Colorado Weather Forecast #151: Dec. 7 - Dec. 15, 2021

Colorado's biggest, coldest storm of the season will produce decent snow from Wednesday to Friday for most areas -- except the Front Range.

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Updated Tue Dec 7, 2021 6:00pm MST | Published Tue Dec 7, 2021

By Thomas Horner

7-Day Snow Planner (Through Dec. 14)

230

Days since the last measurable snowfall in Denver (At the official weather station / 2nd longest streak since record keeping began)

93%

Chance of accumulating snow in Denver by Dec. 12th (At the official weather station)

Northern Mountains

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

6am New Snow

0-3"

Wed

1-5"

Thu

5-14"

Fri

2-5"

Sat

0"

Sun

0"

Mon

0-T

Tue

6am Powder Potential

10%

Wed

15%

Thu

75%

Fri

20%

Sat

0%

Sun

0%

Mon

0%

Tue

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-T

Wed

0-3"

Thu

2-8"

Fri

2-5"

Sat

0"

Sun

0"

Mon

0-T

Tue

6am Powder Potential

0%

Wed

5%

Thu

30%

Fri

20%

Sat

0%

Sun

0%

Mon

0%

Tue

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-T

Wed

1-5"

Thu

5-13"

Fri

2-5"

Sat

0"

Sun

0"

Mon

0-T

Tue

6am Powder Potential

0%

Wed

15%

Thu

75%

Fri

20%

Sat

0%

Sun

0%

Mon

0%

Tue

Southern Mountains

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

6am New Snow

T-1"

Wed

1-5"

Thu

8-16"

Fri

2-7"

Sat

0"

Sun

0"

Mon

0-1"

Tue

6am Powder Potential

0%

Wed

10%

Thu

90%

Fri

25%

Sat

0%

Sun

0%

Mon

0%

Tue

Denver Metro

Denver and surrounding suburbs: Lakewood, Westminster, Aurora, Highlands Ranch

6am New Snow

0"

Wed

0"

Thu

T-1"

Fri

1-3"

Sat

0"

Sun

0"

Mon

0"

Tue

6am Snow Accum. Chance

0%

Wed

0%

Thu

65%

Fri

80%

Sat

0%

Sun

0%

Mon

0%

Tue

Summary

  • Weak storm wrapping up today, but some okay totals in parts of the San Juans and at Vail/Breck/Copper.
  • Much stronger storm from Wednesday to Saturday – actually two waves. Two feet of snow is possible. Snowfall expectations are very uncertain.
  • Very cold into the weekend.

Forecast Update: Dec. 6-8 Storm

Light snow continues to fall across Colorado this morning and into the afternoon. This has brought another couple inches to a few places since reports this morning, though periods of sun and higher temperatures today have compacted what fell last night. Strong winds are also transporting snow at higher elevation. We are still expecting parts of the northern mountains (such as Buffalo Pass) to pick up a couple more inches over the course today.

(via WeatherBell)
(via WeatherBell)

How have models and forecasters done with this storm? Overall, not too bad. The downward trend in model expectations up to the storm was legitimate, and we barely scraped into our low end snow expectations for most areas, except some surprises in the high San Juans (Red Mountain Pass) and near Breck and Copper (4”).

The biggest issue for forecasters and weather models was northern Colorado, which was mostly skunked by this storm – Steamboat’s snow stake is still sitting at 1”, though the Buffalo Pass SNOTEL has picked up ~0.3” of SWE, which is probably 3-5” of snow, still below our forecast range (5-10”). Almost everyone had double digit totals for that area, with the CAIC WRF’s 10-20” forecast looking quite unattainable as this storm winds down.

Hello darkness my old friend... (via Steamboat)
Hello darkness my old friend... (via Steamboat)

For the weather models below, we did not pull in any of the Monday 12/6 12Z runs – we wanted to see who had the best predictions as of Sunday night. The 12/6 12Z model runs were a big trend down across the board, and likely would’ve resulted in better performance. We saw it coming, and our forecast verified better than anyone else, though we needed slightly larger ranges to get there.

There will still be some changes as more data comes in – it looks like Copper got another inch (which busts our forecast there), Buffalo Pass continues to get snow, Wolf Creek Pass SNOTEL picked up 2” this morning (thus the resort may report 2” tomorrow), and Red Mountain Pass and Berthoud Pass look to continue to get some snow. But overall, it’s pretty clear that the NAM outperformed the other models again (like our last storm that we used this tool for!), and human forecasters did better than the GFS and Euro. The Euro really sucked this time around, with a strong wet bias.

―――――――

Snow Forecast Comparison and Verification Chart

Last updated Wednesday December 8, 2021 12pm.

Forecast Start: Monday December 6, 2021 5am

Forecast End: Wednesday December 8, 2021 5am

* = 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.

Thomas Horner Weather Forecaster @ Highpoint Weather

Issued Sun Dec. 5 11pm
✔️ Verified
84%
33/39
Score
31%
62/195
🎯 Spread
3.2
average
💥 High
3
7%
❌ Low
3
7%

Note: (Fri Dec. 3 11pm) Going for tighter ranges this time around.

Central Colorado
13/45pts (28%) ✔️9/9 (100%) 💥0/9 (0%) ❌0/9 (0%)

Aspen Highlands: 2-5" Forecast Actual2" ✔️

1pts
2" Dec 7 5am (Official)
0" Dec 8 5am (Official)

Aspen Mountain: 2-5" Forecast Actual2" ✔️

1pts
2" Dec 7 5am (Official)
0" Dec 8 5am (Official)

Aspen Snowmass: 2-6" Forecast Actual3" ✔️

1pts
2" Dec 7 5am (Official)
1" Dec 8 5am (Official)

Buttermilk: 1-4" Forecast Actual3" ✔️

2pts
2" Dec 7 5am (Official)
1" Dec 8 5am (Official)

Cottonwood Pass*: 1-3" Forecast Actual1" ✔️

2pts
1" Dec 7 5am (Estimated)
0" Dec 8 5am (Estimated)

Crested Butte: 1-5" Forecast Actual2" ✔️

1pts
2" Dec 7 5am (Official)
0" Dec 8 5am (Official)

Independence Pass*: 1-4" Forecast Actual2" ✔️

2pts
2" Dec 7 5am (Estimated)
0" Dec 8 5am (Estimated)

Kebler Pass*: 3-7" Forecast Actual4" ✔️

2pts
3" Dec 7 5am (Estimated)
1" Dec 8 5am (Estimated)

Monarch: 2-6" Forecast Actual2" ✔️

1pts
2" Dec 7 5am (Official)
0" Dec 8 5am (Official)

Front Range
11/25pts (44%) ✔️5/5 (100%) 💥0/5 (0%) ❌0/5 (0%)

Cameron Pass: 1-5" Forecast Actual3" ✔️

1pts
2" Dec 9am (SNODAS)
1" Dec 8 5am (SNODAS)

East Portal*: 0-3" Forecast Actual1" ✔️

2pts
0" Dec 7 5am (Estimated)
1" Dec 8 5am (Estimated)

Eldora: 0-2" Forecast Actual0" ✔️

3pts
0" Dec 7 5am (Official)
0" Dec 8 5am (Official)

Hidden Valley*: 0-3" Forecast Actual2" ✔️

2pts
1" Dec 7 5am (Estimated)
1" Dec 8 5am (Official)

St. Mary's Glacier*: 0-2" Forecast Actual1" ✔️

3pts
0" Dec 7 5am (Estimated)
1" Dec 8 5am (Official)

I-70 East
12/35pts (34%) ✔️7/7 (100%) 💥0/7 (0%) ❌0/7 (0%)

A-Basin: 1-4" Forecast Actual1" ✔️

2pts
1" Dec 7 5am (Official)
0" Dec 8 5am (Official)

Berthoud Pass: 1-5" Forecast Actual2" ✔️

1pts
2" Dec 7 9am (SNODAS)
0" Dec 8 5am (SNODAS)

Echo Mountain*: 0-1" Forecast Actual1" ✔️

4pts
0" Dec 7 5am (Estimated)
1" Dec 8 5am (Estimated)

Jones Pass: 1-5" Forecast Actual1" ✔️

1pts
1" Dec 7 8am (SNOTEL)
0" Dec 8 5am (SNOTEL)

Keystone: 1-3" Forecast Actual1" ✔️

2pts
1" Dec 7 5am (Official)
0" Dec 8 5am (Official)

Loveland S.A.: 1-5" Forecast Actual1" ✔️

1pts
1" Dec 7 5am (Official)
0" Dec 8 5am (Official)

Winter Park: 1-5" Forecast Actual2" ✔️

1pts
2" Dec 7 5am (Official)
0" Dec 8 5am (Official)

I-70 West
11/35pts (31%) ✔️7/7 (100%) 💥0/7 (0%) ❌0/7 (0%)

Beaver Creek: 2-6" Forecast Actual2" ✔️

1pts
2" Dec 7 5am (Official)
0" Dec 8 5am (Official)

Breckenridge S.A.: 1-4" Forecast Actual4" ✔️

2pts
4" Dec 7 5am (Official)
0" Dec 8 5am (Official)

Copper Mountain: 1-4" Forecast Actual4" ✔️

2pts
4" Dec 7 5am (Official)
0" Dec 8 5am (Official)

Powderhorn: 1-4" Forecast Actual2" ✔️

2pts
2" Dec 7 5am (Official)
0" Dec 8 5am (Official)

Ski Cooper*: 1-4" Forecast Actual2" ✔️

2pts
2" Dec 7 5am (Estimated)
0" Dec 8 5am (Estimated)

Sunlight*: 2-5" Forecast Actual2" ✔️

1pts
2" Dec 7 5am (Estimated)
0" Dec 8 5am (Estimated)

Vail Pass*: 1-5" Forecast Actual N/A

Vail S.A.: 2-6" Forecast Actual4" ✔️

1pts
4" Dec 7 5am (Official)
0" Dec 8 5am (Official)

Park Range / WY
0/20pts (0%) ✔️0/4 (0%) 💥1/4 (25%) ❌3/4 (75%)

Bluebird*: 2-6" Forecast Actual N/A

Buffalo Pass: 5-10" Forecast Actual3" ❌️

2" Dec 7 5am (SNOTEL)
1" Dec 8 5am (SNOTEL)
Note: SNOTEL recorded 0.5" of SWE change -- maybe 6"+ of snow fell, but wind may have stripped it from the station's depth gauge.

Rabbit Ears Pass: 3-7" Forecast Actual1" ❌️

1" Dec 7 5am (SNOTEL)
0" Dec 8 5am (SNOTEL)

Snowy Range*: 1-5" Forecast Actual7" 💥️

6" Dec 7 5am (Estimated)
1" Dec 8 5am (Estimated)

Steamboat S.A.: 3-7" Forecast Actual2" ❌️

1" Dec 7 5am (Official)
1" Dec 8 5am (Official)

Southern Colorado / NM
15/35pts (42%) ✔️5/7 (71%) 💥2/7 (28%) ❌0/7 (0%)

Cuchara*: 0" Forecast Actual0" ✔️

5pts
0" Dec 7 5am (Estimated)
0" Dec 8 5am (Estimated)

Purgatory: 1-4" Forecast Actual5" 💥️

3" Dec 7 5am (Official)
2" Dec 8 5am (Official)

Red Mountain Pass: 3-7" Forecast Actual9" 💥️

8" Dec 7 9am (SNOTEL)
1" Dec 8 5am (SNOTEL)

Silverton S.A.*: 3-7" Forecast Actual7" ✔️

2pts
6" Dec 8 5am (Estimated)
1" Dec 8 5am (Estimated)

Taos S.A.: 0-1" Forecast Actual0" ✔️

4pts
0" Dec 7 5am (Official)
0" Dec 8 5am (Official)

Telluride S.A.: 3-7" Forecast Actual6" ✔️

2pts
6" Dec 7 5am (Official)
0" Dec 8 5am (Official)

Wolf Creek: 0-3" Forecast Actual2" ✔️

2pts
0" Dec 7 5am (Official)
2" Dec 8 5am (Official)