Tomer’s Take: Snowfall continues to trend down for CA and the Interior Rockies 11/13-11/18. Trough trajectory and weak atmospheric river (AR) intensity are two limiting factors. A larger trough of low pressure across the West might be possible after 11/18. That said, heavy snow is likely for BC and higher elevations of the PNW with a couple feet of accumulation possible.

Clear Opening Day morning at Loveland Ski Area. Colorado is in for a 7-10 day dry stretch. I’m not forecasting any significant snow until 11/18 or later.

Heavy snow starts this afternoon/tonight in Whistler/Blackcomb and continues all night into 11/11. A 2nd burst of snow likely PM 11/12 and AM 11/13. Morning cam:

Current Setup

Water vapor satellite shows a large trough of low pressure hitting AK, BC and eventually PNW.

Orange/red = drier air aloft.

Forecast Atmospheric River

Forecast Integrated Vapor Transport (IVT) for 38N/123W (San Francisco coast) next 10 days. Notice one spike in intensity then a low level of contribution.

Forecast Jet Stream

Valid 11/15. Trough is further West off CA coast versus previous forecast solutions.

Valid 11/19. Exciting area of low pressure through CO/NM plus active jet in PNW with developing trough.

Forecast Snowfall

*Update 2pm 11/10.

Valid 11/10-11/13 mid-mountain. Big totals in BC/PNW higher terrain.

*Update 2pm 11/10.

Valid 11/14-11/18 mid-mountain.

Tomer’s Take: The next pattern shift continues to trend weaker on/after 11/13-11/18 for CA and the Interior Rockies. The main beneficiaries of heavy snow are ski areas in the PNW/BC. Optimism three to four days ago for heavy snow was predicated on a moderate to strong intensity atmospheric river (AR) contribution. That does not appear to be realistic now.

A few inches of new snow fell at Loveland, A-Basin, and Vail. Spectacular view from Vail this morning:

Current Setup

Infrared satellite shows a large trough of low pressure hitting AK, BC, and eventually the PNW.

Forecast Atmospheric River

Forecast ECMWF Integrated Vapor Transport (IVT) valid for the San Francisco lat/lon only favors weak AR contribution.

Forecast Jet Stream

Valid 11/15. A large trough of low pressure dives south from the PNW/BC towards the CA coast.

Valid 11/18. An area of low pressure exits through CO/NM. A powerful jet stream continues to favor the PNW/BC.

Forecast Radar & Satellite

Forecast Snowfall

*Update 2pm 11/9.

Valid 11/9-11/12. Heavy snow is likely in BC/PNW.

*Update 2pm 11/9.

Valid 11/13-11/17.

Tomer’s Take: Light to moderate snow is likely across Colorado’s mountains on 11/8-11/9 along with colder air. Then the Western pattern shifts with a large trough diving south from PNW/BC into CA on/after 11/13. The overall snowfall trend is down versus yesterday with less atmospheric river contribution.

7 inches of new snow in the last 24 hours at Park City, UT. Live view:

Current Setup

Infrared satellite shows the lurking trough and deep area of low pressure over the North Pacific. This will shift the Western Pattern.

Forecast Jet Stream

Valid 11/14. Notice the dip in the jet and area of low pressure off the CA coast.

Valid 11/17. The trough translates into the interior Rockies including UT, WY, CO.

Forecast Atmospheric River

The ECMWF is not as optimistic about the AR contribution versus 11/7.

Forecast Radar & Satellite

Forecast Snowfall

*Updated 2pm 11/8.

Valid 11/8-11/10. Light to moderate snow accumulation in CO.

*Updated 2pm 11/8.

Valid 11/11-11/7. Notice the substantial decrease in forecast snow for the Sierra and interior. A lack of an atmospheric river component is a big reason.

Tomer’s Take: Snow is falling across the Wasatch today then Colorado gets light to moderate accumulation 11/8-11/9. A much more significant pattern shift occurs on/after 11/13. A deep trough starts in the PNW/BC then digs south through CA with impressive snow totals and colder air. An atmospheric river (AR) component is also possible along with Subtropical Jet involvement. Snow from this setup would likely spread throughout the interior West including UT, CO, and WY.

My forecast video 4:45pm 11/7:

3-6 inches of snow is likely in Big and Little Cottonwood Canyons, UT with a glancing blow from a cold front.

It’s currently snowing at Alta:

Current Setup

Water vapor satellite shows an active jet pattern running off the North Pacific.

Forecast Jet Stream

Valid 11/14. Deep trough digging south from PNW into CA with big totals possible.

Valid 11/16. Jet flattens and becomes moisture conveyor-belt for interior Rockies.

Valid 11/15. Forecast mid-tropospheric atmospheric pressure anomalies show a deep area of low pressure off the West Coast. Anomalies run three standard deviations below the 30-year normal.

Forecast Atmospheric River

Valid next 10 days at 38N/123W (near San Francisco), Integrated Vapor Transport (ITV). Notice the sharp uptick in forecast moisture on/after 11/13.

Forecast Radar & Satellite

Forecast Totals

*Updated 2:45pm 11/7.

Valid 11/7-11/10 mid-mountain. Colorado’s snow occurs 11/8-11/9.

*Updated 2:45pm 11/7.

Valid 11/11-16 mid-mountain. The bulk of this snow occurs on/after 11/13.

Tomer’s Take: The final storm system in this cycle is moving into the PNW/BC. Overrunning light to moderate snow continues across the Tetons through this afternoon then the pattern dries out for a few days. This storm brushes UT on 11/7 with light accumulation, and hits CO on 11/8-11/9 with light to moderate accumulation. All forecast snow totals are trending down in WY, UT, CO.

After brief high pressure ridging on 11/12, the pattern shifts and a large trough of low pressure slides into the West Coast. The Subtropical Jet becomes involved. See forecast jet below. This pattern initially favors the PNW/BC for heavy snow then it shifts south and hits CA.

My forecast video:

Current Setup

Water vapor satellite shows the remaining area of low pressure moving into the PNW/BC.

Forecast Jet Stream

Valid 11/8. Dip in the jet with storm system moving through the Intermountain West.

Valid 11/15. New pattern. Large trough of low pressure sliding south from PNW/BC into CA with heavy snow totals and colder air. Subtropical jet also starts interacting.

Valid 11/15 middle of the atmosphere. Notice the low pressure anomalies off the West Coast. This would deliver snow and colder air.

Forecast Radar & Satellite

Forecast Snowfall

*Updated 2pm 11/6.

Valid 11/6-11/9 mid-mountain.

*Updated 2pm 11/6.

Valid 11/10-11/14 mid-mountain. Heavy snow possible around Tahoe 11/14-11/15. Heavy snow through BC 11/10-11/14.

Tomer’s Take: I’m forecasting 2-3 different storm systems through 11/11. Snow brushes UT on 11/7 and tracks through CO on 11/8-11/9.

Forecast Jet Stream

Valid 11/8. Notice the dip in the jet over UT/NV/WY. This is the storm system that brushes UT and tracks through Colorado.

Valid 11/11. Storm track favors the Northern Tier.

Forecast Radar & Satellite

Forecast Snowfall

Valid 11/4-11/7 mid-mountain. Snow brushes UT 11/7.

Valid 11/8-11/11 mid-mountain. Snow tracks through CO 11/8-11/9.

Tomer’s Take: Two storm systems are lined-up through 11/10. One additional moderate intensity atmospheric river (AR) surge occurs 11/5 in the PNW/BC then it concludes. Utah and Colorado get light to moderate snow accumulation 11/7-11/8.

My forecast video:

Current Setup

Water vapor satellite shows both storm systems over the Pacific and AR flow.

Orange/red = drier air aloft.

Forecast Jet Stream

Valid 11/11. The AR is done.

Forecast Radar & Satellite

Forecast Snowfall

*Updated 2:30pm 11/3

*Updated 2:30pm 11/3

Snow in UT & CO occurs 11/7-11/8.

Forecast Snowfall Timeline ->

Teton Range, WY:

11/3: AM 2″

11/4: Late 1″

11/5: AM 3″

11/6: PM 3″

11/7: 2″

Tomer’s Take: Three different storm systems loaded with Atmospheric River (AR) moisture hit the PNW/BC through 11/10 with overrunning snow in Banff, MT, and WY. The Tetons are in good position for heavy snow accumulation.

My forecast video:

Current Setup

Water vapor satellite shows all three areas of low pressure lined up.

Atmospheric River

Forecast atmospheric precipitable water shows a dragon’s breath of moisture stretching all the way back past Hawaii. This is the River.

Forecast Jet Stream

A powerful west to east oriented jet acts like a conveyor belt for moisture transport.

Forecast Rain/Snow Line

Teton Range, WY (Min/Max):

11/2: 7400/9500

11/3: 7900/8700

11/4: 8200/9400

11/5: 5900/8700

11/6: 5100/7700

11/7: 4400/6600

Forecast Radar & Satellite

Forecast Snowfall

Forecast Snow Timeline

Teton Range, WY:

11/2: PM 7″

11/3: AM 4″

11/4: PM 2″

11/5: 3″

11/6: 2″

11/7: 4″

11/8: 1″

Tomer’s Take: Three separate storm systems hit the PNW through 11/9. The first two storm systems deliver a moderate surge of atmospheric river (AR) moisture. Overrunning snow is likely in Banff, MT, WY, and eventually UT and CO although to a lesser degree. Snow levels in the PNW start high.

My forecast video:

Sunrise this morning at Loveland Ski Area, CO.

Sunrise this morning from Arapahoe Basin, CO.

Current Setup

Water vapor satellite shows the inbound AR.

Red/orange = drier air aloft.

Forecast Atmospheric River

Forecast Integrated Vapor Transport (IVT) for the PNW. Notice the two distinct moderate intensity surges with a trailing weak intensity signature 11/6-11/7.

Forecast Rain/Snow Line

Washington State (Min/Max):

11/1: 9200’/10800′

11/2: 6600/8900

11/3: 7100/9500

11/4: 6700/8000

11/5: 5900/6900

Forecast Jet Stream

The jet stretches back to near Hawaii acting like a moisture conveyorbelt.

Powerful jet orientation.

Forecast Radar & Satellite

Forecast Snowfall

*Updated 2pm 11/1.

*Update 2pm 11/1.

Snow Timeline

Teton Range, WY:

11/2: PM 3-4″

11/3: AM 5-6″

11/5: 4-8″

11/6: PM 3-6″

11/7: PM 1″

11/8: 2-3″