Most tropical cyclones that move up the eastern coast of North America either veer out to sea or continue to parallel the shoreline, raking the Capes and the Canadian Maritimes. Sandy, however, is forecast to make a sharp left turn and come ashore somewhere between Washington, D.C., and New York City. While some may see God's hand in this unusual and potentially catastrophic path, there is a scientific explanation for the storm's westward jog.
Tropical storms and hurricanes respond to steering winds and pressure zones. Like a billiard ball rolling across an uneven pool table, it is deflected by high pressure ridges and attracted to low pressure troughs (bumps or dips in the table, respectively). In addition, clockwise winds that circulate around the high pressure domes will push the storm along; in this case, high pressure over the North Atlantic is creating westward winds in the mid Atlantic region that will shove the storm toward the Coast. Low pressure along an approaching cold front, now crossing Pennsylvania, offers an additional tug on the storm.
As Sandy moves toward the coast, it will push a storm surge ahead and north of its central circulation. This reflects the fact that its own large wind field is rotating counterclockwise. Since many of the bays and sounds along the Northeast Coast open to the east, the surge will be exacerbated along the edge of those shallow indentations. The combination of high winds, heavy rains and a potent storm surge may be devastating for cities and towns along the coast while inland flooding and downed trees may leave millions in the dark for the coming week (if not longer). Let's hope that the advancing cold front moves in fast enough to pick up Sandy and take her out to sea; unfortunately, the blocking high over the North Atlantic will likely prevent such a rescue.
