Flash Flood Warning 1, NWS San Diego, CA

834 
WGUS76 KSGX 310134
FFSSGX

Flash Flood Statement
National Weather Service San Diego CA
634 PM PDT Sun Jul 30 2023

CAC071-310144-
/O.CAN.KSGX.FF.W.0001.000000T0000Z-230731T0315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-
634 PM PDT Sun Jul 30 2023

...FLASH FLOOD WARNING FOR THE EL DORADO FIRE BURN SCAR IS CANCELLED 
FOR SAN BERNARDINO COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 3411 11695 3412 11686 3416 11683 3420 11690
      3419 11695 3416 11697

$$

12

Area Forecast Discussion
National Weather Service San Diego CA
138 PM PDT Sun Jul 30 2023

.SYNOPSIS...
A strong area of high pressure over the southern Rockies that has
been contributing to our warm weather over the past few weeks will
continue to influence our weather this week. Moist monsoonal flow
around this system will lead to a chance of showers and storms for
much of the area through Tuesday as temperatures dip near average.
Most areas will feel the humidity with highest chance of storms
for the mountains and deserts. We will dry out Wednesday into the
weekend with a slow warming trend inland, while the coastal areas
maintain closer to average readings and a continuous shallow marine
layer presence.

&&

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

.SHORT TERM...(Today through Tuesday)...
A broad area of high clouds will continue to push northward across
the region, keeping a looser lid on temperatures while humidity
increases this afternoon. Monsoon flow from the south and east has
triggered cumulus to build over the mountains, which may produce
a brief storm or two this afternoon. A short lull in the action
will occur this evening with dry and warm summer weather.

Hi-res models continue to show an easterly wave impacting the
area sometime later tonight into early Monday morning, pushing
showers and thunderstorms across the southern two thirds of the
region, highest chance over San Diego County. This can be a bit
hard to pinpoint in the models, but be prepared for storm activity
during this time, even those in the valley and coastal areas. The
earliest this may enter the area would be sometime right after
midnight, but most likely 3-5AM pushing westward by later in the
morning per latest HRRR and WRF guidance. Plentiful moisture will
be in place (ensemble PWAT values at PS/Thermal peak around 1.6
inches) with southeasterly flow aloft, will allow for showers and
storms to form over the mountains Monday afternoon with greater
coverage than today. HREF and other hi-res model guidance points
to cells developing by the afternoon hours, which will produce
brief heavy downpours, gusty outflow winds and localized flash
flooding.

We will have to watch our friends in Arizona and northern Mexico
to see if we will see another easterly wave come our way Monday
night into Tuesday morning, which would yet again bring showers
and storms all the way to the coast. Upper level winds shift a
bit more south on Tuesday, but instability and moisture will still
be in place, so a chance for storms is possible for many areas
again by Tuesday afternoon, highest chance for the mountains.

&&

.LONG TERM...(Wednesday through Next Weekend)...
The large area of high pressure over the Southern Rockies will
flatten a bit and move over Texas, leading to flow aloft turning
southwesterly and drying out by Wednesday. This will bring in
greater onshore flow across SoCal Wednesday into Thursday, leading
to the coolest time period for those west of the mountains. NBM
puts highs (dare we say it), up to 5 degrees below average from
the mountains to the coast. The ridge of high pressure is expected
to expand westward a bit closer to us by Friday into next
weekend, where temperatures are expected to yet again, go slightly
above average for most areas.

&&

.AVIATION...
302015Z...Coast...SCT-BKN clouds at/above 15,000 FT MSL continuing
through this evening/ Patchy low clouds potentially redeveloping
this evening generally after 09Z, though CIGS may be intermittent at
the coastal TAF sites most of the might with a 30-50% chance of
occurrence through 15Z Monday. There is a 25-35% chance of showers
and thunderstorms for the coastal areas after 06Z Mon, best chances
Monday morning into the afternoon.

Elsewhere...There is a 20-40% chance of ISO TSRA over the mountains
this afternoon 21-02Z with bases near 10,000 ft MSL and tops to 35-
40 kft MSL. More widespread -SHRA/TSRA possible (15-40% chance) for
all areas after 06Z Monday. Gusty winds and reduced vis VCTY TSRA.
Otherwise FEW-SCT clouds at/above 15,000 ft MSL through Monday
afternoon.

&&

.MARINE...
There is a slight chance of thunderstorms over the coastal waters at
times tonight through Tuesday, with the highest chances (25-35%)
Monday morning and afternoon. Lower chances (10-20%) on Sunday night
and Tuesday.

&&

.BEACHES...
There is a slight chance thunderstorms will impact the beaches at
times tonight through Tuesday. Beachgoers should be alert to the
presence of lightning and seek shelter if any occurs. The highest
chances are Monday morning and afternoon - around 25-40% for San
Diego County and 15-25% in Orange County. Lower chances (10-20%)
Sunday night and Tuesday, with the higher potential remaining over
San Diego County.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT this evening for Riverside County
     Mountains-San Bernardino County Mountains-San Bernardino
     and Riverside County Valleys-The Inland Empire-San Diego
     County Mountains.

PZ...None.

&&

PUBLIC...APR
AVIATION/MARINE...Adams