What is Lake-effect Snow, and Why Study It?

If you live near the Great Lakes, and especially in upstate New York, you will have most likely heard of lake-effect snow before. But elsewhere, the term is probably foreign to your ears. So what is lake-effect snow? And what is so special about it? I personally think it is a very cool weather phenomenon, although the general process behind it are relatively simple.

Lake-effect snow is simply snow that forms over a lake (in our case, Lake Ontario in the Great Lakes) due to the difference between the temperature of the lake surface and the air directly above it. Lake-effect snow occurs at large lakes all over the world, but is perhaps most prominent over the North American Great Lakes. In late autumn or early winter, before the lakes freeze over, very cold airmasses from Canada will occasionally swing down over the Great Lakes, bringing frigid temperatures to the region. The air might be 10-20 degrees Fahrenheit, while the lake water temperature might still be 40-50 degrees. This creates a situation where the lake water is much, much warmer than the air flowing over it.

Most of us know that warm air rises as long as it is warmer than the air around it. As the cold air flows over the much warmer lakes, the air in contact with the water will warm due to conduction and will also pick up lots of moisture from the lake itself. This creates a layer of relatively warm, humid air right above the water which eventually begins to rise through the cold, dry air around it. Just like with summertime thunderstorms, this rising warm air eventually cools off to the point that condensation can occur, forming a cloud, and eventually snow. If the warm air is rising fast enough, and contains enough moisture, then the snow that forms in the cloud can become very heavy in a very short period of time. This is illustrated in the photo below.

Settling In

So I have arrived in Geneva, NY for OWLeS. The hotel I am staying in sits right on the northern shores of Seneca Lake, one of the New York Finger Lakes. My window looks directly out over the lake to the east. I call that a win! Be on the ready for epic sunrise photos finding their way into this blog. In total, there are currently six of us here from the University of Wyoming - myself, our pilot, two engineers, and two other atmospheric scientists. There are eight others from UW who will be coming out at some point in the next two months, although not all at the same time.

The last 24 hours have been a rush - getting to Geneva, picking up last-minute supplies, getting food, driving to the airport to pick up equipment from our trailer, driving 2 hours to the east side of Lake Ontario to drop off and assemble some weather instruments and a snow crystal camera at one of our ground sites - it's been busy. At least I was able to hang out will some cool folks from the University of Utah while I was there. The project officially begins this Thursday, although it appears as if the weather conditions will not be favorable for lake-effect snow development until Saturday at the earliest. So we wait, although this does not mean I will be sitting around watching TV all day. I will be quite busy for the rest of the week with a variety of things.