Rainfall across the Tennessee Valley was 20% above normal last year, with more than 60 inches of rain falling across the region for the fourth consecutive year.
Mother Nature dumped nearly 63 inches of rain in Chattanooga during 2021, or nearly 8 inches more than in a normal year. The National Weather Service is forecasting another wetter-than-normal start to the new year in Chattanooga, even with the frigid temperatures expected in the next few days.
"We've seen higher rainfall totals in each of the past four years, which reflects the impact of [the climate pattern] El Niño warming the surface waters in the Pacific and bringing more rain in our region," Allan Diegan, a meteorologist at the National Weather Service in Morristown, said in a telephone interview. "Our forecasts for the next three months show a continued pattern of above-average rainfall."
But the soggy weather during much of last year was still less than in 2020, when nearly 73 inches of rain fell in Chattanooga. Across the Tennessee Valley, total rainfall averaged nearly 61 inches last year, or nearly 10 inches more than normal.
Rainfall in 2021 in the region still was well below the record high set in 2020, when the Tennessee Valley received 70.3 inches of rain, according to TVA. Chattanooga's soggiest year was 1994, when a record 73.7 inches of rain was recorded by the National Weather Service at the Chattanooga Metropolitan Airport.
The Tennessee Valley Authority, which manages the Tennessee River and its tributaries for flood control, power generation and recreation, is spilling water through all of its dams on the Tennessee River to help bring down rain-swollen reservoirs to their winter pool levels. James Everett, manager of river forecasting for TVA, said rainfall in the region has been above normal for the past four years in one of the wettest weather cycles in the 135 years that such records have been kept in the region.
"We expect to be spilling water through our dams most of the next week," he said.
TVA estimates its dams and flood control efforts averted about $170 million of flood damages last April during one of the region's biggest spring storms. In 2019 the system prevented approximately $1.6 billion in flood damages across the Tennessee Valley, with about $1.4 billion of that being prevented at Chattanooga.
During one rainstorm in Middle Tennessee last August, Waverly, Tennessee, received more than 17 inches of rain in a 10-hour period in a record-setting rainfall that sent floodwaters surging through Middle Tennessee and killed at least 22 people. But that rain event was localized and didn't impact most of the Tennessee Valley.
"The last time the Valley saw four straight years of over 60 inches of rainfall was 1972-1975," TVA spokesman Travis Brickey said in a telephone interview. "However, the 2018-2021 period saw about 13 more inches of rainfall."
The extra rainfall helped TVA's hydroelectric dams generate about 15,668 gigawatt-hours of electricity, or 15% more than normal. Brickey said that's enough energy to power New York City for nearly four years.
Although 2022 is beginning with what may be the coldest temperatures since 2018 on Friday morning, Chattanooga's overall weather last year was still slightly warmer than usual. The average temperature in Chattanooga during 2021 was 62.9 degrees Fahrenheit, or about 1 degree warmer than normal, Diegen said.
Contact Dave Flessner at dflessner@timesfreepress.com or at 423-757-6340.