Crédito: fuente
With East Coast winter storms known as nor’easters, it often seems as if Interstate 95, which connects Washington with Baltimore, Philadelphia, Wilmington, Del., New York, New Haven, Conn., and Boston, seems custom-built to serve as the rain/snow line. This storm is no exception, though there may be more sleet than rain in some areas.
The Weather Service forecast office in Philadelphia published a map Wednesday morning showing anticipated snowfall that indicates how sharply amounts will fall off just to the east of I-95, and climb to the west, as if the highway itself is somehow halting the progression of warm air inland.
In New York City, the highway could also serve as the boundary between a snow and sleet mix, and all snow, with snowfall totals climbing to the west of the thoroughfare.
Sharp dividing lines between snow and mixed precipitation are typical with these storms, since they draw in relatively mild air from the Atlantic Ocean, which moves in just above a layer of cold, dense air at the surface. The result is snowflakes that melt as they move through the mild layer and then refreeze into ice pellets as they fall through the shallower cold air. If the cold air is eroded at the surface by onshore winds then the precipitation will become plain rain.
