Thunderstorms in the summer and in the winter have a few similarities, though the forms of precipitation are completely different. In both cases, warm air produces moisture, which condenses and forms clouds. This results in the warmer air lying on the Earth’s surface with colder air higher up.
If this warm air rises, it creates instability and forces some of the water molecules to lose electrons and other molecules to take them. This transference of electrons causes charges in the atmosphere and then electrification, which is discharged in the form of lightning.
Thundersnow occurs when warmer air causes instability to subzero temperatures. Rapidly cooled liquid water mixes with larger ice particles and ice crystals. These interactions generate lightning.
The thunder associated with these storms is created through the quick cooling and contraction of the air that is heated by lightning.
Where Thundersnow is Usually Found
Thundersnow can be found in mountainous areas such as the Rocky Mountains in the U.S. and Canada. Warm air pockets become trapped due to the extreme variances in elevation.
Large bodies of water, such as the Great Lakes, can cause thundersnow when cold air blows over the warmer water. This is where lake effect snow is a common occurrence during the winter.
Thundersnow can occur in areas that are not in the mountains or large, warm lakes, but it happens less often. Rather than the source of warm air hovering at ground level, it is at higher altitudes of 10,000 feet or greater. It usually takes place in the Northeastern, U.S., the Maritimes in Canada and the Great Plains.
Characteristics of Thundersnow
When there is thunder and lightning during a snowstorm, it could mean that heavy snow may occur. According to Scientific American, “a 30-year study of snowfall found that when lightning is observed during a snowstorm, there is an 86 percent chance that at least six inches (15 centimeters) of snow will fall within 70 miles (113 kilometers) of the flash.”
Thundersnow storms are usually intense because they don’t move quickly. As a result, they bring heavy snowfall and many times, whiteout conditions.
One of the most famous thundersnow storms was the blizzard of 1978 where over three feet of snow fell in the Northeast U.S. and wind gusts of over 110 mph caused widespread flooding on the Atlantic seaboard.
Another thundersnow storm occurred in 1993 and it was named the Storm of the Century. The average snowfall was two to three feet in the Northeast U.S. and Eastern Canada. The cold weather spread south and there was snow reported in northern Florida.
Sources:
Swaminathan, Nikhil. Thunder, Lighting and... Snow. Scientific American. March 4, 2009. Accessed December 14, 2010.
The Northeast Blizzard of 1978. Hurricanes,Blizzards,Noreasters.com. Accessed December 14, 2010.
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