A nor’easter is about to hit the Northeast in May. That’s very unusual.

Weather model depiction of the strong winds associated with a nor'easter south of Long Island on Thursday afternoon. (Ben Noll/The Washington Post; data source: ECMWF)

By Ben Noll

Nor’easters are powerful storms that form near the East Coast, driven by the strong temperature contrasts that arise when cold, continental air collides with warm, moist air over the Atlantic.

People living along the Eastern Seaboard may be familiar with these storms, but they are much less common during late spring because the temperature differences that form them tend to be weaker.