This text was initially featured on The Dialog.
It’s arduous for most individuals to think about 6 ft of snow in a single storm, just like the Buffalo space noticed over the weekend, however such excessive snowfall occasions often occur alongside the jap edges of the Nice Lakes.
The phenomenon known as “lake-effect snow,” and the lakes play a vital function.
It begins with chilly, dry air from Canada. Because the bitter chilly air sweeps throughout the comparatively hotter Nice Lakes, it sucks up increasingly moisture that falls as snow.
I’m a local weather scientist at UMass Amherst. Within the Local weather Dynamics course I train, college students usually ask how chilly, dry air can result in heavy snowfall. Right here’s how that occurs.
How dry air turns into snowstorms
Lake-effect snow is strongly influenced by the variations between the quantity of warmth and moisture on the lake floor and within the air a number of thousand ft above it.
A giant distinction creates situations that assist to suck water up from the lake, and thus extra snowfall. A distinction of 25 levels Fahrenheit (14 Celsius) or extra creates an atmosphere that may gasoline heavy snows. This usually occurs in late fall, when lake water remains to be heat from summer time and chilly air begins sweeping down from Canada. Extra reasonable lake-effect snows happen each fall beneath much less excessive thermal contrasts.
The wind’s path over the lakes is vital. The farther chilly air travels over the lake floor, the extra moisture is evaporated from the lake. A protracted “fetch” – the gap over water – usually leads to extra lake-effect snow than a shorter one.
Think about a wind out of the west that’s completely aligned so it blows over the complete 241-mile size of Lake Erie. That’s near what Buffalo was experiencing in the course of the storm that began Nov. 17, 2022.
As soon as the snow reaches land, elevation contributes an extra impact. Land that slopes up from the lake will increase elevate within the ambiance, enhancing snowfall charges. This mechanism is termed “orographic impact.” The Tug Hill plateau, positioned between Lake Ontario and the Adirondacks in western New York, is well-known for its spectacular snowfall totals.
In a typical yr, annual snowfall within the “lee,” or downwind, of the Nice Lakes approaches 200 inches in some locations.
Residents in locations like Buffalo are keenly conscious of the phenomenon. In 2014, some elements of the area acquired upwards of 6 ft of snowfall throughout an epic lake-effect occasion Nov. 17-19. The load of the snow collapsed a whole lot of roofs and led to over a dozen deaths.
Lake-effect snowfall within the Buffalo space is usually confined to a slim area the place the wind is coming straight off the lake. Drivers on Interstate 90 usually go from sunny skies to a blizzard and again to sunny skies over a distance of 30 to 40 miles.
The function of local weather change
Is local weather change taking part in a job within the lake-effect snow machine? To an extent.
Fall has warmed throughout the higher Midwest. Ice prevents lake water from evaporating into the air, and it’s forming later than previously. Hotter summer time air has led to hotter lake temperature into fall.
Fashions predict that with further warming, extra lake-effect snow will happen. However over time, the warming will result in extra of the precipitation falling as lake-effect rain, which already happens in early fall, moderately than snow.
Disclosure: Michael A. Rawlins receives funding from the Division of Vitality, the Nationwide Aeronautics and Area Administration, and the Nationwide Science Basis.