The 22-year-old had returned home on Thursday night following the death of his father, Suranga Wellalage, earlier that day.
Wellalage was informed of the tragedy only after completing his first match of the tournament, the Group B fixture against Afghanistan in Abu Dhabi, where he bowled an expensive spell of 1 for 49.
Sri Lanka won by six wickets to book their place in the Super Four, after which Wellalage immediately flew back to Sri Lanka.
He is traveling back to the UAE with team manager Mahinda Halangode, who had accompanied him home.
Despite the personal loss, Sri Lanka Cricket confirmed he will be available for selection for the Super 4 schedules.
