judging by the NWS forecast for the feather river below the dam at Gridley, it appears they plan to open the main spillway midday tomorrow to at least 50,000 cfs
#OrovilleSpillway press briefing tomorrow at 9 am. Watch via DWR Facebook live. http://www.facebook.com/CADWR/
source: https://twitter.com/CA_DWR/status/842468925384269824