Why did East Tennessee flood warnings seem too late during Hurricane Helene?

When Kriston Hicks first got an alert of a flash flood emergency at 9:20 a.m. Sept. 27, the home she shared with her 78-year-old grandfather in Hampton, Tennessee, was already doomed.

“I was wading through water to get my disabled grandfather into the van to leave because I had decided on my own that we needed to evacuate,” Hicks told Knox News in a text Oct. 3, the day after her home was demolished. “No one came to tell me. There is no siren in Hampton.”

The Doe River watershed in Carter County was one of several in East Tennessee that swelled to historic levels as remnants of Hurricane Helene drenched the southern Appalachian mountains in what the National Weather Service said was a once-in-a-millennium rainfall event.

In the National Weather Service office in Morristown, which covers East Tennessee, meteorologists were coordinating with local emergency management officials in several counties to issue warnings.

So, why did the warnings seem to come too late for many people across the region?

The answer lies partly in how the National Weather Service issues flash flood warnings, with emergencies and wireless text alerts reserved for “imminent or ongoing” severe flooding, said Morristown meteorologist Brandon Wasilewski.

Three levels to flash flood warnings in East Tennessee

People reading NWS updates on social media in the days leading up to the generational flood, which claimed at least 12 lives in Tennessee, got a sense of the danger ahead.

By Sept. 25, the NWS office in Morristown was already warning of “extreme risk of life-threatening flooding” along the Tennessee-North Carolina border as Helene moved through. At that point, the office had issued only a flood watch.

Residents in border counties did not get a wireless alert of emergency flash flooding until mid-morning on Sept. 27, when the flooding was already underway.

The National Weather Service needs to have confirmation of life-threatening flooding and “catastrophic damages occurring or imminent” before sending out a rare flash flood emergency, Wasilewski told Knox News.

Text alerts go out once the office adds a “considerable” or “catastrophic” tag to the flood warning, triggered by reports that “flash flooding capable of unusual severity of impact is imminent or ongoing,” Wasilewski said.

One trigger for the highest “catastrophic” tag is that multiple water rescues have occurred. The service relies on local emergency managers to handle evacuation orders.

“We always want to try to be proactive,” Wasilewski said. “We’re the ones that send it out, but we want to make sure that it’s risen to that level.”

While the National Weather Service issues flood warnings for specific rivers, it does not have a mechanism to alert specific communities at special risk of flooding. That’s something the service would like to add in the future, Wasilewski said.

“We don’t have the capability at this time specifically, and that’s why we do rely on more of the local officials,” Wasilewski said. “Whenever we do have an event of this magnitude, this is something that we always try to review and try to learn from.”

The week before the storm was already a strange one for weather in East Tennessee. On Sept. 24, East Tennessee recorded its first ever September tornado, an EF-1 twister in Hancock County with 110 mph winds.

The region also got 2-4 inches of rain before Helene even arrived as a tropical storm, which saturated the ground and caused fiercer runoff later on.

Some residents didn’t make much of flood warnings

Three rivers in particular carried a surge of floodwater from western North Carolina to East Tennessee – the French Broad, Nolichucky and Pigeon rivers. The hard-hit town of Erwin sits on the Nolichucky in Unicoi County.

Zully Manzanares, a Head Start program coordinator in Erwin, saw the flash flood warnings that began the night of Sept. 26 but didn’t realize the danger.

“We’ve gotten them before, but I don’t think the alerts were enough to make us realize like that it was going to be to the extent that it was,” Manzanares told Knox News. “The alerts were coming, but I don’t think that they were to the extreme that they needed to be so that people would have taken it more seriously.”

Daniel Dassow is a growth and development reporter focused on technology and energy. Phone 423-637-0878. Email daniel.dassow@knoxnews.com.

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