Areal Flood Advisory 21, NWS San Diego, CA

495 
WGUS86 KSGX 282335
FLSSGX

Flood Advisory
National Weather Service San Diego CA
435 PM PDT Wed Jul 28 2021

.Thunderstorms have weakened. Runoff will continue.

CAC073-290115-
/O.CON.KSGX.FA.Y.0021.000000T0000Z-210729T0115Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Diego CA-
435 PM PDT Wed Jul 28 2021

...THE ARROYO AND SMALL STREAM FLOOD ADVISORY REMAINS IN EFFECT 
UNTIL 615 PM PDT THIS EVENING FOR NORTHEASTERN SAN DIEGO COUNTY...

At 435 PM PDT, Earlier doppler radar indicated heavy rain due to 
thunderstorms. This will cause arroyo and small stream flooding. 
Between 0.5 and 1 inch of rain has fallen.

Some locations that will experience flooding include...
Borrego Springs, Borrego Palm Canyon, Ranchita, Warner Springs, Hwy 
S2 Between Hwy 79 And Hwy 78, Hwy S22 Between Ranchita And Borrego 
Springs, Hwy 79 Between Santa Ysabel And Warner Springs, Hwy 79 
Between Warner Springs And Oak Grove, Los Coyotes Indian Reservation 
and Santa Ysabel Indian Reservation.

Palm Canyon and Chuckwalla Wash  is the most likely place to 
experience minor flooding near Highway 78.

Additional rainfall amounts up to 0.25 inches are expected over the 
area. This additional rain will result in minor flooding.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 3342 11668 3343 11651 3331 11642 3318 11641
      3319 11665 3322 11667 3322 11666

$$

Tardy

Area Forecast Discussion
National Weather Service San Diego CA
132 PM PDT Wed Jul 28 2021

.SYNOPSIS...
Monsoonal moisture will continue a slight chance of thunderstorms
this afternoon for the mountains and high desert. Similar weather
is expected Thursday. A bigger influx of monsoonal moisture
Friday through Saturday will bring more clouds, better chances for
more widespread showers and thunderstorms, and high temperatures
not as hot. Drier weather arrives Sunday, with a warming trend
through the middle of next week. Areas of nocturnal coastal
cloudiness will continue.

&&

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

A few thunderstorms have erupted right over the mountain ridges
and Joshua Tree NP area. These will continue to form and
dissipate this afternoon, while drifting into mainly the high
desert. Coastal clouds were rather patchy this morning and have
cleared out nicely. Copy and paste today's weather into Thursday
regarding the chance, location and timing of both the
thunderstorms and the coastal clouds. On Friday, more moisture
pours into the region from the southeast. However, this moisture
is higher up in the atmosphere, somewhat limiting the instability.
The thicker moisture and more abundant clouds will bring a slight
chance of showers early Friday, followed by a chance of afternoon
thunderstorms across mountains and deserts and far inland
valleys. This interesting wave of moisture continues to flow in
Friday evening through Saturday morning. Nocturnal thunderstorms
are very possible in Imperial Valley and showers could spill into
our eastern desert regions late Friday and/or early Saturday. The
surface heating Saturday afternoon will destabilize the atmosphere
for the more traditional chance of thunderstorms in the mountains
and deserts during the afternoon Saturday. Nearly all model
guidance starts pushing out the moisture by late Saturday, leaving
Sunday dry. The drier southwest flow appears stay in place, too
dry for precipitation Sunday through Wednesday. Marine layer
coastal clouds should make a better recovery tonight, but could
get disrupted again this weekend. Look for areas of coastal clouds
each night and morning. Next week the drier air and high pressure
aloft will continue for a few days, allowing for a warming trend.
Temperatures will peak Thursday this week, cooling down with more
clouds and higher humidity Friday and Saturday, followed by a
warming trend Sunday through midweek. Daytime highs Thursday and
next week should be a few degrees above average, which is over
110 in the lower deserts and near 100 in the Inland Empire.

&&

.AVIATION...
282015Z...Coast/Valleys...FEW clouds around 1000 ft MSL at some
beaches this afternoon. Patchy BKN-OVC low clouds expected along the
coast after 09Z Thu, mainly in San Diego County. Low clouds could
locally spread up to 10 mi inland. Bases will be 500-1000 ft MSL,
locally down to 300 ft MSL. Vis will be locally reduced to 2-4 SM in
BR/HZ where stratus nears higher coastal terrain. Low confidence any
cigs will form at KSNA. Low clouds will clear 15-17Z Thu.

Mountains/Deserts...Slight chances of SHRA/TSRA through 01Z Thu,
mainly over the Riverside and San Bernardino Mountains into the High
Desert. CB bases near 7000 ft MSL and tops to 30,000 ft MSL. Gusty
outflow winds and reduced vis of 2-4 SM in/near TSRA.

&&

.MARINE...
No hazardous marine weather is expected through Monday.

&&

.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...MM
AVIATION/MARINE...CO

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN DIEGO CA
223 PM PDT WED JUL 28 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0330 AM     FLASH FLOOD      3 E MECCA               33.58N 116.01W
07/26/2021                   RIVERSIDE          CA   EMERGENCY MNGR

            DELAYED REPORT. RADAR ESTIMATED 2 TO 2.5
            INCHES OF RAINFALL AT THE MOUTH OF BOX
            CANYON WHICH CAUSED FLASH FLOODING AT THE
            ENTRANCE OF BOX CANYON ROAD AND ALONG
            PAINTED CANYON ROAD. THERE WERE A COUPLE
            VEHICLES INVOLVED WITH THE FLOODING WHICH
            CAUSED A ROAD CLOSURE. LOCATED SOUTH OF I-10
            AND NORTH OF HIGHWAY 111.

&&

AOT