President Obama is in town to raise money for his re-election campaign and rub shoulders with Sarah Jessica Parker and Anna Wintour. And, oh, yeah, he and the First Lady will tour 1 World Trade Center with Mayor Bloomberg, NY Governor Cuomo and NJ Governor Christie.

The 1 WTC visit, which is a preview to the topping-off ceremony, is scheduled for 4:30 p.m. Which means the gridlock alerts begin well before then. For instance, the PATH between Exchange Place and the WTC is being suspended between 3 p.m. and 6 p.m. Here's the scoop on traffic on city streets—watch out, West Village and Midtown!— from Gridlock Sam:

Both the President and First Lady are expected to make remarks at both campaign events.