Dreaming of a white Christmas? Dream on

Sunday, December 20, 2015

With temperatures poised to possibly hit the 60-degree mark on Christmas Day this Friday, there seems little chance for a white Christmas this year in central Indiana.

And actually, that is the case about half the time in this area.

There are several ways to define a White Christmas. For the purposes of the historical look back, the National Weather Service (NWS) includes a white Christmas as any day that has either at least a trace of snow on the ground, or experiences at least a trace of snow falling that day. In more general terms, it defines a white Christmas as any Dec. 25 that central Indiana sees snow.

So what is the chance of at least a trace of snow falling at Indianapolis on Christmas Day? Well, snowfall records on Christmas Day have been kept in the Indianapolis area since 1871. And in that 144-year period of record, a trace of snow (or more) has fallen 66 times. This could be equated to a 46 percent chance of at least a trace of snow falling on Christmas Day.

The other possibility for a white Christmas would be if at least a trace of snow was already on the ground. That could be old snow from a week ago, or just the day before.

Snow depth records don't go quite as far back, having been started in 1896. And in that 119-year span, there has been at least a trace of snow on the ground on Christmas Day a total of 58 times. That equates to a 49 percent chance of at least a trace of snow on the ground on Christmas Day.

The last Christmas that saw snow on the ground in central Indiana was in 2012, with a trace of snow on the ground. Near-blizzard conditions arrived the following day, however, producing 7.5 inches of snow at the Indianapolis airport.

On Christmas 2010, five inches of snow was on the ground Christmas morning. (Remember that December was the third-snowiest on record in Indiana with 16.6 inches).

So what would the probability be of having either a trace or more of snow falling or a trace or more already on the ground?

Since 1871, that has happened in a total of 84 times, where either the snow has fallen or already has been on the ground.

That amounts to an overall probability of just below 60 percent that Putnam County will see either some snow falling or some snow already on the ground on a typical Christmas Day.

Just not this year. Apparently. Perhaps. Maybe.

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