Heading into winter, the temperature of Lake Michigan's waters are well above average, which influences the weather in Chicago
A recent report from the Chicago Tribune highlighted the effects of climate change on Lake Michigan. This fall, the Chicago area experienced higher than average minimum temperatures.
“What was kind of jarring was the consistency of the warmer-than-normal conditions,” state climatologist Trent Ford told the Tribune. “And the lack of cool nights.”
As a result, Lake Michigan has not experienced its typical cooldown. Currently, the surface temperatures of Lake Michigan waters are much higher than average.
According to the Tribune, "Increasing minimum temperatures are a sign of the warmer and wetter conditions expected for Illinois, as human actions — the burning of fossil fuels and resulting emissions — continue to fuel rapid climate shifts."
What does a warmer Lake Michigan mean for Chicago's winter?
Warmer waters can result in lake effect snow. The government's weather predictions for the next few months for the Chicago region are more snow than usual and above-average temperatures.
Lake effect snow occurs when cold Canadian air passes over warm Lake Michigan waters. According to the National Oceanic and Atmospheric Administration (NOAA), "The air rises, clouds form and grow into narrow band that produces 2 to 3 inches of snow per hour or more."
Lake effect snow around the shoreline of Chicago can extend for 50 miles and under the right conditions, even further. Meteorologist Tom Skilling says, "with strong winds, snow showers can travel as far west as Rockford and Peoria, and on rare occasions the Mississippi River."
Ice coverage on the lakes lessens lake effect snow. But with higher temps, the ice coverage will likely be delayed this year.
What else influences the weather?
While the temperatures of Lake Michigan have a strong influence on lake effect snowfall in the Chicago area, there are other factors at work as well.
This winter, the U.S. is under the influence of La Nina, which brings more precipitation to the northern states. According to NOAA, there is a 90% chance that La Nina conditions will persist through the winter, and a 50% chance they will still be here into spring.
How precise are long-term weather forecasts?
Predicting the weather is an inexact science. It's especially difficult to predict exact weather patterns very far into the future. But there are some things meteorologists look for that can help predict the weather.
Long-term prediction is less precise than short-term. There are just too many factors and complications to get very precise. Weather predictions that are made beyond two weeks are usually unreliable.
However, meteorologists can make seasonal predictions which they call "probabilistic forecasts".
While nobody can tell you today if it will snow on New Year's Eve, meteorologists can tell us generally that the Chicago area will likely have higher than average snowfall for the upcoming season.
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