Raleigh, N.C. — Severe thunderstorms rolled across the Triangle area Tuesday afternoon, the result of humid air and high temperatures combining to create heavy downpours, damaging winds and spectacular lightning.

The excessive amount of cloud-to-ground lightning in the Triangle was very dangerous, said WRAL Chief Meteorologist Greg Fishel.

"If you go outside in a situation like this, where the cloud-to-ground lightning strikes are so dense, you're doing so at your own risk," Fishel said.

A lightning flash might have been the cause of a house fire on North 7th Street in Smithfield, but the exact cause of the fire has not been determined. No word on the extent of damage. More Info     Sign up for WeatherCall

In addition to lightning, storms brought winds gusts of greater than 60 mph. 

In Cary, a toppled tree fell on top of a house on Leeward Court around 3:30 p.m. Homeowner Jennifer Schmidt-Gerber said she and her four children were home at the time, but no one was injured. 

"I was scared, very scared," she said.

The back part of the house was damaged and a storage shed and trampoline were destroyed.

In Fayetteville, the storm knocked down power lines and traffic lights near Hay Street. A large limb from a dead pine tree collapsed on a single-wide mobile home off of Bragg Boulevard.

Two people were inside at the time, but no one was hurt.

Branches and power lines were blown down in Chapel Hill as well. A large oak tree fell on top of a Driver's Ed car on South Columbia Street around 4 p.m.

The student driver wasn't hurt.

Multiple communities around the viewing area experienced downed branches, power lines and other storm-related problems.

Progress Energy was working to restore power to more than 20,000 customers in Wake County alone at the height of the storm. By 9 p.m., more than 14,000 people in Wake County remained without power.

The utility also reported high numbers of outages in Nash, Harnett, Wayne, Cumberland and Chatham counties. 

More than 8,000 people lost power in Orange County and about 4,000 lost power in Durham County.

The storms had moved south and east of the Triangle by 4:30 p.m., but Fishel said a second round of strong storms could rumble into the area from the north after dinnertime.

Fishel said the atmosphere is extremely unstable, making conditions ripe for a powerful thunderstorm that can quickly become severe.

Tuesday's storms were more widespread than those seen on Monday, when lightning ignited serious fires at two homes in Wake County, authorities said. Five fire crews from various communities responded to a blaze at 504 Gooseberry Drive in Holly Springs, which spread to the house next door shortly after 8 p.m. 

In total, Wake County emergency dispatchers took about a dozen calls on Monday regarding lightning fires.

"We're probably going to be dealing with more intense lightning today," said WRAL meteorologist Elizabeth Gardner. "Whenever you can hear thunder, you are in danger of being struck by lightning, so be careful. It's dangerous stuff."

The temperature in Raleigh hit 94 degrees by early Tuesday afternoon, with a heat index of 108 degrees. The mercury topped out at 96 degrees for the day.

The National Weather Service issued a heat advisory Tuesday morning for counties to the north and east of the Triangle. 

A heat advisory is issued when high humidity levels combine with hot temperatures to make it feel warmer than 105 degrees for more than two hours.

High temperatures will reach dangerous levels in the Triangle again Thursday and Friday, topping out near 100 degrees both days. 

"The collection of 100-degree days this year is already impressive, and it looks like we'll be adding to it late in the week," Gardner said.