Bill Appelbaum, a reader in Catonsville, thought he'd spotted a typo: "How can [the] wind chill index be 8 degrees lower than the air temperature if there's no wind?" It can't. But that's what our Thursday Weather Page said. So I called Weather Central, which provides our data. They discovered their computer coding was entering dewpoints (used with temperatures in summer to calculate heat index) as wind speeds. So Wednesday's 55-degree temperature and 51-degree dewpoint yielded a "wind chill" of 47 degrees. It's been fixed.