What is storm snow? The strange weather phenomenon that rumbles on the East Coast and the Midwest

A rare weather phenomenon rumbled across several eastern and central U.S. states this weekend as Arctic air continues to bring heavy snowfall and frigid temperatures to millions of Americans.

Thundersnow, also known as winter Thunderstorm occurs when a snow storm is accompanied by thunder and lightning. As of Monday (Jan. 6) morning, the phenomenon has been reported across much of the southern Midwest, as well as Maryland, Virginia, and Washington, DC.

The National Weather Service (NWS) in St. Louis, Missouri, shared satellite images taken from POTGOES-East in space shows lightning in Arkansas, Kansas, Oklahoma and Missouri on Sunday (Jan. 5).

“We are getting snow storms and sleet,” NWS representatives wrote in a post on X, formerly Twitter. “This just underlines that snow and sleet rates are quite high – avoid travel if possible!”

The green spots in this satellite image are lightning bolts seen from GOES-East in space! That means…we’re getting thunder, snow, and sleet! This just underlines that snow/sleet rates are quite high – avoid traveling if possible! pic.twitter.com/8I9sSVfXVoJanuary 5, 2025

Meanwhile, images of Kansas meteorologist Jim Cantore reacting to the rare phenomenon have received thousands of views on the site.

Thunder in Kansas. We got it baby! Great day at the office! Live with @JimCantore on @weatherchannel pic.twitter.com/m1zJxwQdIlJanuary 5, 2025

What causes snow storms?

Storms occur when warm, moist air rises and condenses into cooler, drier air above it, forming towering cumulus clouds. Within these clouds is a combination of light ice crystals, which float upward, and soft hail known as graupel, which is denser and falls downward. This causes both particles to collide with each other, causing electrons to transfer from the ice crystals to the graupel. The end result is a cluster with positively charged ice crystals on top and negatively charged graupel on the bottom, according to the National Oceanic and Atmospheric Administration (NOAA).

This generates a negative charge at the base of the cloud, repelling electrons from the Earth below it. The difference in charge between the cloud and the ground increases until finally the potential energy is discharged in the form of lightning.

The energy from this blow heats the surrounding air, causing it to explode outward and creating the rumbling sound we know as thunder.

Thundersnow occurs when this weather system occurs in the middle of a snowstorm.

Why are blizzards so rare?

“Storms form more easily in summer, when the atmosphere is warmer and can hold more energy and moisture.” Jon Shonka senior scientist at the UK Met Office and researcher at the University of Reading told Live Science in an email. “In winter (especially when the weather is cold enough for snow to fall), there is much less energy in the atmosphere and much less surface heating.”

In the rare cases that snowstorms do occur, they tend to occur around the Great Lakes. “In the United States, snowfall occurs most frequently in the central part of the country, in the Intermountain West, and throughout the Great Lakes region.” Jesse Ferrellsaid meteorologist and AccuWeather senior weather editor. AccuWeather “Intense lake-effect snow bands, which have rapidly rising pockets of air due to the strong contrast between cold air aloft and warm lake water, often produce snowstorms.”

However, FOX Weather meteorologist Kendall Smith, who saw the phenomenon in Kansas City on Sunday, said it was very unusual to see snowstorms this far south. describing the event as “historic”“.

The cold weather the United States is currently experiencing has been driven by large-scale changes in atmospheric pressure and a change in the band of strong winds that normally keep cold air in the Arctic, known as the polar vortex. This change causes frigid air to sink much further south than normal, resulting in the frigid temperatures the United States is currently experiencing. And when this blast of frigid air collides with warmer tropical air to the south, it can create the conditions for a snowstorm.

“A significant increase in moisture rising from the Gulf of Mexico was ingested by the developing low pressure and then rose vertically to induce elevated instability.” Jose Weissa NOAA Weather Prediction Center forecaster told LiveScience in an email. “Where atmospheric rise was most pronounced (generally on the north/northwest side of these intense cyclones), this resulted in an intense band of snow accompanied by lightning and thunder – snow!”

Is the snow storm dangerous?

“Like any storm that produces lightning, snow can be dangerous,” Weiss said. “However, the lightning and thunder that accompany a snowstorm are usually less frequent and less intense than in summer storms.”

Unlike summer storms, where thunder can be heard miles away, snow tends to muffle its sound, limiting the distance at which it can be heard. Therefore, people may be less cautious of an impending storm and be more at risk of unexpected lightning strikes.

Shonk added that while the rate of lightning strikes during a winter storm is much lower than during summer storms, they can also be more damaging.

However, both Weiss and Shonk said the biggest risk for blizzards is the heavy snowfall that accompanies them. “Snowstorms typically occur only during the heaviest snowfall,” Weiss said, which can lead to poor visibility and hazardous travel conditions.

As of Monday (Jan. 6), winter storm warnings were still in effect across the Central Plains to the Mid-Atlantic, and disruptive storm conditions were expected to last into Monday night, the NWS said. A state of emergency was declared in Arkansas, Kansas, New Jersey, Missouri, Kentucky, Virginia and West Virginia, and 18 inches of snow fell in some parts of Kansas overnight. The NWS also predicts Up to 12 inches (30 centimeters) of snow Monday night across the Mid-Atlantic, including Washington, D.C.