Tag Archives: cold

Chilly St. Patrick’s Day in NYC

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A longstanding tradition in New York City, the St. Patrick’s Day Parade has marched in all types of weather.  This year, with temperatures in the mid-30s, parade goers had to wear a few extra layers of green.

While today was unseasonably chilly, it was not the coldest St. Patrick’s Day the city has experienced. That dubious honor, according to the NWS, is shared by both 1916 and 1967 when the high was only 26°F.  The warmest was in 1945 when the temperature soared to a balmy 75°F.

Happy St. Patrick’s Day!

Image Credit: Stutz

Image Credit: Stutz

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.

NYC Monthly Summary: February 2014

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February is generally the snowiest month on the calendar for New York City, and this year it was extreme.  With 29 inches of snow accumulating in Central Park, it was the city’s second snowiest February on record.  First place belongs to February 2010, with 36.9 inches.  On average, we typically get 8.8 inches of snow for the entire month.

Rainfall was also abundant in NYC this February. We received 5.48 inches, which is 2.39 inches above average.

In terms of temperature, the Big Apple was unusually cold. Overall, we had 11 days where our high temperature did not get above freezing.  While we also had a few unseasonably warm days, the extended periods of extreme cold brought the city’s average monthly temperature down to 31.7°F.  That is 3.3°F below normal.

Feb_TempsGraph Credit: The Weather Gamut

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

NYC Monthly Summary: January 2014

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January is typically the coldest month on the calendar for New York City and this year it was brutal.  We experienced several arctic outbreaks and saw ice form on the Hudson River.  Overall, we had twelve days where our high temperature did not get above freezing.  While there were also a few unseasonably warm days, the multiple bouts of extreme cold brought the city’s average monthly temperature down to 28.6°F.  That is 4.4°F below normal.

In terms of precipitation, the Big Apple was very snowy with 19.7 inches of accumulation recorded in Central Park. On average, January usually brings the city a total of 7 inches of snowfall.  According to the NWS, January 2014 is now ranked as NYC’s 8th snowiest January on record.  Rainfall, however, was lacking.  The city only recieved 2.57 inches, which is 1.08 inches below normal for the month.

Graph Credit: The Weather Gamut

Graph Credit: The Weather Gamut

Weather and Health: Extreme Cold

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Persistent frigid temperatures have been gripping a large part of the United States recently.  In these conditions it is important to remember that, like extreme heat, extreme cold can be very dangerous.

Extreme cold causes the body to lose heat faster than it can be generated.  Prolonged exposure, according to the CDC, can cause serious health problems, including hypothermia and frostbite.

Hypothermia is a condition of unusually low body temperature – generally below 95°F.  It impairs brain functions, limiting a victim’s ability to think and move.  Symptoms include severe shivering, drowsiness, confusion, slurred speech, and fumbling.  If left untreated, it can be fatal.

Frostbite is a localized injury to the skin and underlying tissues caused by freezing.  It can cause permanent damage and extreme cases often require amputation.  Areas of the body most often affected include the nose, ears, cheeks, fingers and toes. Signs of frostbite include, numbness, skin discoloration (white or greyish-yellow), and unusually firm or waxy feeling skin.

While the symptoms of both hypothermia and frostbite can range in severity, victims generally require immediate re-warming and professional medical attention.

To stay safe in cold weather, the American Red Cross recommends:

  • Avoiding prolonged exposure to extremely low temperatures
  • Wearing layers of clothing to keep warm
  • Using hats and gloves to minimize the loss of body heat

Ice on the Hudson River

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The New York City section of the Hudson River almost never freezes completely.  But, with high temperatures only in the teens the past few days, the river is currently churning with ice.

Near the city, the Hudson is an estuary. Fresh water flows down from the north and salt water moves in from the Atlantic Ocean to the south.  Since salt water has a lower freezing point than fresh water, it is usually only the fresh water, floating on top of the denser salt water, which freezes. This process forms ice floes – sheets of floating ice that oscillate with the tide.

The last time the Hudson River froze completely, according to historical records, was January 25, 1821.  The temperature in the city that day was a frigid -14°F.

NY Waterways Ferry on Icy Hudson River

Looking west, toward NJ, a NY Waterway Ferry navigates the Icy Hudson River.                                                                         Image sent in by David M, a Weather Gamut reader.

HusdonIceFloe

Detail of ice floes on Hudson River, January 23, 2014.                                                                        Image Credit: The Weather Gamut.

Snow and Another Blast of Arctic Air

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Heavy snow is forecast to blanket the east coast from Virginia to Maine later today.  As the storm passes, temperatures are expected to plummet.

A weakened polar vortex has allowed frigid arctic air to push southward for the second time this month. Temperatures are likely to drop below freezing as far south as northern Florida. The core of the cold, however, will be centered in the mid-west and northeast.  Here in NYC, daily high temperatures are forecast to be 15°F to 20°F below average for the remainder of the week.

While conditions are not expected to be as brutal as they were during the last arctic outbreak, the frigid weather will linger this time.  Today’s snow will likely stick around for awhile.

Weather Whiplash for NYC

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New York City was on a temperature roller coaster this week.  From unseasonably warm to brutally cold, we saw it all.

On Monday, it was 55°F in Central Park.  Then, in a matter of twenty-four hours, from 8 A.M. on Monday to 8 A.M. on Tuesday, the temperature in the city dropped 51°F!  With a low reading of 4°F on Tuesday morning, the Big Apple set a new record low for the date.  This dramatic change was ushered in by a weakened polar vortex and a deep dip in the jet stream.  After a few days of bitterly cold conditions, the mercury climbed above freezing on Friday and then continued to rise. On Saturday, the city’s temperature reached a relative balmy 58°F!  Our average high for this time of year is 38°F.

From the mid-50s to the single digits and back again in a matter of six days, it felt like weather whiplash!  Temperature swings of this magnitude in NYC are very unusual.

Image Credit: The Weather Gamut

Graph Credit: The Weather Gamut

The Dead of Winter

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The deep freeze that gripped much of the U.S. this week has begun to thaw.  The “Dead of Winter”, however, is just beginning.

While actual daily weather varies, this old saying refers to what is statistically the coldest part of the winter season.  Between January 10th and February 10th, average temperatures reach their lowest point of the year in the northern hemisphere.

These few weeks are the climatological opposite of the “Dog Days of Summer“.