The rain will start very early Friday morning, be strongest between 5AM and 8AM and taper off through the evening and night.
Between 11PM Thursday night and 11PM Friday the models are predicting 60mm of rain to fall. Here is the breakdown:
11-2AM: 2 mm, 2-5AM: 8 mm, 5-8AM: 16 mm, 8-11AM: 16 mm, 11AM-2PM: 4 mm, 2-5PM: 4 mm, 5-8PM 4 mm, 8-11PM: 4 mm.
The good news is that it should clear away by Saturday morning and Saturday and most of Sunday looks dry.