ROANOKE, Va. – It’s now less than two weeks until Christmas, and the questions have started pouring in. “Are we going to have a White Christmas this year?”
Let’s face it...I started getting that question after Thanksgiving dinner. While it’s virtually impossible to nail down a specific storm two weeks away, there are some steps we can take to diagnose whether or not a White Christmas will happen.
Definition
According to the American Meteorological Society, a White Christmas is defined as an inch of snow or more on the ground on Christmas Day.
Historical Odds
By that definition, the odds of a White Christmas are not that great. Typically, it happens once every 10 to 20 years around here.
Broken down to more of a local scale, it happens more often in the mountains and less often in Lynchburg or Southside. No surprises there, right?
What about this year?
There are a few things we look for when forecasting one-to-two weeks in advance, understanding that specifics are very hard to come by.
One thing we look at is the North Atlantic Oscillation (NAO). This essentially shows us how strong or weak the wind is in the North Atlantic. The stronger the wind is there, the more the cold air is bottled up north. The weaker the wind is there, the more likely you are to see colder air and storm systems dip into the Southeastern U.S.
When you take an average of forecast data (blue line below), the NAO is close to neutral. This means there’s nothing really eye-popping about the overall weather pattern around Christmas.
This map, produced by WeatherBell, shows an average of forecast data but in map form.
What this shows below is more of a west-to-east oriented pattern thousands of feet above us. This typically translates to mundane, if not warmer than average weather.
There’s no obvious blob of warm air over the northeastern Pacific either, which, if it were there, would indicate a colder, more active storm track here.
At the moment, based both off historical and forecast trends, a White Christmas is unlikely in our area. Two weeks out, that may still change. That’s just where we stand right now. Stay with Your Local Weather Authority for updates over the next two weeks.