Fall may have only just begun, but it’s not too early to look ahead at the coming winter and what kind of weather Kentucky might be in for this year.
This year, scientists at the nation’s Climate Prediction Center have confirmed the emergence of a new El Niño, and it’s expected to gradually strengthen as winter approaches. For the U.S., that generally means a winter pattern of cooler, wetter conditions in the South and warmer, drier weather in the North. But what about Kentucky, which sits in the middle of these two zones?
Here’s what to expect from this coming winter in Kentucky, with insights from meteorologist Tom Reaugh with the National Weather Service in Louisville.
What is El Niño?
As explained by the National Oceanic and Atmospheric Administration, the El Niño Southern Oscillation, often abbreviated as ENSO, is a single climate phenomenon with three stages. There’s El Niño itself, La Niña (El Niño’s cooler opposite) and a neutral phase in the middle of the continuum. El Niño and La Niña episodes typically last nine to 12 months, though they can sometimes last for years, according to NOAA.
El Niño is a warming of the ocean’s surface in the central and eastern tropical portions of the Pacific Ocean. By far the world’s largest ocean, the Pacific Ocean has the power to influence weather in ways that ripple out across the globe, and the warmer water acts as rocket fuel for more powerful hurricanes and typhoons.
During El Niño, the trade winds that blow from east to west weaken or even sometimes reverse themselves, blowing from west to east. The effects can be felt worldwide. Indonesia, one of the rainiest parts of the planet, experiences a heightened risk of drought or fires while rainfall over the tropical Pacific Ocean intensifies.
El Niño also influences the path of the jet stream — a fast, narrow current of air flowing from west to east that encircles the globe. Under El Niño, the jet stream dips south and spreads further east across the U.S.
During the winter, this leads to wetter conditions than usual across the country’s Sun Belt — from southern California to North and South Carolina — and to warmer, drier conditions in the North.
Does El Niño mean Kentucky will have a bad winter?
While El Niño brings cooler, wetter conditions to the Sun Belt, it also brings warmer, drier conditions to the northern half of the country.
Kentucky sits in the middle of these two zones, but it does tend toward drier conditions during an El Niño winter. There is no statistically significant increase in the chances of cold or warm temperature extremes in the Bluegrass State under an El Niño winter, according to the weather service.
However, it’s worth remembering, NWS meteorologist Reaugh said, this is just typical El Niño behavior. Separate El Niño events can and do vary and how different effects on seasonal weather.
“The El Niño for this coming winter is expected to be moderate or strong,” Reaugh said.
The meteorologist summed up the typical pattern during a strong El Niño.
“For precipitation, the Ohio and Tennessee Valleys, from Tennessee through Kentucky to Indiana and Ohio, average slightly drier than normal conditions (roughly about 10% drier),” Reaugh wrote in email responses to questions from the Herald-Leader. “For average maximum temperature, there is very little change from normal.”
Does an El Niño mean Kentucky will get little to no snow this winter?
According to Reaugh, an El Niño doesn’t necessarily mean a less snowy winter here in Kentucky.
“We may receive below normal precipitation, but if the majority of the precipitation that does fall occurs when temperatures are below freezing, we can still end up with a snowy winter,” Reaugh explained. “Having said that, looking at just the 10 strongest El Niños, Central Kentucky does tend to be slightly less snowy than normal. However, when taking all El Niños into account, there’s almost no signal.”
It’s worth remembering, Reaugh said, El Niño isn’t the only factor that affects Kentucky weather during the winter.
“El Niño is just one player among many. We pay El Niño (and La Niña) a lot of attention because it’s one of the more forecastable large scale phenomena, and has been well studied over many years,” Reaugh explained.
Do you have a question about weather in Kentucky for our service journalism team? We’d like to hear from you. Fill out our Know Your Kentucky form or email email@example.com.