Saturday, November 03, 2012

Much Ado About November's Climate

November is one of those months where the last gasps of fleeting warmth can be felt and the cold season gets a more established hold on our area. Average highs and lows trend down from 61 and 43 at month's beginning to 50 and 35 by month's end. On average, Philadelphia's first official freeze takes place during the month...usually by the first week of the month.

However, the month is notoriously fickle for weather. Highs can reach 80 as late as November 15th (1993) and 70's are not uncommon at chunks of time in the month.  Every date through November features a record high of at least 70 degrees.    Since the turn of the century, we've only managed to avoid hitting 70 during November on three occasions -- 2000, 2004, and 2010. In 2001, we hit 70 seven times during the month.  For those hoping for cold, if we do hit 70 at some point later on in the month it's not the end of the world.  You just don't want a lot of warmth through the course of the month.

We've also picked up as much as nine inches of snow in a November snowstorm -- November 6th and 7th, 1953; as well as November 26th and 27th, 1898. In November 1950, parts of the state picked up significant snow from an occluded storm system that parked itself near Buffalo, which brought warmth to them and significant snows to Western PA. The city has picked up measurable snow on 57 dates through November's history -- not a huge amount and most of the snow has been minor, barring a few exceptions!

Regarding the last few Novembers, we've had a mix over the past eight years of varied weather.  Two have been cooler, one (2004) was essentially normal, and the others were milder to warmer.  The correlation of the past eight years between November and winter has not been terribly strong as our third warmest November in the data set produced the snowiest result while the second coolest November in the data set produced  the third warmest winter of the past eight years.  The only constant is the warmest November produced the warmest winter.

As long as we don't have an epically warm November, snow lovers may be able to take some solace in the winter ahead.  If November's temperature is above 49.0 for the month, odds do favor (slightly) a warm December as well.  November's average temperature has broken 49.0 ten times since 1980 and six of them have also included a warm December, most recently in 2011.