Pass variable apex to flow from trigger

trigger deleteServiceLine on Service_Line__c (before delete) {
//to store the id of the record that triggered the flow
String varServiceLineID;
if (Trigger.isDelete) {
     //grabs id of the record and stores it in a variable for later use. 
      varServiceLineID = Trigger.Old[0].Id;
     //displays the value that is stored in the variable
	System.debug('this is the ID I am fetching is: ' + varServiceLineID);
  }
}