We are getting into winter even though it doesn’t feel like it outside! This week I decided to focus on El Nino. There have been many questions on what this is going to mean for us and of course our concerns on the amount of snowfall. I wanted to explain what El Nino is and how this year’s El Nino may affect us.
The term El Nino was created just over 100 years ago to describe unusually warm waters that form right along the coast of Ecuador and Peru. This would usually happen near Christmas time and so they named it El Nino which is Spanish for “the boy child”. More recently El Nino refers to a larger reference area where unusually warm waters form. The area is the tropical eastern and central Pacific. (Longitudes:120W to 170W, Latitudes: 5N to 5S). This phenomenon of warmer waters is irregular but seems to occur generally every 3-7 years.
While the area of the El Nino is far away, the change in sea surface temperature over that area eventually affects us because it effects global changes in wind, pressure and rainfall patterns. Depending on how strong the El Nino is and how long it lasts will determine how other areas of the world are affected.
Last week the Climate Prediction Center released the latest on this year’s El Nino. It actually indicates that this year’s has strengthened into a moderate El Nino where the last several months it had been in the weak category. What this means for us is there are greater odds that we are going to see above average temperatures and below average snowfall. This does not mean we may not see a few spells of cold temps or that we will not see a few major snowstorms. In fact, we could have a major snowstorm producing large amounts of snow but if temperatures after the snowfall remain above freezing the snow will melt quicker. Another huge factor is how long the El Nino will last. The latest models want to keep it at least moderate strength through February.
When looking at previous El Nino years, it is important to note if it was a weak, moderate or strong El Nino. The last strong El Nino was in 1997-98. This one did produce temperatures above average; we also saw above average precip but below average snowfall (so more rain then snow). This means that not necessarily will we see less precip, but if temperatures are warmer it will come as liquid. In the last moderate El Nino which occurred in 2002-03 we saw above average temperatures and below average precip and snowfall. A local National Weather Service meteorologist mentioned to me that temps related with El Nino seem to follow the trend (above average) but there is not as much of a pattern when we are comparing precip or snow. However looking at La Crosse data, we have only seen 6 above average snowfall seasons out of the 17 El Nino years dating back to 1957-58. The last two El Niño’s were weak and they occurred in 2004-05 and 2006-07. Both of these years in La Crosse there was above average snowfall and precip.
In Wausau the strong El Nino of 1997-98 actually produced near 60” of snow which is just over our average of 58.6”. However, if you speak to anyone what people would remember is a season without a winter. Most of the snowfall amounting to “normal snowfall” came during a two week period in January. The rest of the season was warm with little snow, hence making it poor conditions for winter activities or enthusiasts. The last moderate El Nino in 2002-03 produced 38” of snow which is close to 20” below normal. This was the year we saw two halves to winter. The first part of winter was mild with little snow but the El Nino began to weaken by the end of January. That left a decent winter from the second half of January through February with cold temperatures and decent snowfall.
Justin has blogged about this topic several times and has lived in the area through the past 4 El Niño’s. I thought he would have some good insight and I have posted a video interview I conducted with him - check it out under “What Does El Nino Means For Us?”
The most important concept to grab is that everything is about percentages. Now that we are in a moderate El Nino there is a greater chance that we will see the above average temps and below average snow.