Was the NAM’s blizzard forecast really that good?
Oh, the NAM. The source of so many colorful snowfall projections that spread like wildfire across social media. The weather model that gives meteorologists fits multiple times per season. The weather model that can pick out thunderstorms two days in advance, and completely mishandle a snowstorm at a 24 hour lead time. And now, the weather model that absolutely nailed the forecast for the Blizzard of 2016 in New York City.
The Blizzard of 2016 will likely go down as one of the most effectively modeled snowstorms in meteorological history. The signal for the storm system was evident as far as 8 days in advance (arguably longer via long range pattern recognition). Long range ensemble guidance and even individual operational model runs showed the storm systems evolution consistently 6 to 8 days in advance, with increasing agreement on a major low pressure system off the East Coast. And, up until Day 5 or so, the agreement was relatively unanimous among major global models such as the GFS, Euro and Canadian.