Worcestershire Seconds came off second best on the opening day of the four-day encounter with their Warwickshire counterparts at Coventry and North Warwicks CC.
The Seconds elected to bat and were dismissed for 59 – their lowest total of the campaign.
Warwickshire then replied with 182-2 from 57 overs by the close with Pat Brown and George Brown collecting one wicket apiece.
When Worcestershire batted, George Rhodes (10) was caught at mid wicket off the bowling of England Under-19 paceman Henry Brookes with 17 on the board.
Ollie Westbury (3) was caught behind of Chris Wright but it was Thornton who did most of the damage in the morning session as the ball nibbled around under cloudy skies.
Alex Hepburn and Ross Whiteley were both bowled for nought in the space of three balls.
It became 40-5 when Tom Fell, having battled for 13 off 42 balls, became the third player to be bowled by Thornton who with his next delivery had Alex Milton (0) caught behind.
Jack Shantry survived the hat-trick ball as Worcestershire lunched at 40-6 off 27 overs and Thornton had figures of 7-3-13-4.
Brookes returned to the attack after the interval and Shantry (7) was caught and bowled.
Brown (2) fell to Keith Barker and then Ben Twohig, after holding out for 80 minutes and 51 balls, was lbw to Brookes for 10.
Barker wrapped up the innings by bowling Scrimshaw (1).
Warwickshire openers Andrew Umeed and Liam Banks put on 109 before the former was bowled by Brown for 43.
Former England batsman Jonathan Trott (20 not out) then had a let off at second slip before he had scored.
But Scrimshaw did eventually make a second breakthrough in bowling Banks for 85.
WORCESTERSHIRE SECONDS – first innings
Rhodes c Thornton b Brookes 10
Westbury c Mellor b Wright 3
Fell b Thornton 13
Hepburn b Thornton 0
Whiteley b Thornton 0
Twohig lbw Brookes 10
Milton c Mellor b Thornton 0
Shantry c and b Brookes 7
Brown c Singh b barker2
Morris not out 2
Scrimshaw b Barker 1
Total (all out) 59 in 36.5 overs
FOW: 17, 21, 23, 23, 40, 40, 51, 56, 56 59
WARWICKSHIRE SECONDS – first innings
Umeed b Brown 43
Banks b Scrimshaw 85
Trott not out 20
Lamb not out 20
Total (for 2 wickets) 182
FOW: 109, 140