Scorchers thrash Thunder in WBBL semifinal

The Perth Scorchers have qualified for the WBBL title decider after thrashing the Sydney Thunder by 27 runs in Thursday's semi-final showdown at Optus Stadium.

Chasing 149 for victory, the Thunder crashed to 5-46 in the 11th over before limping to 8-121 from their 20 overs.

Spinner Emma King (3-17 from four overs) starred with the ball to help bury the Thunder.

The Scorchers will now play either the Sydney Sixers or Adelaide Strikers in Sunday's final.

Perth lost last season's final to the Sixers, but they now have the chance to erase those painful memories.

"It's a bit of deja vu for us. Hopefully we can go one better," King said.

"It spurred us on for pre-season. We're really excited to take on the challenge. We've just got to stay calm under pressure."

The Thunder were warm favourites to beat the Scorchers in the semi-final after finishing the season in second spot.

But the third-placed Scorchers were controversially gifted home-ground advantage because the match was being played as a curtain raiser to the men's BBL semi-final.

Englishwoman Fran Wilson, who top scored for the Thunder with 46 off 28 balls, said the loss of home-ground advantage couldn't be blamed for the loss.

She predicts big things for the Thunder in the future, and hopes to be back for next season.

"I think they're a really special group, who in future years will definitely go on to win the Big Bash again," Wilson said.

Scorchers openers Elyse Villani (38 off 37) and Nicole Bolton (37 off 26) combined for a 65-run opening stand to help set up the Scorchers' innings.

Natalie Sciver (38 off 28) and Heather Graham (27 off 29) kept the momentum going to lift the Scorchers to a formidable 2-148.

Villani (519) became just the fourth player to score more than 500 runs in a WBBL season.

The Thunder's victory hopes were all but over after slumping to 3-35 in the eighth over.