Another Shot at 900

Alta is now closed for the season, but the race to 900 continues.  

Snowfall since Oct 1 now sits at 894".  Tantalizingly close.  I hear rumors that Alta Ski Patrol sits at the ready to verify 900 when we get there.  These are, however, only rumors.  

It appears we have one storm to get there before the end of the month, and that's from today through tomorrow as a closed low moves through northern Utah.  Below is the GFS forecast valid 0900 UTC 25 April (3 AM Tuesday) when the 500-mb low is forecast to be right over Salt Lake City.  

With cold air aloft, this looks like a spring special.  Lots of convection with periods of mountain snow through tomorrow, possibly with thunder and lightning.  Storms will be hit or miss.  The GFS tries to get one last gasp of northwesterly flow going and the HRRR even generates a lake band Tuesday morning although it's centered over the Salt Lake Valley rather than the central Wasatch.

However, the models are all over the place on this one.  If you are praying for snow and the record to fall, you'll like the 6Z GFS, which puts out 1.22" of water and 16" of snow by 2 PM Tuesday.  Faceshots!

On the other hand, the 6Z HRRR is the Debbie Downer of this forecast suite, giving Alta nearly a Nothing burger with only 0.12" of water and 1.2" of snow.  Pathetic.  

A big reason for this difference is the HRRR keeps the precip to our north with Alta dry until 6 AM Tuesday.  Only then does it generate the lake band (mainly west of Alta over the Salt Lake Valley) and some precipitation.  In contrast, through 6 AM Tuesday, the GFS generates an incredible 1.1" of water and 15" of snow.  For meteorologists, that's a Pepto Bismol forecast if ever there was one. 

To drive that point home a bit further, the downscaled SREF also has a range from near nothin' to over 1.5" of water and 0 to 25" of snow.  The snow-to-liquid ratios its anticipating are probably too high, but even accounting for that gives a range of 0 to 18".  

I'm inclined to go with 0.5 to 1.0 inches of water and 5-10 inches of snow.  This is basically the middle of the distribution and I confess it's a low probability forecast.  That said, I don't think a total shutout is going to happen with such a deep, cold trough moving overhead.  

Odds of getting 6" and breaking 900: 80%.

Place your bets.  For those of you who thought 900 would happen last week, now is your opportunity to do double or nothing.