Noreaster

Nor'easter, sometimes written noreaster and more commonly spelled nor'easter, is a type of macro-scale coastal storm that affects the northeastern United States and Atlantic Canada. It is typically an extratropical cyclone whose strongest winds and precipitation are concentrated along the coast, with winds often coming from the northeast as the storm intensifies and wraps cold air from the land with warm, moist air from the Atlantic.

Formation and dynamics: Nor'easters usually form along a frontal zone or off the Atlantic coast when a mid-latitude cyclone develops near the coast or moves in from the Gulf of Mexico and strengthens as it tracks northeast. The interaction between a cold air mass over the land and a warmer, moister air mass over the Atlantic, aided by jet stream dynamics and Gulf Stream waters, leads to rapid intensification and a well-defined cyclone with a strong northeasterly wind field.

Weather and impacts: These storms bring a mix of precipitation that can include heavy rain, snow, sleet, or freezing rain, depending on temperatures. They commonly produce strong onshore winds, with gusts that can cause coastal flooding, storm surge, and coastal erosion, along with power outages and transportation disruptions. Inland areas may experience heavy snowfall and blizzard conditions if cold air remains entrenched.

Seasonality and significance: Nor'easters occur mainly from autumn through spring, with peak activity in winter. They are closely monitored by meteorological services due to their potential for rapid changes in weather, significant coastal impacts, and disruption to travel and commerce.