VIDEO : Why Was Julian Gone From 'The Flash'?

The Flash's fourth season is officially here, and fans get an explanation for Julian's absence from Team Flash early on.
Mild spoilers for The Flash's season four premiere, 'The Flash Reborn', below.
Early in tonight's episode, Joe (Jesse L. Martin) tells Iris (Candice Patton) that they've been short staffed at the crime lab "ever since Julian moved back to London" with the implication that with Barry's absence getting harder to explain they are going to have to replace Barry.