Flash Flooding in California, July 11, 1999

Thunderstorms redeveloped along the mountains to the south of Forest Falls/Mill Canyon and moved down the south slopes across Oak Glen, Cherry Valley, Beaumont, and Banning. Radar rainfall estimates in the Oak Glen area were near 4 inches. Flash flooding there caused heavy damage to a mile of water lines, ponds, roads, culverts, and a Prison Camp. As the flood waters moved south down the Little San Gorgonio Creek and the San Gorgonio River, the thunderstorms also moved south, dropping additional heavy rain. Beaumont reported 1.36 inches of rain in less than an hour. Power lines and poles were knocked down and mud, tree limbs, rocks, and other debris were washed onto local streets and major roadways in Cherry Valley, Beaumont, and Banning. Several accidents along Interstate 10 in the Banning Pass were also attributed to the poor visibility and cars hydroplaning in the heavy rain. Minor flooding was reported in southeast Yucaipa and Calimesa along Wildwood Creek.