IEM Daily Feature
Friday, 30 October 2020

Developing La Nina

Posted: 30 Oct 2020 05:35 AM

The featured chart presents the combination of monthly average temperature departures for Des Moines along with the El Nino 3.4 index value. The La Nina (negative El Nino index) condition continues to strength with some further strengthening expected this winter season before a transition next year to possible El Nino. So what does this index over the equatorial Pacific Ocean have to do with Iowa's weather? Well sometimes a lot and other times not so much! The index covers a very important region of the planet that drives large scale transport of heat, moisture, and energy. The strength of the influence of this index on our weather depends on the time of year and many other things. The chart shows a clear influence from the "Godzilla El Nino" back in 2015 leading to many months of warmer than average temperatures, but other periods the influence is more nuanced. La Nina's impact for Iowa during winter months is not too strong, but favors wetter and cooler conditions than average. With October coming in cooler than average, we shall see what the rest of the cool season months have in store.

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Tags:   elnino