Colorado Weather Forecast #139: Nov. 1 - Nov. 7, 2021

Snow continues into Wednesday, with decent accumulations likely in northern Colorado. Denver misses another chance at accumulating snow. Warming and drying trend into early next week (70s in Denver this weekend?), then another storm.

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Updated Mon Nov 1, 2021 5:00pm MST | Published Mon Nov 1, 2021

By Thomas Horner

Summary

  • Ongoing banded snow for northern Colorado this evening.
  • Next wave of snow from Tuesday AM to Wednesday AM.
  • Decent snow totals are likely in the northern mountains, with middling totals in the central mountains, and only a little bit of snow in the southern mountains.
  • No accumulating snow expected in Denver, though some rain is expected on Tuesday.
  • Lingering snow in parts of the northern mountains into Wednesday PM.
  • Warming and drying trend into early next week – temperatures in the 70s are possible for the Front Range by the weekend, with temperatures above freezing in the high country.
  • Next storm system in the November 9-10 timeframe.

Current Conditions

Isolated bands of heavy snowfall are working their way across parts of the Divide and east/central/north Colorado. Some of these bands have embedded lightning – look for the flashes of green squares in this animation:

(via NOAA)
(via NOAA)

A jet maximum is currently located over northeast Colorado, which is responsible for the heavy banding and instability.

(via WeatherBell)
(via WeatherBell)

Some areas in the Front Range benefited from shallow upslope flow along with a few consistent bands of heavier snow. Eldora’s snow stake was showing 5” this morning, and other snow stakes in the Summit County area were showing 1-3”. Much of the Denver metro area has seen some flurries over the past 24 hours but no real accumulations

Colorado’s northern border and southern Wyoming have been more directly beneath the jet max. This has resulted in more widespread, stronger bands of snow.

Here’s a map of estimated snow over the past two days:

(Estimated Snow Accumulation, 10/30 12pm to 11/1 12pm MST. NOHRSC SNODAS model / Highpoint Weather)
(Estimated Snow Accumulation, 10/30 12pm to 11/1 12pm MST. NOHRSC SNODAS model / Highpoint Weather)

Saturday night’s cold front brought overcast skies, with low-hanging clouds sitting above an inversion of cold air. The higher terrain to the west sits above the inversion, providing a view over a sea of clouds and even some sunny skies.

On Sunday, Seth Linden found some skiable snow and sun:

(via Seth Linden)
(via Seth Linden)

While Thomas Horner scrambled the Flatirons in “mystical” conditions:

(via Thomas Horner)
(via Thomas Horner)

Overall, Colorado’s snowpack is about average for the season, which doesn’t really mean much considering the median (1” snow water equivalent) is less than a foot of snow (when factoring in compaction and such).

(via NRCS)
(via NRCS)

Our past few storms certainly favored western Colorado, while Denver and the Front Range have yet to see a decent upslope event. You can see that Colorado’s western ranges are above average for the season while its eastern ranges are below average:

(via NWC)
(via NWC)

Denver is still waiting for its first measurable snowfall event, which is now two weeks overdue, based on the average first snowfall date being October 18. Though fall is typically pretty dry for the Front Range, drought is returning and the area is now well into a precipitation deficit, with less rain and snow than usual over the past few months – and really, no serious or consistent precipitation since the start of July.

(via NWS)
(via NWS)

Forecast Discussion: Snow Chances into Wednesday

As we discussed in our previous forecast, our weather pattern for the next few days features unsettled weather and periods of snow in the mountains. After Wednesday, we return to a drier and MUCH warmer pattern for the foreseeable future.

The good news is that despite the lack of stronger upper-level dynamics (only a weak shortwave on Tuesday), there looks to be plenty of moisture to work with and just enough forcing to allow for a decent forecast for many mountain ranges in Colorado!

Let’s get the bad news out of the way first.

Snow in Denver?

Denver’s snow chances have looked to slip away yet again, though this shouldn’t come as a surprise when considering the pessimism in our previous forecast discussion. If you’re in the metro area and saw flurries today – congrats. That was probably all you’re going to get for awhile.

The HRRR weather model does have a few weak, isolated, small bands of snow wandering over the metro area into tonight, but likely not enough to accumulate on the ground. Another round of precipitation moves through on Tuesday evening, but temperatures will likely be too warm (upper 40s to lower 40s) to allow for snow.

The story will be a little different up in Ft. Collins and on the Palmer Divide (Castle Rock etc.) – up to an inch or two of snow is possible by the end of Tuesday, though the likeliest scenario is just a dusting for a few areas east of the foothills.

Decent Snow in the Mountains

The uptick in precipitation is due to a weak shortwave, which will cross over Colorado on Tuesday.

(via WeatherBell)
(via WeatherBell)

It doesn’t look like much, but it allows Colorado to spend a decent amount of time either in the right entrance region of the jet max to our east (Tuesday morning), or the left exit region of the jet to our west (Tuesday night). These dynamics are coupled with a band of moisture that should remain in place over our region for most of the event. This is a recipe for many hours of decent snowfall – perhaps not heavy (due to the lack of particularly strong dynamical forcing), but consistent!

Southwesterly flow on Tuesday morning will switch to increasingly moist westerly flow by Tuesday afternoon, with northwesterly flow by Tuesday evening. Widespread snow should wrap up in the early morning hours on Wednesday, but pockets of light orographic snow will continue into Wednesday afternoon, mostly in parts of the northern mountains.

Mountains and ski areas that are favored by northwesterly flow should get a decent amount of snow out of this event – despite snowfall rates likely not being particularly heavy. Slow and steady wins the race, sometimes. The Blend’s deterministic snow product looks pretty decent to us – highest totals are forecasted to be in the Park Range, parts of the Front Range, and Gore Range.

Models consistently show the Jones Pass, Cameron Pass, and Buffalo Pass areas as candidates for some of the higher (accessible) snow totals by Wednesday evening.

We think that areas near Vail could do a bit better than this model is showing, but warmer temperatures could be a slight limiting factor. Additionally, the northerly component of winds aloft looks to be pretty dominant towards the latter half of the event, which would limit totals for areas such as Vail that need more westerly flow.

Totals start to really drop off as we look further south in the state, where temperatures are warmer, dynamics are weaker, and moisture is less available.

The 50th percentile snow product introduces a word of caution, as its snow expectations are surprisingly low. This suggests that a large amount of uncertainty still remains in regards to the track, strength, and speed of the shortwave impacting us.

However, the calibrated probabilistic precipitation products, which take into account how well models have been performing with similar setups, look a lot better.

Considering a decent amount of agreement in the deterministic models and high resolution models for a more impactful event, we would probably consider the above 50th percentile map (after applying a 10:1 snow-liquid ratio) to be the lower bounds of potential snowfall from Tuesday AM to Wednesday AM.

6am Tuesday to 6am Wednesday Snow Forecast

Here’s our snow forecast for 6am Tuesday to 6am Wednesday. Keep in mind that the northern ranges could pick up a few more inches of snow into Wednesday afternoon too, in addition to a few inches before this event due to the ongoing bands of snow this evening. We think these ranges are a little conservative and the size of the range indicates the remaining level of uncertainty (both amount of precipitation and temperatures/snow-liquid ratio).

Park Range

  • Buffalo Pass: 6-12”
  • Steamboat: 2-6” (temperatures will be a big problem)
  • Rabbit Ears Pass: 3-7”
  • Steamboat Springs: 0-2” (maybe all rain)

Front Range

  • Cameron Pass: 5-10”
  • Hidden Valley: 1-4”
  • Highest peaks of the Medicine Bow Mountains, RMNP, and IPW: 6-12”
  • Eldora: 0-3”
  • Winter Park: 3-7”
  • East Portal and St. Mary’s Glacier: 2-6”
  • Berthoud Pass: 4-8”
  • Jones Pass: 5-10”
  • Loveland: 4-8”
  • A-Basin: 4-8” (Loveland should get higher totals, though)
  • Keystone: 3-7”
  • Denver: 0”
  • Ft. Collins: 0-1”
  • Boulder: 0-1”
  • Castle Rock: 0-1”
  • Colorado Springs: 0-1”

Gore, Tenmile, and north Sawatch

  • Breck: 3-7”
  • Copper: 4-8”
  • Vail Pass: 4-8”
  • Vail: 4-8”
  • Beaver Creek: 4-8”
  • Ski Cooper: 1-5”

Elk Range

  • Aspen Mountain: 2-6”
  • Aspen Highlands: 2-6”
  • Buttermilk: 1-5”
  • Aspen Snowmass: 3-7”
  • Crested Butte: 0-4”
  • Kebler Pass: 3-7”
  • Indy Pass: 3-7”

Sawatch

  • Cottonwood Pass: 1-5”
  • Monarch: 2-6”

San Juans

  • Telluride SA: T-4”
  • Red Mountain Pass: 1-5”
  • Silverton: 1-5”
  • Purgatory: 0-3”
  • Wolf Creek: 0-3”

Other

  • Powderhorn: 0-4”
  • Sunlight: 0-3”
  • Cuchara: 0-2”
  • Taos: 0-2”
  • Snowy Range: 0-4”

Warming Into Next Week

Warmer, drier air starts to advect into Colorado on Thursday as ridging strengthens over the western United States. This trend continues into the weekend, with the warmest air coming ahead of our next potential storm next week (likely Tuesday or Wednesday).

(via WeatherBell)
(via WeatherBell)

Another glorious weekend is on tap.

Keen observers will also notice the end of Daylight Savings Time.
Keen observers will also notice the end of Daylight Savings Time.

Due to uncertainty in the weather models, the above high temperatures may actually be a bit conservative. The deterministic Euro model’s expectations are for temperatures well into the 70s for the Denver metro area.

(via WeatherBell)
(via WeatherBell)

This is just a few degrees shy of early November temperature records, which top out at around 78-79 degrees for Denver.

The warmth will likely do quite a number on our shallow early season snowpack, even at altitude.

(via WeatherBell)
(via WeatherBell)

The Euro model expects 3-7” of snow to melt from Thursday to Tuesday.

Late Thursday to early Friday looks to feature some very strong gusts along the Divide as a front pushes through northern and central Colorado. There could be some gusty conditions on the plains on Friday morning associated with this.

Next Storm: Tuesday or Wednesday Next Week

Ensembles are showing a pretty decent signal for a storm on Tuesday or Wednesday of next week. This looks to be another northwesterly flow event. There is too much uncertainty to discuss details, but this has the potential to be a decent storm – Berthoud Pass has a 10% chance of picking up more than a foot of snow from this system, and Denver has a 25% chance of picking up some measurable snow. We’ll have to wait and see.

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