A storm surge is an abnormal rise in sea level caused by a storm.
Tropical cyclones such as hurricanes do not just bring strong winds and heavy rain. Often it is the storm surge that produces the most damage and threat to life through extensive coastal flooding.
Tropical cyclones form at sea fuelled by warm water. Strong winds develop as air begins to circulate. Water is pushed in the direction in which the winds are blowing, causing the water levels to rise.
This is not particularly noticeable in deep sea but as the ocean floor becomes shallower close to land, the wall of water has to rise and is driven onshore by strong winds.
Storm surges are worse at high tide and other factors contribute to the water level too, such as the direction of approach, size and speed of the storm, central pressure and topography of the coastline.
For Hurricane Milton, as it approaches land from the west, it will be the southern side of the eye where the largest storm surge will be.
The hurricane-force westerly winds will be pushing water inland.
To the north of the eye, easterly winds will temporarily push water away from the coast
From Tampa Bay to Boca Grande, up to 15ft (4.5m) of coastal inundation is expected but should the track come a little further south, the most extreme surge scenario for Tampa Bay might be avoided.
Regardless, the storm surge is still likely to be catastrophic and exceed the record 7.8ft (2.4m) height seen during Hurricane Helene.