Jeff Masters, director of the Weather Underground forecasting service, said Thursday that the biggest threat to Mar-a-Lago won't be Irma's winds, which could top 140 mph when it reaches Palm Beach. Instead, it will be storm surge, which he said could reach eight feet in a worst-case scenario. An interactive map by Climate Central shows that a more likely six-foot sea rise would put some of the property's low-lying areas at peril. An eight-foot surge could cause some water damage to the main buildings.