Sunday, December 16, 2007

The Myth Of Snow Droughts

There has been some talk about the lack of big snowfall events in recent years in the Delaware Valley in comparison to other parts of the country, with the thought that Philadelphia is in a form of a 'snow drought' that has seen the snow-starved grow ever desperate in longing for flakes of snow to quench their thirst.

The data somewhat counters the argument that recent times have been snowless, at least compared to past decades.

Part of the unfortunate reality of being located near an ocean and in the middle latitudes is the decreasing odds of receiving snowfall as one travels from north to south in the Delaware Valley. Philadelphia's 123 year snowfall seasonal average is 21.6" of snowfall, not exactly a big time number of snow. During those 123 winters, Philadelphia has had 1702 days with at least 0.1" of snowfall, an average of 13.8 snow days per winter season.

Click on the chart above to see the 'drought' of snow in Philadelphia, at least compared to last decade. The 1990's were quite a snowless decade as we had only four six inch snowfalls during the decade while this decade has featured eight so far (through the end of the 2006-2007 winter). Additionally, this decade has averaged more 'snow days' than the 1990's and is relatively close to the 1970's and 1980's in terms of number of snow days per winter.

Yes, the sleetathons that have been a part of reality the last couple of winters do make a legitimate snowstorm seem like a distant memory but just as recently as 1996-1999 we went through a several winter stretch with below normal snowfall. It may not be a perfect weather pattern for the snowstarved but we have seen some really good storms and have watched some neat weather events that haven't been a part of the landscape around here in some time.