Why Buffalo got so much snow last weekend

Why Buffalo got so much snow last weekend

This article was originally featured on The Conversation.

Although it’s difficult for most people to picture 6 feet of snow in one storm like the Buffalo region saw this weekend, such extreme snowfall events sometimes occur along the eastern edges the Great Lakes.

This phenomenon is known as “lake-effect snow,” and lakes play a key role in it.

It all starts with cold, dry Canadian air. As the bitterly cold air moves across the warmer Great Lakes, it absorbs more and more moisture.

Why Buffalo got so much snow last weekend
Canadian winds pick up moisture over the Great Lakes, turning it into heavy snowfall on the far shore. NOAA

I’m a climate scientist at UMass Amherst. Students often ask me how heavy snowfall can be caused by cold, dry air in the Climate Dynamics course that I teach. Here’s how it happens.

How dry air turns into snowstorms

Lake-effect snow is strongly influenced by the differences between the amount of heat and moisture at the lake surface and in the air a few thousand feet above it.

A large contrast can create conditions that help to collect water from the lake and increase snowfall. A difference of 25 degrees Fahrenheit (14 Celsius) or more creates an environment that can fuel heavy snows. This is often seen in the fall when lake water remains warm from summer and colder air begins to sweep down from Canada. Under less extreme thermal contrasts, more moderate lake-effect snows are possible every fall.

It is important to consider the wind’s path above the lakes. The more water evaporated from a lake, the farther the cold air travels. A longer “fetch”, which is the distance above water, often produces more lake-effect snow.

Imagine a wind out of the west that is perfectly aligned so it blows over the entire 241-mile length of Lake Erie. That’s close to what Buffalo was experiencing during the storm that started Nov. 17, 2022.

Why Buffalo got so much snow last weekend
Wind directions from a storm in 2016 show how lake-effect snow piles up. NOAA

An additional effect occurs when snow reaches land. The slope of land that is higher than the lake will increase atmospheric lift, which can boost snowfall rates. This mechanism is termed “orographic effect.” The Tug Hill plateau, located between Lake Ontario and the Adirondacks in western New York, is well known for its impressive snowfall totals.

In a typical year, annual snowfall in the “lee,” or downwind, of the Great Lakes approaches 200 inches in some places.

Residents from places like Buffalo are acutely aware of this phenomenon. In 2014, some parts of the region received upwards of 6 feet of snowfall during an epic lake-effect event Nov. 17-19. The weight of the snow collapsed hundreds of roofs and led to over a dozen deaths.

Lake-effect snowfall is usually restricted to a small area where the wind blows straight off the lake. Drivers on Interstate 90 often go from sunny skies to a blizzard and back to sunny skies over a distance of 30 to 40 miles.

The role of climate change

Is climate changing a factor in the lake-effect snow machine, or is it just a coincidence? To a certain extent.

Fall has warmed across the upper Midwest. Ice is what prevents lake water vapor from entering the atmosphere. It forms later than it did in the past. Warmer summer air has resulted in warmer lake temperatures into fall.

Models predict more lake-effect snow with increased warming. However, as the temperature rises, more precipitation will fall as lake-effect rain. This is a phenomenon that already occurs in early autumn and not snow.

Disclosure – Michael A. Rawlins is funded by the Department of Energy, National Aeronautics and Space Administration and the National Science Foundation .

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