Mount Baldy, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

095
FXUS66 KSGX 231741
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
941 AM PST Mon Dec 23 2024

.SYNOPSIS...
Periods of high clouds expected through the day. Areas of dense fog
are possible within 10 miles of the coast tonight into Tuesday
morning. Gradual cooling is expected through Wednesday. Breezier
and wetter weather is expected for Tuesday afternoon and
overnight. Dry conditions return by Wednesday morning. Gradual
warming is expected Thursday into the weekend.

&&

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

Visible satellite at 9 AM was showing high clouds streaming north
to south across the area with low clouds along the coast. Weak
ridging aloft will build over Southern California today. Highs
today will be a few degrees warmer than today for most locations.
Weak ridging aloft will settle over SoCal by this afternoon. That
will make the marine layer a few hundred feet shallower this
evening and overnight. Areas of dense fog are possible west of
Interstate 15 in San Diego County and west of Interstate 5 in
Orange County. Heights are expected to start to fall early Tuesday
morning ahead of an incoming trough, which would help deepen the
marine layer and spread fog concerns further inland.

The incoming trough of low pressure will move across the West Coast
Tuesday bringing breezy and wet conditions to the area. Onshore
westerly winds will increase Tuesday afternoon, peaking Tuesday
night, strongest in the mountains, through passes, and locally into
the deserts. Current forecast has peak wind gusts of 45 to 55 mph,
with a few local gusts up to 60 mph possible in wind prone
locations. A band of rain showers is expected to start in Orange and
San Bernardino counties late Tuesday afternoon and quickly move to
the southeast, with showers ending in San Diego County very early
Wednesday morning. Winds at 700 mb look like they will range between
40 and 55 knots which will promote orographic enhancement on west
facing mountain slopes. Forecast rainfall totals for the
mountains are 0.20 to 0.40 inches, with the totals closer to 0.40
inches more localized to west facing mountain slopes. For the
coast and valleys rainfall totals are expected to remain mostly
0.10 inch or less, with a few locally higher amounts above 0.10
inches closer to the mountain foothills. Some locations in the
High Desert may accumulate a few hundredths of rain, but
confidence of occurrence is lower compared to areas in and west of
the mountains. A few inches of snow are expected above 7000 ft.
This is a progressive, quick moving trough so dry conditions are
expected for much of the daylight hours on Wednesday.

Temperatures on Wednesday are expected to be a few degrees cooler
than Tuesday. That will bring highs to at or slightly below normal
for this time of year west of the mountains and 3 to 5 degree warmer
than normal in the deserts. A series of Pacific storms are expected
to move across the Northwestern United States into the beginning of
January. Latest global model ensemble guidance is indicating that a
ridge will build from the south over the Pacific ocean which will
largely prevent any of the passing Pacific storms from digging far
enough south to bring us any precipitation. The current forecast has
dry conditions with a gradual warming trend Thursday through Sunday.
There remains some uncertainty in the tracks of the lows passing to
our north, but if any dig south into the Great Basin or
Intermountain West there could be periods of offshore winds.
Currently no guidance is indicating impactful winds through the
forecast period. With the ridge building aloft and continued weak
onshore flow, coastal dense fog could be a concern for later in the
week.

&&

.AVIATION...
231645Z....Coasts/Valleys...Areas of low clouds and FG will continue
through 16-18z within 10 miles of the coast with BKN/OVC bases 600-
1000 ft MSL and tops to 1300-1500 ft MSL, accompanying areas of VIS
2-4SM over higher coastal terrain. Despite general clearing by 18z,
areas of BKN clouds with bases around 1000 ft MSL will likely
continue near the beaches through the afternoon.

Low clouds will push rapidly inland this evening 01-04z (Tues).
Bases may initially start out around 400-700 ft MSL but will likely
rapidly lower to 100-400 ft MSL by 06Z. Along with these, we will
likely see VIs restrictions 0-3 SM along the coast, with areas of
dense fog with VIS <1/2 SM, including likely at KSAN and KCRQ. Most
probable period is 06-12Z, but could start as early as about 04Z and
last as late as 16Z Tue.

A low pressure system moves into the region early Tues morning,
which will lead to gradually rising bases after 12Z Tues with
better improvements after about 15Z, when bases are expected to rise
above 1000 ft MSL and clouds start to push eastward into the
valleys. Bases will continue to rise into the late afternoon, but
VIS 3-6 SM in BR could last into the afternoon, and overcast
conditions continue along the coast all day. Some light drizzle is
possible Tuesday morning, but rain not likely until 00Z Wed, after
which precipitation will spread from west to east across the region
through about 05Z. Heavier showers will lead to locally lowered
bases 1000-2000 ft MSL and VIS 2-5 SM. Clouds will start to break up
and clear late this evening.

.Mountains/Deserts...SCT-BKN high clouds mostly at/above 20,000 ft
MSL with unrestricted VIS will prevail through Tuesday morning.
Clouds at 3000-6000 ft MSL or so will move into after 20Z Tues,
leading to terrain obscurations. Precipitation will then move across
the area from west to east after 00Z through 06-08Z. Locally lower
CIGs and VIS under showers. Deserts will see some cloud cover but
very likely remain dry. Additionally, winds will pick up over ridges
and higher terrain after 18Z Tue, with gusts to 30-45 kt and mod to
strong updrafts/downdrafts near the mountains in the evening.

&&

.MARINE...
Long period (16-20 second) west to northwest swells (280-290 deg)
will continue to move through the coastal waters through Wednesday,
with the highest swells in the outer coastal waters where a Small
Craft Advisory is in effect. Seas of 8-12 feet for the outer coastal
waters and 7-9 feet within 30 NM of the coast. Wind gusts of 20-30
knots are expected Tuesday night in the outer coastal waters.
Additional long period swells will continue to move into the region
the second half of the week, but wave heights will be a bit lower at
6-9 feet.

&&

.BEACHES...
Long period (16-20 second) west to northwest swells (280-290 deg)
will produce high surf of 6-12 feet with locally higher sets through
Wednesday. Highest surf expected for west facing beaches. This will
make swimming hazardous and pose a minor coastal flooding threat.
Elevated surf will continue late in the week as additional, albeit
somewhat smaller, swells occur. See the High Surf Advisory for more
details.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory until 4 AM PST Wednesday for Orange County
     Coastal Areas-San Diego County Coastal Areas.

     Wind Advisory from 4 PM Tuesday to midnight PST Tuesday night
     for Apple and Lucerne Valleys-Coachella Valley-Riverside
     County Mountains-San Bernardino County Mountains-San Diego
     County Deserts-San Diego County Mountains-San Gorgonio Pass
     Near Banning.

PZ...Small Craft Advisory until 4 AM PST Wednesday for Waters from
     San Mateo Point to the Mexican Border Extending 30 to 60 nm
     out including San Clemente Island.


&&

$$

PUBLIC...CO
AVIATION/MARINE/BEACHES...CSP