Forest Falls, California — A sudden thunderstorm unleashed heavy rain, hail, lightning and mudflows in the San Bernardino County mountains Thursday, sending mud and water into streets and pushing a Jeep off the road as officials warned of dangerous flash flooding across the region.
The storm quickly created messy and hazardous conditions in Forest Falls, where runoff carried debris into roadways. Crews moved in to clear the affected streets as the storm weakened, but the threat of additional flooding remained a concern across several nearby communities.
Thunderstorm Sends Mud and Water Into Streets
The pop-up thunderstorm developed rapidly over the San Bernardino County mountains, producing heavy rainfall, lightning and hail.
The intense rainfall generated enough runoff to send mud and water flowing into streets in Forest Falls. A Jeep was reportedly pushed off the road as the water and debris moved through the area.
Crews responded quickly to clear the mud and debris, helping reopen affected areas after the storm moved through. The National Weather Service issued a severe flash flood warning for the region, with the warning remaining in effect until 7:30 p.m.
More Than an Inch of Rain Falls
The storm followed earlier thunderstorms that had already produced substantial rainfall across parts of the area. According to the National Weather Service, between 0.75 and 1.25 inches of rain had fallen in locations affected by the storms.
That amount of rain can create dangerous runoff when it falls quickly, particularly in mountainous terrain where water can move rapidly downhill and collect in lower areas.
Meteorologists said the rain cell positioned over Yucaipa was beginning to weaken, but the flash flood warning remained active as forecasters continued watching conditions.
The combination of saturated ground, steep terrain and additional thunderstorms can make mountain communities particularly vulnerable to sudden flooding.
Multiple Communities Were Under Threat
The flash flood warning covered a broad portion of the San Bernardino County mountains and nearby communities. Areas identified as being at risk included Yucaipa, Forest Falls, Banning, Mentone, Mountain Home Village and western Mount San Gorgonio.
These areas can experience rapid changes during strong thunderstorms because rainfall falling at higher elevations can quickly move toward communities and roads at lower elevations.
Residents and drivers in affected areas were urged to remain alert for rapidly rising water and avoid roads covered by floodwater.
Flash Flooding Could Extend Into the Desert
The threat was not limited to the immediate area around Forest Falls.
Other locations forecast to potentially experience flash flooding included Twentynine Palms and Twentynine Palms Base, where additional thunderstorms could produce sudden heavy rainfall.
While the most intense rain cell over Yucaipa was weakening, weather conditions remained capable of producing additional downpours.
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That meant communities across the region could continue to see localized flooding even after the strongest portion of the storm moved away.
Mountain Terrain Can Make Flooding Dangerous
Thursday’s storm was another reminder of how quickly weather conditions can deteriorate across Southern California’s mountain communities.
A storm that develops over a relatively small area can drop a large amount of rain in a short period, sending runoff toward roads and neighborhoods with little warning.
Mudflows are especially dangerous because they can carry rocks, debris and other material along with fast-moving water. Roads can become blocked within minutes, while vehicles caught in moving water can be swept away.
The fact that a Jeep was pushed from the roadway illustrated the force of the runoff generated by the storm.
Although crews were able to clear the immediate debris, additional thunderstorms could still create new flooding concerns if heavy rain develops over the same terrain.
Did you experience the storm in Forest Falls, Yucaipa or another nearby community? Share what you saw in the comments and let us know how the heavy rain affected your area.
