PORTLAND, Ore. (KOIN) — First things first, you’re going to want to listen to the video above. This was taken from the front door camera of Portland resident, Danielle Prentice, Sunday afternoon. You can hear a loud boom and then see how quickly the person runs inside.

Remember — when you hear thunder roar, head indoors.

You may have heard the rattle too. KOIN 6 News had multiple reports from viewers around the region expressing how loud this noise was. This was indeed a vocal shout of thunder, and if you didn’t see the flash of lightning, it may have seemed much more than your typical thunderstorm.

The lightning strike occurred in southwest Portland, being heard through Hillsdale, Raleigh Hills and Beaverton, along with the Portland area.

WHAT HAPPENED?

We had what is an uncommon cloud-to-ground positive lightning strike. This type of lightning strike usually comes from much higher in the cloud and covers more air.

A positive stepped leader will meet with a negative streamer from the ground (video below).

Most lightning is a negative charge that comes from lower at the base of the thunderstorm. This process moves at lightning speed! Now you know that not all lightning bolts are the same.

WHY WAS IT SO LOUD?

Positive lightning bolts really heat up the air as they cover more space. They pack more of a punch than your typical negative lightning bolts. Because of that heat generated, that acoustic shock can be a vociferous clap of noise.

According to NOAA, positive cloud-to-ground lightning strikes account for only 5%. This was not only an unusual bolt of lightning due to the particular setup we had Sunday, but the type of storms we endure in the PNW are typically tame.

You can learn more about how the sound of thunder travels below.