Chicago's White Christmas dreams fading fast
Chicago - To say that the first half of December has been remarkable in terms of temperatures is putting it mildly. No pun intended.
Every day this December has been above average. So far for the month, Chicago is running nearly 6 degrees above average. If December stopped today, it would be at least the 5th warmest on record.
While we have a few fluctuations in our temperatures over the remainder of the month still coming, it is obvious at this point that the month will end up unseasonably mild overall.
Today's high is closer to what we expect at the beginning of November. Our high should be between 15 and 20 degrees above average. Nine of the next ten days will have highs above average according to our Fox Model.
Monday's high of 32 would be the only day below average, falling short by about 4 degrees. Next Monday, Tuesday, and Friday could be cold enough to support snow, especially during the overnight periods. The hope for any substantial snow on the ground hanging around into the morning of the 25th to qualify for a white Christmas fades fast with highs the weekend prior to the holiday climbing into the 40s.
In a previous post, I discussed the historical probabilities of a white Christmas here. The chances range from 25% to nearly 50% depending on your exact location in northern Illinois and Indiana. The higher probabilities can be found the farther north and west of the city with the lower probabilities the further south. Chicago has around a 35% to 37% chance of having at least one inch of snow on the ground Christmas morning, the minimum required for a white Christmas. Check out NOAA's interactive map to find the probability for your location.
The longer-range temperature outlooks from the Climate Prediction Center correlate with our Fox Model extended forecast. The maps are ablaze with orange, red, and brown colors that designate areas of the country favored to be above average overall.
The 6-10 day temperature outlook forecasts northern Illinois and Indiana to be "likely above" normal overall. This covers the period from next Wednesday through Christmas Eve. Average highs during this span are around 34 to 35 degrees. The only portion of the country forecast to be below average overall is a relatively small slice of the southeast.
The 8-14 day temperature outlook keeps the mild pattern coming. We are again expected to be "likely above" normal overall with even higher probabilities than predicted in the 6-10 day outlook. This longer-range forecast covers the period from next Friday through the following Thursday.
The impact of climate change on December's temperatures is making it tougher to squeeze out enough snow for a white Christmas. Climate Central's study of the change in average temperature for December shows most of the country is experiencing milder Decembers now compared to 1970. They studied 244 cities and the average temperature for the month has jumped by about 2 degrees above normal over the last half-century.
Chicago's average December temperature has increased by 1.4 degrees according to the analysis. Warmer temperatures mean more precipitation falls in the form of rain rather than snow. That reduces our chances of seeing a white Christmas.
Looking even further into the future, the period from Dec. 25 through Jan. 5 has shown even more substantial warming. This timeframe is featured in a popular Christmas Carol. Join me now in song - on the 12th day of Christmas (and the eleven other days too) Chicago gave to us, a warmer pattern compared to average. It doesn't flow smoothly as far as song lyrics go, but you get the point. According to another Climate Central study, the 12 days of Christmas have warmed by nearly 6 degrees over the past half-century.
The 3-4 week temperature outlook aligns fairly close to the 12 days of Christmas period. Once again, we are favored for above average temperatures overall. This forecast covers the period from two days before Christmas to four days after the start of the new year.