“Upcoming snow in the PNW should amount to very heavy amounts,” says reader H.B. Schmidt.
“It’s amazing how much water these storms put out in the form of snow and ice. The Weather Channel shows large areas across Washington, Oregon, and Idaho that will get well over two feet (60 cm) of snow between now and next weekend.
“No wonder these states are excited about building a snowpack to refill their reservoirs. A few events like this over the course of a long winter, and suddenly all that snow provides much more than a pretty backdrop for photo opportunities,” says H.B.
“Rough estimates of the area that will get 2+ feet of snow:
165 miles x 475 miles = 78,375 sq miles
“At a snow water equivalent average across all of that at the standard 10:1 inches, that would be 2.5 inches snow water equivalent (SWE): 24 ÷ 10 = 2.5 inches, or 0.2083 feet
1 sq mile = 5,280 feet x 5,280 feet = 27,878,400 sq ft
27,878,400 sq ft x 78,375 sq miles x 0.2083 ft SWE = 455,202,000,000 cubic feet SWE
“There are 43,560 cubic feet per acre-foot of water, so 455,202,000,000 ÷ 43560 = 10,450,000 acre-feet of potential water run-off from this ONE event.”