Graupel is Good

 The storm delivered as forecast (I love to say that!) in most areas including 11 inches through 8 AM at Alta-Collins.  

Here at the University of Utah, the ground was sprinkled this morning with some beautiful graupel particles.  Below is an example of a pea sized, conical-shaped graupel particle outside the Student Life Center. 

Graupel forms as tiny supercooled cloud droplets collide and freeze on an ice particle.  Typically it has a higher fall speed than snowflakes (3 meters per second compared to 0.5 to 1 meter per seconds) and requires a fairly strong updraft to form.  Radar imagery overnight suggests that the convective cell moving over the University of Utah at 12:40 UTC (6:40 AM, see below) may have produced it, although there were one or two other cells that moved through the area earlier.  

We are now solidly into the unstable, postfrontal flow, although as shown in the time-height section below, the flow direction below and at crest level is predominantly westerly to west-northwesterly and perhaps not quite optimal for Little Cottonwood.  

Nevertheless, periods of snow will predominate today and, given the April sun, we will probably see some strong snow showers this afternoon, possibly with thunder and lightning.  Expect to seem some graupel or pea-sized hail as well.  My best guess is 3-6" more for Alta Collins, although the hit-and-miss nature of what we will see later means there's a wide range of possibilities.  A direct hit by a strong cell would really add up, for example.