Small Craft Advisory 5, NWS San Diego, CA

Area Forecast Discussion
National Weather Service San Diego CA
933 AM PST Sat Feb 3 2024

.SYNOPSIS...
A brief break in active pattern will occur today with a mix of
clouds and sun and cool weather. A slow moving low pressure
system with moisture from an atmospheric river may bring some
lighter precipitation as early as tonight or early Sunday with the
precipitation becoming heavy at times for late Sunday or early
Monday and continuing into Tuesday and possibly Wednesday with
lesser chances for precipitation continuing into Friday or early
Saturday.

&&

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

.Morning Update...
Satellite imagery shows banding of low clouds for areas west of
the mountains with valley fog clearing. High clouds will begin to
make their way into SoCal later this morning and afternoon, giving
us a brief reprieve from precipitation. We hope you are able to
enjoy the sun or get outside while you can!

No major changes this morning with the forecast. Sunday will see
the beginning of moderate to heavy precip from north to south
throughout the day, with confidence still low on exact onset
timing. Gusty winds will occur ahead of the incoming storm on
Sunday as well, where wind advisories are in effect for coastal
areas and the high desert for gusty south winds. Winds will gust
near 35-40 MPH for the coast and 45-60 MPH across the SBD mtn
desert slopes into the high desert, so travel carefully if out and
about in this area.

.Previous Discussion (453 AM Saturday)...

.SHORT TERM (Today through Monday)...

A low pressure system will intensify off the California coast
today and Sunday, then move slowly eastward for Monday and
Tuesday. Some generally lighter precipitation will spread
northward across portions of southern California tonight. Heavier
precipitation along the central California coast will move slowly
eastward into southern California on Sunday and Sunday night with
the axis of heaviest precipitation centered across Ventura County
Sunday afternoon and Los Angeles County during the late afternoon
into Sunday night, then moving eastward into San Diego County
Sunday night and early Monday where it may stall into Monday
evening.

The atmospheric river is directed into San Diego County from late
tonight into Monday with the peak integrated water vapor transport
early Monday. Widespread moderate to heavy precipitation is
expected for portions of southern California for Sunday through
Tuesday with the heaviest rainfall centered across southwestern
California around Monday.

The snow level will rise to 7500 to 8000 feet on Monday morning,
then gradually fall to around 4500 feet for early Wednesday.
Strong south to southeast winds will develop on Sunday as surface
low pressure intensifies off the central California coast. These
winds will continue into Monday morning with the strongest winds
for the coastal waters and coastal areas and over the San
Bernardino County mountains and deserts.

Ensemble output for rainfall shows a single higher peak centered
around Monday for areas from Orange County northwestward with a
narrower spread in the amounts. While for San Diego County, there
is a broader peak from Monday into early Wednesday with greater
spread in amounts.

As seen in recent events in southern Los Angeles County into far
northwestern Orange County on Thursday and in southeastern San
Diego last week, there can be more localized areas of more
intense rainfall over short periods of time. The local NAM-bounded
WRF showed some clues of the heavier rainfall in San Diego last
week with narrow bands or west to east oriented rainfall exceeding
2 inches in an hour though with not unexpected errors in the
timing and placement.

The latest run of the local NAM-bounded WRF has localized amounts
of almost 5 inches in two hours in southern Los Angeles County
between 3 AM and 6 AM Monday from narrow bands of intense rainfall
moving from south to north as the bands move slowly eastward
across southern Los Angeles County into northern Orange County.

One shouldn't focus too much on the timing or placement of such
intense rainfall because it will probably differ from the model
placement if it occurs. However, it does provide an indication of
the type of intense rainfall that could occur over a smaller area
within a few hours within the broader area of moderate to heavy
rainfall.

&&

.LONG TERM (Tuesday through Friday)...
Moderate to locally heavy precipitation will continue into
Tuesday and possibly early Wednesday for portions of southern
California. The model clusters that are relatively wetter each day
for southwestern California are those that are slower with the
movement of the low pressure system and a little farther west with
the placement of the upper trough. Chances for generally less
significant rainfall could continue into Thursday and Friday,
generally from low pressure systems moving southeastward across
the area on a little more inland track with much more spread in
the model timing and track of such potential systems.

The potential for heavy snow in portions of the mountains is
greatest for Monday night and Tuesday as heavier precipitation
continues and snow levels fall.

&&

.AVIATION...
031700Z...Coast/Valleys/Mountains...SCT locally BKN clouds with
bases 2500-4000 ft MSL and tops to 8000 ft MSL becoming locally BKN
only mountain areas after 03/20z this afternoon and SCT elsewhere.

Deserts...SCT clouds with bases AOA 10000 feet MSL through this
evening with unrestricted surface VIS.

&&

.MARINE...
South to southeast winds will increase Sunday and Monday, with gusts
25-30 kt, along with seas building to 10 to 12 ft, locally up to 14
ft possible. Strong winds and choppy/steep seas will create
hazardous boating conditions for Sunday morning through much of
Monday. Periods of moderate to heavy rain are expected Sunday night
through Tuesday as well as a chance of thunderstorms Sunday night
into Monday.

&&

.BEACHES...
An incoming southwest swell from 240 degrees of 8-12 feet with 8-12
second period is expected generate high surf Sunday night into
Monday. Surf of 6 to 8 feet, with sets to 10 feet expected. Strong
rip currents and hazardous swimming conditions are expected.

There is a chance of thunderstorms at beaches starting Sunday night
and continuing into Monday.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory from 8 PM Sunday to 10 AM PST Monday for San Diego
     County Coastal Areas.

     Flood Watch from late Sunday night through Wednesday morning for
     San Diego County Coastal Areas-San Diego County Deserts-San
     Diego County Mountains-San Diego County Valleys.

     Flood Watch from Sunday afternoon through Tuesday afternoon for
     Apple and Lucerne Valleys-Coachella Valley-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 Gorgonio
     Pass Near Banning-Santa Ana Mountains and Foothills.

     Winter Storm Watch from this evening through Tuesday afternoon
     for Riverside County Mountains-San Bernardino County
     Mountains.

     Wind Advisory from noon to 10 PM PST Sunday for Apple and
     Lucerne Valleys.

     Wind Advisory from noon Sunday to 10 AM PST Monday for Orange
     County Coastal Areas-Orange County Inland Areas.

PZ...None.

&&

UPDATE/PREVIOUS PUBLIC...APR/17
AVIATION/MARINE...Small