As of the National Hurricane Center’s 5 a.m. advisory on Sept. 8, Hurricane Irma has been ‘downgraded’ to category four status. This does not diminish the threat to life and property that this powerful storm poses.
The latest forecast takes the storm up the center of Florida. Hurricane force winds will affect most of the state, with the most severe impacts in the southern part, including the population centers of Miami and Fort Lauderdale.
Wind damage will be extreme in places that experience the eye wall, in which winds will exceed 150 miles per hour.
The Hurricane Center has also issued a storm surge warning for coastal areas of south Florida from Jupiter Inlet to Bonita Springs. Most loss of life in hurricanes is from inundation, particularly from storm surge, which is, in simple terms, a very high tide.
Three factors contribute to the rising water of a storm surge. First, the low pressure in a hurricane allows the surface of the water to rise. With less of the atmosphere pushing down, the water level in a severe hurricane rises about a foot above its normal level.
Second, the wind physically pushes the water towards the shore. This accounts for the majority of the surge, with water rising as much as 20 feet.
Third, breaking waves on top of the increased water level push the water farther inland.
The storm surge is greatest at time of high tide, but this is less of a factor in Florida than further north, since tidal range increases with latitude. In Boston, the range is about ten feet and in Nova Scotia can be up to 30 feet. But in southern Florida, the tidal range is less than three feet. Though the risk of storm surge is greatest at the time of high tide, which this weekend will be around noon and midnight in Miami, flooding due to rising ocean water could occur at any time where 150 mile per hour winds push the water and whip the waves.
Hurricane Irma Evacuation
Hurricane Irma’s path is the worst possible as far as getting people out of harm’s way is concerned. Irma will be traversing Florida from south to north. The best way to flee a hurricane is to travel perpendicular to its path, but that would mean east or west to escape Irma, and this would be impossible for anyone without an amphibious vehicle.
Escape to the north is the only option and there are only so many roads.
Since Irma will still be a hurricane in northern Florida, residents of south Florida will have to travel many hundreds of miles to be safe.
Cuba May Help — A Little
The latest forecast track has Irma’s eye moving close to the coast of Cuba. Mountains are to hurricanes as kryptonite is to Superman, so the circulation of Irma could be somewhat disrupted by the high terrain of Cuba. But even in the best scenario, this would only diminish Irma’s strength a little. South Florida is virtually certain to take a major hit.
Don’t Be A Hero
It may be tempting to ride out any storm. If you are in the path of this hurricane, don’t do it. The wind will be very strong and the water can rise very fast.