Tag Archives: winter

Technical Weather Terms Go Viral

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This winter produced some record cold temperatures and significant snowfall across the eastern two-thirds of U.S.  It also brought a few technical weather terms into our mainstream vocabulary.

In January, bitterly cold arctic air moved south over a large section of this country and the term “polar vortex” became ubiquitous.  Although it sounds ominous, the phrase literally describes what it is – a pattern of winds spinning around the North Pole.

More recently, as a powerful nor’easter moved up the eastern seaboard, “bomb” became a weather buzzword.  Also known as “explosive cyclogenesis”, it is a meteorological expression that describes the rapid intensification of a low-pressure system.  More specifically, it means the surface pressure of a system is expected to drop by at least 24 millibars in twenty-four hours.  In general, the lower the pressure, the stronger the storm.

The weather phenomena described by these phrases can occur every winter.  Why did they become so popular this year?  Was it because they happened more frequently this season?  Is it because they work well as catchwords or tags on Twitter?  Perhaps, it was a bit of both.

Volatile March Temperatures in NYC

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Up and down and back again, this was a volatile week for temperatures in New York City. Overall, it felt like we were on a weather roller-coaster.

On Tuesday, the high temperature in Central Park was a balmy 66°F – the city’s warmest day of the year so far.  Two days later, we were reminded that it is still winter when the mercury only made it to 32°F.  Today, the temperature rebounded to 58°F, but it is forecast to tumble into the mid-30s again tomorrow. Our normal high for this time of year is 49°F.

As jarring as they may be, these large temperature swings are par for the course in March. Transitioning from winter to spring, warm air in the south is expanding quickly while cold air lingers in the north.  As a result, temperature gradients can be very tight and local conditions can change abruptly.

Graph Credit: The Weather Gamut

Graph Credit: The Weather Gamut

Winter 2013-14: The 34th Coldest for Contiguous U.S.

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The winter of 2013-14 has been long and cold for many parts of the United States. For the nation as a whole, it was our coldest winter since 2009-10, but not a record breaker.

According to NOAA’s National Climatic Data Center, this meteorological winter (Dec-Feb) was the 34th coldest on record for the contiguous U.S.  With an average temperature of 31.3°F, the country was 1°F below its long-term norm.

While the Northeast and Midwest experienced extended bouts of frigid temperatures and abundant snow, the West was unusually warm and dry.  This difference, produced by a highly amplified jet stream, balanced out the national average.  Nonetheless, it is interesting to note that even though this winter was among the top ten coldest for a few mid-western states, none posted an all time record cold season.  California, by contrast, experienced its warmest winter on record.

Near Record Ice Cover on the Great Lakes

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Persistent frigid temperatures this winter across the Mid-West and Northeast have caused many rivers and lakes to freeze.  These include the Great Lakes – the largest group of fresh water lakes on the planet.

According to NOAA’s Great Lakes Environmental Research Laboratory, 91.8% of the Great Lakes are currently covered with ice.  That is the second highest percentage on record.  The largest was 94.7% in 1979. On average, peak ice coverage each winter is roughly 51%.

This extensive ice cover has its pluses and minuses.  On one hand, it has reduced the amount of lake effect snow – the heavy precipitation produced when cold air blows across the expansive and relatively warm lake water.  When the lakes are frozen, moisture cannot be evaporated and this process shuts down.  On the other hand, it has slowed shipping traffic, which has economic impacts.  Also, given their massive size, the frozen lakes will likely keep regional temperatures cooler than average this spring.

While this year’s ice cover on the Great Lakes is near record-breaking, researchers say the ice extent varies annually and that there has been an overall decline since the early 1970’s.

Ice covers more than 90% of the Great Lakes. Image Credit: NOAA/Great Lakes Environmental Research Laboratory.

Ice covers more than 90% of the Great Lakes.                                                                                      Image Credit: NOAA/Great Lakes Environmental Research Laboratory.

Cold Winters and Climate Change

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Cold and snowy weather – the type that has dominated this winter across much of the United States – can lead some people to question the validity of global warming.  According to scientists, however, these frosty conditions are not entirely unexpected in our changing climate.

Cold temperatures are a natural part of winter.  Our astronomical seasons – winter, spring, summer, and fall – are generated by the tilt of the Earth’s axis and the movement of the planet around the sun.  During the winter months, our hemisphere is tilted away from the sun and receives the least amount of solar energy all year.  So, even as our average global temperature goes up, winter will continue to be cold relative to the other seasons.

The tilt of the Earth during different seasons. Image Credit: NASA

The seasons are caused by the tilt of the Earth as it rotates on its axis and revolves around the sun.  Image Credit: NASA.

Although global warming will not change the tilt of the Earth’s axis, it is affecting the moisture content of our atmosphere.  Increasing levels of greenhouse gases are warming the air and allowing it to hold more water vapor.  As a result, when storms develop they produce more intense precipitation.  In winter, that includes snow, sleet, and freezing rain when given the appropriate temperature range.

This year, we have experienced a number of arctic outbreaks from the now famous polar vortex.  Each one provided a deep pool of cold air that helped produce significant snowfall throughout the eastern two-thirds of this country. While the occasional cold snap is part of the season’s natural variability, they have been lasting longer recently. Some scientists suggest this is the result of arctic amplification – a tendency for the arctic to warm more rapidly than the mid-latitudes. As the temperature difference between the two regions decreases, the jet stream slows down and takes a wavier shape. The larger the waves, the slower they move, and the weather associated with them – warm or cold – stays in place longer.

It is also important to remember that climate change is a complex global phenomenon that involves much more than what is happening in our own backyards.  While it has been a brutally cold and snowy winter for many of us in the Northeast and Midwest, the western states are in the midst of a serious drought and Alaska has been experiencing record high temperatures.  Beyond our borders, much of the rest of the world has been unusually warm.  For example, the recent Olympic Winter Games in Sochi, Russia were the warmest in history. In the southern hemisphere, Australia sweltered through a record heat wave in early January. Experts say it is not unusual to see regional variability with climate change, but overall the Earth’s atmosphere is unequivocally warming.

This short video by the Yale Climate Forum highlights the issue of cold weather and climate change in the context of the 2013-14 winter season….

Video Credit: Yale Climate Forum and YouTube

An Early Spring Preview

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This weekend, much of the eastern United States is enjoying a welcome relief from what has been a long and brutal winter. Temperatures are soaring well above average across the region making it feel like spring.

In New York City, the high temperature in Central Park reached 54°F yesterday and it is expected to climb into the mid 50s again today.  Last Sunday, the mercury only made it to 30°F.  Our normal high for this time of year is 43°F.

With feet of snow on the ground, these mild conditions have caused rapid melting throughout the area.  Although this has caused ice to fall from tall buildings and some localized flooding, many winter-weary New Yorkers are enjoying this early spring preview.

This warmer weather can be easy to acclimate to, but it is still February and winter is not letting go just yet. Cold conditions, including another arctic outbreak, are expected to return over the next few days.

The first patches of green lawn appear on Central Park's Green Meadow as temperatures soar and snow melts. Image Credit: The Weather Gamut.

The first patches of green lawn seen in weeks on the Sheep’s Meadow of Central Park are revealed as temperatures warm and snow melts.    Image Credit: The Weather Gamut.

Another Snowstorm Slams NYC

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A massive winter storm walloped the East Coast of the United States yesterday.  The impacts of snow, sleet and freezing rain were felt from Georgia to Maine.

Here in New York City, the storm came in two parts.  The first round brought us 9.5 inches of snow.  Coming down at a rate of 2 to 3 inches per hour, it piled up quickly.  Following a lull in the afternoon, round two produced heavy rain, thunder and lightning, and another 3 inches of snow.  In the end, this classic nor’easter dumped 12.5 inches of heavy, wet snow in the Big Apple.

So far this February, the city has received 25.7 inches of snow.  On average, we usually get 25.1 inches for the entire winter. This season, to date, we have accumulated 54 inches of snow in Central Park, making it our 9th snowiest on record.

More snow is forecast for the weekend.

Balmy Weather at the Winter Olympics

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Frigid temperatures and abundant snowfall have been dominating this winter season across most of the continental U.S.  In Sochi, Russia, however, the XXII Olympic Winter Games have had a more spring-like feel.

Russia, famous for cold and snowy winters, has a few relative warm spots.  Sochi is one of them. Situated between the Black Sea and the Caucasus Mountains, it has a subtropical climate that supports palm trees.  While there is usually snow in the mountains, the city’s average temperature for this time of year is about 50°F.

This week, temperatures in Sochi have been running above average.  Today, the mercury hit 59°F and highs are forecast to be in the 60°s for the rest of the week.  Even in the higher elevations of the so called “mountain cluster” venue – site of all the skiing, snowboarding, and sledding events – temperatures have been well above freezing during the day.  This mild weather is turning the hard packed competition snow into slush – creating difficult conditions for many of the athletes.

While the current balmy weather has caused some delays, it has not hindered the Games. With hundreds of snowmaking machines and a stockpile of natural snow stored from previous years, officials say they are prepared to supply as much snow as necessary.  That said, these Winter Olympics are on track to be the warmest in history.

Average minimum temperatures for January and February from 1911-2011 for all the locations that have hosted the Olympic Winter Games. Image Credit: NOAA

Average minimum temperatures for January and February from 1911-2011 for all the locations that have hosted the Olympic Winter Games.    Image Credit: NOAA.

Weather and Art: Love of Winter

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Winter, like all seasons, has its pluses and minuses. With freezing temperatures and accumulating snow, it can produce travel problems and other difficulties. On the other hand, it also creates the opportunity for a variety of outdoor activities like skiing, sledding, ice-skating, snowshoeing, and of course, the Winter Olympics.

Love of Winter, a painting by George Bellows from 1914, captures the spirit of those who embrace the season. A personal favorite, it portrays the movement of skaters on a frozen pond.  Filled with activity and color, the scene conveys the joy of being outdoors on a crisp winter day.

"Love of Winter", 1914 by George Bellows. Collection of the Art Institute of Chicago

Love of Winter, 1914 by George Bellows. Oil on Canvas (32.5 x 40.5 inches).                                                    The Art Institute of Chicago, Friends of American Art Collection.

A Wild Week of Wintry Weather

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Coming on the heels of a very snowy January, a series of winter storms slammed the midwest and northeastern U.S. this week.  From snow to sleet to freezing rain, the region saw a bit of everything.

Here in New York City, Monday’s storm dumped 8 inches of heavy, wet snow in Central Park – setting a new daily snowfall record. Only two days later, another weather system brought the Big Apple a wintry mix that included 4 inches of snow topped with about 0.25 inches of ice.

These two storms brought the city’s monthly snowfall total up to 12 inches and it is only the first week of February.  On average, we usually receive 8.8 inches for the entire month. Overall, local snowfall has been running above average this winter season with 40.3 inches of accumulation to date.

While more snow is on deck for the weekend, NYC is not expecting significant accumulation, contrary to earlier reports.