*Annual Rainfall is based on the California Water Year,|
which runs from October 1 through September 30.
FXUS66 KSGX 102041
Area Forecast Discussion
National Weather Service San Diego CA
141 PM PDT Sat Apr 10 2021
Mild conditions will continue this weekend, with overnight and
morning low clouds persisting at the coast. A developing low to
our north will enhance the onshore flow early next week, forcing
temperatures to fall to below normal values by Tuesday, and
brining a surge of stronger westerly winds to the mountains and
deserts into Wednesday. The marine layer will deepen, perhaps just
enough to generate some a few light sprinkles Monday night into
Tuesday morning west of the mountains. Gradual warming will
follow later in the week, with weaker onshore winds and a
shallower marine layer.
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
Our mild spring weather continues today with temperatures climbing
to around 5 degrees above normal across the interior, and locally
10 degrees above average in the Coachella Valley. Skies are clear
save for a few passing high clouds that will keep streaming
overhead into this evening. Marine layer clouds will join the
party again tonight, and given signs of a developing coastal eddy,
should be slightly deeper resulting in greater coverage into the
valleys relative to last night. Patchy fog should make an
appearance once again Sunday morning, affecting higher elevations
of the coastal zones and portions of the valleys. The first hint
of a larger upcoming cooling trend will arrive Sunday as highs
nudge downward a couple of a degrees. Partially sunny skies are
expected, with a more extensive high cloud deck. Marine layer
clouds will fill the coastal basin once more Sunday night.
On Monday, a low pressure system will dig southward from the
PacNW and into northern Nevada, strengthening our onshore flow and
ultimately breaking our monotonous weather pattern. West winds
will pick up in the afternoon across our desert slopes, with the
decrease in temperatures becoming more pronounced as highs
fall to seasonal averages or slightly below west of the mountains.
Onshore pressure gradients will tighten Monday night into Tuesday
as the low anchors over the northern Great Basin. This will lead
to a significantly deeper marine layer spreading well inland to
the coastal mountain slopes. The deepening may be sufficient to
squeeze out a few drops west of the mountains (we're talking a few
hundredths of an inch) overnight into Tuesday morning, but even
that is not guaranteed. In fact, measurable precipitation is now
the minority solution among EC and GFS ENS members, as opposed to
a couple of days ago when nearly all members indicated at least
one or two hundredths. Regardless, temperatures will continue to
tumble across the region Tuesday as highs lower to around 10
degrees below normal west of the deserts. Winds will remain gusty,
particularly Tuesday afternoon/evening, with gusts 40 to 50 mph
across desert slopes and east-west passes, locally higher for
windy and remote sites.
Winds should lighten up slightly by Wednesday although wind-prone
areas will remain rather gusty. Temperatures will start to
plateau with the exception of the deserts, which will be a few
degrees cooler. As weaker zonal flow takes hold aloft, the cool
conditions will give way to a steady warming trend late week and
into the weekend as we inch closer to above-normal temperatures.
The marine layer will persist at the coast, but will be
considerably shallower than midweek. Ensemble systems appear to be
in good agreement in the long range, with essentially no
indications of any significant precipitation heading into the
second half of the month.
102000Z...Coast/Valleys...Mostly clear skies will prevail this
afternoon except for local stratus near the San Diego County beaches
with cigs around 1500 ft MSL. Stratus will redevelop this evening,
mostly 04Z-07Z with bases 1100-1700 ft MSL and tops to 2000 ft MSL
with higher terrain obscured. Most vis will be 5+ miles below the
cloud bases. Clearing will likely be slower Sun, mostly 17Z-20Z.
Mountains/Deserts...FEW-SCT clouds at/above 20,000 feet MSL will
continue through Sun morning, with unrestricted vis.
Breezy west-northwest winds with peak gusts 20-25 knots will occur
late this afternoon and evening over the outer coastal waters (30-60
NM from the coast). The strongest winds will be near San Clemente
Island. A Small Craft Advisory remains in effect through 9 PM this
evening. Breezy west-northwest wind gusts to 20 knots will occur
each afternoon and evening Sunday through Tuesday but should remain
below Small Craft Advisory criteria. &&
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
PZ...Small Craft Advisory until 9 PM PDT this evening for Waters from
San Mateo point to the Mexican Border Extending 30 to 60 nm
out including San Clemente Island.