The Hastings Rugby and Sports club player has made 15 first-class appearances for the Magpies since his 2012 debut. His father Rod played 18 games for the Bay before ending his first-class career in 1989.
"I know with the Super players away I could have started in all three of our first Ranfurly Shield defences [against Wairarapa Bush, Horowhenua-Kapiti and Mid Canterbury] but I have to look at the bigger picture," said Parsons, who will play for the Te Kawau club.
His final outing for his Hastings club before leaving the Bay will be in this weekend's 84th annual New Zealand Marist Spillane Cup tournament at Napier's Park Island. Hastings Rugby and Sports will be the only Bay club in the top division.
"I've been to two Spillane Cup tournaments and never won it. It would be good to win it before I leave the Bay," Parsons added.
Should hosts Napier Old Boys Marist win the Ham Cumming Cup second division they will gain promotion to the Spillane Cup division for next year. Napier Old Boys Marist and Hastings Rugby and Sports will also be represented in the colts section of the 16-team event.
Magpies head coach Craig Philpott, who has coached Parsons for the past five years, the latest three with the Magpies and two in Canterbury previously, said he was gutted to lose Parsons.
"Tom is a really good man who always gives 110 per cent when he takes the field. If I was his father or uncle and he came to me for advice I would have told him to take the Turbos offer ... he does need more time in the saddle if he's going to achieve Super Rugby honours and he isn't far behind our three locks who are already Super players."
Philpott said regular loosie Trent Boswell-Wakefield and Hurricanes under-20 rep Sanaila Waqa will be contenders for the fourth locking berth.
"I will also be hunting during the club season. I won't look out of the province for another lock ... our first shield defence will be a massive carrot for a player in the Bay's club competition," Philpott said.
While Parsons is on the move, former Wellington loosehead prop Tolu Fahamokioa will arrive in the Bay next week to start a two-year contract. Fahamokioa, 23, played 10 games for the Lions last year, nine as a starter, and was in the Hurricanes squad as injury cover earlier this year.
"We're really excited Tolu has decided to come to the Bay to add depth to our propping ranks and also enhance his chances of playing Super Rugby," Hawke's Bay Rugby Union CEO Mike Bishop said.
"He was one of the better forwards in the Lions team when they challenged us for the shield last year," he added.
A former Tawa club player, Fahamokioa has yet to be allocated a Bay club or job in the Bay.
A Tongan, Fahamokioa has lived in New Zealand since 1999. He was studying to be a nurse before deciding to give rugby a serious crack last year.
