Umbrellas are prohibited at Michigan Stadium, but ponchos and raincoats are allowed. There is a 40 percent chance of thunderstorms for spring commencement.

File photo: Lon Horwedel | AnnArbor.com

All eyes are on Saturday's weather forecast. And so far, it's looking a little dicey.

More than 80,000 people are expected to watch President Barack Obama's commencement speech at Michigan Stadium on Saturday. And they may be doing it in the rain. Or even worse, thunderstorms.

But at least it will be warm.

University of Michigan weather observer Dennis Kahlbaum said there's a 40 percent chance of thunderstorms in Ann Arbor that day.

Nonetheless, Michigan Stadium's longstanding ban on umbrellas still applies to Saturday's commencement. Ponchos and raincoats, though, are allowed inside Michigan Stadium.

Despite the chance of rain, Saturday should be a warm day, reaching the 60s by noon and 76 degrees by 2 p.m., Kahlbaum said. 

The gates of Michigan Stadium will open at 6:30 a.m. At that time, graduates will gather on Elbel Field for continental breakfast, security instructions, and to tape short video messages. Seating is general admission - first come, first served.

There is no Plan B venue if thunderstorms arrive. "Given the size of spring commencement," U-M explains on its commencement instructions website, "it is not logistically feasible to move this ceremony to an indoor location and still maintain its university-wide, inclusive focus."

If weather reaches inclement levels, the ceremony could be shortened, and pre-recorded music might replace the commencement band, U-M said.

James David Dickson can be reached at JamesDickson@AnnArbor.com.