Federal agencies: Poor communication hurt accuracy of forecasts ahead of Nashville deluge

Poor communication hurt Tenn. flood forecasting

NASHVILLE, Tenn. — A National Weather Service hydrologist says the extent of flooding in Nashville could have been more accurately predicted if the U.S. Army Corps of Engineers had kept them up to date on how much water it was releasing into the Cumberland River.

“That’s the information we used to put out the forecast for Nashville,” Jim Noel said. “If we had information that was several hours old, that’s the information that we worked off of.”

At a joint news conference on Thursday, officials from both agencies described communication problems during the recent flooding that killed 22 people in Tennessee and caused more than $2 billion in damage in Nashville alone.

Those problems included an almost 12-hour Internet outage at corps headquarters on Sunday, May 2. The weather service, not the corps, is responsible for predicting flood levels and issuing warnings to the public.

The corps official in charge of water management for the Nashville district, Bob Sneed, downplayed the significance of the outage, but also said employees had to use their cell phones to retrieve data from river gauges until the network was restored.

Also that day, as parts of the city were flooding, the corps was constantly adjusting the amount of water allowed to flow through Old Hickory Dam northeast of the city. Water released from the dam takes about six to eight hours to reach downtown Nashville.

Flows were adjusted 22 times that day, Sneed said, but the corps only communicated with the weather service five times. The last time was at 11 p.m., after NWS officials looking at data from river gauges became concerned that the river was rising much faster than they had predicted, Noel said.

At that point they called the corps directly and learned it was discharging much more water than they had previously been told: 220 cubic feet per second, not the 150 they had based their predictions on after a 7 p.m. conversation.

Larry Vannozzi, the meteorologist in charge at the NWS Nashville office, defended his office’s warnings, saying they were constantly updated throughout the three days the water was rising.

Many people have complained that they were not warned to evacuate their homes until it was so late they had to wade through flood waters to rescue boats. Sen. Lamar Alexander, Rep. Jim Cooper and others have called for an investigation into the corps’ actions and whether better communication could have prevented some of the damage.

On Thursday, Sneed defended the release of water from its Cumberland River dams, saying that the reservoirs were at or past capacity and that flooding would have been worse without the controlled release of water at certain times.

Vannozzi said the weather service will be conducting an assessment of its warnings and looking at what it could have done better.

The Corps will be conducting a similar assessment, Sneed said.

Both agencies said the unprecedented amount of rain — 13.5 inches in 36 hours at the Nashville airport — made this flood especially challenging. Sneed said it was like a flash flood of the Cumberland River, something that sounds almost impossible for such a large body of water.

“The record rainfall pushed the corps and other agencies beyond our capabilities,” he said.