DES MOINES, Iowa — A cooler than normal and wetter than average winter is expected for central Iowa.

The waters over the eastern Pacific have a big influence on the long-term forecast for the United States and around the world. These pattern shifts are referred to as El Nino and La Nina. El Nino occurs when the trade winds weaken, causing warmer water over the eastern Pacific. La Nina is the opposite, which happens when the trade winds strengthen and cause cool waters over the eastern Pacific.

We’re currently in a La Nina phase, but it appears to be weakening. State Climatologist Justin Glisan notes that weak La Nina phases usually lead to above average snowfall in Iowa, while strong La Nina phases are associated with below normal snowfall. Moderate periods of La Nina don’t have a particular correlation for central Iowa.

As our La Nina phase weakens, we will enter what is known as an “ENSO Neutral” phase, which essentially means that water temperatures in the eastern Pacific are around average. Glisan notes that those years have brought cooler and wetter springs to central Iowa in the past.

So, considering the weakening La Nina trend and a potential transition to an “ENSO Neutral” phase, we are expecting temperatures to be cooler than average and wetter than average precipitation (particularly in central and eastern Iowa).

The WHO 13 Weather team expects this season to bring us above normal snowfall, around 38″. That’s compared to our normal amount from December to April, which is about 32″.

Of course, there are exceptions to what has happened in the past given a certain atmospheric pattern, and climate models can be wrong. Stay with WHO 13, the local weather leader, to get you through the upcoming winter season!