New England Sees First 'Derecho' Storm In Quarter-Century

Last week's fast-moving storm system that left more than 200,000 households without power in Rhode Island and Massachusetts was officially ruled a "derecho," or powerful storm system, by the National Weather Service. New England hasn't had this type of storm as a region in 25 years.

Derechos — pronounced deh-REY-chos — are fast-moving bands of thunderstorms marked by powerful, destructive winds, the National Oceanic and Atmospheric Administration explained.The systems form when humid air from a thunderstorm combines with drier air around it, causing the water in the air to evaporate quickly, cooling the air quickly. The cold air then sinks to the ground, creating strong winds known as downbursts. The downbursts can then make the storm stronger by sucking more dry air into the storm, making the winds more powerful and wide spreading. To be categorized as a derecho, the storm's damage must stretch at least 240 miles, according to NOAA.

This type of storm is uncommon in New England. According to the National Weather service, the last one recorded in the area was in parts of New York and Connecticut in May 2018. However, it's been 25 years since the whole region saw this type of storm in summer 1995.