Latest Weather Outlook for Winter Months


Published on November 6 2017 4:20 pm
Last Updated on November 6 2017 4:24 pm


La Nina conditions in the Pacific Ocean favor a wet winter in the Great Lakes states and Upper Midwest.

But that doesn’t necessarily mean Illinoisans could be shoveling a back-breaking amount of snow in the months ahead, according to Jim Angel, state climatologist with the Illinois State Water Survey.

“Wetter-than-normal conditions are favored in Illinois this winter,” Angel said. “But that doesn’t always translate into more snow. A couple of big rain events could give us those wetter conditions.”

What fuels the possibility of the recent wet weather pattern, which produced the 10th wettest October on record, carrying over into winter?

A typical La Nina pattern features the jet stream positioned over the Great Lakes more frequently, thus leading to more storm activity, Angel noted.

There was about a 55 to 65 percent chance of La Nina developing through the fall and winter, based on the National Weather Service winter outlook last month.

Meanwhile, the NWS outlook for winter temperatures was neutral in the northern half of Illinois, meaning equal chances of above, below or near-normal temperatures. In southern Illinois, though, NWS projects warmer-than-normal temperatures this winter.

The outlook could change, though, based on the development of La Nina along with other factors.

“For example, the Arctic Oscillation and the dreaded Polar Vortex cannot be reliably predicted more than two weeks in advance,” Angel said.

And, even if La Nina materializes, that doesn’t guarantee a wild winter. A weak La Nina last winter didn’t produce the expected results in Illinois.

“Last year was an exceptionally quiet winter, with not much snow or precipitation in general,” Angel said.

Overall, the winter temperature trend in Illinois remains on the rise. Average winter temperatures warmed by 1.7 degrees during the past century, according to the linear trend, Angel noted.

Only one of the 10 coldest winters has occurred since 1980 (2013-14). Meanwhile seven of the 10 warmest winters have occurred since 1980, including four of the top 10 warmest winters since 2000, Angel added.