Major disruption can be expected at hospitals and health care facilities across the Trust throughout tomorrow as health workers embark on a 24-hour strike.
The minor injuries unit at South Tyrone Hospital in Dungannon will be closed all day Wednesday, reopening at 9am Thursday.
And, while the emergency departments at Craigavon and Daisy Hill in Newry will remain open, they are expected to be even busier than usual.
The Trust says it will prioritise the most urgent patients.
The 24-hour stoppage is the latest in the campaign by nurses and other health care workers for better pay and improved conditions in which to treat patients to a standard of care which they feel the public deserve.
The strike, however, will lead to significant upheaval in the service locally.
Seventy-five people have had planned in-patient and day-case surgery postponed.
A total of four planned operations have been cancelled.
Emergency surgery is going ahead.
All community mental health services at Trasna House in Lurgan will be closed all day on Wednesday. Anyone who requires urgent care should contact their GP who will have access to emergency and urgent mental health services.
All day centres and resource centres – 21 in total – will be closed. These are Lisanally, Keady, Clogher, Edenderry, Orchard, Meadows, Donard, Crozier, Windsor Day Centre, Newry; Laurels Day Centre, Newry; Binnian Day Centre, Kilkeel; Millview Day Centre, Bessbrook; Crossmaglen Day Centre; Aughnacloy (McCague) Centre; Gortgonis Centre Coalisland; Appleby Day Centre, Armagh; Oakridge Day Centre, Dungannon; Station Road Day Centre, Armagh; Linenbridge Day Centre, Banbridge; Bannvale Day Centre, Gilford; Manor Day Centre, Lurgan
All those patients affected have been notified, says the Trust.
Community-based clinics and services will also be affected, with 172 appointments having been cancelled. Again, patients have been notified.
The district nursing service will be limited in all areas to essential calls only, and domiciliary Care will only be provided to the most dependent service users. Clients have been advised.
There will be no canteen or coffee bar facilities available in the Trust and only patient meals will be provided.
A spokesperson for the Southern Trust said: “We will do everything possible to keep services running, but in many areas we will be working with significantly reduced staffing.
“This includes a reduced service on our switchboards which may lead to delays answering calls.
“We apologise for any inconvenience this may cause.”