Tricky snowfall forecast for Denver, Colorado Springs, as winter storm arrives tonight

It's cutoff low season, and with that comes a good amount of uncertainty with large storm systems that swing through the Four Corners then into Southeast Colorado and the Texas/Oklahoma panhandles.

These systems are often big snow producers for the Front Range and urban corridor, as they are powerful, often slow-moving systems that can tap ample moisture as they move east of the Rockies and strengthen.

Whether they produce copious amounts of snow for the Front Range or not ultimately depends on the exact track of the low, and of course speed. As we head deeper into March and April temperatures also become an issue, as less and less cold air becomes available.

This particular system looks like it may come up a bit short of its full potential for snowfall. While considerable uncertainty remains, models continue to resolve on the lower-end for snow for the Denver area and points north. Greater snowfall potential is seen across the Palmer Divide, Colorado Springs region, and Southeast Plains.

While we continue to think there is a boom scenario on the table given the track of this low (we discussed this in last night's Insider update), models are in better agreement today that this system may fall short of its full potential, at least across Northeast Colorado.

The main issues are surrounding the lack of cold air, and perhaps a quick shift to downsloping –– especially for areas from downtown Denver or so and points north.

The best window for the Denver to see snow appears to be Sunday morning through early afternoon, as the low emerges east of the mountains and begins to intensify across Southeast Colorado. This is when we see our best upslope flow, with good easterlies at 700mb, and with any luck at all enough cooling to help promote that snowfall. Below is a look at current timing for the precipitation expected, with greatest odds for Denver between 3am and 6pm Sunday:

This matches up pretty well with the latest 3km NAM model. It shows the best conditions for snow along the northern urban corridor Sunday morning, with downsloping winds gradually cutting off snow –– first for Fort Collins, then south into Denver as the day progresses. Across the Palmer Divide and Southeast Plains most of the day looks snowy.

Snowfall totals
If you're hoping for a boom snowfall in Denver or areas north, you're better off not looking at our morning gamblers. They are really not enthusiastic about snow. This is especially true for Fort Collins, where downsloping really may have the upper hand. For Denver and Boulder probabilities aren't impressive either –– however, those trailing high-end probabilities (if low) indicate some uncertainty here, and that a "boom" scenario is in play. Great confidence in several inches of snow from this system exist for Castle Rock, Colorado Springs, and Pueblo:

If we compare these to the Euro probabilities, we see they share a similar idea. From Denver north those probabilities for 3" of snow or more are quite low, while the Palmer Divide and portions of Southeast Colorado see from 40 to 80% probabilities:

The European ensemble mean precipitation forecast shows a sharp cutoff north as well, with 0.4" of liquid across the Palmer Divide, and 0.1 - 0.3" for the Denver metro area, to near-nothing across the Cheyenne Ridge. In the means, Southeast and Southwest Colorado see the greatest numbers, which is exactly the parts of the state the need it most!

We'll go with the following for our snowfall forecast, and update this evening if need be.

  • Fort Collins: Trace - 3"
  • Denver (downtown): Trace - 3"
  • Denver (south): 2 - 5"
  • Palmer Divide: 3 - 8" (Locally 5 - 10")
  • Colorado Springs (north): 3 - 8"
  • Colorado Springs (downtown): 2 - 5"

Impacts
Clearly we expect the worst of the conditions from late tonight through Sunday evening to be across the Palmer Divide. A slight shift in track and that could end up including more areas north or south.

Travel will not be advised across much of Eastern Colorado on Sunday, especially south and east. Snow will be heavy at times and STRONG WINDS will likely cause blizzard conditions –– with low visibility and snowpacked roads forecast.

Snow will be heavy and wet, with temperatures pretty warm with this system.

The window for most of Eastern Colorado will be from midnight tonight through midnight Sunday night, though across far Southeastern Colorado some of that snow could linger into early Monday morning.

Conditions will gradually improve from north to south Sunday.

What to watch for
As we've said time and again, plenty of uncertainty remains. While there's better agreement in the modeling this morning, there's still room for change. As we track the low across the Southwest United States today we'll begin watching for subtle shifts in track and speed vs what models are currently indicating. It's easy to see how a shift north of not-so-many-miles would extend the window of favorable upslope flow for the Denver area and thus increase snow totals. It's also easy to see how this thing misses us south and southeast.

For now our forecast splits the difference a bit. It will be important to check back this evening, as we'll pass along updates if we see a shift in that track and ultimately what that shift means for our snowfall forecast.

Looking ahead
Another trough drops out of the Northern Rockies early in the work week and will keep us cool and unsettled. Not looking like a huge amount of additional snow, but so far this February these disturbances have over delivered. Keep an eye on the forecast as we head into the work week, as much of the remainder of February looks chilly and unsettled after today.