November 2017 felt like a temperature roller coaster in New York City. Highs ranged from an unseasonably balmy 74°F to a chilly 38°F. But with fourteen out of thirty days posting below average readings, including two record lows, the cold won out in the end. The city’s mean temperature for the month was 46.6°F, which 1.1°F below average.
In terms of precipitation, the month was mostly dry. Only 1.58 inches of rain was measured in Central Park, marking the fifth month in a row to deliver below average rainfall. The city usually gets 4.02 inches of rain in November.
Credit: The Weather Gamut
The world of weather has some interesting words and phrases. One of these is “Rain Shadow”.
While it sounds rather poetic, a rain shadow refers to the land area on the leeside of a mountain that is exceptionally dry. Mountains act as barriers for weather systems traveling in a region’s prevailing winds, forcing them to drop most of their moisture on the windward side before they can pass.
As an air mass rises up and over a mountain, it enters an area of lower atmospheric pressure where it expands and cools. As a result, the moisture it contains condenses, clouds form, and precipitation falls. After the air mass moves over the mountain, it starts to descend the other side. The air is warmed by compression and the clouds dissipate. This means little to no rain falls on the leeward side.
Rain shadows are found all over the world, from the Tibetan Plateau in Asia to the Atacama Desert in South America. Here in the US, Death Valley is a famous example as it lies in the rain shadow of four different mountain ranges.
The Rain Shadow Effect. Credit: Kagee Commons
April 2016 was a weather rollercoaster in New York City. We had highs that ranged from a balmy 82°F to a chilly 43°F. But, in the end, the cold and warmth averaged each other out. The city’s mean temperature for the month was 53.3°F, which is only 0.3°F above normal.
In terms of precipitation, April’s famous showers were few and far between this year. The city received a mere 1.60 inches of rain in Central Park. On average, NYC typically gets 4.5 inches of rain for the month. With these parched condtions coming on the heels of scant rainfall in March, the city was listed as “abnormally dry” on the latest report (4/28) from the US Drought Monitor.
Credit: The Weather Gamut
New York City experienced some noteworthy weather in 2013. We bounced between the extremes of our coldest March in seventeen years and a July with extended heat waves. In fact, we had 17 days this summer with readings at or above 90°F, which is two above normal. Despite these superlatives, the city’s average temperature for the year was 55.34°F. That is only 0.5°F above our long-term norm.
Precipitation in the Big Apple this year was erratic. We fluctuated between our second wettest June on record and our third driest October. In the end, though, we were mostly dry. The city received a total of 46.32 inches of rain for the entire year. That is 3.62 inches below normal. Snowfall, however, was abundant. February brought the city a blizzard that dumped 11.4 inches of snow in Central Park. March and December also delivered above average snow totals. For the year as a whole, the city accumulated 29.6 inches, which is 4.5 inches above average.
On the storm front, the 2013 Atlantic Hurricane season left NYC unscathed. This was a welcome relief after being hit by major storms two years in a row – Irene in 2011 and Sandy in 2012.
Moving into 2014, we are off to an active start. A winter storm warning is currently in effect for the city as a nor’easter makes its way up the coast.
Graph Credit: The Weather Gamut