Saturday, December 03, 2011

Weather History: The Meme of December 5th Snow

Over the past decade, snowfall and December 5th were apparently a pretty good couple, certainly better than Kim Kardashian and Reggie Bush Kris Humphries whoever she's with.   Since 2002, we've had snowfall on this date five times.  Whether it was a minor event such as 2009 where a couple of inches fell outside of the city, or more significant storms, December 5th has acted as sort of an unofficial entry to snow starved appropriate conditions.

The first of our snowy run of December 5ths was arguably the snowiest of them.   Philly picked up seven inches of snow and as much as nine inches of snow blanketed some of the snowier locales to the north and northwest of Philadelphia in 2002, with the majority of the snow falling in the midday hours and making for an unbearable commute home (almost got stuck going up a hill, commute from Bryn Mawr to North Coventry took two hours for me).   The December 2002 event was the first official blast of what ultimately became our snowiest winter since 1995-96...and was our snowiest gold standard until two winters ago.   Seems like ancient history at this point to some extent!

Just a year later, the snowy landscape repeated itself in similar fashion with yet another storm on December 5th.   This storm brought similar accumulations to many -- but was a bit more of a storm to the north of the city, where some snowfall totals of more than a foot occurred in the region.

The snowfall with 12/5/2003 was from a similar setup -- low pressure organizing in the Gulf of Mexico, tracking northeast off of the Carolinas, spreading moisture on the north side of the low into colder air.  This storm brought 4.8" of snow to Philadelphia, 9.0" to Allentown, and one foot plus totals across Central New Jersey.  Unlike the '02 storm, there was some milder air and snow changed to rain for more folks in South Jersey. Also, the presence of an upper level low allowed some snow to linger longer, especially north of the city.

Other snowy December 5ths of recent note also include 2005, when 4.0" of snow fell over two days in a storm that fizzled somewhat more than reality, especially if you resided north of the city and got little more than flurries from that one.  2007 had a weak clipper event that gave us 1.6" of snow, which was our second largest snowfall of that winter (ugh if you like snow and double ugh if you remember that winter).   We also picked up a trace of snow at the Airport on December 5th, 2009 although the suburbs picked up more.

Believe it or not, those five December 5th's account for over a third of all the years where snow has fallen on that date since 1884 (when Philly started measuring snowfall on an official basis, not a "snow as deep as your hip" basis).   Outside of two minor events in the mid 80's, there was an awfully long stretch without measurable snow on this date...going back to 1940 when 3.5" fell in Philadelphia.   While it may seem that December 5th is a snowy date, over the years it's just a minor blip in a predominately snowless date overall.