ABC7's Drew Tuma examines fast-moving Tahoe storm that caused deadly capsizing, extensive damage

LAKE TAHOE, Calif. (KGO) -- A powerful thunderstorm with strong winds battered the Tahoe area over the weekend, whipping up high waves.

Several people caught in the storm were killed after a boat capsized near D.L. Bliss State Park.

The wave of severe weather blew across the area and caught many off guard Saturday afternoon.

"It created an area of extreme wind in a short amount of time," said ABC7 meteorologist Drew Tuma.

He said it was sunny, beautiful and there were calm winds at 1 p.m. Saturday.

Then by 3 p.m., things changed.

"These thunderstorms started developing west of the lake. By 3 p.m., it was nothing but stormy weather, and winds closing in on 40 miles per hour, and that can create a really turbulent lake current."

MORE: 8th death confirmed after boat capsizes in Lake Tahoe during fast-moving storm, authorities say

Eight people are dead after the boat they were on capsized in large swells on Lake Tahoe Saturday afternoon. Two people were rescued.

Tuma explains, "Within a thunderstorm cloud, you can have real damaging winds, turbulent air is rising and it's falling, and that is why airplanes won't fly through thunderstorms. That air is so turbulent that'll rock a plane."

Tuma said the "falling air" is known as a downdraft.

He said if it's strong enough, it can escape the thunderstorm cloud and rush down to the ground.

"And when that downdraft hits the ground, all of that strong air is forced outward from the surface, and at times, those winds can gust over 60 miles per hour. It can be a very localized event over a small area of two to three miles, and that's likely what we saw occur around Lake Tahoe," Tuma said.

He also said thunderstorms were close enough to the lake and strong enough that some of those very strong downdrafts were able to churn up that lake water.

Tuma reminds people, "At the surface, you've got to keep your eyes to the sky, just because it's a sunny day, doesn't mean those thunderstorms can't develop later on in the afternoon, and really cause some damage."

The U.S. Coast Guard says 10 people were on the boat when it capsized. Eight people were killed. Two people were rescued.

The boaters who were killed have not been identified, according to the El Dorado County Sheriff's Office.