Possible thundersnow — yes, you read that right — is forecast for Boise. What is it?

Mere hours after temperatures reached the high 30s, a big storm was headed for the Treasure Valley on Monday night.

The National Weather Service issued a special weather statement Monday afternoon forecasting possible “thundersnow” for the region. Yes, thundersnow.

“Snow showers and possible thundersnow with gusty winds and the potential for poor visibility tonight,” the statement says.

Thundersnow is when it thunders and snows at the same time, said Chuck Redman, a meteorologist at the National Weather Service’s Boise office. Though the weather service doesn’t track thundersnow, it’s uncommon.

Redman said he’s unsure thundersnow will happen, noting that it’s possible, but there’s “not a great risk.” Just as a thunderstorm typically leads to heavier rainfall, thundersnow could mean bursts of heavier snowfall, he said. Less than half an inch of snow was predicted for the Boise area through 11 a.m. Tuesday.

“Heavier snow showers possibly, reduced visibility, maybe gusty winds with it as well,” Redman said by phone. “That’s typically what you can see with a thundersnow shower as it moves across.”

The forecast was issued just after 2 p.m. and includes the cities of Nampa, Caldwell, Boise, Mountain Home, Ontario, and Nyssa.

The weather service warned of wind gusts up to 40 mph and “strongly urge(s) caution” if traveling in the Treasure Valley between 8 p.m. and 4 a.m.

The lower Treasure Valley, meaning Nampa, Caldwell and Ontario, faced a greater threat from about 8 p.m. to 2 or 3 a.m., according to the weather service. The upper Treasure Valley, meaning Boise and Mountain Home, was likely to face the most-challenging conditions from about 10 p.m. to about 4 a.m.

“There will be brief periods of near-whiteout conditions in the stronger showers or any thunderstorms that form,” according to the weather service, “but most folks won’t experience much worse than around 1/2 visibility with brief heavy snow and gusts to 30 mph.”

This storm comes just a few days after Boise hit a nearly five-year low of minus-2 degrees near the Boise Airport on New Year’s Day. Boise saw several inches of snow last week as well.

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