How accurate are seasonal predictions?

LANSING, Mich. (WLNS) – Last week the Climate Prediction Center released its winter outlook for the United States. But how accurate have these seasonal predictions been in the past?

For this upcoming winter season, the Climate Prediction Center has forecasted a warmer and drier air mass for the South, and a cooler, wetter air mass for the Northwest.

But for us in mid-Michigan, we have an equal chance of seeing above or below-average temperatures, and a pretty good chance that we see above-average precipitation.

But it turns out that when it comes to the accuracy of these predictions, since they started in 1955, the forecast has yet to hit a perfect score.

After each season, the Climate Prediction Center verifies the accuracy of its forecast using the Heidke Skill Score, which compares how often the forecast category correctly matches what is observed across the country as a whole.

On this scale, 100 is a perfect score. Anything above zero says that the forecast was more accurate than looking just at seasonal averages, and anything below zero shows that the forecast has more inaccuracies than precisions.

Since 1955, the temperature outlook will generally score between zero and 40 on the Heidke Skill score, with three forecasts scoring above 80.

But in just the past five years only four forecasts scored above 60, and there were 15 times that it scored at, or below zero.

Even with that in mind, it turns out that temperature forecasts from the Climate Prediction Center are more accurate than those for precipitation.

Generally, precipitation scores between zero and 10, and in the past five years only five forecasts scored above 30, and five scored below zero.

We can also break down the accuracy of the forecast for a certain area.

Based on past forecast data, the temperature forecast is more accurate for the Southeast than the Midwest and Southwest. With precipitation outlooks, they tend to be more accurate for the same area, towards the Gulf Coast.

In contrast, areas in the Midwest and Northeast usually see the opposite of what forecasters predict for the season.

Overall, these forecasts still give us a general idea of what we can expect for a certain season, but they should only be used as general guidance to help communities prepare for what is likely to come in the months ahead and minimize the weather’s impact on lives.