The month began with a ridge of high pressure over the Great Basin and moderate easterly flow in the mid and upper levels. This allowed monsoon moisture to surge into the southern half of California August 1st-3rd. Severe storms occurred in the Inland Empire and San Diego County Valleys on the 1st. Storms focused more on the mountains and deserts on the 2nd and 3rd, with reduced intensity overall.

Lightning in RIVERSIDE, CALIFORNIA
From 03-AUG-17 02:45:00 to 03-AUG-17 03:45:00 (PST-8)
Location: DESERT HOT SPGS
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Utility Company

Lightning strikes produced power outages in Desert Hot Springs.

Flash Flood in RIVERSIDE, CALIFORNIA
From 03-AUG-17 02:30:00 to 03-AUG-17 04:30:00 (PST-8)
Location: PALM SPGS
Flood cause: Heavy Rain
Property damage: 125.00K
Crop damage: 0.00K
Reported by: Broadcast Media

An intense thunderstorm produced widespread street flooding in Palm Springs. Flood water inundated Palm Spring High School with 1-1.5 inches of water, damaging 10 classrooms.

Flash Flood in RIVERSIDE, CALIFORNIA
From 01-AUG-17 15:00:00 to 01-AUG-17 16:00:00 (PST-8)
Location: DURANT
Flood cause: Heavy Rain
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A mud and debris flow from a recent fire flowed over Grand Ave. and Plumas St., both roads were closed.

Thunderstorm Wind in SAN DIEGO, CALIFORNIA
From 01-AUG-17 13:00:00 to 01-AUG-17 13:30:00 (PST-8)
Location: ALPINE
Magnitude: 56.00 EG
Property damage: 15.00K
Reported by: Law Enforcement

Severe downburst winds knocked down branches that blocked roadways in Alpine and Harbison Canyon. A spotter estimated winds at 65 mph plus.

Thunderstorm Wind in RIVERSIDE, CALIFORNIA
From 01-AUG-17 15:15:00 to 01-AUG-17 15:45:00 (PST-8)
Location: EL CERRITO
Magnitude: 48.00 EG
Property damage: 25.00K
Reported by: Law Enforcement

Power lines downed by strong outflow winds.

Flash Flood in SAN DIEGO, CALIFORNIA
From 03-AUG-17 12:30:00 to 03-AUG-17 14:00:00 (PST-8)
Location: DESERT LODGE
Flood cause: Heavy Rain
Property damage: 0.50K
Crop damage: 0.00K
Reported by: Law Enforcement

Heavy runoff through a normally dry wash flowed over Highway 78 two miles east of Yaqui Pass, forcing a closure of the highway.

Flash Flood in RIVERSIDE, CALIFORNIA
From 01-AUG-17 15:00:00 to 01-AUG-17 16:00:00 (PST-8)
Location: ALBERHILL
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Broadcast Media

An intense thunderstorm produced intense street flooding in southern Corona. Flow pushed debris, branches, and trash cans down local streets. The flow along Colt Dr. was strong enough to damage and shift parked cars.

Thunderstorm Wind in SAN BERNARDINO, CALIFORNIA
From 01-AUG-17 13:15:00 to 01-AUG-17 13:35:00 (PST-8)
Location: SAN BERNARDINO
Magnitude: 52.00 EG
Property damage: 35.00K
Reported by: Broadcast Media

Severe winds downed a large tree (diameter > 2 ft) on a home in San Bernardino. A brief funnel cloud was also reported.

Thunderstorm Wind in RIVERSIDE, CALIFORNIA
From 01-AUG-17 14:15:00 to 01-AUG-17 15:30:00 (PST-8)
Location: PERRIS
Magnitude: 56.00 EG
Property damage: 25.00K
Reported by: Law Enforcement

Downburst winds toppled power lines and downed multiple large trees blocking several roadways in Perris.

Flash Flood in RIVERSIDE, CALIFORNIA
From 01-AUG-17 12:20:00 to 01-AUG-17 14:20:00 (PST-8)
Location: AGUANGA
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Law Enforcement

High waters sent flows over the roadway near the intersection of State Routes 79 and 371. Vehicles were trapped in rocks and debris and the roadway was closed by CHP at 1320PST.

Flood in SAN BERNARDINO, CALIFORNIA
From 03-AUG-17 16:45:00 to 03-AUG-17 17:45:00 (PST-8)
Location: WRIGHTWOOD
Flood cause: Heavy Rain
Property damage: 0.50K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported a debris flow from Sheep Creek Wash flowing over Lone Pine Canyon Rd.

Flood in SAN BERNARDINO, CALIFORNIA
From 03-AUG-17 13:30:00 to 03-AUG-17 14:30:00 (PST-8)
Location: RIMROCK
Flood cause: Heavy Rain
Property damage: 0.50K
Crop damage: 0.00K
Reported by: Social Media

Video via social media of 4-6 inches of water flowing over the road near the intersection of Pipes Canyon Rd. and Gamma Gulch Rd.

Heavy Rain in SAN DIEGO, CALIFORNIA
From 01-AUG-17 12:00:00 to 01-AUG-17 14:00:00 (PST-8)
Location: ALPINE
Reported by: County Official

A thunderstorm produced heavy rain with subsequent runoff that raised El Capitan Reservoir, a reservoir with a capacity of 112,800 acre feet, by 3 inches overnight.

Lightning in RIVERSIDE, CALIFORNIA
From 03-AUG-17 02:00:00 to 03-AUG-17 03:00:00 (PST-8)
Location: WARNER SPGS
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Utility Company

Lightning strikes produced power outages in Palm Springs.

Thunderstorm Wind in RIVERSIDE, CALIFORNIA
From 01-AUG-17 14:00:00 to 01-AUG-17 14:30:00 (PST-8)
Location: TEMECULA
Magnitude: 52.00 EG
Property damage: 50.00K
Reported by: Law Enforcement

A severe downburst struck Temecula and Murrieta, winds overturned a big rig, downed trees, and damaged traffic signals.