Meteorologists started warning about this week’s killer cold as much as three weeks in advance, yet catastrophe still happened. National Weather Service officials point to lengthy and accurate forecasts with clear messages. But experts in weather and disaster say it was such a strange and huge event that it simply overwhelmed everyone. And they say human frailty and infrastructure fragility got in the way. We had problems because it was bigger than what we’d experienced in the past. We also don’t take cold as seriously as storms. And they say we just don’t like to think we’re at risk.