High Wind Watch 3, NWS San Diego, CA

Area Forecast Discussion
National Weather Service San Diego CA
926 AM PST Thu Feb 29 2024

.SYNOPSIS...
A large low pressure system over the northeast Pacific will move
slowly inland along the US West Coast through the weekend. Gusty
winds are expected in the mountains, desert mountain slopes, and
into the deserts. Along with the strong winds in the mountains,
periods of snow are expected above 4500-5000 ft. West of the
mountains, showers are expected Friday through Sunday, with the
best chances of precipitation on Saturday. A deep marine layer
will result in areas of drizzle (and even light rain in some
locations) tonight into Friday morning. Below average temperatures
will maintain themselves into next week. There are additional
chances of precipitation around the middle of next week.

&&

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

A very deep marine layer this morning has produced areas of drizzle
and even light rain in some locations. Any rain accumulations over
the past 12-hours have been light at 0.01 to 0.03 inches. The
marine layer is expected to maintain its depth tonight into Friday
morning with areas of drizzle and light measurable rain again
possible. Increased onshore flow has enhanced southerly winds
through the Cajon Pass and westerly winds through the San Gorgonio
Pass this morning. Strongest wind gusts in those areas since
midnight have been mostly under 40 mph, with a few local gusts up
to 45 mph. Similar winds are expected Friday morning before an
increase in winds Friday night into the weekend. Below average
temperatures are expected today and Friday, with continued below
average temperatures this weekend.

As the broad area of low pressure digs south into the Great Basin
Friday night, winds will begin to increase more significantly over
the mountains, desert mountain slopes, and into the deserts. Winds
are expected to be strongest Saturday evening into Sunday as the low
pressure system slowly moves east. Peak wind gusts of 70 to 80 mph
are expected on mountain ridges and desert mountain slopes, with
gusts 40 to 60 possible in the deserts with the strongest winds in
the High Desert and below the San Gorgonio Pass. Latest guidance
has winds peaking overnight Saturday, slowly diminishing into
Sunday. These strong gusty winds will make travel difficult at
times, mainly for high profile vehicles traveling in those windy
locations and for all vehicles traveling in the mountains.

Periods of precipitation are expected from the coast to the
mountains Friday afternoon into Sunday. Rainfall is expected to be
scattered and showery in coverage. Light to moderate rain is
expected, with rain rates peaking around 0.25 inches per hour at
times. Best chance of rain is on Saturday. Through Sunday rain
totals for Orange and southwestern San Bernardino Counties is
expected to range from around one-quarter inch near the coast to
one-half to one inch in the mountains. For San Diego and western
Riverside Counties, rainfall is expected to range from one-quarter
inch for northern San Diego County and southwestern portion of
the Inland Empire to less than one-tenth inch for southern San
Diego County to one-quarter to one-half inch in the mountains.

Periods of snow are also expected. Most of the snow will
accumulate in the San Bernardino County mountains and on the
higher peaks of the Riverside County mountains. Snow levels around
6000 feet on Saturday are expected to fall to around 4500-5000
feet on Sunday. Precipitation is expected to be tapering off as
snow levels drop to their lowest levels. It is looking unlikely
the San Diego county mountains will see accumulating snowfall.
Current forecast has 5 to 9 inches of snow above 7000 ft, 2 to 5
inches of snow between 6000-7000 ft, and a trace to an inch
between 5000-6000 ft. Travel will be hazardous in the mountains,
especially in the San Bernardino and Riverside county mountains
where periods of snow and gusty winds will reduce visibility. In
addition, this storm is colder in nature so snow is more likely to
stick on roads, resulting in slippery road conditions.

Showers are expected to decrease on Sunday morning and end over the
mountains in the afternoon. Drier conditions with a few degrees of
warming for Monday into Tuesday, but below average temperatures will
continue. There are additional chances for precipitation around the
middle of next week. Low confidence in details and timing.

&&

.AVIATION...
291655Z...Coast/Valleys...BKN-OVC low clouds 2000-3500 feet MSL with
tops to 4500-5000 feet will continue this morning. Locally SCT
clouds making an appearance at coastal TAF sites 21Z-01Z today.
Otherwise, 60-80% chance of 2500-3500 BKN cigs prevailing across
much of the coastal basin through tonight. -DZ possible again
tonight into Friday morning 06-16Z, locally and temporarily dropping
cigs and vis.

Mountains/Deserts...Mostly clear with unrestricted today. Low clouds
and fog climbing up coastal slopes tonight, obscuring some terrain
up to 6000-7000 feet MSL. SW-W wind gusts 25-35 kt on the desert
mountain slopes and into the deserts after 20Z creating MOD
UDDFS/LLWS.

&&

.MARINE...
No hazardous marine conditions through Friday. Areas of showers
expected later on Friday through Saturday with a low to moderate
chance of seeing winds reach small craft conditions on Saturday.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

PUBLIC...CO
AVIATION/MARINE...APR