Snowfall looks possible, if not likely, now for this evening through Saturday morning by two impulses that will swing through. The first showers may start near the metro area in just a few hours.
Following Wednesday's initial snowfall discussion we posted for you, we have these specifics to add:
Here is a short animation based on a rapid update model called the HRRR which shouldn't be taken literally but just used as initial guidance on timing and location of seeing the first snowflakes. As of this morning, it shows light snow showers pushing into the Denver/Boulder/Fort Collins area as early as 7 pm:
As suggested, the snow will begin for some folks by this evening and will last a few to several hours into Friday morning. This snowfall is coming from a relatively weak wave moving over Wyoming and Northern Colorado.
Through Friday morning, here are some possible snowfall totals for the area using the GFS and NAM models. Note that both are similar for Denver but heavier snowfall depicted for the mountains on the first image:
Another wave, the parent storm system, swings through later Friday into Saturday morning; this is the impulse that will blanket the Central/Northern Plains and Midwest in freezing rain and heavy snow for the weekend. Locally, unless the system slows down a few hours, the impact will be lower on the scale. Some models have been trying to slow the system down a bit but not convincingly so just yet. If things change today, we'll update the forecast as needed Friday.
Possible accumulation through midday Saturday is shown here, using GFS and NAM again. Note this time that both differ in the location of a band of snowfall for NoCo and differ in the amount of snow coming to the eastern plains.
In a banded snowfall event, as expected late Friday, these models are valuable in that each shows the potential for banded snowfall but lack in accuracy as to where to place that band; something to see as the storm begins and evolves.
The combination of these two impulses creates on and off travel impacts around the metro areas. Here's a look at snowfall chances broken down by hours using Denver as the source:
The timing here can be adjusted 2 hours ahead or behind depending on your exact location.
Historically the similar storm patterns have resulted in snowfall as forecast in the GFS and NAM. Short-range, higher resolution, modeling doesn't disagree with the overall consensus but does suggest the possibility of a snow band covering part of the greater metro area, and the result will be several inches of snow. We shouldn't ignore that indication, and we could also look at some of the higher totals as a possibility considering the strength and location of the system can be snowier than how the models currently depict our snowfall totals for Denver proper.
Snow banding is possible in this event. With that said, we aren't discounting the possibility of a higher end total, but we are going to wait to see if that can happen in the second storm impulse that moves through. With another 24 hours, roughly, of modeling data to digest before any snow band formation with the second round of showers.
Our eyes will be fixed on the data to see how this forecast pans out. Speaking of which, here's the idea we have for numbers at this time:
Our Gambler data indicates the spread in possibilites for those of you who enjoy seeing the kind of spread in snowfall totals that is possible.
If we need to make adjustments following the first potential round, we will do so Friday midday in preparation for the second round.