A pretty good guess for the rate of snowmelt in a mature snowpack on north facing aspects in the Wasatch Mountains in late spring and early summer is 2–2.5 inches a day. Obviously this changes depending on the weather and snow conditions (for instance, how dusty and dirty it is) but it works pretty well in patterns like these and is a pretty good guess for the rate of snow loss this time of year.
The gradual demise of the snowpack at Alta-Collins can be seen in the 7-day trace of hourly snow depth measurements below.
The drop over this 7 day period is from 115 to 98 inches, or an average of 2.4 inches per day. At that rate, we have 41 days until the end of snow at this site, which would be about June 27th.