Now on Tuesday morning at 700am, as I write this, we have a snowstorm on our hands. The radar is active, showing lots of snow falling across Wyoming and northern Colorado.

And there is snow on the ground with a coating showing up on the Cameron Pass CDOT cam (northeastern mountains).

The forecast for colder temperatures and snow have come true, and some mountains will likely see double-digit accumulations by Wednesday morning.

However, the more westward track of the storm has me worried that the steadiest and most intense snow will be confined to a shorter time period on Tuesday afternoon and Tuesday evening and will focus on fewer mountains.

If you are looking to make turns on high-elevation grassy slopes, I am not sure that there will be enough snow by Tuesday late afternoon, and the better chance will likely be on Wednesday morning at sunrise near and east of the divide.

I was a little worried about this shift in the forecast when I wrote Monday's post, but all models still advertised a lot of snow for many areas and it's hard to go against a model consensus.

But now on Tuesday morning, with the benefit of having real-time data and comparing actual snow totals over the northeastern mountains (< 1 inch, somewhat due to a warm ground) to forecasted totals across the northeastern mountains (4-5 inches), I think that the models are being too generous converting light precipitation into significant snowfall when it'll take intense precipitation to make significant snowfall.

With the storm center tracking far to the west, we can't rely on energy from the center of the storm to bring us significant snow. So we'll rely on energy from the jet stream to create bands of intense snow, and this jet stream energy might only show up intermittently.

Let's look at the precipitation forecast for Tuesday and Tuesday night. The areas in green are places where we could see significant precipitation and I circled these areas in blue.

Tuesday at 500am. Mostly light precipitation (brown colors).

Tuesday at 900am. Significant snow over the northeast and northwest mountains begins.

Tuesday at 1200pm (noon). Notice how the significant precipitation over the northeastern mountains from 900am wanes by this time and instead a band sets up over the far northwestern mountains.

Tuesday at 300pm. This is when the jet stream energy moves over the southeastern mountains and an intense area of snow develops from near Wolf Creek to near Monarch. Also, some energy on the northern edge of the storm brings precipitation to northwestern Colorado.

Tuesday at 600pm. That jet stream energy continues to produce significant snow from near Wolf Creek northeast through the front-range foothills and mountains and likely includes the Denver metro area.

Tuesday at 900pm. Intense snow may continue over the eastern mountains, foothills, and cities.

Wednesday at 1200am (midnight). The intense snow has pushed east of most mountains, hanging on for the Sangre de Cristo and Wet Mountains.

For the rest of late Tuesday night through Wednesday, there will continue to be bursts of intense snow and rain, especially over the southwestern mountains (San Juans), though accumulations look random, anything from 'not much more' to 'many more inches' under the most intense showers.

To sum up, my expectations for significant snow by Tuesday mid-afternoon are lower, but the burst of snow starting Tuesday afternoon through about Tuesday at midnight should mean that many mountains in the eastern half of Colorado should still see decent snow totals by Wednesday morning with a few spots maybe getting to double digits. Areas near I-70 and south, and areas near the divide and east, have the best chance for the deeper snow totals.

Again, the reason for the late shift in the forecast is the farther west movement of the storm. Since the system won't take a direct track over Colorado, which would lead to more consistent precipitation over a long time, we are relying on the jet stream energy to create a narrow window for the best chance for snowfall.

I always hesitate to write these last-minute adjustments as I don't like to flip-flop the forecast, but it is worth making adjustments to expectations based on forecast model updates AND when we can understand why these adjustments are happening (versus blindly following the latest model).

In this case, the models have shifted the most intense snow to Tuesday afternoon and Tuesday evening, and we understand why this shift is occurring because this is when the best jet stream energy will move across the state.

Thanks for reading!

JOEL GRATZ