How Hail Forms

The thunderstorms of spring and summer are notorious for their powerful winds and heavy rain. However, when strong enough, they can also produce hail.

Hailstones start off as water vapor that is lifted high into the atmosphere by the updraft of a thunderstorm. Rising into cooler air, it condenses and forms water droplets. Once these liquid droplets reach a level where the temperature is below freezing, they turn into tiny ice crystals. Overtime, they get larger as other water droplets freeze to them on contact, forming layers like an onion.  Once a hailstone gets too heavy for the updraft, it falls to the ground.

The stronger the updraft of a storm, the longer a hailstone remains suspended, and the larger it can grow. For a ball of ice to be considered a hailstone, according to the AMS, it has to measure at least 5mm in diameter.

The largest hailstone ever recorded in the US was found in Vivian, South Dakota on June 23, 2010. It measured 7.9 inches in diameter and weighed 1.94 pounds. The updraft supporting it would have had to exceed 150 mph.

Needless to say, hail can cause serious damage to people and property.

May 2018: Fifth Warmest on Record in NYC

May felt like a weather roller-coaster in New York City this year. Highs ranged from a cool 54°F to a record warm 92°F. However, with 20 out of 31 days posting above average readings, the warmth won out in the end. The city’s mean temperature for the month was 66.9°F, which is 4.5°F above average. That makes May 2018 the fifth warmest May on record in NYC.

On the precipitation side of things, May was below normal despite producing 13 days with measurable rainfall.  In all, 3.53 inches of rain was measured in Central Park. Of that total, 0.58 inches fell during a severe thunderstorm that swept through the city on May 15. The month, on average, brings the New York City 4.19 inches of rain.

Credit: The Weather Gamut

 

Suddenly Summer: Record Breaking Spring Heat in NYC

After a long cold winter and a chilly start to spring, it suddenly felt like summer in New York City this week.

According to the NWS, the temperature in Central Park hit 90°F on Wednesday. That marked the city’s first 90°F reading of the year and tied the daily record set in 2001. The sultry conditions continued on Thursday as the temperature climbed to 92°F, setting a new record high for the date. The previous record of 90°F had been in place since 2001.

Thursday’s low of 70°F was another record breaker, surpassing the old record of 68°F from 2001. In fact, this low reading was warmer than the date’s normal high. The city’s average high and low temperatures for this time of year are 67°F and 50°F, respectively.

These dramatic temperatures are the result of a Bermuda High, a large area of high pressure situated off the mid-Atlantic coast. Spinning clockwise, it has created a warm southwesterly flow of air into the northeast.

This summer-like weather brought many New Yorkers out of hibernation and into the city’s numerous parks and outdoor cafes. However, for some, the heat comes with a cost. It can lead to the formation of ground-level ozone, which is why an air quality advisory was issued for the area. Anyone with respiratory concerns, like asthma, has been advised to stay indoors.

While these temperatures are unseasonable, the city has seen 90° readings arrive even earlier. The earliest, according to NWS records, was April 7, 2010, when the mercury climbed to 92°F.

If you are not quite ready for summer, fear not. Conditions more typical of May are expected to return this weekend.

A week of weather whiplash for NYC. Credit: The Weather Gamut

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

Fourth Nor’easter of the Month Slams NYC

The calendar says spring, but it felt more like winter in New York City on Wednesday as the fourth nor’easter of the month slammed the region.

According to the NWS, the storm dumped 8.4 inches of heavy, wet snow in Central Park, setting a new daily snowfall record for the date. The previous record of 7.1 inches had been in place since 1958. The city, on average, gets 3.9 inches of snow for the entire month of March.

This storm was the fourth nor’easter to affect the city and region in less than three weeks. The others were on March 2, March 7, and March 13. This one, however, was by far the snowiest. It was also the first time since 1992 that the city saw at least 6 inches of snow from a spring storm.

The reason for the plethora of nor’easters this month involves something called the North Atlantic Oscillation (NAO). Stuck in its negative phase for weeks, it has caused the jet stream to dip south over the eastern US and steer storms toward the northeastern seaboard.

View of the fourth nor’easter to hit the east coast this March. Credit:  RAMMB/CIRA/CSU

February 2018: Warmest on Record in NYC

February 2018 was New York City’s warmest February on record. Its mean temperature of 42°F was a staggering 6.7°F above the long-term norm. The previous record of 41.6°F was set just last year in February 2017.

Overall, we had nineteen out of twenty-eight days that were warmer than normal. Five of those produced readings in the 60s and one even hit 78°F, marking the warmest February day ever recorded in NYC. A record warm minimum temperature was also set on February 21 when the city only cooled down to 55°F. The average low for that date is 30°F.

While a few warm days in February are not that uncommon, this extended pattern of sustained warmth was very unusual. Driven largely by a persistent ridge in the jet stream, warm southern air was funneled northward almost continuously throughout the month.

February is usually the city’s snowiest month on the calendar, but Central Park only received 4.9 inches of snow this year. That is 4.3 inches below normal. Of that total, 4.4 inches fell during a single, quick-hitting storm when the air was briefly cold enough to support frozen precipitation.

Rainfall, on the other hand, was abundant with seventeen days posting measurable precipitation. In total, Central Park reported 5.83 inches of rain. That is 2.74 inches above average.

New York City weather records date back to 1869.

February 2018 was the warmest February on record in NYC. Credit: The Weather Gamut

Spring Preview Brings NYC Warmest February Day Ever Recorded

The calendar says February, but it felt more like May in New York City on Wednesday. The temperature in Central Park soared to 78°F, setting not only a new record high for the date but marked the warmest February day ever recorded in the Big Apple.

Records are usually broken by fractions of a degree, but these were shattered. According to the NWS, the previous daily record, which was set in 1930, was 68°F and the former record monthly high that had been in place since February 24, 1985, was of 75°F. The city’s normal high this time of year is 43°F.

The primary driver of these unusually balmy conditions is a strong Bermuda High off the east coast of the US. Spinning clockwise, it is funneling warm southern air into the region.

Venturing out without coats and enjoying lunch alfresco, many New Yorkers took full advantage of this early spring preview. Personally, however, it felt a little surreal. February is typically the snowiest month of the year in NYC – a time when sledding and ice-skating are more common than ice-cream trucks and frisbees.

That said, these spring-like conditions will be short-lived. Temperatures are expected to return to more seasonable levels tomorrow. Get ready for weather whiplash!

Temperatures soared to record levels in NYC on Feb 21. Credit: The Weather Gamut

January 2018: Earth’s Fifth Warmest on Record

Our global temperature continued its upward trend last month with January 2018 marking the fifth warmest January ever recorded on this planet. The last four Januarys now rank among the five warmest on record.

According to a report by NOAA’s National Centers for Environmental Information, Earth’s combined average temperature for the month – over both land and sea surfaces – was 54.88°F. That is 1.28°F above the 20th-century average. January was also the 397th consecutive month with a global temperature above its long-term norm. That means the last time any month posted a below average reading was December 1984.

While heat dominated most of the planet this January, some places were particularly warm, including the western half of the United States and most of Europe. For the contiguous US as a whole, January ranked among warmest third of the nation’s 124-year period of record.

Coming on the heels of 2017 – Earth’s third warmest year on record and warmest year without an El Niño – these soaring temperatures are largely attributed to the long-term trend of human-caused climate change. In fact, La Niña conditions – the cool counterpart of El Niño – were present in the Pacific during January.

Global temperature records date back to 1880.

January 2018 was the planet’s 5th warmest January on record. Credit: NOAA

2017: Third Warmest Year on Record for Planet and the Warmest Year Without an El Niño

It is official, 2017 was the third warmest year ever recorded on this planet. Only 2015 and 2016 were warmer.

According to a report by NOAA’s National Centers for Environmental Information, Earth’s combined average temperature for the year – over both land and sea surfaces – was 58.51°F. That is a staggering 1.51°F above the 20th-century average.

2017 also marked the 41st consecutive year with a global temperature above its long-term norm. That means the last time any year posted a below average reading was 1976.

While heat dominated the planet last year, some places were particularly warm. Here in the contiguous US, it was our third warmest year on record.

The exceptional warmth of 2017 is largely attributed to the long-term trend of human-caused climate change. While El Niño conditions helped influence record heat in the past, 2017 was the warmest year on record without an El Niño being present in the Pacific. In fact, ENSO neutral conditions prevailed for most of the year and La Niña – the cool counterpart of El Niño – developed in the autumn.

Looking at the bigger picture, nine of the ten warmest years on record have occurred since the beginning of the 21st century. Three of those years – 2014, 2015, and 2016 – were back-to-back record breakers. As greenhouse gases – the main drivers of global warming – continue to spew into the atmosphere, temperatures will continue to rise and records will likely continue to fall.

Global temperature records date back to 1880.

2017 was the third warmest year on record for our planet. Credit: NOAA

Credit: NOAA

2017: Third Warmest Year on Record in US

2017 was the third-warmest year ever recorded in the continental United States. Only 2012 and 2016 were warmer.

The average annual temperature of the lower 48 states, according to a report by NOAA’s National Centers of Environmental Information, was 54.6°F. That is 2.6°F above the 20th-century average. 2017 also marked the 21st consecutive year that the annual average temperature for the contiguous US was above its long-term norm. That means the last time the US had a normal to below normal annual temperature was 1996.

From coast to coast, for the third year in a row, every state posted an above-average annual temperature. Five states – Arizona, Georgia, New Mexico, North Carolina, and South Carolina – had their warmest year on record. This was despite the unusually cold conditions that dominated the eastern part of the country in December.

The year was also notable for its unusual number of weather and climate disasters that each totaled more than $1 billion in damages. In all, sixteen such events collectively caused $306 billion in direct costs – a new US record. Sadly, they also claimed the lives of at least 362 people across the country. These incidents included drought, wildfire, floods, severe storms, and three major landfalling hurricanes.

The exceptional warmth of 2017 was independent of El Niño. In fact, ENSO neutral conditions prevailed for most of the year and La Niña – the cool counterpart of El Niño – developed in the autumn.

Weather records for the contiguous United States date back to 1895.

Credit: NOAA

Credit: NOAA