Strongest Nor’easters Predicted to Intensify

Nor’easters, with their heavy precipitation and strong winds, pose significant threats to cities along the East Coast, often leading to devastating impacts. A new study found that the strongest nor’easters are becoming stronger, with both the maximum wind speeds of the most intense (>66th percentile) nor’easters and hourly precipitation rates increasing since 1940, suggesting an additional contribution to coastal risk in a warming world. The researchers said such upsurges have implications for coastal cities and shorelines, increasing the risk of coastal flooding and erosion.

Nor’easters, which typically form between September and April, are coastal extratropical cyclones that feed upon temperature contrast between cold Artic air and warmer, most air from the Atlantic Ocean, causing them to intensify along the East Coast. With central pressures that sometimes rival those of tropical cyclones, they represent a significant coastal hazard and are often associated with strong winds, heavy snowfall, disruption, and damage.

However, researchers believe fewer nor’easters will occur in a warmer world, because the Arctic is heating up faster than the rest of the Northern Hemisphere meaning less of a temperature contrast exists to fuel the storms. What this new study sheds light on is what will happen to the intensity of these storms, which have been understudied.

The researchers said nor’easters have historically received far less attention than tropical cyclones, largely due to challenges in documenting and categorizing these storms combined with the relatively short observational record.