NEW YORK – While we haven’t been completely snow-free in the tri-state area this winter, flakes have been very few and far between. And this trend doesn’t seem to be ending anytime soon.
So why such a disappointing season for winter weather lovers? There are two main factors: climate change and la niña.
The impact of climate change is simple. Global temperatures are rising, and warmer weather means less snow. The interesting thing is that global warming does not have an equal impact on every season.
In the tri-state area, winter temperatures rise faster than any other season, so climate change is most pronounced during the coldest months of the year. Overall, the 30-year average winter temperature has risen by one degree Celsius over the past decade, significantly more than in other seasons.
Second, the global wind pattern known as la niña also helps keep snow away from the city. The term la niña is defined as colder-than-normal waters in the equatorial Pacific Ocean off the coast of South America. And, although the Pacific Ocean is a long way from here, it impacts us.
La Niña leads to global upper atmospheric wind patterns promoting generally warmer winters in the southern United States and along the East Coast. Locally, that upper-level wind, known as the jet stream, is most often north of New York City. It is the division between warm air from the south and cooler air from the north. It also serves as a forward path for storm systems.
This winter, with the jet stream heading north, most of the storm systems have moved inland. That inland track generally concentrates precipitation in the Great Lakes region. In the New York City area, it generally always means rain when a storm system passes.
For heavy snow to occur in the city, storm systems must take an offshore course, allowing sub-zero air to enter from Canada, intersect with moisture from the Atlantic Ocean, and produce lots of snow. That hasn’t happened this year, and there’s no indication that that will change in the coming weeks.
So far, no measurable snow has fallen in Central Park, New York City’s official weather station. Poor totals, all under an inch, have been recorded at a few other reporting sites nearby.
The latest recorded date for a first measurable snowfall in the park is January 29. That record was set during the winter of 1972-73. At this point, we are very close to achieving or breaking that record!
