An overestimated hurricane

Back in December, I speculated that five or six hurricanes from 2005 would get their names retired, easily besting the record of four set in 2004. Certainly, Katrina, Dennis, Emily, Wilma, and Stan will have their names retired, but what about Ophelia? The December preliminary report on Ophelia put her damage at $1.6 billion, perhaps high enough to get her name retired. Well, the National Hurricane Center has released its final report for Hurricane Ophelia, which brushed North Carolina as a Category 1 hurricane on September 14-15, 2005. It turns out that damage estimates and the estimated height of the storm surge were both considerably overestimated at the time of the storm. The Insurance Information Institute put out a preliminary estimate of $800 million in insured damage for Ophelia, which translated into a total damage estimate of $1.6 billion, based on the rough rule of thumb that total damage is double the insured damage. However, the final damage reports for Ophelia only added up to $35 million in insured damage ($70 million total damage), making it very unlikely that Ophelia will get her name retired. The $1.6 billion damage estimate was based on a model used by the insurance company. Considering that the model was off by a factor of over 20, I think we can take future preliminary damage estimates from hurricanes with a healthy dose of scepticism!

Initial storm surge heights were also considerably off, which likely let to a good part of the error in the damage estimates. If you go back to my blog from September 15, 2005, I reported: "storm surge values ranged as high as 10 - 12 feet in some of the smaller creeks in the Neuse River near New Bern, a remarkably high storm surge for what was a tropical storm for that area." This information was based on Local Hurricane Statements released by the National Weather Service at the time of the storm. I prepared a map(Fig. 1) showing the estimated storm surge from these Local Hurricane Statements. However, the NHC official storm report lists maximum storm surge height of only 4-6 feet, about half of what was reported at the time of the storm. Again, we need to be sceptical of preliminary data from hurricane landfalls.


Figure 1. Storm Surge heights measured in Ophelia.

Jeff Masters