Strong high pressure aloft over the southwest U.S. produced a monsoonal flow over much of California, resulting in periods of showers and thunderstorms, mainly in the mountains and deserts. An upper atmospheric disturbance produced widespread showers and a few thunderstorms with moderate rainfall over northern portions of the area overnight on the 30th into the early morning of the 31st. A few of the storms were quite heavy to locally severe during the afternoons of the 30th and 31st. Many of the strongest storms occurred over rural mountain and desert areas where verification was difficult. Flash Flooding was reported in the Victorville area of the northern deserts on the 30th, along with some wind damage. The nocturnal event on the night of the 30th produced several hundred lightning cloud to ground lightning strikes.

Flood in SAN DIEGO, CALIFORNIA
From 30-JUL-11 15:40:00 to 30-JUL-11 17:20:00 (PST-8)
Location: BANNER
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Local flooding at mile marker 15 of county road S-2, north of Scissors Crossing. Heavy rain from a thunderstorm moving north along S-2 caused low parts of the road to be covered with a few inches of running water.

Flood in SAN BERNARDINO, CALIFORNIA
From 31-JUL-11 10:00:00 to 31-JUL-11 11:30:00 (PST-8)
Location: THORN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy rain from several hours caused street flooding on Palmdale Road at Del Gado.
1 inch rain in 12 hours.

High Wind in APPLE AND LUCERNE VALLEYS, CALIFORNIA
From 30-JUL-11 12:20:00 to 30-JUL-11 14:00:00 (PST-8)
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter estimated a 60 mph wind gust from a thunderstorm in the area. Powerlines also reported down on 7th and D streets due to wind knocking down trees onto lines.

Flash Flood in SAN BERNARDINO, CALIFORNIA
From 31-JUL-11 15:15:00 to 31-JUL-11 17:00:00 (PST-8)
Location: WRIGHTWOOD
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter RIV116 reported numerous debris flows and arroyo flooding along Lone Pine Canyon Road near Wrightwood due to heavy rain from a thunderstorm.

Heavy Rain in SAN BERNARDINO, CALIFORNIA
From 30-JUL-11 12:00:00 to 30-JUL-11 14:00:00 (PST-8)
Location: APPLE VLY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A member of the public reported 0.76 inches of rain falling in a period of 45 minutes during a thunderstorm on the 30th. She also reported pea sized hail and substantial lightning.

Hail in SAN DIEGO, CALIFORNIA
From 31-JUL-11 11:00:00 to 31-JUL-11 13:00:00 (PST-8)
Location: BOULEVARD
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

An employee of the Golden Acorn Casino along I-8 near Boulevard estimated penny-sized hail around 1200 PST.

Thunderstorm Wind in SAN DIEGO, CALIFORNIA
From 31-JUL-11 15:00:00 to 31-JUL-11 16:00:00 (PST-8)
Location: OCOTILLO WELLS
Magnitude: 50.00 EG
Property damage: 23.00K
Crop damage: 0.00K
Reported by: Park/Forest Service

Anza-Borrego State Park rangers reported three power poles down due to thudnerstorm wind gusts.

Flood in SAN BERNARDINO, CALIFORNIA
From 30-JUL-11 13:30:00 to 30-JUL-11 14:41:00 (PST-8)
Location: THORN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Parts of Ridgecrest Road flooded near railroad tracks. Many streets in Spring Valley have flowing water. Street flooding between Balsom and Mariposa. Outside lane flooding between Cottonwood and Nisqualli.

Flood in SAN BERNARDINO, CALIFORNIA
From 30-JUL-11 13:30:00 to 30-JUL-11 14:41:00 (PST-8)
Location: THORN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Parts of Ridgecrest Road flooded near railroad tracks. Many streets in Spring Valley have flowing water. Street flooding between Balsom and Mariposa. Outside lane flooding between Cottonwood and Nisqualli.