Saturday and Sunday (September 25-26) were beautiful fall days across most of Colorado. The atmosphere mixed things up a bit with afternoon showers over the southern mountains on Sunday, but otherwise, there were lots of blue skies and golden Aspen leaves to enjoy.

Monday will be a mixed day with dry weather over the northern mountains and showers over the central and southern mountains. A storm is swirling over New Mexico and Arizona and the proximity of the storm is why the southern mountains will have the highest chance for showers. Most of these showers should fall in the form of rain, though the highest peaks could see snowflakes. The animation below is the satellite + radar just before sunrise on Monday morning, and the swirl of the storm is evident over New Mexico and Arizona.

Tuesday and Wednesday will be active weather days with showers, thunderstorms, and some snowfall. One round of rain and snow will move through on Tuesday, with another round of showers likely between Wednesday morning and late Wednesday night.

On Tuesday and Wednesday, there will be plenty of moisture in the air, and therefore there will be a chance for plenty of precipitation, maybe on average 0.5 inches or so. Let's hope that the areas of more intense precipitation just miss the wildfire burn scars as we do not need to deal with any additional debris flows. 

In terms of snowfall, yes, there will be some, at the higher elevations. The multi-model ensemble forecasts show a high chance (near 100%) that the highest elevations will see at least an inch of snow during this week's showers.

On Tuesday, snow could accumulate down to 11,000-12,000 feet or so, and on Wednesday into Wednesday night, snow may accumulate down to 9,000-10,000 feet or so. This will be low enough so that some ski areas will see snow on their runs and many mountains will be dusted in white.

The coldest air should arrive later Wednesday into Wednesday night, though some models show that this is NOT when we'll have the best chance for the most precipitation. That means that things may not line up perfectly for higher snow totals, so I'm keeping my snowfall hopes on the lower side, maybe just a few inches across Tuesday and Wednesday and generally at higher elevations.

From Thursday, September 30 through the following week, the weather pattern looks mixed. There will be plenty of time with dry weather, though lingering moisture could mean that we'll see a chance for showers nearly every day, especially over Colorado's southern and eastern mountains.

Now that we're heading into October, it's becoming more likely that we'll see colder and snowier storms, so I am keeping an eye on the longer-range forecast to see when we might enjoy our first winter-like system.

The fun news is that all three major long-range forecast models – the European, American, and Canadian ensemble forecasts – show the chance for a colder and stronger storm moving into the western United States early during the week of October 11th. This is about fifteen days away, so we should not trust the details of the forecast, but when all three major long-range forecast models show about the same outlook fifteen days from now, that's a sign that we should at least pay attention. Below is the forecast from the average forecast from 51 versions of the European ensemble model.

In non-weather news, I have a few in-person talks scheduled from mid-October through early November and I am working with sponsors and venues to make these in-person events as safe as possible to attend. I'll offer dates, times, and locations in upcoming posts.

Look for additional posts this week as we track the incoming higher-elevation snowfall.

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