San Diego Forecast Discussion

000
FXUS66 KSGX 291238
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
538 AM PDT Fri Mar 29 2024

.SYNOPSIS...
A strong Pacific storm will move slowly across the area this
weekend into Monday. It will be much cooler. Widespread moderate
to locally heavy precipitation on Saturday will become more
showery for Saturday night into Monday with a slight chance of
thunderstorms for Saturday into Sunday. Warmer and drier for
Tuesday and Wednesday with high temperatures around 5 degrees
above average on Wednesday. Then cooling for the end of next week
with a chance of precipitation.

&&

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

.SHORT TERM (Today through Sunday)...
A low pressure system centered off the northern California coast
early this morning will move slowly southward and be centered just
west of Point Conception for late Saturday afternoon, moving
inland across northern Baja and far southern California late
Sunday.

High temperatures today will be slightly cooler than Thursday near
the coast to around 10 degrees cooler for the mountains and high
desert. High temperatures for Saturday will be another 10 to 15
degrees cooler inland with Sunday only slightly less cool.

There will be gusty southwest to west winds for the mountains
and deserts today, strongest during the afternoon into the evening
with the stronger gusts along the desert slopes of the mountains
to 45 to 55 mph.

Lighter precipitation may develop this evening, but more
widespread and heavier precipitation is expected to be spreading
into areas east and south of Los Angeles County by Saturday
morning, spreading southward and eastward on Saturday morning.
There will be a period of strong gusty south winds ahead of the
cold front on Saturday morning with the stronger gusts near the
coast to around 40 mph.

The heaviest precipitation from before dawn through noon on
Saturday is expected along the south-facing slopes of the San
Bernardino County mountains with hourly rainfall up to one-half
to one inch per hour and snowfall of 1 to 2 inches per hour and
locally 3 inches per hour on the higher peaks.

Behind the front, showers will continue at times for Saturday
night and Sunday with more widespread showers and a chance of
thunderstorms for late Saturday night into Sunday.

&&

.LONG TERM (Monday through Thursday)...
Showers will linger near the mountains on Monday and are expected
to end by Monday evening. Tuesday and Wednesday will be drier and
warmer with Wednesday high temperatures around 5 degrees above
average. Then cooler for Thursday and Friday with a chance for
precipitation with another low pressure system centered in the
somewhere in the vicinity of the California coast.

&&

.AVIATION...
290935Z...Coast/Valleys...SCT-BKN clouds will continue through 18Z,
with some TAF sites likely SCT TEMPO BKN. Bases will rise from 1500-
2000 ft MSL to 2000-3500 ft MSL by 18Z, with tops to 5000 ft MSL.
Local vis 2-5 miles in BR in the valleys through 18Z. Otherwise, FEW-
SCT clouds above 20000 ft MSL through Fri evening, with clouds
developing in the 3500-7000 ft MSL layer Fri evening.

Mountains/Deserts...Local terrain obscurations in clouds will
occur below 5000 ft MSL on the coastal slopes through 18Z Fri. Areas
of west winds 20-30 kt with local gusts 35-45 knots will occur
mainly from the mountain crests east/north through the desert slopes
and into adjacent deserts through Fri evening, along with moderate
up/downdrafts and local LLWS. Otherwise, FEW-SCT high clouds above
20000 ft MSL and unrestricted VIS will continue through Fri evening.

&&

.MARINE...
No hazardous marine conditions are expected through Friday. A Small
Craft Advisory has been issued for southerly winds 20-25 knots with
gusts to 30 knots and choppy seas Friday night into Saturday
afternoon. The winds will shift from south to west as a front moves
through the coastal waters Saturday morning, with weaker winds and
less chop thereafter. There will be a slight chance of thunderstorms
Saturday night through Sunday.

&&

.BEACHES...
West southwest swells of 5-7 ft at 9-13 seconds could bring surf of
7-9 feet at times Saturday evening into Sunday afternoon. This will
make for dangerous swimming conditions. The highest surf will be on
exposed west-facing beaches in San Diego County. There will be a
slight chance of thunderstorms Saturday night through Sunday.

&&

.HYDROLOGY...
Widespread moderate to locally heavy precipitation will occur
this weekend. Lighter rain and mountain snow may begin as early as
this evening, increasing in coverage and intensity late tonight,
with the heaviest and most widespread activity occurring through
the day on Saturday, and again early Sunday morning through the
afternoon.

Through Monday, rainfall is expected to range from around 1.5 to 2
inches for the coasts and valleys to 2 to 3 inches in the
mountains, locally to around 5 inches on the south slopes of the
San Bernardino County mountains. For the deserts, one-half to one
inch is expected for the Apple and Lucerne Valleys, and one-
quarter to one-half inch for the lower deserts.

The snow level will rise to 5500 to 6000 feet for early Saturday
morning, fall to around 4500 to 5000 feet for Saturday night,
then fluctuate around 5000 to 5500 feet on Sunday. For the
San Bernardino County mountains, there could be snowfall of 1 to
3 inches from 4500 to 5000 feet, 3 to 6 inches from 5000 to 5500
feet, 6 to 12 inches from 5500 to 6000 feet, 12 to 18 inches from
6000 to 6500 feet, 18 to 24 inches from 6500 to 7000 feet, with
as much as 3 to 4 feet on the higher peaks above 8500 feet. The
most widespread and heaviest snowfall is expected on Saturday.

For the Riverside County mountains, snowfall of 1 to 3 inches is
expected from 5000 to 5500 feet, 3 to 6 inches from 5500 to 6000
feet, 6 to 12 inches from 5500 to 6000 feet, 12 to 18 inches from
6000 to 6500 feet, and up to 2 feet on the highest peaks above
8000 feet.

For the San Diego County mountains, snowfall of 1 to 3 inches is
expected from 5000 to 5500 feet and 3 to 6 inches above 5500 feet.
The greater potential for heavier snowfall in the San Diego
County mountains is on Saturday night and Sunday.

The current forecast for the San Diego River at Fashion Valley has
the river rising on Saturday, but remaining just below the low-
water crossings. With additional rainfall on Sunday, the river
could rise sufficiently to flood the low-water crossings late
Sunday into Sunday night.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Flood Watch from late tonight through Sunday afternoon for
     Orange County Coastal Areas-Orange County Inland Areas-
     Riverside County Mountains-San Bernardino County Mountains-
     San Bernardino and Riverside County Valleys-The Inland
     Empire-San Diego County Coastal Areas-San Diego County
     Mountains-San Diego County Valleys-Santa Ana Mountains and
     Foothills.

     Wind Advisory from 6 AM to noon PDT Saturday for San Diego
     County Coastal Areas-San Diego County Valleys.

     Winter Storm Watch from late tonight through Sunday afternoon
     for San Bernardino County Mountains.

     Winter Storm Watch from late tonight through Sunday afternoon
     for Riverside County Mountains.

     Winter Storm Watch from Saturday morning through Sunday
     afternoon for San Diego County Mountains.

     Wind Advisory from 2 PM this afternoon to 11 PM PDT this evening
     for Apple and Lucerne Valleys-Coachella Valley-San Diego
     County Deserts-San Gorgonio Pass Near Banning.

     Wind Advisory from 2 AM to 8 AM PDT Saturday for Orange County
     Coastal Areas-Orange County Inland Areas.

PZ...Small Craft Advisory from 11 PM this evening to 5 PM PDT
     Saturday 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.

&&

$$

PUBLIC/HYDROLOGY...17
AVIATION/MARINE/BEACHES...PG

NWS SGX Office Area Forecast Discussion