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Flood Maps, Storm Surge Maps Change

May 31, 2017

Hurricane season is here and you're probably hearing a lot of talk about maps; storm surge maps and perhaps even flood zone maps. Here are some clear differences to help you understand what they mean for you.

Let's start with storm surge maps. They help emergency managers make plans to protect the nearly 21 million people who call Florida home -- by predicting how high the water wall forced onshore by a storm might be and how far inland it will invade. That will also help you know when it's time to head for higher ground. 

And this year, storm surge maps are new. Chris Zambito is the chair of the Florida Floodplain Managers Association.

He said Florida used to have 11 distinct "SLOSH" (sea, lake and overland surges from hurricanes) models.  That's a model specifically for hurricane planning:  Tampa, Miami, the Panhandle, they all had their own. So the state and the National Hurricane Center worked together to create a "super basin."

“When you have any of these mapping studies, for the FEMA mapping or hurricane planning you have these seams, where one study was done and another study was done. So there are inconsistencies right at the border.  So, by doing a "super basin" of Florida, they kind of have the whole peninsula of Florida mapped,” Zambito said.

So here's how he says it might play out on evacuation maps in Hillsborough County, for example:

“You're gonna see, red, yellow, green, blue and it's gonna go push a certain extent inland. So, what I'm saying from at least the few maps I've looked at , that extent inland hasn't changed dramatically, what I am saying is the depth of water shown to be in those zones is going up,” he said.

Right now, emergency managers across the state are adding this new information into their plans. But Pinellas County Floodplain coordinator Lisa Foster says if you hear there are changes to evacuation zones in your neighborhood, stay up on it.

Foster said, “Living in Florida comes with its risks, especially if you're on the coast, close to a river, close to a pond, or even in a highly developed urban area, you just need to be aware.”

That goes for tourists, too. Make a plan if your hotel is in an evacuation zone. 

Then there are flood zone maps, which are updated as flood risks change---because of development, erosion or other factors. FEMA uses them to determine whether you have to carry flood insurance, and just how much you'll pay if you choose to go with the National Flood Insurance Program.  That’s voluntary, unless you have a federally-backed mortgage and are in a special flood zone. 

Right now, there are only about 1-point-8 million flood insurance policies in effect in Florida.

Flood insurance rates under the national program are surging now, because it was pushed deeply into the red by payouts for Hurricanes Katrina and Rita in 2005 and more recently, Superstorm Sandy.

FEMA's Susan Wilson says congressional changes in the last several years (under the Biggert-Waters Act) will now force owners of properties that had subsidized flood insurance rates to eventually pay full freight. 

Wilson said, “Their policies are being increased at a gradual rate, so that eventually they will become actuarial or risk-rated.”

And she said it's important to remember that flood insurance is a separate policy from homeowner's insurance.

While hurricane season is the time of year people talk most about the risk for flooding, Pinellas County Floodplain manager Foster says it isn't tied to a season. 

“Anywhere  it rains it can flood, a tree could fall and block a pipe, there could be nowhere for the water to go, you could get a storm surge. There are multiple things that could happen, I mean, it's the risk you take to live in Florida,” Foster said.

And flooding can prove deadly. A report from the Centers for Disease Control and Prevention says many of those who perished in New York and New Jersey during Superstorm Sandy in 2012 drowned when their houses flooded.