Matt Makens

The odds of a White Christmas remain near the 30-year average as there's little
to support a stormy pattern for the week before Christmas across the metro
areas.

Here is the climatological probability of a White Christmas:


There is a 40-50% probability for most of the metro areas by this definition of
having at least 1 inch of snow on the ground.

That may even be higher than the reasonable probability to use as a prediction
this year.

I'll start with the hope, which is within the CFS model, by showing a bit of a
negative PNA index a few days before Christmas, and that indicates a westerly
flow over Colorado.



Within a westerly flow, we can easily have a shortwave move through to drop some
snow. However, the downer here is that all other indices are positive, and that
indicates a rapid flow and a warm one.

Let's look elsewhere. Based on the current pattern and how it compares to those
of the past, there is a high unlikelihood for snow for the week leading into
Christmas. The statistics in this regard remain much drier and warmer than
average for that week for those near and east of the mountains.





So, that's a further negative for snow lovers.

Since we are discussing the chance of a White Christmas by the 1 inch on the
ground definition, is it possible this week can bring enough snow to sit around
through the second week into Christmas? Looking at the GENS snowfall through
Christmas morning, there's a lot of snow on the way for some, but few in the
metro areas.



The snow chances on the way in the next few days that produce the accumulation
shown over Denver, Fort Collins, Colorado Springs, etc. probably don't last into
Christmas week. The snow depth number of the GENS (not snowfall, snow depth)
decreases to 0 inches well before we reach Christmas Day.

Granted, it's the GENS. However, it doesn't look much different in the Euro.

So, those dreaming of a White Christmas need to cross their fingers for a potent
short wave within our westerly flow.

Odds of a White Christmas