The National Weather Service has issued a tornado watch for much of New York State, including St. Lawrence County.
A severe thunderstorm warning is also in effect.
Trees and power lines are down across the county because of the storm.
The tornado watch indicates severe weather conditions which create opportunities for tornadoes to form. A high wind advisory for the county warns of steady winds up to 30 miles per hour, with brief gusts approaching 50 miles per hour.
The tornado watch ends at 10 p.m. Saturday.