Post-Hurricane Analysis

 

Hurricane Michael, October 2018  (Source: NOAA)

NOAA scientists study hurricanes for months and sometimes years after the final advisory has been written on them.  Each tropical storm and hurricane often serves as a model with lessons learned for forecasting and emergency preparedness.  Every once in a while a hurricane’s intensity at landfall is updated after the fact to reflect the research done by NOAA.

2019: On this date two years ago, NOAA determined Hurricane Michael was indeed a Category 5 hurricane at its time of landfall on the U.S. Gulf Coast in October 2018.  Originally, it was thought to be an upper end Category 4 hurricane, just below 5 status with sustained winds of 155 mph.  However, according to NOAA’s post-analysis Michael had sustained winds of 160 mph.  While there is little tangible difference between these wind speeds in terms of damage, reclassifying Michael as Category 5 changes a host of historical records.

The upgraded Michael became only the fourth Category 5 hurricane to ever make landfall in the United States and the first since Andrew in 1992.  (The two other Category 5 hurricanes to make landfall are Camille (1969) and the unnamed Florida Keys 1935 hurricane).  While Michael’s sustained winds were the lowest of the three other hurricanes, its minimum central air pressure of 919 millibars was the third lowest air pressure for a hurricane at its time of landfall.  Overall, Category 5 hurricanes are exceedingly rare since they require ideal environmental conditions to develop.

2002: For the 10^th anniversary of Hurricane Andrew, NOAA determined it was actually a Category 5 hurricane when it made landfall in south Florida.  Originally, it was ranked as a Category 4 hurricane with sustained winds of 145 mph on August 24, 1992.  Years of post-analysis study led scientists to reclassify Hurricane Andrew as a Category 5 with sustained winds of 165 mph.

Andrew had the infamous distinction for more than a decade of being the costliest natural disaster in U.S. history.  More recent hurricanes like Katrina, Harvey and Irma have each caused more damage than Andrew, but it still ranks among the Top 10. 

Little did people realize it at the time, but Andrew occurred three short years before a more active cycle began in the tropical Atlantic.  From the 1970s through the early 1990s, the tropical Atlantic was relatively quiet with below average tropical activity.  However, there has been a series of active Atlantic seasons since 1995.  That’s why listening to the latest forecasts from NOAA’s National Hurricane Center and your favorite local meteorologists is of critical importance.