Thunderstorm cells developed in the Anza Valley Thursday, triggering heavy downpours along Highway 74 that created hazardous driving conditions and throughout the southern half of the San Bernardino National Forest.
The instability began shortly after 2 p.m. Thursday in the mountains south of Idyllwild, as well as in the Beauty Mountain Wilderness at the boundary separating Riverside and San Diego counties, according to National Weather Service radar echoes.
There were reports of a lightning strike fire in the area of Highway 74 and Santa Rosa Truck Trail, just east of Anza, at 2:30 p.m. However, a 20-minute search of the area by Cal Fire aircraft, which steered clear of the intense cells, didn’t result in identification of anything resembling a brush fire.
Ground and air crews at the scene acknowledged the heavy rainfall likely knocked down any flames that sprang up.
Both Riverside County Fire Department and U.S. Forest Service personnel joined in the search.
Similar thunderstorm activity was reported northeast of Desert Hot Springs, approaching Twentynine Palms, and in the mountains around Big Bear, Thursday afternoon.
No traffic accidents on Highway 74 in Anza were reported during the downpours.
By 3:30 p.m., the cells appeared to be spreading east and west. One radar track indicated the Temecula Valley might get hammered.
The NWS has been warning for weeks that monsoonal moisture would eventually spread into the Inland Empire from the southeast, spawning thunderstorms, particularly at higher elevations, during peak midday heat.