February 2019: A Weather Roller Coaster in NYC

February was a month of wild temperature swings in New York City. Producing several days of weather whiplash, highs ranged from a frigid 21°F to an unseasonably warm 65°F. However, in the end, these extremes balanced each other out. The city’s mean temperature for the month was 36.2°F, which is only 0.9°F above average.

In terms of precipitation, rainfall was also slightly above average with twelve of the month’s 28 days posting measurable rainfall. In total, Central Park reported 3.19 inches of rain, which is 0.10 inches above normal.

Snowfall, on the other hand, was scarce. February is usually the city’s snowiest month on the calendar, but Central Park only received 2.6 inches of snow this year. Of that total, most it fell during storms that produced a wintry mix of precipitation. On average, February produces 9.2 inches of snow in the city.

February was a weather roller coaster in NYC. Credit: The Weather Gamut

Weather and Art: “Love of Winter”

Today is Valentine’s Day, a holiday when chocolate treats and images 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 white 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 the New York City area that winter. He said, “There has been none of my favorite snow. I must paint the snow at least once a year.” Then, on February 13, a blizzard hit the region. The wintry conditions inspired him to create this timeless painting.

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

Why February is Usually the Snowiest Month in the Northeast

A major snowstorm can happen during any month of the winter season, but in the northeastern United States, they tend to happen most often in February. In fact, February is the snowiest month of the year, on average, for most places across the region.

The reason for this has a lot to do with seasonal weather patterns.  That is, certain weather patterns are more likely to develop at different times of the year in different places across the country. In February, that pattern is highly conducive to producing major snowstorms in the northeast.

In general, that set up involves a large ridge in the jetstream over the west coast of the US with a deep, negatively tilted trough, in the east. The trough allows cold air from the north to spill down over the region. This means that any precipitation that falls will likely come down as snow. Another key factor is the warm water of the Gulf Stream, which flows just off the east coast.  Storms that pass over it tend to rapidly intensify. Then, following the jet stream northward, storms often encounter an area of high pressure over eastern Canada that slows their forward movement. As a result, more snow can fall over the same location boosting accumulation totals.

This is reflected in the statistics of the North East Snowfall Impact Scale (NESIS), which shows that the most category 3 or higher snowstorms occur in February. Ranked on a scale of 1 to 5, a category 3 is described as a “major” snowstorm, category 4 is considered “crippling”, and category 5 is an “extreme” event. The classifications are based on the size of the area covered, number of people affected, and snowfall totals.

In New York City, a winter season will produce 25.8 inches of snow, on average. Of that total, 9.2 inches comes in February.

Data Source: NWS

From Snow to Freezing Rain, Winter Precipitation Can Take Several Forms

The winter season can produce various types of precipitation – rain, freezing rain, sleet, or snow. The form we see at the surface depends on the temperature profile of the lower atmosphere.

All precipitation starts out as snow up in the clouds.  But, as it falls toward the Earth, it can pass through one or more layers of air with different temperatures.  When the snow passes through a thick layer of warm air – above 32°F – it melts into rain.  If the warm air layer extends all the way to the ground, rain will fall at the surface.  However, if there is a thin layer of cold air – below 32°F – near the ground, the rain becomes super-cooled and freezes upon impact with anything that has a temperature at or below 32°F.  This is known as freezing rain.  It is one of the most dangerous types of winter precipitation, as it forms a glaze of ice on almost everything it encounters, including roads, tree branches, and power lines.

Sleet is a frozen type precipitation that takes the form of ice-pellets. Passing through a thick layer of sub-freezing air near the surface, liquid raindrops are given enough time to re-freeze before reaching the ground. Sleet often bounces when it hits a surface, but does not stick to anything.  It can, however, accumulate.

Snow is another type of frozen precipitation.  It takes the shape of six-sided ice crystals, often called flakes.  Snow will fall at the surface when the air temperature is below freezing all the way from the cloud-level down to the ground.  In order for the snow to stick and accumulate, surface temperatures must also be at or below freezing.

When two or more of these precipitation types fall during a single storm, it is called a wintry mix.

Precipitation type depends on the temperature profile of the atmosphere. Credit: NOAA

The Historical Chances for a White Christmas

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 decrease.

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 the temperature.

This year, with temperatures forecast to be in the 40s on the big day, the city’s already minimal chance for snow has largely melted away.

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

Source: NOAA

The Snowiest Places in the US

Snow is a common occurrence during the winter months for many parts of the US. But, some places tend to get more than others. In fact, there are locations that see triple digit snow totals every year.

In the east, the Great Lakes region is well known for lake effect snow events. With moisture laden snow bands forming down-wind of the massive lakes, it is not uncommon for some communities to see more than 100 inches of snow each season.  For example, Syracuse, NY, on average, gets 123.8 inches of snow annually.

In the west, even more snow is par for the course in the Cascade Range of Washington state. The Paradise Ranger Station in Mount Rainier National Park holds the record for the greatest average annual snowfall in the US. At 5400 feet in elevation, they see 643 inches of snow (53.6 feet) each year.

Storm systems that move in from the Gulf of Alaska run into the Cascade Mountains and are forced upward. As they rise, the moisture in the air cools, condenses, and falls as precipitation. At lower elevations, it comes out as rain, but at higher elevations, where the air is colder, it falls as snow. Standing at 14,410 feet above sea level, Mount Rainier is the highest peak in the Cascades.

Mount Rainer National Park sees the highest average annual snowfall in the US. Credit: Hemmings

Weather Lingo: Lake Effect Snow

Winter snowstorms have a variety of names, such as Nor’easters and Alberta Clippers. It all depends on where and how they develop. In the Great Lakes region of the US, the vast bodies of fresh water influence the weather and create something known as lake effect snow.

Lake-effect snowstorms, according to NOAA, develop when cold air blows across the warmer waters of a large unfrozen lake. The bottom layer of the air mass is warmed by the water and allows it to evaporate moisture, which forms clouds. When the air mass reaches the leeward side of the lake its temperature drops again, because the land is cooler than the water. This releases the water vapor as precipitation and enormous amounts of snow can accumulate. The effect is enhanced if the air is lifted upward by local topography.

With the clouds typically forming in bands, the snowfall is highly localized. Some places can see the snow come down at a rate of more than 5 inches per hour, while nearby, others will only get a dusting. The shape of the lake and the prevailing wind direction help to determine the size and orientation of these bands.

Fetch, the distance wind travels over a body of water, also plays a key role. A fetch of more than 60 miles is needed to produce lake effect snow. In general, the larger the fetch, the greater the amount of precipitation, as more moisture can be picked up by the moving air.

The impressive depths of the Great Lakes allow them to remain unfrozen longer into the winter season than more shallow bodies of water. This combined with their massive surface area, make them excellent producers of  lake effect snow. With northwesterly winds prevailing in the region, communities along the southeastern shores of the lakes are often referred to as being in the “Snowbelt.”

Credit: NOAA

November 2018: Seventh Wettest and Fourth Snowiest on Record in NYC

November was unusually cold in New York City this year. Highs ranged from a relatively balmy 72°F to a chilly 28°F. But, with 22 days posting below average readings, the cold won out in the end. The city’s mean temperature for the month was 44.5°F, which is 3.3°F below average.

In terms of precipitation, November was a month for the record books. The city received 7.62 inches of rain in Central Park, making it the seventh wettest November on recordSnowfall was also abundant, despite the fact that it all fell during a single storm. Central Park reported 6.4 inches of snow, setting set a new daily record for the date. It was also the earliest 6-inch one-day snowfall on record for the city and the largest one-day November snowfall since 1882. Moreover, that one snow event was enough to make this November the city’s fourth snowiest on record.

New York City, on average, sees 4.02 inches or rain and 0.3 inches of snow for the entire month of November.

 

First Snow of the Season in NYC Breaks Several Records

New York City saw its first snow of the season on Thursday and it was one for the record books.

According to the NWS, 6.4 inches of snow was measured in Central Park, setting a new daily record for the date. The previous record of 1 inch had been in place since 1906. It was also the earliest 6-inch one-day snowfall on record for the city and the largest one-day November snowfall since 1882.

These superlatives came as a bit of a surprise. The forecast originally called for a wintry mix with only a dusting of snow at the onset. However, the temperature was colder than expected and the snow hung on longer. This was largely the result of an area of high pressure to the north being stronger than forecast and therefore able to funnel air toward the city that was colder than anticipated. Closer to home, evaporative cooling also played a part.  The air near the surface was very dry as the storm moved into the area. This allowed some of the snow to evaporate as it fell, cooling the air even further. As result, the change over to rain was delayed by several hours.

While pretty to see, the snow caused a number of problems around the city. Widespread travel delays and falling trees were reported across the five boroughs. As it is only mid-November, many of the trees still had their leaves. The combination of the heavy, wet, snow piling up on the foliage, weighing down the branches, and high winds was too much to bear for many trees, even the healthily ones. Many fell across streets and sidewalks as well as on top of parked cars. The city’s Parks Department has reported receiving over 2000 service requests for downed trees and dangling limbs.

This storm clearly outperformed expectations and caught the city off-guard. On average, New York City sees 0.3 inches of snow for the entire month of November.

Record breaking November snowfall topples trees in NYC. Credit: Melissa Fleming

Spring Storm Sets New Daily Snowfall Record in NYC

A spring snowstorm slammed the northeastern United States on Monday. Coming on the heels of a mild Easter weekend, it felt like weather whiplash across the region.

Here in New York City, the storm dumped 5.5 inches of snow in Central Park, setting a new daily snowfall record for the date. The previous record of 2 inches had been in place since 1871. The storm also marked the snowiest April day the city has seen in 36 years.

Despite the ground being relatively warm, the heavy, wet snow was able to accumulate because it came down very quickly. La Guardia Airport reported a snowfall rate of 2 inches per hour.

The city, on average, gets 0.6 inches of snow for the entire month of April.

Source: NWS