The Science Of Thundersnow In A Nor’easter

A Nor’easter is typically a cyclone arising due to strong winds blowing from the Atlantic Ocean hitting the east coast of the northern hemisphere. Owing to the counterclockwise rotation of cyclonic air mass, these winds tend to blow in the northeast-to-southwest direction.

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In the US, Nor’easters usually develop between Georgia and New Jersey reaching maximum intensity over New England. Typically, such storms originate as a low-pressure area forms within 100 miles (160 km) of the shore between North Carolina and Massachusetts. Nor’easters may hit the affected areas with heavy rain or snow, strong winds, coastal flooding, and rough seas.

From March 20th to 22nd, 2018 – a powerful nor’easter, the fourth in less than three weeks, affected the Northeast United States. The Southern United States saw a severe weather outbreak on March 19th. which had later moved off to the North Carolina Coast on 20th March. It finally dissipated, spreading freezing rain and snow into the Mid-Atlantic States later that night.

At the height of the storm, snowfall rates of up to 5 inches per hour were reported in Islip, New York. Central Park saw 8 inches and over 12 inches was reported in locations on Long Island, in and around New York city & in parts of New Jersey.

A rather rare and peculiar phenomenon known as thunder-snow accompanies the Nor’easter in the US. Here’s all you need to know about them.

What is Thundersnow?
While similar to a thunderstorm, the one difference is that thundersnow has snowfall as the primary precipitation, instead of rain. Although known to be a rare phenomenon, thundersnow is rather common in the Great Lakes area of the United States and Canada, the mid-western United States and the Great Salt Lake. March is the month of thunderstorms in the US.

One unique feature of thundersnow is the suppression of the sound of thunder due to the suspended and deposited snowfall in the wind. The thunder accompanying thundersnow can barely be heard within a 2-3 mile radius, unlike a typical thunder that can be heard for many miles.

Scientific causes of Thunder-Snow
Research has shown that late winter and early spring are a favorable time for thundersnow. That’s because the basic ingredients for thundersnow – a mass of cold air over warm and a layer of moist air right above the ground – are fulfilled during this time.

The sun heats the ground and pushes masses of warm, moist air upwards creating unstable air-columns. The moisture condenses to form cumulonimbus clouds – dense, towering vertical clouds, forming from water vapor carried by powerful upward air currents. For thundersnow to occur, the air right above the ground should be warmer than the layers above but cold enough to create snow – a very calculated and precisely natural prerequisite.

Things to do during a Nor’easter warning

– stock up with at least three days of food, water, and other provisions.

– thundersnow affects visibility, the roads become snow-covered or flooded – hence it’s best to remain indoors until the storm passes.

– keep in mind that electricity could be cut-off for a few days due to strong winds uprooting trees and disrupting power lines.