The bus replacements for the forthcoming weekend, 17/18 May and several subsequent weekends (but not the bank holiday weekend). Stopping trains will be running between Manchester (but via Victoria not Piccadilly direct) and Huddersfield. Bus replacement east of Huddersfield towards Dewsbury/Leeds/Wakefield but the trains to Bradford via Halifax will be running. Timings will be different from usual. Please check before travelling using https://www.nationalrail.co.uk/, https://www.tpexpress.co.uk or whatever app or website you usually rely on.
There is also a new timetable effective from 18th May until 27th September, which appears to show little change from the existing timetable up to 17th May. It does not show the changes from 30th August until 28th September, which is when Huddersfield station will be shut along with the entire route as far as Stalybridge. For that period of 30 days, it will be the dreaded Rail Replacement Bus Service. Link to new timetable is at https://www.tpexpress.co.uk/travel-updates/timetables.