Is It Really Going to Snow?

Yes.

At upper elevations.

But not a lot.

Don't plan on skiing.  

The instigator is a cold upper-level trough that is dropping into eastern Oregon and Nevada today.  By 0000 UTC 22 September (6 PM MDT Thursday afternoon), the low center and the coldest air over southeast Oregon.  

During the day today, we will be seeing some periods of rain as the weak front ahead of this system pushes through.  The temperature this morning (0700 MDT) is 34°F, with a wet-bulb temperature of 31°F, so that's cold enough for snow on the highest peaks of the Wasatch.  Snow levels will lower later this morning and probably get to around 9000 feet this afternoon.  

The GFS is putting out about 0.35 inches of water for Alta Collins through Friday night, which given relatively low snow-to-liquid ratios equates to about 3.5 inches of snow.  Those snow-to-liquid ratios are probably higher than they should be as this time of year the ground is warm and there will be melting between snow periods as temperatures rebound when there isn't precipitation.  

The HRRR is less excited, and putting out 0.17" of water and 1.4" of snow.  Yawn.  

If you want more, you'll have to hope that the strong showers (there may even be some thunderstorms) setup in the right place to provide a strong and prolonged period or two of snow.  That's not impossible, but it's more likely that we see 1-4" of wet snow above 9000 feet, with the higher accumulations happening only if we can sustain snowfall rates for a while.  

It would be better to save this until early November, but Mother Nature does what she wants.