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Tropical storms can be as dangerous as they are fascinating, but at least they have the courtesy to show up predictably, over warm ocean waters near the equator. Except for the case of a 1996 storm nicknamed Hurricane Huron.

It was amazingly similar to a tropical storm, but it formed hundreds of kilometers away from the tropics . In a lake. To make a tropical storm you need a bunch of warm, moist air.

Under certain conditions, that air will rise and form a low-pressure zone underneath it. Then, more air will come rushing into the gap. That air will also rise, and the process will repeat.

For that column of air to really stick around, though, it needs a consistent source of warm, wet air, which these storms get from the oceans of the tropics. As all that warm air rises, it cools, spreads out, and creates a spiraling cyclone of rainclouds. And as the storm builds, winds and rain intensify until you have a huge spinning cluster of thunderstorms, typically surrounding a calm, central eye.

If sustained winds reach over 63 kilometers per hour, it's officially classified as a tropical storm. And if those winds go over 119 kilometers per hour, you've got a hurricane. Or you might call it a typhoon, or a tropical cyclone, depending on where in the world you live.

It's not unusual for tropical storms to move over land, but they typically weaken once they leave the warmth and moisture of the ocean. Now and then over the past century, slowly-dying storms have traveled as far inland as the. Great Lakes.

But what's so unusual about so-called Hurricane Huron — or the “Hurroncane” — is that it formed far from the ocean but had the structure of a true tropical storm. In mid-September 1996, a normal storm system moved over the Great Lakes. Like many systems in the northern U.

S., it initially had cold air at its center. But the conditions were just right for some very strange weather. As it moved across the region, the storm stalled over Lake Huron, which sits at the border of Michigan and Ontario.

And since this large lake — like the oceans — is at its warmest in August and September, it began feeding the storm warm, moist air. By September 14th, the cold center of the storm had turned warm and formed a rising air column that fueled a spiraling system of storm clouds. Viewed through satellite images, it looked just like a hurricane — it even had a calm eye in the center!

At its peak, this storm produced enough rain to cause flooding in some places, and sustained winds reached over 64 kilometers per hour. Not only did those winds create nearly three-meter-high waves on the lake surface, they're also tropical-storm-force winds! Meteorologists say this is the first time a storm like this had ever been seen over the Great Lakes, and it seems to have taken a handful of unusual conditions to make it happen.

Which, in some ways, is kind of reassuring. Now, even though the storm is jokingly called Hurricane Huron, it wasn't technically a hurricane because the winds weren't fast enough. And it also wasn't technically a tropical storm, since it… wasn't in the tropics.

But there doesn't seem to be a quick, easy term for it, so we'll just call it what it was: a very strange week on Lake Huron. Thanks for watching this episode of SciShow! If you want to learn more about hurricanes and other kinds of extreme weather, we can hook you up.

Like, if you've ever wondered why we don't just nuke hurricanes — which people do ask from time to time — you can watch our episode with the answer after this. [ outro ].