Science Facts

What Is Lake Effect Snow? – Formation, Example & Facts

Lake Effect

Lake effect snow is enhanced snowfall caused by cooler air blowing over a relatively warmer lake. All of the snowiest cities around the world receive as much snow as they do. Because of their proximity to a lake or ocean, which enhances snowfall in the winter. In the United States, these are cities surrounding any Great Lakes but especially Lake Ontario, Lake Erie, and Lake Michigan. Lake effect snow is most common in the fall because land cools down much faster than water.

Meteorologists and weather enthusiasts, in general, are often interested in a wide spectrum of hazardous weather. Even those that may not be a direct threat to their region. Also, lake effect snow is often a national news story like it was for Buffalo, New York, in November of 2014. Finally, the process that produces lake effect snow is not entirely foreign to the state of Florida.

How does the lake make snow? The warm moist air over the lake rises to form clouds. Suppose the cold winds through the lower levels of the atmosphere blow in a similar direction. This causes snow to form and move over the land. With the right amount of instability and proper Winfield strong lake effect, snow bands can result in multiple inches of snow per hour lasting for hours at a time and burying cities in the process. But once the lake freezes over, lake effect snow comes to an end.

What is lake effect snow?

In a hot lake, the cold airmass blow over the lake. The lake is warmer, and it is going to warm that air mass from below. The lake needs to be unfrozen at 35, 40, 45 degrees temperature. Then the air that blows across it from the north or the west can be 10 degrees. So what does warm air do? It wants to rise.

Winter cold fronts sweep down, delivering arctic air and increasing the temperature difference between the warm waters and the cold air above it. This temperature difference is called instability which promotes air to rise. As it does that, it cools and condenses blows over the area or city.

Suddenly, the lake’s moisture mixes with the north’s cold air, and you get big clouds or snow. When it goes on land and goes uphill, you suddenly get significant lake effect snow. It can be 2 to 3 inches per hour and depending on where you are. If you’re just south of it or north of this lake effect observer, it can look like a wall of snow is coming down.

So that’s why you can be anywhere from a two to three-inch snowfall in one county and just a few miles south. You can get 30 inches in one day. It may be a couple of miles wide! You could be driving into a city, and then all of a sudden gets smacked by lake effect snow.

Lake effect snow formation & example

How does the lake effect snow form? Certain parts of the United States get enormous snowfall in the wintertime. That snowfall is called by meteorologists lake effect snow.

It’s a snowfall that typically forms around large bodies of water like Lake Michigan. Water holds heat very well. Such large water bodies like Michigan will absorb heat from the Sun throughout the year. Large bodies of water tend to release that heat very slowly. As a result, no matter how cold it gets, Lake Michigan will not freeze over completely.

Lake effect snow formation

When cold air blows over the lake from the north and west, that air is much colder than the water’s freezing point. The lower levels of the atmosphere become unstable. This promotes the air to rise. The rising air quickly condenses into building clouds within this cold airmass aloft. The clouds continue to build and move downwind with the prevailing flow. This process continues until the snow begins to fall. The snowfall can become heavy as a rising motion is further enhanced by moisture being pushed uphill as it moves ashore.

Rising motion as a result of instability forces more air into the system from the sides. When these streams of air collide, it results in even stronger rising motion. This enhancement leads the snow bands to become even more organized, and heavier snowfall rates developing the lake downwind.

Lake Michigan, however, is always somewhat above the freezing point of water. So water is constantly evaporating off the surface of the lake. As the cold air blows over the lake, it turns that warm moist air into snow that is then blown to fall on the lake’s opposite side. It is in the massive snowfalls that we call lake effect snow.

Lake effect snow bands can be associated with significant snowfall tolls and sharp gradients in these snowfall accumulations. Between the 17th and twenty-first of November 2014, persistent lake effect snow bands developed Lake Erie’s downwind. Some locations south of downtown Buffalo New York received incredible snow totals exceeding seven feet.

The same process that produces lake effect snow can also create what is known as ocean effect snow. One place common disease effect is over eastern Massachusetts. Arctic air filters down from the north over the relatively warm waters of the Atlantic Ocean. The warmer air rises and condenses, producing similar snow bands to those seen off the Great Lakes.

Although certainly not as even familiar places such as Florida may experience this phenomenon of ocean affect precipitation. As cold air filters over the Florida East Coast after passing over the Gulf Stream’s warmer waters, the stage is now set for ocean effect precipitation to form.

Lake effect facts

The greater the temperature difference between the air in the lake, the more moisture is sent to the clouds leading to even more snow. Overall the atmospheric conditions are similar for lake effect rain which starts in the late summer and generally lasts through October. Lake effect rain also requires cold air moving over a warmer lake, but there’s more to the different precipitation than just temperature.

  • First lake effect snow typically happens when there are extreme amounts of instability in the low levels of the atmosphere caused by strong fronts or deep low-pressure systems. But in Lake Effect rain events, that instability is absent.
  • Second, a much deeper layer of conditionally unstable air is usually present during rain events. Conditionally unstable sounds complicated, but it just means that a trigger is needed to start the process leading to form precipitation. For rain, this is typically an elongated area of low pressure incoming from the West. A thicker, conditionally unstable layer allows for stronger activity which can form thunderstorms.

As a result, the greatest number of Lake Effect thunder events around Lake Erie occurs from late September to mid-October when the layer of conditionally unstable air is much deeper.

  • Third, the warmer the area, the more moisture can hold. So in the winter, with frigid air, the storms hold less of a punch, higher relative humidity. And air blowing over Lake Erie produces more widespread cloud cover in Lake Effect rain than in snow. Clouds are also deeper during rain events meaning the steering of lake effect rains likely comes from a higher level.

In the example below from January of 2003, snow was reported at the shuttle landing facility at Cape Canaveral. A few other notable places in the United States that experience occasional lake effect precipitation include the great salt lake in Utah and Lake Pontchartrain in Louisiana.


Read More:

What Is Fog Made Of? – Fog Types, Causes & Formation

What Is the Rain Shadow Effect? – By Mountain Diagram

How Is Rain Formed? – Water Cycle, Cloud & Rainfall Types


Sources:

“NOAA – National Oceanic and Atmospheric Administration – Monitoring & Understanding Our Changing Planet.”
“Instability.” “Wind Shear.” “Upstream Moisture.”

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