Flash Flooding and Flooding in California, February 13 to 14, 2025

Area Forecast Discussion
National Weather Service San Diego CA
332 AM PST Thu Feb 13 2025

.SYNOPSIS...
Mostly lighter rainfall will continue across San Diego County
today. Precipitation will become more widespread for Orange and
southwestern San Bernardino Counties this morning with the
precipitation becoming heavier this afternoon and spreading
southeastward across the area this evening with the cold front.
Showers will continue at times on Friday, decreasing and ending
from the northwest Friday night. There will also be periods of
stronger and gusty southwest to west winds for the mountains and
for today into late Friday night with gusts to 45 to 55 mph and
isolated gusts for this evening to 65 to 75 mph on the desert
slopes of the mountains. Drier with warming for Saturday and
Sunday, then a little cooler for early next week.

&&

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

.SHORT TERM (Today through Saturday)...
A low pressure system with a feed of moisture from an atmospheric
river will move inland into California today and tonight, moving
east on Friday and Friday night.

For San Diego and western Riverside Counties, mostly lighter
rainfall will continue today with the greater totals on the
coastal mountain slopes. For Orange and southwestern San
Bernardino Counties, rainfall will become more widespread this
morning and heavier this afternoon. The cold front is expected to
move southeastward across the area this evening with heavier
precipitation and a slight chance of thunderstorms. Showers will
continue at times for late tonight through Friday, decreasing and
ending from the northwest Friday night. There is also a slight
chance of thunderstorms for this evening with the cold front.
Please refer to the hydrology section below for more details on
the precipitation and snow levels.

There will be periods of stronger and gusty southwest to west
winds for the mountains and for today into late Friday night with
gusts to 45 to 55 mph and isolated gusts for this evening to 65 to
75 mph on the desert slopes of the mountains. For the coast and
valleys, the strongest winds are expected for this evening with
gusts of 25 to 35 mph.

Saturday will drier and warmer, but with high temperatures still a
few to around 5 degrees below average with high temperatures for
the coast and valleys mostly in the 60s with lower 70s in the
lower deserts.

&&

.LONG TERM (Sunday through Wednesday)...
Warming will continue on Sunday with Sunday high temperatures a
few to around 5 degrees above average, in the lower to mid 60s
near the coast to the mid 60s to lower 70s in the valleys with the
lower deserts mostly in the mid 70s. Monday and Tuesday will be a
little cooler as a low pressure system moves inland to the
north, strengthening the onshore flow across southern California.
Then a little warmer for Wednesday and Thursday as high pressure
aloft moves inland along the West Coast.

&&

.AVIATION...
131100Z...Coast/Valleys/Foothills...More persistent light rain
showers have filled in across the coasts and valleys, with less
coverage in the south-central Inland Empire. These showers have
brought CIGs down to 400-600ft MSL with VIS generally ranging from
4SM down to 2SM in -RA BR. This rain/mist and associated CIGs and
VIS will likely continue through the morning and into the afternoon
with occasional breaks that may see brief periods of higher
CIGs/VIS. As an atmospheric river pushes into the region this
evening, periods of +RA are possible, especially for northern and
inland areas beginning as early as 00z, and slowly pushing
southeastward into southern San Diego County by 09z Friday morning.
VIS may fall as low as 1/2-1SM at times in areas of +RA. There is a
slight chance of embedded isolated thunderstorms within these rounds
of +RA as well. Scattered southerly gusts to 20-25kts around 15Z
will become more widespread after 00Z Friday, weakening
substantially by 12z.

Mountains/Deserts...Coastal slopes of the mountains obscured in FG
up to 7000ft MSL. SHRA is currently transitioning into more of a
steady RA around with pockets of +RA possible along the coastal
slopes after 18z. For the deserts, -SHRA may allow intermittent IFR
conditions, with -RA spreading in generally after 17z. Gusty winds
return for the High Desert and desert slopes after 15Z Thursday
becoming stronger and more widespread late Thursday. Widespread
gusts of 25-40kts by 00Z Friday with localized gusts to 60kts along
the desert slopes of the San Bernardino County Mountains. Moderate
to severe updrafts/downdrafts possible east of the mountains.

&&

.MARINE...
Periods of stronger winds and choppy seas through Friday. Southwest
winds of 10 to 20 knots with gusts to 25 knots expected Thursday and
Thursday evening across all of the coastal waters as well as seas of
5 to 8 feet...a Small Craft Advisory is in effect and contains more
information. Westerly winds increase again on Friday, with gusts 20-
25 kts and seas 7 to 11 feet possible in the outer waters,
diminishing Friday night.

Rounds of moderate to heavy rainfall expected Thursday evening into
early Friday morning. Embedded isolated thunderstorms are possible
which may produce hazardous conditions including gusty/erratic winds,
rough seas, lightning, and reduced visibility.

No additional hazardous marine conditions are anticipated Friday
night through Monday.

&&

.BEACHES...
Increasing west-southwesterly swell on Thursday may produce elevated
surf and a high rip current risk as early as this evening. A long
period westerly swell arrives early Friday morning and generates
high surf into early Saturday morning. Surf of 4 to 7 feet expected
with sets up to 8-10 feet possible for west-facing beaches,
primarily in San Diego County. There will be a high rip current risk
and hazardous swimming conditions. A High Surf Advisory is in effect
and contains more details.

Rounds of moderate to heavy rainfall expected Thursday evening into
early Friday morning. Embedded isolated thunderstorms are possible
which may produce hazardous conditions including lightning and gusty
winds.

&&

.HYDROLOGY...
For San Diego and western Riverside Counties, mostly lighter
rainfall will continue today with the greater totals on the
coastal mountain slopes. For Orange and southwestern San
Bernardino Counties, rainfall will become more widespread this
morning and heavier this afternoon. The cold front is expected to
move southeastward across the area this evening with heavier
precipitation and a slight chance of thunderstorms. Showers will
continue at times for late tonight through Friday, decreasing and
ending from the northwest Friday night.

Through Friday night, additional rainfall and liquid-equivalent
above the snow level is expected to range along the coast from
around 1.5 inch for Orange and northern San Diego Counties to
around 1 inch for southern San Diego County, to 3.5 to 5.5 inches
in the mountains with local amounts to 6 to 8 inches on the
coastal slopes of the San Bernardino County mountains. For high
desert areas, one-third to two-thirds of an inch of rainfall is
expected with one-quarter to one-half inch for the lower deserts.

Isolated heavier rain is possible through today with rainfall
rates 0.40 to 0.50 inches per hour, most likely in the mountains.
For lower elevations, rainfall rates during the day today will be
0.10 to 0.25 inches per hour for the most part. A band of heavier
rain with the cold front will reach Orange and San Bernardino
Counties early this evening, spreading southeastward across San
Diego County before midnight. For lower elevations, peak rainfall
rates will be near 0.40 inches per hour with peak rainfall rates
0.50 to 0.75 inches per hour in the mountains. The 99th percentile
of the HREF has hourly rainfall rates approaching 1 inch per hour
on the coastal slopes of the San Bernardino mountains. There is a
15 to 20 percent chance of thunderstorms for this evening with
the cold front with isolated rainfall of 1 inch per hour.

A snow level near 8000 feet into this evening, will lower to 6000
to 6500 feet early Friday morning, to around 5500 to 6000 feet on
Friday afternoon, and 5000 to 5500 feet by late Friday night.
Below 7500 feet, much of the snowfall is expected from late this
evening through Friday morning with snowfall from around 2 inches
at 6500 feet to as much as 8 inches around 7500 to 8000 feet.
Above 8000 to 8500 feet, there could be as much as 2 to 3 feet of
snowfall from this morning through Friday morning.

Both the San Diego River at Fashion Valley and the Santa Margarita
River at Ysidora are forecast to reach Monitor Stage late tonight
into Friday morning, with a 5 to 10 percent chance of the San
Diego River reaching Minor Flood Stage.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Flood Watch from 10 AM PST this morning through late tonight 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.

     High Surf Advisory from 4 AM Friday to 4 AM PST Saturday for
     Orange County Coastal Areas-San Diego County Coastal Areas.

     High Wind Warning from 10 AM this morning to 4 AM PST Saturday
     for San Bernardino County Mountains.

     Winter Weather Advisory from 10 PM this evening to 10 AM PST
     Friday for San Bernardino County Mountains.

     Wind Advisory from 10 AM this morning to 4 AM PST Saturday for
     Apple and Lucerne Valleys-Riverside County Mountains-San
     Diego County Deserts-San Diego County Mountains-San
     Gorgonio Pass near Banning.

PZ...Small Craft Advisory from 10 AM this morning to 4 AM PST Friday
     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...Munyan