Florida Commission Accepts Three New Flood Models as Storm Impacts Rise

As with computer models that help predict risk from hurricane winds, insurers now have more than one model to use when gauging flood damage in storm-soaked Florida.

The Florida Commission on Hurricane Loss Projection Methodology this month accepted three flood models, one from Karen Clark & Co.; one from Aon’s Impact Forecasting; and a public model that was developed by teams from eight universities – including five Florida universities – along with AMI Risk Consultants and NOAA’s hurricane research team.

The models were approved just weeks after Hurricanes Helene and Milton brought widespread storm surge and inland flooding to Florida, resulting in more flood insurance claims than some in the industry had initially expected. Those two storms have so far resulted in more than 80,000 flood claims, including some 6,183 claims with private flood insurance companies, according to the Federal Emergency Management Agency and Neptune Flood Insurance.

The number of National Flood Insurance Program claims from Helene, now approaching 60,000, already is well ahead of the 48,700 NFIP claims seen after Hurricane Ian swamped southwest and central Florida in 2022.

Milton, which made landfall Oct. 9, brought surge and floodwaters that impacted some 185,000 buildings all across Florida – about 20,000 more than the number affected by Helene, said ICEYE, a satellite imagery analytics company. In Hillsborough County alone, some 74,000 structures saw some level of flooding in Milton, a number that was higher than expected because Milton’s eyewall just missed the populous Tampa area.

It’s unclear at this point if the new flood models would have better predicted where the flooding was worst in the recent storms. But the teams that produced the new models have said their software utilizes more data points and includes the impact of climate change and the new reality of frequent and heavy rainfall on low-lying terrain.

The Karen Clark model, available for most of the country, provides a high-resolution view of storm surge and inland flooding and includes a catalog of more than 100,000 flood-intensity footprints, along with thousands of items that affect vulnerability, including property features, such as building construction, height, first-floor elevation, type of basement, wet and dry floodproofing, and other secondary characteristics, KCC said in a statement.

Until now, Karen Clark’s flood modeling system was the only one accepted by the Florida methodology commission. Version 1 was approved in 2017 and has now undergone a major upgrade.

“Version 2.0 of the KCC US Flood Reference Model includes several enhancements, most notably the incorporation of the effects of climate change to date,” said Daniel Ward, KCC’s senior director of model development. “Climate change has led to an increase in both the frequency and severity of coastal flooding and inland flooding. The updated model also explicitly represents urban drainage systems, which is especially important for coastal cities like Miami and Tampa.”

The public model also examines more than just elevation and goes beyond some predictive models that have been around since the 1960s, explained Hugh Willoughby, a member of the commission and a professor at Florida International University. FIU researchers helped develop the new public model.

“One question now is, ‘is it rainfall or drainage that’s having the most impact,'” Willoughby told Insurance Journal this week.
Having more than one model has been considered important to some insurers, especially in wind-damage risk assessment. In 2023, the Florida Legislature changed state law to allow property insurers, when filing for rate increases, to use an average of two or more computer models approved by the commission. Until that law was enacted, insurance carriers in Florida had to choose from one of three models. That was an issue because models often differed by as much as 50% on loss projections, experts said.

The use of more projections is a good thing for insurers and insureds and should encourage the development of even more forecasting simulations, Willoughby said last year.

The Florida Commission on Hurricane Loss Projection Methodology now accepts windstorm modeling from at least six vendors, including Karen Clark, Impact Forecasting, and Florida International University.

It’s uncertain how the new flood models will impact flood coverage and premiums in Florida. Neptune Flood, one of the largest private flood insurance providers, does not utilize the modeling systems, the company said this week.

The KCC flood model presentation to the commission can be seen here. The Impact Forecasting model information is here. The public model info is here.

Top photo: Cover shot for Aon’s Impact Forecasting model presentation.