It’s just over ten years to the day since Hurricane Ike made landfall near Galveston, Texas. Looking back at the 2008 North Atlantic hurricane season’s activity, it was above-average with 16 named storms, eight of which reached hurricane strength, and five became major hurricanes (Cat 3 or greater). Hurricane Ike did reach Category 4 over the warm waters of the open Atlantic, but later weakened as it tracked along the Cuban coastline, never to fully regain its strength. At around 0710 UTC on Saturday, September 13, 2008, Ike struck the Texas coastline as a strong Category 2 hurricane (on the Saffir-Simpson Hurricane Wind Scale), producing maximum sustained winds of 110 miles per hour (175 kilometers per hour).
It was by far the costliest event of that year, and today remains firmly in the top ten of most costly U.S. hurricanes. At the time, RMS loss estimates were in the range of US$13 to US$21 billion, excluding NFIP (flood) losses. Ike was blamed for at least 195 deaths, as it ravaged the Bahamas, Haiti, Cuba, and onward to the U.S. Ike did not make the history books for its wind speeds, it did not have the destructive wind intensity of more recent events such as Hurricanes Irma and Maria. It was the sheer geographic extent and inland penetration of Ike that makes it stand apart from most other hurricanes.
Largest Wind Field
Hurricane force winds from Ike extended up to 125 miles (195 kilometers) from the storm center, affecting the Texas coastline between Freeport and Port Arthur (as of 0700 UTC). At one point, on its approach to Texas, Ike’s wind field spanned 600 miles (965 kilometers) across, which is very large — in comparison to Hurricane Katrina, also considered a very large storm, which had a maximum wind field span of 440 miles (708 kilometers). After landfall, Ike was fuelled by a strong combination of kinetic energy and inertia allowing the storm to extend its winds hundreds of miles inland. Ike reached the state of Arkansas, some 350 miles northeast of Galveston, the following day on Sunday, September 14, before weakening and beginning a process called “extra-tropical transition”.
But that was not the end of Ike. Later that day, the remnants of the storm merged with a frontal boundary across the lower Ohio Valley. The presence of a deep low-pressure area generated a tight pressure gradient to the south and east of the Ike’s remnants as it tracked into northwest Ohio through Sunday evening. This convergence of low pressure systems resulted in strong winds with gusts in excess of 70 miles per hour over a large area across the Ohio Valley, persisting for several hours. This is uncharacteristic of typical severe thunderstorm events. While the strongest post-transition winds were recorded in Ohio, the effects of Ike’s remnants also spread across Arkansas, Illinois, Indiana, Kentucky, Missouri, Ohio and Pennsylvania. Ike’s influence inland was significant and reminds us of the importance of following the risk from hurricanes through their full life cycle.
Some unofficial wind observations show the highest gusts of 84 miles per hour (135 kilometers per hour) occurring in West Chester, Ohio. Official observations measured up to 75 miles per hour at the John Glenn Columbus International Airport — making it the strongest gust to ever be recorded at this location and the second highest gust to be recorded in the area. Gusts in excess of 60 miles per hour were recorded widely throughout Ohio with the Cincinnati, Columbus and Dayton metro areas experiencing the strongest winds. Still today, Hurricane Ike caused more insured loss in Ohio than any other wind event in the historical record.
Storm surge was also a major factor. For a category 2 event, the storm surge generated by Ike was not only higher — with gauge data showing water levels reaching about 9 to 12 feet above normal as Ike approached the Galveston coast – but also over a larger than usual area affecting a very long expanse of the coastline, extending 310 miles along the shore of northwestern Gulf of Mexico.
And Then There Was the Rain
And to complete this “triple-threat” alongside damaging winds and storm surge, torrential rains due to Hurricane Ike were not only observed at landfall in Texas and Louisiana, where it was reported that local rain amounts exceeded twenty inches (500 millimeters), but also far north in Illinois and Indiana. Rainfall of six to nine inches caused significant flooding that was already underway due to a rain front. Chicago observed a new 24-hour rainfall record when Ike caused 6.6 inches on September 13, 2008.
On Saturday, September 14, 24-hour rain thresholds with local return periods of 100 years were exceeded in Michigan and Missouri; sustained, major flooding occurred in areas such as St. Louis.
It continued, as record breaking rainfall was also observed in Canada where the remnants of Ike got completely absorbed by a frontal boundary. In Windsor, Ontario, the previous rainfall record was exceeded by three inches on September 14, 2008.
Around 700,000 assistance claims were made to FEMA, the Texas Windstorm Insurance Association received more than 76,000 claims, 54 offshore oil and gas platforms in the Gulf of Mexico were destroyed. Power outages ranged from Texas, through to Ohio and into Ontario, Canada. Texas saw up to 4.5 million customers without power.
Two points really stand out from Ike. A common misconception is that hurricanes affect only coastal regions with wind and storm surge, but Ike was an example of how some hurricanes can produce significant risk well inland, and from both sub-perils of wind and flood. The risk of extra-tropical transitioning has the potential to deliver tropical storm winds to areas unfamiliar and unprepared for such events.
The second point relates to inland flooding, with torrential rains similar to Hurricane Harvey in 2017, affecting Texas and Louisiana, but also for Ike, far north in areas such as Ohio and Michigan, and even into Canada. Only through modeling tropical cyclones in a comprehensive way – including wind, associated storm surge and rain-induced inland flooding, can one get the complete picture of hurricane risk.