Laura arrived as a category 4 hurricane in Louisiana on Thursday, U.S. weather officials said. The National Hurricane Center is warning that the “combination of a dangerous storm surge” from Hurricane Laura and the tide “will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline.” The water could reach as high as 15-20 feet from Louisiana’s Johnson Bayou to the Rockefeller Wildlife Refuge, including Calcasieu Lake, the center said. It added that an “unsurvivable storm surge with large and destructive waves will cause catastrophic damage from Sea Rim State Park, Texas, to Intracoastal City, Louisiana, including Calcasieu and Sabine Lakes. This surge could penetrate up to 40 miles inland from the immediate coastline, and flood waters will not fully recede for several days after the storm.” Laura smashed across the Louisiana coast as a Category 4 hurricane early Thursday. The system maintained hurricane strength for about 11 hours before being downgraded to a tropical storm. The Miami-based center said the storm system is expected to continue moving over Arkansas in the night and then on into the mid-Mississippi Valley on Friday before reaching the mid-Atlantic States on Saturday. It says the system will dump heavy rains in spots, raising the risk of flash floods.