This story has previously been published related to other hurricanes’ threat of storm surge. It has been updated to reflect conditions with Laura.

(CNN)When Hurricane Laura makes landfall, the major storm will bring with it flash flooding, extreme winds and unsurvivable storm surge, the National Hurricane Center said Wednesday.

Almost half of all deaths from tropical cyclones come from storm surge. While many people focus on the wind speed of storms, the danger often comes from the water flowing in from the ocean. Follow live Laura updatesPrivately, you may be wondering (and you wouldn’t be alone): “What exactly is storm surge?”Read More”A storm surge is a rise in water level caused by a strong storm’s wind pushing water on-shore,” said CNN meteorologist Brandon Miller. “The wind literally piles up the ocean water and pushes it on the land.” Storm surge from Laura could reach 30 miles inlandGeography, tide cycle and wind direction are all factors in how severe storm surge could be, Miller said. The stronger the storm, the stronger the winds and the higher the storm surge will be. Laura is predicted to come ashore as a Category 4 hurricane.National Hurricane Center forecasters warned of “life-threatening storm surge and hurricane-force winds” for parts of the Gulf Coast.Storm surge warnings — issued when there is a danger of life-threatening inundation for the next 36 hours — have been issued from Freeport, Texas, to the mouth of the Mississippi River.Follow Laura’s path here“The topography in south Louisiana is extremely low-lying, so water can travel very far north with a storm like Laura,” CNN meteorologist Jennifer Gray says. “It’s made up of lots of marshland, as well as a network of lakes and rivers that feed into the Gulf of Mexico.”Laura will push all of this water very far north — up to 30 miles inland — quite possibly reaching Interstate 10.”Every little bayou, every little river that normally drains your rain, is going to flow in the opposite direction with storm surge,” National Hurricane Director Ken Graham told CNN. Even for a city as far away as New Orleans, the metro area is forecast to have a storm surge between 2 and 4 feet.Laura will likely hit parts of Louisiana right at high tide. All that water has nowhere to goStorm surge also can exacerbate flooding. As the water piles up along the coast, rivers and streams that typically drain into the ocean can become clogged farther upstream, forcing water levels to rise.That water doesn’t just leave. Depending on how much water was pushed ashore and the area’s watershed, it may hang around, causing further damage to communities.Due to climate change, storm surge has become an even greater threat in recent years. “Sea levels have risen in most places by about 1 foot over the past century. The higher baseline ocean level allows storm surges to reach even higher, increasing their destructive capabilities,” Miller said. The National Weather Service in a 2014 report said that most surge deaths occurred in Hurricane Katrina and several other big, powerful storms. In a majority of storms, excessive rainfall that leads to drownings is the leading cause of death.

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