US Weather Bureau Daily Weather Map at 1:30 AM EST on 19 March 1956.
All of this set the stage for the biggest storm, which occurred from March 18-20th. By 7:30 AM EST on the 18th, the area of snowfall attending the developing southern low centers over eastern Kentucky and southern West Virginia had enlarged to cover the Ohio Valley and had spread eastward over the Appalachians to cover most of the Mid-Atlantic states. Precipitation fell as rain over southern Maryland and southern Virginia, while snow was falling over the remainder. Snow had spread from southern New Jersey, beginning at 10:45 AM at Newark and 11:03 AM at New York City. At this time one low center was moving eastward near Quantico, Virginia, while another was also moving eastward near Danville, Virginia. During the next six hours there was little change in the area of precipitation. Showers and thunderstorms moved eastward across southern Virginia and eastern North Carolina as the southern low center moved to the coast near Elizabeth City, North Carolina and began to strengthen into a dangerous gale. Snow continued from Maryland and Delaware northward over Pennsylvania and into Long Island as far westward to Cincinnati, Ohio, as the northern low center moved to southern Delaware.
By 1:30 AM on the 19th, the surface low system was off the coast, some distance southeast of New Jersey, moving northeastward. Snowfall continued over the New York City area, New Jersey, Delaware, Maryland, and eastern Pennsylvania. On the 19th the snow spread over southern New England. Meanwhile, the low pressure cyclonic center moved northeastward along the coast at an ever-slowing rate toward Nantucket, finally passing to the northeast of that point and filling on the 20th, while a new center formed farther east near Sable Island. It is interesting to note that the duration of precipitation in the form of snow at Philadelphia, Trenton, Atlantic City, Newark, and New York City (Battery) ranged from 31 hours at Philadelphia to 35 hours at Atlantic City. Farther east, over southern New England, the duration ranged from 26 hours at New Haven to 24 hours at Boston. In spite of this, the depth of new snow added by the storm was remarkably uniform, measuring 12 to 13 inches at Trenton, New York City, New Haven, Bradley Field (Hartford), and Boston. A notable exception was the 18 inches that fell at Newark. The final snowfall at Blue Hill was 19.5 inches and the maximum snow depth on the ground reached 25.3 inches on the 20th. At the Observatory a peak gust of 63 mph from the NE was measured on the 19th. All in all, this was one of the most severe and deadly snowstorms in southern New England history. Approximately 162 people were killed and most towns were left paralyzed under deep snowdrifts as high as 14 feet.
As if this wasn’t enough the blizzard of March 18-20th was followed by another snowfall of 12.3 inches at Blue Hill on March 24th with a final 2.9 inches falling on the 29-30th. Many of us remember shoveling much of the month, fortunately under a warm March sun!
Credit for the graphics shown here goes to the NOAA Central Library archive of daily weather maps, and much of the content of this article was derived from Mook and Norquest, 1956. Mook and Norquest acknowledge the help of Dr. David Atlas who provided radar data from the radar then located on top of Great Blue Hill with the radar office in a Quonset hut in the backyard of the Observatory.

