I took the skis for a walk early this Saturday morning. It was my first time skinning this season. Snow coverage remains thin across the Front Range high peaks of Colorado. Colorado needs snow.
Out early with the moon.
Tomer’s Take
2-3 different storm systems lined-up for the West through Christmas.
A large dip in the jet stream might develop Christmas week off the coast of California.
A weak to moderate intensity atmospheric river is possible for the High Sierra from Shasta to Tahoe to Mammoth.
This flow will send snow into the Interior Rockies including UT, ID, WY, and CO. 1-2 feet likely at many ski areas in UT and WY. In CO, the Western Slope ski areas are favored.
My forecast video includes a two-part snow forecast and explanation of the storm track.
It’s a powder Friday in Utah’s Wasatch with 6-13″ new in the last 24 hours.
Light to moderate snow continues in the Tetons through Friday night.
Light snow accumulation in the Central and Northern Mountains of Colorado on Friday.
3 storm systems lined-up for the West Coast through Christmas with heavy snow accumulation in CA, OR, WA, and B.C..
There appears to be weak to moderate atmospheric river influence in the PNW and CA during this storm cycle.
Let’s take a closer look at the Wasatch. Alta’s season total just surpassed 60″. According to Professor Jim Steenburgh at the University of Utah this is important.
.@AltaSkiArea cracking the 60 inch snow depth officially begins the start of "good early season conditions" per my personal snow snobbery. pic.twitter.com/umEbWzTfDx
I almost attended the University of Utah for meteorology but ultimately chose Valparaiso University. I was honestly worried I would ski and climb too much!
Let’s take a look at the storm track. It’s loaded with storm systems for the West Coast through Christmas. You can see the storm system sliding through Utah, Wyoming, and Colorado this morning.
Infrared satellite with storm track 12/17/2021 5am.
Let’s look at the Christmas pattern. There is a significant drop in atmospheric pressures and dip in the jet stream 12/22-12/25 across the West. Notice the red low pressure off the West Coast.
It turns out this was no ordinary windstorm on 12/15/2021. Based on the evidence, it appears air from the Stratosphere was pulled all the way down to Denver. In Synoptic-Dynamic Meteorology this is called Tropopause Folding. It also means the jet stream descended almost to the valley floor generating those destructive 100mph+ gusts and dust storm.
Credit for this sharp visual goes to Dr. Mathew Barlow:
Intense shortwave brings dynamic tropopause and jet stream nearly to the surface in the lee of the Rockies pic.twitter.com/KwNUwO1iMS
I had to look back in my college Synoptic-Dynamic Meteorology textbook and re-read the chapter on fronts and jets. I can’t remember such a textbook example in my Colorado forecasting tenure.
A few key points:
We live in the Troposphere (the lowest part of the atmosphere).
The Tropopause is the top of the Troposphere, like a blanket on top.
The Stratosphere is the next layer vertically up in the atmosphere above the Troposphere.
Folding the Tropopause is a big deal.
A good visual from my college textbook:
Vertical layers of the atmosphere.
Folding of the Tropopause requires strong vertical wind sheer, normally along a front with powerful jet.
This folding opens the door for Stratospheric air to mix down into the Troposphere where we live.
Evidence of folding
Ozone levels are higher in the Stratosphere, so a true intrusion would mix higher ozone levels down to the surface.
And what do we find on 12/15/2021? Code Yellow for Ozone.
Ozone levels this high in December are an anomaly.
It was also forecast by the RAP-Chem model. Look at this intrusion!
RAP-Chem Ozone model forecast.
Also of note, there is some concern that aside from ozone mixing down, that radioactive debris from nuclear weapons can mix down. This is a concern in my textbook and something to ponder.
I’m forecasting 3-4 different storm systems through Christmas for California’s High Sierra from Shasta to Tahoe to Mammoth.
Two of the storm systems next week could have atmospheric river influence.
I’m forecasting three different storm systems through Christmas for the Pacific Northwest.
A storm system could hit the Intermountain West (ID, UT, WY, MT, CO) around Christmas (12/23-12/25).
Look at the active storm track over the Pacific Ocean.
Infrared satellite with storm track, 12/16/2021 5am.
Snow is falling across California’s High Sierra Thursday morning. Here’s the view at Mammoth Mountain.
Mammoth Mountain Village cam 12/16/2021.
If the atmospheric river (AR) does influence California’s storm systems next week then we could be looking at significant snow. The latest integrated vapor transport forecast does indicate weak to moderate AR intensity 12/20-12/22.
IVT forecast 12/16/2021.
Wind
Wednesday delivered severe wind to Colorado. Gusts ranged from 60-112mph+. Looking ahead, my wind gust forecast is more reasonable on Colorado’s 14ers.
Tomer 14er wind gusts forecast 12/16/2021.
Snow Forecast
Let’s break my snow forecast down into two time-frames.
12/16-12/19:
Inches of snow 12/16-12/19.
12/20-12/25:
Inches of snow 12/20-12/25.
Drilling down, here’s my snow plume forecast for Mammoth Mountain, CA through Christmas.
It’s been an incredibly windy day in Colorado. A snow squall line developed in the San Juan Mountains and then raced north to the I-70 Corridor then into Denver. A 112mph gust was recorded over the San Juan Mountains near Red Mountain Pass. Dale Garland sent me a note on how windy and snowy it was in Silverton. Then Bryon Powell posted this video.
Silverton, CO whiteout 12/15/2021.
I take a look at what’s next on the storm track in my mountain weather forecast video. I look all the way out to Christmas.
Storm systems are lined-up in the Pacific for the next 8-10 days.
The storm track stays active into Christmas across the West Coast.
The atmospheric river storm system continues Tuesday in California’s High Sierra then it slides into ID, UT, WY, MT, and CO with moderate to heavy snow accumulation and very strong wind.
A second faster moving, smaller storm system moves into the West Coast on Wednesday-Thursday then Intermountain West Thursday-Friday.
The current storm track on infrared satellite.
Infrared satellite 12/14/2021 5am.
I’m forecasting very strong wind Tuesday-Wednesday in Utah, Wyoming, and Colorado as a 140mph jet streak moves through. In fact, I think we could see gusts to 120mph in parts the Sangre De Cristo Mountains of Colorado. Here’s a 14er snapshot:
Tomer 14er wind gust forecast 12/14/2021.
Christmas Pattern
Pressure anomalies are possible across the West Coast. This could mean snowfall for the High Sierra to the Cascades on/around Christmas.
Looking way down the road to 12/25, the pressure pattern shows significant pressure anomalies over the West Coast. This could mean heavy snow for the Pacific Northwest and the Sierra (and potentially the interior Rockies thereafter).
Another 1-2 feet in the Pacific Northwest as the atmospheric river (AR) continues into Monday.
The AR then sinks south into California’s High Sierra with 40-70 inch totals 12/12-12/14 from Shasta to Tahoe to Mammoth. The biggest totals will be above 5,000′. The higher the better.
That storm system then breaks loose and delivers widespread 1-2 foot snow totals to the Interior Rockies of UT, ID, WY, MT, and CO between 12/13-12/15.
In Colorado, I’m forecasting the biggest totals of a foot (or slightly more) 12/14-12/15 at the Western Slope ski areas including Aspen/Snowmass, Crested Butte, Wolf Creek, Silverton, Purgatory, and Telluride. Less Vail east into Summit County and at the Tunnel, 5-10″.
A smaller, faster moving storm system swoops in on the heals of the AR and delivers another 6-12 inches to the High Sierra. Grand Totals by 12/17 reach 50-90 inches.
For more analysis, my forecast snow totals, and Mammoth snow plume here’s my forecast video:
I started this Saturday off with a fantastic workout in the Foothills of Colorado. This time I was greeted my much colder temps and an inch of snow on parts of the trail. I also bumped into my friend Justin Becker and we finished the trail run together. Great seeing and chatting with him!
Forecasting delight.
Atmospheric River
Tomer’s Take
A weak to moderate intensity atmospheric river (AR) continues to deliver heavy snow (25-40 inches) to the high volcanoes and high Cascades of the Pacific Northwest today and tapers-off on Sunday.
This AR then slides south and nails California’s High Sierra.
The key elevation looks to be 5000′. Stay above that for several feet of snow accumulation 12/12-12/14.
This storm system then breaks loose and delivers 1-2 feet of snow accumulation to parts of Utah and Colorado 12/14-12/15.
In Colorado, I like the Western Slope ski areas (again) for the most snow accumulation 12/14-12/15.
Idaho, SW Montana, and Wyoming all get snow as well.
Here’s my forecast video with more analysis and two-timeframe snow forecast the West.
The forecast for 1-2 feet materialized across parts of Colorado and Utah.
Weak to moderate atmospheric river hits Pacific Northwest Friday night-Saturday with 25-50 inches.
Weak to moderate atmospheric river hits California’s High Sierra 12/12-12/14 with 40-80 inches.
That storm system then breaks loose and hits Utah, Idaho, Wyoming, SW Montana, and Colorado 12/14-12/15.
Seeing these snowstake cams brings a smile to my face. We needed this snow so bad.
Crested Butte 12/10/2021 4:30am.Aspen Highlands 12/10/2021 5am.Wolf Creek, CO 12/10/2021 5am.
This Weekend
A storm system loaded with a weak to moderate intensity atmospheric river hits the Pacific Northwest between Friday night and Saturday. 25-50 inches of total snow possible on the high volcanoes and high Cascades including Bachelor, Timberline, Stevens Pass, Whistler/Blackcomb, and Mount Baker.
Then, this storm system then sinks south and hits California’s High Sierra with 40-80 inches between Sunday and Tuesday. This includes Shasta, Tahoe, and Mammoth. Here’s the integrated vapor transport forecast for Central California showing the weak to moderate intensity atmospheric river 12/12-12/14.
