Monsoonal thunderstorms occurred on July 25 in the Riverside County Mountains and San Diego County Mountains. 75 was reported in Riverside County, and a lightning strike ignited a small wildfire in San Diego County.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS SGX wrote it up.
Monsoonal thunderstorms occurred on July 25 in the Riverside County Mountains and San Diego County Mountains. Locally heavy rainfall of 0.50-0.75 was reported in Riverside County, and a lightning strike ignited a small wildfire in San Diego County.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS San Diego, CA wrote its last area forecast discussion before the first event at Jul 25, 1:10 PM PST, 50 minutes earlier.
Area Forecast Discussion
National Weather Service San Diego CA
210 PM PDT Tue Jul 25 2023
.SYNOPSIS...
Isolated thunderstorms over the mountains and deserts this afternoon
will end this evening. Hot weather will continue this week with
strong high pressure over the Southwest. Low clouds and locally
dense fog will spread into coastal areas each night and morning.
Early next week it will not be quite as hot, and an increase in
monsoon moisture will bring chances for mountain and desert
thunderstorms.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
Today was another exceptionally hot day in the valleys, mountains
and deserts, and a much cooler and generally cloudy day at the San
Diego County beaches. 1 PM temperatures ranged from 115 at Palm
Springs (the record is 117), 104 at Victorville and San Bernardino,
99 at Ramona, 87 at Fullerton, 68 at Mission Beach and 67 at Newport
Beach.
The heat dome associated with the strong 600 dm high over New Mexico
will hold on through the end of the weeks, then slowly drift east
over the weekend. Therefore, the Heat Advisories that were in effect
for the valleys and mountains through Wednesday have been extended
through 8 PM Friday, as were the Heat Warnings in the Lower Deserts.
Moisture advection in the southeast flow aloft today combined with
the heating of the day triggered short-lived isolated showers and
thunderstorms over the mountains this afternoon. The storms will end
with the setting sun. The Precipitable Water over the mountains
maxed out at 1.15", then falls below 1 inch Wednesday and Thursday
for lesser chances of convection Wednesday afternoon.
The heat continues through Friday, then over the weekend and into
early next week the 500 mb heights lower as the upper high drifts
east toward the southern Plains. Temperatures here is SoCal will not
be quite as hot early next week. Additionally, the long range
ensembles show a surge of monsoonal moisture into SoCal for chances
of thunderstorms over the mountains and deserts.
&&
.AVIATION...
252025Z...Coast/western valleys...Low clouds with bases 500-800 FT
MSL are persisting at the immediate coast this afternoon, with
clouds likely continuing through much of the day. Widespread low
clouds will move back inland after 03z Wed, with bases 600-900 FT
MSL. Expect reduced vis of 2-4 SM and local reductions below 1 SM,
mainly where low clouds and higher coastal terrain intersect.
Otherwise, SCT-BKN AOA 12,000 FT MSL through tonight.
Mountains/deserts...SCT-BKN AOA 12,000 FT MSL through tonight. Iso
TSRA possible through 01z Wed with CB 10,000 FT MSL and tops to
30,000 FT MSL. Gusty and erratic winds are possible vcty TSRA.
&&
.MARINE...
Patchy dense fog with visibility less than 1 SM will be possible
overnight into Wednesday morning. Otherwise, no hazardous marine
conditions are expected through Sunday.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT Friday for Riverside County
Mountains-San Bernardino County Mountains-San Bernardino
and Riverside County Valleys-The Inland Empire-San Diego
County Mountains-San Diego County Valleys.
Excessive Heat Warning until 8 PM PDT Friday for Coachella
Valley-San Diego County Deserts-San Gorgonio Pass Near
Banning.
PZ...None.
&&
PUBLIC...Moede
AVIATION/MARINE...EAThe national radar mosaic for the moment the first event began.
1 heavy rain, 1 wildfire. Local standard time, as filed.
Monsoonal thunderstorms produced heavy rainfall across the Riverside County Mountains on July 25. Mountain Center CWOP reported 0.51 inch of rain in 30 minutes, and the Anza SE gauge reported 0.62 inch in one hour.
Small fire detected on camera from an apparent lightning strike near 5364 feet, around 9 miles west-southwest of Borrego Springs.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2023Every state in 2023This day in weather historyWarnings in California, July 2023
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1124509, 1124510.