Matt Makens

We previously posted on the historical perspective of a White Christmas, and now
we look at the forecast which shows a potential system in Colorado Christmas
Day.

Now the pattern isn't exactly solidified and only indicates a low-end chance of
rain and snow in Colorado, but it is a chance.

Historically speaking, here is the probability of a White Christma:



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 be a reasonable probability to use as a prediction this year for many
areas IF you use the 1 inch of snow on the ground definition, however there will
be some melting - quite a bit of it - with very warm temperatures this week.

Here is the snowfield across the US as of Tuesday.



The modeled amount of snow depth remaining by Christmas Day looks like this:



That modeled image indicates the Plains likely to be mostly snow-less again by
Christmas.

If you ask me, a White Christmas needs snow falling to count, or at least the
day before? Historically, we've only seen a trace or more snow fall on Christmas
Day 14% of those on record.

As we look at the odds this year, the ocean-atmosphere teleconnections show the
likelihood of a western US trough with that negative of a PNA index:



Other modeling agree and show the trough to the west in the 500 mb pattern.
Here's a multi-panel view of the GFS, Euro, and Canadian for Christmas morning.



It's clear that the global modeling agree in a trough to the west. That setup is
favorable to at least bring some moisture into the region and state.

The GFS has been most excited about the chance of rain and snow in Colorado for
Christmas. Here's a look, also Christmas morning, at the state and does indicate
some rain and snow albeit not much in the morning, or afternoon.





So, there is a chance of snow Christmas Day - mostly for the western half of the
state - but, it's a chance!

For the metro areas, the chance via our Gamblers Charts is <30% for snow and/or
rain. The GFS is slightly higher, but only slightly so, as is the Euro.

Maybe that's why the Dumb and Dumber character Lloyd had the last name of
Christmas... "So, you're saying there's a chance!"

Christmas weather pattern comes into view with rain and snow chances