Thunder snow is a rare event when a snow storm comes with thunder and lightning. I have now experienced thunder snow twice in my life time. The first time was during the winter of 1995-96. The thunder was so loud that it woke the whole neighbourhood. The local weather man even commented on it during the evening news.
The second time I experienced thunder snow was about five minutes ago. It was relatively warm today (I went out without my coat) despite there being snow squalls off and on during the day. There wasn't much accumulation on the road. It started snowing maybe an hour ago and it looks like there's a few inches down already.
When I saw the flash of lightning I thought that something had exploded on the utility pole at the end of our driveway but we didn't lose power. Then I heard a low grinding thudding noise. I thought a snow plow was crashing into the cars parked on our street. When I looked out the window and didn't see anything but snow falling I realised it was lightning that I had seen and thunder that I had heard.
This is all thanks to the lake effect machine which is still cranking out lots of snow. Lake effect usually slows down around this time of year but it's been so warm this winter that the waters of the Great Lakes are a lot warmer than they normally are at this time of year. We'll probably be getting lake effect snow falls well into March.