There’s no calm before the storm. As frenzied New Yorkers emptied grocery stores, grabbed at every last flashlight and evacuated their homes, the MTA shut down its entire transit system in anticipation of Irene walloping the city. The storm is on track to strike east of the five boroughs by 8 a.m. Transit workers began the arduous system halt — the first weather-related one in history — at noon. Bus and subway service might not get moving until well into Monday afternoon. The apocalyptic standstill leaves five million riders without a way around.