Flash Flood Warning 7, NWS San Diego, CA

180 
WGUS76 KSGX 182157
FFSSGX

Flash Flood Statement
National Weather Service San Diego CA
257 PM PDT Fri Jul 18 2025

CAC071-182300-
/O.CON.KSGX.FF.W.0007.000000T0000Z-250718T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-
257 PM PDT Fri Jul 18 2025

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 4 PM PDT THIS 
AFTERNOON FOR SAN BERNARDINO COUNTY...

At 257 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 1 and 1.5 inches of rain have 
fallen. The expected rainfall rate is 0.25 to 0.5 inches in 1 hour. 
Additional rainfall amounts up to 0.25 inches are possible in the 
warned area. Flash flooding is ongoing or expected to begin shortly.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include...
  Hesperia, Lake Arrowhead, Hwy 173 Between Lake Arrowhead And 
  Hesperia, Skyforest, Cedar Glen and Twin Peaks.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

&&

LAT...LON 3425 11710 3424 11717 3424 11724 3438 11728
      3438 11713

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL RATE...0.25-0.5 INCHES IN 1 HOUR

$$

Munyan

Area Forecast Discussion
National Weather Service San Diego CA
916 AM PDT Fri Jul 18 2025

.SYNOPSIS...
Monsoonal moisture will continue to bring chances for showers and
thunderstorms across the region through Saturday afternoon. The
best chances for thunderstorms with periods of locally moderate
to heavy rainfall will be this afternoon in the mountains and high
deserts. Dry conditions return on Sunday and continue through the
middle of next week. Daytime high temperatures are expected to
remain near or a little below seasonal averages through the middle
of next week.

&&

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

.Morning Update...

Mid level clouds continue to push in from the northwest. Some of
these are associated with light showers from stronger
thunderstorms earlier this morning. Some areas from San Clemente
into parts of the eastern/southern Inland Empire received near one
quarter of an inch of rainfall. Meanwhile, the marine layer is
maintaining its grip across western San Diego County, shrouding
the coastal slopes in fog with a "no sky July" morning across the
San Diego metro area. These low clouds will shrink back to the
coast later this morning.

An area of low pressure will move northward today, helping to pull
in more monsoonal moisture across the area. Chances for
thunderstorms are in the forecast for mountainous regions and
parts of the Coachella Valley and high desert. Hi-res models show
convection forming after 12 noon as NBM chances for thunder are
25-40 percent. Anyone who sees these storms may also see small
hail and gusty winds. The low will weaken and move northward by
Saturday, keeping chances of storms limited to the Riverside/SBD
Co mountain areas.

.Previous Discussion...

For this afternoon...chances for periods of locally heavy
rainfall increase significantly for the mtns and high deserts as
daytime heating becomes a factor, providing added forcing for deep
convection. High temperatures today will continue to be near or a
little below seasonal averages

Chances for showers/tstms decrease tonight as the upper low moves
north and we lose what little forcing there is. Moisture and
instability persist into Saturday afternoon so that when daytime
heating returns, showers/tstms can once again develop over the
mtns and deserts. Less vertical mixing above the marine layer will
allow for the return of more extensive low clouds with patchy fog
tonight into Sat morning.

By Sunday, we lose most of the monsoonal moisture as we begin to
see drier southwest flow aloft which will essentially end the
threat of showers/tstms as we return to a more stable atmosphere.

For Monday through the middle of next week...a low/trough will
dominate the pattern over the west coast, displacing the sub-
tropical high eastward over the Gulf Coast states. This will bring
us near-seasonal temperatures with a persistent marine layer for
low clouds and fog in the coastal areas and valleys each night and
morning.

&&

.AVIATION...
181530Z....Coast/Valleys...ISO-SCT SHRA based at around 10000
feet through 18Z, generally confined to Orange and Riverside
counties. Coastal low clouds in San Diego County based at
1500-1800 feet and tops to 2000 feet will gradually clear by 17Z.
TSRA 20% chance in inland valleys near the mountains 19-01Z. Low
clouds return to coastal areas mainly after 05Z, with bases around
1500 feet MSL. Scatter out Saturday by 17Z.

Mountains/Deserts...SCT-BKN clouds 10000-15000 feet. ISO-SCT SHRA
and TSRA over the mountains and high desert 18-02Z, with CU/CB bases
7000-9000 feet MSL, tops to 40000 feet. Erratic wind gusts, strong
up/downdrafts, and VIS restrictions possible with any storm that
develops. Mostly clear after 03Z.

&&

.MARINE...
No hazardous marine weather expected through Tuesday.

&&

.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...APR
AVIATION/MARINE...MM