Thursday, February 11, 2010

Snowfall Shifted to Coast This Season

It's been a weird year in terms of snow in the New York Metropolitan Region. Coastal regions, including Long Island, southern Connecticut, New York City and coastal New Jersey have been hammered with snow. Inland regions, like the Hudson Valley have generally seen less snowfall accumulation. The majority of snow has fallen in two large snow storms, the blizzard that came through late in December and the large storm that passed through just yesterday (more on this storm tomorrow). Both of these storms passed out at sea, and precipitation was heaviest near the coast. This snowfall pattern is atypical. The map below shows the annual mean snowfall over the New York Metro Region.

In general snowfall follows topography -- with higher amounts falling in higher elevations inland, away from the (generally) warmer ocean. New York City averages near 25" a year. Long Island averages between 20" near the south shore and 30" near the north shore. There is a steep gradient in the lower Hudson Valley with locations nearest to Long Island Sound and New York City receiving 30" a snow per year, while locations just inland like Northern Westchester receive upwards of 45" per year on average.

The reason for the gradient as seen above is temperature. Locations nearest to the ocean are usually the warmest, and when the wind blows off the ocean temperatures tend to creep above the freezing mark of 32 F. This season, that has not been the case. Storms have passed further to the south and east allowing nearly all of the region to stay below freezing. Instead this season areas closest to the storm have received the most snowfall -- yielding high snow totals near the ocean. The map below shows the snowfall for the December 18 - 21 Blizzard. As you can see snowfall is maximized near the shoreline, nearest to the storm. Temperature was not an issue in this storm, allowing for high snowfall near the coast.

With more snow in the forecast for early next week, will the interior sections begin to make up their deficiency in snow? Will the heating power of the ocean change the snow to rain along the coast? Or, will this storm follow the track of other systems and dump heavy amounts of snow along coastal locations leaving those snow fans inland wondering where there snow has gone?

No comments: