The duo were listed as being out "indefinitely" last week but look to be on track for a prompt return.
Harris is the squad's most valuable player, along with captain Roger Tuivasa-Sheck. He brings an unmatched work rate and presence in the middle, both defensively and on attack.
Townsend brings much needed experience to the spine and no one else in the current squad can rival his ability as an organiser and playmaker. He made an instant impact in the Dragons clash, despite the result, and could be a point of difference in the Warriors' run home.
In other squad news Euan Aitken and Josh Curran could come straight out of isolation and back onto the field for the 18th-round clash.
They've been included in the extended 21-man squad despite spending two weeks cooped up in their apartments after being required to isolate in line with the NRL's Covid-19 protocols.
The duo joined their teammates for a recovery session on Monday and the squad's last field session at the Tuggerah Sports Complex before they leave the Central Coast on Wednesday.
Coach Nathan Brown has named Curran on the interchange with Aitken listed in the reserves.
It's the same starting line-up as the one used against the Sharks last Sunday while Curran and Kane Evans are listed in the 17 replacing Jack Murchie and Ben Murdoch-Masila.
Penrith have only lost twice this season and are second on points difference behind Melbourne on the NRL ladder.
The Panthers will be without injured Origin stars Nathan Cleary and Jarome Luai in the halves while they also have winger Brian To'o, loose forward Isaah Yeo, hooker Apisai Koroisau and back rower Liam Martin lining up for New South Wales in Wednesday's final State of Origin match.
Warriors v Penrith Panthers
6.00pm, Sunday, July 18
Venue TBC
1 Reece Walsh
2 Dallin Watene-Zelezniak
3 Rocco Berry
4 Marcelo Montoya
5 Roger Tuivasa-Sheck (c)
6 Kodi Nikorima
7 Sean O'Sullivan
8 Addin Fonua-Blake
9 Wayde Egan
10 Matt Lodge
11 Eliesa Katoa
12 Bayley Sironen
13 Jazz Tevaga
Interchange:
14 Josh Curran
15 Leeson Ah Mau
16 Bunty Afoa
17 Kane Evans
18 Adam Pompey
20 Euan Aitken
21 Chad Townsend
22 Tohu Harris