Because that stuff happens outside of your CWA and sometimes even hidden behind ISC you may never notice. Technically I have the ability to forecast all the way to CAR, but I never look at what I'm forecasting up there because it doesn't get sent anywhere. UNLESS you create an image off your whole domain.
So it could have been that they chose the coldest guidance for their area which affected NYC, or had too much QPF in an hour that had rain and snow at NYC, etc.