The agency sent investigators to the area Saturday make the determination.
The tornado, classified as an EF1, left a half-mile long path of damage concentrated in the Pine Rock Park area, according to the NWS report.
Dozens of trees and utility poles snapped during the storms Friday afternoon, damaging fifteen to twenty Shelton homes. A few roads still remained closed Saturday afternoon.
Pine Orchard Country Club in Branford canceled a golf tournament Saturday because two dozen trees littered the course.
The onslaught of rain is also causing Connecticut rivers to rise, so swimming in rivers is not advised, despite the break from the rain.
To see the National Weather Service's complete report on the Shelton tornado click here: