Sue Bird added 14 points, five assists and four rebounds for the Storm (5-7).
Crystal Langhorne led Washington (2-8) with 21 points. Matee Ajavon added 11, and Noelle Quinn had 10.
Seattle never trailed again after Bird hit a free throw to put the Storm up 10-9 with 4:35 remaining in the first quarter. Bird threw a no-look pass in the fourth quarter that a rolling Ewelina Kobryn put in while being fouled. Kobryn's made free throw put the Storm in front 64-46 and ended doubt about the result.
Bird hit a jumper to close the third quarter and push Seattle in front 52-37. The Mystics' 17 third-quarter points almost matched their 20-point output in the first half. But, it still wasn't enough to get back into the game.
Seattle led 31-20 at the half after an efficient second quarter during which it shot 54.5 percent. Washington's 20 points were the fewest Seattle allowed in a half this season. The Mystics scored just nine points in the second period, shooting 4 for 19 from the field. The Storm played zone for a portion of the quarter, which forced the Mystics' offense to become stagnant. Washington shot several deep jump shots with little time remaining on the shot clock.
A 3-pointer from Bird and a layup by Camille Little pushed the Storm in front 28-18 in the second quarter, forcing a Washington timeout.
Seattle called a timeout with 6:17 left in the first quarter to discuss the dysfunction that led to an early 7-2 lead for the Mystics. A 13-2 Storm run followed. Wauters hit a jumper, Little drove and scored, and Bird hit a 3-pointer. The blitz continued when Tina Thompson scored in the lane and rookie Shekinna Stricklen hit a jumper.
Washington stopped the onslaught with a jumper from Lindsay Wisdom-Hylton.
Seattle led 15-11 at the end of the first quarter.
Former Storm player Ashley Robinson returned to Seattle for the first time since being traded to Washington in the offseason. Robinson received a nice ovation when she checked in with 6:45 remaining in the second quarter and scored two points in just four minutes on the floor.