Spain began the new year battling Storm Filomena, a once-in-a-generation weather event that blanketed Madrid in snow and paralyzed the economy. Health workers were stranded, supermarkets shut, and the army was called in. At least four people died. “Now, consider a government or company that knew two weeks ago there was a risk that this would happen,” said Francisco Doblas-Reyes, a physicist at Barcelona’s Supercomputing Center. “Knowing the risk that a 1-in-20-year event was going to happen would have given more possibilities to prepare.”