Monthly Archives: December 2016

The Chances for a White Christmas

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The Holiday Season is here and many people are dreaming of a White Christmas. The likelihood of seeing those dreams come true, however, are largely dependent on where you live.

According to NOAA, a White Christmas is defined as having at least one inch of snow on the ground on December 25th. In the US, the climatological probability of having snow for Christmas is greatest across the northern tier of the country. Moving south, average temperatures increase and the odds for snow steadily decreases.

Here in New York City, the historical chance of having a White Christmas is about 12%. This low probability is largely due to the city’s proximity to the Atlantic Ocean and its moderating influence on temperature. This year, despite some chilly conditions and accumulating snow earlier in the month, NYC is expecting above average temperatures on the big day.  So, the city’s already minimal chance for a White Christmas has largely melted away.

Snow or no snow, The Weather Gamut wishes you a very Happy Holiday!

Source: NOAA

Source: NOAA

Winter Solstice 2016

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Today is the December solstice, the first day of winter in the northern hemisphere. The new season officially began at 10:44 UTC, which is 05:44 AM EST.

The astronomical seasons, which are different than meteorological seasons, are produced by the tilt of the Earth’s axis (a 23.5° angle) and the movement of the planet around the sun. During the winter months, the northern half of the Earth is tilted away from the sun. This position means the northern hemisphere receives the sun’s energy at a less direct angle and brings us our coolest temperatures of the year.

Since the summer solstice in June, the arc of the sun’s apparent daily passage across the sky has been dropping toward the southern horizon and daylight hours have been decreasing. Today, it will reach its southern most position at the Tropic of Capricorn   (23.5° south latitude) marking the shortest day of the year. This observable stop is where today’s event takes its name. Solstice is derived from the Latin words “sol” for sun and “sisto” for stop.

Soon, the sun will appear to move northward again and daylight hours will slowly start to increase. Marking this transition from darkness to light, the winter solstice has long been a cause for celebration across many cultures throughout human history.

Earth’s solstices and equinoxes. Image Credit: NASA

Earth’s solstices and equinoxes. Image Credit: NASA

November 2016: Fifth Warmest November on Record for Planet Earth and Second Warmest Autumn

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Our global temperature continued its upward trend last month with November 2016 marking not only the fifth warmest November on record but also closing out the second warmest meteorological autumn ever recorded for the entire planet.

According to a report by NOAA’s National Centers for Environmental Information, Earth’s combined average temperature for November – over both land and sea surfaces – was 56.51°F. That is 1.31°F above the 20th-century average and only 0.41°F shy of the record that was set last year.

The three-month period of September, October, and November – known as the meteorological autumn in the northern hemisphere – was also one for the record books. With the season posting an average temperature that was 1.39°F above the 20th century average, it was the Earth’s second warmest September to November period on record.

While heat dominated most of the planet these past three months, some places were particularly warm. Here in the contiguous US, the autumn of 2016 was our warmest on record. Nearly every state experienced above average temperatures and eight were record warm – Colorado, Iowa, Kansas, Michigan, Minnesota, New Mexico, Texas, and Wisconsin.

These soaring temperatures are attributed to the long-term trend of human-caused climate change. Whereas El Niño gave global temperatures a boost earlier in the year, it dissipated in June. In fact, its cooler counterpart, La Niña, prevailed across the tropical Pacific Ocean this November.

Year to date, the first eleven months of 2016 were the warmest of any year on record. It is now almost certain that 2016 will surpass 2015 as the Earth’s warmest year ever recorded. Global temperature records date back to 1880.

Credit: NOAA

Credit: NOAA

Dressing for Cold Weather

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When winter rolls around, I am often reminded of the old Scandinavian saying: “There is no such thing as bad weather, only inappropriate clothing.”

Since the weather is going to do whatever it is going to do, we all need to be aware of our environment and prepare for what Mother Nature throws our way. In winter, that means cold temperatures.

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 such as hypothermia and frostbite.

To stay safe this winter, remember to bundle up in layers and wear hats and gloves to minimize the loss of body heat.

Credit: NOAA

Credit: NOAA

First Snowfall of the Season in NYC

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Let it snow! New York City saw its first measurable snowfall of the 2016-2017 winter season on Sunday with 0.4 inches reported in Central Park.

With the snow sticking only to grassy areas and parked cars, it was really just a dusting. But with holiday lights and decorations up all around the city, the softly falling flakes added to the festive atmosphere.

The timing of this first snowfall was about average for the Big Apple. Our earliest first snow event was on October 21,1952 and our latest was January 29,1973. On average, NYC gets 25.3 inches of snow for the entire winter season.

First Freeze of the Season for NYC

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After a long hot summer and mostly mild autumn, winter has finally arrived in New York City.

According to the NWS, the temperature in Central Park dropped to 30°F late Friday night. That was the coldest air the city has seen since April and marks the first freeze of the season.

Compared to average, this first nip of frosty air arrived a bit late. The city usually sees its first freeze in mid-November.  The earliest 32°F reading on record came on October 19 twice, first in 1940 and then again in 1974.  Our latest first freeze was on December 22, 1998.

Produced by a deep dip in the jet stream, these current chilly conditions are expected to last through the weekend. Then, after a brief warm-up, another shot of arctic air is forecast to hit the city late next week. Keep those coats and gloves handy!

Average Dates for First Frost

Average Dates for First Frost in New York State.  Credit: Cornell.edu

Climate Change Indicator: The Keeling Curve

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Increasing levels of atmospheric carbon dioxide (CO2) is one of the main causes of global warming. The steady rise of this potent greenhouse gas is clearly visible on the Keeling Curve, a leading indicator of human-caused climate change.

Charles David Keeling, a researcher at Scripps Institution of Oceanography, set up a CO2 monitoring site high atop Mauna Loa on the Big Island of Hawaii in 1958. This remote spot in the middle of the Pacific Ocean is well removed from the localized influences of both carbon sources (factories) and sinks (forests) that could skew the data. According to NOAA, it is the world’s oldest continuous carbon dioxide monitoring station.

When the data recorded at the site is shown graphically, it resembles a “saw-toothed” curve. This is because CO2 levels go up and down throughout the year with the life cycles of plants. Since most of the world’s landmass and vegetation are in the northern hemisphere, CO2 levels start to go down in spring when plants draw in the gas during the process of photosynthesis. Then, after reaching a minimum in the autumn, CO2 levels begin to go back up as plants die off and decay.

The curve’s long-term trend, however, has been definitively upward. Human activities, such as burning fossil fuels, have been releasing more CO2 into the atmosphere than natural carbon sinks (plants and oceans) can take out.

When first established in 1958, the CO2 level at Mauna Loa was 315ppm (parts per million). This autumn, it was more than 400ppm. To put this rapidly increasing number into perspective, consider that ice-core research shows that pre-industrial levels of carbon dioxide held steady around 280ppm from about 1000-1750 AD.

The Keeling Curve. Credit: Scripps and NOAA

The Keeling Curve. Credit: Scripps and NOAA

NYC Monthly Summary: November 2016

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November felt like a weather roller coaster in New York City this year. We had highs that ranged from a relatively balmy 72°F to a chilly 41°F. However, with 19 out of 30 days posting above average readings, the warmth won out in the end. The city’s mean temperature for the month was 49.8°F, which is 2.1°F above our long-term norm. This was the Big Apple’s 17th consecutive month with an above average temperature – its longest streak on record.

In terms of precipitation, November was unusually wet and marked the first month since July that NYC received above average rainfall.  In all, we received 5.41 inches of rain which is 1.39 inches above normal. The majority of this plentiful total fell during two separate heavy rain events. In fact, November 29th was the city’s wettest day of the year and set a new daily rainfall record with 2.20 inches measured in Central Park. Nonetheless, despite these soakers, NYC remains in a moderate to severe drought according the latest report (12/1) from the US Drought Monitor.

November 2016 was NYC's 17th consecutive month with above average temperatures. Credit: The Weather Gamut

November 2016 was NYC’s 17th consecutive month with an above average temperature. Credit: The Weather Gamut

Nov 2016 was first month since July that NYC received able average rainfall. Credit: The Weather Gamut

November was the first month since July that NYC received above average rainfall. Credit: The Weather Gamut