Colorado Weather Forecast #140: Nov. 5 - Nov. 13, 2021

A warm, dry weekend before another unsettled week. It appears unlikely that the mountains will get much snow despite several days of cold temperatures and clouds. Denver will probably not get any accumulating snow. Pattern looks warm and dry again by the following weekend.

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Updated Thu Nov 4, 2021 9:30pm MST | Published Thu Nov 4, 2021

By Thomas Horner

Summary

  • Warm and dry until Monday.
  • Weak wave Monday to Tuesday, light snow in the mountains.
  • Stronger wave Wednesday to Friday. Details still unknown, but northwest flow favors the northern and central mountains.
  • High uncertainty in the models. Most solutions are not calling for a large amount of snow into Friday despite cold temperatures and cloudiness.
  • Denver unlikely to see snow next week, though temperatures will cool significantly into Friday.
  • Another warm and dry pattern likely that subsequent weekend and the following week.

Retrospective

The past few days of snow were a decent refresher for the central and northern mountains, though overall it wasn’t as potent as we were hoping for. The net impact on Colorado’s snowpack has been an increase of 0.2” of snow-water equivalent – a couple inches of snow.

(via USDA/NRCS)
(via USDA/NRCS)

Of course, the general regime of northwest flow with the previous pattern favored some parts of Colorado over others. The average snow-water equivalent increase for snow sensors in the northern mountains was 0.5” – around half a foot of snow.

Overall, this has not been a favorable series of storms for southern Colorado – particularly the south/east San Juans and Sangres. These mountain ranges have less snow than average at this point in the season.

(via USDA/NRCS)
(via USDA/NRCS)

We did forecast some snow totals for the last stronger wave of the previous system: Nov. 2 6am to Nov. 3 6am. This wave brought a decent amount of precipitation, but warm temperatures limited how much snow actually stacked up.

The biggest forecast issue was the overproduction of snow in central Colorado, particularly the Elk Range. Weather models and ensembles were consistent in only middling snow production for this region, so the forecast bust was surprising. Q-Vector analysis shows that this area experienced the most consistently favorable dynamics:

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

The other main forecast bust was the east side of Summit County – Loveland, A-Basin, and their nearby mountain passes struggled to make it into our forecast range. Temperatures were one of the primary issues. Many of these sites picked up sufficient liquid water, but the density of snow and rate of melting/compaction robbed them of higher snow depth totals.

Forecast Verification

Here’s how we did.

Park Range

❌ Overall: Bust low.

  • ✔️ Buffalo Pass: 6-12”. Actual: 7”.
  • ✔️ Steamboat: 2-6”. Actual: 5”
  • ❌ Rabbit Ears Pass: 3-7”. Actual: 1” (Rabbit Ears Pass)
  • ✔️ Steamboat Springs: 0-2”. Actual: 0”

Front Range

❌ Overall: Bust low.

  • ✔️ Cameron Pass: 5-10”. Actual: 7”.
  • ✔️ Hidden Valley: 1-4”. Actual: Unknown. 3” estimated.
  • ✔️ Highest peaks of the Medicine Bow Mountains, RMNP, and IPW: 6-12”. Actual: 6-9”.
  • 💥 Eldora: 0-3”. Actual: 4”.
  • ✔️ Winter Park: 3-7”. Actual: 6”.
  • ✔️ East Portal and St. Mary’s Glacier: 2-6”. Actual: Unknown. 4-6” estimated.
  • ✔️ Berthoud Pass: 4-8”. Actual: 5”.
  • ❌ Jones Pass: 5-10”. Actual: 4”.
  • ✔️ Loveland: 4-8”. Actual: 4”.
  • ❌ A-Basin: 4-8”. Actual: 3”.
  • ❌ Keystone: 3-7”. Actual: 2”.
  • ✔️ Denver: 0”. Actual: 0”.
  • ✔️ Ft. Collins: 0-1”. Actual: 0”.
  • ✔️ Boulder: 0-1”. Actual: 0”.
  • ✔️ Castle Rock: 0-1”. Actual: 0”.
  • ✔️ Colorado Springs: 0-1”. Actual: 0”.

Gore, Tenmile, and north Sawatch

✔️ Overall: Forecast was too optimistic, but verified.

  • ✔️ Breck: 3-7”. Actual: 4”.
  • ✔️ Copper: 4-8”. Actual: 5”.
  • ✔️ Vail Pass: 4-8”. Actual: Unknown. 4-5” estimated.
  • ✔️ Vail: 4-8”. Actual: 6-7”.
  • ✔️ Beaver Creek: 4-8”. Actual: 4”.
  • ✔️ Ski Cooper: 1-5”: Actual: Unknown. 2” estimated.

Elk Range

💥 Overall: Bust high.

  • 💥 Aspen Mountain: 2-6”. Actual: 7”.
  • 💥 Aspen Highlands: 2-6”. Actual: 8”.
  • ✔️ Buttermilk: 1-5”: Actual: 3”.
  • 💥 Aspen Snowmass: 3-7”. Actual: 8”.
  • 💥 Crested Butte: 0-4”. Actual: 6”.
  • ✔️ Kebler Pass: 3-7”. Actual: Unknown. 3-4” estimated.
  • ✔️ Indy Pass: 3-7”. Actual: Unknown. 3-4” estimated.

Sawatch

✔️ Overall: Verified.

  • ✔️ Cottonwood Pass: 1-5”. Actual: Unknown. 3-4” estimated.
  • ✔️ Monarch: 2-6”. Actual: 3”.

San Juans

✔️ Overall: Verified.

  • ✔️ Telluride SA: T-4”. Actual: 2”.
  • ✔️ Red Mountain Pass: 1-5”. Actual: 3”.
  • ✔️ Silverton: 1-5”. Actual: Unknown. 1” estimated.
  • ✔️ Purgatory: 0-3”. Actual: Unknown. 0” estimated.
  • ✔️ Wolf Creek: 0-3”. Actual: 1”.

Other

✔️ Overall: Verified.

  • ✔️ Powderhorn: 0-4”. Actual: Unknown. Trace estimated.
  • ✔️ Sunlight: 0-3”. Actual: Unknown. 4” estimated.
  • ✔️ Cuchara: 0-2”. Actual: Unknown. T-1” estimated.
  • ✔️ Taos: 0-2”. Actual: 0”.
  • ✔️ Snowy Range: 0-4”. Actual: Unknown. 1-2” estimated.

Like the previous system, the largest disappointment for us was the inaccuracy of the Euro weather model, which is what we primarily rely on for guidance. The GFS model has been performing better at the 3-5 day range this season. This is worth noting, but still doesn’t change the fact that the Euro consistently performs better, even with the upgrades to the GFS last season.

The urban corridor did not see any snow, and we are left to wonder if Denver is flirting with its latest first date of snow on record, which is November 21st. Certainly still a few weeks before then, but we’re not seeing any serious snow signal in the models for a while.

Forecast Discussion: Warm and Dry Through Early Next Week

A ridge of high pressure is building over our region, and doesn’t look to break down until Monday.

(via WeatherBell)
(via WeatherBell)

The warmest temperatures are progged for Saturday and Sunday, with highs in the mid 70s possible for Denver and temperatures well above freezing for the mountains, at least below 13,000ft.

(via Highpoint Weather)
(via Highpoint Weather)
(via Highpoint Weather)
(via Highpoint Weather)

Another fine fall weekend!

We could see some mildly gusty conditions along the Divide as a jet max encroaches on the region, but gusts should mostly stay below 30mph.

Forecast Discussion: Stormier Pattern Monday Through Friday

On Monday afternoon, a weak shortwave should pass over northern Colorado.

(via WeatherBell)
(via WeatherBell)

This is a prelude to a stronger wave that will impact Colorado primarily from late Tuesday through late Thursday.

(via WeatherBell)
(via WeatherBell)

Both of these systems will predominantly feature northwesterly to northerly flow, leaving much of southern Colorado high and dry through the week – not atypical for La Niña. The Blend’s snowfall forecast shows the typical winners from northwest flow:

…and the numbers aren’t too impressive. The reasonable upper bounds of model uncertainty are about the same, which means we should really keep our expectations in check for the upcoming week of colder temperatures and snow. Double digits are not likely outside of the Park Range.

Let’s take a look at the range of snow totals for the ski areas.

We can see that we haven’t eliminated the chance that this pattern could pan out to be quite potent, but a vast majority of solutions are pretty disappointing considering several days of colder temperatures and cloudiness.

The uncalibrated probability products are equally unenthused:

This wave will kick a cold front down the Front Range, and the cold airmass will deepen into Thursday/Friday. Friday morning looks to be cold enough for snow to fall in Denver, but will there actually be moisture available? It doesn’t appear likely. The Blend’s analysis has just a 21% chance for accumulating snow:

We’re monitoring this trend – there’s a lot of uncertainty and this wave could certainly be more amplified than it’s looking right now. A storm system in the Pacific, along with a storm system in the Atlantic, could be more powerful than advertised, which would either hasten or slow the track and evolution of the wave impacting us. We probably wont have a better idea until later in the weekend.

Long Range: Next Weekend

It looks likely that ridging will return for the weekend of the 13th and we may experience another round of mild and dry conditions. This is likely to continue into the following week.

We’ll keep you updated as the models become more certain! Enjoy your weekend.

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