This is the most creative read-submitted photo to date. I love it!

It appears that this pumpkin carving will, in fact, bring the snow, because we should see flakes during two days this week, and again during the upcoming weekend or early the following week.

Monday snow (Storm 12)

A fast-moving system will slide from north-to-south across eastern Colorado on Monday morning. The foothills and plains east of the divide should wake up to flakes on Monday morning, and the best chance for 1-3 inches of snow will be in the foothills east of the divide, focused on Rocky Mountain National Park, Indian Peaks, Eldora, and Echo.

Some snow from this storm could push toward and west of the divide. If you like to start your week off with turns instead of work (who doesn't?!), Loveland and Abasin could get a fresh coating.

Tuesday snow (Storm 13)

The more significant system this week will arrive on Monday evening and bring snow through Tuesday evening.

As we have been talking about for a few days, this storm could produce significant snow (5-10 inches) over a small-ish area of Colorado. When I use the word 'small' I do so in atmospheric terms, where an area 50-75 miles wide is a blip on the scale of the earth. Because this storm will only focus the heaviest snow over a small area, the forecast is trickier than normal. If the storm shifts just a few miles north or south, then one mountain will get more snow and another nearby area could get much less.

For the past two days, most models have been in agreement that the heaviest snow will fall south of I-70 and north of the New Mexico border.

And, at this point, most models still agree with this scenario, so confidence is increasing somewhat that the central and southern mountains will see the heaviest snow.

Here are some maps.

First, the American GFS model shows the heaviest snow, roughly 4-10 inches, from Aspen extending south to Crested Butte, Monarch, Telluride, Silverton, Purgatory, and Wolf Creek.

Second, here is the European (ECMWF) model. Usually, I cannot show the precipitation forecast from this model, but a team at http://wx.graphics and http://www.weather.us is creating free-to-use maps with wider rights for republication, so I hope to be able to include more of these maps in the future.

The ECMWF model above shows total precipitation, so multiply by about 10 to estimate snowfall. Once again, the deepest totals are forecast from Aspen south to the central and southern mountains.

Of course, long-term readers know that the most responsible way to make a forecast is to not look at just one or two models but to look an 'ensemble' of models. The European model runs 51 versions of its model with slightly different data and produces a range of forecasts. Here is the average forecast of the 51 versions of the European model.

Mountains ordered from north-to-south:

Copper Mountain - 4"

Aspen - 5-6"

Crested Butte - 7-8"

Monarch - 6-7"

Telluride - 5"

Silverton - 6-7"

Purgatory - 6-7"

Wolf Creek - 4"

The average of the 51 versions of the European model can somewhat under-estimate snowfall because the model is not at a high enough resolution to accurately model the mountainous terrain. But, despite this shortcoming, I like to look at the average of the 51 versions as it is usually one of the more accurate methods of forecasting precipitation.

There are reasons why snowfall could be more than this forecast. The storm could shift just a bit north, which would bring less snow to the southern mountains and more to the I-70 mountains. The storm could shift just a bit south, which would bring more snow to the southern mountains. And, importantly, any narrow bands of super intense snow could drop 1-2 inches per hour and increase snow totals.

There are reasons why snowfall could lower than this forecast. The storm is tricky, relying on a few weak ingredients to create the snow, and if any of these ingredients shift just a bit, the storm will not produce as much snow. Also, temperatures will be rather warm, and the snow level will likely be around 8,000-9,000 feet, which might keep the snow on the thicker side.

Recap: expect about 4-8+ inches of snow in the central and southern mountains from Monday night through Tuesday afternoon.

The Halloween system will be a fun storm to watch ... I'll write another short post on Monday afternoon/evening with an update as the storm gets rolling.

Following the snow on Tuesday, it appears that we should see dry weather on Wednesday, Thursday, Friday, and Saturday. The only significant weather during this time could be windy conditions over the ridges and peaks.

Next weekend, a powerful storm will bring snow to the West Coast, including a few feet of snow likely in California.

This west-coast storm will move east, toward Colorado, and could bring snow sometime between Sunday, November 5 and Tuesday, November 7.

I fear that the brunt of the storm will track north of Colorado (see red arrow above). This northern track could still bring snow to Colorado, but not as much as if it tracked directly over our state. I'll keep you posted!

Thanks for reading!

JOEL GRATZ

Colorado Forecast Page: https://opensnow.com/state/co

Next Talks

Bentgate Mountaineering in Golden on Wednesday, November 8th. See you there!
https://www.facebook.com/events/1209665705844183/

Mountain Chalet in Colorado Springs on Wednesday, November 15th. See you there!
I'll post more details soon

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, Abasin, 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