Skinny Skiing followed by the Storm Forecast

Hoping to get in one last hour of cross-country skiing this winter, I drove up to Soldier Hollow this morning and took advantage of the man-made ribbon of white that still covers about 10 km of trails.

Conditions were surprisingly good.  The 10 K of trails that were open were well covered and meticulously groomed.  With few people out, it made for fun skiing.  Trail passes were $10, so the price was also right.

By now, you are well aware of the forecast of a storm beginning tonight.  Although we may see a few mountain snow showers today, things don't really pick up until sometime between 9 PM and midnight tonight as an upper-level short-wave trough moves through.  Snow levels through midnight will reach 7000-8000 feet, before falling late tonight.  In the wake of the trough, strong northwesterly flow should yield periods of snow showers through Monday.

For Alta-Collins, most of last night's NCAR ensemble members are going for 0.6 to 1.2 inches of water through 0000 UTC 15 March (6 PM MDT tomorrow).

The NAM is a bit more excited, going for 1.36".  The NAM time-height shows the overnight trough passage and then persistent westerly, potentially unstable flow through tomorrow (and into the overnight period.

There are a couple of concerns that I have about this event.  First, the flow as currently forecast never comes all the way around to northwesterly through tomorrow afternoon, which could limit accumulations in upper Little Cottonwood.  Second, there is always a lot of uncertainty concerning how productive the post-frontal instability showers will be in the Wasatch.

For these reasons, I'm issuing a forecast that is a bit more pessimistic than most you will see.  For 6 PM tonight through 6 PM tomorrow (Monday) I'm going for .7 to 1.4" of water and 7-14 inches of snow at Alta-Collins.  That relatively low 10 to 1 snow-to-liquid ratio reflects concerns about high density snow due to the warmth of the storm overnight and the strong wind tomorrow.  Ultimately, the snow amounts will depend a great deal on what falls tomorrow, when the snow density should be lower.  The NWS is going for 10-20", which I can see verifying if things go bigger tomorrow.

Bottom line: Snow is coming, but keep your expectations tempered.  It's always better to be surprised with too much than too little.