Probable ‘supercell’ brings heavy rain to Chico, flooding streets and Cal State campus

A heavy thunderstorm Tuesday night inundated the Northern California city of Chico, flooding streets, homes, businesses and buildings at Cal State Chico.

Jeff Ranieri, chief meteorologist at NBC Bay Area, tweeted that from 4 p.m. to 8 p.m. a long-lasting thunderstorm, probably a “supercell,” produced 3 to 5 inches of rain.

Roads around a Chico hospital were completely flooded and barely passable on Tuesday night. The Chico Police Department received several hundred calls for service.

Jeramie Struthers, a watch commander with the Chico Police Department, said the amount of flooding was unprecedented, and in his 17 years living in the area he’d never seen a storm like it.

The city’s drainage system was overwhelmed, forcing manhole covers to pop out and water to flow back out of the system, he said.

The storm was somewhat of a surprise, Struthers said.

“There was a weather forecast alert earlier, in the 5 o’clock range, because there was a possible tornado event, and that was the only thing I heard — there was no, like, ‘Watch out, here comes Noah’s ark,’” he said.

Chico Fire Chief Steve Standridge said his department spent the evening helping stranded motorists and, in one case, helped residents leave their home from the second story using ladders.

“It wasn’t supposed to be that bad,” Standridge said. “We had a tornado warning about 4 p.m. to 5 p.m., and then after that, probably around 7 o’clock, it started raining hard, and it just hit for about a two-hour period.”

Because floodwaters weren’t particularly swift, some residents spent time outside in kayaks and pool floaties; one opted for a large inflatable duck.

At Cal State Chico, some campus buildings experienced flooding, and a full assessment and cleanup was underway, the university said on Twitter on Tuesday night. It wasn’t yet known what impact the flooding would have on classes or the campus Wednesday.

The rain lasted about five hours, stopping about 9:30 p.m. Overnight, the main concern was water draining out of the city west into small streams and culverts, potentially flooding nearby rural areas.

“A flash-flood warning is somewhat unusual — they’re not issued very often,” said Karl Swanberg, a forecaster with the National Weather Service in Sacramento. “This was a bad one, and it was a very slow-moving thunderstorm complex, and Chico just happened to be strongly affected by it.”