NYC Derecho? Even If Powerful Storm Doesn't Hit, City Expected To See Heavy Rains (PHOTO)

New Yorkers are gearing up for a powerful storm that has a small chance of turning into a derecho Thursday evening.

Although forecasters say a derecho is more likely to form in areas outside the city, heavy rains and winds topping 35mph are expected to sweep through the five boroughs Thursday night.

What exactly is a derecho? Jim Keeney, weather program manager at the National Weather Service, explains:

It's a cluster of thunderstorms that congeal into a line, and that line will then start moving east or southeast, and as it progresses the winds increase and produce damage along that path. A tornado, when it does occur, may be on the magnitude of a mile or two wide; a derecho could go for hundreds of miles, producing significant damage ... [and] winds in excess of 75 miles or greater and could run for hundreds of miles. A lot of people can be impacted by derechos; tornadoes are ... smaller in scale.

You may recall this amazing panorama photo taken almost exactly a year ago when another big storm, that also threatened to become a derecho, swept through the city.

Could be a good night to stay in!