Harbison Canyon, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

327
FXUS66 KSGX 142108
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
108 PM PST Thu Nov 14 2024

.SYNOPSIS...
An area of low pressure will drift southward, bringing in much
cooler air, windier conditions and a chance for precipitation
across Southern California later tonight through Saturday. Snow
showers are expected across the mountains, where areas above 5,500
feet will see a few inches of fresh powder. Subtle warming and
drying will occur by Sunday and Monday. A trough and a ridge will
dance across the West, which may bring another round of elevated
Santa Ana winds by the middle of next week.

&&

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

.SHORT TERM (Through Saturday)...

GOES imagery shows scattered clouds over the NE Pac moving
southeastward toward our region this afternoon. A trough will
continue to deepen, pushing into our area later tonight. The warm
days will leave us for a bit as much cooler air moves in. High
temperatures by Friday will be around 10-20 degrees cooler than
they are today. Biggest change will be across the mountains, where
50s&60s today will drop to 30s&40s by Friday afternoon. Chilly
mornings are also expected this weekend, with widespread 40s for
areas west of the mountains and teens and 20s across higher
elevations. Please protect pipes, people, and pets!

Rain showers currently over the Bay Area will drift toward our
area as early as this evening. Scattered showers will occur mainly
from the coastal slopes to the beaches tonight into Friday where
the best chance of precipitation will occur. NW flow aloft from
this system will favor very light totals for OC and the IE, a bit
more across San Diego county, where some parts of the SD valleys
may receive near one quarter of an inch. The coastal slopes will
see the highest totals, some close to an inch in portions of the
San Bernardinos. In terms of snowfall, confidence is highest in
seeing greatest snow totals in elevations above 5,500 feet. This
has led to a Winter Weather Advisory across these norther mountain
areas. Most areas will see snowfall near 1 to 3 inches in total,
some closer to 4 inches. Snow levels will drop throughout the day
on Friday, so some areas near 4,000 feet may see some flakes fly
by Friday night into Saturday with minor accumulations. Confidence
is a bit less on when the system moves out as models differ in
precip totals by Saturday, but kept small chances in for this time
period as postal frontal activity may bring scattered clouds and
light showers.

West winds will also increase with this system later tonight
through Friday. Chances are moderate to high in seeing wind gusts
over 35 MPH for the mountains and deserts. Chances are low to
moderate in seeing winds over 30 MPH at the coast. Winds will
weaken on Friday night.

&&

.LONG TERM (Sunday into mid next week)...

The system will push out by Sunday, leading to drier weather. A
secondary trough from the north will scoot by, keeping wet weather
to the north but limiting any major warming for Sunday and Monday.
A ridge will amplify across the NE Pac into the West by Tuesday
into the middle of next week. Depending on where the early week
trough goes will determine how strong of a Santa Ana wind event
will occur between these two systems. Model guidance continues to
be quite widespread. Confidence is increasing on seeing Santa Ana
winds, but exact strength of these winds is still very uncertain.
EPS guidance favors stronger winds as the trough dives into the
Southwest, while others favor a more ridging pattern, which would
lead to less wind. Please keep an eye on this as winds have the
potential to be strong.

&&

.AVIATION...
142045Z...Mostly clear skies and VFR conditions continue through
late this afternoon. Low clouds moving onshore into coastal sites
after about 07Z Fri and into inland valleys through 11-15Z. Bases
1500-2000 ft MSL becoming 2400-3000 ft MSL through Thursday night.
Isolated -SHRA developing around 15/07Z this evening becoming more
widespread through Fri morning. Local VIS reductions 4-6 SM and
lower CIGs 1200-2000 ft MSL possible in showers.

West to northwest winds picking up after 05Z Fri with areas of winds
25-30 kt over mountains and deserts. Moderate to strong updrafts
over the mountains with mountains becoming obscured below 6000 ft
MSL in clouds and showers.

&&

.MARINE...
Northwest winds strengthen this afternoon ahead of a Pacific weather
system, bringing steep, wind-driven seas and likely hazardous marine
conditions. A Small Craft Advisory is in effect this afternoon
through late Saturday night. Winds will increase outer coastal
waters this afternoon to 15-20 knots with gusts to 25 knots,
reaching into the nearshore inner waters tonight into early Friday
morning. Winds peak Friday afternoon at 20 to 25 knots with gusts to
30 knots before gradually diminishing late Friday into Saturday.
Intermittent gusts to about 35 knots are also possible (40% chance)
near San Clemente Island Friday. Strong winds will bring steep, wind-
driven seas late Thursday through late Friday night, peaking at 6 to
9 feet Friday. Winds weaken Saturday morning as seas diminish
Saturday into Sunday.
&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Winter Weather Advisory from 9 PM this evening to 10 PM PST
     Friday for Riverside County Mountains-San Bernardino County
     Mountains above 5,500 feet.

PZ...Small Craft Advisory until 4 AM PST 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...APR
AVIATION/MARINE...Small