January is usually the coldest month of the year – the so-called dead of winter. There are times during the month, however, when temperatures soar well above average. This is known as a “January Thaw”.
This type of weather phenomenon typically occurs after an extended cold blast and is marked by temperatures at least 10°F above normal for few days. It does not necessarily occur every year, but when it does, it is usually in mid to late January, hence the name.
Credit: Melissa Fleming
The extended cold wave that has been gripping New York City earned a place in the record books as it came to an end on Tuesday when the temperature climbed above freezing for the first time since Christmas.
Brutally cold temperatures dominated the end of 2017 and beginning of 2018 in NYC. Credit: Melissa Fleming
In all, the city experienced fourteen consecutive days with temperatures below 32°F. That, according to the NWS, is the third longest sub-freezing cold streak ever recorded in Central Park. The coldest day came on January 6, when the mercury only made it to 13°F. The wind chill made it feel even colder.
These unusually frigid conditions were the result of a deep dip in the jet stream and a lobe of the polar vortex reaching southward over much of the eastern US. While a brief warm-up is expected over the next few days, it is still January so keep those hats and gloves handy.
Credit: NWS
A massive winter storm – known by some as Grayson – slammed the eastern US on Thursday. Producing heavy snow and strong winds, its impact was felt from northern Florida to New England.
Here in NYC, the storm dumped 9.8 inches of snow in Central Park, setting a new daily snowfall record for the date. The previous record of 4 inches was in place since 1988. The city, on average, gets 7 inches of snow for the entire month of January.
Developing as a classic nor’easter, this storm became an over-achiever as it rapidly intensified over the warm waters of the Gulf Stream. It underwent a process called Bombogenesis, the threshold for which is a drop in pressure of 24mb in 24 hours. This storm dropped 59mb in 24 hours, producing very powerful winds. At JFK airport, wind gusts up to 55mph were reported.
The snow left behind by this storm will not be going anywhere anytime soon. A re-enforcing shot of cold arctic air moved in behind the storm and dangerously cold temperatures are expected to remain in place through the weekend. Bundle up!
The first big winter storm of 2018 brought NYC 9.8 inches of snow. Credit: Melissa Fleming
If you enjoy winter and a good snow day, here are some fun facts about snow to ponder when the flakes fall:
Enjoy the snow!
Snowflakes come in a variety of shapes, but all have six sides or points. Credit: Wilson “Snowflake” Bentley
The Earth reached its Perihelion today at 5:34 UTC, which is 12:34 AM Eastern Standard Time. This is the point in the planet’s orbit where it comes closest to the Sun.
This annual event is due to the elliptical shape of the Earth’s orbit and the off-centered position of the Sun inside that path. The exact date of the Perihelion differs from year to year, but it’s usually in early January – winter in the northern hemisphere. The Earth will be furthest from the Sun in July.
While the planet’s distance from the Sun is not responsible for the seasons, it does influence their length. As a function of gravity, the closer the planet is to the Sun, the faster it moves. Today, the Earth is 147.1 million kilometers (91.4 million miles) away from the Sun. That is approximately 5 million kilometers (3 million miles) closer than it will be in early July. This position allows the planet to speed up by about one-kilometer per second. As a result, winter in the northern hemisphere is about five days shorter than summer.
The word, perihelion, is Greek for “near sun”.
Earth is closest to the Sun during the northern hemisphere’s winter. Credit: TimeandDate.com
December 2017 felt like another temperature roller coaster in New York City. Highs ranged from an unseasonably warm 61°F to a frigid 18°F. But with eighteen out of thirty-one days posting below average readings, including the second coldest New Year’s Eve on record, the chill won out in the end. The city’s mean temperature for the month was 35°F, which is 2.5°F below average.
On the precipitation side of things, the city received 2.21 inches of rain. That is 1.79 inches below normal. December is now the sixth month in a row to deliver below average rainfall in NYC. As a result, the latest report from the US Drought Monitor (12/28) now lists the city as “abnormally dry.” Snowfall, on the other hand, was abundant. The month produced four separate snow events, including the city’s first snowfall of the season. In all, 7.7 inches of snow was measured in Central Park. On average, the city gets 4.8 inches of snow in December.
Credit: The Weather Gamut
The Holidays are here and many people are dreaming of a White Christmas. The likelihood of seeing those dreams come true, however, is 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, which has a moderating influence on the temperature. This year, with an area of low-pressure developing off the coast and cold arctic air moving in from the northwest, snow is a possibility for the Big Apple. It all depends on the track of the low. If it stays close to the coast, NYC will see rain or a wintry mix while inland areas will get snow. If the low moves further off-shore, the cold air will be able to push eastward and NYC will get snow for Christmas.
Snow or no snow, The Weather Gamut wishes you a very Happy Holiday!
The historical chances for a White Christmas across the continental US. Image Credit: NOAA
Today is the December solstice, the first day of winter in the northern hemisphere. The new season officially begins at 16:28 UTC, which is 11:28 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 southernmost 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.
Solstices and Equinoxes. Credit: NASA
The winter season can produce a number of different types of storms. One of these is an Alberta Clipper.
These systems originate in western Canada, on the lee side of the Rocky Mountains. As Pacific air spills downslope, an area of low pressure develops. From there, it gets caught up in the jet stream and moves to the southeast across the US. Traveling over land, these systems lack a significant source of moisture and generally do not produce much snow- usually around 1 to 3 inches. However, they are known for their strong winds and bitterly cold temperatures.
This type of quick-hitting storm takes its name not only from its place of origin near Alberta, Canada but also from the clipper ships of the 19th century – the fastest ships of the time.
Credit: NOAA
When winter rolls around, I am often reminded of the old Scandinavian saying: “There is no such thing as bad weather, only bad clothing choices.”
Since the weather is going to do whatever it is going to do, it is important to be prepared for anything that Mother Nature throws your 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