The National Weather Service confirmed that a tornado touched down in Holden, Massachusetts, on Saturday afternoon.

The tornado was radar confirmed around 4:07 p.m. It appears as though it was only on the ground for a short period of time before lifting. "Radar confirmation" means that while it wasn't observed by the naked eye, there was enough evidence on radar to confirm the existence of a tornado.

Storm damage on Twinbrooke Drive in Holden. Steve Karsok

Forecasters also use something called the correlation coefficient, a method of radar that can detect when debris is tossed into the air from a tornado touchdown.

Weather graphic. CBS Boston

A velocity scan on radar also showed the tightening of winds, which is what prompted the National Weather Service to issue a tornado warni

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