Nor’easter Defined: The big Northeast snow maker

Weather Glossary

Featured image courtesy of NOAA National Environmental Satellite, Data, and Information Service (NESDIS)

ROCHESTER, NY (WROC) – A Nor’easter is a large storm system that impacts the northeast coast of the U.S. where the winds typically flow easterly off the coast. Makes a good amount of sense right? However, these storms can do a lot more than just cause easterly winds. Nor’easters are known to produce large amounts of rain, snow, wind, and sometimes mixed precipitation types that can create rapidly changing weather and hazardous road conditions. Snow totals from these events can range from just a few inches in one area to several feet in another.

A few common Nor’easters to impact the east coast include the Blizzard of 88’, the March 1993 Superstorm, the storm to hit Boston back in 2015, and the “Ash Wednesday” storm in March of 1962. All of these storms caused tremendous impacts and property damage especially to coastal areas.  

March 1993 Storm – “The Storm of the Century”

Did you know? Nor’easters can occur during any time of the year, but are most frequent during the months of September to April.

The east coast is a prime breeding ground for these dynamic storm systems as this area is known for getting frequent intrusions of cold, arctic air from up north mixing with warm, moist air masses from the Gulf. It’s these temperature differences across the colder land and warmer ocean that fuel the energy needed for these storms to get going. The ocean waters off the east coast are able to stay warm during the Northern Hemisphere winter due to the continuous Gulf Stream that pumps warm, tropical waters northward all year round.

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There are 2 types of Nor’easters characterized by where they originate:

Miller Type A

These storms develop from the Gulf and eventually along the eastern seaboard. They draw most of their energy from large temperature gradients and steep jet streams. These storms are known as the “classic” style nor’easters, and usually produce a wide range of snow amounts based on the path they carve through the region. Areas of Pennsylvania typically end up with some of the heaviest snow amounts.

Miller Type B

These storms develop in a slightly different manner and in a different location in the U.S. They typically develop from out west across the Central Plains and the Eastern Rockies and become very well developed surface lows. As they trek eastward across the Appalachian Mountain chain, they weaken and reform as a redeveloped surface low off the coast. This is where the surface low pressure uses marine/land temperature differences to fuel its energy, similar to a Miller Type A storm.  

Snow amounts are usually a bit more uniform and evenly distributed barring any lake enhancement to come after it. Depending on the track of the low, they can easily change and make all the difference with snow totals making a few inches become a few feet just miles apart.

The most favorable path for Nor’easters to take that affect WNY would be when the low pressure carves a direct path from central Pennsylvania into eastern New York. With enough cold air and wrap around moisture we often get additional snow accumulations from lake effect snow.

Typically, a surface high pressure is located just to the north of these low pressure systems that ride up the coast. It’s the clockwise flow around these highs that pumps in cold air at the surface, and can heavily inflate snow totals. The amount of cold or warm air in place as well as the availability of enough moisture can affect snow ratios, which in turn heavily influence snow amounts. These areas of high pressure if strong enough can also prevent snow from initially falling if there is enough dry air being fed into the lower levels of the atmosphere. This can create the phenomenon known as virga as snow falls from the clouds, but never reaches the ground. The influence from nearby high pressure systems are important to note when forecasting, and can also heavily impact snow amounts in these highly complex systems.

Copyright 2021 Nexstar Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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