BALTIMORE—Warning that the storm could batter the East Coast with 80-mile-per-hour winds and heavy rain, Baltimore officials confirmed Friday that residents were preparing for Hurricane Joaquin by adding a second layer of plywood to the city’s shuttered small businesses. “A tropical storm as severe as this can cause considerable damage, so we’re urging residents to take precautionary measures by covering boarded-up windows and doors of vacant storefronts with an additional protective layer of plywood or plastic sheeting,” said city spokesman Jim D’Amico, adding that extra tarps should also be placed over the ones already covering any furniture or other large items that went unclaimed by creditors.