If you are a model watcher, and we know many of you are, you have no doubt watched snow for Denver in one model run and then it's gone. And then, it's back. And, so on. That's the pattern we are in and is usual for those times when the Pineapple Express is actively bringing moisture into our region. With that said, Sunday night and Monday's snow chance has been persistent and likely to pan out.
The Pineapple Express is a moisture-laden flow from Hawaii (this time it originates well beyond Hawaii), which is quite easy to spot on satellite imagery like this, although I did draw the red arrow on this RAMMB image for quick assistance:
When we have a steady flow of moisture like this we see healthy snowfall totals coming from the mountains, which we have indeed measured recently. For Denver and metro areas, there still needs to be a strong frontal passage and/or an upper-level feature to create enough lift for snowfall to form. Thursday afternoon's frontal passage wasn't enough to do the trick, but what's coming late this weekend and early in the week may do the trick.
The middle atmosphere is quite active with lots of storm systems circling the Northern Hemisphere. Here I've colored the most energetic waves in deeper reds...
This active frequency is what has kept our weather relatively unsettled of late, and that will continue for quite a while it appears as those 'energized areas' continue to circle the pole.
Energy in the middle atmosphere is diving out of Canada this weekend (the long red areas from southwestern Canada pointing toward Hawaii on the image above) and may place a trough to our northwest in just the right location to deliver lift.
This energy will also be pushing colder air into the region, too.
That combination, including the steady moisture flow previously discussed, should be enough to once again bring measurable snowfall to the Denver area.
Historically, the pattern has produced a median snowfall within the range of 0 to 3" to the metro areas (also a juicy bullseye to Southwestern Colorado):
The probabilities of a similar event this time? Well, a run of the Gambler shows it is possible:
Looking at a larger scale, we see the pattern over the next three days generally favors areas west of I-25 and south. Models like the idea that Colorado Springs could see several inches before all is said and done, as well as Boulder and Castle Rock... while Denver/Fort Collins those probabilities are a bit lower overall:
Just looking at the NAM, GFS, and Euro modeling Saturday morning we see a spread of possible solutions for the metro areas but every one of them brings some snow through Monday evening:
With all of this in mind, here's what we are thinking for snowfall totals through Monday evening. Note that some models have an additional push of snow moving through Monday into Tuesday, but we'll wait to see how things look in another day or so before worry about that. This map includes today's snow showers, and any snow we might see Sunday and Monday (we have some internal discussion about snow ratios and may need to adjust this map in Sunday's SOTA if we see the need in Saturday's data):
Timing and impacts
Again, we're looking at off and on snow chances over the next several days, so snow totals we're discussing are in total between today and Monday evening.
We see the first batch of snow showers move through Saturday afternoon, with best chances along and south of the Palmer Divide. Totals today are expected to range from 0 - 2", with most areas north of C-470 closer to the lower end range here. Not everyone sees snow today.
Sunday we see the next chance of snow arrive to the I-25 corridor. Here we could see better snowfall as we head from Sunday into Monday, though totals overall look light. Best chance of snow Sunday into Monday looks to be along and west of I-25 across northern Colorado, then perhaps better coverage across the Palmer Divide, through Colorado Springs, and across the Southeast Plains.
As temperatures continue to tumble to end the weekend and start the week, any snow that does fall will make for some slick spots on the roads. Again, we expect off and on snow showers over the next three days, so not a single snow event to focus on at this time.
A reminder, you can follow our daily forecast here.
Regardless of snowfall (or lack thereof in some spots), we do have cold air moving in. Denver to measure single digit lows to start off the week. You can see that cold air moving in below, and it'll stick around for awhile:
So, plan on some colder air working its way into eastern Colorado today as well as some snow showers as we head into Saturday evening. We'll see those snow chances return on Sunday (perhaps a bit better chances for some) and will update as needed in Sunday's SOTA.