Multiple rounds of monsoonal thunderstorms occurred on August 7th through the 9th. A few severe thunderstorms produced high winds, while many others produced very heavy rain and flash flooding.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
Multiple rounds of monsoonal thunderstorms occurred on August 7th through the 9th. A few severe thunderstorms produced high winds, while many others produced very heavy rain and flash flooding.
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 Aug 7, 12:32 PM PST, 4 hours 26 minutes earlier.
Area Forecast Discussion
National Weather Service San Diego CA
132 PM PDT Sun Aug 7 2022
.SYNOPSIS...
Sunny today and hot inland this afternoon, where temperatures across
the Inland Empire and deserts will exceed 100 degrees. Monsoonal
moisture is moving back into Southern California from the southeast,
and isolated showers or thunderstorms could develop over the mountains
this afternoon. Increasing moisture and clouds Monday and Tuesday
will temper the heat, but bring better chances for more
widespread showers and thunderstorms. Some drying is possible
after Tuesday, but small chances for mountain and desert
thunderstorms will continue through the end of the week. The
shallow marine layer will persist along the coast, but nocturnal
low cloud formation will be limited.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
This afternoon, cumulus buildups forming over the mountains but
only very weak echoes are showing up on radar. A capping inversion
is making it difficult for deep convection to develop and higher
clouds moving across the region from the southeast are inhibiting
the surface heating. The potential remains and we could see at
least a few tstms over the mtns this afternoon before we lose the
daytime heating. Temperatures west of the mtns are generally
higher than at this time yesterday, especially in the Inland
Empire where temperatures as as much as 9 degrees higher than at
this time yesterday. Several locations in the IE are already
reporting triple-digit temps.
From previous discussion...
The drying brought about by low pressure centered off the
northern CA Coast, will slowly give way to increasing moisture
from the east as several weak easterly waves round the giant
subtropical high straddling the Rockies and Great Plains. Chances
will be better for more widespread shower/tstm activity Monday
and Tuesday, along with more high clouds. Precipitable water
values will once again reach the 1.5-2.0 inch range across SoCal
by Tuesday, so given sufficient daytime heating, intense downpours
could accompany any strong thunderstorm development. Increasingly
moist, easterly flow aloft could transport a lot of high clouds
our way, limiting daytime heating, but pushing a few
shwrs/tstms west of the mountains as well. With sufficient
afternoon heating, strong thunderstorm development could result in
intense downpours and local flash flooding. At this time, Mon and
Tue look similar in terms of the potential for convective
development extending from the mtns westward into the valleys and
possibly coastal areas.
After Tuesday, the steering winds shift to become more southerly.
This could cause a bit of drying, but the synoptic pattern really
changes little, keeping us caught between low pressure off the
PacNW Coast, and the giant subtropical high centered over the
Rockies. As we teeter between these two systems, weak easterly
waves can complicate the balance and increase or decrease
shower/t-storm potential as winds aloft shift the moisture
balance. This keeps slight chances for showers/tstms in the latter
periods of the forecast intact over the mountains and deserts,
where moisture will be more plentiful.
After the heat today, daytime temperatures are expected to be close
to seasonal averages, while overnight lows trend warmer, due to
higher humidity and a warmer sea surface. Even though nearshore
water temperature measurements have lowered, buoy data shows that
sfc water over a large portion of the CA Bight has warmed into
the lower 70s Fahrenheit.
The warm water and active monsoon pattern will serve to limit the
presence of marine layer clouds through this week and we could see
significant day-to-day variations in the extent of low clouds in
the coastal areas.
&&
.AVIATION...
072015Z...Coast/Valleys...SCT-BKN high clouds will continue across
the region today into tonight with cigs AOA 15K ft MSL and
unrestricted vis. Confidence is moderate on any widespread low cloud
coverage tonight for coastal TAF sites, best chance in SD County. If
any low clouds form, they will occur from 10-16Z Mon, though most
likely FEW-SCT conditions will prevail with bases 1000-1500 ft MSL.
Mountains/Deserts...Unrestricted vis with SCT-BKN clouds above 15K
ft MSL will continue through the afternoon, with a bit clear
conditions by nightfall. There is a slight chance of TSRA over the
mountains until 01Z this evening. Cloud bases 8000-10000 ft MSL and
tops near 25000 ft MSL, along with strong up/downdrafts and erratic
winds near any TSRA.
&&
.MARINE...
Northwest winds with gusts around 20 knots will occur over portions
of the outer coastal waters between 30 and 60 NM offshore this
afternoon and early evening. There is also a small risk of
thunderstorms Monday through most of next week over the coastal
waters, with best chances of storms on Monday and Tuesday.
Otherwise, no hazardous marine weather is expected through Friday.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 7 PM PDT this evening for San Bernardino and
Riverside County Valleys-The Inland Empire-San Gorgonio
Pass Near Banning-Santa Ana Mountains and Foothills.
PZ...NONE.
&&
PUBLIC...PG
AVIATION/MARINE...APRPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN DIEGO CA
544 PM PDT SUN AUG 7 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0458 PM DEBRIS FLOW 11 E ANZA 33.58N 116.48W
08/07/2022 RIVERSIDE CA LAW ENFORCEMENT
CHP REPORT OF ROCKS IN THE EASTBOUND LANDS
OF HIGHWAY 74 NEAR PINYON PINES. HEAVY RAIN
ONGOING IN THE AREA AT THE TIME.
&&
SSThe San Diego radar (KNKX), 87 km away, was scanning. The volume nearest the first event began at 01:00 UTC.
5 heavy rain, 2 debris flow, 2 flash flood, 1 flood, 1 thunderstorm wind, 1 strong wind. Local standard time, as filed.
California Highway Patrol reports rocks in the eastbound lanes of Highway 74 near Pinyon Pines. Heavy rain ongoing in the area at the time.
California Highway Patrol reports mud and water across both lanes of Highway 18. Radar estimates 0.25/hr-0.5/hr rain rates.
CHP report of van stuck in flood water on Rabbit Springs Rd in Lucerne Valley. Radar estimated around 1 inch of rain.
A 71 mph wind gust was measured from the Horse SDHGPA Mesonet Station.
More than 200 people were stranded at the Palm Springs Aerial Tramway as heavy rain in the San Jacinto Mountains and State Park caused impassible mudflows along the exit road from the valley station. Operations of Palm Springs said mud began flowing down east of the station onto the road. The flow appeared to be mostly mud, and not debris. Rainfall of 1.99 inches was measured at the Mt San Jacinto Peak RAWS site.
Yucaipa Ridge near Wilshire Peak at 9000 feet reported 0.79 inches of rainfall in 15 minutes, and 1.50 inches in 1 hour.
California Highway Patrol reports a downed oak tree, approximately 5 feet wide, fell across both lanes of traffic along Old Highway 80 and Deodar Tri.
Mesonet station LGMC1 Mt Laguna near 6000 feet reported heavy rainfall of 1.39 inches.
Mesonet station JULC1 Julian RAWS reported heavy rainfall of 0.85 inch.
Mesonet station LGMC1 Mt Laguna reported rainfall of 1.39 inch near 6000 feet.
CHP Incident report of a large rock slide and portions of S2 extending into San Diego County washed out.
Mesonet station MSJC1 Mt San Jacinto reported heavy rainfall of 1.99 inches. Flooding was reported at the Long Valley Ranger Station, and tram operations were halted.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2022Every state in 2022This day in weather historyWarnings in California, August 2022
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: 1047160, 1047161, 1040825, 1040834, 1040822, 1040830, 1047156, 1040831, 1040832, 1047162, 1040824, 1040833.