Storm Summary for Wednesday to Friday

The storm has started!

While the image below may not look that exciting to most people, it brings me (and likely you) a lot of joy when we see snow falling at night on a CDOT cam. This shot is near Hesperus, just west of Durango, at 8,200 feet.

Expect to see snow from now (Wednesday morning) through Friday.

The deepest totals of 12-20 inches will be in the southern mountains because they will see intense waves of snow AND the wind direction from the south and southwest favors these mountains.

Expect lower totals in the central and northern mountains with roughly 5-10 inches. These mountains will see multiple intense waves of snow which could each deliver 1-4 inches in a few hours. But otherwise, the wind direction will not be favorable for most of the storm, which is why my expectations are lower.

The forecast map from the CAIC WRF 2km model does a reasonable job showing the difference between the far southern mountains and the rest of the state. Around Purgatory, Silverton, and Wolf Creek, amounts are solidly over 10 inches. North of that, amounts generally just touch 10 inches at the high end.

The beginning of the storm will be warm with snow levels near and above 8,000 feet and rain possible at some lower-elevation areas. The end of the storm will be colder with snow down to valley bottoms.

Storm Details

I am going to compare the deeper forecasts for the southern mountains of Wolf Creek with the lighter forecasts for the northern mountain area of Vail Pass.

At Wolf Creek in the southern mountains, the University of Utah multi-model forecast shows a range of 13-22 inches with an average of about 18-20 inches. Below that, the CAIC WRF 2km model also shows about 20 inches. I like it when forecasts agree as it increases confidence. Notice in the lower CAIC WRF 2km forecast, the snow will fall for 24 hours or so.

At Vail Pass in the northern mountains, the story is different. First, the University of Utah multi-model forecast shows much less agreement, with a super wide range, and this lowers my confidence in the forecast. Based on an unfavorable wind direction, the American model’s forecast of 18” looks too high and has a low chance of verifying. The CAIC 2km model’s forecast of 9 inches looks more reasonable, and you can see that this amount comes from three short and intense bursts of snow.

When I see short, intense bursts of snow in the forecast, my confidence in snow totals decreases because the models do not forecast these bursts with consistent accuracy. Sometimes a heavier cell could miss a mountain and the mountain gets little snow, and other times, the burst is more impressive than the models understand and we see 2 inch-per-hour snowfall rates for a few hours.

Powder Potential

The resorts that are open this week are in the northern mountains. Based on the timing of the waves of snow, there could be a few inches of powder Wednesday afternoon, again Thursday morning or midday, and then colder and fluffier powder on Friday morning.

In the southern mountains, Purgatory and Wolf Creek are scheduled to open on Saturday, but most of the snow will fall on little to no base and should end on Thursday, so any fresh powder remaining on Saturday will be settled.

These are the mountains that announced openings this weekend.

Aspen Mountain – Opening for the season on Sat, Nov 23

Beaver Creek – Opening for the season on Sat, Nov 23

Snowmass – Opening for the season on Sat, Nov 23

Purgatory – Opening for the season on Sat, Nov 23

Wolf Creek – Opening for the weekend on Sat, Nov 23

Good news, good news, good news.

Following a dry weekend, I see a potential storm every few days during Thanksgiving week and the week after.

During Thanksgiving week, NOAA’s outlooks shows a good chance of below-average temperatures and above-average precipitation. That’s what we want to see.

If you like storms, you should enjoy the model animation from November 25 – December 5. Blue colors mean generally cooler and stormier conditions.

In my post on Thursday, I should be able to start looking at some details of the potential storms during the week of Thanksgiving.

Thanks for reading!

My next update will be on Thursday morning.

JOEL GRATZ

PS – There are still a few talks coming up and I hope to see some of you at one of them (listed below)!

Upcoming talks

These talks are usually 45 minutes and allow me to show a little of the science behind snow forecasting, have some fun, and answer lots of questions. I’ll post details about each talk as they are available.

* Evergreen: Nov 21 @ Boone Mountain Sports / Evergreen Brewery
- Doors open at 600pm, beer and great food available for purchase
- My talk starts at 700pm
- Directions and details

* Breckenridge: Dec 6 @ Colorado Mountain College Breckenridge

* Basalt: Dec 12 @ Bristlecone Mountain Sports
- 700-730 Light refreshments
- 730-830 Presentation + Q&A
- Tickets are $10/person (proceeds benefit Roaring Fork Conservancy)
- More details
- Purchase a ticket in advance (might sell out)

Plug for the 12th Annual CAIC Benefit Bash

- November 23rd at the Breckenridge Riverwalk Center
- The biggest fundraiser of the year for CAIC
- LOTS of prizes, awesome live music, silent and live auctions, dinner, and drinks
- Win skis, splitboards, packs, and more
- Get your ticket today!

Geography Key

Northern Mountains
Steamboat, Granby, Beaver Creek, Vail, Ski Cooper, Copper, Breckenridge, Keystone, Loveland, Abasin, Winter Park, Berthoud Pass, Eldora, Rocky Mountain National Park, Cameron Pass

Along the Divide
Loveland, Arapahoe Basin, Winter Park, Berthoud Pass

East of the Divide
Eldora, Echo, Rocky Mountain National Park, Cameron Pass

Central Mountains
Aspen, Sunlight, Monarch, Crested Butte, Irwin, Powderhorn

Southern Mountains
Telluride, Silverton – north side of the southern mountains | Purgatory, Wolf Creek – south side of the southern mountains