A third straight winter of La Niña conditions are expected, according to The Climate Prediction Center (CPC).
The phase of the El Niño-Southern Oscillation (ENSO) is one of the most important climate phenomena when it comes to forecasting as well as the weather’s outcome in a given location. This is because this has the ability to change the global circulation, which then has an impact on temperatures and precipitation.
A La Niña is when the sea surface temperature along the equator in the eastern Pacific Ocean is at least 0.5°C cooler than the long-term average. That is something that we have seen during the last two winters: 2020-2021 & 2021-2022. As you can see in the graph above, we have remained in a La Niña pattern much of the last two years except a few months in the mid of 2021.
Right now, the probability of a La Niña looks to be at least 60%, if not higher, through February. If this happens, this would only be the third time in the last 73 years, where we had three straight winters of La Niña conditions. The only other times this has happened is in the mid-1970s, and late 1990s early 2000s.
What Does It Mean For The Tri-State?
When ENSO is in a La Niña phase, it usually leads to the Polar Jet Stream shifting further to the south, which in turns also brings in colder temperatures into the northern United States. Here in the Tri-State, that southward shift in the Polar Jet Stream generally leads to a wetter winter pattern.
While it would be easy to say that is how our winter will wind up, that to me seems like a cop out. Let's see if we can use past data to see if there are any trends to pick up on.
Something to ponder is what a normal winter brings to those of us in the Tri-State. While the winter months are defined as December, January, & February, we can see snow from October through April. So when it comes to snowfall, the seasonal average for Cincinnati is 23.3 inches over the last 30 years. We will use the winter months to define the average temperature, which equates to 33.9°. These numbers will be our comparison points.
In the last 30 years, we have seen nine El Niño winters, nine Neutral winters, and 12 La Niña winters. Below is the list of the 12 years with La Niña phases and where we finished among snowfall and temperatures.
Of those 12 winters, six finished above average in snowfall, while six finished below. As far as temperatures, seven finished below normal while five finished below normal. That doesn’t really lend itself to a trend one way or another. However, what makes this winter a little different is that it will be part of a consecutive La Niña seasons.
Among the winters listed above, there were five such occasions that had back-to-back (even one instance of back to back to back) La Niña. All five of those winters ended with below average snowfall, and three of the five finished with an above normal temperature.
It is still too early to know if we will definitively see a La Niña this winter, but if we do, I would suspect that we see a warmer than normal winter with below normal snowfall.
If we switch into a Neutral Phase that would change things quite a bit, and likely lead to a colder than normal winter. We shall see!
