Cold Winters and Big Pictures

The winter of 2015 was a very cold one for Central Pennsylvania.  When a rare warm day finally occurred in late March, it was the first day above sixty degrees for many of us since the last week of November.  That was 151 days.  They don't usually keep records for meteorological persistence, but this one ranks up there with some of our most persistently cold winters in half a century.  Not since 1971 has the first sixty degree day of the year come this late.  Not even the record breaking winters of 1977 and 1978 could match this year.

An ungodly cold winter, we had only two days warmer than normal from January 9 to March 13, 1978 and nine nights hit zero or below.  (Many years we have no below zero nights at all.) An aspiring young bike racer at Penn State, I was eager to get in some early season training miles and the frigid winter and cold early spring frustrated me greatly.  Yet even that frigid year, the first warm day of early spring arrived almost a week earlier than it did this year.

Like 1978, we had seven below zero nights in the Altoona area this winter.  The below zero night of March 6th was an all-time record low for the entire month many places in the Northeastern United States.  February was the coldest on record for much of north central Pennsylvania and northeastern Ohio.  Records date back to 1895.  As so often happens in North America, though, record cold in the east often coincides with record warmth in the west.  Nearly all of California and Arizona, most of Nevada, southwestern Idaho and northwestern Oregon experienced their hottest February on record.

An upper air ridge persisted for much of the winter, pulling unusually warm air from the tropics into the western states.  These same high level winds turned from the north and sucked frigid air into the eastern states from the arctic.  Often, this air came across the meteorological north pole (in what is commonly called cross-polar flow).  This is further testimony that weather is complicated and ever-changing.  Whether the planet is warming as quickly as is feared or not, it's important to remember that the weather can vary a great deal from day to day and year to year.  This is why we look at worldwide trends and keep track of long-term records in individual places. 

After a record-breaking winter like this one in Pennsylvania, there is a temptation to discount global warming.  After all, climate change deniers will argue, when it's this cold, the planet cannot possibly be warming.  But one region of the world in one single season, is only one small piece of a very large and ever-expanding puzzle.  World-wide average temperatures help us to better understand the big picture, rather than a tiny, short-lived piece like a single winter in one corner of a single country.  Long-time records of particular places remain important, too, because recognizing those averages and extremes helps us, among other things, to better understand what plants, animals or pests can survive or thrive.  Whatever extremes we must deal with, if they are changing profoundly over the long term, we would be well served to think about how we might deal with their consequences.