Colorado Weather Forecast #146: Nov. 20 - Nov. 26, 2021

More optimism about the current weather pattern -- several snow chances for most of Colorado's high country.

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Updated Fri Nov 19, 2021 1:30pm MST | Published Fri Nov 19, 2021

By Thomas Horner

7-Day Snow Planner

Northern Mountains

Park Range and N Front Range: Steamboat, Buffalo Pass, Rabbit Ears Pass, Bluebird, RMNP, IPW, Cameron Pass

6am New Snow

0-6"

Sat

1-10"

Sun

0"

Mon

0"

Tue

T-3"

Wed

1-8"

Thu

0-2"

Fri

6am Powder Potential

20%

Sat

30%

Sun

0%

Mon

0%

Tue

1%

Wed

30%

Thu

0%

Fri

I-70 Corridor

Front Range, Gore Range, etc.: Winter Park, Berthoud Pass, Jones Pass, Loveland, A-Basin, Keystone, Breck, Copper, Vail Pass, Vail, Beaver Creek

6am New Snow

0-3"

Sat

1-5"

Sun

0"

Mon

0"

Tue

T-3"

Wed

1-8"

Thu

0-2"

Fri

6am Powder Potential

5%

Sat

20%

Sun

0%

Mon

0%

Tue

1%

Wed

20%

Thu

0%

Fri

Central Mountains

Elk Mountains, Sawatch Range, Grand Mesa, West Elks: Aspen Resorts, Crested Butte, Powderhorn, Sunlight, Kebler Pass, Independence Pass, Cottonwood Pass, Monarch

6am New Snow

0-1"

Sat

T-5"

Sun

0"

Mon

0"

Tue

1-5"

Wed

1-7"

Thu

0-3"

Fri

6am Powder Potential

0%

Sat

10%

Sun

0%

Mon

0%

Tue

10%

Wed

30%

Thu

5%

Fri

Southern Mountains

San Juans: Telluride, Red Mountain Pass, Silverton, Coal Bank Pass, Purgatory, Wolf Creek

6am New Snow

0"

Sat

0-2"

Sun

0"

Mon

0-T

Tue

1-6"

Wed

1-6"

Thu

0-4"

Fri

6am Powder Potential

0%

Sat

0%

Sun

0%

Mon

0%

Tue

15%

Wed

20%

Thu

10%

Fri

Summary

  • Storm tonight through Sunday morning, favoring northern Colorado (6”+ at higher elevations in the Park Range and along the Divide).
  • Lesser totals in central Colorado, minimal accumulations in southern Colorado.
  • The I-25 corridor could see some rain showers tomorrow, but likely no snow.
  • Warmer Monday/Tuesday.
  • Storm Wednesday to Thursday – lots of uncertainty, but favoring southern and western Colorado. Could be a decent event.
  • Potential for weak to decent activity next Friday to Saturday.

Retrospective

From Tuesday to Wednesday, a weak storm impacted northern Colorado. This kicked a cold front down the Front Range.

Per Josh Larson (@coloradowx), Denver international Aiport was reporting a high temperature of 34°F at 12pm on Wednesday, compared to 70° on Tuesday. This was a plunge of 36°. The high temperature of 37° was the coldest high temperature since April 21.

(via WeatherBell)
(via WeatherBell)

In the leadup to the storm, we were most interested in whether Denver would manage to pick up measurable snowfall, with guidance hovering around a 30-40% chance. The best hope was for banded snowfall beneath a jet streak as the storm exited on Wednesday morning. Banded snowfall did setup as expected, bringing a dusting to parts of the metro area, but nothing measurable to the airport.

  • Fort Collins: 0.9”
  • Greeley: 0.5”
  • Boulder: 0.5”
  • DEN: Trace

Thus, it looks like Denver is on its way to break its record latest first date of measurable snowfall (Nov. 21, 1934). It was VERY close, if the SNODAS model is to be believed:

The Euro weather model was the clear winner for this storm, with the most consistent and accurate forecast up to the storm. This is a nice change from the past few storms in which the GFS and Canadian models performed better.

In total, a few inches of snow fell across northern Colorado, with almost no snow much south of I-70. A few resorts reported totals in the 2-4” range, but generally, totals were in the 1-2” range which is what we expected. SNODAS provides a fairly conservative overview of estimated totals:

We are going to need some more consistent snowfall to avoid a significant snowpack deficit as we approach December. Despite the few inches in northern Colorado, some resorts have delayed their opening dates, and the mountains of southern Colorado are losing more snow than they are gaining, with areas like Wolf Creek struggling to stay open.

(via NRCS)
(via NRCS)

Luckily, it looks like the next week of unsettled weather should be a bit more potent than we were thinking in our previous forecast. Still – it may not help us recover a lot of lost ground.

(via WeatherBell)
(via WeatherBell)

Forecast Discussion: Storm Through Sunday

It is lightly snowing in parts of the mountains right now as a very weak shortwave traverses across the central Rockies. This brings a decent amount of moisture but limited amounts of lift, so snow will mostly be light today until later tonight. A stronger wave is directly behind it and the jet setup looks more favorable for snow production than what we saw in our past forecast.

(via WeatherBell)
(via WeatherBell)

Colorado is in the left exit region (upper right quadrant of the black cross drawn on the above map) of a jet max until Sunday morning, which provides some large-scale lift. Jet dynamics with the jet max moving overhead should also get some banded snowfall going by Saturday morning. Moisture becomes very limited on Saturday night.

A weak, fairly dry cold front will also make its way down the Front Range on Saturday. This puts a chance of precipitation across the I-25 corridor, especially with the jet max overhead later on Saturday and the potential for a shallow upslope. Denver could get some precipitation – but it looks to occur when temperatures are still in the 40s or high 30s. That said, we’re now looking at a 5% chance that Denver could pick up accumulating snow, which would keep the city from starting to push its record latest first snowfall date back. Seems unlikely.

In the mountains, the heaviest snowfall is in far northern Colorado (Park Range) late tonight / early Saturday morning, becoming more widespread across most of central and northern Colorado during the day on Saturday, and tapering off from north to south that evening / night. Flow is initially west-southwesterly, turning northwesterly by Saturday afternoon. Light snow could linger over the high terrain into Sunday morning.

With the slightly better dynamics aloft, this actually looks to be a decent event for parts of northern Colorado. The Blend suggests that final totals in northern Colorado could be in the double digits in a few areas, particularly the higher elevations of the Park Range and along the Divide.

However, snow totals at the resorts look to be more middling (you’ll note Steamboat’s 4” vs. 12.7” at Buffalo Pass – wind direction and temperatures are far less favorable). The low end of expectations looks to be pretty brutal, maybe only an inch or two. Given the wind direction and overall dynamics, we wouldn’t be too surprised to see a few Summit County resorts report only a couple inches of new snow, if they miss out on the jet-induced banded snowfall.

We would say conditions overall are not primed for a widespread powder day, but the setup also lends itself to some big surprises at a few areas. Keep your eyes on those snow stakes.

Forecast Discussion: Storm Wednesday to Thursday

Another ridge builds across the western United States on Monday. Colorado will see above average temperatures from Monday to Tuesday.

(via WeatherBell)
(via WeatherBell)

The next storm impacts western Colorado late Tuesday / early Wednesday. Though models had once toyed with the idea of this system impacting us as closed low tracking across the Four Corners (or even further south), they are now coming into agreement that this will be more of an open wave. The operational GFS model does still think this will be a stronger, closed low, but its ensemble has started to lean away from that solution.

(via WeatherBell)
(via WeatherBell)

Regardless of general agreement, the details still look quite tricky – on the operational Euro model, the trough axis tries to cross over Colorado on Wednesday evening, but retrogrades a bit and thus remains in place over the region as stronger jet dynamics build behind it. Thus we would say the uncertainty over this storm is still very high.

Perhaps the biggest issue is a lack of moisture in northern Colorado – this event looks to mainly impact the southern mountains, and this storm will predominantly feature southwest flow.

(via WeatherBell)
(via WeatherBell)

The GFS almost entirely disagrees with the Euro’s take on the situation, with plenty of subtropical moisture advecting into the entire state on Tuesday and thus priming conditions for a decent snowfall event across the high country, including northern Colorado. This is a bit of an outlier, however, and again, its ensemble has a less chartable view.

For now, we’ll take the Euro solution and expect a much stronger event in the San Juans than in northern Colorado, though our Weekly Snow Planner still accounts for the remaining uncertainty. Regardless of what ends up happening, the San Juans and Elk Mountains (Crested Butte, Aspen) should pick up a decent amount of precip from this storm.

But actual snow totals? It appears that with the subtropical moisture, southern Colorado will struggle to hit more productive snow-liquid ratios. The Blend doesn’t have Red Mountain Pass hitting 10:1 ratios until Wednesday night, when half of the liquid precipitation has already fallen. This is perhaps a bit cynical but not entirely unreasonable. Thus final totals may be a little lower than one may expect:

Could this go big though? Definitely. This map shows a small chance of that, but with the trend in the models we expect this percentage to come up a decent amount in southern Colorado as they reach more agreement. Another limiting factor though may be a lack of decent support from the jet, with the jet max well upstream of us for most of the storm.

This is something we’d love to keep an eye on and provide updates for – but Thomas will be in the desert until Tuesday. Just know – lots of uncertainty still, and shaping up for some powder in western Colorado and the San Juans on Wednesday and Thursday morning – but northern Colorado and Summit County may only sneak a few inches out. Until models can more definitively agree on the structure of the approaching system, speculation still rules.

Forecast Discussion: Unsettled Friday to Saturday

We’re looking at a potential series of weak shortwaves on Friday and Saturday. These would mainly provide northwest flow. It’s hard to say if these will end up missing us to the north (very likely), or deepen a bit (like tomorrow’s storm) and actually be halfway decent. Northern Colorado will pick up a few inches, regardless, but more than that? We’ll see.

We’ll talk to you on Tuesday – enjoy the snow this weekend.

--

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