WORCESTER — Strong thunderstorms rolled through the city and county Friday evening, leaving power outages and downed trees in its wake.The National Weather Service earlier in the day issued a tornado warning for the region, but later downgraded its forecast to severe thunderstorms, which moved in from the west at dusk bringing powerful winds and heavy rain.Trees were knocked down across the region, from Hardwick to Westboro. National Grid reported more than 6,500 […]