Actually, yes you can -- though you don't need to plan for several months, at least not in great detail.
The first step is to have a workable evacuation plan in place. They clearly didn't -- it was basically "use the freeways, and good luck with that." Next, you need to have a preselected destination for the refugees. They didn't. And to support the refugees, you need to have enough containerized food and shelter in place to cover the first few days. They didn't. After that, you rely on national- and state-level logistics to cover the long-term care and feeding. Even that, they didn't have.