Hurricane Harvey will likely wind up being the most expensive natural disaster in American history, costing the economy about $190 billion, according to AccuWeather.

In fact, the weather forecasting firm predicts it will wind up costing more than Katrina and Sandy combined.

"This is a natural disaster that was not fully calculated," Dr. Joel Myers, AccuWeather's founder and president, said in an interview with "Closing Bell" on Thursday.

"You had the greatest rainfall ever measured in the continental United States."