There is an old saying: “no two snowflakes are alike.” While that may well be true, their basic shapes are driven by temperature and atmospheric moisture content. Here is a look at their general categories.
Snowflake morphology diagram. Image Credit: Kenneth Libbrecht/CalTech
Another arctic outbreak has sent a large part of the US into a deep freeze. Across the East, temperatures tumbled this weekend with some places experiencing the coldest conditions they have seen in decades.
Here in New York City, the mercury fell to just 3°F in Central Park early Monday morning. That is the coldest temperature the city has seen in 11 years, but not quite a record. According to the NWS, the record low for the date was set in 1888 when the temperature was only 1°F. Our normal low for this time of year is 29°F.
Produced by a deep dip in the jet stream, our current frigid conditions will be staying in place for a while. In fact, a reinforcing shot of bitterly cold arctic air is expected to arrive in the region later this week. These types of temperatures can be life threatening, so remember to bundle up!
Frozen Fountain in NYC’s Bryant Park. Credit: FOX
Icicles are a classic symbol of cold winter weather. In order to form, however, they need a mix of both warm and cold conditions.
These hanging pieces of tapered ice develop when the air temperature is below freezing, but there is enough heat from the sun – or in the case of a building, a poorly insulated roof – to thaw some snow. As the melt water runs off the edge of a surface, it re-freezes in the cold air. Starting with only a few water droplets, an icicle can begin to form. Over time, as melt water continues to drip and re-freeze, an icicle gains both layers of thickness and length.
Often seen forming along the edge of roofs, icicles can also be found on tree branches, power lines, and rocks where water seeps out of the ground. The size and shape of an icicle, according to experts at the National Snow and Ice Data Center, depends on a few different factors. These include the shape of the surface on which it forms and the number of different directions from which melt water approaches the growing icicle.
Icicles can range in size from a few inches to tens of feet.
Icicles in the sunshine. Credit: MLE
We are only half way through winter and it seems some people have already had enough. I spotted this message-bearing, battered snow-person in Columbus Circle today as the Big Apple gears up for yet another round of wintry precipitation.
A winter weary snowman in Columbus Circle, NYC. Photo Credit: The Weather Gamut
Today is Groundhog Day, the midpoint of the winter season.
On this day, according to legend, the weather conditions for the second half of winter can be predicted by the behavior of a prognosticating groundhog. If the groundhog sees its shadow after emerging from its burrow, there will be six more weeks of winter. If it does not see its shadow, then spring will arrive early.
The practice of using animal behavior to predict future weather conditions goes back to ancient times. The particular custom that we are familiar with in the United States grew out of the old world tradition of Candlemas brought by German settlers to Pennsylvania in the 1880s. Today, many communities across the U.S. and Canada continue this age-old ritual with their own special groundhogs.
The most famous of these furry forecasters is Punxsutawney Phil from Pennsylvania – he was portrayed in the 1993 film, “Groundhog Day”. This year, despite an overcast sky, Phil saw his shadow and is calling for six more weeks of wintry conditions.
In New York City, our local weather-groundhog is Charles G. Hogg – more popularly known as “Staten Island Chuck”. Coming out of his burrow this morning, he did not see his shadow and is predicting an early spring for the Big Apple.
Long-range forecasts are a tricky business, so a difference of opinion is not that uncommon. Either way, the spring equinox is 46 days away.
January is typically the coldest month on the calendar for New York City and this year was no exception. We had nine days where the high temperature did not get above freezing and two overnight lows in the single digits. While there were also a few unseasonably warm days, the multiple bouts of extreme cold brought the city’s average monthly temperature down to 29.9°F. That is 2.7°F below normal.
On the precipitation side of things, the city had 11 days with measurable rainfall. In all, we received a remarkable 5.23 inches of rain, which is 1.58 inches above normal. Of this impressive total, 2.1 inches fell in a single day, January 18th, setting a new daily rainfall record for the date. Snow was also plentiful with 16.9 inches measured in Central Park. Most of this fell during a single storm – a clipper system that transitioned to a nor’easter – at the end of the month. On average, January usually brings the city a total of 7 inches of snow.
Credit: The Weather Gamut
Credit: The Weather Gamut
A major winter storm blasted a large area of the eastern U.S. on Monday and Tuesday. Heavy snow and high winds impacted states from the Mid-Atlantic to New England.
Here in New York City, the storm dumped 9.8 inches of snow in Central Park. While that is a substantial amount, it is a far cry from the record-breaking numbers and blizzard conditions that were forecast. In response to this forecast bust, the NWS said, “The science of forecasting storms, while continually improving, still can be subject to error, especially if we’re on the edge of the heavy precipitation shield. Efforts, including research, are already underway to more easily communicate that forecast uncertainty.”
Starting out as a weak area of low pressure, this storm quickly intensified when it interacted with the jet stream and transformed into a massive nor’easter. It tracked further east than expected and that change in distance to the coast made a big difference in where the heaviest snow fell. On Long Island, only a few miles east of NYC, communities dealt with blizzard conditions and over 20 inches of snow.
While not one for the record books in the Big Apple, this storm ended the so-called snow drought in the northeast and brought enough snow for a fun day of sledding in parks across the city.
A blizzard warning is currently in effect for New York City. The storm is expected to be our biggest snowmaker of the season to date. It could also possibly be one for the record books.
Here is a look at the top ten snowstorms in New York City history.
All measurements are from Central Park in NYC. Source: NWS.
A blizzard is expected to blast the northeastern United States over the next two days. Different than a typical winter storm, a blizzard is characterized more by its winds than the amount of snow it produces.
According to the National Weather Service, a blizzard means the following conditions prevail for three hours or longer:
These conditions heighten the risk for power outages and often produce whiteout conditions on roadways, making travel extremely dangerous.
The “Dead of Winter” is an old saying that refers to the coldest part of the winter season. This annual chilly period, statistically, begins today.
While actual daily weather varies, historical average temperatures in most of North America reach their lowest point of the year between January 10th and February 10th. This cold period does not begin on the winter solstice, the day we receive the least amount of solar energy, because of a phenomenon known as seasonal temperature lag.
Air temperature depends on both the amount of heat received from the sun and the amount of heat lost or absorbed by the oceans and continents. From the start of winter through mid-February, both the oceans and land are losing more heat than they gain.
These few cold weeks are the climatological opposite of the “Dog Days of Summer.”