The encounter was played in front of a minimal crowd despite free admission, since it clashed with a 10km race and half-marathon in Worcester, while heavy rain was forecast for much of the day.
In cool and overcast conditions, with a green wicket and an early start, Glamorgan did well to get the 50 up inside the powerplay through Parfitt and Freeborn, with captain Parfitt finding the gaps well as she hit five boundaries.
She top-edged Hannah Rainey through to wicketkeeper Winfield-Hill to signal the start of Glamorgan’s struggles, which saw Emily Burke loft Olivia Thomas to deep mid-wicket while Bethan Ellis was run out for six.
Bethan Gammon’s 21 off 16 provided Glamorgan with some momentum but Freeborn (41 off 50) could not keep up her earlier rate, and Olivia Thomas bowled both in the 17th over as the 20-year-old justified her pro contract announced a few days previously.
Bea Ellis and Gemma Porter took the target to more than a run a ball, but as the players cast anxious eyes to the skies, Yorkshire looked favourites at halfway.
That impression was confirmed as Yorkshire took 10 off the first over and continued at the same rate.
Winfield-Hill, with 104 England appearances to her credit, rattled off her half-century in just 27 balls and Yorkshire had 113 on the board in 10 overs.
Erin Thomas, an England Under-19 player, accelerated to match her captain with three powerful sixes.
The scores were level when Winfield-Hill was caught at mid-on off Porter after striking 12 fours, to give Glamorgan a token scrap of consolation, but it had been a one-sided affair since the Welsh side’s powerplay at the start.
The decision to play a T20 was vindicated by heavy rain arriving around 20 minutes after the match ended.
Yorkshire were deserved winners despite only finishing fourth in the group stage after being without their Hundred players for several weeks, having also dispatched table-topping Middlesex.
Glamorgan, who were losing semi-finalists to Yorkshire in the Blast, could reflect on mostly consistent performances in their first season as a women’s county team.
Yorkshire’s player of the match Olivia Thomas told BBC Sport West Yorkshire:
“I’m absolutely buzzing, it’s wet and cold and not ideal for leg-spinning, but I tried to keep the ball dry, bowl full and straight and keep the stumps in play and it worked.
“As a team we did well to stay calm [at the start], we always back ourselves to pull things back.
“It’s amazing, I can’t tell you how much it means to pick up a trophy after coming in with a new start to sign my first professional deal. Next thing you know you’re picking up a trophy.
“We came away absolutely gutted from [losing] the T20 final and we’ve been able to use that to push us forward in the second block of 50-over games.
“It’ll be a good challenge in League One, the next step forward. We beat Essex in the cup so we’re more than ready for it.”
Glamorgan captain Lauren Parfitt told BBC Sport Wales:
“It was really difficult, we thought we were just short of where we needed to be with the bat, then they came out and batted really well so credit to them.
“We’re really proud to have got to the final, it was unexpected that we were going to play 20 overs until this morning. The girls handled that well and we’ll look to next season and beyond.”
