Tornado watch on Long Island: What to know about the storms

Though they are rare, tornadoes can form on Long Island.

Nassau County and New York City are under a tornado watch until 9 p.m. on Tuesday, which means that the weather conditions are right for a potential tornado. Before 3 p.m., the National Weather Service issued tornado warnings for several counties in New Jersey and for Sullivan County in upstate New York. A warning means a tornado has been spotted or seen via weather radar.

Newsday answers your questions here.

What is a tornado?

A tornado is a column of air that rotates violently from the base of a thunderstorm to the ground, which is usually characterized by its funnel-shape cloud. It can cause severe damage very quickly.

What causes tornadoes?

Here's how the  National Oceanic and Atmospheric Administration puts it: "A tornado forms from a large thunderstorm. Inside thunderclouds, warm, humid air rises, while cool air falls -- along with rain or hail. These conditions can cause spinning air currents inside the cloud. Although the spinning currents start out horizontal, they can turn vertical and drop down from the cloud - -becoming a tornado."

Why are tornadoes more common in the middle of the country?

The conditions are better because the cold, dry air from Canada meets the warm, moist area from Mexico, according to experts.

What do you do if you are at home during a tornado? 

Go to the lowest part of your home possible, such as a basement, or a small interior room. You must stay away from windows, the National Weather Service says.

What do you if you're on the road?

Here is the verbatim advice from the NWS: "If caught outside, find shelter in a ditch or remain in your vehicle and cover your head for protection. Do not take shelter under a highway overpass, where wind speeds can increase due to a tunneling effect. It is best to not put yourself or others in a situation where no sturdy shelter is available."

When did Long Island last experience a tornado?

Long Island last saw tornadoes in 2021, when six tornadoes formed in a single storm for the first time in the Island's recorded history, meteorologists said. During that Nov. 13, 2021, storm, tornadoes were confirmed in areas such as North Bellport, Hampton Bays, Woodmere, Hempstead and Levittown. Tornadoes were also reported in East Islip and Westhampton.

Most of the tornadoes were at a class EF-0, the lowest strength registered, with wind speeds between 70 and 80 mph. A stronger tornado, with winds up to 110 mph, was reported in Shirley and Manorville. The storms caused extensive damage, including downed trees and damaged houses.

By John Asbury

john.asbury@newsday.comJohnAsbury

John Asbury is a breaking news and general assignment reporter. He has been with Newsday since 2014 and previously worked at The Press-Enterprise in Riverside, California.