Nor’easter hits US: What it is, why this one is particularly disruptive, and its likely El Niño link

The US East Coast is being battered by a storm where wind, water and time have combined to push a familiar weather system into major disruption.

A strong nor’easter stretching from Washington, D.C. to Maine has forced the cancellation of hundreds of flights and left more than 100,000 homes and businesses without power at one point on Saturday. Tens of thousands of people in New Jersey, Connecticut, New York and Pennsylvania were left without electricity, with fallen trees, branches and wires causing outages.

The National Weather Service said the storm would continue to bring coastal flooding, dangerous rip currents, strong wind gusts and heavy rain across the Mid-Atlantic and New England through Monday.


New York and New Jersey declared states of emergency on Friday in counties expected to face the worst conditions, including New York City. Connecticut also activated its Emergency Operations Center.

Also read | Nor’easter hits US; grounds flights, cuts power

The immediate risks include flooding, high surf and damaging winds. But the storm is also drawing attention to how the broader El Niño pattern could shape weather conditions across the US in the months ahead.

What is a nor’easter?

A nor’easter is a powerful storm system that develops along or close to the US East Coast and generally travels towards the northeast. Its name comes from the northeasterly winds that can lash the coast as the storm strengthens.

These systems develop when contrasting air masses meet. Cold air from the north interacts with warmer, moisture-rich air from the south and the Atlantic. The resulting temperature difference can provide the energy needed for a storm to intensify.

Nor’easters can produce several hazards at the same time. Heavy rain can overwhelm drainage networks and contribute to flooding inland. Powerful winds can uproot trees, damage structures and bring down electricity lines.

Along the coast, the danger can be greater. Storm-driven water can combine with high tides and push seawater into roads and coastal communities. Strong, sustained winds can also generate large waves, intensify surf and speed up erosion of beaches and dunes.

Why is this storm particularly disruptive?

One of the biggest concerns with the current system is its slow movement.

A fast-moving storm may pass through an area relatively quickly. A slower nor’easter can keep coastal communities exposed to strong winds, high waves and elevated water levels for much longer. That increases the potential for flooding, power failures and transport disruption.

Also read | New York, New Jersey face major flooding, 60 mph winds and power outages

The highest tides were expected north of Atlantic City from Saturday night into Sunday, increasing the risk of widespread flooding in coastal and bayside areas. Tens of millions of people remained in the storm's path as emergency agencies prepared for additional outages and flooding.

The storm has also arrived earlier than would normally be expected for a nor’easter of this strength, according to forecasters.

Where are nor’easters most commonly seen?

Nor’easters are particularly associated with the US Northeast and Mid-Atlantic coastline. Their typical zone stretches from areas around Washington, D.C., northwards through New York and New England.

The combination of cold continental air, warmer Atlantic waters and the atmospheric conditions over the East Coast makes the region especially conducive to these storms. They are a familiar feature of the colder months, when temperature contrasts can be pronounced.

What does El Niño have to do with it?

The current weather pattern also has a broader climate backdrop: El Niño.

El Niño is a natural cycle in the tropical Pacific in which unusually warm ocean temperatures alter atmospheric circulation well beyond the Pacific. This year's El Niño is particularly strong and is influencing weather patterns across the US.

It does not directly cause every individual storm. But in the Northeast, El Niño can shift the Pacific jet stream southward. That configuration can help supply moisture and energy to storms developing near the southeastern US before they move north along the East Coast.

Nor’easters also appear to occur more frequently during El Niño years, according to a New York Times report.