The NGM has since been retired for the ETA model, a finer version of the NGM and that has been retired for the WRF- Weather Research and Forecasting model, also known as the North American Model or NAM. The NAM is a useful forecasting tool and has a grid spacing or resolution of about 12+ miles, or four times better than the NGM or ETA.
It is a short term model that is best within 48 hours. It has limitations, but would have been welcome back when I started forecasting.
I use this model every day as a starting point in my 7day forecasts, but to be more accurate I have to also use the medium range forecast models. This model did very well with the blizzard of 2013 within 36 hours, but beyond that it was forecasting 70" of snow for Boston. No kidding!