Irma Becomes a Rare Category 5 Hurricane

Category 5 Hurricane Irma  (Source: NOAA)

Hurricane Irma has became a rare Category 5 hurricane with sustained winds of 185 mph.  That makes it the strongest Atlantic hurricane since Hurricane Wilma in 2005 which also had sustained winds of 185 mph.  The latest forecast from the National Hurricane Center brings Irma close to the United States.  There is a great deal of uncertainty with the track of every hurricane but past Cape Verde hurricanes can provide us with some insight as to where Irma could track. 

Two Category 4 hurricanes made landfall in south Florida in 1926 and 1928, respectively, and had devastating impacts.  These hurricanes occurred before hurricanes were named so they’re commonly referred to as the “1926 Miami” and “1928 Okeechobee” hurricanes.  Hurricane Donna made landfall in the Florida Keys as a Category 4 hurricane on September 10, 1960 and subsequently impacted much of the U.S. east coast.  Based on air pressure at the time of landfall, these three hurricanes rank among the ten strongest on record to make landfall in the United States.  

There are also some similarities between Hurricane Irma and Hurricane David in 1979.  David was at one point a Category 5 hurricane and impacted much of the northern Caribbean.  It was considerably weaker before it tracked up the east coast of Florida and impacted the eastern United States.

Other Cape Verde hurricanes have impacted the Mid-Atlantic and Northeastern United States.  The “Long Island hurricane of 1938” made two landfalls as a Category 3 hurricane.  One was on eastern Long Island and the second was in Connecticut.  Fortunately, eastern Long Island was sparsely populated at this point in history so a similar storm would likely be much more damaging if it were to occur in modern times.  Hurricane Andrew remains the last Category 5 hurricane to make landfall in the United States when it came ashore south of Miami in 1992.

Many longtime Washingtonians remember Hurricane Isabel in September 2003.  Once a Category 5 monster, Isabel weakened to a Category 2 storm before it made landfall in North Carolina.  Isabel caused widespread power outages in the DC Metro Area and flooding along the Chesapeake Bay and Tidal Potomac.  By comparison, Hurricane Earl was a powerful Category 4 hurricane in 2010 that recurved and did not make landfall in the United States.  

Many things such as large or “synoptic” scale weather systems like areas of high pressure can influence the track of a hurricane.  More localized things such as sea surface temperatures or wind shear can also influence hurricane track and intensity.  Hurricane forecasting has improved dramatically in recent years but a high degree of inherent uncertainty will always remain due to the high number of variables involved in tropical systems.  

The only thing we know with certainty right now is that Hurricane Irma is a dangerous Category 5 hurricane that deserves our full attention.  It’s vital that people in Florida and the eastern United States pay attention to their favorite meteorologists and local authorities.  The National Hurricane Center will continue to provide the latest information on Irma’s intensity and expected track.