Tomer’s Take: Pattern stays active with new snow for PNW/BC/MT/ID/WY/UT/CO/NOCA through 4/21, an additional storm system on/around 4/24, then pattern might transition to a ridge of high pressure late April into early May.

My forecast video 4/14:

Current Setup

Water vapor satellite shows the primary storm track from the Pacific into the PNW.

Forecast Freezing Level

Wasatch, Maximum Height:

4/14: 6600′

4/15: 9400′

4/16: 11500′

4/17: 11500′

4/18: 8400′

4/19: 7700′

Colorado’s Central Mountain Zone, Maximum Height:

4/14: 9900′

4/15: 8200′

4/16: 11700′

4/17: 12600′

4/18: 12100′

4/19: 10500′

Forecast Pattern

Forecast jet stream valid 4/23. Both jets are still active with one additional storm systems 4/23-4/24.

Late April Pattern

Forecast mid-atmospheric pressure anomalies (GEFS) valid 4/29. The high pressure ridge is unmistakable.

Forecast Timing

Forecast radar/satellite valid 4/14-4/19.

Forecast Totals

4/14-4/16:

4/17-4/23:

Tomer’s Take: Freezing levels fall today (4/13) through 4/15 then start rising again with warmer air. Storm track favors PNW/BC/Northern Tier through 4/24 then uncertainty.

One more photo of the dirty snowpack in Colorado…it’s a good one from Nick Green while skiing in Aspen, CO. Thanks Nick!

My blog post yesterday explains this phenomena.

Forecast Freezing Level

Wasatch, Maximum Height:

4/13: 6100′

4/14: 7100′

4/15: 9500′

4/16: 11700′

4/17: 11300′

4/18: 7200′

Colorado’s Central Mountain Zone, Maximum Height:

4/13: 12300′

4/14: 9700′

4/15: 8500′

4/16: 11900′

4/17: 13000′

4/18: 11900′

Forecast Pattern

Forecast jet stream valid 4/22. Northern branch remains active for the PNW/BC/Northern Tier.

Forecast Pattern Late April

Forecast GEFS mid-atmosphere pressure anomalies valid 4/24. This data keeps the unsettled pattern entrenched across the PNW/BC/Northern Tier through 4/24.

Forecast GEFS mid-atmosphere pressure anomalies valid 4/28. This data washes-out the PNW trough and replaces it with a small amount of high pressure ridging across the West.

Forecast Timing

Forecast radar/satellite valid 4/13-4/18.

Forecast Totals

4/13-4/15:

4/16-4/22:

A high wind event 4/3-4/4 deposited desert dust on Colorado’s snowpack. This seems to occur now every Spring. Dirty snow accelerates the melting of the snowpack by lowering albedo.

I co-authored a peer-reviewed article on Colorado’s Dirty Snowpack in 2010.

Below, MODIS visible satellite shows the brown tint to the snowpack in some places.

Dust aerosols on 4/3 were elevated over the desert southwest. The dominate flow in the upper atmosphere was from the southwest. That’s a perfect transfer conveyor-belt into Colorado on 4/3-4/4.

Vail’s live cam looking south clearly shows the brown/orange tint to the snowpack.

My forecast video 4/12:

Forecast Pattern

Forecast jet stream valid 4/21. Notice the large trough off the West Coast with support from the Northern Branch.

The Global Forecast System generates a larger, deeper trough. Forecast mid-atmosphere pressure anomalies on 4/20:

Looking even further down the road —> GEFS Forecast mid-atmosphere pressure anomalies:

This would mean a wet/cool forecast for the West Coast.

Forecast Totals

Tetons, WY:

4/12: 3″

4/13: 3″

4/14: 1″

4/18: 4″

4/20: 3″

4/12-4/14:

4/15-4/21:

Tomer’s Take: The storm track favors the PNW/BC/Northern Tier. One storm system drags a cold front with snow through UT, WY, CO, MT 4/12-4/14. Pattern shifts back to the PNW/BC through 4/20.

March 2023 Pattern

Looking back, March 2023 was a giant for Utah with record precipitation (dark green).

In Colorado, the trend is clear. The Western Slope received the most precipitation with less east. The Continental Divide truly divided.

Forecast Freezing Level

Wasatch:

4/11: 13100′

4/12: 12100′

4/13: 6400′

4/14: 7500′

4/15: 11000′

4/16: 11900′

Colorado Central Mountain Zone:

4/11: 14400′

4/12: 13600′

4/13: 12100′

4/14: 9000′

Forecast Pattern

Forecast jet stream valid 4/20. A trough of low pressure with rain/snow favors the PNW/BC/Northern Tier.

Forecast Timing

Forecast radar/satellite valid 4/11-4/16.

Forecast Totals

4/11-4/13:

4/14-4/20:

Tomer’s Take: The Western storm track continues shifting north favoring the PNW/BC/Northern Tier. The longer range jet stream is low velocity with high pressure ridging. Spring skiing inbound.

My forecast video 4/8:

Current Setup

Water vapor satellite shows an area of low pressure hitting the PNW/BC/Northern Tier. This is the dominate flow.

Forecast Pattern

Forecast jet stream valid 4/17. Notice the lack of a significant flow across the Intermountain West. It’s low velocity with plenty of high pressure ridging.

Forecast Timing

Forecast radar/satellite valid 4/8-4/13.

Tetons

4/12: 2″

4/13: 2″

Snowmass, CO

4/8: Late 1″ or less

4/13: 1″ or less

4/14: 1″ or less

4/16: 1″ or less

4/17: 1″ or less

Forecast Totals

4/8-4/10:

4/11-4/17:

4/8-4/17:

Snow chance is 4/16.