Will December's Warmth Limit Our Chance of Seeing a White Christmas?

It's a question that gets asked once we enter into the month of December.  'Will we see a White Christmas this year'.  And with one of the strongest El Niño events shaping up this winter, you may be wondering if there will be any snow for when you travel over the hills and through the woods.

Chance of a White Christmas in any year, based on data from 1981-2010
Climate.gov

Meteorologists define a White Christmas as having at least one inch of snow on the ground on Christmas morning.  Now you may be thinking that should be easy, right?  Well, not necessarily.  A White Christmas isn't as common as you may think - even for the snowier cities and colder climates.  Just take a look at the image to the left.  Cities in the north that are usually cold and snowy have a slightly less than 100% chance for a White Christmas.  Impressive, isn't it?  In northern Illinois and southern Wisconsin, our chance - based on historical data - would suggest we have roughly a 40-50% chance of seeing a White Christmas.

When we look at El Niño, it's important to realize that this isn't going to be the sole driving force for our weather this winter.  Yes, it will be a major factor.  But there are other atmospheric circulations and patterns taking place that could also have an impact on the 2015/2016 winter season.  For example, the NAO (North Atlantic Oscillation).  This is one of the most prominent teleconnection patterns during all four seasons.  It consists of a positive and negative phase, each of which has an influence on temperatures and precipitation across the globe.  This could lock in a cold pattern across parts of the U.S. regardless of whether or not we're in a strong El Niño. 

NOAA Climate.gov

The winters of 1982/83 and 1997/98 were very warm in northern Illinois and southern Wisconsin.  However, even during strong El Niño winter seasons of '57/58, '65/66 and '72/73 temperatures were near average, or slightly cooler than average.  An indication that some other atmospheric influence was at play.

It's important to remember that the variability in day-to-day and week-to-week weather can still bring a strong snowstorm even in a location where a season long El Niño would otherwise work against it.  Just think of the foot of snow that fell a couple weeks ago.  Just because we're in an El Niño pattern doesn't mean we won't see snow.  While the likelihood of below average snowfall is high, get another major snowstorm to roll through and that could change everything.