Former England wicket-keeper Sarah Taylor was left concussed as the inaugural Charlotte Edwards Cup began.
Taylor, who came out of retirement this month, could not bat for Northern Diamonds after being hit while keeping late in the Thunder innings.
Thunder edged the game by 12 runs, while Sunrisers beat Western Storm and Southern Vipers routed Central Sparks.
Earlier, South East Stars eased to a six-wicket win over Lightning in the T20 competition curtain-raiser.
English cricket’s new regional competition has been named in honour of Edwards, who guided England to two World Cup wins in 2009.
Bethany Harmer hit the only six of the Lightning innings in a 25-ball knock of 34, but only Abigail Freeborn provided any support as the hosts were bowled out for 107 in 19.1 overs.
Stars captain Bryony Smith got the chase off to a positive start, hitting 30 off 14 balls, including two maximums, before Phoebe Franklin (24 not out) took the visitors home in comfort with 6.5 overs to spare.
Thunder opener Emma Lamb hit 58 from 43 balls and Natalie Brown made 25 to help the hosts make 118-6 at Headingley.
And the England all-rounder then starred with the ball, taking 4-13 and running out Helen Runby as Diamonds were restricted to 106-9 in reply despite 32 from Sterre Kalis.
Sunrisers cruised past Western Storm with a stylish seven-wicket win at Taunton.
An unbeaten 36 off 24 balls from Natasha Wraith, and 31 from skipper Sophie Luff helped the hosts recover from 51-5 to post 129-6.
But England T20 international Mady Villiers (36 off 26 balls) and Grace Scrivens (35 not out) eased the Sunrisers to their target with seven wickets and 17 balls to spare.
Charlie Dean took 5-19 as Southern Vipers skittled Central Sparks for 83 at Edgbaston, a total littered with five ducks and underpinned by Marie Kelly’s 36.
Vipers lost captain Georgia Adams in the first over of their chase, but England star Danni Wyatt, left out of the ODI squad to face India, hit a rapid 45 from 33 balls and Maia Bouchier made an unbeaten 25 as the visitors chalked up a commanding eight-wicket win with 6.5 overs to spare.
