Growing up in the snowy winters of Michigan, Sebastian Harkema, a University of Alabama in Huntsville (UAH) Department of Atmospheric & Earth Science PhD candidate, still remembers the first time he heard the roar of thunder during a winter storm.

While it was a rare and exciting phenomenon to witness, Harkema would’ve never guessed years later he’d be featured by National Geographic as a leader in thundersnow research.

“It’s quite an honor to be featured by National Geographic. Their yellow rectangle border is iconic. When you see it, you know you’re going to be reading about the latest advances in scientific research,” says Harkema.

For decades, scientists believed electrification within snowstorms was caused by collisions between ice crystals and graupel, a soft hail ice hydrometeor, in the presence of supercooled liquid water.

Spotlighted in National Geographic’s article, Harkema’s research funded by the Future Investigators in NASA Earth and Space Science and Technology (FINESST) program found that graupel may not play as large of a role in the electrification of wintertime stratiform events, such as nor’easters, as previous thought.

Harkema also discovered that when thundersnow occurs, the lightning associated with the wintertime event produces large, less frequent flashes.

“This is key in promoting lightning safety during thundersnow events. Large, less frequent flashes along with snow dampening the sound of thunder could pose a risk to society outdoors unaware that thundersnow is occurring during a snowstorm,” says Harkema.

Believe it or not, Harkema had no intention of studying thundersnow in graduate school. In fact, he was more excited for the opportunity to work on a winter weather project for NASA SPoRT through a cooperative agreement with UAH that would focus on winter weather.

Wanting to take advantage of other research opportunities for students in winter weather, Harkema was encouraged by his NASA SPoRT mentor Dr. Emily Berndt and NASA SPoRT’s Dr. Christopher Schultz to apply to NASA’s 2020 Investigations of Microphysics and Precipitation for Atlantic Coast Threatening Snowstorms (IMPACTS) field campaign. It was there, where Harkema was given his first opportunity to study electrification with winter storms using aircraft observations.

After the field campaign concluded, Harkema realized he wanted to research thundersnow for his PhD dissertation and applied to NASA’s Future Investigators in NASA Earth and Space Science and Technology (FINESST) program to receiving funding for his research.

Harkema has made significant contributions in thundersnow research. Harkema has written and co-authored several publications and presented his research at several conferences, winning various accolades. Most recently, Harkema presented his research on the Inhibition of Large-Scale Electrification Within Wintertime Stratiform Regions at the 2023 American Meteorological Society Conference, receiving high praise from colleagues within his field.

Harkema is planning to defend his PhD this spring and hopes to continue his research in thundersnow and electrification in summertime stratiform events post-graduation.