Has this ever happened to you? You suddenly find yourself driving in blinding snow. Then as quickly as it came, it clears up. What causes that phenomenon?
A snow squall is defined as a sudden, heavy snowfall that is shorter in duration than a blizzard but contains many of the same features, including gusty winds, potential whiteout conditions and heavy snow. You could be in just a snow squall and still be blinded by driving snow.
Snow squalls are common in areas that experience lake-effect snow, but they can also form as a part of frontal systems. Areas of lake-effect snow affected by snow squalls are commonly known as snowbelts. Squalls in those regions can last longer than frontal squalls due to the nature of lake-effect snow bands remaining more stationary, as opposed to a constantly moving front.
Frontal snow squalls are similar to normal frontal squall lines that bring thunderstorms, only they occur in the winter. Frontal snow squalls usually last less than half an hour and are relatively narrow but intense. It’s not uncommon to have multiple squall lines following in quick order.
One defining feature of frontal snow squalls is that they’re relatively short-lived. In many situations, it’s clear shortly after the squall passes.
A normal snowstorm differs from a snow squall in several ways, including duration and formation. A snowstorm is not defined by any specific characteristics, just a large amount of snow and wind. Technically, a snow squall is a type of snowstorm.
Eggert works in the Indiana State Climate Office. He writes from West Lafayette, Ind.