Winter Weather Update: A southern-track winter storm will bring snow/wind to parts of eastern Colorado Thursday, but uncertainty lingers for our immediate area

A medium-impact winter storm is headed for eastern Colorado, bringing some snowfall and strong winds to parts of the Denver Metro area late Wednesday night into Thursday afternoon. Weather models show varying predictions, but the southern and southeast suburbs of Denver are favored most for up to a couple inches of snow, with higher totals possible along and east of the Palmer Divide. We discuss the rift in the model guidance that is leading to the uncertainty, as well as the latest timing and most likely outcome from this somewhat warmer southern-track winter storm.

At a Glance

• Current Storm Status: A cut-off low pressure system is currently located in central Arizona and is expected to move into southeast Colorado Wednesday night into Thursday where it will tap into Gulf of Mexico moisture
• Weather Model Rift: There is a discrepancy between global and short-range weather models regarding the storm’s impact on the Denver area. Global models suggest the heaviest snowfall will remain southeast of Denver, while short-range models indicate a closer approach
• Snowfall Amounts: The southern and southeast suburbs of Denver, including Centennial, Parker, and southeast Aurora, have the best chance to see up to a few inches of snow. The highest totals, possibly exceeding 6 inches, are expected along the Palmer Divide and areas east of there. Boulder is expected to receive little to no snow from this event.
• Uncertainty Lingers: Even this late in the game, there is still considerable uncertainty regarding the exact track and impact of the storm on our region. The northwestern extent of the heavy snow bands will need to be closely monitored for commute impacts Thursday A.M.

Now the southeast Metro area is favored?

ll eyes are on the approaching storm system still spinning to our southwest Wednesday morning, currently located across central Arizona but slowly meandering eastward. The cut-off low pressure doesn’t look that impressive at all on GOES water vapor imagery which speaks to the lack of moisture associated with this low for now — it’s barely generating any precipitation at the moment. That will change as the storm makes its way eastward and begins to tap into Gulf of America Mexico moisture tonight through Thursday.

Models are in strong agreement, as they have been the last few days, that the cut-off low will move east-northeast into the southeast corner of Colorado late Wednesday night into Thursday morning, strengthening in the process.

As the low pressure wraps up across southeast Colorado and western Kansas, a plume of Gulf of America Mexico moisture (known as the warm conveyor belt) will wrap back into northeast Colorado giving this system a bit of life and potential to produce rain/snow across eastern Colorado on Thursday!

A very narrow deformation zone will aid in producing a strong area of lift just south and east of Denver late Wednesday night into Thursday. Notice how the band of precipitation in the simulated radar animation below moves into the Denver area tonight and then stalls for hours — this is a textbook example, albeit a narrow one, or a deformation zone causing a band of concentrated lift to form precipitation.

Where exactly this deformation zone sets up will determine who gets basically nothing versus who gets several inches of wet snow. The global models have been consistently showing this stalled band of precipitation remaining well southeast of the Denver Metro area, as shown in the two upper panels below (Euro/GFS forecasts). However, since the short-range models have gotten a look at this storm yesterday, they have been indicating a much closer approach to the Denver area, shown in the two bottom panels below. It’s hard to say what exactly is causing this large disconnect in the modeling, as track alone cannot explain this shift of 100+ miles with the core of the heaviest snowfall. Most likely there is some type of terrain interaction with the low-level winds, which altogether is still uncertain and will steer the ultimate resting place of the snowy deformation zone.

A potential “worst case scenario” from this system is shown by latest run of the HRRR from Wednesday morning which generates a wintry swath of 5 to 11 inches of snow southeast of Denver, but one heck of a gradient heading northwest towards Boulder. Every mile of track variation with the passing low pressure will really count!

Ultimately, we believe the short-range models are misguided a bit right now, and will trend our forecast towards the global solutions which are backed by strong ensemble support. That is, we expect most of the snowfall (including heavy snow) will stay largely southeast of the Denver Metro area. The southern and southeast suburbs will stand the best chance to see a couple inches of snow accumulation (Centennial, Parker, southeast Aurora), with the highest totals expected on the far eastern extent of the Palmer Divide which could be in excess of 6 inches. Our snowfall forecast map for the event is shown below covering all snow through Thursday evening. Boulder and the northwestern Front Range can expect anywhere from nothing to 2 inches. Up to 4 inches of snow may accumulate on the southeast side. However, confidence is somewhat low in the overall forecast as of writing, but from experience, this type of setup will more often than not trend towards the southeast solutions.

Our general forecast thinking matches up closely with the current batch of Winter Weather Advisories posted by the National Weather Service which include the Palmer Divide and Plains areas southeast of Denver.

Unlike our last few snowstorms which were laced with bitter cold air, this event will be lacking on that front. While there should be no issues getting cold enough for frozen precipitation in the core of the heaviest snow bands southeast of Denver, the fringe areas to the east and north may see some rain mix in. At the very least, this storm will have a wetter snow than recent events, with snow ratios between 10:1 and 15:1 — in locations that actually see snow that is!

Here’s the storm timeline:

• Wednesday: Sunny skies most of the day, but with clouds increasing during the evening. Highs in the 40s again. Everyone stays dry.
• Wednesday night: Bands of snow will move into the area from the southeast overnight, mainly impacting locations southeast of Denver. Minimal to no snow is expected in Boulder overnight.
• Thursday: Bands of snow will be around Thursday morning, mainly southeast of Denver. Some snow may be heavy at times. Strong north winds gusting over 30 MPH and snow may produce difficult travel on I-25 south of Denver and I-70 heading east. The morning hours will offer the best chance of snow in the Boulder-Denver area, but things should be low impact and light. Snow ends around midday with sunshine taking over in the afternoon. Gusty north winds of 20-30 MPH will occur in the afternoon/evening. Highs once again in the 40s.
• Friday: Dry and pleasant with temperatures warming up further to near 50 degrees.

NowCAST has mainly just a low chance for light snow in Boulder Thursday morning, with sunshine and gusty winds by afternoon:

Unsurprisingly, NowCAST is telling a different story for Thursday in Centennial, with a much better and longer timeframe for accumulating snow. Locations south and east of Denver could have a slick morning commute on Thursday!

As discussed already, there’s still a decent amount of uncertainty with this event regarding the threat of heavy snow and exactly how far north and west it will reach. We’ll pass along any prudent updates on social media if things drastically shift later today. Come join us on Twitter, Bluesky, Facebook, and  Threads for impromptu weather updates as this “snowstorm” unfolds, or subscribe to get notified of our long-form updates here.

Think snow!

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BoulderCAST Team

This post had major contributions from at least two members of our team. The more meteorologists the better, right?

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