Co-authors: Michael Kozar, Senior Modeler, RMS HWind; James Cosgrove, Senior Analyst, RMS Event Response
Michael underwent rapid intensification in the two days leading up to landfall, reaching the Florida Panhandle coastline as a strong Category 4 major hurricane with maximum sustained wind speeds of 154 miles per hour (247 kilometers per hour), according to the RMS HWind real time service. At landfall, Michael had a tight inner core and its strongest winds were located just 14 miles (22 kilometers) south-southeast of the center of the storm near Mexico Beach. Tropical storm force winds extended up to 115 miles (185 kilometers) eastward along the Panhandle coastline to Pensacola.
Whilst the Saffir-Simpson Hurricane Wind Scale (SSHWS) is exclusively based on maximum sustained wind speeds, which often only covers a very small part of the system, the Integrated Kinetic Energy (IKE) metric conveys the intensity, size, and structure of the storm’s wind field into one number and has become a useful metric for comparing the destructiveness of storms. Using the IKE metric, we can compare and contrast Hurricane Michael to other events in the RMS HWind historic archive.
Hurricane Michael’s IKE measured 25 Terajoules (TJ) at landfall. Somewhat surprisingly, this is almost half of Florence’s IKE value (49 TJ) when it made landfall near Wrightsville Beach, North Carolina, in mid-September. Although Florence was a weaker storm — a Category 1 hurricane with maximum sustained wind speeds at landfall of 93 miles per hour (149 kilometers per hour) — the system was much broader. Michael’s energy, meanwhile, was focused in its destructive core — a core that was responsible for the extensive damage seen in the communities near landfall, such as Mexico Beach and Panama City.
Michael set many numerous meteorological records during its short lifetime, becoming the strongest hurricane (by wind speed) to make landfall in the continental U.S. since Andrew in 1992, and the strongest (by wind speed) October landfall in the continental U.S. on record. But how does it compare to other notable hurricanes that made landfall in the eastern Gulf of Mexico?
In terms of overall size, Michael does not measure up to some of the larger hurricanes that have recently impacted the region. Both Katrina (105 TJ; 2005) and Ivan (78 TJ; 2004) had very large inner cores and significantly more IKE than Michael, despite this season’s storm being more intense. That said, Hurricane Michael was not a small storm either, as it contained more IKE than the similarly intense Hurricane Charley (7 TJ; 2004), which made landfall on the west coast of the Florida Peninsula as a very compact hurricane.
Hurricane Dennis in 2005, which like Michael also made landfall on the Florida Panhandle, offers another interesting comparison point. Dennis had a small inner core that was marginally weaker than both Michael and Charley, but tropical storm-force winds extended over a much broader area resulting in a slightly larger landfall IKE value of 40 TJ, when compared to Michael.
The most recent hurricane to make landfall in the Florida Panhandle was Hermine in 2016, which made landfall just east of St. Marks as a Category 1 hurricane in the sparsely populated Big Bend region. Hermine was a minimal hurricane at landfall with maximum sustained wind speeds of 79 miles per hour (127 kilometers per hour) and an IKE of just 9 TJ.
Hurricane Irma also affected northern Florida but had been over land for several hours prior and had weakened substantially by the point it reached the region. Nonetheless, Irma maintained an expansive wind field as it weakened, with a large pocket of tropical storm force winds along the Atlantic coastline. As such, Irma still had more than 50 TJs of IKE when it moved into northern Florida, causing coastal flooding in and around the Jacksonville area.