Tropics Getting Active

 

Not a coincidence that the tropics have gotten quite active the last few days with mid-September being the climatological peak of the Atlantic hurricane season.  Tropical Storm Sally is expected to become a minimal hurricane before it makes landfall along the US Gulf Coast, while Paulette has impacted Bermuda as a borderline Category 1/Category 2 hurricane.  It’s a good time to remember some significant September hurricanes that have battered the United States.

Florence (2018) – At peak intensity, Florence was a powerful Category 4 hurricane over the open Atlantic with sustained winds of 150 mph and minimum central air pressure of 937 millibars (mb).  Standard sea level air pressure is approximately 1013.25 mb.  Fortunately, Florence weakened as it approached the North Carolina coast where it made landfall September 14 as a Category 1 hurricane. 

However, because its forward speed had slowed dramatically it brought significant flooding rainfall to areas well-inland, even after it was no longer a hurricane or tropical storm.  Meteorologists compared the flooding from Florence as similar to what Hurricane Harvey brought Texas in 2017.  The DC Metro Area saw record rainfall and flooding from the remnants of Hurricane Florence on September 17-18, 2018.

Irma (2017) – Irma was the first of two Category 5 hurricanes (Maria) of the destructive and deadly 2017 Atlantic hurricane season.  At peak intensity, Irma had sustained winds of 180 mph and a minimum central air pressure of 914 mb.  Hurricane Irma was also at Category 5 intensity for three consecutive days - a new Atlantic record.  Irma was the first Category 4 hurricane to make landfall in Florida since Charley in 2004, and Florida’s first major hurricane since Wilma in 2005. 

Ivan (2004) – The strongest hurricane of the active 2004 season, Ivan was another Category 5 hurricane with peak sustained winds of 165 mph and a minimum central air pressure of 910 mb.  Hurricane Ivan weakened to Category 3 status before its landfall near Pensacola, Florida.  It caused a significant amount of damage not only where it made landfall, but in areas well inland as well.  Ivan set a new record for spawning the highest number of tornadoes in the United States.  Its remnants brought severe weather to the DC Metro Area on September 17, 2004.

Isabel (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 mb.  Fortunately, 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 and the Northeast.  In the DC Metro Area, Isabel caused approximately one million power outages.