What has happened to our Winter, people have recently asked. The answer is, El Niño. The weather and oceanic conditions in another part of the world can influence our weather here in the central Illinois region as well as the rest of the United States. With the onset of an El Niño episode, our winter temperatures will be warmer than normal. This is due to the current conditions in the central Pacific influencing the placement of the jet stream over the United States.

What is El Niño?

When an El Niño episode occurs, the prevailing tradewinds over the central Pacific Ocean weaken allowing a low-pressure cell that normally sits between South America and Australia shifts toward the western coast of South America. When this shift occurs, warm water will position itself off the South American coast causing above normal precipitation to fall over the South America. During an El Niño episode, fish populations off the South American coast will be reduced significantly due to the warm waters stiffling reproduction. In addition, mudd slides and major flooding occur increasing land degradation. On the opposite side of the Pacific, a high-pressure cell dominates the Australian and Indonisian region increasing drought conditions for which wildfires rage.

In other parts of the world, the episode causes a shift in the jet stream. In one part of the world, below normal temperatures would occur and in other parts, above normal temperatures prevail. As for the United States, warmer than normal temperatures occur in the northern third while normal temperatures occur in the southwestern portion. Precipitation will be above normal along the southern third as below normal precipitation occurs in the Midwest and Montana region.

Outlook

For the rest of the 2006-07 winter we can expect continued above normal temperatures. However, this does not mean that occasional cold snaps will not occur. Snow can be expected as well when temperatures drop below freezing but amounts will not be significant. The overall temperatures for the season will be above normal. Precipitation thus far has proved relatively significant, which will help in the coming months when crop planting begins.

Temperature Outlook for the United States, NOAA.

Precipitation Outlook for United States, NOAA.

References and Further Information

National Oceanic and Atmospheric Administration (NOAA)