Snowmelt increase over weekend

In my blog on Friday, I gave a comprehensive review of the current status of snowmelt and runoff in the upper Henry’s Fork watershed. Despite cooler daytime temperature highs over the weekend, warmer nighttime lows and rain contributed to accelerated snowmelt between Friday and Monday. Both the Crab Creek and Island Park SnoTel sites report large decreases in Snow Water Equivalent (SWE) over the last few days, with both locations losing about 2 inches. Weekend weather left Crab Creek with 2.4 inches of SWE and Island Park with 1.6 inches. Crab Creek now has 17.9% of its peak water-year SWE left and Island Park has 11.4%, meaning each site has lost about 80% and 90% of its total water-year SWE respectively. With runoff in full swing when 50% of peak water-year SWE has melted, Crab Creek and Island Park have almost exhausted their snowpack and contribution to runoff. We expect streamflow between Henrys Lake and Island Park Dam to begin decreasing as a result. Note that runoff this year is happening about two to three weeks earlier than what we have normally experienced over the last thirty years.