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Weekly Weather Event -Week of November 30th

December 4, 2020

A nor’easter is expected to bring rain and snow all along the East Coast this weekend, with a six to eight inches expected in New Hampshire and a foot of snow possible in northern and western Maine. Forecasts are less certain about the positioning of the rain-snow line, which will be important for determining whether or not some of the larger cities in New England see rain or snow. The system is expected to have the strongest impacts Friday into Saturday as the storm intensifies before moving into New Brunswick and Nova Scotia, Canada. Depending on how this nor’easter develops, it could deepen as much as 24 millibars in the span of 24 hours, which would classify this storm as a bomb cyclone.

While popularized in recent years, the term ‘bomb cyclone’ refers to a mid-latitude cyclone (sometimes called an extratropical cyclone or nor’easter) in which the pressure at the low drops incredibly rapidly, at least 24 millibars within the span of 24 hours. This is known as explosive cyclogenesis or ‘bombogenesis’, and it is known to produce storms that bring heavy amounts of precipitation. Strong winds also typically accompany bombogenesis, as warm, moist air is pulled north along the eastern part of the cyclone and cold, dry air is pulled south along the western part of the cyclone.