A Severe Thunderstorm Watch has been issued for a large portion of the Northeast. It was issued just before noontime and is in effect until 8 p.m. Wednesday, July 21. Damaging wind gusts and large hail are the main threat, the National Weather Service said in issuing the watch. "We're already beginning to see storms develop and move into the area," the National Weather Service said at 12:10 p.m. Torrential downpours, frequent lightning, and flash flooding are all possible.