(NewsNation) — As Hurricane Ian makes landfall in southwest Florida as an extremely dangerous Category 4 hurricane, there is concern over not just the high wind, rain and tornado threat it brings, but the life-threatening storm surge it conjures as well.

Storm surge is the abnormal rise of water over and above predicted tidal levels. It’s produced by water being pushed toward the shore by the force of the winds moving around a storm, according to the National Hurricane Center.

Hurricane Ian’s maximum sustained winds were around 155 mph at landfall, only 2 mph short of a Category 5 (157 mph). As a result, the National Hurricane Center is predicting Hurricane Ian will spur a catastrophic storm surge of 12 to 18 feet along the Florida coastline.

This rise in water level is expected to bring extreme flooding to the area.

“The power of water is just incredible,” NewsNation’s Gerard Jebaily said. “And with major hurricanes, what’s most concerning about them is storm surge.”

In a weak storm, you get a little bit to come ashore and it doesn’t really have as much of an effect, according to Jebaily. But the stronger the storm, the larger the possibility of a damaging storm surge.

Storm surges can severely damage marinas and boats and cause catastrophic flooding in low-lying areas. Fresh water reserves are also at risk of mixing with salt water as the storm surge rises, endangering public health.

A 15-foot storm surge was generated by Hurricane Floyd in 1999. Storm surge flooding of 25 to 28 feet above normal tide levels was associated with Hurricane Katrina in 2005. Katrina was one of the most devastating hurricanes in the history of the United States.

For some perspective, Hurricane Ian’s storm surge is predicted to be 3 times over the head of a human who stands 6 feet tall.

“And that’s a wall of water that does not include the waves,” Jebaily said. “That’s how huge we’re talking about.”

According to Jebaily, the water can rise 6 feet within a couple of hours.

“It may be a little bit deceptive at first because you don’t notice some things that are happening slowly, he said. “It’s not a tidal wave that rushes in, usually, but you can still see that water moving in a lot quicker. And it can cut off escape routes.”