KeyArena meeting traffic has backed up northbound I-5 and West Seattle outbound commuters before, so we’re sharing this SDOT alert:

Tomorrow, Thursday, September 13, a crowd of 15,000 is expected to attend the Microsoft Annual Company Meeting at the Key Arena. The meeting is scheduled to run from 10 a.m. to 3:30 p.m. Attendees will begin arriving at the Seattle Center in 200 buses and some 4,000 private vehicles as early as 8:30 a.m. Motorists should expect heavy congestion in the morning between the I-5 Mercer off-ramp and the Seattle Center and on streets surrounding the Center. The beginning of the afternoon commute could well be impacted in the same area as attendees will be leaving the meeting at approximately 3:30 p.m. Drivers should plan ahead for possible delays.