WEATHER

What causes lake-effect snow?

Nov 18, 2022, 8:30 AM
Patrick Harden clears snow from the roof of his car on Tuesday, Dec. 26, 2017, in Erie, Pa. The Nat...
Patrick Harden clears snow from the roof of his car on Tuesday, Dec. 26, 2017, in Erie, Pa. The National Weather Service office in Cleveland says Monday's storm brought 34 inches of snow, an all-time daily snowfall record for Erie. Another 19 inches fell before dawn Tuesday, making the greatest two-day total in commonwealth history. (Greg Wohlford/Erie Times-News via AP)
(Greg Wohlford/Erie Times-News via AP)

(CNN) — It takes just the right conditions to produce lake-effect snow, but when they come together, it creates some of the most extreme winter weather found anywhere on the planet. Perfectly blue skies can turn to a blinding snow storm in minutes, producing snow amounts that will bury your ruler in a couple hours.

The Great Lakes is the only place where lake-effect snow occurs in the United States, except occasionally at the Great Salt Lake in Utah, according to CNN meteorologist Brandon Miller.

But what exactly is lake-effect snow?

Miller said it happens when very cold, windy conditions form over a not-so-cold lake. The lake might be 40 degrees, he said, and the air zero degrees.

“That differential in temperatures creates some instability and the water provides a moisture source,” Miller said. “When it gets over land, it deposits water vapor as snow.”

Lake-effect snow generally doesn’t fall over the water because it needs the friction and topography of the land to bring out the snow.

Winds usually blow west to east in the Northern Hemisphere, so the lake-enhanced snow is pushed to the eastern side of the Great Lakes, Miller said.

Lake-effect snow can be very localized, especially when hills and mountains can cause these little weather systems to stall out and deposit a lot of precipitation in one spot.

“You can have 20 to 30 inches of snow, and five miles away only a couple of inches,” Miller said.

The National Weather Service webpage on lake-effect snow says that “wind direction is a key component in determining which areas will receive lake-effect snow. Heavy snow may be falling in one location, while the sun may be shining just a mile or two away in either direction.”

Upstate New York and the cities of Rochester, Buffalo and Syracuse are the hot spots — maybe they should be called cold spots — for lake-enhanced snow in the United States, Miller said.

That area is located east of Lake Erie and Lake Ontario, which have a more east-west orientation than the other Great Lakes. That means there’s more time and distance for the lake-enhanced snow to build up, Miller said. In meteorologist lingo, that’s called a longer “fetch.”

And lake-effect snow can pile up with amazing speed.

The incidence of lake-effect snow tends to decrease as we get deeper into winter, he said. The lake water becomes colder and and there’s less differential with the air temperature.

Lake Erie often freezes over, being the smallest and shallowest of the Great Lakes. “If the lake freezes, the lake-effect machine effectively shuts down,” Miller said.

The Great Salt Lake sometimes produces lake-effect snow, but not much because it’s not as big as the Great Lakes.

Japan suffers through something even bigger and badder than lake-effect snow: Ocean-effect snow, with the effects amplified because of mountain ranges.

“You can see one hundred inches in a week from the ocean-effect snow,” Miller said.

How lake-effect snow is changing

The connection between lake-effect snow and the climate crisis is a complicated one, but scientists have observed a slight increase in annual lake-effect snow amounts around the Great Lakes since 1930, and they expect it will continue to increase modestly through the middle of this century.

That increase is due to two things: Warmer lake water temperatures and a shorter amount of time that the lakes are covered in ice during winter.

When cold air blows over warmer lake water, it can pick up more moisture and lead to higher snow amounts downstream. In that same vein, if lakes are ice-free longer into the winter season, that sets up the potential for more lake-effect snow events, since lake-effect snow generally requires that the lakes are not covered in ice.

Ultimately scientists think the increase will cease — possibly around midcentury — as air temperatures continue to rise due to planet-warming fossil fuel emissions. One of the major requirements for a lake-effect snow storm is cold air. As that air becomes warmer, it will be less and less likely that it will be cold enough to produce snow.

Related: Great Salt Lake dust could be toxic, bad for snow season

Today’s Top Stories

Weather

The Great Salt Lake Collaborative in California. The team consisted of The Salt Lake Tribune, Deser...
Amie Schaeffer

The Great Salt Lake Collaborative wins $20,000 prize in ‘Local that Works’ contest

The Great Salt Lake Collaborative gains national recognition with the top prize in the 'Local that Works' contest. The collaboration is a group of 23 media organizations and community partners focused on the plight of the Great Salt Lake.
3 months ago
Chad Cranney, Assistant Wildlife Manager for the Utah Division of Wildlife Resources, pilots a fan ...
Sheri Quinn, Utah Public Radio and Ben Winslow, Fox 13 News

Many options for helping the Great Salt Lake; the simplest — use less water

Saving Utah's Great Salt Lake has become a vital issue as it sits at it's lowest level in recorded history.
3 months ago
The Great Salt Lake is pictured with a receded water line...
Mark Jones

Water levels are too low for some Great Salt Lake sensors

KSL meteorologist Kevin Eubank says the Great Salt Lake is again at a historic low, and at least one sensor is no longer in the water.
3 months ago
A University of Utah researcher says history cannot offer a complete roadmap when looking for ways ...
Carter Williams, KSL.com

What role can history play in saving the Great Salt Lake, solving Utah’s water woes?

A University of Utah researcher said stories from history can help drive current decisions about the drying Great Salt Lake.
3 months ago
A sign at the Hemenway Harbor launch ramp marks the water line at Lake Mead in 2000, contrasting wi...
Ben Winslow, Fox 13 News and Sheri Quinn, Utah Public Radio

‘To Protect and Conserve’: Las Vegas has strict outdoor watering restrictions (with fines!) Should Utah do the same?

When it comes to water use in southern Nevada, it’s common to point to the excess of the Las Vegas Strip as a prime example of waste. But Entsminger said it’s a misconception.
3 months ago
The NASA Space Launch System rocket makes its way from the Vehicle Assembly Building to its launchp...
Kristin Fisher and Jackie Wattles, CNN

NASA still planning Artemis I launch despite minor hurricane damage

NASA says another attempt to launch Artemis I into space will come next week.
3 months ago

Sponsored Articles

Happy joyful smiling casual satisfied woman learning and communicates in sign language online using...
Sorenson

The best tools for Deaf and hard-of-hearing workplace success

Here are some of the best resources to make your workplace work better for Deaf and hard-of-hearing employees.
Team supporters celebrating at a tailgate party...
Macey's

8 Delicious Tailgate Foods That Require Zero Prep Work

In a hurry? These 8 tailgate foods take zero prep work, so you can fuel up and get back to what matters most: getting hyped for your favorite
christmas decorations candles in glass jars with fir on a old wooden table...
Western Nut Company

12 Mason Jar Gift Ideas for the 12 Days of Christmas [with recipes!]

There are so many clever mason jar gift ideas to give something thoughtful to your neighbors or friends. Read our 12 ideas to make your own!
wide shot of Bear Lake with a person on a stand up paddle board...

Pack your bags! Extended stays at Bear Lake await you

Work from here! Read our tips to prepare for your extended stay, whether at Bear Lake or somewhere else nearby.
young boy with hearing aid...
Sorenson

Accommodations for students who are deaf and hard of hearing

These different types of accommodations for students who are deaf and hard of hearing can help them succeed in school.
Young woman receiving laser treatment...
Form Derm Spa

How facial plastic surgery and skincare are joining forces

Facial plastic surgery is not only about looking good but about feeling good too. The medical team at Form Spa are trained to help you reach your aesthetic outcomes through surgery and through skincare and dermatology, too.
What causes lake-effect snow?