TONIGHT: Critical Mass starts tonight at 6:00 p.m. As always, the Critical Mass bicycle ride will begin from Justin Herman Plaza and sprout throughout the city. SUV drivers beware! SATURDAY, SUNDAY: The North Beach Jazz Festival will land in Washington Square Park. Can you dig? And Union Street (from Stockton Street to Columbus Avenue) will be closed from 7:00 a.m., Saturday to 9:00 p.m., Sunday night. The following bus lines will be affected: 9X......