Tomer’s Take: Heavy snow is falling across VT, NH, ME through 12/17. Then the pattern gradually shifts to favor the PNW/BC and northern tier of states. By Christmas a NW flow might develop to include CO.

My forecast video 12/16:

Current Western Snowpack

It resembles a La Nina pattern but with a slight shift south/west. California has benefited from 2-3 AR events with some subtropical jet involvement.

In CO, it’s mostly La Nina with a shift west/NW.

Current Setup

Water vapor satellite shows a fast, moisture-starved jet stream cutting through the Intermountain West. Most of the action is in the NE with a trough.

Orange/red = drier air aloft.

Forecast Pattern through Christmas

Forecast jet stream valid 12/17/2022. Benign pattern for most of the West.

Forecast jet stream valid 12/25/2022. This pattern supports a NW flow for MT, WY, CO.

Forecast Timing

Forecast radar/satellite valid 12/16-12/21.

Forecast Totals

Forecast snow totals (inches) valid 12/16-12/18. Most of the West is quiet except for PNW/BC/Banff.

Forecast snow totals (inches) valid 12/19-12/22. Strong jet flow generates moderate to heavy snow PNW/BC, ID, MT, WY.

Forecast snow totals (inches) valid 12/23-12/25. A NW flow might develop for MT, WY, CO.

Forecast snow totals (inches) valid 12/16-12/18.

Forecast snow totals (inches) valid 12/19-12/25. The bulk of this snow occurs with a potential storm system on/around 12/23.

Tomer’s Take: Heavy snow is on track for the Northeast 12/16-12/17. Then the pattern shifts back to the PNW/BC/Banff and eventually WY, CO, UT. An Arctic front is the catalyst for shifting the pattern back to the West on/after 12/20.

My forecast video 12/15:

Season Totals so far

I put this together as of 12/15.

Current Setup

Water vapor satellite shows the Western blizzard tracking towards the Northeast. In Pacific, two low pressure systems are meandering waiting to be picked up. An Arctic front appears to pick both storm systems up on/after 12/20.

Northeast Snowstorm

Forecast jet stream valid 12/16. The Western blizzard is riding a powerful jet stream into the Northeast.

Forecast snow totals (inches) valid 12/15-12/19.

Forecast Pattern

Forecast jet stream valid 12/16. A quiet period for the West except for some light snow accumulation with a fast northerly flow and Clipper.

Forecast jet stream valid 12/24. Big dip in the jet on the East side of the Rockies with Arctic air.

Forecast Timing

Forecast radar/satellite valid 12/15-12/20.

Forecast Totals

Forecast snow totals (inches) valid 12/15-12/17.

Forecast snow totals (inches) valid 12/18-12/23.

Tomer’s Take: The Western blizzard turns into a large snowstorm for the Northeast 12/16-12/17. Out West, the pattern settles down with only light snow accumulation through 12/19 then turns more active 12/20-12/22+ as two Pacific storms catch a fast northern branch.

• Alta, UT is reporting 50″ between 12/10-12/14.
• Winter Park, CO is reporting 10″ in 48 hours.
• Aspen Mountain, CO is reporting 15″ in 48 hours.
• Wolf Creek, CO is reporting 13″ in 48 hours.
• Buffalo Pass, CO about 24″ between 12/10-12/14 (1.6″ SWE).
• Avalanche Warnings are in effect for parts of Colorado’s mountains. Ingredients include a foot or more of new snow (in the last 4 days) plus consistent 30-70mph wind gusts and both a persistent slab and storm slab risk.

My forecast video 12/14:

Current Setup

Water vapor satellite shows the Western blizzard slowly working its way through the Dakotas. Its destination is the Northeast.

You’ll also notice two low pressure’s in the Pacific. The southern low is cut-off from the northern branch but might get picked up 12/20-12/22 by a Canadian cold front/trough. The 2nd low might also get picked up around 12/22 or later.

Forecast Pattern

Forecast jet stream valid 12/15/2022.

Forecast jet stream valid 12/22/2022.

The two low pressure systems in the Pacific might get picked up by the Northern Branch and escorted into the West Coast.

Out East, a large dip in the jet dominates the pattern supporting additional snow.

Northeast

Forecast jet stream valid 12/16/2022.

Notice the powerful jet stream escorting the Western blizzard into the Northeast.

Forecast snow totals (inches) valid 12/15-12/19. Most of the big resorts get a foot or more.

Forecast Timing

Forecast radar/satellite valid 12/14-12/19.

Forecast Totals

Forecast snow totals (inches) valid 12/14-12/16.

Forecast snow totals (inches) valid 12/17-12/22.

Tomer’s Take: 21-30 inch Sierra totals so far with snow continuing. Next stop is ID, WY, MT, UT, and CO for big totals through 12/15. Then pattern turns more tranquil after 12/15. Active pattern shifts to the Northeast.

Current Setup

Water vapor satellite shows the big low moving at snails pace through CA. Red/orange = drier air aloft.

Forecast Pattern

Forecast jet stream valid 12/12/2022. The slow movement of the low through the trough generates three days worth of snow accumulation and wraparound snow in parts of MT, WY, and C+N zones of CO.

Forecast jet stream valid 12/13/2022.

Forecast jet stream valid 12/20/2022. The pattern is much quieter across the West with only a fast-moving low on the northern branch with light accumulation.

Forecast Timing

Forecast radar/satellite valid 12/11-12/16.

Forecast Totals

Forecast snow totals (inches) valid 12/11-12/15.

Forecast snow totals (inches) valid 12/16-12/19.

Forecast snow totals (inches) valid 12/12-12/19. Most of this snow accumulation occurs with a larger storm system on 12/16-12/17.

My forecast video 12/11:

Tomer’s Take: California’s Sierra continues to get nailed by a strong storm system, a moderate atmospheric river (AR), and solid orographics. Next stop for big totals are ID, UT, WY, CO 12/11-12/14.

• I was alerted to heavy snowfall at Sunshine Village between 12/7-12/9 of about 20 inches. This is more than what I was forecasting. Curious as to how it occurred. I’ll look into the pattern.

Current Setup

Visible satellite shows the big low pressure hitting California.

Here’s a zoom. The size is impressive!

Forecast Pattern

Forecast jet stream valid 12/11/2022.

Forecast jet stream valid 12/12/2022. Look at the size of the trough and ejection.

Forecast jet stream valid 12/13/2022. The main low ejects and the 2nd low is meandering through the Pacific with little impact.

Forecast jet stream valid 12/18. A quiet period for the West with in-between jet flow. The northern and southern jet branches are split and running parallel.

Forecast Timing

Forecast radar/satellite valid 12/10-12/15.

Forecast Totals

Forecast snow totals (inches) valid 12/10-12/15. The heavy snow in Colorado occurs over the course of 3-4 days (so it’s not all at once).

Forecast snow totals (inches) valid 12/16-12/18. A much quieter period in-between jet flow.

My forecast video:

Tomer’s Take: The next storm system is a powerhouse 12/10-12/13. It has jet support, colder air, and a weak to moderate atmospheric river (AR) contribution.

• A smaller low is currently sliding through the Intermountain West and washing-out.
• An Alberta Clipper races in behind the big storm system on 12/14-12/16 with additional light accumulations in Banff, ID, MT, WY, UT, CO.

Current Setup

Infrared satellite shows a small low washing-out across the Intermountain West followed by the much stronger storm system over the Pacific.

Forecast Pattern

Forecast jet stream valid 12/10/2022.

Forecast jet stream valid 12/12/2022. Impressive jet stream pattern with large trough and ejecting low.

Forecast jet stream valid 12/18/2022. After the big storm system the West turns drier. By 12/18, there are two lows meandering through the Pacific.

Forecast Timing

Forecast radar/satellite valid 12/9-12/14.

Forecast Totals

Forecast snow totals (inches) valid 12/9-12/13.

Forecast snow totals (inches) valid 12/14-12/18.

My forecast video:

Tomer’s Take: A powerful storm system arrives 12/10-12/13. I’m forecasting a weak to moderate atmospheric river (AR) for the Sierra, colder air, and widespread heavy snow for the PNW, ID, WY, UT, and CO.

• 10″/24hours at Mount Baker.
• 6″/24hours at Wolf Creek. 17″ storm total.
• 5″/24hours at Purgatory. 15″ storm total.
• 4″/24hours at Alta. 154″ season total.

Current Setup

Water vapor satellite shows two storm systems lined-up in the North Pacific. The 2nd storm system approaching the Bering Sea is the powerful storm system slated for the West 12/10-12/13.

Orange/Red = drier air aloft.

Forecast Pattern

Forecast jet stream valid 12/9/2022. Storm #1 hits the West Coast then washes-out as it hits the interior Rockies.

Storm #2 is stronger with better jet support and colder air. It also delivers a weak to moderate atmospheric river (AR) to CA’s Sierra.

Forecast Jet stream valid 12/13/2022. A third storm system is meandering.

Forecast jet stream valid 12/17/2022. Storm #3 drops really far to the south. Most of the West is dry.

Forecast Timing

Forecast radar/satellite valid 12/8-12/13.

Forecast Totals

Forecast snow totals (inches) valid 12/8-12/10.

Forecast snow totals (inches) valid 12/11-12/13.

Forecast snow totals (inches) valid 12/14-12/17.

Tomer’s Take: Snow continues to fall in parts of Colorado ending on 12/8. Two additional storm systems are lined-up through 12/16 with heavy snow accumulation for the West and a weak atmospheric river (AR) setup for CA.

->Snowmass, CO is reporting 15″ in the last 48 hours.

->Wolf Creek, CO is reporting 11″ in the last 48 hours.

->Jackson Hole, WY is reporting 7″ overnight and 17″ in the last 48 hours.

Current Setup

Water vapor satellite shows the next two areas of low pressure lined-up in the Pacific. The third low is cutoff from the main flow.

Red/orange colors = drier air aloft.

Forecast Pattern

Forecast jet stream valid 12/8/2022. You can see storm #1 and storm #2.

Forecast jet stream valid 12/16. A new trough of low pressure approaches the CA coast.

Forecast Timing

Forecast radar/satellite valid 12/7-12/12.

Forecast Totals

Forecast snow totals (inches) valid 12/7-12/9.

Forecast snow totals (inches) valid 12/10-12/12.

Forecast snow totals (inches) valid 12/13-12/16.

My video forecast 12/7:

Tomer’s Take: I’m forecasting four different storm systems for the West through 12/15 with big totals. A weak atmospheric river (AR) is possible for CA’s Sierra 12/10-12/11.

• Storm #1 continues to gradually move from CA into the interior Rockies. Waves of snow are riding the jet into UT, WY, CO.
• Storm #2 hits the West Coast on 12/8 then proceeds to wash-out while spreading snow into the interior including ID, BC, WY.
• Storm #3 between 12/10-12/13 is a powerhouse with weak AR contribution.
• New 24 hour snow totals: Vail 6″, 3″ Alta, 3″ Kirkwood, 10″ Jackson Hole, 5″ Steamboat, 2″ Breckenridge, 8″ Loveland.

Current Setup

Infrared satellite shows an active flow off the Pacific with storm systems lined-up.

Forecast Pattern

Forecast jet stream partner valid 12/7. Storm #1 is moving at snails pace. Storm #2 is inbound the PNW.

Forecast jet stream valid 12/15. Storm #4 is sliding through WY/CO. Ridge rebuilds across West Coast.

Forecast Timing

Forecast radar/satellite valid 12/6-12/11.

Forecast Totals

Forecast snow totals (inches) valid 12/6-12/8.

Forecast snow totals (inches) valid 12/9-12/12. This is a big period for CA, UT, ID, WY, SW CO. Storm #2 hits the PNW then washes out. But, storm #3 is a powerhouse with a weak atmospheric river contribution.

Forecast snow totals (inches) valid 12/13-12/15. Another big period for CA.

My forecast video for 12/6:

Tomer’s Take: A three storm combo remains in my forecast through 12/12 with heavy grand totals across the West. A forth storm system is possible on 12/13-12/14.

• Storm #1 is moving at snails pace and continues pushing snow into the Sierra and also interior Rockies of UT, WY, and CO through 12/7.
• Storm #1 has a few bullseyes in the Colorado including Crested Butte, Vail, Steamboat, Wolf Creek, Silverton, and Purgatory.
• Storm #2 12/8-12/9 is trending weaker especially for CA, UT, WY, CO.
• Storm #3 12/10-12/12 is stronger and colder.
• Alta and Snowbird are reporting 8-9 inches in the last 24 hours. Jackson Hole is reporting 6 inches in the last 24 hours.
• Mammoth Mountain is reporting 5.5 feet of snow so far this December.

Snow is also falling in Colorado where it’s just getting started. A 3.5 day prolonged period of focused snow is in my forecast with over a foot for a few locations.

Loveland’s view is shrouded this morning:

Current Setup

Infrared satellite shows the storm systems lined-up in the Pacific. Storm #1 is very slow moving in a deep trough.

Forecast Pattern

Forecast jet stream valid 12/6/2022. Very slow moving low pressure in a deep trough.

Forecast Jet stream valid 12/13/2022. The storm track has shifted further north favoring the PNW, BC, Banff and northern tier of the Rockies. Potential storm #4 inbound.

Forecast Timing

Forecast radar/satellite valid 12/5-12/10.

Forecast Totals

Forecast snow totals (inches) valid 12/5-12/7. Notice the bullseyes in Colorado.

Forecast snow totals (inches) valid 12/8-12/13.