Matt Makens

The next system will swing through Sunday night and Monday to bring widespread
travel issues across the region. For the metro areas, snow chances are likely
and accumulations are expected through Monday.

For Denver:

For Colorado Springs:

As you look over those hourly planners, Colorado Springs stands a higher chance
of rain initially before a snow changeover, however, it is pretty early yet to
be getting too specific on that timing.

When it comes to timing, data through Friday morning indicate a low-end amount
of snow on the ground by Monday morning for the metro areas, with most
accumulations to happen during daylight hours Monday. Of course those details
may shift too.

Here's the latest NAM "radar" animation showing the system move across the
western US midday Saturday through late Monday afternoon. 

And, let's look at the upper-level slices from GEFS and ENS. The times are the
same, 5pm Monday. 

The GEFS is a bit faster and a touch north, but not too far north as to limit
the precipitation into Colorado as we will see with our operational GFS image
below. I

Based on that systems track, the biggest impact to travelers will be the
mountains, Wyoming, and Nebraska. With that in mind, let's take a look at a
couple of model estimated snowfalls, the first is the GFS - which emphasises
those travel issue areas, but perhaps doesn't do enough to Colorado.

I find it hard to believe that the GFS projection with such little snowfall over
the metro areas will verify given a blended consensus of a storm track right
overhead with several hours of potential precipitation. The GEFS mean
precipitation is much higher than that of the GFS, into the 0.25-0.5" ranges and
that certainly going to produce the potential for heavier snowfall than what
that operational GFS shows. 

Here are our snowfall probabilities updated Friday morning, and using 13:1 as
the ratio. 

More in line with our thinking, and probabilities above, is the Euro Ensemble,
which may be a bit low also considering the moisture potential. The placement of
the totals does feel more reasonable, aside from bringing some of the higher
totals from Northeastern Colorado farther south and west. Another detail to work
out this weekend.

Like we saw with our last system, models only hinted at big totals until very
near the arrival of that storm. Considering the river of moisture across the
western U.S. remains strong, and recent history, I think we should approach this
event more cautiously with at least some potential of higher totals ahead versus
what is indicated at this time - we shall see.

This video discusses the West's incredibly wet pattern through Sunday. A future
video will focus on the storm in this particular blog.

Colorado weather: Snow targets the New Year across mountains and metro areas