Failure to accurately predict flood levels in Nashville last May and issue effective warnings is leading to policy changes within the National Weather Service. The agency released its post-flood assessment Wednesday.

The National Weather Service issued flood warnings leading up to and during the historic rainfall. But Jane Hollingsworth, who led the agency’s post-flood assessment team, says people weren’t sure if the warnings applied to them.

“They are sometimes difficult for people to decipher. We have a team of social scientists working with us to make sure the warnings we do send out are clear and concise and that they invoke the actions that we want people to take.”

Hollingsworth says flood warnings are particularly difficult because some people may need to stay off the roads while others need to find higher ground.

Because of the Nashville flood review, the weather service is also developing street-level maps for the city that show flood predictions. Such maps have already been made for 60 other cities.

Unreliable predictions for flooding of the Cumberland River have led to the most finger pointing. Weather Service officials defend their forecasts, considering the unprecedented rain event, but they say meteorologists should have a closer relationship with the agency controlling the dams, in this case the Army Corps of Engineers.

Floods Put Nashville on Fast Track for Inundation Maps

Sixty cities have predictive maps where forecasters can show who might be in the way of – or cutoff by – floodwaters. National Weather Service director Jack Hayes says he has expedited Nashville’s maps, which should be ready by spring.

“Our view is a picture is worth a thousand words. And this is going to create a picture where if you’re living in some particular neighborhood, you will be able to see that you’ve got threat and you can then think about what am I going to do if this threat increases.”

Hayes says the maps could be used by TV weathermen. He says the challenge is figuring out how the inundation maps could be effective over weather radios or by text message.

The post-flood assessment also suggests the National Weather Service office in Nashville needs more meteorologists working during weather emergencies.

Web Extra

Hear Hayes explain the need for automated information about flow through dams.