Models Coming into Reasonable Agreement on Snow this Weekend

In our update last night we outlined that our next storm system could bring measurable snowfall to the Denver area by late this weekend. If it does, it’ll be the first measurable snowfall in Denver in nearly a month!

We continue to like the general look of this storm. Outside of being long overdue for snow, this setup appears to have many of the right tools in its toolbox to deliver; the big question is -- can we maintain this look over the next four days? We’re still a ways out, all things considered.

What we’ve seen today is better agreement among the GFS/GEM/EURO operational and ensemble models for the forecast track of the upper level low. We are also seeing better agreement on timing, with models producing the best upslope for Denver from Sunday afternoon through Sunday evening before diminishing early Monday. Lastly, we’ve seen all three models move to focus the heaviest snowfall slightly further north compared to yesterday’s 12z run, as we suggested may happen last night.

Take a look at this image which shows a comparison of the GFS/GEM/EURO operational and ensemble runs. Note the fairly good agreement among the three and their ensembles. There remain subtle differences between placement of the surface low by Sunday afternoon, which translate into noticeable differences in where the heaviest snow bands may set up. The slightly more northern solutions will support a better chance for heavier snow across northern Colorado, a more southern solution over southern Colorado.


Our system is moving inland today and tonight as seen in this IR imagery below. It’s packing a LOT of moisture tapping into the “Pineapple Express” to bring California several inches of rain and feet of snow at higher elevations over the coming days.

Environment Canada

By the time it reaches Colorado it’ll still be carrying plenty of moisture. It won’t be particularly cold system, though in terms of moisture some models try to enhance precipitation by tapping into the Gulf of Mexico as well. In fact, the southeast plains of Colorado may even see things start as rain before changing to snow, atypical for a December system. At this time, it appears as though the biggest questions remaining with this system are focused around its precise track; a reminder that a deviation of just a hundred miles often means the difference of no snow and several inches.

It’s too early to be putting out snowfall forecasts. Models are ranging from 1” to 10”+ for Denver. The Canadian has a nice compromise and would suggest a 3 - 6” snowstorm for the Denver area, with pockets of heavier totals across the eastern Plains. The ECMWF is painting the heaviest snowfall from DIA east, and the GFS is… well, somewhere on the lower end. That being said, I can almost guarantee we’ll see all of these models flip a few more times between now and Sunday, so again, refrain from getting too attached to specific numbers.

More importantly, know that this system has the potential to bring the highest impact event of the season to the Plains by Sunday, so please plan accordingly, and stay tuned for all the latest updates on the storm!

Brendan Heberton

Brendan is founder of Weather5280. He is co-founder of FreshyMap, and develops software for geospatial data analysis and visualization.

Denver, Colorado
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