2012: The Year without A Winter

Sorry for the lack of posting over the past month. In addition to sports, one of my major interests is the weather, this is the reason I am Penn State majoring in meteorology. Enjoy my first non-sports related blog post about the winter, or lack there of, in The United States this year.

For much of the United States, the winter of 2011-2012 was nearly nonexistent. Many places had significantly less snow than normal along with temperatures way above averages for this time of year. After the wint er 2010-2011, this came as welcome change for some parts of the country, particularly the Northeast. Last year cities on the Eastern Seaboard got pounded with major snowstorm after major snowstorm. This included the Boxing Day Blizzard, which dumped up to 30 inches of snow in many areas including New York City (I measured 27 inches in Brooklyn, NY). After this, more massive snowstorm moved through the area, New York City had multiple storms in excess of a foot of snow. There was over a foot of snow on the ground throughout much of the City from December 26^th through mid-March. This year I came out to Central Pennsylvania for college and after last winter was expecting the worst.

As we approached winter, a sign came in October that made me think just how bad this winter was going to be, it snowed in late October. After the late October snowstorm, which left 8 inches of snow across Central Pennsylvania, I thought “the worst” that I was already fearing was much worse than originally thought. However as the winter progressed, the worst never came. Throughout winter, the late October snowstorm remained the largest snowfall of the season. There was only one other significant snowfall over the course of the winter which left behind about 6 inches of snow. Temperatures were well above average for most of the winter across much of the Eastern United States. Personally, I only needed to wear my big heavy winter coat around a dozen times or so throughout winter. In New York City, this February had an average temperature of 40.9, the second highest average temperature since records began in 1870 and every day in February except for a mere two days had temperatures above their daily average.

There are many factors that contributed to the warm temperatures and thus the lack of snow. One of these and perhaps the most important is the Arctic Oscillation Index. The Arctic Oscillation Index is a representation of the behavior of Arctic air. Arctic air masses that descend from the North Pole, or from Siberia in a cross polar flow, bring frigid cold temperatures. When these cold and dry air masses come in contact with moisture they can bring heavy snow in addition to the frigid cold temperatures. The Arctic Oscillation Index denotes the behavior of this Arctic air, when the index is positive, the cold air remains at the North Pole. When it is negative, the frigid Arctic air is released from the pole and descends upon the Northern hemisphere. Here is the trend the Arctic Oscillation Index has followed this winter (black) along with its forecast gathered from many different computer models (red).

Aside from the dip below 0 in late January – early February, the index has remained positive for all of winter. That dip along with the peculiar shape the jet stream took on is what caused the massive cold wave that hit Europe in late January – early February, which set record lows all across Europe and even brought snow to the Sahara Desert, for only the second time ever. In order for cold to descend, there needs to be a big dip, a trough, in the Jet Stream. Europe was trapped in deep trough in the Jet Stream for a few weeks. Whereas the Jet Stream over North America remained more stagnant with only small troughs which moved out pretty quickly. The Jet stream acts a boundary between air masses and blocked the Arctic air that descended upon Europe from descending upon North America as well.

The winters of both 2011 and 2012 are both very memorable for people in America, especially the Northeast, and for completely different reasons. The winter of 2011 was one of the snowiest and most tedious winters in recent memory, with multiple storms that brought snow in excess of a foot, as well as “snowmaggedon” which brought up to 30 inches to some spots. Meanwhile 2012 will be remembered as the year without a winter, and record high temperatures. In the first week of January alone, there were 1,500 daily temperature records set across the United States. After the brutal winter of 2011, the nonexistent winter of 2012 was a welcome change.