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Tornado-Like Phenomenon Spotted Off The Coast Of Manhattan

| July 21, 2018 @ 9:30 am

(Credit: Washington Post)

A cold front slid eastward on Tuesday, July 17th, spawning a line of strong to severe storms from northern New England to the Mid-Atlantic.

Most of the thunderstorms were embedded within an organized line, which made the storms less conducive to tornado development. However, what appeared to be some sort of rotation spawned just off the coast of Manhattan that afternoon. Video footage from several sources captured what appeared to be a funnel forming at the leading edge of the line of storms. 

What is odd about this funnel is that it formed at the leading edge of the storms. While this is not uncommon nor unheard of, rotation typically occurs in single supercell storms which often have plenty of open space to twist and form. Funnels that form at the head of thunderstorm lines are often more difficult to assess in the aftermath.

It was a hot and humid day ahead of the cold front on the East Coast, so as the cold front spread east there was plenty of warm air feeding into the storms from the south. This provides the storms with plenty of warm, moist air to keep energy flowing. As cold air descended from the north, the two opposing air masses had the possibility of creating what is known as “kinks in the line” or horizontal moving air that spins into a funnel cloud. This may not be the case for the New York City funnel cloud, but it may explain the reason Windham County, CT was issued a tornado warning around 4pm that day.

It was after 4pm that reports of a funnel cloud was spotted off the NYC coast, though it is unlikely that was caused by the same weather phenomena that warranted a tornado warning in Connecticut. Instead, it was likely that the funnel cloud was the result of a less threatening type of weather known simply as “scud”. Scud is the result of moist air being cooled and condensed into a nearby downdraft. Moist air feeding the thunderstorm gave people the idea that the rising air was forming a waterspout or tornado.

Several videos, however, dispute any claims of a waterspout. In the videos, the edges of the funnel are rough and jagged, unlike the smooth perimeter of waterspouts and tornadoes. The videos also show that air is rising into scud, while a tornado or waterspout would form from the cloud base downwards.

Thunderstorms were beginning to disintegrate at the time of the scud. Meteorologists noted that cloud top heights were dropping as they approached the coasts, indicating weakening storms and a burst of cool air ahead of the storms known as “outflow”. The opposing air flows, rising and sinking, could create an invisible horizontal vortex that could form a tornado. However, in some cases, structures near the ground can cut into the tube and create smaller vertical pieces of rising air. This is likely what caused scud instead of a waterspout in NYC earlier this week.

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©2018 Weather Forecaster Jacob Dolinger

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