The federal government’s flood maps, which are used nationwide to signal areas vulnerable to inundation, vastly underestimated the flood risk faced by properties in the parts of North Carolina devastated by Hurricane Helene, according to data analyzed by The Washington Post.The analysis of flood risk data from First Street, a climate modeling group, found that just 2 percent of properties in the mountainous counties of western North Carolina fall inside areas marked as having a special risk of flooding. That “Special Flood Hazard Area” designation, which compels homeowners to buy flood insurance if they want to get a federally-backed mortgage,...