920
FXUS66 KSGX 231714
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
914 AM PST Sun Feb 23 2025

.SYNOPSIS...
A warming trend will occur through the middle of the week, with
temperatures reaching 10-20 degrees above normal by Wednesday.
Elevated Santa Ana winds are expected to make a return by
Wednesday and Thursday. A notably cooler weather pattern will
occur by Friday into next weekend with increased chances for light
precipitation across Southern California.

&&

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

.UPDATE...
Low clouds and fog developed offshore this morning,
and satellite shows that these clouds are quickly clearing. With
no further impacts expected, the Marine Weather Statement has been
expired at the top of the hour. Light offshore flow this morning
will be replaced with diurnal onshore flow, and a similar pattern
follows in the coming days. Weak upper level ridging building in
pushes temperatures above normal for the majority of the week,
with dry Santa Ana winds developing Wednesday/Thursday and
shooting temperatures to 10-20 degrees above normal. Cooler
weather arrives late week as a cutoff low moves across Southern
California, struggling to provide much in the way of precipitation
given the drier pattern the previous days. Confidence remains low
for meaningful precipitation through the weekend despite an
additional system moving into California on Sunday. Even if no
precipitation is provided with these incoming systems, cooler
temperatures closer to near normal should arrive by Friday.

.PREVIOUS DISCUSSION FROM 308 AM FEB 23...
Another early morning with a light offshore wind pattern is
continuing for your weekend, which is helping to keep low clouds
and fog mainly off the coast at this hour. Satellite shows a few
patches of clouds starting to form off of San Diego County. This
trend will continue through the morning hours with intermittent
foggy conditions near the beaches, becoming mostly clear by the
afternoon. High pressure over the East Pac will maintain our
warmer weather pattern today into Monday. The marine layer will
continue to be thin, so low clouds and fog are possible at the
coast again Monday morning.

By Monday through Wednesday, a thermal ridge will amplify across
the desert southwest, where 850mb temps peak near 18C. This will
first start to be felt across the deserts on Monday with
increasing temperatures; plentiful 70s to near 80 expected across
the high desert and 80s in the lower deserts. NBM depicts around
a 25% chance of Palm Springs reaching 90 degrees. Slight warming
will occur by Tuesday for areas away from the coast with higher
confidence in highs in the lower 90s in the lower deserts and low
to mid 80s for valleys west of the mountains. The ridge over the
East Pac will amplify across the West Coast as upper level winds
turn offshore by Wednesday. This will lead to the warmest day of
the week overall. Confidence is growing that some inland valleys
west of the mountains will reach 90 degrees, the first time this
year. The calendar may read February, but make sure to seek shade
and take rest breaks with water if having to be outside for long
periods of time.

The amplified ridge will begin to become cutoff over the Great
Basin as an area of low pressure pushes toward California by
Thursday. Model spread in temperatures continue to be seen, but I
have leaned toward warmer temps as winds become stronger from the
NE/E as the pressure gradient tightens between the high to the
north and the low to the west. Thursday could see the strongest
Santa Ana winds of the week. Model spread is evident as some
members show a weaker event, while others show a more moderate
event, especially for east-west passes in Riverside and San Diego
counties. This event will be short-lived as the low off the coast
will push inland on Friday. This will lead to greater onshore
flow and cooling across the region, where temperatures will fall
around 5 degrees for most areas from Thursday to Friday, closer
to 10 to even 15 degrees for valleys west of the mountains.
Ensembles begin to show an increase chance for precipitation as
this low moves ashore, but things are not looking too good for
anything substantial. The best chance of precip will be across
western San Diego county if any rain drops decide to fall out of
the sky for us.

Hope is not lost, however, as forecast models show another
stronger area of low pressure slated to move into the West Coast
by next weekend. As we are still about a week away from this,
there is large spread in model solutions on where this low goes,
notably if it will elongate far south enough toward our region to
give us precipitation. NBM chances look adequate in the forecast
for now, giving us a low to moderate chance for some wetter
weather as we head into the month of March.


&&

.AVIATION...
231645Z...Coast...Low clouds have struggled to
develop this morning, with only a small patch of clouds still
remaining off the coast of San Diego County out over the waters.
Bases in these highly localized patches are 200-400ft MSL with
associated fog leading to VIS 0-2SM. Low clouds and fog are
possible once again tonight into Monday morning, but look to be
very patchy and isolated as they were this morning.

Valleys/Mountains/Deserts...Mostly clear skies with unrestricted VIS
will prevail through Monday.

&&

.MARINE...
Patchy dense fog is possible again tonight into Monday morning.
Otherwise, no hazardous marine conditions are expected through
Thursday.

&&

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

&&

$$

PUBLIC...Zuber
AVIATION/MARINE...Stewey