Between the November 17 tornado outbreak and the Thanksgiving holiday, I did not post this earlier – NOAA released their winter forecast on November 21. For Illinois, there are equal chances (EC) of above, below, and near-normal temperature and precipitation. What does that mean? It means they found no strong evidence of unusually cold/warm/wet/dry conditions this winter in Illinois.
Part of the reason for this not-so-exciting winter forecast is that we have neither El Niño (warm water) nor La Niña (cold water) patterns occurring in the Pacific Ocean. Instead we have the “neutral phase” where sea surface temperatures in the Pacific Ocean along the equator are close to the long-term average. The Climate Prediction Center expects us to be in the neutral phase of the pattern through at least spring of 2014.
There has been some research on what happens in winter during the so-called “neutral phase”. The map below is based on a scientific paper by Wayne Higgins and others in 2002. They found that there is a tendency for the jet stream to stay south of Illinois, leaving us in colder-than-average conditions. It is interesting that this pattern fits the temperature forecast for the central US over the next 14 days.
If only forecasting winter weather was as easy as tracking the conditions in the Pacific. Other forces may come into play including the Arctic Oscillation and the related North Atlantic Oscillation. And don’t forget the natural variability of winter that we love so much – warm one day, freezing the next, little snow for a month followed by one big storm. If you have lived in the Midwest for any length of time, then you know the drill. Stay warm and safe.
Higgins, R. W., A. Leetmaa, V. E. Kousky, 2002: Relationships between Climate Variability and Winter Temperature Extremes in the United States.J. Climate, 15, 1555–1572.