Severe thunderstorm causes considerable flooding and damage across eastern Idaho

IDAHO FALLS — After a severe thunderstorm and a spectacular lightning show on Thursday night, many eastern Idahoans are mopping up their basements and drying out their cars following intense, heavy rainfall and hail in some areas.

Many areas in eastern Idaho were under a severe thunderstorm warning for much of Thursday and part of Friday, with parts of those areas also being under a flash flood watch.

According to the National Weather Service, most of eastern Idaho will remain under a flash flood watch until midnight on Friday.

Many people reported damage to the National Weather Service on Thursday night, including hail up to the size of golf balls that damaged homes, cars, and camping trailers; basement floods; flooding car engines; and heavy rain that flooded and blocked roads.

Tim Axford, the Warning Coordination Meteorologist for the National Weather Service in Pocatello, says the storm spanned a wide area of eastern Idaho, but much of the damage was confined to specific parts north of the American Falls Reservoir and through the Blackfoot area.

“(Thursday) afternoon, we saw less sunshine and the area kind of destabilized and created a lot more thunderstorms in the area, especially the I-86 and I-15 corridor. It really set off a really profound lightning show that many took in last night and were able to view lightning from afar for some folks, and lightning right over a lot of folks as well,” says Axford. “Those storms generally tracked from American Falls through Blackfoot, Idaho Falls, up to Rexburg. And that’s where we say the corridor of the strongest, biggest hail, and heaviest rain as well. That’s where we saw most of the damage, and most of the storm reports with hail and heavy rain.”

The largest hailstones, Axford says, were in the Bingham County area, and they got considerably smaller before they struck Idaho Falls and Rexburg.

“There were some reports of around an inch, or a quarter-sized hail, but for the most part, Idaho Falls saw a lot of localized street flooding with that heavy rain,” says Axford.

Lots of social media photos and videos showed rain pouring into homes through overwhelmed window wells, flooding neighborhood streets, and blocking underpass roads. See videos of this in the player above.

“We are seeing rainfall rates (at) half an inch to an inch in an hour, some spots even more, and even higher than that,” says Axford. “That much rain is enough to inundate, especially urban environments where things like street drains can get clogged with debris and things like that.”

Axford says several buildings in Rexburg experienced flooding, including campus buildings at Brigham Young University-Idaho.

Preparing yourself, your family, and your home for storms is important, says Axford, who recommends memorizing some key phrases for situations like Thursday’s weather.

“When it comes to thunderstorms and safety, we have two rhymes that we always say. One is ‘When thunder roars, go indoors,'” says Axford. “If you’re close enough to hear thunder, you’re close enough to get struck by lightning. We want people to really heed the advice to stay inside during thunderstorms. Similarly, we have another rhyme that we say, ‘Turn around, don’t drown.’ If you come across any flooded roadways, especially in the urban environments that we see where underpasses come into play, we don’t want people risking it to try and make it through there.”

As for the rest of the weekend, Axford says the weather is likely to be similar to Thursday night until Saturday.

“After (Friday), we’ll still see some showers and potential thunderstorms around through (Saturday), but for the most part, we’re going to be on this drying trend through the rest of the weekend,” says Axford. “Especially Sunday should be really nice, and a clear day.”