Southern Vipers 191 for 6 (Wyatt 76, Bouchier 56) beat Thunder 173 for 8 (Morris 36, Adams 2-26) by 18 runs
Danni Wyatt and Maia Bouchier smashed explosive fifties to set the foundations for Southern Vipers to beat Thunder and reach the Charlotte Edwards Cup final. England duo Wyatt and Bouchier shared a 108-run stand for the first wicket with scores of 76 and 56 respectively as Vipers chalked up 191 for 6 - despite Olivia Bell's career-best 4 for 36.
Although there were good contributions from Fi Morris, Deandra Dottin, Ellie Threlkeld, and Sophie Ecclestone, Thunder ended up 18 runs short on their Finals Day debut. Vipers will play the Blaze, who were unbeaten in the group stage, in the final at 4pm.
The tone for a run-filled afternoon at New Road was set when Bouchier cut her first ball to the boundary after Thunder had stuck Vipers in to bat first. The first 11 overs were a masterclass of attractive power striking from Bouchier and Wyatt, the former preferring to go down the ground and the latter using her trademark cut plentifully.
Both were released by England for this match, having spent time preparing for the upcoming Women's Ashes Test, and proved why they are in the reckoning for the series against Australia. Their 108-run stand was Vipers' highest partnership of the competition, as Bouchier won the race to a half-century. She got there in 29 balls to Wyatt's 34, in the same over.
Bouchier fell for her Charlotte Edwards Cup best of 56 - which included 10 fours - after a leading edge was caught by keeper Threlkeld after five seconds of hang time.
Wyatt was unperturbed by the wicket as she pinged international team-mate Ecclestone for the only six of the innings - left-arm spinner Ecclestone would eventually return an uncharacteristically expensive 1 for 50.
Vipers lost six wickets during the latter stages but maintained their run rate to reach 191 - their highest T20 score and the fourth-highest in the competition's history.
Those wickets were almost exclusively down to Bell - who had Georgia Adams caught at point, Wyatt crashing a huge full toss to deep midwicket, Freya Kemp bowled and Ella McCaughan stumped. The offspinner took two wickets in successive overs and boasts a scarcely believable tournament strike rate of 6.63 with her 11 wickets coming in just 12 overs.
Thunder matched Vipers in the powerplay - both teams rocketed to 50 - thanks mostly to Morris' six sweetly-struck boundaries. But they did lose Emma Lamb third ball when ramping Anya Shrubsole and Liberty Heap, bowled by Linsey Smith.
Morris had come into the match on the back of scores of 36, 44 and 42 not out in her previous three innings - with Thunder winning four of their last five matches to reach Finals Day. She contributed with 36 before Georgia Elwiss plucked a stunning one-handed catch at full stretch.
Former West Indies powerhouse Deandra Dottin needed only four balls before swishing a six over the leg side and continued with an array of attacking strikes in a 14-ball 24 before her aerial bombardment was ended by a catch at long-on.
Ecclestone and Threlkeld put on a productive 42 before the former was caught three balls after being dropped for 33. Naomi Dattani skewed to point and the 25 needed off the final over was easily defended by Adams - as she picked up the wickets of Threlkeld and Danielle Collins for good measure.