Think the East Coast Blizzards Were Bad This Year? Try 1947

Given this past winter’s weather quirks, a quick glance over the proverbial shoulder seems in order.  While there are always dozens of frozen blasts throughout the winter season, those that garner the most attention are naturally those that hit major metropolitan areas, and for good reason.  Just a few inches of frozen or semi-solid precipitation can stall traffic, tie up commutes, shut down power to buildings, close offices, and carry a hefty price tag for clean up, snow removal, emergency services, and lost man-hours.  This effect is, of course, exacerbated when the accumulation is measured in feet rather than inches.  There have been many, many serious winter storms since the beginning of reliable data collection systems, but one in more recent history comes to mind first.  The place?  New York City. The date?  December 26-27, 1947.  The heralded “big snow” crippled the city.  But how did this blizzard form?  What exactly is a blizzard, anyway?  What makes New York City such a prime target for severe winter weather?

All storms are not created equal.  According to the United States Search and Rescue Task Force, “Blizzards are severe storms that pack a combination of blowing snow and wind resulting in low visibilities.  While heavy snowfalls and severe cold often accompany blizzards, they are not required.  Sometimes strong winds pick up snow that has already fallen, causing a blizzard.”  The National Weather Service (NWS) defines a blizzard as “large amounts of falling or blowing snow with winds in excess of 35 mph or visibilities of less than ¼ mile for an extended period of time” (greater than 3 hours).  Interestingly, the Weather Bureau did not qualify the 1947 storm as a blizzard since it lacked the typical severe winds.  The New York City area is especially susceptible to harsh, precipitative squalls because it lies right in the line of an infamous set of pressure systems known as Nor’easters. 

Nor’easters are generated along the Eastern seaboard from Virginia to Maine because cold air (an obvious characteristic of Temperate Zones,) gathers both near the ground and in the upper atmosphere.  Warmer air comes in from over the Atlantic, bringing copious amounts of water vapor with it.  When the cold and warm air meet, the cold air is forced downward, and the warm air up.  It eventually cools and can no longer sustain all the water vapor it once carried.  This can lead to major snowfall along with other serious conditions such as freezing rain, sleet, and ice storms.  And, just in case these looming threats were not enough to look forward to, there is also the ubiquitous howling wind which may drift the snow many feet high and can make a tense situation absolutely unworkable.  According to the NWS, New York’s geographic location means that its citizens can expect a major storm of at least sixteen inches every nine years or so. That statistic is based on historical data as well:  New York has been hit with twenty-three such storms since 1798. 

1947 was a particularly bad year.  So bad, in fact, that a midwinter fall broke the record for most snow fallen set in 1888, and it held that record until 2006.  The flakes began to fly in the early morning hours of Friday, December 26, gathering speed until the rate reached about three inches per hour.  Within twenty-four hours, a respectable 26.4 inches lay on the ground.  In fact, a New York Times article from April 9, 1948 said that overall, the snow cost the city “millions of dollars.”  The storm was remarkable not only for the amount of snow that fell, but also in its subtle mercy, since not much wind accompanied the fall. As a result, very little drifting occurred, and thus the storm lacked the lethality often attendant to real monster blizzards.  Additionally, the temperatures remained relatively high, ranging in the twenties.  More severe blizzards have had temperatures at or below zero, along with screaming winds which add to both the danger and the wind chill.

Though it could have been much, much worse, all that snow did damage and stranded unfortunate city-dwellers. Weather.com offers some more details about the storm itself. While storms can come in all shapes and sizes, the 1947 blizzard was a type known as a “mesoscale”:  instead of a fairly even distribution over a vast area, this “big snow” fell squarely over New York City.  Manhattan received 26.1 inches; both the Bronx and Staten Island had 25; 27.2 in Brooklyn; 24.6 in Queens.  Very little snow from this system fell anywhere else; in fact, it was reported in the Times on April 9, 1948 that the rest of the New England coast received less than ten inches.  Its sheer concentration (as well as its inconvenient location) is what makes it of such note. 

The NWS’s National Center for Environmental Prediction (NCEP) has been gathering data from historical storms dating back to the 1950s.  The NCEP has formulized its findings into a scale which categorizes storms from zero to five, based on the impact each one had on its respective area.  Since New York is so densely populated, and since so much snow fell, the 1947 tempest received a rating of three (wind speed, duration and the like do not factor into the formula).

Curiously, the previously mentioned article suggests that a lot of snow can generate some surprising benefits such as insulating the ground, clover, and grass from a deep freeze, protecting fall sown seeds, ensuring full reservoirs, and providing moisture for spring. Considering the severity of the past winter, it may be a very green spring in New York and Washington D.C. this year!