Never miss a beat! Receive The Colorado Daily Snow via email the moment it's written. Start your FREE OpenSnow Super Pro trial today!
This storm is very exciting. It's also making me lose my hair faster than normal (thanks dad!).
After looking at today's latest weather models, I'm not making any big changes to the forecast. Here's my best guess for the timing of the heaviest snow:
North of I-70 to Wyoming border: Tuesday noon through Wednesday sunrise.
Aspen & I-70: Tuesday sunset through Wednesday midday.
Irwin, Crested Butte, Monarch: Tuesday evening through midday Wednesday.
Telluride, Silverton, Durango, Wolf Creek: Wednesday sunrise through Wednesday sunset.
Front range cities & Foothills: Tuesday afternoon through all of Wednesday.
As I talked about this morning, the biggest question is where the cold front stalls. Wherever this happens, snowfall amounts are going to be huge. The models think it could happen somewhere between Aspen to the south and Steamboat to the north. Of course this range includes many of the ski areas in the state, which is why my forecast shows heavy snow for most areas.
It'll be impossible to predict the exact location of the front until it actually stalls, so we'll have to wait and see. Watching a storm like this come together is more fun than watching the movie Gravity (which, by the way, was an amazing display of cinematic technology).
With the jet stream overhead, ridge-top winds will be strong Tuesday night into Wednesday morning, and I expect this combination of strong winds and heavy snow to close some roads late Tuesday night or Wednesday morning. Wednesday will be a big day for snow, but due to winds, cold temperatures, heavy snow, and potential new terrain opening, the best time to ride might be Wednesday midday / afternoon or even Thursday morning. Of course first-chair on Wednesday is never a bad call if you can swing it, I'm just saying that there might be stashes around for a while.
For those of you in Boulder, come say hi on Thursday night as I'll be giving a short talk at 8pm to open for Jason McGowin's (La Sportiva) show, "Skiing Light and Fast in the Backcountry."
I'll write another update late tonight if something new pops up, otherwise look for the next post on Tuesday morning.
For the mountains, heavy snow late Tuesday afternoon through Wednesday afternoon with 10-18+ inches. Roads may close Tuesday night and Wednesday morning during the heaviest snow. For the front range, snow will fall from Tuesday evening through Wednesday morning with a couple inches of accumulation. Very cold air for the entire state Wednesday through the weekend with lows below zero and highs around 5-15 degrees. Welcome to winter!
The mountains along and north of I-70 saw snow last night with accumulations from a trace to 2 inches. Clouds, flurries, and a few snow showers will hang around this same area today on Monday and Monday night, but I do not expect any accumulations.
The main event will start on Tuesday and last through Wednesday afternoon. Areas that are further north like Steamboat will experience the snow earlier from about midday Tuesday through Wednesday sunrise. Central areas from I-70 down to Crested Butte will see the heaviest snow Tuesday evening through midday Wednesday. And southern areas around Telluride, Silverton, Durango, and Wolf Creek will see the heaviest snow from late, late Tuesday night through Wednesday evening.
I am confident that most locations will see heavy snow with accumulations around 10-18 inches from Tuesday afternoon through Wednesday. The powder day will be on Wednesday. See detailed forecasts for each mountain here: http://opsw.co/CO1-5
The upcoming weather pattern is absolutely perfect for heavy snow, and here's why.
First, we'll have plenty of moisture in the atmosphere to create snow.
Second, the wind direction at and above mountain top is from a west-ish direction, which means all mountains can see good snow because this wind gets lifted up by the mountains and rising air creates snow.
Third and most importantly, the atmosphere will lift the air in two additional ways. One way will be a cold front that stalls over northern and central Colorado. The front is like a wedge, forcing air to rise up and over the front. The second way is the jet stream, which will stay over Colorado for 36+ hours. Through some *fun* math equations, the fast moving air of the jet stream at 35,000 feet helps lift the air below it, and since rising air makes snow, this is also working in our favor.
I lack some confidence in the exact location of the heaviest snow and also in the exact timing of the storm.
The heaviest snow will fall along the stalled cold front. The models are not set on exactly where the front will stall, and we likely won't know this with confidence until the front is actually stalled. Modern weather forecasting technology is incredible, but it's not great with fine details like this. The overall setup is so good that I'm confident that most areas will see heavy snow, but some locations will see more than forecast if the front stalls longer near them, and other areas might get less if the front sets up in a different location. Right now the consensus of all models is that the front will stall somewhere around Aspen to I-70.
In terms of timing, the main inconsistency is that the American GFS and NAM models show lots of snow on Tuesday, while the often more accurate European and British models show the heaviest snow waiting to fall until Tuesday night. I leaned the forecast toward these slower models, but if they trend fasters, I'll update the numbers this afternoon for more snow on Tuesday.
The snow will clear out on Wednesday afternoon and evening. Then get ready for very cold temperatures lasting through the weekend. Lows will be below zero and highs will struggle to get about 10F.
We could see a bit more snow this weekend, most likely Saturday night and Sunday. More on this next storm later in the week.
The longer range looks pretty good with no large ridge to our west blocking storms. This isn't a promise for lots of snow, but it does point to the potential for a continued chances for storms every 3-5 days, and that's as much as we can hope for when looking at the 10+ day forecast.
Get your shovels, boards, and heaters ready because it's time to ride! Look for more terrain opening later this week and weekend...
This is a quick update on Monday morning ... I'll post a longer discussion in about an hour when I figure things out.
The storm on Tuesday afternoon through Wednesday afternoon will be a big snow producer, especially for central and northern Colorado. There will likely be a time Tuesday night or Wednesday morning when many roads could close due to heavy snow and strong winds.
The timing of the storm is what is giving me the headache.
The more accurate models are showing the heaviest snow falling Tuesday night through Wednesday midday.
The less accurate models are showing the heaviest snow falling Tuesday during the day through Wednesday morning. This is about 12 hours faster than the other models.
This 12 hour difference between the models in a 1-day forecast is HUGE and I can't remember the last time I saw this large of a discrepancy this close to a storm day.
From a skiing perspective, I don't think it matters that much as Wednesday is the day, though this is the difference between first chair being best or free refills. From a travel perspective, the timing will make a big difference.
Snow accumulations for the northern and central mountains could be 1-2 FEET if the cold front stalls across the area as forecast, and the valleys should also see heavy snow with 6-12 inches. If the front stalls in another spot or moves more quickly, amounts will be a bit lower, but still significant.
So overall this is great news ... I'm just working on the timing issues and will post again soon when (if?!) I get that figured out.
For northern Colorado's weak storm Sunday and Sunday night, look for less snow on Sunday than I thought but still a few inches Sunday night. During the week, expect heavy snow starting on Tuesday and lasting through Wednesday with double digit totals likely. It'll be very cold Wednesday night through the weekend, with another weak-to-moderate storm possible Saturday and Sunday.
I'll get to the big mid-week storm in just a second.
For Sunday and Sunday night, I'm still expecting snow for mountains along and north of I-70, but I lowered amounts on Sunday to just 0-1 inches because the stronger energy doesn't come through until Sunday night. Overnight there could be a few inches with northwest flow, and just a few flakes to an inch down to Aspen.
Monday and Monday night will be mostly dry across the state, though there might be enough lingering moisture across northern Colorado for flurries or light snow showers with minimal accumulation.
Then the fun begins on Tuesday and lasts through Wednesday night.
I'm confident that the mid-week storm will bring most areas double-digit snow accumulations and that it'll turn sharply colder by Wednesday night. If you add up my snow forecast for Tuesday, Tuesday night, and Wednesday, it shows amounts around a foot for most mountains. I'm confident in heavy snow because we have multiple factors coming together:
+ A cold front at the surface, which helps to lift the air.
+ The jet stream overhead, which helps to lift the air.
+ Ample moisture.
+ And all of these factors will last for about 18 hours.
I'm less confident in the timing of the storm. The more accurate European and British models are showing the brunt of the snow falling Tuesday night through the first half of Wednesday. The less accurate American model shows the heaviest snow falling on Tuesday afternoon and Tuesday night. Usually I'd trust the Euro and British models and forecast a later start to the storm, but the most recent European model run sped up a little from previous runs, and this lack of consistency leaves me hanging.
I don't think the timing issue matters much, as the deepest snow will be found Wednesday. The difference is if Wednesday first chair is the best, or if it keeps dumping through the day on Wednesday. We'll see. Usually this type of detail is finalized by the time the storm is three days away, but this storm is being tricky until the last moment.
Forecast snow amounts from the American GFS model for Tuesday through Wednesday. Source: WeatherBell.com
The front range and plains will see snow and cold air starting on Tuesday. Keep this in mind if you're heading to or from the flatlands.
By Wednesday night expect the coldest air of the season to arrive and last through the weekend. For the mountains, temperatures from Wednesday night through Friday will likely be below zero (F) at night and in the teens (at best) during the day. There will be very little moisture in this cold air, so look for scattered flurries with little accumulation on Thursday and Friday.
Another weak-to-moderate storm will zoom in from the northwest next weekend. Right now snow amounts don't appear to be too high, but the continued chilly air should make for high snow-to-liquid ratios, so any moisture we do get will be converted into light, fluffy snow.
There's no need to look at the forecast beyond a week when so much goodness is happening in the next seven days, so let's focus on the upcoming storms and then tackle the longer-range forecast down the road.
Light snow and wind for I-70 and north on Sunday and Sunday night. Heavy snow for all mountains late Tuesday night through Wednesday, with very cold temperatures Wednesday through the weekend.
After a week of quiet weather, we'll be back on the storm train very soon. In one week from now, it's going to look and feel like mid-winter.
We'll see a quick shot of snow Sunday morning through Monday morning, focusing on the mountains along and north of I-70. Total accumulations could be about 2-4 inches, with more in spots that do well in northwest flow. The models do not agree on the snow amounts (not a surprise considering northwest flow is rarely accurately predicted), so my confidence is low on the accumulation forecast. A few flakes to an inch or two might get south to Aspen, but this will mainly be an I-70 and north event. The heaviest snow will likely fall Sunday afternoon and Sunday night, with snow tapering to flurries by mid morning on Monday.
Monday afternoon through most of Tuesday will be dry as the big storm will still be to our northwest and west.
Look for increasing clouds, winds, and snow to arrive on Tuesday night. Some models show the snow starting to fall heavily Tuesday night, and others hold it off until Wednesday morning. But that's a small detail that doesn't matter much, because the take away is that we'll see heavy snow sometime in the Tuesday night through Wednesday afternoon time frame, with accumulations approaching a foot for many mountains by Wednesday night.
This storm has it all - pretty good moisture, cold temperatures, a strong cold front to kick the snow into high gear, and good vorticity (storm energy) to help lift the air. Because all of these factors are coming together, I have moderate to high confidence of heavy snow falling late Tuesday night through Wednesday.
Snow should taper off Wednesday evening as very cold air moves into Colorado. Expect lows to get close to or below zero later in the week with highs in the teens.
Forecast temperatures for late next week, showing very cold air over the Rockies. The four corners of Colorado are highlighted in pink dots. Note that the temperature scale is in Celsius. Source: Twisterdata.com
Snow is likely to be in the air from Thursday through next weekend. It's tough to get large snow accumulations when the temperatures are very cold because there's usually very little moisture in the air. But with a trough (area of cool and stormy weather) over the Rockies from late next week through next weekend, it's likely we'll see at least one or two shots of additional snowfall with decent accumulations.
All-in-all, this is a great forecast going into December!
View individual forecasts
- Arapahoe Basin
- Aspen Highlands
- Aspen Mountain
- Beaver Creek
- Berthoud Pass
- Cameron Pass
- Copper Mountain
- Crested Butte
- Echo Mountain
- Loveland Ski Area
- Purgatory at Durango Mountain Resort
- Rocky Mountain National Park
- Ski Cooper
- Ski Granby Ranch
- Winter Park
- Wolf Creek