Officials urging everyone to stay off the roads. Here's Stephanie Ramos with the preps now under way. Reporter: Tonight, major cities across the northeast into new England bracing for the biggest snowstorm in years. Armies of municipal employees preparing for one to two feet of snow. New York City collecting 270,000 tons of salt with over 700 spreaders hitting the roads tonight. Putting everyone on alert. Please, to the maximum extent you humanly can, make alternative plans for Monday right now. Reporter: The warnings alone bringing covid vaccination efforts to a halt. New York City closing all 20 of its vaccination sites. And all city schools shutting down, going fully remote. Airlines issuing travel waivers tonight. More than 900 flights cancelled already. New Jersey issuing a state of emergency with snow emergencies beginning tonight in Philadelphia and the poconos. Stephanie, joining us from lower Manhattan. Schools up and down the eastern seaboard, as you mentioned, are closing? Reporter: Exactly. Many school districts have already been ordered to close. But that's the actual school building. With millions of students already learning virtually, many of them will be expected to log on. Stephanie, thank you. Here's the thing, this major storm is expected to last not hours but days. For more on the timing and the track, let's get right to rob Marciano. Walk us through the next several days. Reporter: Tom, you said it. It will be the duration of the storm that will be the killer as far as snow accumulation. The center of it is still over Ohio. Winter snow warnings over the big cities and into new England. The snow, rain, and sleet will get into the I-95 corridor tomorrow. Blizzard conditions in some spots, coastal flooding for sure. The big cities could easily see 6 to 12, maybe more than a foot of snow in some spots. Maybe more than two feet just northwest of New York City. It's going to be an epic storm, Tom. Rob, thank you. We turn now to the fight