Tuesday, January 01, 2013

The Cold Season's Heat Island In Philadelphia

December was one of the warmest on record in Philadelphia...and was rather warm in a number of places besides here in the Mid Atlantic.  One of the intriguing stats in our cold season so far has been the lack of subfreezing nights in the city.  December only featured seven nights of lows below 32 degrees at the Airport, which is lower than any other location in the Delaware Valley by at least four.

Our entire cold season features 12 such nights so far -- including five in November and our coldest night of the winter so far (that likely changes over the coming nights) at 28 degrees on November 26th.

The rest of the region have had colder numbers than this.  Allentown had 36 subfreezing lows since November 1st, 18 in both months, and Atlantic City has had 28 (15 in November).  It's not a matter of geography and elevation when it comes to lows at night...having a huge urban core located in your backyard, such as the Airport, matters.  This matters little when it comes to snow and precipitation as precip types deal more with air aloft than what's at the surface; however, having an average low temperature that's two degrees warmer than Atlantic City in December shows you the increasing difficulty in having record lows overall at the Airport and having cold nights compared to the cities in surrounding areas.