Beware the “I” Storms

Hurricane Ike, 2008  (Source: NOAA)

Tropical Storm Isaias was named July 29 and became the earliest “I” storm on record in the Atlantic Ocean Basin.  It was the fifth named storm this month, which tied July 2005 for busiest on record.  Last night it was upgraded to hurricane status and became the second Atlantic hurricane of 2020.  The United States has felt the impacts of some significant “I” storms during the last 20 years.  In fact, the “I” storm has been retired nine times since 2001!

2011: Irene was the first major hurricane of 2011, peaking as a Category 3 with sustained winds of 120 mph.  However, Irene weakened to Category 1 status before its first landfall in North Carolina.  Its impacts were far reaching from the Mid-Atlantic to New England.  According to the National Hurricane Center, Irene remains the fourteenth costliest hurricane on record in the United States ($13.5 billion in damage - adjusted for inflation).

2008:  Ike was a Category 4 hurricane with sustained winds of 145 mph and a minimum air pressure of 935 millibars (mb).  By comparison, standard sea level air pressure is approximately 1013 mb.  Fortunately, it weakened to a strong Category 2 storm with sustained winds of 110 mph by the time it made landfall in Texas.  Since Ike had a very large diameter and traveled across the entire Gulf of Mexico, it was able to build up a very impressive storm surge when it made landfall.  It did approximately $30 billion in damage at the time, making it the sixth costliest hurricane on record.   

2004: Hurricane Ivan was the strongest hurricane of a busier-than-average hurricane season.  It was a Category 5 storm that caused significant damage to Jamaica, the Dominican Republic and the Cayman Islands.  It remains one of the strongest hurricanes to form in the Atlantic Ocean.  At peak intensity Hurricane Ivan’s lowest air pressure was 910 millibars and highest sustained winds around the center of the storm were 165 mph.  Air pressure is considered a more accurate measure of hurricane intensity than wind speed.

Fortunately, Ivan weakened to Category 3 intensity before it made landfall in Alabama on September 16.  Nevertheless, it caused nearly $20.5 billion in damage at the time.  That made Ivan the 10th costliest U.S. hurricane on record.  Ivan is also significant since it set a record for spawning more tornadoes in the United States than any other tropical storm or hurricane.

2003: Isabel was the first Category 5 hurricane in the Atlantic Ocean since 1998.  Hurricane Isabel reached its peak intensity on September 11, with maximum sustained winds of 165 mph combined with a minimum central air pressure of 915 millibars.  Isabel weakened to Category 2 intensity with sustained winds of 105 mph before making landfall in North Carolina on September 18.  Despite weakening, Isabel caused major flooding and damage across much of the Mid-Atlantic Region and Northeastern United States.  In the DC Metro Area, Isabel caused approximately one million power outages.  In all, Isabel caused about $5.5 billion in damages in 2003.