A Chicago Perspective on Meteorology
In November, the first seven days of the month featured average temperatures that were nearly 12 degrees above normal. Climate records dating back to 1871 indicate that this period was the fourth-warmest week ever in Chicago for those dates. We even slipped in three consecutive days of 100 percent sunshine in a month where the average is 45 percent, the lowest of any month. It’s nice having September in November, especially when there is baseball.
Not only did the Cubs make it to the World Series, but won a thrilling game seven in Cleveland in nearly 70-degree weather. It would be wrong not to point out that the 17-minute rain delay at the end of the ninth inning helped end a 108-year (baseball) drought. Talk about efficient rainfall.
But having September in November cannot last forever, at least not into December. Yes, the month where we see the darkness of the winter solstice brightened by holiday lights is the month that typically brings winter to our doorsteps. It can also bring newly transplanted Chicagoans to their knees if they have never experienced a true “Chicago winter”, kind of like the winters some remember in 1977-79 and more recently from 2013-14. Chicagoans love to talk to each other about how much we hate long, cold and snowy winters, but never really seem to complain to people in California, Texas or Florida. In passing conversations on the phone or Facebook posts, we pontificate about our ability to stand up to the elements and openly profess that the weather is never really as it seems on the national news or The Weather Channel.
A lot of people are beginning to like these warm Octobers and Novembers because they love to continue to ride their bikes, play golf and walk their dogs along the beaches in Evanston and Rogers Park without worrying about cleaning dog paws of snow, salt and who knows what else is in-between their furry pads.
Many also enjoy the first snow, usually that quick shot of one to two inches a week before or after Thanksgiving. Last year, our heaviest snowfall was the Friday before Thanksgiving. The El Nino-driven winter of 2015-2016 was pretty much what most climate scientists and meteorologists expected. We’ve seen patterns like this before. 1998 and 1982 brought very strong El Nino-related weather events into the Midwest, keeping Arctic air and persistent snowfall several thousand miles to the north.
However, more recent studies of strong El Ninos indicate that although Midwest winters tend to be warmer than normal with less Arctic air, that does not inhibit the development of large snowstorms capable of producing very heavy, wet,snowfall at either the beginning or end of the winter season. Warmer temperatures enhance the ability of the atmosphere to hold more water vapor. If the right circumstances play out, strong El Nino winters typically are characterized by fewer days of snowfall and fewer days of Arctic cold (the below zero stuff), but it does not protect us from the occasional 12 inches of heavy, wet snowfall.
The winter of 2016-2017 promises to be quite different, though. The strong El Nino of the last 15 to 18 months has shifted to a now neutral La Nina. This simply means that above normal sea-surface temperatures in the equatorial Pacific have cooled to near and slightly below normal. This pattern has created weeks of heavy rains and mountain snows in British Columbia and the Pacific Northwest, and resulted in above-average temperatures in the northern Plains and upper Midwest in October and early November.
Long-term trends of neutral La Ninas typically create near-normal winters in the upper Midwest and Great Lakes. The recent warmth will likely be replaced by more typical Chicago weather in early December and quite possibly very cold temperatures by mid-December. Past transitions from strong El Ninos to even neutral La Nina’s have resulted in 35 to 40 inches of annual snowfall and eight to 12 days of sub-zero temperatures across the winter. However, other atmospheric conditions can affect the actual winter weather, so never base expectations of the winter from a long-term forecast in early November.
Whether we enjoy winter-specific activities like cross-country skiing or remain inside counting the days to the vernal equinox, we might as well face it and enjoy the winter season. The Chicagoland area has many things to do once the snow begins to fly and the temperature falls below freezing. Several park districts construct outdoor skating rinks for both the casual skater and the wannabe Chicago Blackhawks.
So while we try really hard not to put our bikes and golf clubs away and hope and pray that maybe this is the year the vernal equinox will don a March-in-February disguise, we still need to realize that keeping our bodies physically active will help our minds remain reasonably rejuvenated. If we get tired of the shovels and the skis and the skates and the cleaning of the salt from our dog’s paws, we can always re-watch the DVR of game seven, when it was September and October in November on one glorious night on the shores of Lake Erie.
Rick DiMaio is a professional meteorologist and climate scientist, specializing in aviation meteorology and environmental sustainability. Since 1985, DiMaio has served the Chicago area as a TV and radio broadcast meteorologist, college instructor and flight operations aviation meteorologist.