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A rare 3rd La Niña expected this winter: Here's what it means for our weather

Typical La Niña Precipitation Pattern
Posted at 4:26 PM, Aug 18, 2022
and last updated 2022-08-19 09:15:41-04

A third straight winter of La Niña conditions is expected, according to The Climate Prediction Center (CPC).

The phase of the El Niño-Southern Oscillation (ENSO) is one of the most critical climate phenomena regarding forecasting and the weather’s outcome in a given location.

This is because this can change the global circulation, which then impacts temperatures and precipitation.

Monthly Sea Surface Temperatures ENSO
Three-year history of sea surface temperatures in the Niño-3.4 region of the tropical Pacific for the 8 existing double-dip La Niña events (gray lines) and the current event (purple line). Of all the previous 7 events, 2 went on to La Niña in their third year (below the blue dashed line), 2 went on to be at or near El Niño levels (above the red dashed line) and three were neutral. Graph is based on monthly Niño-3.4 index data from CPC using ERSSTv5. Created by Michelle L’Heureux.

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. We have seen that during the last two winters.

As you can see in the graph above, we have remained in a La Niña pattern for much of the last two years exceptfor a few months in the mid of 2021.

ENSO FORECAST.jpg
NOAA Climate Prediction Center forecast for each of the three possible ENSO categories for the next 8 overlapping 3-month seasons. Blue bars show the chances of La Niña, gray bars the chances for neutral, and red bars the chances for El Niño.

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 were in the mid-1970's, late 1990s, and 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, bringing colder temperatures to the northern United States. Here in the Tri-State, that southward shift in the Polar Jet Stream generally leads to a wetter winter pattern.

La Niña Temperatures
Typical La Niña Temperature Pattern
Typical La Niña Precipitation Pattern
Typical La Niña Precipitation Pattern

While it would be easy to say that is how our winter will wind up, that 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 has been 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.

A Breakdown of the Last 12 La Niña Winters
The last 12 La Niña Winters

The above table corresponds to data from Cincinnati, Ohio and is not representative of the conditions in Central Texas.

Of those 12 winters, six finished above average in snowfall, while six finished below. Regarding temperatures, seven finished below normal, while five finished below normal. That doesn’t lend itself to a trend one way or another. However, this winter is a little different because it will be part of a consecutive La Niña season.

Among the winters listed above, five such occasions 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 will 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!

La Niña conditions expected this winter

Brandon Spinner at WCPO first reported this story.