The East Coast of the United States hasn’t experienced a hurricane this year, but the storm trudging up the Northeast this weekend may feel like one in some places. This storm is technically a nor’easter, a type of storm that more commonly stirs visions of heavy snow and plunging temperatures. So what’s the difference, and why is this a nor’easter if it’s not going to snow?

“Nor’easter” applies broadly to storms that move along the Eastern Seaboard with winds that blow from the northeast. These types of storms typically occur between November and March. A nor’easter in September is relatively early, but not unheard of. A nor’easter gets its energy from colliding air masses, like cold, dry air and warm, moist air. On satellite images, it often looks like a large comma. The long tail is the cold air wrapping around the storm’s center — that’s what causes thunderstorms to form — while the comma head is where the warm, moist air wraps around.

These storms can be enhanced by the jet stream, a ribbon of very strong winds at the cruising altitude of commercial airplanes. Often, the National Weather Service will avoid using the word “nor’easter” entirely if the storm doesn’t have a major snow component, because residents in the Northeast so strongly associate the term with snow. Dominic Ramunni, a meteorologist with the Weather Service in New York City, said that the local weather offices and the national centers of the Weather Service had a call Thursday and agreed to all use the same term for this storm so there wasn’t confusion in the media. So, they all began using nor’easter on Friday instead of coastal storm, because nor’easter was already being widely used. Mr. Ramunni said that while weaker than some systems this past year in terms of precipitation and winds, the coastal flooding could rival some of the worst events in the past several years.