The squall, spotted about 9:45 p.m. near Northport, was expected to hit Port Jefferson Station, Middle Island, Calverton and East Moriches areas before dissipating by 10:20 p.m., meteorologists at the Upton-based service said.
"We know it produced snow, sleet, hail and graupel," which are raindrops coated with ice, meteorologist Pat Maloit said shortly after the squall broke up.
He said the service was waiting for reports on snow accumulation.
A snow squall is a sudden and intense weather system that brings moderate to heavy snowfall and often gusty winds.
The one over Suffolk formed when energy in the midlevels of the atmosphere acted on local instability in weather patterns, Maloit said. "Once that energy moved by, it no longer had its support, so it [the squall] dissipated," he said.
The service had warned visibility could be reduced to less than half a mile and that a few rumbles of thunder might be heard.
People in the Northport and Commack area reported hearing a loud "boom" to officers in the Second Precinct Tuesday evening, said Suffolk police, who attributed the sound to the squall.
Maloit said thunder that occurs low enough in the atmosphere can be very loud and can set off car alarms.