Both Baltimore and Washington, D.C. set new winter snowfall records this winter as a result of the third blizzard of this season on 9 and 10 February 2010. The previous winter record was the winter of 1898-1899. Time magazine and the NY Times have claimed that this new record snowfall is probably due to global warming. If that followed so simply, then should it not be likely that the previous winter record was also due to global warming? In other words, that simple logic would imply that the winter of 1898-1899 was an equally warm period. Hmmm......last I knew the catastrophic man-made global warming alarmists were saying that the warming which occurred in the late 20th Century was unprecedented. I do not think they want us to think the Time and NY Times logic through to the conclusion that 1898-1899 were equally warm!
The claim they made is essentially that the warmer air due to global warming will hold more moisture and therefore can provide more snow in the winter. They overlook the fact that the Washington and Baltimore areas are near the Atlantic and generally have plenty of precipitation in the winters. Most of that precipitation is in the form of rain and sleet most winters.
Let us consider the case for Washington, D.C.: The only month with an average temperature below freezing is January and its average temperature is barely below freezing, being 30.6 degrees F. February at an average temperature of 33.6 degrees F and December at an average of 35.4 degrees F are the next coldest months. It is hardly a wonder that most winters have more rain and sleet than snow. But, the December relative humidity in the morning is 79%, January averages 77%, and February averages 78%. There is hardly a lack of humidity to turn into snow or rain. This humidity is lower than the summer humidity, which in June is 84%, 86% in July, and 89% in August. The afternoon humidity in December is 58%, in January it is 59%, and in February it is 54%. The December and January afternoon humidities are the highest of the year! December and January have the highest number of cloudy days in the year, followed by February and March. December averages 3.2 inches of precipitation, January 2.7 inches, and February 2.8 inches.
Commonly, 1 inch of rain is about 6.25 inches of snow. If all December average precipitation were in the form of snow, D.C. would have 20.0 inches. The average January snow would be 16.9 inches and the average February snow would be 17.5 inches. In fact, from 1971 to 2000, Washington, DC averaged 15.2 inches of snow each year, which is less than the potential of any of our winter months. The limit on snow in DC is not the humidity of the air. It is the temperature of the air! Global warming would not make the winter air temperatures colder! In fact, the falsified land surface temperature records usually indicate the greatest amount of the claimed recent warming occurs in the winter.
The amount of annual snowfall is very highly variable. Before this winter, the snowiest winter in Washington D.C. was that of 1898-1899. But, the previous winter of 1897-1898 had only 0.1 inch of snow! That winter tied the winter of 1997-1998 for the record for least snow. Note that in 1997 and 1998 we were already being told that these were years of unprecedented warmth. If global warming causes heavy snowfall, why was that winter tied for the least snow since 1870?
The blame-it-on-mankind global warming alarmists never miss a chance to blame uncommon weather on mankind. But, if they had only examined their assumptions a little bit, they would have seen the foolishness of the argument they put forth as the explanation for the heavy snowfall of the winter of 2009-2010 in Washington, D.C. and Baltimore.