Monday, April 16, 2007

April Nor'easter

After carving a path of destruction across the southern States, our latest "spring storm" turned toward the northeast yesterday and began to move up the Atlantic Coast. Nearing the shore in eastern North Carolina, the storm strengthened, developing a central low pressure typical of a category 2 hurricane. Counter-clockwise winds brought moisture in from the Atlantic, dropping heavy rain from Maryland to Maine.

The heaviest rain fell in New Jersey and New York, with a record deluge of 8 inches in Central Park. Combined with the phenomenal rainfall, onshore winds produced flooding from the Jersey shore to the rocky coast of Maine. Futher inland, where the moist flow met cold air and higher terrain, heavy snow fell across Upstate New York and the Northern Appalachians.

Such "Nor-easters" are most common in November or March, when the jet stream injects cold, Canadian air into the warm, moist air along the Atlantic Coast. The ongoing storm, in mid April, is the product of a late season dip in the jet which, by now, has usually assumed a west to east flow across southern Canada. But "usual" is just an average and nature pays no attention to averages.