Smithies, 25, has played no part in Huddersfield’s last two games after the club accepted an offer, believed to be for £1.5 million, from their Championship rivals.
“Well I think it’s almost done now,” Powell told a press conference on Thursday ahead of his side’s league game at Fulham this weekend.
“Obviously there’s been a bit of a hold-up but I think that was more to do with QPR and their medical side and the availability of their medical consultant.
“I’m led to believe that’s why it hasn’t been done in the last two or three days so I think it will be all signed and sealed later (on Thursday).
“It’s a real shame because local lads that come through at their local club is always a great story for everyone.”
Smithies made over 250 first-team appearances for Huddersfield since progressing through the club’s academy to make his debut as a 17-year-old in December 2007.
He scored the winning penalty in Town’s League One play-off penalty shootout win against Sheffield United at Wembley in 2012.
Powell added: “He’s left a mark at this club with regards to not only his development as a footballer, goalkeeper and as a man but when you think of the story of the play-off final, the local boy who scored the penalty to get the club promoted to the Championship.
“Since I’ve been here he’s been excellent. He’s earned us points, he’s made some great saves and I think he’s developed.
“But it’s the life of a footballer and I really wish him well, he’s a top footballer.
“But he moves on and we move on and from me, and on behalf of all my staff, we all wish him really well.”
Powell said he was happy to promote Joe Murphy to his number one goalkeeper and also confirmed the club had turned down three bids from an unnamed club for midfielder Jacob Butterfield.
Butterfield was linked with Derby last week, but Powell insists the club will not be selling one of their best players.