local government web resources and services.