GRAND RAPIDS, Mich. (April 11, 2014) — There’s been a great deal of media coverage in the past week about forecasts for the weather phenomenon known as El Niño to develop later this year. While there are significant signs that El Niño is likely to occur, much of the discussion of what that may mean is merely speculation at this point.
First, let’s review what El Niño is. Generally speaking, El Niño refers primarily to the unusual periodic warming of ocean water in the Pacific off the coast of South America. Along with that come a number of other impacts, many of which occur far away from the source of the phenomenon. We often refer to these effects as “teleconnections.”
At this point, it’s safe to say that an El Niño event is more likely than not by later this year. Thursday, the government’s Climate Prediction Center came out with a revised discussion that increased the chance of El Niño occurring to “greater than 50%.” That’s lower than many other outlooks from international government agencies and research groups. The CPC was a bit conservative, in part, because forecasts made in the spring are historically less accurate than those made at other times of year.
Where more uncertainty lies, though, is in the potential for an unusually strong El Niño event from late 2014 into 2015. Some of the headlines have used terms like “Super” or “Monster” El Niño to warn of the devastating impact that the phenomenon can often have on global weather patterns. Past El Niño events have been blamed for droughts, extreme heat, wildfires, and extreme rain and flooding in different parts of the world. In the United States, the strongest connection to El Niño is typically recognized on the West Coast and in the South. The West Coast, in particular, can often see much higher-than-average rainfall.
It is important to note, however, that we are still looking at long-range projections of a large-scale event that can have varying impacts on small-scale weather situations. Much less certain than the development of El Niño is the forecast of how strong an El Niño event may occur. As such, you should take information that projects catastrophic conditions or, for that matter, ANY type of weather as a foregone conclusion with a grain of salt. Keep in mind a couple of important points that also relate to El Niño’s potential effects on West Michigan:
- Not all El Niño events are the same.
- Even within El Niño seasons, the typical spectrum of weather still exists — El Niño only shifts the balance toward certain types of weather patterns.
So what does El Niño mean for West Michigan in general? For one thing, the primary effects of the phenomenon are felt in the winter, not the spring or summer. And we’re still likely a few months away from El Niño development; so, don’t expect any changes we can attribute to El Niño until at least this fall and winter.
There are a handful of El Niño seasons that we can compare to start making some basic conclusions about its possible effects. These include 1957-58, 1965-66, 1968-69, 1972-73, 1982-83, 1986-87, 1987-88, 1991-92, 1994-95, 1997-98, 2002-03, 2004-05, and 2009-10. These events were of varying intensity, with the strongest coming in 1965-66, 1972-73, 1982-83, and 1997-98.
The two main signals that El Niño gives us in West Michigan are shifts toward warmer temperatures and less snowfall. Several of the least snowy winters on record came during strong El Niños, particularly 1982-83 (35.9″) and 1997-98 (59.8″). These are two of the strongest El Niño events on record, and some forecasters are already comparing the next year to these seasons.
But, as mentioned above, not all El Niños are the same. In fact, the stretch from 1976-78 was also a weak El Niño period, yet was known for some of the most brutal winter weather many West Michigan residents can remember. In general, the stronger the El Niño, the more likely we are to see warmer temperatures and reduced snowfall. A weak El Niño has much less correlation with any specific type of weather locally.
So, in conclusion, it’s important to keep in mind that we’re talking only in terms of probabilities at this point. That’s how long-range forecasting works — we talk about increased chances of certain conditions, which is very different than saying that those conditions are going to happen. But if you dread the idea of a repeat of this past winter, you can rest a little easier knowing that El Niño tilts the scales in the opposite direction.
For more scientific discussions of El Niño forecasts: