As for snow accumulating in Manhattan, it usually doesn't because of all the heat beneath the streets and sidewalks. But it does accumulate sometimes; and if they are correct about the intensity of this storm, it will accumulate today.
ML/NJ
Yes, you’re right—they don’t shut down the schools nearly as often as in the suburbs. And you’re also right about the heat under the streets and sidewalks, really on most of the major roads and sidewalks in Midtown. But it is more than that. If you’ve been there even in a blizzard you can see that they haul most of the snow out of Times Square, for example, as quickly as it gets plowed into snowbanks.
The greater problem often is the flooding as all that melting snow on the streets and sidewalks makes for gargantuan puddles that confound crossing the street.