El Nino sea surface temperature anomaly final.jpg

The large red area shows the warmer than normal waters that create El Nino conditions on January 14, 2016.

(NOAA/Mark Torregrossa)

The current El Nino has just been ranked as strong as the 1997-98 El Nino. Since that El Nino was the strongest on record since 1950, our current one is now tied with 1997-98 as the strongest.

Consistent ranking of El Nino began back in 1950. It is ranked by taking the sea surface temperature anomaly in a large area of the Tropical Pacific. This anomaly is given a monthly value, and then three months are averaged. This index is called the Oceanic Nino Index, or ONI.

The ONI in December was ranked as 2.3degC warmer than normal, which is the same ranking as the peak of the 1997-98 El Nino. The current ONI of 2.3degC is for October, November and December 2015. So there is the chance when January 2016 temperatures are added in, the current El Nino could be ranked as the strongest.

El Nino is not just about warm ocean temperatures. It is also characterized by how the atmosphere reacts and changes to the warm ocean. The Climate Prediction Center says low-level winds in the El Nino region were abnormally strong from the west during December. This gives us one reason why December was so warm across the U.S. Warm, tropical winds from the southwest overpowered typical cold, northerly December winds.

The Climate Prediction Center believes El Nino has peaked in strength. Ocean temperatures in January have started to cool. But given the strength of the current El Nino, ground truth weather effects from El Nino are expected to continue through the rest of winter.

This means El Nino's warming effect on Michigan winters is expected to continue. In other words, this recent cold snap probably does not signal an end to an overall warmer than normal winter temperature pattern here in Michigan.

In fact, Matthew Rosencrans from the Climate Prediction Center says, "Wind anomalies at about 4-5,000 feet over ocean are just as strong as 1997, but later than 1997, so could have lagging impact into spring." He says this El Nino peaked or will peak later than the 1997 El Nino.

Finally, El Nino is expected to cool down and turn the tropical ocean into what is called a "neutral state" by early summer. The big question after that will be if the waters continue to cool, and become a La Nina. La Nina is when the ocean temperatures in the same region become cooler than normal.

Related: If you like El Nino, you may love La Nina

There is some indication that La Nina tends to bring Michigan a warmer than normal and drier than normal summer, especially late in the summer.

If you have any questions or comments, please post below.

MLive Chief Meteorologist Mark Torregrossa has been forecasting Michigan weather for more than 25 years. He's been chief meteorologist at three television news stations in Michigan, and he's an avid gardener and hunter. Email him at mtorregr@mlive.com and find him on Facebook at facebook.com/mark.torregrossa and Twitter @weathermanmark