Ice covers trees and power lines in South Austin last week. We've heard Texas' power grid came close to total failure early the morning of Feb. 15, but not exactly how close. Officials at the Electric Reliability Corporation of Texas (ERCOT), which manages the state's grid, showed its board a timeline Wednesday of events leading up to the grid’s near-collapse. That timeline showed the grid was just 4 minutes and 37 seconds away from a cascading series of events that could have left Texas in the dark for weeks — if not more. To keep the grid running, officials said, operators need to have enough power to maintain a constant frequency of around 60 hertz (you can learn more about that here). But on the evening of Sunday, Feb. 14, temperatures were falling, snow and ice were blanketing Texas and people were turning up their thermostats.