What is a storm surge and what is the threat from Hurricane Idalia?

Storm surges often pose the greatest threat to life and property when powerful storms like Idalia hit - here's what you need to know about what it means

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As Hurricane Idalia hits Florida and Georgia it is unleashing powerful winds and torrential rains but it is storm surges that often pose the greatest threat to life and property when such storms strike, the National Hurricane Center has said.

With Hurricane Idalia the ocean water pouring onto land could be up to 15ft (4.6 meters) along parts of Florida's west coast, the NHC projected in its briefing on Tuesday. Farther south, up to 7ft of storm surge is expected in the Tampa Bay area.