Wind Advisory 36, NWS San Diego, CA

Area Forecast Discussion
National Weather Service San Diego CA
121 PM PDT Sun Jun 11 2023

.SYNOPSIS...
Cool conditions, gusty onshore winds and scattered showers are
expected today. Isolated thunderstorms will be possible over the
mountains and High Desert this afternoon. Lingering, light rain
showers look to persist into Monday as the low pressure system
pivots through Southern California and moves into the
Intermountain West. A persistent low looks to set up off the coast
of Southern California for much of this week, maintaining onshore
flow and night and morning low clouds, though slow warming is
expected through at least the middle of the week. Uncertainty
increases towards the end of the forecast period, though below-
normal highs look to continue through the first two-thirds of
June.

&&

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

A 568 DM low is centered over San Bernardino County today. 500 mb
analysis shows a vorticity maximum moved over Southern California
early this morning which triggered scattered thunderstorms over
the deserts, with cells clipping far northeastern portions of our
High Desert; this is where the most persistent activity has
occurred so far. Elsewhere, mainly light, scattered rain showers
have been noted across the coast and valleys, with most locations
picking up a trace to 0.1" so far.

A second vorticity max is rounding the base of the trough this
afternoon into northern Baja, and this will lead to the next
round of scattered rain showers. Activity will mainly be focused
on San Diego County, the mountains and the High Desert. The only
appreciable instability will be in the mountains (where upsloping
occurs) and the High Desert; a few cells have fired this afternoon
but have been short-lived thus far. For the rest of today, most
areas that see showers will see additional accumulations under
0.1", though heavier rain rates to 0.25"/hr will be possible if
thunderstorms develop. In addition to rain, winds will pick up
this afternoon and peak into the early evening hours, with maximum
wind gusts of 40-55 mph over the mountains and desert slopes, and
locally higher wind gusts possible in wind-prone passes and
canyons.

The third, and final, wave looks to advect into Southern
California Monday morning, leading to the last push of light
showers. This activity will be more sparse and moisture looks to
decrease through the day, putting an end to accumulating rainfall.

Today will be the coldest day of the week. The ECMWF EFI shows
values of -0.5 to -0.8 for highs today, showing an anomalously
cold core to this storm system. Highs will range 5-10 degrees
below normal for the coast, and highs as much as 15-25 degrees
below normal for the valleys, mountains and deserts. Highs will
range in the 60s for the coast and valleys, the 40s and 50s in the
mountains, the low-70s in the High Desert and the mid-80s in the
lower deserts.

As the center of the storm system moves east early this week,
longwave troughing persists across the West Coast as a closed low
forms to our southwest and lingers through much of the week.
Weakening negative height anomalies on ensemble guidance support
slow warming through at least of the middle of the week, with
highs rising a few degrees each day, though will still likely
remain below seasonal averages. Persistent onshore flow will
maintain a healthy marine layer with night and morning low clouds
covering the coast and valleys.

Details become more fuzzy by the end of the forecast period. The
00z cluster analysis continues to maintain the presence of the
closed low to our southwest as well as a building ridge somewhere
near the Four Corners region or the Southern Plains. If the ridge
is able to nudge farther west, temperatures will continue to warm
for the end of the week. If the ridge sets up farther east and the
low is closer to Southern California, warming will stall. GEFS
solutions support a stronger ridge farther west while ECMWF
clusters maintain the cooler pattern and return of stronger
negative height anomalies. As the forecast currently stands,
below-normal temperatures will persist through the first two-
thirds of June.

&&

.AVIATION...
111930Z...BKN-OVC clouds layers with bases 2500-3500 feet MSL and
additional SCT-BKN layers 1000-2000 feet MSL with tops to 6000 feet
MSL continuing along/west of the mountains through Monday morning,
obscuring coastal mountain slopes. DZ and ISO-SCT -SHRA with local
vis 2-4 SM and CIGS down to around 800-1000 ft MSL in heavier
showers, with the greatest coverage through 02Z Monday.

Additional SCT SHRA and isolated TSRA over the San Bernardino
Mountains and deserts this afternoon with CB bases near 12,000 feet
MSL and tops to 25,000 feet MSL, diminishing after 03Z Monday.
Otherwise SCT-BKN clouds at/above 8,000 feet MSL and unrestricted
vis over the deserts.

West winds 15-25 kt with gusts 30-45 kt will continue through 12Z
Monday with moderate up/downdrafts over/east of the mtns.

&&

.MARINE...
No hazardous marine conditions are expected through Thursday.

&&

.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...EA
AVIATION/MARINE...Connolly

Special Weather Statement
National Weather Service San Diego CA
207 PM PDT Sun Jun 11 2023

CAZ055-060-112145-
Apple and Lucerne Valleys CA-San Bernardino County Mountains CA-
207 PM PDT Sun Jun 11 2023

...A strong thunderstorm will impact portions of San Bernardino
County through 245 PM PDT...

At 206 PM PDT, Doppler radar was tracking a strong thunderstorm over
Hwy 18 Between Baldwin Lake And Lucerne Valley, near Big Bear City.
This storm was nearly stationary.

HAZARD...Winds in excess of 30 mph, pea size hail, and frequent
         lightning.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Big Bear City, Lucerne Valley, Hwy 18 Between Baldwin Lake And
Lucerne Valley, and Baldwin Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3439 11685 3433 11675 3426 11684 3432 11692
TIME...MOT...LOC 2106Z 008DEG 1KT 3432 11685

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...30 MPH

CO