Townsend will announce the enlarged pool of players at the squad’s Oriam training base at Edinburgh Heriot-Watt University campus 138 days before the Scots open their Pool A campaign against Ireland in Yokohama on 22 September.
Four years ago Vern Cotter named 46 players ahead of preparation for the tournament in England and it is expected Townsend will pick roughly the same before whittling it down to the 31 who will make the ‘plane later in the year.
The national coach will have the opportunity to provide injury updates on the likes of Saracens centre Duncan Taylor, whose season has been wiped out after damaging anterior and posterior cruciate ligaments, and current skipper Stuart McInally, who left the recent Glasgow-Edinburgh game with an ankle problem.
There is expected to be a return to the Scotland squad for experienced lock Richie Gray, who has recovered from a lengthy back injury to bank an impressive run of games for European semi-finalists and French league leaders.
Young Glasgow second-row Scott Cummings should also get a chance to stake a claim in one of the most competitive positions.
Scarlets flanker Blade Thomson has also made a comeback from the concussion he suffered playing against Edinburgh back in early November.
Close to a full XV of those named will not make it to Japan but, with the season still to complet - notably for Glasgow in the Pro14 play-offs - a summer of twists and turns lies in store as Scotland face four warm-up games against France and Georgia, meeting both nations home and away.
The first hit-out will be away to the French in Nice on Saturday August 17 before a return match at BT Murrayfield the following week. Then comes a historic first Test away to Georgia in Tbilisi on August 31 before hosting the east Europeans in Edinburgh on the first weekend of September.
As well as Ireland, Scotland will face Samoa, Russia and hosts Japan in Pool A as they seek to repeat their 2015 feat of reaching the knock-out stages, when they famously lost 35-34 to Australia at Twickenham in a quarter-final classic.