The National Weather Service has released its new 30-year climate normals, and the biggest takeaway from the new numbers is that Oneida — and Tennessee in general — are much wetter than they used to be.
Other take-aways: Slightly warming temperatures and declining snowfall.
That it rains more in Oneida than it used to was a poorly-kept secret. The Independent Herald has previously reported on the increased rain totals. But the new climate normals published by the NWS make it official.
The NWS uses a rolling 30-year average to determine climate numbers for the nation as a whole, for each state, and for specific locales. The numbers are updated every 10 years. The old climate norms in Oneida were determined using data from 1981 to 2010. The new norms are determined using data from 1991 to 2020.
And between 1991 and 2020, Oneida received an average of 58.12 inches of rain each year. That’s up significantly from just 10 years ago, when the average rainfall in Oneida was 53.9 inches.
As for snowfall, the plummeting averages continue. According to the NWS’s data, Oneida now averages just 5.5 inches of snow each winter, down from 9.4 inches under the old data that was updated in 2010.
Temperatures warmed across much of Tennessee but were relatively steady in Oneida. The average high temperature in July — the hottest month of the year locally — is now 85.4 degrees, unchanged from the 1981-2010 average. The average low temperature in January — the coldest month of the year — is 24.5 degrees, up slightly from 23.9 degrees under the old data.
Increasingly wet weather across Scott County and the northern Cumberland Plateau has led to more flooding and flood damages — such as washed-out culverts and minor mud slides — in recent years. In Oneida, the four wettest years on record have all occurred in the past four years. The wettest year, 2015, featured 72.6 inches of rain. That was followed by 70.8 inches of rain in 2019, 69.1 inches of rain in 2018, and 67.8 inches of rain in 2014.
Prior to 2014, the wettest year on record in Oneida was 1975, with 67.5 inches of rain.
Even drought years feature more rain than they used to. The most recent sustained drought in the Cumberlands was 2016 — the year of the horrific Gatlinburg wildfires and numerous other wildfires that scorched tens of thousands of acres across East Tennessee, including the Chimney Rocks wildfire in the Big South Fork National River & Recreation Area. That year barely cracked the Top 5 driest years in Oneida, with 46 inches of rain. By contrast, the calendar years of 1968 and 1953 featured significantly less rain, and 1963 and 1955 were also drier.
While the 30-year climate norm for Oneida is much wetter than it used to be, the numbers are still going up. If climate norms were based on 15-year averages rather than 30-year averages, Oneida’s average rainfall would be 60.4 inches per year.
Meanwhile, it’s also been no secret that annual snowfall is declining, although the National Weather Service’s numbers are considered suspect outside Tennessee’s major cities.
For example, while the NWS lists Oneida’s average snowfall at 5.5 inches, Jamestown has a new average of 18.9 inches of snow — up significantly from 13.9 inches.
Jamestown does receive more snow, on average, than Oneida. Its position on the western edge of the Cumberland Plateau allows that area to maximize the effects of orographic lifting — the phenomenon in which air rises as it hits terrain change, helping the air to cool and the moisture to condense into snow. However, it seems unlikely that the difference between the two towns are that significantly.
Additionally, Crossville’s new snowfall average is 14.1 inches, while even Cookeville — at 6.1 inches — is listed as receiving more snow than Oneida.
Nevertheless, declining snowfall averages were to be expected, as the new dataset of 1991-2020 removes the 1980s, which were a relatively snowy decade. The Cumberlands and much of Tennessee have been stuck in a relative snow drought since the mid 1990s.
As for temperatures, the average in Oneida for the year is now 55.1 degrees, up slightly from 54.7 degrees under the old data range of 1981-2010.
That temperature increase is similar to the increases experienced in Knoxville and Memphis. Nashville and Chattanooga saw their average temperatures increase more significantly, by at least a full degree. One possible explanation for the greater temperature increases in those cities is the so-called urban heat island effect. Concrete and asphalt absorb heat from the sun’s rays more efficiently than dirt, and take longer to cool after the sun has set. Thus, large cities are typically warmer than surrounding outlying areas, and the expansion of urban areas in Nashville and Chattanooga could account for greater temperature increases over the past 30 years.
One thing that remains true in Oneida is that the temperature doesn’t often get above 91 degrees. Even rarer is 100-degree temperatures. In fact, the temperature in Oneida has reached 100 or greater only three times in the past 30 years: 100 on July 7, 2012, 103 on July 1, 2012, and 103 on July 2, 2012. Those 100-degree days were the first in Oneida since the massive heat wave of 1980, which featured four days with official temperature readings of 100 degrees or greater.