The weather usually associated with winter in the eastern United States has not really taken hold this year. One of the reasons for this involves something called the North Atlantic Oscillation (NAO).
This is a natural phenomenon that affects the position of the jet stream and weather patterns thousands of miles away. Based in the North Atlantic Ocean, it is driven by the pressure differences between the semi-permanent Icelandic Low and Azores/Bermuda High.
When the pressure difference between these two systems is low, the NAO is said to be in a negative phase. This means the winds of the jet stream are relatively relaxed and cold air from the north can spill down into the eastern US. The positive phase of NAO is characterized by a strong pressure difference between the two systems and a robust jet stream that keeps cold air bottled up in the northern latitudes.
Fluctuating between positive and negative, the strength and duration of these phases vary. This winter, however, the positive phase has been occurring more often and lasting longer than the negative phase. That is why the eastern US has been experiencing prolonged warm spells separated by a few brief blasts of cold air.
Unsurprisingly, this season’s soaring temperatures have sparked many important conversations about global warming. But as weather is extremely variable, no single warm day or week can be linked (at this time) to our changing climate. That said, anomalously warm events are happening more often, which is consistent with the long-term trend of human-caused climate change. 2016, for example, was this planet’s third consecutive warmest year on record.
Typical impacts associated with the positive phase of NAO. Credit: NOAA/NCDC
NAO observations, Nov 2016 to date. Credit: NOAA/CPC
It is only February, but it felt more like May in New York City on Friday. The temperature in Central Park soared to 70°F, which is a whopping 26°F above average.
According to the NWS, this was the first time in twenty years that the city had a reading in the 70s during the month of February. However, it was not a record breaker. That honor belongs to February 24, 1985 when the mercury hit 75°F.
The primary driver of these balmy conditions is a strong Bermuda High off the east coast of the US that is funneling warm southern air into the region.
Many New Yorkers got out to enjoy this early spring preview and described it as “amazing” or “unbelievable”. Personally, it felt a little surreal to see rowboats out in Central Park during a month when sledding and ice-skating are usually the norm.
That said, a chilly change will be in the air later this weekend when temperatures are expected to return to more seasonable levels.
Rowboats on The Lake in Central Park on Feb 24, 2017 when the temperature hit 70°F in NYC. Credit: Melissa Fleming
On Monday night, a group of teenagers fell through the thin ice on a body of water in Central Park known as The Pond. Luckily, all were saved by the quick actions of good samaritans and NYC’s outstanding first responders. That said, this unfortunate incident is a salient reminder about safety issues for all winter activities that take place on the ice.
Winter is usually the time for ice-skating, ice-fishing, cross-country skiing, and snowmobiling. This year, however, unseasonably mild conditions have limited the opportunities for many of these popular pursuits. While there have been a few blasts of cold air, they have not lasted long enough to produce ice that can sustain significant weight. Below are some guidelines on how thick the ice needs to be to support different activities.
It is also important to remember that the thickness of ice can vary dramatically at different locations on the same body of water. Therefore, it is always best to follow the instructions of local officials and posted signs. Moreover, as the old saying goes: “If in doubt, don’t go out!”
Between picnics in the park and overflowing crowds at local ice cream shops, it felt more like late April than mid-February in New York City this holiday weekend.
The temperature in Central Park soared to 63°F on Saturday and 65°F on Sunday. Both days missed setting a new record high by only a few degrees. Overnight lows were also unusually mild. According to the NWS, a new record warm minimum temperature was set on Sunday with a reading of 53°F. The previous record of 49°F was established in 1997.
The city’s normal high for this time of year is 43°F. Its normal low is 30°F.
Any snow that was left over from the storm earlier this month was no match for these spring-like temperatures. More abnormally warm conditions are expected later this week, so keep that frisbee handy.
Not much snow left in NYC after a weekend with temperatures in the 60s. Credit: Melissa Fleming
Our global temperature continued its upward trend last month with January 2017 marking the third warmest January ever recorded on this planet. Only the Januarys of 2016 and 2007 were warmer.
According to a report by NOAA’s National Centers for Environmental Information, Earth’s combined average temperature for the month – over both land and sea surfaces – was 55.18°F. That is 1.58°F above the 20th-century average.
January was also the 385th consecutive month with a global temperature above its long-term norm. That means the last time any month posted a below average reading was December 1984.
While heat dominated most of the planet this January, some places were particularly warm, including the eastern half of the United States and most of Canada. For the contiguous US as a whole, it was our 18th warmest January on NOAA’s books.
Building on the qualitative aspect of my talk, “The Art and Science of Climate Change”, this poster project quantified the influence climate-art has on people’s opinions. As Lord Kelvin said, “When you can measure what you are speaking about, and express it in numbers, you know something about it…”
Using Survey Monkey, I conducted a national poll where participants were asked comparison questions about the influence of traditional graphs vs. artistic interpretations of climate change. The graphs were sourced from the IPCC’s fifth assessment report and the artwork came from both photojournalists and conceptual artists.
When compared to a graph, the different styles of art received different reactions. On average, however, a significant number of the participants (34%) related more to the issues of climate change via art than through traditional charts and graphs. Overall, 64% of participants said art had changed the way they thought about a subject in the past.
These results show art to be a powerful tool of communication that helps to broaden the public conversation on climate change. They also highlight the fact that a variety of visual outreach methods are needed to reach the entire population on this critical issue that affects us all in one way or another.
The survey shows art can help broaden the public conversation on climate change. Credit: The Weather Gamut.
Today is Valentine’s Day, a holiday when images of cupid and hearts abound. But for me, it is George Bellows’ Love of Winter that always comes to mind as we mark the mid-point of what is usually New York City’s snowiest month of the year.
A longtime personal favorite, this 1914 painting captures the spirit of those who embrace the season. Filled with the blurred movement of skaters on a frozen pond and accented with spots of bright color that pop against the snow, it conveys the joy of being out in nature on a cold winter day.
While Bellows is better known for depicting scenes of boxing matches and urban life, art historians say he enjoyed the challenge of painting the varied lighting conditions produced by a snow-covered landscape. In fact, he wrote a letter to a friend in January 1914 complaining about the lack of snow in NYC that winter. He said, “There has been none of my favorite snow. I must paint the snow at least once a year.” Then, about a month later, his wish for snow was granted and this picture was created.
Love of Winter is part of the Friends of American Art Collection at the Art Institute of Chicago.
“Love of Winter”, 1914 by George Bellows. Collection of the Art Institute of Chicago
Just like real estate, weather is all about location. In the northeastern US, a special set of coordinates known as “The Benchmark” (40°N 70°W) can help identify the type of impacts a winter storm will have on the region.
When a low-pressure system travels west of this position, coastal areas will see more rain than snow as the storm pulls relatively warm marine air onshore. Further inland, where the air is colder, snow is more likely.
If a storm tracks east of the benchmark, it is essentially moving away from land and less warm air is pulled onshore. Some light snow will fall along the coast, but usually not very much.
When a system moves directly through the crosshairs of the benchmark, coastal communities in the region can expect a major snow event. This is exactly what happened with the storm on Thursday that dumped heavy snow across the area.
The first major winter storm of the season rolled through New York City on Thursday. The powerful, but quick hitting, system brought strong winds and heavy snow to the area.
According to the NWS, 9.4 inches of snow was measured in Central Park. The city, on average, gets 9.2 inches of snow for the entire month of February.
This classic nor’easter intensified quickly as it moved up the coast, drawing energy from both the clash of different air masses and the relative warmth of the Atlantic Ocean. Its unusually strong convection was reflected in the high number of thundersnow reports across the region.
As powerful as this storm was, it could have produced even higher snow totals if there was an area of high pressure to the north to block or hold it in place longer.
Nonetheless, this event has secured its place in NYC weather history. Never before has the city experienced a major snowstorm ( >6 inches) less than 24 hours after setting a new record warm temperature. This was a case of extreme weather whiplash!
More than 9 inches of snow blanketed Central Park, NYC on Feb 9, 2017. Credit: Melissa Fleming.
Walking around New York City on Wednesday, it was difficult to remember that it was still February. The temperature soared to 62°F in Central Park, setting a new record high for the date. The previous record of 61°F had been in place since 1965.
This was the second time this winter that a daily high-temperature record was broken in the Big Apple. The city’s normal high for this time of year is 40°F.
Venturing out without coats and enjoying lunch alfresco, many New Yorkers took full advantage of the unseasonable warmth. These spring-like conditions, however, will be short-lived. The city’s first major snowstorm of the season is expected to hit early Thursday morning. Get ready for weather whiplash!
Temperatures soared to record levels in NYC on Feb 8th. Credit: The Weather Gamut