One thing can be said for sure: the tremendous storm system that impacted our region on December 19-20, 2009 will be forever remembered as 'The Blizzard of 2009'. Many areas spent days digging out from a tremendous snowfall, and easily the most significant storm system since the February 2006 blizzard which left New York City's Central Park buried in 26 inches of powder. This system was a highly anomalous storm system and an extremely difficult one to forecast. The guidance was persistent on the fact that the system would form, but the small differences aloft made the difference in each model run, with the models jumping back and forth several times even in the days right before the event. The medium range model guidance was fairly sufficient in picking up on the storm threat around 200 hours out (which is pretty impressive when you really stop to think about it). As we got closer to the event, the idea was that the storm might be suppressed to our south--something that winter weather lovers know is not a terribly bad thing. These kinds of events have a tendency to trend north at the last second, and that's exactly what this one did. The shortwave coming southeast into the Southeast US trended stronger, and the Polar Vortex trended a bit weaker, but still strong enough to keep a strong supply of cold air in the area.

The result was the guidance keying in on a major nor'easter developing off the Mid-Atlantic coast. At this point it became clear that we were on the cusp of a significant event. The guidance was still flip flopping a bit, though, on how strong the coastal low would be. A bit further west, and the area would be impacted, and a hair further east, and we would be spared any significant snow. In fact, the night before the storm system, several model runs showed nothing, as in no snow for the entire area. The majority of guidance, apart from these hiccups, trended towards the major impact of the storm system, and so the game was very much on. It's hard to try and single out the most impressive part of this storm system. Many could argue it was the strength of the low pressure, the cold air prior to it, or the amount of moisture involved. But to me it's definitely the entire setup, with a slight edge towards the cold conveyor belt banding which developed during the heart of the storm.

This banding was classic and you could see it developing as early as the night before the system in the Mid-Atlantic. As the upper level features closed off, the mid level frontogenic forcing just went through the roof off the New Jersey coast. Areas of coastal and central New Jersey were literally just pounded with band after band of frontogenically forced heavy snow. The best band of the evening began developing over long island, and you could clearly see the subsidence developing on each side of the band. The forcing literally sat still for several hours over the same areas, as the coastal low crawled off the coast. This was owing to the tremendous upper level blocking to our north, the storm had nowhere to go. The h5 shortwave closed off just off the New Jersey coast, in fact, in response to the absolute strength of the shortwave involved with our storm system. Areas within this banding (which was very widespread, although in the image above centered over long island) received obscene snowfall rates, in excess of 2-3 inches per hour.

By the time all was said and done, the 980mb low was exiting stage right and the snow wrapped up this early afternoon across all of the area. The snowfall totals ranged from moderate north and west (4"-8" in the northwest zones) to significant in Northeast NJ, SW CT, and New York City (8-14"), to crippling along the New Jersey Coast and Long Island (16-28"). Brookhaven, Long Island (site of the National Weather Service OKX) toppled its highest snow total, previous set by the Blizzard of 1978. The new total stands at 24.9". For more information you can view our complete snow archive, which features archived model data as well as radar and satellite imagery. We also have hand and graphically plotted the snow totals; and we have included the storm total snowfall graphic to your left. As a note, this post was edited on January 7th, to account for the updated totals, imagery, and snow total graphic.