After Atlanta (8-9) jumped to a 9-2 lead, the Storm scored 14 of the next 15 points and never again trailed. Stewart converted a four-point play and then hit a jumper to spark a 14-0 run that made it 50-21 with a minute left in the first half.
The Dream outscored Seattle 29-19 in the third quarter and a 3-pointer by Tiffany Hayes trimmed their deficit to 72-66 early in the fourth, but Atlanta got no closer. Loyd answered with a 3 and then a pull-up jumper to push the lead back into double figures.
Angel McCoughtry scored 26 points and Hayes added 23 for the Dream.
Seattle shot 51.4 percent from the field, including 9 of 20 from 3-point range.