A lot has happened in Cleveland since the last time the lovers of Green and Guinness assembled downtown.

We've hosted the world with the RNC, and we've held the largest parade in city history after the Cavaliers won the NBA Championship.

So, this year: New equipment, new ideas and new things you need to know before coming downtown.

9,000 to 10,000 will be marching. A quarter million watching.

And a small army of police patrolling, aggressively.

"Our vigilance is going to be heightened," says Cleveland Police Commander Harold Pretel. "Part of that vigilance is going to be, things that can do us harm."

The parade starts at 1:04 p.m. Friday on East 18th and Superior running to -- and unlike last year -- thru Public Square, before ending at Mall A.

While attendees' wardrobe along the route will share a common color, police hope your observational skills Friday are not green, but well-honed.

"See something, say something, do something, " says Pretel. "That do something could be take a picture, make a note of a license plate or an individual or direction of travel."

There's no single threat triggering the extra alert, but lessons learned from massive downtown crowds over the last 12 months are at play.

Whether it was when we were decked out in Wine and Gold. Or full of red, white and blue.

But if the radar is blue, or the winds blow like they have in recent days...the Irish, known for their luck -- may run out of it.

City officials say if the weather is rough, they may postpone the parade. If that happens, the decision could come as early as Thursday evening or as late as 6 a.m. on Friday morning.

Two other notes to remember come parade time: Backpacks taken along the parade route are subject to inspection. And in case people get lost, 'The Family Unification Center' will be the at the Justice Center downtown.