The signal that it is autumn in Colorado is when the first significant storm arrives and Silverton sends out a picture of one of their patrollers slashing a powder turn. Based on area SNOTEL measurements, it looks like the Silverton area received 10-12 inches of snow on Tuesday morning.

Below are the snowfall totals that's I've gathered from cams and SNOTEL sites. The snowfall on Tuesday was pretty dense as temperatures were somewhat warm and a lot of the snow fell from convective (thunderstorm-like) cells. The last bit of snow now early on Wednesday morning was fluffier. I'm estimating a storm average of about a 10-to-1 snow-to-liquid ratio.

Northern Mountains

12-14" Buffalo Pass north of Steamboat (based on 1.3 inches liquid)
10-12" Cameron Pass (based on 1.1 inches liquid)
10-12" Rocky Mountain National Park (based on 1.1 inches liquid)
8" Arapahoe Basin
8" Keystone (their stake reset halfway through the storm with 4" on either side of the reset)
8" Loveland
4" Breckenridge
4" Eldora
4" Winter Park
3" Beaver Creek
3" Copper
3" Vail

Central Mountains

9-11" Grand Mesa (based on 1.0 inches liquid)
1-3" Most other areas (likely more in the Elks where there are no sensors)

Southern Mountains

12-15" Wolf Creek (based on 1.1 to 1.3 inches liquid)
10-12" Red Mountain Pass (based on 1.1 inches liquid)
10" Coal Bank Pass
10" Telluride
8" Purgatory

It's only early season, but it's fun to see snowstake cams like A-Basin's (see below). Looking at the timelapse of A-Basin's cam, the first couple rounds of snow on Tuesday were thicker and denser, then the snow that fell early on Wednesday morning was lighter and fluffier as it was produced by moderate winds and orographic lift rather than intense thunderstorm-like cells.

The forecast for Tuesday's storm worked out reasonably well with the double-digit totals split between the southern mountains and the far northern mountains. The southern mountains had a beneficial wind direction during much of the storm, and the far northern mountains benefited from a good west wind direction late in the storm as well as the proximity of the storm energy late in the storm. In between the southern and far northern mountains, we relied on the random location of convection (cells putting down intense snow) to produce most of the precipitation, and some spots got the snow while others didn't.

Wednesday dry

Now on Wednesday morning, the storm is moving away.

For the rest of Wednesday, most mountains will remain mostly cloudy, and any remaining snow showers should wane during the morning (maybe another inch or two of accumulation?), and then Wednesday afternoon and evening should be dry.

Thursday & Thursday night storm

A second storm will bring snow during the day, starting mid-morning Thursday, and snow should fall throughout the day and through the night, ending by Friday morning around sunrise.

Thursday's storm will be weaker than Tuesday's system, so snow amounts will be lower, but this storm will be colder, so the snow will be a little fluffier, and the snow-to-liquid ratios will be higher.

We'll see northwest winds during much of Thursday afternoon and Thursday night, and this should favor the northern mountains, areas around Aspen and the northwestern side of the central mountains, and also the northern San Juan mountains (northern part of the southern mountains).

Total snowfall should be in the 2-5 inch range, though up to 8 inches isn't out of the question.

One fun piece of the storm is that the jet stream will nose itself overhead early on Friday morning, and when this happens on top of northwest flow and the right mountain-top temperatures of about 10°F, there can be some 'extra' snow over the northern mountains that models can underestimate. It's something to watch for on Friday morning. If only this were mid-winter, it would be a reason to watch for a fun and maybe sneaky-good powder morning on Friday.

Friday, Saturday, and Sunday

Look for dry weather all three days with temperatures warming each day. The super favorable snowmaking weather that we'll see on Thursday and Friday will gradually warm, still allowing for snowmaking, but maybe not 24/7.

Monday & Tuesday

We'll start off next week with a weak storm. We could see just some clouds and no snow, or there could be some accumulating snow. If it even happens, it doesn't look like a significant storm.

Next Wednesday to Sunday (October 20-24)

We'll switch to dry and warm weather. Maybe there will be some high-elevation snowmaking that continues at night, aided by dry air, but temperatures won't be ideal.

Storm around Monday, October 25?

The next chance for a storm will be around Monday, October 25. This is when stormy weather along the west coast should finally push east. It's far too early to know if this will be a weak system or just the first energy of what could be a stormy week. We'll see.

My next update will be on Thursday, October 14.

Thanks for reading!

JOEL GRATZ

Geography Key

Northern Mountains
Steamboat, Bluebird Backcountry, Granby, Beaver Creek, Vail, Ski Cooper, Copper, Breckenridge, Keystone, Loveland, Arapahoe Basin, 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