Hurricane Irma Bearing Down

Hurricane Irma Projected Path  (Source: NHC)

Hurricane Irma is already one for the record books as it approaches the U.S. mainland.  All of Florida is going to feel serious impacts from this storm.  High winds, deadly storm surge and flooding rains are coming.  Irma will make landfall in southern Florida this weekend as a strong Category 4 hurricane, after making landfall in Cuba last night as a Category 5 storm.

Some have compared Irma to Hurricane Andrew in 1992, since that was the last Category 5 hurricane to make landfall in the United States.  However, Irma is a much larger hurricane, and its sustained winds, heavy rainfall and storm surge will encompass a much larger area.  Hurricane Charley was the last Category 4 hurricane to make landfall in Florida in 2004.  Charley was more similar to Andrew than Irma since it was also a compact storm. 

Hurricane Irma has a much larger diameter – similar to Hurricane Katrina in 2005.  Irma is roughly the size of the state of Texas.  Obviously, Florida is not as wide as Texas so the entire state of Florida will feel significant impacts.  That means Hurricane Irma has the potential to do significantly more damage over a much larger area than Andrew did 25 years ago.  We have already seen some of Hurricane Irma’s destruction across parts of the northern Caribbean.

It’s useful to compare Irma to Hurricane Andrew since Andrew is Florida’s modern benchmark for devastating hurricanes.  The National Hurricane Center says Irma could intensify once it stops interacting with the island of Cuba.  Irma is expected to be a strong Category 4 hurricane as it approaches south Florida.  There isn’t much difference in the impacts an area will feel between a strong Category 4 hurricane and a Category 5.  Sustained winds in a Category 4 hurricane range from 130 mph – 156 mph, while a Category 5 has sustained winds of 157/+ mph. 

The sustained winds can be found around the “eye” or the center of the storm.  By comparison, the winds in an EF-3 tornado range from 136 – 165 mph.  Just imagine winds like that – with higher gusts – over a diameter of more than 50 miles from the center of Irma (many times larger than in a tornado).  Hence, the potential for wind damage in a hurricane – especially one of this side and intensity – is many times larger.  Another key point to make is that Hurricane Irma has been at Category 4/+ intensity for several days, so that combined with its large diameter will mean storm surge will be a significant issue. 

The only thing worse than being ill-prepared for a hurricane is to not evacuate in time and risk being caught on the highway when conditions deteriorate.  It’s vital that people continue to listen to their local authorities and meteorologists for instructions and the latest weather information.