Tropical Storm Hilary brought abundant moisture along with strong winds to southern California on the 20th. In fact, Tropical Storm Warnings were issued for the first time in history along the southern California coast. On the 19th, a trough near the southern California coast promoted deep southerly flow that allowed deeper moisture to advect into the Southwest ahead of Hilary. Combined with jet dynamics, showers and thunderstorms developed during the early morning hours on the 19th, leading to an isolated instance of flash flooding in southeast California. Going into the 20th, very anomalous moisture accompanied Hilary with PWATs across southeast California climbing upwards of 2-2.5 and IVT values in excess of 15 normalized standard deviations from average. Thus, flash flooding was the primary impact across southern California with a very rare high risk of excessive rainfall being issued by WPC for part of the area. Rainfall totals across southeast California were as high as 2-3, while most areas across Imperial County and eastern Riverside County generally measured around 1.50 or less. However, much heavier rainfall amounts were observed closer to the southern California coast. In addition to flash flooding impacts, several instances of damaging winds occurred as strong low level winds upwards of 50-60 knots at 850 mb and 925 mb mixed to the surface in some cases. Several communities around the Salton Sea were under a voluntary evacuation order as a precaution for any potential impacts stemming from flash flooding and strong winds. Multiple reports of flooding impacts and wind damage primarily across Imperial County resulted from this event. No injuries were reported.

Flash Flood in IMPERIAL, CALIFORNIA
From 20-AUG-23 12:28:00 to 20-AUG-23 14:28:00 (PST-8)
Location: POPE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Storm Chaser

Multiple unbridged areas along SR 111 between Niland and North Shore were impacted due to flash flooding. Flash flooding impacts spanned along this highway in Imperial and Riverside Counties. According to local media, there were at least 10 reports of vehicles that became stuck along the highway and needed assistance from Imperial County Fire Department. No injuries were reported.

Flash Flood in IMPERIAL, CALIFORNIA
From 20-AUG-23 11:53:00 to 20-AUG-23 13:53:00 (PST-8)
Location: HOLTVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

CHP reported flash flooding near Orchard Road and Edwards Road. No injuries were reported.

Flash Flood in IMPERIAL, CALIFORNIA
From 20-AUG-23 12:15:00 to 20-AUG-23 14:15:00 (PST-8)
Location: SALTON CITY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

A social media video showed that a low water crossing along Marina Drive in Salton City was impassable due to flooding. No injuries were reported.

High Wind in IMPERIAL VALLEY, CALIFORNIA
From 20-AUG-23 16:16:00 to 20-AUG-23 16:16:00 (PST-8)
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A large tree was blown down near El Centro Street and Haskell Road. No injuries were reported.

Flash Flood in IMPERIAL, CALIFORNIA
From 19-AUG-23 05:30:00 to 19-AUG-23 07:30:00 (PST-8)
Location: OCOTILLO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

According to Caltrans, Highway 98 near Ocotillo was closed due to flash flooding. No injuries were reported.

High Wind in IMPERIAL VALLEY, CALIFORNIA
From 20-AUG-23 14:23:00 to 20-AUG-23 14:23:00 (PST-8)
Magnitude: 50.00 EG
Property damage: 6.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Power poles were reported down near Evan Hewes Highway. No injuries were reported.

High Wind in IMPERIAL VALLEY, CALIFORNIA
From 20-AUG-23 14:53:00 to 20-AUG-23 14:53:00 (PST-8)
Magnitude: 57.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

A peak wind gust of 66 mph was measured at KIPL. However, the station stopped reporting during the event, so it's unknown if stronger gusts occurred later in the day.

High Wind in IMPERIAL VALLEY, CALIFORNIA
From 20-AUG-23 14:53:00 to 20-AUG-23 14:53:00 (PST-8)
Magnitude: 50.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Newspaper

A gas station canopy located on the corner of Adams Avenue and Imperial Avenue fell down due to strong winds. Additional reports throughout the Imperial Valley included downed trees, power poles, and light poles with the exact location of these occurrences unknown. No injuries were reported. Timing estimated based on peak wind gust at KIPL.

High Wind in IMPERIAL COUNTY SOUTHEAST, CALIFORNIA
From 20-AUG-23 12:19:00 to 20-AUG-23 12:19:00 (PST-8)
Magnitude: 50.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A couple of tractor trailers were blown over along I-8 near the Glamis Dunes. No injuries were reported.

High Wind in CHUCKWALLA VALLEY, CALIFORNIA
From 20-AUG-23 15:05:00 to 20-AUG-23 15:05:00 (PST-8)
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

A 58 mph gust was recorded at KBLH.

Flash Flood in IMPERIAL, CALIFORNIA
From 20-AUG-23 12:09:00 to 20-AUG-23 14:09:00 (PST-8)
Location: SALTON CITY
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flash flooding was reported in Salton City along Seaview Drive, which has a low water crossing through a wash. According to local media reports, a mother and her two children had to be rescued after their vehicle became stuck in a wash. No injuries were reported.