“We had to win today,” Blackwell said. “I thought the Stars did a great job keeping the pressure on in their run chase.
“We’re still alive in this competition, but things need to go our way with other teams this weekend. We’ll just control what we can.”
In reply, the dangerous Lizelle Lee was adjudged lbw for a duck before Mignon du Preez (55) and skipper Elyse Villani (43) kept the Stars in the hunt with a breezy 78-run stand for the second wicket.
Villani succumbed to a fine catch from player-of-the-match Blackwell before du Preez was stumped off spinner Sam Betts two overs later to shift momentum to the Thunder.
Erin Osborne rattled off an unbeaten 27 towards the end, but with the experienced Rene Farrell (2-28) and Hannah Darlington (1-26) bowling smartly at the death, the Stars slipped off the pace.
The Thunder (5-7-1) need a lot to go their way to leapfrog the fourth-placed Sydney Sixers (6-5) and fifth-ranked Melbourne Renegades (6-6) into the top four, but mathematically they have a chance.
They must beat the Renegades at St Kilda on Sunday and hope the Sixers lose their Hurstville Oval double-header against the high-flying Adelaide Strikers.