If El Niño returns, what does it mean for us?

MILWAUKEE (WITI) -- It’s probably the catchiest term in the meteorologist’s lexicon, El Niño. This global phenomena may not directly cause weather extremes in our corner of the world, but it certainly can tip the scales in favor of them.

So what is El Niño and when will we see it again? In some years, warmer than normal water pools in the eastern Pacific Ocean near South America while normal water temps remain near Indonesia and Australia. This is an El Niño event. A La Niña event is nearly opposite with warmer waters in the west (Indonesia) and cooler waters in the east (South America).

The greatest affects of El Niño are generally felt in winter. That’s when NOAA’s Climate Prediction Center believes it could return with full force. The most recent monthly forecast from the CPC states “chances of El Niño increase during the remainder of the year, exceeding 50% by summer.”

This prediction tells us it’s more than likely we’ll see El Niño conditions develop in the coming months and strengthen around the time the leaves hit the ground in southeast Wisconsin. The prediction is based off computer models taking in water temperatures near the equator in the Pacific Ocean.

These events can alter wind and weather patterns thousands of miles away. For us, El Niño brings a greater chance of warmer than normal temps with less snow over winter. The important word in that sentence is “CHANCE”. El Niño acts as one cog in our weather machine. Other factors can overcome the influence of El Niño, especially if the event is weak.

Winds that blow from east to west weaken, allowing warmer water to spread east to South America.

So let’s look at a few of the more recent, strong El Niño winters. In 1991-1992, 1997-1998, and 2009-2010 the surface temperatures in the eastern Pacific reached at least 1.5° Celsius (2.7° Fahrenheit) above normal. That rise sounds pretty minor but its influence is much more substantial.

The sample is small but the results cannot be ignored, especially when it comes to temperature. For the months of December, January, and February here’s what we El Niño helped bring to Milwaukee:

’09-’10 Temperature: +1.4° above normal

‘97-’98 Temperature: + 8.5° above normal

’91-’92 Temperature: +7.5° above normal

’09-’10 Snowfall: +1.7” above normal

‘97-’98 Snowfall: -0.3” below normal

’91-’92 Snowfall: -10.8” below normal

You can see how the results don’t always match a typical El Niño winter but the overall trend is clear. So if El Niño does develop as expected our upcoming winter may be the complete opposite of the brutal cold and snowy winter we just kicked off our property.

Nothing is certain, we’re simply talking probability so don’t sell your snow blower and Thinsulate gloves just yet. Though you shouldn’t need them as often this winter.