Ask A Met: What's The Difference Between Lake Effect And Lake Enhanced Weather?

This week's question comes from Morning Brief reader Russ in Pennsylvania, who asks, "What’s the difference between lake effect and lake enhanced weather?"

Meteorologist Sara Tonks: I grew up in Georgia. The most snow I had ever seen was like a couple inches. I moved up to Pennsylvania and within two weeks got my first lake effect snow. It was about one foot in less than 24 hours. That was a trip. I didn't even own a snow shovel at the time. And that's the lower side of things for lake effect snow. A lake effect snow event in 2022 brought over six feet of snow to Buffalo suburbs in about 2 days.

Which is to say, I’m not surprised a question about lake effect is coming from a reader in Pennsylvania.

Here’s the deal with the lake effect: A mass of cold air hits a warm body of water and that triggers a lot of convection because of the temperature imbalance. The temperature imbalance causes convective activity because of the upward vertical motion of warmer air rising in the atmosphere.

Then, that major temperature difference makes the snow, because the top thing, the bubble of cool air, is so cold that when the warm, wet air rises up from the body of water it becomes snow.

The Great Lakes are supreme lake effect snow territory because they get those blasts of Arctic air from Canada pretty frequently. That’s a nice dry air mass, which means again it's even further different from that water right above the lake.

But I digress. Lake effect produces these very concentrated bands of snow. One band in Pennsylvania could have whiteout conditions with multiple feet of snow and then 10 miles away could get nothing. This is very annoying for forecasters because a tiny little deviation in the angle of the wind changes where that band sets up.

The difference between lake effect snow and lake enhanced snow is simply that key word, “enhanced.” With lake enhanced snow, there's already a system coming through that is making snow. When that front moves over the warm body of water, the lake is just enhancing it.

Whereas with lake effect, upwind of the lake, there's no snow. You can even see it on satellite or radar. In the middle of the lake, it just looks like this line of clouds starts to form.

That's where the lake effect band is setting up, whereas with something bigger with lake enhanced, there's already a system coming through that is making the snow. Then, the lake is just enhancing it.

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