From the Air

I love that so many readers are looking out the window while they are flying over Colorado and that folks are sending me the pictures so that I can post them for all of us to enjoy.

This is the calm before the storm with images of our mountains from this weekend.

Snow Monday Night, Powder on Tuesday

Monday will be dry for most of the day for most of the state.

Then the storm will track directly over Colorado from Monday night through Tuesday midday, and this storm will strengthen as it traverses the state from west-to-east.

I like strengthening storms as they usually at least meet our expectations, and often there are upside surprises.

The only downside to this system is that as it moves directly over Colorado, some of the northern mountains will see a wind direction from the east on Tuesday morning, and this will somewhat cut down on snow totals.

The only change that I’m making to the going forecast is to now include some southern mountains in the higher snow totals. The storm will drop just a bit farther south than I previously thought, and the wind direction from the west and northwest should work well for Telluride and Silverton, and a southwest wind direction during some of the storm should also work well at Wolf Creek.

I’ll stick with 5-10 inches for the northern and central mountains, and will now include Telluride, Silverton, and Wolf Creek in these amounts. Areas north of I-70 and east of the continental divide have a chance to get to 10-20 inches, and this includes Eldora, the Indian Peaks, north up to Rocky Mountain National Park, and east from the foothills out to the cities around Boulder, Ft. Collins, and maybe parts of Denver.

While snow amounts are always a little uncertain, the timing of the heaviest snow on Monday night and Tuesday morning is pretty much a lock, so it’s easy to say that Tuesday will be the best powder day for this system. Expect freshies for first chair and more snow falling through about Tuesday at noon.

Each day I look through tens of snow forecasts produced by different models and different versions of each model. I then pick maps to post that show roughly the average snow forecast, or at least a believable snow forecast (sometimes, a few models look like they are out to lunch).

Below is the precipitation forecast map from the German ICON model. It looks pretty reasonable to me and is roughly the average of many models. Remember, this is precipitation and we’ll need to convert it to snow by multiplying the numbers by roughly 15. A snow-to-liquid ratio of 15-to-1 is average for mid-winter in Colorado and represents good snow quality – light and fluffy.

You can see on the map above that most mountains will fall in the 0.3 – 0.6 inch range, or multiplied by 15  =  4.5 – 9.0 inches of snow. With a strengthening storm, I’m fine to round this up to 5-10 inches. Areas on the upper-right part of the map are around 1 inch of precipitation, which could be 15+ inches of snow.

For another perspective, let’s look at the CAIC WRF 2km model below.

Again, most mountains are in the yellow to light red color signifying 6-10 inches, and areas in the upper-right are 10-20 inches.

To wrap this up, look for snow Monday night through the first half of Tuesday with 5-10 inches for most areas and 10-20 inches north of I-70 and east of the divide. Tuesday morning should be a fun powder day with chilly but reasonable temperatures in the upper single digits to low teens. Enjoy!

Thanksgiving Week Openings

Crested Butte: November 27

Purgatory: November 27

Telluride: November 28 (Donation Day on Nov 27th)

We will see dry weather from Tuesday late afternoon through Wednesday late afternoon.

From Wednesday night through Thursday night, the next storm will bring snow to mostly the southern part of the southern mountains (Silverton, Purgatory, Wolf Creek). Amounts for these mountains could be in the 6-12 inch range.

Then from Thursday night through Saturday morning, the brunt of the storm should push across Colorado and this is when all mountains should see snow. My early estimate is that all mountains will grab an average of 4-10 inches while the southern mountains could see 10-20 additional inches.

In the south (Wolf Creek, Silverton, Purgatory), the best powder should be on Thursday and Friday with a storm total of 2+ feet.

For all other mountains, Friday could be a powder day, as could Saturday, and total snowfall should be in the 4-10 inch range.

While snow showers could continue through Saturday, we will also see very cold temperatures in the single digits above zero. Air masses with very cold temperatures usually lack moisture, which means snow accumulations are light. This is a bummer because, with somewhat warmer temperatures, we would have a better chance for more snow significant snow on Saturday thanks to moisture and energy hanging over Colorado in wrap-around flow.

To recap, powder in the south on Thursday and Friday and powder everywhere on Friday and maybe Saturday morning.

After this late-week storm and looking into the first five days of December, there will be storms around the US but right now all of them look to NOT make a direct hit on Colorado so we might be completely dry or see only a period of light snow. But I’m not that bummed because the two storms this week will help to build our base and we should see more terrain open by the weekend.

Thanks for reading!

My next update will be on Tuesday morning.

JOEL GRATZ

PS – I have two more talks on my schedule 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.

* Breckenridge: Dec 6 @ Colorado Mountain College Breckenridge
- Startup Weekend Kickoff Event
- 530 Dinner & Networking
- 630 My presentation discussing BOTH business & weather 
- 730 Startup Weekend Kickoff
- 830 Wrap up
- Tickets $25 includes dinner with a portion of proceeds donated to local non-profits
- See the event overview and buy tickets

* 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)

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