© Associated Press
Were the eerie flashes of blue light similar to that in the picture above thundersnow — or something else?
Eerie flashes of blue lit up the snowy sky during this week's powerful coastal storm, but no one seems to know for sure what caused it.

Howard Bernstein, morning meteorologist at WUSA 9 in Washington, said he believes the lights were lightning strikes associated with "thundersnow."

The National Weather Service reported frequent lightning with Wednesday's storm, but said those who saw the flashes of light would have also heard thunder, and that wasn't the case around Prince William.

Bernstein says that's not necessarily true.

"I've given this a little bit of thought (and I also did a little research). I believe we were seeing lightning that was refracted by all of the ice crystals/snow flakes to give it more of a blue appearance," he said this morning in an e-mail. "Also, the thunder was probably quite muffled by all of the snowflakes, so if you weren't very close to the lightning, you probably couldn't hear the thunder."

Another possibility?

The storm knocked hundreds of trees onto power lines and blew transformers, leaving more than 10,000 in the dark and cold. But there were too many flashes of blue to attribute to transformers.

Arcing power lines struck by trees is another theory, but power company officials seemed to think not.

"I'll have to ask our engineers and get back to you, but I don't think trees hitting power lines was the cause," NOVEC spokeswoman Priscilla Knight said in an e-mail this morning. "I promise to find out!"

Stay with as we try to get the bottom of the mysterious lights. You can also follow a discussion of the lights, and read about what people saw, on our Facebook page at