ROY, Utah — Early Tuesday morning, at approximately 2 a.m., many KSLTV viewers in Roy and Ogden were rocked awake by thunder and lightning. When they looked outside, it was a blizzard, not a rainstorm: a rare occurrence of thundersnow.

“I just saw a huge flash that lit my whole room up,” explained Rachel Tarr of Roy.

She was awake when the “thundersnow” blew through.

“I was surprised because I have blackout curtains because I work graveyards but from the outside, it lit my whole room up,” Tarr said.

And when she looked outside.

“It was a blizzard, and then I counted about one or two seconds, and I heard a huge boom of thunder, and it was kind of like that for about five minutes,” Tarr said.

At first, she thought it might be a problem with a power line or transformer.

“I’ve never, ever seen lightning when it’s snowing. And I’m like, ‘Is this a thing?’” Tarr recalled.

She went online and discovered what she was experiencing.

“’Thundersnow.’ It even sounds crazy,” Tarr said with a laugh. “It sounds as crazy as it seems.“

“Pretty amazing stuff. It’s a rare occurrence,” said KSLTV Meteorologist Matt Johnson.

He said layers of unstable air created extra lift in the storm. That produced extra snow and caused enough static electricity for lightning.“Last night, what we saw was there was a little bit of daytime heating before that storm rolled in during the day, and we also brought in some really good dynamics, some extra lift to help lift those particles of air high enough that we could build essentially a thunderstorm,” Johnson explained.

It’s also unusual to hear the thundersnow because the sound does not carry well in a snowstorm.

“You can only hear it if you’re within 2 miles,” the meteorologist said. “So, for the folks that saw it, or heard it, within a 2-mile radius of that storm, that’s where they had to be.“

Johnson estimates there are only about five storms each year in Utah that could produce thundersnow conditions.