Updated Sunday, Sep. 6 to add National Weather Service winter weather alerts.
A powerful early season wintry storm could cover parts of the Rockies in several inches of snowfall just as the long Labor Day weekend ends. The storm will be preceded by record or near-record high temperatures in the 90s Sunday and Labor Day, along with extreme fire-weather conditions.
The drastic change in the weather will occur early Tuesday. Temperatures will plummet behind a strong cold front Monday night, with rain and wet snow developing, from western Montana to Wyoming and Colorado.
Snow levels will drop quickly, and accumulating snowfall is likely across the mountains and foothills of the Rockies. Most of the accumulating snow will be over the higher terrain and foothills, with a chance of some snow possible along the Interstate 25 and 70 corridors in the Denver metropolitan area.
Matt Makens, meteorologist at KDVR-TV in Denver, tweeted that Denver has not had a measurable September snowfall (at least one-tenth of an inch) since 2000. The earliest date on record for Denver’s first measurable snowfall was Sep. 3, 1961, when 4.2 inches piled up. The average date of Denver’s first snowfall is Oct. 18, according to the National Weather Service (NWS).
It’s hard to tell at this point how much snow the upcoming storm will produce, but computer models and initial NWS forecasts show 6 to 12 inches in the high elevations west of Denver, as well as in parts of the Wyoming and Montana Rockies. Denver could see 3 to 6 inches. The NWS has issued winter storm watches and winter weather advisories for many of these areas.
Most of the snow will likely not accumulate on major highways because road temperatures will remain above freezing. However, conditions will become slippery and slushy. Colorado’s chain law went into effect on Sept. 1. Click here for more information.
Record lows in the teens and 20s are possible across the Rockies by early Wednesday, which may lead to black ice on some roads. Tree limbs and power lines may buckle under the weight of the snow, resulting in power outages and possible roadblocks.
As of Saturday morning, the NWS had not issued any winter storm watches for the region, but this may change soon.