Real estate analytics firm CoreLogic has been issuing an annual report on coastal flood risk since 2011. This year, the company says, there are more than 6.5 million homes exposed to a possible hurricane storm surge along the Atlantic Ocean and Gulf of Mexico coastlines. In dollar terms, that amounts to more than $1.5 trillion of value — with more than $986 billion of that concentrated in just 15 major metropolitan areas.

In reality, of course, a trillion-and-a-half-dollars worth of housing value will never get wiped out by hurricanes in any one year, or even in a hundred years. In 2005, for example, the most active Atlantic hurricane season on record (which included the catastrophic Hurricane Katrina), storm damage from the seven major hurricanes that hit the U.S. amounted to $159.2 billion — and that total includes all of the destruction, not just the damage to houses.

But the numbers do give a sense of how much value is concentrated along the nation's coastline. And CoreLogic's closer look at the risk to particular states and cities helps to put the risks in perspective.

This year, CoreLogic is gauging the potential damage from storm flooding based on the estimated reconstruction cost of properties at risk, derived from data supplied by Marshall & Swift/Boeckh (MSB), a firm that CoreLogic acquired this spring. "Reconstruction cost estimates are a more accurate reflection of the actual cost of repairing or replacing residential buildings that could be damaged or destroyed due to hurricane-driven storm surge since they include the cost of materials and labor, and also factor in geographical pricing differences," the CoreLogic report says.

Florida tops the list of states in terms of number of properties at risk (2,488,277), and also in terms of their potential reconstruction cost ($490,403,653,377), the report says. But at the scale of a metropolitan area, New York ranks first, with 687,412 properties exposed to flood and $251,038,846,466 at stake. (Miami, Florida, comes in second among the cities.)

Not all of the houses at risk for flood fall withing a FEMA-designated flood plain, CoreLogic points out. FEMA's in-or-out floodplain definition, CoreLogic argues, obscures the true nature of flood risk, and discourages some homeowners from buying flood insurance even though there's a chance they might need it.

The CoreLogic report is available at CoreLogic's website, here (CoreLogic Storm Surge Report)