If you hear a few rumbles of thunder early Friday morning, don’t think you’ve imagined it. The snowstorm headed toward Ann Arbor may include the relatively rare phenomenon of thundersnow.

The rapid upward movement of air can charge particles during a snowstorm, creating lightning and thunder, said Bryan Tilley, a National Weather Service meteorologist in White Lake Township. It’s essentially the same thing that happens during a summer storm. It just happens a lot less frequently in the winter.

Tilley said only a few rumbles of thunder are expected, and they’re most likely to occur during the height of the storm, now expected to come between 3 and 9 a.m. Friday.

The weather service has issued a winter storm warning for Washtenaw County effective from 10 p.m. Thursday to 7 p.m. Friday. Tilley said the storm will start off with rain in the Ann Arbor area early Thursday evening. The rain will mix with snow later before changing over to all snow around 10 p.m.

The weather service expects a total snow accumulation of 4 to 6 inches in the Ann Arbor area by midday Friday. Blowing snow may continue to make travel hazardous throughout the day Friday.

You can watch a video of Weather Channel meteorologist Jim Cantore being surprised by thundersnow below: