March nor'easters

March 2, March 7, March 13 and March 21.

Those are the dates four nor’easters washed away the dunes in part of North Wildwood and dumped a large volume of precipitation over South Jersey, including a widespread 6 to 12 inches March 21.

How did this happen?

The answer, as in real estate, is location, location, location — with a dash of climate change.

A nor’easters is just like any other low-pressure system. However, the term comes from the cold, damp northeast winds that blow around a counterclockwise-spinning low-pressure system. To have a wind blowing from the northeast in South Jersey, you need it to come up the East Coast. Turns out, we sit in an ideal spot for that.

Nor’easters typically form between Cape Hatteras in North Carolina and Cape Cod in Massachusetts.

“South Jersey sits right in the middle,” said Dave Robinson, the New Jersey state climatologist.

But while South Jersey sits in an ideal spot for nor’easters, you still need a storm to bring the wind, snow, coastal flooding and rain they are known for. That is where the jet stream comes in — the river of air 20,000 to 50,000 feet high that separates warm from cold air.

“The key of the jet stream is that it evacuates the rising air. This creates updrafts, which strengthen the storm,” Robinson said.

The jet stream also helps steer the nor’easter.

In the biggest storms, the current of air moves from north to south, known as meridional flow.

Think of it like a roller coaster. The jet stream dives south from western Canada to the Southeast, before pulling back up north just off the Northeast coast. This puts the brunt of the cold, arctic air north of the jet stream right in New Jersey.

If a storm rides along the jet stream, our area becomes ripe for extreme weather.

When there’s a large temperature difference between the two air masses, the jet stream quickly moves west to east, called zonal flow. However, Jennifer Francis, a research professor at the Institute of Marine and Coastal Science at Rutgers University, said analysis shows climate change is altering the jet stream.

“The arctic is warming two to three times faster than the tropics,” Francis said. “2018 was a record low for Pacific Ocean sea ice, decreasing the temperature difference. It is all a positive feedback loop. The warm temperatures not only melt the ice but warm the water as well. As a result, it creates more north to south swings in the jet stream.”

While climate change did not directly position the jet stream off the East Coast in March, there were warmer than average temperatures in the Pacific. This helped bring a ridge (rise north) of warm air over the western United States, with a trough (drop south) of cold air over the east.

It also means a slower jet stream. In March, “the jet stream was locked into this weather pattern, where it sat just offshore. That drove the low pressure (nor’easters) off the East Coast,” Francis said.

The result? Four days filled with coastal flooding, wind, snow and rain.

It could have been five, too.

“We dodged a fifth one on March 27 and 28,” Robinson said. “It was a bona fide storm, but it just clipped Nova Scotia.”

Meteorologist

This is my first newspaper but not my first forecast for NJ. I graduated with a B.S. in Meteorology from Rutgers. Two TV internships gave me a taste for the newsroom. Then, after nearly 4 years in private NJ weather, I'm forecasting South Jersey for you.