GRAND RAPIDS, Mich. (WOOD) — You don’t have to be a weather expert to have heard the terms “El Nino” and “La Nina” and to know that they often have an affect on our weather here in the United States, especially in the winter time.
El Nino and La Nina are two sides of the same coin, so to speak. They are different phases of an atmospheric teleconnection pattern called ENSO, or El Nino Southern Oscillation. For those of you who are a bit unfamiliar with what this means, here is a simplified and quick break down.
Forecasters have discovered that the water temperatures in the Pacific Ocean, along the equator and off the western shore of South America, can have a huge impact with the weather patterns we see in the United States each winter. (Isn’t science amazing?!)
When it is running warmer than average, forecasters call this the El Nino phase.
When the water is running colder than usual in this spot, forecasters call this the La Nina phase.
Changes in the ocean temperature in this key location can often tip off forecasters in the U.S. as to what our weather will most likely be for the coming winter. Often, the ENSO cycle doesn’t have as big of an affect on summer weather.
It’s also important to remember that the ENSO phase isn’t the only thing that comes into play for our winter forecasts. In fact, it is a delicate balance of many, many, many factors. However, if we are seeing a particularly strong La Nina signal or a particularly strong El Nino signal, it often is strong enough to drown out the other factors that play into the forecast. Weak El Nino or La Nina years can be much more difficult to forecast for.
Still, this is what our storm track usually does on a strong El Nino year.
This usually gives us a warmer and drier winter.
Here is what usually unfolds for us during a strong La Nina year.
La Nina years usually give us a colder and wetter winter.
ENSO neutral years are years where the water in the western equatorial Pacific aren’t running warmer or colder than usual by a significant amount. This is what the storm track usually looks like during neutral years.
This year, we have had an ENSO neutral phase for winter. This has not been the case for us this season though. We have seen warmer and wetter conditions this season. In fact, our snow deficit in West Michigan has been purely do to a lack of lake effect snow.
In short. We can’t push the blame on our winter on the ENSO phase or a change in phase. The biggest reason we’ve been warm and wet is because the North Atlantic Oscillation (NAO) has refused to allow too many visits from the Arctic cold. The NAO is another big player in our storm track, along with ENSO, each year. Since our ENSO cycle has been neutral, the NAO has had much more control over our storm track this season.
So even though the polar vortex and chilling cold have formed in the Arctic this season, the frequent positive NAO cycle has kept the cold largely away.
As for an early spring? Well, it’s possible! But just like this winter, it will depend a lot on the NAO phase. The NAO can flip quickly and drastically. We are expecting a warmer than average March at this point, but we should keep on our toes for March just in case.