Colorado Weather Discussion #143: Nov. 11, 2021

Snow totals so far, and a look at tonight's final wave of snow.

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Updated Thu Nov 11, 2021 5:30pm MST | Published Thu Nov 11, 2021

By Thomas Horner

Snow Totals and Forecast Verification So Far

Last updated .

Forecast Start:

Forecast End:

* = No reliable observations, verification uses SNODAS estimates which may be incorrect.
"Score" accounts for the spread/range of an accurate forecast. Lower spread = higher score. For instance, if 4" falls at a certain location, the forecast for 2-7" gets less points than the forecast for 3-5". Points are deducted for very inaccurate forecasts.

Retrospective Discussion

A trough entered our region on Tuesday and kicked off several days of snow in the Colorado mountains. This system underwent lee cyclogenesis as it crossed east of the Rockies, and a powerful center of low pressure is now spinning over Minnesota.

(via College of DuPage)
(via College of DuPage)

Tuesday Night

Our first night of snowfall was about as expected. Western Colorado got walloped with a strong wave of snow, while the eastern Colorado mountains picked up only scraps. Our forecast generally called for 2-9” in the western ranges and 1-4” in the eastern ranges.

That was a good call, but as always, there were some surprising totals, such as a cool 5” for Crested Butte and Loveland managing to sneak in 4”.

Wednesday Night

Wednesday night was unexpectedly productive. As the system tracked over the northern Rockies, it slowed a bit more than models had predicted and tracked a bit further south. This was enough to put significantly deeper moisture and better large-scale dynamics over northern Colorado for several hours.

The end result was a bonus shot of 3-7” of snow for many northern Colorado mountains…and Crested Butte, somehow. (Analysis did show a tiny pocket of deep moisture push into south/central Colorado, which was likely responsible for that).

The Park Range missed out on most of this action as the best jet dynamics were located a bit further south. Right now, the Park Range is sitting at where we thought the storm would be right now – quite a few inches short, which is a good situation for tonight’s round of decent snowfall.

Elsewhere, in Summit County and Eagle County, this storm is already looking to bust high and unless tonight ends up being a complete dud, our forecast looks to have been much too low for these areas. Otherwise, we’ve done pretty well in southern, central, and far northern Colorado, though we are a bit concerned about Cameron Pass.

Winds

RTMA has analyzed gusts of over 75mph along the east side of the Divide.

(via WeatherBell)
(via WeatherBell)

These will continue into Friday afternoon.

Tonight’s Snowfall

Snowfall (and winds) have ramped up this afternoon as another wave of moisture and stronger northwest flow aloft enters Colorado. We’re on track for another 2-7” for many northern Colorado mountains, with only a couple inches for central Colorado.

The Park Range should finally enter our forecast range as they pick up many hours of cold northwest flow with decent snow-liquid ratios. It looks like Buffalo Pass has picked up well over 6” of snow since this morning, though the Steamboat snow stake camera is still not showing anything impressive.

Overall, we’re looking at a weak shortwave wrapping around the system to our east to provide a burst of lifting energy and stronger upslope winds tonight, which will tap into deeper moisture. Though good moisture sticks around into Saturday, we enter a region of strong upper-level subsidence by Friday afternoon, which will limit snow production by upslope winds.

Snow still looks to mainly wrap up by 5am, with lingering light snow in the northern mountains into the afternoon and a weak disturbance on Saturday.

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